Federal Register, Volume 90 Issue 134 (Wednesday, July 16, 2025)

[Federal Register Volume 90, Number 134 (Wednesday, July 16, 2025)]
[Proposed Rules]
[Pages 32118-32349]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-13258]

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Vol. 90

Wednesday,

No. 134

July 16, 2025

Part II

Department of Commerce

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National Oceanic and Atmospheric Administration

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50 CFR Part 218

Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Military Readiness Activities in the
Hawaii-California Training and Testing Study Area; Proposed Rule

Federal Register / Vol. 90 , No. 134 / Wednesday, July 16, 2025 /
Proposed Rules

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 250708-0120]
RIN 0648-BN44

Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Military Readiness Activities in
the Hawaii-California Training and Testing Study Area

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.

ACTION: Proposed rule; proposed letters of authorization; request for
comments.

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SUMMARY: NMFS has received a request from the U.S. Department of the
Navy (including the U.S. Navy and the U.S. Marine Corps) (Navy) and on
behalf of the U.S. Coast Guard (Coast Guard) and U.S. Army (Army)
(hereafter, Navy, Coast Guard, and Army are collectively referred to as
the Action Proponents) for Incidental Take Regulations (ITR) and
multiple associated Letters of Authorization (LOAs) pursuant to the
Marine Mammal Protection Act (MMPA). The requested regulations would
govern the authorization of take of marine mammals incidental to
training and testing activities, and modernization and sustainment of
ranges conducted in the Hawaii-California Training and Testing (HCTT)
Study Area over the course of seven years from December 2025 through
December 2032. NMFS requests comments on this proposed rule. NMFS will
consider public comments prior to making any final decision on the
promulgation of the requested ITR and issuance of the LOAs; agency
responses to public comments will be summarized in the final rule, if
issued. The Action Proponents' activities are considered military
readiness activities pursuant to the MMPA, as amended by the National
Defense Authorization Act for Fiscal Year 2004 (2004 NDAA) and the NDAA
for Fiscal Year 2019 (2019 NDAA).

DATES: Comments and information must be received no later than August
15, 2025.

ADDRESSES: A plain language summary of this proposed rule is available
at: https://www.regulations.gov/docket/NOAA-NMFS-2025-0028. You may
submit comments on this document, identified by NOAA-NMFS-2025-0028, by
any of the following methods:
Electronic Submission: Submit all electronic public
comments via the Federal e-Rulemaking Portal. Visit https://www.regulations.gov and type NOAA-NMFS-2025-0028 in the Search box.
Click on the ``Comment'' icon, complete the required fields, and enter
or attach your comments.
Mail: Submit written comments to Ben Laws, Incidental Take
Program Supervisor, Permits and Conservation Division, Office of
Protected Resources, National Marine Fisheries Service, 1315 East-West
Highway, Silver Spring, MD 20910-3225.
Fax: (301) 713-0376; Attn: Ben Laws.
Instructions: Comments sent by any other method, to any other
address or individual, or received after the end of the comment period,
may not be considered by NMFS. All comments received are a part of the
public record and will generally be posted for public viewing at:
https://www.regulations.gov without change. All personal identifying
information (e.g., name, address, etc.), confidential business
information, or otherwise sensitive information submitted voluntarily
by the sender will be publicly accessible. NMFS will accept anonymous
comments (enter ``N/A'' in the required fields if you wish to remain
anonymous). Attachments to electronic comments will be accepted in
Microsoft Word, Excel, or Adobe PDF file formats only.
A copy of the Action Proponents' Incidental Take Authorization
(ITA) application and supporting documents, as well as a list of the
references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems
accessing these documents, please call the contact listed below (see
FOR FURTHER INFORMATION CONTACT).

FOR FURTHER INFORMATION CONTACT: Leah Davis, Office of Protected
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Purpose and Need for Regulatory Action

This proposed rule, if promulgated, would provide a framework under
the authority of the MMPA (16 U.S.C. 1361 et seq.) to allow for the
authorization of take of marine mammals incidental to the Action
Proponents' training and testing activities and modernization and
sustainment of ranges (which qualify as military readiness activities)
involving the use of active sonar and other transducers, air guns, and
explosives (also referred to as ``in-water detonations''); pile driving
and vibratory extraction; land-based missile and target launches; and
vessel movement in the HCTT Study Area. The HCTT Study Area includes
areas in the north-central Pacific Ocean, from California west to
Hawaii and the International Date Line, and including the Hawaii Range
Complex (HRC) and Temporary Operating Area (TOA), Southern California
(SOCAL) Range Complex, Point Mugu Sea Range (PMSR), Silver Strand
Training Complex, areas along the Southern California coastline from
approximately Dana Point to Port Hueneme, and the Northern California
(NOCAL) Range Complex (see figure 1.1-1 of the rulemaking and LOA
application (hereafter referred to as the application)). Please see the
Legal Authority for the Proposed Action section for relevant
definitions.

Legal Authority for the Proposed Action

The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed authorization is provided to the public for review and the
opportunity to submit comment.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking; other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (collectively referred to as
``mitigation''); and requirements pertaining to the monitoring and
reporting of the takings. The MMPA defines ``take'' to mean to harass,
hunt, capture, or kill, or attempt to harass, hunt, capture, or kill
any marine mammal (16 U.S.C. 1362). The Preliminary Analysis and
Negligible

[[Page 32119]]

Impact Determination section discusses the definition of ``negligible
impact.''
The 2004 NDAA (Pub. L. 108-136) amended section 101(a)(5) of the
MMPA to remove the ``small numbers'' and ``specified geographical
region'' provisions, 16 U.S.C. 1371(a)(5)(F), and amended the
definition of ``harassment'' in section 3(18)(B) of the MMPA as applied
to a ``military readiness activity'' to read as follows: (1) Any act
that injures or has the significant potential to injure a marine mammal
or marine mammal stock in the wild (Level A Harassment); or (2) Any act
that disturbs or is likely to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of natural behavioral patterns,
including, but not limited to, migration, surfacing, nursing, breeding,
feeding, or sheltering, to a point where such behavioral patterns are
abandoned or significantly altered (Level B Harassment). 16 U.S.C.
1362(18)(B). The 2004 NDAA also amended the MMPA to establish in
section 101(a)(5)(A)(iii) that ``[f]or a military readiness activity .
. . , a determination of `least practicable adverse impact' . . . shall
include consideration of personnel safety, practicality of
implementation, and impact on the effectiveness of the military
readiness activity.'' 16 U.S.C. 1371(a)(5)(A)(iii). On August 13, 2018,
the 2019 NDAA (Pub. L. 115-232) amended the MMPA to allow ITRs for
military readiness activities to be issued for up to 7 years. 16 U.S.C.
1371(a)(5)(A)(ii).

Summary of Major Provisions Within the Proposed Rule

The major provisions of this proposed rule are as follows:
The proposed authorization of take of marine mammals by
Level A harassment and/or Level B harassment;
The proposed authorization of take of marine mammals by
mortality or serious injury (M/SI);
The proposed use of defined powerdown and shutdown zones
(based on activity);
Proposed measures to reduce the likelihood of vessel
strikes;
Proposed activity limitations in certain areas and times
that are biologically important (i.e., for foraging, migration,
reproduction) for marine mammals;
The proposed implementation of a Notification and
Reporting Plan (for dead, live stranded, or marine mammals struck by
any vessel engaged in military readiness activities); and
The proposed implementation of a robust monitoring plan to
improve our understanding of the environmental effects resulting from
the Action Proponents' training and testing activities and
modernization and sustainment of ranges.
This proposed rule includes an adaptive management component that
allows for timely modification of mitigation, monitoring, and/or
reporting measures based on new information, when appropriate.

Summary of Request

On September 16, 2024, NMFS received an application from the Action
Proponents requesting authorization to take marine mammals, by Level A
and Level B harassment, incidental to training, testing, and
modernization and sustainment of ranges (characterized as military
readiness activities) including the use of sonar and other transducers,
explosives, air guns, impact and vibratory pile driving and extraction,
and land-based missile and target launches conducted within the HCTT
Study Area. The Action Proponents also request authorization to take,
by serious injury or mortality, a limited number of marine mammal
species incidental to the use of explosives and vessel movement during
military readiness activities conducted within the HCTT Study Area. The
Action Proponents are requesting multiple 7-year LOAs for Navy training
activities, Coast Guard training activities, Army training activities,
and Navy testing activities. In response to our comments and following
an information exchange, the Action Proponents submitted a revised
application, deemed adequate and complete on December 13, 2024. On that
same date, we published a notice of receipt of application in the
Federal Register (89 FR 100982), requesting comments and information
related to the Action Proponents' request for 30 days. During the 30-
day public comment period on the NOR, we received one public comment
from the Center for Biological Diversity. NMFS reviewed and considered
all submitted material during the drafting of this proposed rule.
NMFS has previously promulgated ITRs pursuant to the MMPA relating
to similar military readiness activities in areas located within the
HCTT Study Area. NMFS published the first rule effective from January
5, 2009 through January 5, 2014, (74 FR 1456, January 12, 2009), the
second rule effective from December 24, 2013 through December 24, 2018
(78 FR 78106, December 24, 2013), and the third rule effective from
December 21, 2018 through December 20, 2023 (83 FR 66846, December 27,
2018), which was subsequently amended, extending the effective date
until December 20, 2025 (85 FR 41780, July 10, 2020) pursuant to the
2019 NDAA and later further amended to increase the take of large
whales by vessel strike and modify the mitigation, monitoring, and
reporting measures to reduce vessel strikes (90 FR 4944, January 16,
2025). For this proposed rulemaking, the Action Proponents propose to
conduct substantially similar training and testing activities within
the HCTT Study Area that were conducted under previous rules (noting
that the Study Area has been expanded, as described in the Geographic
Region section).
The Action Proponents' application reflects the most up-to-date
compilation of training and testing activities, and modernization and
sustainment of ranges deemed necessary to accomplish military readiness
requirements. The types and numbers of activities included in the
proposed rule account for interannual variability in training and
testing to meet evolving or emergent military readiness requirements.
As explained herein, these proposed regulations also consolidate
several actions conducted by the Navy that were previously authorized
by NMFS and include some new military readiness activities carried out
by the Action Proponents. In particular, these proposed regulations
would cover incidental take during military readiness activities in the
HCTT Study Area that would occur for a 7-year period following the
expiration of the existing MMPA authorization which expires on December
20, 2025 (85 FR 41780, as amended by 90 FR 4944). In addition, this
proposed rule includes PMSR activities for which incidental take has
previously been authorized under separate authorizations, and, if
finalized, this rule would supersede the most recent PMSR regulations
(87 FR 40888, July 8, 2022). This proposed rule also includes areas
along the Southern California coastline from approximately Dana Point
to Port Hueneme and would supersede the incidental harassment
authorization (IHA) allowing incidental take of marine mammals during
pile driving training activities at Port Hueneme (90 FR 20283, May 13,
2025). In this proposed rule, we have undertaken a comprehensive
assessment of the risks/impacts of all military training and testing
activities on marine mammals likely to be present within the entire
range of the Study Area.

Description of Proposed Activity

Overview

The Action Proponents request authorization to take marine mammals

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incidental to conducting military readiness activities. The Action
Proponents have determined that acoustic and explosives stressors are
likely to result in take of marine mammals in the form of Level A and B
harassment, and that a limited number of takes by serious injury or
mortality may result from vessel movement and use of explosives
(including ship shock trials). Detailed descriptions of these
activities are provided in chapter 2 and appendix A of the 2024 HCTT
Draft Environmental Impact Statement/Overseas Environmental Impact
Statement (2024 HCTT Draft EIS/OEIS) (https://www.nepa.navy.mil/hctteis/) and in the Action Proponents' application (https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities), which are
summarized here. Of note, the U.S. Air Force (USAF) is a joint lead
agency for the 2024 HCTT Draft EIS/OEIS; USAF activities consist of air
combat maneuvers and air-to-air gunnery (a gunnery exercise in which
fixed-wing aircraft fire medium caliber guns at air targets). The
Action Proponents determined that USAF activities would not result in
the take of marine mammals, and therefore these activities are not
included in the Action Proponents' application. NMFS concurs that these
activities are not anticipated to result in incidental take of marine
mammals.
The Navy's statutory mission is to organize, train, equip, and
maintain combat-ready naval forces for the peacetime promotion of the
national security interests and prosperity of the United States, and
for prompt and sustained combat incident to operations essential to the
prosecution of a naval campaign. This mission is mandated by Federal
law (10 U.S.C. 8062 and 10 U.S.C. 8063), which requires the readiness
of the naval forces of the United States. The Navy executes this
responsibility by establishing and executing at-sea training and
testing, often in designated operating areas (OPAREAs) and testing and
training ranges. The Navy must be able to access and utilize these
areas and associated sea and air space to develop and maintain skills
for conducting naval operations. The Navy's testing activities ensure
naval forces are equipped with well-maintained systems that take
advantage of the latest technological advances. The Navy's research and
acquisition community conducts military readiness activities that
involve testing. The Navy tests vessels, aircraft, weapons, combat
systems, sensors, and related equipment, and conducts scientific
research activities to achieve and maintain military readiness.
The mission of the Coast Guard is to ensure the maritime safety,
security, and stewardship of the United States. To advance this
mission, the Coast Guard must ensure its personnel can qualify and
train jointly with, and independently of, the Navy and other services
in the effective and safe operational use of Coast Guard vessels,
aircraft, and weapons under realistic conditions. These activities help
ensure the Coast Guard can safely assist in the defense of the United
States by protecting the United States' maritime safety, security, and
natural resources in accordance with its national defense mission (14
U.S.C. 102). Coast Guard training, which accounts for a small portion
of overall activities, is summarized below.
The Army is increasingly required to support the naval mission,
frequently training in concert with the Navy. Some of this training
includes the use of explosives in the marine environment.

Dates and Duration

The specified activities would occur at any time during the 7-year
period of validity of the regulations. The proposed number of military
readiness activities are described in the Detailed Description of the
Specified Activity section (table 2 through table 9).

Geographic Region

The HCTT Study Area includes areas in the north-central Pacific
Ocean, from California west to Hawaii and the International Date Line,
and including the HRC and TOA, SOCAL Range Complex, PMSR, Silver Strand
Training Complex, and the NOCAL Range Complex. The HRC encompasses
ocean areas around the Hawaiian Islands, extending from 16 degrees
north latitude to 43 degrees north latitude and from 150 degrees west
longitude to the International Date Line (figure 1). It also includes
pierside locations and port transit channels, bays, harbors, inshore
waterways, amphibious approach lanes, and civilian ports where military
readiness activities occur as well as transits between homeports and
the Hawaii and California Study Areas. The geographic extent of the HRC
remains the same and has not changed since the last rulemaking. The
SOCAL Range Complex is located between Dana Point, California and San
Antonio, Mexico, and extends southwest into the Pacific Ocean. The PMSR
is located adjacent to Los Angeles, Ventura, Santa Barbara, and San
Luis Obispo Counties along the Pacific Coast of Southern California.
The Silver Strand Training Complex is an integrated set of training
areas located on and adjacent to the Silver Strand, a narrow, sandy
isthmus separating the San Diego Bay from the Pacific Ocean. The NOCAL
Range Complex consists of two separate areas located offshore of
central and northern California, one northwest of San Francisco and the
other southwest of Monterey Bay.
The SOCAL Range Complex expansion, which is new, and incorporation
of existing NOCAL Range Complex and the PMSR, are revisions for the
HCTT Study Area (formerly HSTT (Hawaii-Southern California Training and
Testing) Study Area) in this application (noting that take from
activities at PMSR are currently authorized under a separate rule (87
FR 40888, July 8, 2022)).
This proposed rule also incorporates areas along the Southern
California coastline from approximately Dana Point to Port Hueneme and
includes the new IHA allowing incidental take of marine mammals during
pile driving training activities at Port Hueneme (90 FR 20283, May 13,
2025).
Please refer to figure 1.1-1 of the application for a color map of
the HCTT Study Area and figure 2-1 through figure 2-17 for additional
maps of the range complexes, training and testing ranges, and other
notable areas. A summary of the HCTT Study Area Training and Testing
Ranges are provided in table 1.
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Table 1--HCTT Study Area Training and Testing Ranges
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Spatial extent
Name Basic location (air, sea, and
undersea space)
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Hawaii Range Complex (HRC).... Ocean areas around 235,000 nmi\2\
main Hawaiian islands (80,602,744
from 16 degrees north ha).
latitude to 43
degrees north
latitude and from 150
degrees west
longitude to the
International Date
Line.
Temporary Operating Area (TOA) North and west from 2,000,000 nmi\2\
the island of (585,980,800
Kaua[revaps]i. ha).
Southern California Range Off San Diego County 217,000 nmi\2\
Complex (SOCAL). out to approximately (74,428,916
550 nmi (1,109 km). ha).
Silver Strand Training Complex Subset of areas within 16 nmi\2\ (5,488
San Diego Bay and ha).
adjacent to ocean out
to approximately 4
nmi.
Point Mugu Sea Range (PMSR)... Off Los Angeles and 36,000 nmi\2\
Ventura Counties out (12,347,654
to approximately 400 ha).
nmi.
Northern California Range Two separate areas 16,000 nmi\2\
Complex (NOCAL). located offshore of (5,487,846 ha).
central and northern
California, one
northwest of San
Francisco and the
other southwest of
Monterey Bay.
------------------------------------------------------------------------
Note: nmi\2\ = square nautical miles, ha = hectares, nmi = nautical
miles, km = kilometer. Ports included in HCTT: San Diego Bay,
California; Port Hueneme, California; and Pearl Harbor, Hawaii.

Detailed Description of the Specified Activity

The Action Proponents propose to conduct military readiness
activities within the HCTT Study Area and have been conducting military
readiness activities in the Study Area since the 1940s. The tempo and
types of military readiness activities have varied interannually due to
the introduction of new technologies, the evolving nature of
international events, advances in warfighting doctrine and procedures,
and changes in force structure (organization of vessels, weapons, and
personnel). Such developments influence the frequency, duration,
intensity, and location of required military readiness activities.
Primary Mission Areas
The Navy categorizes their activities into functional warfare areas
called primary mission areas, while the Coast Guard categorizes their
activities as operational mission programs. For the Navy, these
activities generally fall six primary mission areas (Coast Guard
mission areas are discussed below). The Navy mission areas with
activities that may result in take of marine mammals (and stressors
associated with training and testing activities within those mission
areas) include the following:
Amphibious warfare (in-water detonations);
Anti-submarine warfare (sonar and other transducers, in-
water detonations);
Expeditionary warfare (in-water detonations, pile driving
and extraction);
Mine warfare (sonar and other transducers, in-water
detonations);
Surface warfare (in-water detonations and those occurring
at or near the surface); and
Other (sonar and other transducers, air guns, vessel
movement, airborne noise from missile and target launches from San
Nicolas Island (SNI) and from shore-to-surface gunnery and missile and
aerial target launches from the Pacific Missile Range Facility (PMRF),
unmanned systems training, and maintenance of ship and submarine sonar
at piers and at-sea).
Most Navy activities conducted in HCTT are categorized under one of
these primary mission areas; activities that do not fall within one of
these areas are listed as ``other activities.'' In addition, ship shock
(underwater detonations) trials, a specific Navy testing activity
related to vessel evaluation, would be conducted. The testing community
also categorizes most, but not all, of its testing activities under
these primary mission areas. The testing community has three additional
categories of activities: vessel evaluation (including ship shock
trials), unmanned systems (i.e., unmanned surface vehicles (USVs),
unmanned underwater vehicles (UUVs)), and acoustic and oceanographic
science and technology.
The Action Proponents describe and analyze the effects of their
activities within the application (see the 2024 HCTT Draft EIS/OEIS for
additional details). In their assessment, the Action Proponents
concluded that sonar and other transducers, explosives (in-water
detonations and those occurring at or near the surface), air guns,
land-based missile and target launches, and pile driving/extraction
were the stressors most likely to result in impacts on marine mammals
that qualify as harassment (and serious injury or mortality by
explosives or vessel strike) as defined under the MMPA. Therefore, the
Action Proponents' application provides their assessment of potential
effects from these stressors in terms of the primary warfare mission
areas in which they would be conducted.
The Coast Guard has four major national defense missions:
Maritime intercept operations;
Deployed port operations/security and defense;
Peacetime engagement; and
Environmental defense operations (including oil and
hazardous substance response).
The Coast Guard manages 6 major operational mission programs with
11 statutory missions, which includes defense readiness. As part of the
Coast Guard's defense mission, 14 U.S.C. 1 states the Coast Guard is
``at all times an armed force of the United States.'' As part of the
Joint Forces, the Coast Guard maintains its readiness to carry out
military operations in support of the policies and objectives of the
U.S. government. As an armed force, the Coast Guard trains and operates
in the joint military arena at any time and functions as a specialized
service under the Navy in time of war or when directed by the
President. Coast Guard service members are trained to respond
immediately to support military operations and national security.
Federal law created the framework for the relationship between the Navy
and the Coast Guard (10 U.S.C. 101; 14 U.S.C. 2 (7); 22 U.S.C. 2761; 50
U.S.C. 3004). To meet these statutory requirements and effectively
carry out these missions, the Coast Guard's air and surface units train
using realistic scenarios, including training with the Navy in their
primary mission areas. Every Coast Guard unit is trained to support all
statutory missions and, thus, trained to meet all mission requirements,
which includes their defense mission requirements. Since all Coast
Guard's missions generally entail the deployment of cutters or boats
and either fixed-wing or rotary aircraft, the Coast Guard training
requirements for one mission generally overlaps with the training
requirements of other missions. Thus, when the Coast Guard is training

[[Page 32123]]

for its defense mission, the same skill sets are utilized for its other
statutory missions.
The Coast Guard's defense mission does not involve use of low- or
mid-frequency active sonar (LFAS or MFAS), missiles, in-water
detonations, pile driving and vibratory extraction, or air guns that
would result in harassment of marine mammals.
The Army's mission is mandated by Federal law (10 U.S.C. 7062),
which requires an Army capable of, in conjunction with the other armed
forces:
Preserving the peace and security, and providing for the
defense, of the United States, the Commonwealths and possessions, and
any areas occupied by the United States;
Supporting the national policies;
Implementing the national objectives; and
Overcoming any nations responsible for aggressive acts
that imperil the peace and security of the United States.
In general, the Army includes land combat and service forces, as
well as aviation and water transport. It shall be organized, trained,
and equipped primarily for prompt and sustained combat incident to
operations on land. It is responsible for the preparation of land
forces necessary for the effective prosecution of war except as
otherwise assigned and, in accordance with integrated joint
mobilization plans, for the expansion of the peacetime components of
the Army to meet the needs of war.
The Army is increasingly required to operate in the marine
environment and with the Navy and, therefore, have an increased
requirement to train in the maritime environment. The Army's activities
include only the use of explosives, and do not include the use of
sonars or other transducers, pile driving and vibratory extraction, or
air guns that would result in harassment of marine mammals.
Below, we provide additional detail for each of the applicable
primary mission areas.
Amphibious Warfare--
The mission of amphibious warfare is to project military power from
the sea to the shore (i.e., attack a threat on land by a military force
embarked on ships) through the use of naval firepower and expeditionary
landing forces. Amphibious warfare operations include Army, Navy, and
Marine Corps small unit reconnaissance or raid missions to large-scale
amphibious exercises involving multiple ships and aircraft combined
into a strike group.
Amphibious warfare training ranges from individual, crew, and small
unit events to large task force exercises. Individual and crew training
includes amphibious vehicles and naval gunfire support training. Such
training includes shore assaults, boat raids, airfield or port
seizures, reconnaissance, and disaster relief. Large-scale amphibious
exercises involve ship-to-shore maneuvers, naval fire support such as
shore bombardment, air strikes, shore-based missile and artillery
firing, and attacks on targets that are near friendly forces. Some
amphibious activities include firing at ships from shore in defense of
the amphibious objective.
Testing of guns, munitions, aircraft, ships, and amphibious vessels
and vehicles used in amphibious warfare are often integrated into
training activities and, in most cases, the systems are used in the
same manner in which they are used for training activities. Amphibious
warfare tests, when integrated with training activities or conducted
separately as full operational evaluations on existing amphibious
vessels and vehicles following maintenance, repair, or modernization,
may be conducted independently or in conjunction with other amphibious
ship and aircraft activities. Testing is performed to ensure effective
ship-to-shore coordination and transport of personnel, equipment, and
supplies. Tests may also be conducted periodically on other systems,
vessels, and aircraft intended for amphibious operations to assess
operability and to investigate efficacy of new technologies.
Anti-Submarine Warfare--
The mission of anti-submarine warfare is to locate, neutralize, and
defeat hostile submarine forces that threaten Navy forces. Anti-
submarine warfare is based on the principle that surveillance and
attack aircraft, ships, and submarines all search for hostile
submarines. These forces operate together or independently to gain
early warning and detection and to localize, track, target, and attack
submarine threats.
Anti-submarine warfare training addresses basic skills such as
detecting and classifying submarines, as well as evaluating sounds to
distinguish between enemy submarines and friendly submarines, ships,
and marine life. More advanced training integrates the full spectrum of
anti-submarine warfare from detecting and tracking a submarine to
attacking a target using either exercise torpedoes (i.e., torpedoes
that do not contain a warhead) or simulated weapons. These integrated
anti-submarine warfare training exercises are conducted in coordinated,
at-sea training events involving submarines, ships, and aircraft.
Testing of anti-submarine warfare systems is conducted to develop
new technologies and assess weapon performance and operability with new
systems and platforms, such as unmanned systems. Testing uses ships,
submarines, and aircraft to demonstrate capabilities of torpedoes,
missiles, countermeasure systems, and underwater surveillance and
communications systems. Tests may be conducted as part of a large-scale
fleet training event involving submarines, ships, fixed-wing aircraft,
and helicopters. These integrated training events offer opportunities
to conduct research and acquisition activities and to train aircrew in
the use of new or newly enhanced systems during a large-scale, complex
exercise.
Expeditionary Warfare--
The mission of expeditionary warfare is to provide security and
surveillance in the littoral (i.e., at the shoreline), riparian (i.e.,
along a river), or coastal environments. Expeditionary warfare is wide
ranging and includes defense of harbors, operation of remotely operated
vehicles, clearing obstacles, small boat attack, and boarding/seizure
operations.
Expeditionary warfare training activities conducted by the Action
Proponents include underwater construction team training, diver
propulsion device training and testing, parachute insertion, dive and
salvage operations, and insertion/extraction via air, surface, and
subsurface platforms, among others (see appendix A (Activity
Descriptions) of the 2024 HCTT Draft EIS/OEIS for a full description of
the expeditionary warfare activities).
Mine Warfare--
The mission of mine warfare is to detect, classify, and avoid or
neutralize (i.e., disable) mines to protect U.S. ships and submarines,
and to maintain free access to ports and shipping lanes. Mine warfare
training for the Navy falls into two primary categories: mine detection
and classification, and mine countermeasure and neutralization. Mine
warfare also includes offensive mine laying to gain control of or deny
the enemy access to sea space. Naval mines can be laid by ships,
submarines, UUVs, or aircraft.
Mine warfare neutralization training includes exercises in which
aircraft, ships, submarines, underwater vehicles, unmanned vehicles, or
marine mammal detection systems search for mine shapes. Personnel train
to destroy or disable mines by attaching underwater

[[Page 32124]]

explosives to or near the mine or using remotely operated vehicles to
destroy the mine. Towed influence mine sweep systems mimic a particular
ship's magnetic and acoustic signature, which would trigger a real mine
causing it to explode.
Testing and development of mine warfare systems is conducted to
improve sonar, laser, and magnetic detectors intended to hunt, locate,
and record the positions of mines for avoidance or subsequent
neutralization. Mine detection and classification testing involves the
use of air, surface, and subsurface vessels and uses sonar, including
towed and side-scan sonar, and unmanned vehicles to locate and identify
objects underwater. Mine detection and classification systems are
sometimes used in conjunction with a mine neutralization system. Mine
countermeasure and neutralization testing includes the use of air,
surface, and subsurface units and uses tracking devices, countermeasure
and neutralization systems, and general purpose bombs to evaluate the
effectiveness of neutralizing mine threats. Most neutralization tests
use mine shapes, or non-explosive practice mines, to accomplish the
requirements of the activity. For example, during a mine neutralization
test, a previously located mine is destroyed or rendered nonfunctional
using a helicopter or manned surface vehicle/USV-based system that may
involve the deployment of a towed neutralization system.
A small percentage of mine warfare testing activities require the
use of high-explosive mines to evaluate and confirm the ability of the
system to neutralize a high-explosive mine under operational
conditions. Only a subset of all mine warfare training areas are
approved for underwater explosive use (see figures 2-5, 2-11, and 2-12
of the application). The majority of mine warfare systems are deployed
by ships, helicopters, and unmanned vehicles. Tests may also be
conducted in support of scientific research to support these new
technologies (see appendix H (Description of Systems and Ranges) of the
2024 HCTT Draft EIS/OEIS for additional details).
Surface Warfare--
The mission of surface warfare is to obtain control of sea space
from which naval forces may operate and entails offensive action
against surface and subsurface targets while also defending against
enemy forces. In surface warfare, aircraft use guns, air-launched
cruise missiles, or other precision-guided munitions; ships employ
naval guns and surface-to-surface missiles; and submarines attack
surface ships using torpedoes or submarine-launched, anti-ship cruise
missiles.
Surface warfare training includes Navy, Coast Guard, and Army
surface-to-surface gunnery and missile exercises, air-to-surface
gunnery, bombing, and missile exercises, submarine missile or torpedo
launch events, other munitions against surface targets, and amphibious
operations in a contested environment.
Testing of weapons used in surface warfare is conducted to develop
new technologies and to assess weapon performance and operability with
new systems and platforms, such as unmanned systems. Tests include
various air-to-surface guns and missiles, surface-to-surface guns and
missiles, and bombing tests. Testing events may be integrated into
training activities to test aircraft or aircraft systems in the
delivery of ordnance on a surface target. In most cases the tested
systems are used in the same manner in which they are used for training
activities.
Other Training Activities--
Other training activities are conducted in the HCTT Study Area that
fall outside of the primary mission areas but support overall
readiness. These activities include sonar and other transducers, vessel
movement, missile and target launch noise from locations on SNI and
PMRF, artillery firing noise from shore to surface gunnery at PMRF,
unmanned systems training, and maintenance of ship and submarine sonar
at piers and at-sea.
Overview of Training Activities Within the Study Area
The Action Proponents routinely train in the HCTT Study Area in
preparation for national defense missions. Training activities and
exercises covered in this proposed rule are briefly described below and
in more detail within appendix A (Activity Descriptions) of the 2024
HCTT Draft EIS/OEIS. The description, annual number of activities, and
location of each training activity are provided by stressor category in
table 2 through table 5. Each training activity described meets a
requirement that can be traced ultimately to requirements set forth by
the National Command Authority.
Within the Navy, a major training exercise (MTE) is comprised of
multiple ``unit-level'' range exercises conducted by several units
operating together while commanded and controlled by a single
commander. These units are collectively referred to as carrier and
expeditionary strike groups. These exercises typically employ an
exercise scenario developed to train and evaluate the strike group in
tactical naval tasks. In a MTE, most of the operations and activities
being directed and coordinated by the strike group commander are
identical in nature to the operations conducted during individual,
crew, and smaller unit-level training events. However, in MTEs, these
disparate training tasks are conducted in concert rather than in
isolation. Some integrated or coordinated anti-submarine warfare
exercises are similar in that they are composed of several unit-level
exercises but are generally on a smaller scale than a MTE, are shorter
in duration, use fewer assets, and use fewer hours of hull-mounted
sonar per exercise. Coordinated training exercises involve multiple
units working together to meet unit-level training requirements,
whereas integrated training exercises involve multiple units working
together in preparation for deployment. Coordinated exercises involving
the use of sonar are presented under the category of anti-submarine
warfare. The anti-submarine warfare portions of these exercises are
considered together in coordinated activities for the sake of acoustic
modeling. When other training objectives are being met, those
activities are described via unit-level training in each of the
relevant primary mission areas.
With a smaller fleet of approximately 250 cutters, Coast Guard
activities are not as extensive as Navy activities due to differing
mission requirements. However, the Coast Guard does train with the Navy
and conducts some of the same training as the Navy. The Coast Guard
does not conduct any exercises similar in scale to Navy MTEs/integrated
exercises, and the use of mid- or low-frequency sonar, missiles, and
underwater detonations are examples of actions that are not a part of
the Coast Guard's mission requirements. Coast Guard training generally
occurs close to the vessel homeport or close to shore, on established
Navy training and testing ranges, or in transit to a scheduled patrol/
mission. There are approximately 1,600 Coast Guard vessels (cutters up
to 418 feet (ft); 127.4 meters (m) and boats less than 65 ft (19.8 m)),
and the largest cutters would be underway for 3-4 months, whereas the
smaller cutters would be underway from a few days to 4 weeks. Within
California, there are approximately 20 cutters homeported. Cutters are
defined as vessels larger than 65 ft (19.8 m). The service has about
1,680 boats nation-wide altogether. These craft include heavy weather
response boats, special purpose craft,

[[Page 32125]]

aids-to-navigation (ATON) boats, and cutter-based boats. Sizes range
from 64 ft (29.5 m) in length down to 12 ft (3.7 m). There are
approximately 100 boats in California but the number of boats varies.
Within Hawaii, the Coast Guard has eight cutters and an unspecified
number of small boats homeported.
The MTEs and integrated/coordinated training activities analyzed
for this request are Navy-led exercises in which the Coast Guard may
participate and described in table 2. For additional information on
these activities see table 1-8 of the application and appendix A
(Activity Descriptions) of the 2024 HCTT Draft EIS/OEIS. Table 3
describes the proposed Navy training activities analyzed within the
HCTT Study Area while table 4 describes the proposed Coast Guard
training activities analyzed within the HCTT Study Area and table 5
describes the Army training activities analyzed within the HCTT Study
Area. In addition to participating in Navy-led exercises, Coast Guard
and Army training activities include unit-level activities conducted
independently of, and not in coordination with, the Navy.

Table 2--MTEs and Integrated/Coordinated Training Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Typical
hull-mounted
Training type Exercise group Description Scale Duration Location (range Exercise sonar per
complex) examples event
(hours)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Major Training Exercise....... Large Integrated Larger-scale, Greater than 6 Generally SOCAL, PMSR, HRC Strike Group >500
ASW. longer duration surface ASW greater than 10 COMPUTEX,
integrated ASW units (up to 30 days. RIMPAC.
exercises. with the
largest
exercises), 2
or more
submarines,
multiple ASW
aircraft.
Major Training Exercise....... Medium Medium-scale, Approximately 3- Generally 4-10 SOCAL, PMSR, HRC Task Force/ 100-500
Integrated ASW. medium duration 8 surface ASW days. Sustainment
integrated ASW units, at least Exercise, Multi-
exercises. 1 submarine, Warfare
multiple ASW Exercise.
aircraft.
Integrated/Coordinated Small Integrated Small-scale, Approximately 3- Generally less SOCAL, HRC...... SWATT, NUWTAC... 50-100
Training. ASW. short duration 6 surface ASW than 5 days.
integrated ASW units, 2
exercises. dedicated
submarines, 2-6
ASW aircraft.
Integrated/Coordinated Medium Medium-scale, Approximately 2- Generally 3-10 SOCAL, HRC...... SCC, Fleet <100
Training. Coordinated ASW. medium 4 surface ASW days. Battle Problem,
duration, units, possibly TACDEVEX.
coordinated ASW a submarine, 2-
exercises. 5 ASW aircraft.
Integrated/Coordinated Small Small-scale, Approximately 2- Generally 2-4 SOCAL, HRC...... ID CERTEX....... <50
Training. Coordinated ASW. short duration, 4 surface ASW days.
coordinated ASW units, possibly
exercises. a submarine, 1-
2 ASW aircraft.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: ASW = Anti-Submarine Warfare, HRC = Hawaii Range Complex, ID CERTEX = Independent Deployer Certification Exercise, NUWTAC = Naval Undersea Warfare
Training Assessment Course, PMSR = Point Mugu Sea Range Overlap, RIMPAC = Rim of the Pacific, SCC = Submarine Commanders Course, SOCAL = Southern
California Range Complex, SWATT = Surface Warfare Advanced Tactical Training, TACDEVEX = Tactical Development Exercise.

Table 3--Proposed Navy Training Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic...................... Major Training Composite Aircraft carrier LFH, MF to HF, 1-2 11 Hawaii, SOCAL,
Exercise--Large Training Unit and carrier air MF1, MFH, MFM. PMSR, NOCAL.
Integrated ASW. Exercise. wing integrates
with surface and
submarine units
in a challenging
multi-threat
operational
environment that
certifies them
ready to deploy.
Duration: 21
days.
Acoustic...................... Major Training Rim of the A biennial HFH, MF1, MFH, 0-1 4 Hawaii, SOCAL.
Exercise--Large Pacific Exercise. multinational MFM.
Integrated ASW. training
exercise in
which navies
from around the
world assemble
in Pearl Harbor,
Hawaii, to
conduct training
throughout the
Hawaiian Islands
in a number of
warfare areas.
Marine mammal
systems may be
used during a
Rim of the
Pacific
exercise.
Components of a
Rim of the
Pacific
exercise, such
as certain mine
warfare and
amphibious
training, may be
conducted in the
Southern
California Range
Complex.
Duration: 30
days.

[[Page 32126]]

Acoustic...................... Major Training Task Force/ Aircraft carrier LFH, MF to HF, 0-1 3 Hawaii.
Exercise--Medium Sustainment and carrier air MF1, MFH, MFM.
Integrated ASW. Exercise. wing integrates
with surface and
submarine units
in a challenging
multi-threat
operational
environment to
maintain ability
to deploy.
Duration: 10
days.
Acoustic...................... Major Training Task Force/ Aircraft carrier LFH, MF to HF, 0-1 3 SOCAL, PMSR,
Exercise--Medium Sustainment and carrier air MF1, MFH, MFM. NOCAL.
Integrated ASW. Exercise. wing integrates
with surface and
submarine units
in a challenging
multi-threat
operational
environment to
maintain ability
to deploy.
Duration: 10
days.
Acoustic...................... Integrated/ Composite Navy and USMC LFH, MF to HF, 1-2 10 Hawaii, SOCAL,
Coordinated ASW. Training Unit forces conduct MF1, MFH, MFM. PMSR, NOCAL.
Exercise--Amphib integration
ious Ready Group/ training at sea
Marine in preparation
Expeditionary for deployment.
Unit. Duration: 3
weeks.
Acoustic...................... Integrated/ Independent Multiple ships, MF to HF, MF1, 8-19 89 SOCAL, PMSR,
Coordinated ASW. Deployer aircraft, and MFH, MFM. NOCAL.
Certification submarines
Exercise/ conduct
Tailored Surface integrated multi-
Warfare Training. warfare training
with a surface
warfare
emphasis. Serves
as a ready-to-
deploy
certification
for individual
surface ships
tasked with
surface warfare
missions.
Duration: 2-3
days.
Acoustic...................... Integrated/ Medium Multiple ships, MF to HF, MF1, 12-17 99 Hawaii.
Coordinated ASW. Coordinated ASW. aircraft, and MFH, MFM.
submarines
integrate the
use of their
sensors,
including
sonobuoys and
unmanned
systems, to
search, detect,
and track threat
submarines;
event may
include inert
torpedo firings.
Duration: 3-10
days.
Acoustic...................... Integrated/ Medium Multiple ships, MF to HF, MF1, 5-13 59 SOCAL, PMSR,
Coordinated ASW. Coordinated ASW. aircraft, and MFH, MFM. NOCAL.
submarines
integrate the
use of their
sensors,
including
sonobuoys and
unmanned
systems, to
search, detect,
and track threat
submarines;
event may
include inert
torpedo firings.
Duration: 3-10
days.
Acoustic...................... Integrated/ Small Joint Typically, a 5- LFH, MF to HF, 1 7 Hawaii.
Coordinated ASW. Coordinated ASW. day exercise MF1, MFH, MFM.
with multiple
ships, aircraft
and submarines
integrating the
use of their
sensors,
including
sonobuoys, to
search, detect,
and track threat
submarines.
Duration: 5 days.
Acoustic...................... Integrated/ Small Joint Typically, a 5- LFH, MF to HF, 4-9 43 SOCAL, PMSR,
Coordinated ASW. Coordinated ASW. day exercise MF1, MFH, MFM. NOCAL.
with multiple
ships, aircraft
and submarines
integrating the
use of their
sensors,
including
sonobuoys, to
search, detect,
and track threat
submarines.
Duration: 5 days.
Explosive..................... Integrated/ Large Amphibious The Large E9............... 0-1 2 Hawaii.
Coordinated Exercise. Amphibious
Training--Other. Exercise
utilizes all
elements of the
Marine Air
Ground Task
Force
(Amphibious) to
secure the
battlespace
(air, land, and
sea), maneuver
to and seize the
objective, and
conduct self-
sustaining
operations
ashore with
logistic support
of the
Expeditionary
Strike Group.
This exercise
could include
manned and
unmanned
activities in
multiple warfare
areas to secure
the battlespace
(air, land, and
sea) and
maneuver and
secure
operations
ashore.
Duration: 1 week.

[[Page 32127]]

Explosive..................... Integrated/ Large Amphibious The Large E9............... 2-4 20 SOCAL, PMSR,
Coordinated Exercise. Amphibious NOCAL.
Training--Other. Exercise
utilizes all
elements of the
Marine Air
Ground Task
Force
(Amphibious) to
secure the
battlespace
(air, land, and
sea), maneuver
to and seize the
objective, and
conduct self-
sustaining
operations
ashore with
logistic support
of the
Expeditionary
Strike Group.
This exercise
could include
manned and
unmanned
activities in
multiple warfare
areas to secure
the battlespace
(air, land, and
sea) and
maneuver and
secure
operations
ashore.
Duration: 1 week.
Acoustic and Explosive........ Integrated/ Innovation and These exercises E5, HFH, LF to 0-1 4 Hawaii.
Coordinated Demonstration are conducted to HF, LFH, MF to
Training--Other. Exercise. demonstrate or HF, MF1, MFH,
test new MFM.
capabilities,
tactics,
techniques, and
procedures; and
generate
standardized,
actionable data
for evaluation.
Duration: 1 week.
Acoustic and Explosive........ Integrated/ Innovation and These exercises E5, HFH, LF to 3 16 SOCAL.
Coordinated Demonstration are conducted to HF, LFH, MF to
Training--Other. Exercise. demonstrate or HF, MF1, MFH,
test new MFM.
capabilities,
tactics,
techniques, and
procedures; and
generate
standardized,
actionable data
for evaluation.
Duration: 1 week.
Acoustic and Explosive........ Integrated/ Innovation and These exercises E5, HFH, LF to 1 7 Transit Corridor.
Coordinated Demonstration are conducted to HF, LFH, MF to
Training--Other. Exercise. demonstrate or HF, MF1, MFH,
test new MFM.
capabilities,
tactics,
techniques, and
procedures; and
generate
standardized,
actionable data
for evaluation.
Duration: 1 week.
Acoustic and Explosive........ Integrated/ Multi-Warfare Live training E5, HFH, LF to 2 12 Hawaii.
Coordinated Exercise. events which HF, LFH, MF to
Training--Other. could involve HF, MF1, MFH,
U.S., Joint, and MFM.
coalition forces
operating across
all warfare
areas (e.g.,
amphibious,
electronic and
cyber, air,
surface, sub-
surface, special
warfare, and
expeditionary)
with manned and
unmanned
platforms.
Events could be
comprised of
small units up
to and including
Carrier and
Amphibious
Strike Groups.
Live-fire events
could be ship-to-
shore, shore-to-
offshore target,
and ship-to-ship
utilizing live
ordnance and
laser systems.
Duration: 1-5
days.
Acoustic and Explosive........ Integrated/ Multi-Warfare Live training E5, HFH, LF to 6-7 43 SOCAL, PMSR.
Coordinated Exercise. events which HF, LFH, MF to
Training--Other. could involve HF, MF1, MFH,
U.S., Joint, and MFM.
coalition forces
operating across
all warfare
areas (e.g.,
amphibious,
electronic and
cyber, air,
surface, sub-
surface, special
warfare, and
expeditionary)
with manned and
unmanned
platforms.
Events could be
comprised of
small units up
to and including
Carrier and
Amphibious
Strike Groups.
Live-fire events
could be ship-to-
shore, shore-to-
offshore target,
and ship-to-ship
utilizing live
ordnance and
laser systems.
Duration: 1-5
days.

[[Page 32128]]

Explosive..................... Amphibious Amphibious Navy and Marine E2............... 15 105 Hawaii.
Warfare. Operations in a Corps forces
Contested conduct
Environment. operations in
coastal and
offshore
waterways
against air,
surface, and
subsurface
threats.
Duration: 1-2
weeks.
Explosive..................... Amphibious Amphibious Navy and Marine E2............... 10 70 SOCAL, SSTC.
Warfare. Operations in a Corps forces
Contested conduct
Environment. operations in
coastal and
offshore
waterways
against air,
surface, and
subsurface
threats.
Duration: 1-2
weeks.
Explosive..................... Amphibious Naval Surface Surface ship E5............... 20-25 155 Hawaii.
Warfare. Fire Support crews fire large-
Exercise-At Sea. caliber guns at
a passive
acoustic
hydrophone
scoring system.
Duration: 1-2
hours of firing,
8 hours total.
Explosive..................... Amphibious Shore-to-Surface Amphibious land- E6............... 1 7 PMRF.
Warfare. Artillery based forces
Exercise. fire artillery
guns at surface
targets.
Duration: 1-2
hours of firing,
8 hours total.
Explosive..................... Amphibious Shore-to-Surface Amphibious land- E6............... 12 84 SCI.
Warfare. Artillery based forces
Exercise. fire artillery
guns at surface
targets.
Duration: 1-2
hours of firing,
8 hours total.
Explosive..................... Amphibious Shore-to-Surface Amphibious land- E9............... 4 28 PMRF.
Warfare. Missile Exercise. based forces
fire anti-
surface
missiles,
rockets, and
loitering
munitions at
surface targets.
Duration: 1-2
hours of firing,
8 hours total.
Explosive..................... Amphibious Shore-to-Surface Amphibious land- E9............... 15 105 SCI.
Warfare. Missile Exercise. based forces
fire anti-
surface
missiles,
rockets, and
loitering
munitions at
surface targets.
Duration: 1-2
hours of firing,
8 hours total.
Acoustic...................... Anti-Submarine Anti-Submarine Helicopter crews HFH, MFH, MFM.... 3-5 27 BARSTUR.
Warfare. Warfare Torpedo search for,
Exercise--Helico track, and
pter. detect
submarines.
Recoverable air
launched
torpedoes are
employed against
submarine
targets.
Duration: 2-5
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Helicopter crews HFH, MFH, MFM.... 3-5 27 SOAR.
Warfare. Warfare Torpedo search for,
Exercise--Helico track, and
pter. detect
submarines.
Recoverable air
launched
torpedoes are
employed against
submarine
targets.
Duration: 2-5
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Maritime patrol HFH, MFM......... 20-80 320 BARSTUR.
Warfare. Warfare Torpedo aircraft
Exercise--Mariti aircrews search
me Patrol for, track, and
Aircraft. detect
submarines.
Recoverable air
launched
torpedoes are
employed against
submarine
targets.
Duration: 2-8
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Maritime patrol HFH, MFM......... 60-80 480 SOAR.
Warfare. Warfare Torpedo aircraft
Exercise--Mariti aircrews search
me Patrol for, track, and
Aircraft. detect
submarines.
Recoverable air
launched
torpedoes are
employed against
submarine
targets.
Duration: 2-8
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Surface ship HFH, MF to HF, 34 238 BARSTUR, BSUR.
Warfare. Warfare Torpedo crews search MF1.
Exercise--Ship. for, track, and
detect
submarines.
Exercise
torpedoes are
used. Duration:
2-5 hours.
Acoustic...................... Anti-Submarine Anti-Submarine Surface ship HFH, MF to HF, 104 728 SOAR.
Warfare. Warfare Torpedo crews search MF1.
Exercise--Ship. for, track, and
detect
submarines.
Exercise
torpedoes are
used. Duration:
2-5 hours.
Acoustic...................... Anti-Submarine Anti-Submarine Submarine crews HFH, LF to HF, 48 336 BARSTUR.
Warfare. Warfare Torpedo search for, MFH.
Exercise--Submar track, and
ine. detect
submarines.
Exercise
torpedoes are
used. Duration:
8 hours.
Acoustic...................... Anti-Submarine Anti-Submarine Submarine crews HFH, LF to HF, 26 182 SOAR.
Warfare. Warfare Torpedo search for, MFH.
Exercise--Submar track, and
ine. detect
submarines.
Exercise
torpedoes are
used. Duration:
8 hours.

[[Page 32129]]

Acoustic...................... Anti-Submarine Anti-Submarine Helicopter crews MFH, MFM......... 125-130 890 Hawaii.
Warfare. Warfare Tracking search for,
Exercise--Helico track, and
pter. detect
submarines.
Duration: 2-4
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Helicopter crews MFH, MFM......... 125-130 890 SOCAL, PMSR.
Warfare. Warfare Tracking search for,
Exercise--Helico track, and
pter. detect
submarines.
Duration: 2-4
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Unmanned surface MFM.............. 5 35 Hawaii.
Warfare. Warfare Tracking vessels search
Exercise--Long- for, detect, and
Range unmanned track a sub-
Surface Vessel. surface target
simulating a
threat submarine
with the goal of
determining a
firing solution
that could be
used to launch a
torpedo.
Duration: 1 day.
Acoustic...................... Anti-Submarine Anti-Submarine Unmanned surface MFM.............. 2 14 SOCAL.
Warfare. Warfare Tracking vessels search
Exercise--Long- for, detect, and
Range unmanned track a sub-
Surface Vessel. surface target
simulating a
threat submarine
with the goal of
determining a
firing solution
that could be
used to launch a
torpedo.
Duration: 1 day.
Acoustic...................... Anti-Submarine Anti-Submarine Maritime patrol LFH, LFM, MFM.... 150-200 1,200 Hawaii.
Warfare. Warfare Tracking aircraft
Exercise--Mariti aircrews search
me Patrol for, track, and
Aircraft. detect
submarines.
Duration: 2-8
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Maritime patrol LFH, LFM, MFM.... 200 1,400 SOCAL, PMSR.
Warfare. Warfare Tracking aircraft
Exercise--Mariti aircrews search
me Patrol for, track, and
Aircraft. detect
submarines.
Duration: 2-8
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Surface ship MF to HF, MF1, 60-119 595 Hawaii.
Warfare. Warfare Tracking crews search MFH.
Exercise--Ship. for, track, and
detect
submarines.
Duration: 2-4
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Surface ship MF to HF, MF1, 240-480 2,400 SOCAL, PMSR.
Warfare. Warfare Tracking crews search MFH.
Exercise--Ship. for, track, and
detect
submarines.
Duration: 2-4
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Submarine crews HFH, MFH......... 200 1,400 Hawaii.
Warfare. Warfare Tracking search for,
Exercise--Submar track, and
ine. detect
submarines.
Duration: 8
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Submarine crews HFH, MFH......... 60 420 SOCAL, PMSR,
Warfare. Warfare Tracking search for, NOCAL.
Exercise--Submar track, and
ine. detect
submarines.
Duration: 8
hours.
Acoustic...................... Anti-Submarine Anti-Submarine Submarine crews HFH, MFH......... 9 63 Transit Corridor.
Warfare. Warfare Tracking search for,
Exercise--Submar track, and
ine. detect
submarines.
Duration: 8
hours.
Acoustic and Explosive........ Anti-Submarine Training and End- A submarine E11, HFH, HFM, 2 14 BARSTUR.
Warfare. to-End Mission launches MFH.
Capability exercise and
Verification--To explosive
rpedo. torpedoes at a
suspended
target.
Duration: 8
hours.
Acoustic and Explosive........ Anti-Submarine Training and End- A submarine E11, HFH, HFM, 1 7 SOAR.
Warfare. to-End Mission launches MFH.
Capability exercise and
Verification--To explosive
rpedo. torpedoes at a
suspended
target.
Duration: 8
hours.
Acoustic...................... Expeditionary Port Damage Navy Pile Driving..... 12 84 Port Hueneme.
Warfare. Repair. Expeditionary
forces train to
repair critical
port facilities.
Duration: 8
hours per day
for 5 days.
Explosive..................... Expeditionary Obstacle Trains forces to E2............... 40 280 FORACS.
Warfare. Clearance. create cleared
lanes in
simulated enemy
obstacle systems
to allow
friendly forces
safe transit
from sea to
shore. Duration:
8 hours.
Explosive..................... Expeditionary Obstacle Trains forces to E2............... 10 70 Lima Landing.
Warfare. Clearance. create cleared
lanes in
simulated enemy
obstacle systems
to allow
friendly forces
safe transit
from sea to
shore. Duration:
8 hours.
Explosive..................... Expeditionary Obstacle Trains forces to E2............... 10 70 Pearl Peninsula.
Warfare. Clearance. create cleared
lanes in
simulated enemy
obstacle systems
to allow
friendly forces
safe transit
from sea to
shore. Duration:
8 hours.
Explosive..................... Expeditionary Obstacle Trains forces to E6............... 10 70 Pu'uloa.
Warfare. Clearance. create cleared
lanes in
simulated enemy
obstacle systems
to allow
friendly forces
safe transit
from sea to
shore. Duration:
8 hours.

[[Page 32130]]

Explosive..................... Expeditionary Obstacle Trains forces to E2............... 100-150 850 SOCAL.
Warfare. Clearance. create cleared
lanes in
simulated enemy
obstacle systems
to allow
friendly forces
safe transit
from sea to
shore. Duration:
8 hours.
Explosive..................... Expeditionary Obstacle Trains forces to E10.............. 6 42 SCI.
Warfare. Clearance. create cleared
lanes in
simulated enemy
obstacle systems
to allow
friendly forces
safe transit
from sea to
shore. Duration:
8 hours.
Explosive..................... Expeditionary Personnel Personnel are E1............... 8 56 FORACS.
Warfare. Insertion/ inserted into a
Extraction--Air. water objective
via fixed-wing
aircraft using
parachutes or by
helicopters via
ropes or jumping
into the water.
Personnel are
extracted by
helicopters or
small boats.
Duration: 1 hour.
Explosive..................... Expeditionary Personnel Personnel are E1............... 26 182 Pearl Peninsula.
Warfare. Insertion/ inserted into a
Extraction--Air. water objective
via fixed-wing
aircraft using
parachutes or by
helicopters via
ropes or jumping
into the water.
Personnel are
extracted by
helicopters or
small boats.
Duration: 1 hour.
Explosive..................... Expeditionary Personnel Personnel are E1............... 500 3,500 Hawaii.
Warfare. Insertion/ inserted into a
Extraction--Air. water objective
via fixed-wing
aircraft using
parachutes or by
helicopters via
ropes or jumping
into the water.
Personnel are
extracted by
helicopters or
small boats.
Duration: 1 hour.
Explosive..................... Expeditionary Personnel Personnel are E1............... 854-954 6,278 SOCAL.
Warfare. Insertion/ inserted into a
Extraction--Air. water objective
via fixed-wing
aircraft using
parachutes or by
helicopters via
ropes or jumping
into the water.
Personnel are
extracted by
helicopters or
small boats.
Duration: 1 hour.
Explosive..................... Expeditionary Personnel Personnel are E1............... 500-600 3,800 SSTC.
Warfare. Insertion/ inserted into a
Extraction--Air. water objective
via fixed-wing
aircraft using
parachutes or by
helicopters via
ropes or jumping
into the water.
Personnel are
extracted by
helicopters or
small boats.
Duration: 1 hour.
Explosive..................... Expeditionary Personnel Personnel are E1............... 270-336 2,088 Hawaii.
Warfare. Insertion/ inserted into
Extraction--Surf and extracted
ace and from an
subsurface. objective area
by small boats
or subsurface
platforms.
Duration: 2-4
hours.
Explosive..................... Expeditionary Personnel Personnel are E1............... 1,049-1,149 7,643 SOCAL.
Warfare. Insertion/ inserted into
Extraction--Surf and extracted
ace and from an
subsurface. objective area
by small boats
or subsurface
platforms.
Duration: 2-4
hours.
Explosive..................... Expeditionary Personnel Divers and E1............... 495 3,465 Hawaii
Warfare. Insertion/ swimmers
Extraction infiltrate
Training--Swimme harbors,
r/Diver. beaches, or
moored vessels
and conduct a
variety of
tasks. Duration:
up to 12 hours.
Explosive..................... Expeditionary Personnel Divers and E1............... 1,080-1,280 8,160 SOCAL.
Warfare. Insertion/ swimmers
Extraction infiltrate
Training--Swimme harbors,
r/Diver. beaches, or
moored vessels
and conduct a
variety of
tasks. Duration:
up to 12 hours.
Explosive..................... Mine Warfare..... Amphibious Amphibious forces E6............... 100 700 Hawaii.
Breaching use explosive
Operations. clearing systems
to clear
simulated mines
on beaches,
shallow water,
and surf zones
for potential
landing of
personnel and
vehicles.
Duration: 8
hours.

[[Page 32131]]

Explosive..................... Mine Warfare..... Amphibious Amphibious forces E6............... 275 1,925 SOCAL.
Breaching use explosive
Operations. clearing systems
to clear
simulated mines
on beaches,
shallow water,
and surf zones
for potential
landing of
personnel and
vehicles.
Duration: 8
hours.
Explosive..................... Mine Warfare..... Amphibious Amphibious forces E6............... 315 2,205 SSTC.
Breaching use explosive
Operations. clearing systems
to clear
simulated mines
on beaches,
shallow water,
and surf zones
for potential
landing of
personnel and
vehicles.
Duration: 8
hours.
Explosive..................... Mine Warfare..... Amphibious Amphibious forces E6............... 48-55 357 SWAT 2.
Breaching use explosive
Operations. clearing systems
to clear
simulated mines
on beaches,
shallow water,
and surf zones
for potential
landing of
personnel and
vehicles.
Duration: 8
hours.
Acoustic and Explosive........ Mine Warfare..... Civilian Port Maritime security E4, HFH, HFM, MFH 1-2 10 Hawaii.
Defense-Homeland personnel train
Security Anti- to protect
Terrorism/Force civilian ports
Protection against enemy
Exercise. efforts to
interfere with
access to those
ports. Duration:
multiple days.
Acoustic and Explosive........ Mine Warfare..... Civilian Port Maritime security E4, HFH, HFM, MFH 1-2 11 SOCAL.
Defense-Homeland personnel train
Security Anti- to protect
Terrorism/Force civilian ports
Protection against enemy
Exercise. efforts to
interfere with
access to those
ports. Duration:
multiple days.
Acoustic and Explosive........ Mine Warfare..... Civilian Port Maritime security E4, HFH, HFM, MFH 1-2 9 PMSR.
Defense-Homeland personnel train
Security Anti- to protect
Terrorism/Force civilian ports
Protection against enemy
Exercise. efforts to
interfere with
access to those
ports. Duration:
multiple days.
Explosive..................... Mine Warfare..... Limpet Mine Navy Explosive E0, E3........... 6-8 48 Lima Landing.
Neutralization Ordnance
System. Disposal divers
place a small
charge on a
simulated
underwater mine.
Duration: 2
hours.
Explosive..................... Mine Warfare..... Limpet Mine Navy Explosive E0, E3........... 138-150 1,002 SOCAL.
Neutralization Ordnance
System. Disposal divers
place a small
charge on a
simulated
underwater mine.
Duration: 2
hours.
Explosive..................... Mine Warfare..... Limpet Mine Navy Explosive E0, E3........... 42-44 300 SSTC.
Neutralization Ordnance
System. Disposal divers
place a small
charge on a
simulated
underwater mine.
Duration: 2
hours.
Acoustic...................... Mine Warfare..... Mine Ship crews detect HFH, MF1K........ 30 210 Hawaii.
Countermeasure and avoid mines
Exercise--Ship while navigating
Sonar. restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic...................... Mine Warfare..... Mine Ship crews detect HFH, MF1K........ 42 294 Pearl Harbor.
Countermeasure and avoid mines
Exercise--Ship while navigating
Sonar. restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic...................... Mine Warfare..... Mine Ship crews detect HFH, MF1K........ 92 644 SOCAL.
Countermeasure and avoid mines
Exercise--Ship while navigating
Sonar. restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic...................... Mine Warfare..... Mine Ship crews detect HFH, MF1K........ 164 1,148 San Diego Bay.
Countermeasure and avoid mines
Exercise--Ship while navigating
Sonar. restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic and Explosive........ Mine Warfare..... Mine Ship, small boat, E4, HFM.......... 7-8 52 Hawaii MTRs.
Countermeasures and helicopter
Mine crews locate and
Neutralization disable mines
Remotely using remotely
Operated Vehicle. operated
underwater
vehicles.
Duration: 1-4
hours.
Acoustic and Explosive........ Mine Warfare..... Mine Ship, small boat, E4, HFM.......... 11 74 SOCAL.
Countermeasures and helicopter
Mine crews locate and
Neutralization disable mines
Remotely using remotely
Operated Vehicle. operated
underwater
vehicles.
Duration: 1-4
hours.

[[Page 32132]]

Acoustic and Explosive........ Mine Warfare..... Mine Ship, small boat, E4, HFM.......... 6 42 SSTC.
Countermeasures and helicopter
Mine crews locate and
Neutralization disable mines
Remotely using remotely
Operated Vehicle. operated
underwater
vehicles.
Duration: 1-4
hours.
Acoustic and Explosive........ Mine Warfare..... Mine Ship, small boat, E4, HFM.......... 3-6 30 TAR 2.
Countermeasures and helicopter
Mine crews locate and
Neutralization disable mines
Remotely using remotely
Operated Vehicle. operated
underwater
vehicles.
Duration: 1-4
hours.
Acoustic and Explosive........ Mine Warfare..... Mine Ship, small boat, E4, HFM.......... 11 74 SCORE.
Countermeasures and helicopter
Mine crews locate and
Neutralization disable mines
Remotely using remotely
Operated Vehicle. operated
underwater
vehicles.
Duration: 1-4
hours.
Explosive..................... Mine Warfare..... Mine Personnel disable E6............... 5-7 41 Hawaii.
Neutralization threat mines
Explosive using explosive
Ordnance charges.
Disposal. Duration: up to
4 hours.
Explosive..................... Mine Warfare..... Mine Personnel disable E6............... 203-211 1,445 SOCAL.
Neutralization threat mines
Explosive using explosive
Ordnance charges.
Disposal. Duration: up to
4 hours.
Explosive..................... Mine Warfare..... Mine Personnel disable E6............... 17-25 143 SSTC.
Neutralization threat mines
Explosive using explosive
Ordnance charges.
Disposal. Duration: up to
4 hours.
Explosive..................... Mine Warfare..... Mine Personnel disable E6............... 0-1 5 SWAT 2.
Neutralization threat mines
Explosive using explosive
Ordnance charges.
Disposal. Duration: up to
4 hours.
Acoustic...................... Mine Warfare..... Submarine Mine Submarine crews HFH, MF to HF, 80 560 Hawaii.
Counter Measure use active sonar VHFH.
Exercise. or UUVs, and
shore-based
personnel
operate UUVs to
detect and avoid
training mine
shapes or other
underwater
hazardous
objects.
Duration: 6
hours.
Acoustic...................... Mine Warfare..... Submarine Mine Submarine crews HFH, MF to HF, 40 280 SOCAL.
Counter Measure use active sonar VHFH.
Exercise. or UUVs, and
shore-based
personnel
operate UUVs to
detect and avoid
training mine
shapes or other
underwater
hazardous
objects.
Duration: 6
hours.
Acoustic...................... Mine Warfare..... Submarine Mobile Submarine crews HFL, HFM, MFM, 20 140 Hawaii.
Mine and Mine and shore-based VHFL.
Laying Exercise. personnel
operating a UUV
deploy exercise
(inert) mobile
mines or mines.
Duration: 6
hours.
Acoustic...................... Mine Warfare..... Submarine Mobile Submarine crews HFL, HFM, MFM, 30 210 SOCAL, PMSR.
Mine and Mine and shore-based VHFL.
Laying Exercise. personnel
operating a UUV
deploy exercise
(inert) mobile
mines or mines.
Duration: 6
hours.
Acoustic...................... Mine Warfare..... Surface Ship Ship crews detect MF1K............. 30 210 Hawaii.
Object Detection. and avoid mines
while navigating
restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic...................... Mine Warfare..... Surface Ship Ship crews detect MF1K............. 42 294 Pearl Harbor.
Object Detection. and avoid mines
while navigating
restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic...................... Mine Warfare..... Surface Ship Ship crews detect MF1K............. 92 644 SOCAL.
Object Detection. and avoid mines
while navigating
restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Acoustic...................... Mine Warfare..... Surface Ship Ship crews detect MF1K............. 164 1,148 San Diego Bay.
Object Detection. and avoid mines
while navigating
restricted areas
or channels
using active
sonar. Duration:
up to 15 hours.
Explosive..................... Mine Warfare..... Underwater Navy divers E5, E6........... 5 35 Pu'uloa, Ewa
Demolition conduct various Beach, Barbers
Qualification levels of Point.
and training and
Certification. certification in
placing
underwater
demolition
charges.
Duration: up to
8 hours.

[[Page 32133]]

Explosive..................... Mine Warfare..... Underwater Navy divers E5, E6........... 10-20 100 TAR 2.
Demolition conduct various
Qualification levels of
and training and
Certification. certification in
placing
underwater
demolition
charges.
Duration: up to
8 hours.
Explosive..................... Mine Warfare..... Underwater Navy divers E5, E6........... 24 168 SSTC.
Demolition conduct various
Qualification levels of
and training and
Certification. certification in
placing
underwater
demolition
charges.
Duration: up to
8 hours.
Explosive..................... Mine Warfare..... Underwater Units deploy E13.............. 6 42 TAR 2.
Demolitions large explosive
Multiple Charge-- systems from
Large Area vessels or
Clearance. vehicles to
destroy barriers
or obstacles
over an area
large enough to
allow amphibious
vehicles to
access beach
areas. Duration:
4 hours.
Explosive..................... Surface Warfare.. Bombing Exercise Fixed-wing E9, E10, E12..... 194 1,358 Hawaii.
Air-to-Surface. aircrews deliver
bombs against
surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Bombing Exercise Fixed-wing E9, E10, E12..... 653 4,571 SOCAL.
Air-to-Surface. aircrews deliver
bombs against
surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Bombing Exercise Fixed-wing E9, E10, E12..... 10 70 NOCAL.
Air-to-Surface. aircrews deliver
bombs against
surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Gunnery Exercise Small boat crews E1............... 10 70 Hawaii.
Surface-to- fire medium-
Surface Boat caliber guns at
Medium-Caliber. surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Gunnery Exercise Small boat crews E1............... 14 98 SOCAL.
Surface-to- fire medium-
Surface Boat caliber guns at
Medium-Caliber. surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Gunnery Exercise Surface ship E3, E5........... 32 224 Hawaii.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-Caliber. surface targets.
Duration: up to
3 hours.
Explosive..................... Surface Warfare.. Gunnery Exercise Surface ship E3, E5........... 125 875 SOCAL.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-Caliber. surface targets.
Duration: up to
3 hours.
Explosive..................... Surface Warfare.. Gunnery Exercise Surface ship E3, E5........... 14 98 Transit Corridor.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-Caliber. surface targets.
Duration: up to
3 hours.
Explosive..................... Surface Warfare.. Gunnery Exercise Surface ship E1............... 5-50 170 Hawaii.
Surface-to- crews fire
Surface Ship medium-caliber
Medium-Caliber. guns at surface
targets.
Duration: 2-3
hours.
Explosive..................... Surface Warfare.. Gunnery Exercise Surface ship E1............... 17-180 608 SOCAL.
Surface-to- crews fire
Surface Ship medium-caliber
Medium-Caliber. guns at surface
targets.
Duration: 2-3
hours.
Explosive..................... Surface Warfare.. Gunnery Exercise Surface ship E1............... 6-40 144 Transit Corridor.
Surface-to- crews fire
Surface Ship medium-caliber
Medium-Caliber. guns at surface
targets.
Duration: 2-3
hours.
Explosive..................... Surface Warfare.. Missile Exercise Fixed-wing and E6, E7, E8, E9... 17-22 134 Hawaii.
Air-to-Surface. helicopter
aircrews fire
air-to-surface
missiles at
surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Missile Exercise Fixed-wing and E6, E7, E8, E9... 4-9 43 SOCAL.
Air-to-Surface. helicopter
aircrews fire
air-to-surface
missiles at
surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Missile Exercise Fixed-wing and E6, E7, E8, E9... 90 630 PMSR.
Air-to-Surface. helicopter
aircrews fire
air-to-surface
missiles at
surface targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Missile Exercise Helicopter E3............... 109-129 823 Hawaii.
Air-to-Surface aircrews fire
Rocket. both precision-
guided and
unguided rockets
at surface
targets.
Duration: 1 hour.
Explosive..................... Surface Warfare.. Missile Exercise Helicopter E3............... 251-271 1,817 SOCAL.
Air-to-Surface aircrews fire
Rocket. both precision-
guided and
unguided rockets
at surface
targets.
Duration: 1 hour.

[[Page 32134]]

Explosive..................... Surface Warfare.. Missile Exercise Surface ship E9............... 28-32 208 Hawaii.
Surface-to- crews defend
Surface. against surface
threats (ships
or small boats)
and engage them
with missiles.
Duration: 2-5
hours.
Explosive..................... Surface Warfare.. Missile Exercise Surface ship E9............... 10 70 SOCAL.
Surface-to- crews defend
Surface. against surface
threats (ships
or small boats)
and engage them
with missiles.
Duration: 2-5
hours.
Explosive..................... Surface Warfare.. Sinking Exercise. Aircraft, ship, E5, E8, E9, E11, 2-3 17 Hawaii.
and submarine E12.
crews
deliberately
sink a seaborne
target, usually
a decommissioned
ship made
environmentally
safe for sinking
according to
U.S.
Environmental
Protection
Agency
standards, with
a variety of
ordnance.
Duration: 4-8
hours.
Explosive..................... Surface Warfare.. Sinking Exercise. Aircraft, ship, E5, E8, E9, E11, 0-1 3 SOCAL.
and submarine E12.
crews
deliberately
sink a seaborne
target, usually
a decommissioned
ship made
environmentally
safe for sinking
according to
U.S.
Environmental
Protection
Agency
standards, with
a variety of
ordnance.
Duration: 4-8
hours.
Acoustic...................... Surface Warfare.. Surface Warfare Submarine crews HFH.............. 30 210 Hawaii.
Torpedo search for,
Exercise--Submar detect, and
ine. track a surface
ship simulating
a threat surface
ship with the
goal of
determining a
firing solution
that could be
used to launch a
torpedo with the
intent to
simulate
destroying the
targets.
Duration: 8
hours.
Acoustic...................... Surface Warfare.. Surface Warfare Submarine crews HFH.............. 10 70 SOCAL.
Torpedo search for,
Exercise--Submar detect, and
ine. track a surface
ship simulating
a threat surface
ship with the
goal of
determining a
firing solution
that could be
used to launch a
torpedo with the
intent to
simulate
destroying the
targets.
Duration: 8
hours.
Explosive..................... Surface Warfare.. Training and End- Submarine crews E9, E10.......... 2 14 Hawaii.
to-End Mission launch
Capability missile(s) which
Verification--Su may have an
bmarine Missile explosive
Maritime. warhead at a
maritime target
simulating an
adversary
surface ship
with the goal of
destroying or
disabling
adversary
surface ship.
Duration: 8
hours.
Explosive..................... Surface Warfare.. Training and End- Submarine crews E9, E10.......... 3 21 SOCAL.
to-End Mission launch
Capability missile(s) which
Verification--Su may have an
bmarine Missile explosive
Maritime. warhead at a
maritime target
simulating an
adversary
surface ship
with the goal of
destroying or
disabling
adversary
surface ship.
Duration: 8
hours.
Acoustic and Explosive........ Other Training Multi-Domain Multi-domain E5, E7, MF to HF, 50-100 500 Hawaii.
Activities. Unmanned (surface, VHFH.
Autonomous subsurface, and
Systems. airborne)
unmanned
autonomous
systems are
launched from
land, ships, and
boats, in
support of
intelligence,
surveillance,
and
reconnaissance
operations; and
deliver
munitions or
other non-
munition systems
to support
mission and
intelligence
requirements.
Duration: 4-8
hours.

[[Page 32135]]

Acoustic and Explosive........ Other Training Multi-Domain Multi-domain E5, E7, MF to HF, 55-105 535 Pyramid Cove,
Activities. Unmanned (surface, VHFH. SWATs.
Autonomous subsurface, and
Systems. airborne)
unmanned
autonomous
systems are
launched from
land, ships, and
boats, in
support of
intelligence,
surveillance,
and
reconnaissance
operations; and
deliver
munitions or
other non-
munition systems
to support
mission and
intelligence
requirements.
Duration: 4-8
hours.
Acoustic and Explosive........ Other Training Multi-Domain Multi-domain E5, E7, MF to HF, 50-100 500 SOCAL.
Activities. Unmanned (surface, VHFH.
Autonomous subsurface, and
Systems. airborne)
unmanned
autonomous
systems are
launched from
land, ships, and
boats, in
support of
intelligence,
surveillance,
and
reconnaissance
operations; and
deliver
munitions or
other non-
munition systems
to support
mission and
intelligence
requirements.
Duration: 4-8
hours.
Acoustic...................... Other Training Submarine Submarine crews HFH, MFH......... 220 1,540 Pearl Harbor.
Activities. Navigation operate sonar
Exercise. for navigation
and object
detection while
transiting into
and out of port
during reduced
visibility.
Duration: 2
hours.
Acoustic...................... Other Training Submarine Submarine crews HFH, MFH......... 80 560 San Diego Bay.
Activities. Navigation operate sonar
Exercise. for navigation
and object
detection while
transiting into
and out of port
during reduced
visibility.
Duration: 2
hours.
Acoustic...................... Other Training Submarine Sonar Maintenance of MFH.............. 260 1,820 Hawaii.
Activities. Maintenance and submarine sonar
Systems Checks. systems is
conducted
pierside or at
sea. Duration: 1
hour.
Acoustic...................... Other Training Submarine Sonar Maintenance of MFH.............. 260 1,820 Pearl Harbor.
Activities. Maintenance and submarine sonar
Systems Checks. systems is
conducted
pierside or at
sea. Duration: 1
hour.
Acoustic...................... Other Training Submarine Sonar Maintenance of MFH.............. 80 560 SOCAL.
Activities. Maintenance and submarine sonar
Systems Checks. systems is
conducted
pierside or at
sea. Duration: 1
hour.
Acoustic...................... Other Training Submarine Sonar Maintenance of MFH.............. 13 91 PMSR.
Activities. Maintenance and submarine sonar
Systems Checks. systems is
conducted
pierside or at
sea. Duration: 1
hour.
Acoustic...................... Other Training Submarine Sonar Maintenance of MFH.............. 92 644 San Diego Bay.
Activities. Maintenance and submarine sonar
Systems Checks. systems is
conducted
pierside or at
sea. Duration: 1
hour.
Acoustic...................... Other Training Submarine Sonar Maintenance of MFH.............. 10 70 Transit Corridor.
Activities. Maintenance and submarine sonar
Systems Checks. systems is
conducted
pierside or at
sea. Duration: 1
hour.
Acoustic...................... Other Training Submarine Under Submarine crews HFH.............. 12 84 Hawaii.
Activities. Ice Training and train to operate
Certification. under ice. Ice
conditions are
simulated during
training and
certification
events.
Duration: 5 days.
Acoustic...................... Other Training Submarine Under Submarine crews HFH.............. 6 42 SOCAL.
Activities. Ice Training and train to operate
Certification. under ice. Ice
conditions are
simulated during
training and
certification
events.
Duration: 5 days.

[[Page 32136]]

Acoustic and Explosive........ Other Training Submarine and UUV Submarine crews E3, VHFH......... 20 140 Hawaii.
Activities. Subsea and and shore-based
Seabed Warfare operators train
Exercise. to launch or
recover and
operate all
classes of UUVs
in the subsea
and seabed
environment in
order to defend
deep ocean and
seabed
infrastructure
or take
offensive action
against a
simulated
adversary's
subsea and
seabed
infrastructure.
Duration: 1 day.
Acoustic and Explosive........ Other Training Submarine and UUV Submarine crews E3, VHFH......... 10 70 SOCAL.
Activities. Subsea and and shore-based
Seabed Warfare operators train
Exercise. to launch or
recover and
operate all
classes of UUVs
in the subsea
and seabed
environment in
order to defend
deep ocean and
seabed
infrastructure
or take
offensive action
against a
simulated
adversary's
subsea and
seabed
infrastructure.
Duration: 1 day.
Acoustic and Explosive........ Other Training Submarine and UUV Submarine crews E3, VHFH......... 5 35 PMSR.
Activities. Subsea and and shore-based
Seabed Warfare operators train
Exercise. to launch or
recover and
operate all
classes of UUVs
in the subsea
and seabed
environment in
order to defend
deep ocean and
seabed
infrastructure
or take
offensive action
against a
simulated
adversary's
subsea and
seabed
infrastructure.
Duration: 1 day.
Acoustic and Explosive........ Other Training Submarine and UUV Submarine crews E3, VHFH......... 5 35 NOCAL.
Activities. Subsea and and shore-based
Seabed Warfare operators train
Exercise. to launch or
recover and
operate all
classes of UUVs
in the subsea
and seabed
environment in
order to defend
deep ocean and
seabed
infrastructure
or take
offensive action
against a
simulated
adversary's
subsea and
seabed
infrastructure.
Duration: 1 day.
Acoustic...................... Other Training Surface Ship Maintenance of HFH, MF1, MF1K, 75 525 Hawaii.
Activities. Sonar surface ship MFH.
Maintenance and sonar systems is
Systems Checks. conducted
pierside or at
sea. Duration: 4
hours.
Acoustic...................... Other Training Surface Ship Maintenance of HFH, MF1, MF1K, 80 560 Pearl Harbor.
Activities. Sonar surface ship MFH.
Maintenance and sonar systems is
Systems Checks. conducted
pierside or at
sea. Duration: 4
hours.
Acoustic...................... Other Training Surface Ship Maintenance of HFH, MF1, MF1K, 250 1,750 SOCAL.
Activities. Sonar surface ship MFH.
Maintenance and sonar systems is
Systems Checks. conducted
pierside or at
sea. Duration: 4
hours.
Acoustic...................... Other Training Surface Ship Maintenance of HFH, MF1, MF1K, 250 1,750 San Diego Bay.
Activities. Sonar surface ship MFH.
Maintenance and sonar systems is
Systems Checks. conducted
pierside or at
sea. Duration: 4
hours.
Acoustic...................... Other Training Surface Ship Maintenance of HFH, MF1, MF1K, 8-12 68 Transit Corridor.
Activities. Sonar surface ship MFH.
Maintenance and sonar systems is
Systems Checks. conducted
pierside or at
sea. Duration: 4
hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 20 140 Hawaii.
Activities. to-End Mission or shore-based
Capability operators employ
Verification--Su UUV with
bsea and Seabed munitions or non-
Warfare Kinetic munition systems
Effectors. on the sea floor
or in the water
column.
Duration: 8
hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 10 70 SOCAL.
Activities. to-End Mission or shore-based
Capability operators employ
Verification--Su UUV with
bsea and Seabed munitions or non-
Warfare Kinetic munition systems
Effectors. on the sea floor
or in the water
column.
Duration: 8
hours.

[[Page 32137]]

Explosive..................... Other Training Training and End- Submarine crews E3............... 5 35 PMSR.
Activities. to-End Mission or shore-based
Capability operators employ
Verification--Su UUV with
bsea and Seabed munitions or non-
Warfare Kinetic munition systems
Effectors. on the sea floor
or in the water
column.
Duration: 8
hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 5 35 NOCAL.
Activities. to-End Mission or shore-based
Capability operators employ
Verification--Su UUV with
bsea and Seabed munitions or non-
Warfare Kinetic munition systems
Effectors. on the sea floor
or in the water
column.
Duration: 8
hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 10 70 Hawaii.
Activities. to-End Mission or shore-based
Capability personnel
Verification--Un controlling a
manned Aerial UUV launch a
Vehicle (UAV). capsule
containing a
UAV. The
canister is
deployed
underwater and
ascends to a
programmed
depth. The
canister
subsequently
launches a UAV,
and the canister
sinks. Duration:
8 hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 5 35 SOCAL.
Activities. to-End Mission or shore-based
Capability personnel
Verification--Un controlling a
manned Aerial UUV launch a
Vehicle (UAV). capsule
containing a
UAV. The
canister is
deployed
underwater and
ascends to a
programmed
depth. The
canister
subsequently
launches a UAV,
and the canister
sinks. Duration:
8 hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 3 21 PMSR.
Activities. to-End Mission or shore-based
Capability personnel
Verification--Un controlling a
manned Aerial UUV launch a
Vehicle (UAV). capsule
containing a
UAV. The
canister is
deployed
underwater and
ascends to a
programmed
depth. The
canister
subsequently
launches a UAV,
and the canister
sinks. Duration:
8 hours.
Explosive..................... Other Training Training and End- Submarine crews E3............... 2 14 NOCAL.
Activities. to-End Mission or shore-based
Capability personnel
Verification--Un controlling a
manned Aerial UUV launch a
Vehicle (UAV). capsule
containing a
UAV. The
canister is
deployed
underwater and
ascends to a
programmed
depth. The
canister
subsequently
launches a UAV,
and the canister
sinks. Duration:
8 hours.
Acoustic...................... Other Training Unmanned Unmanned HFM, MF to HF, 82-178 862 Hawaii.
Activities. Underwater underwater VHFH.
Vehicle vehicle
Training--Certif certification
ication and involves
Development training with
Exercises. unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.
Acoustic...................... Other Training Unmanned Unmanned HFM, MF to HF, 284-492 2,612 SOCAL.
Activities. Underwater underwater VHFH.
Vehicle vehicle
Training--Certif certification
ication and involves
Development training with
Exercises. unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.

[[Page 32138]]

Acoustic...................... Other Training Unmanned Unmanned HFM, MF to HF, 130-260 1,300 SSTC.
Activities. Underwater underwater VHFH.
Vehicle vehicle
Training--Certif certification
ication and involves
Development training with
Exercises. unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.
Acoustic...................... Other Training Unmanned Unmanned HFM, MF to HF, 18-36 180 China Point.
Activities. Underwater underwater VHFH.
Vehicle vehicle
Training--Certif certification
ication and involves
Development training with
Exercises. unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low-frequency, MF = mid-frequency, HF = high-frequency, dB = decibels, L = low, M= medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count. BARSTUR = Barking Sands Tactical Underwater Range, FORACS = Fleet Operational Readiness Accuracy Check Site, Hawaii =
the Hawaii Study Area, MTR = Mine Training Range, NOCAL = Northern California Range Complex, PMRF = Pacific Missile Range Facility, PMSR = Point Mugu
Sea Range, SCI = San Clemente Island, SOAR = Southern California Offshore Anti-Submarine Warfare Range, SOCAL = Southern California Range Complex,
SSTC = Silver Strand Training Complex, SWAT = Special Warfare Training Area, TAR = Training Area and Range.

Table 4--Proposed Coast Guard Training Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Explosive...................... Surface Warfare... Gunnery Exercise Surface ship E3............... 5 35 Hawaii.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-caliber. surface targets.
Duration: up to
3 hours.
Explosive...................... Surface Warfare... Gunnery Exercise Surface ship E3............... 20 140 SOCAL.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-caliber. surface targets.
Duration: up to
3 hours.
Explosive...................... Surface Warfare... Gunnery Exercise Surface ship E3............... 2 14 PMSR.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-caliber. surface targets.
Duration: up to
3 hours.
Explosive...................... Surface Warfare... Gunnery Exercise Surface ship E3............... 2 14 NOCAL.
Surface-to- crews fire large-
Surface Ship caliber guns at
Large-caliber. surface targets.
Duration: up to
3 hours.
Acoustic....................... Other Training.... Unmanned Unmanned HFM, MF to HF, 200 1,400 Hawaii.
Underwater underwater VHFH.
Vehicle Training-- vehicle
Certification and certification
Development involves
Exercises. training with
unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.
Acoustic....................... Other Training.... Unmanned Unmanned HFM, MF to HF, 200 1,400 SOCAL.
Underwater underwater VHFH.
Vehicle Training-- vehicle
Certification and certification
Development involves
Exercises. training with
unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.
Acoustic....................... Other Training.... Unmanned Unmanned HFM, MF to HF, 100 700 PMSR.
Underwater underwater VHFH.
Vehicle Training-- vehicle
Certification and certification
Development involves
Exercises. training with
unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.

[[Page 32139]]

Acoustic....................... Other Training.... Unmanned Unmanned HFM, MF to HF, 10 70 NOCAL.
Underwater underwater VHFH.
Vehicle Training-- vehicle
Certification and certification
Development involves
Exercises. training with
unmanned
platforms to
ensure submarine
crew
proficiency.
Tactical
development
involves
training with
various payloads
for multiple
purposes to
ensure that the
systems can be
employed
effectively in
an operational
environment.
Duration: up to
24 hours.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low-frequency, MF = mid-frequency, HF = high-frequency, dB = decibels, L = low, M = medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count. Hawaii = the Hawaii Study Area, NOCAL = Northern California Range Complex, PMSR = Point Mugu Sea Range, SOCAL = Southern
California Range Complex.

Table 5--Proposed Army Training Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Explosive...................... Amphibious Warfare Shore-to-Surface Amphibious land- E6............... 2 14 PMRF.
Artillery based forces
Exercise. fire artillery
guns at surface
targets.
Duration: 1-2
hours of firing,
8 hours total.
Explosive...................... Amphibious Warfare Shore-to-Surface Amphibious land- E9............... 18 126 PMRF.
Missile Exercise. based forces
fire anti-
surface
missiles,
rockets, and
loitering
munitions at
surface targets.
Duration: 1-2
hours of firing,
8 hours total.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: PMRF = Pacific Missile Range Facility.

Overview of Testing Activities Within the Study Area
While this proposed rule includes an evaluation of proposed
training activities by the Navy, Coast Guard, and Army, all testing
activities evaluated in this proposed rule would only be conducted by
the Navy. The Navy's research and acquisition community engages in a
broad spectrum of testing activities, some of which ultimately support
all Action Proponents. These activities include, but are not limited
to, basic and applied scientific research and technology development;
testing, evaluation, and maintenance of systems (e.g., missiles, radar,
and sonar) and platforms (e.g., surface ships, submarines, and
aircraft); and acquisition of systems and platforms to support Navy
missions and give a technological edge over adversaries. The individual
commands within the research and acquisition community considered in
the application are Naval Air Systems Command (NAVAIR), Naval
Facilities Engineering and Expeditionary Warfare Center, Naval Sea
Systems Command (NAVSEA), Office of Naval Research (ONR), and Naval
Information Warfare Systems Command (NAVWAR). Although included in the
testing community, proposed Expeditionary Warfare Center activities do
not involve sonar and other transducers, underwater detonations, pile
driving, airguns, or any other stressors that could result in
harassment of marine mammals, and therefore, are not analyzed further
in this proposed rule.
The Action Proponents operate in an ever-changing strategic,
tactical, financially-constrained, and time-constrained environment.
Testing activities occur in response to emerging science or fleet
operational needs. For example, future Navy studies to develop a better
understanding of ocean currents may be designed based on advancements
made by non-government researchers not yet published in the scientific
literature. Similarly, future but yet unknown Navy, Coast Guard, and
Army operations within a specific geographic area may require
development of modified Navy assets to address local conditions. Such
modifications must be tested in the field to ensure they meet fleet
needs and requirements. Accordingly, generic descriptions of some of
these activities are the best that can be articulated in a long-term,
comprehensive document.
Some testing activities are similar to training activities
conducted by the fleet (e.g., both the fleet and the research and
acquisition community fire torpedoes). While the firing of a torpedo
might look identical to an observer, the difference is in the purpose
of the firing. The fleet might fire the torpedo to practice the
procedures for such a firing, whereas the research and acquisition
community might be assessing a new torpedo guidance technology or
testing it to ensure the torpedo meets performance specifications and
operational requirements (see appendix A (Activity Descriptions) of the
2024 HCTT Draft EIS/OEIS for more detailed descriptions of the
activities).
NAVAIR testing activities generally fall in the primary mission
areas used by the fleets and include the evaluation of new and in-
service aircraft platforms and systems to deliver critical air warfare
capabilities to the fleets. To accomplish its mission, NAVAIR conducts
anti-submarine warfare tests using fixed-wing and rotary wing aircraft
platforms, a suite of passive and active acoustic sonobuoys (to include
Lot Acceptance Testing), and dipping sonar systems.
The majority of testing activities conducted by NAVAIR are similar
to fleet training activities, and many platforms and systems currently
being tested are already being used by the fleet or will ultimately be
integrated into fleet training activities. However, some testing
activities may be conducted in different locations and in a different
manner than similar fleet training activities, and, therefore, the
analysis for those events and the potential environmental effects may
differ. Table 6 summarizes the proposed testing

[[Page 32140]]

activities for NAVAIR analyzed within the HCTT Study Area.

Table 6--Proposed NAVAIR Testing Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic....................... Anti-Submarine ASW Torpedo Test-- This event is HFH, MFH, MFM.... 24-26 174 Hawaii.
Warfare. Aircraft. similar to the
training event
torpedo
exercise. Test
evaluates anti-
submarine
warfare systems
onboard rotary-
wing and fixed-
wing aircraft
and the ability
to search for,
detect,
classify,
localize, track,
and attack a
submarine or
similar target.
Duration: 2-6
hours.
Acoustic....................... Anti-Submarine ASW Torpedo Test-- This event is HFH, MFH, MFM.... 36-39 259 SOCAL.
Warfare. Aircraft. similar to the
training event
torpedo
exercise. Test
evaluates anti-
submarine
warfare systems
onboard rotary-
wing and fixed-
wing aircraft
and the ability
to search for,
detect,
classify,
localize, track,
and attack a
submarine or
similar target.
Duration: 2-6
hours.
Acoustic....................... Anti-Submarine ASW Torpedo Test-- This event is HFH, MFH, MFM.... 36-39 259 SCORE.
Warfare. Aircraft. similar to the
training event
torpedo
exercise. Test
evaluates anti-
submarine
warfare systems
onboard rotary-
wing and fixed-
wing aircraft
and the ability
to search for,
detect,
classify,
localize, track,
and attack a
submarine or
similar target.
Duration: 2-6
hours.
Acoustic....................... Anti-Submarine ASW Tracking Test-- The test HFM, LFH, LFM, 61-67 445 Hawaii.
Warfare. Fixed-Wing. evaluates the MFM.
sensors and
systems used by
maritime patrol
aircraft to
detect and track
submarines and
to ensure that
aircraft systems
used to deploy
the tracking
systems perform
to
specifications
and meet
operational
requirements.
Duration: 8
hours.
Acoustic....................... Anti-Submarine ASW Tracking Test-- The test HFM, LFH, LFM, 68-75 497 SOCAL.
Warfare. Fixed-Wing. evaluates the MFM.
sensors and
systems used by
maritime patrol
aircraft to
detect and track
submarines and
to ensure that
aircraft systems
used to deploy
the tracking
systems perform
to
specifications
and meet
operational
requirements.
Duration: 8
hours.
Acoustic....................... Anti-Submarine ASW Tracking Test-- The test MFH, MFM......... 66-73 483 Hawaii.
Warfare. Rotary Wing. evaluates the
sensors and
systems used by
helicopters to
detect and track
submarines and
to ensure that
aircraft systems
used to deploy
the tracking
systems perform
to
specifications
and meet
operational
requirements.
Duration: 2
hours.
Acoustic....................... Anti-Submarine ASW Tracking Test-- The test MFH, MFM......... 66-73 482 SOCAL.
Warfare. Rotary Wing. evaluates the
sensors and
systems used by
helicopters to
detect and track
submarines and
to ensure that
aircraft systems
used to deploy
the tracking
systems perform
to
specifications
and meet
operational
requirements.
Duration: 2
hours.
Acoustic....................... Anti-Submarine ASW Tracking Test-- The test MFH, MFM......... 66-73 482 SCORE.
Warfare. Rotary Wing. evaluates the
sensors and
systems used by
helicopters to
detect and track
submarines and
to ensure that
aircraft systems
used to deploy
the tracking
systems perform
to
specifications
and meet
operational
requirements.
Duration: 2
hours.
Acoustic....................... Anti-Submarine Kilo Dip Test..... Functional check MFH.............. 6-7 45 Hawaii.
Warfare. of a helicopter-
deployed dipping
sonar system
prior to
conducting a
testing or
training event
using the
dipping sonar
system.
Duration: 1-2
hours.

[[Page 32141]]

Acoustic....................... Anti-Submarine Kilo Dip Test..... Functional check MFH.............. 6-7 45 SOCAL.
Warfare. of a helicopter-
deployed dipping
sonar system
prior to
conducting a
testing or
training event
using the
dipping sonar
system.
Duration: 1-2
hours.
Acoustic....................... Anti-Submarine Sonobuoy Lot Sonobuoys are HFM, LFH, LFM, 32-38 242 Hawaii.
Warfare. Acceptance Test. deployed from MFM.
surface vessels
and aircraft to
verify the
integrity and
performance of a
lot or group of
sonobuoys in
advance of
delivery to the
fleet for
operational use.
Duration: 6
hours.
Acoustic....................... Anti-Submarine Sonobuoy Lot Sonobuoys are HFM, LFH, LFM, 320-352 2,336 SOCAL.
Warfare. Acceptance Test. deployed from MFM.
surface vessels
and aircraft to
verify the
integrity and
performance of a
lot or group of
sonobuoys in
advance of
delivery to the
fleet for
operational use.
Duration: 6
hours.
Acoustic....................... Mine Warfare...... Airborne Dipping A mine-hunting HFH.............. 18-20 132 Hawaii.
Sonar Minehunting dipping sonar
Test. system that is
deployed from a
helicopter and
uses high-
frequency sonar
for the
detection and
classification
of bottom and
moored mines.
Duration: 2
hours.
Acoustic....................... Mine Warfare...... Airborne Dipping A mine-hunting HFH.............. 18-20 132 SOCAL.
Sonar Minehunting dipping sonar
Test. system that is
deployed from a
helicopter and
uses high-
frequency sonar
for the
detection and
classification
of bottom and
moored mines.
Duration: 2
hours.
Explosive...................... Mine Warfare...... Airborne Mine A test of the E4............... 36-39 261 Hawaii.
Neutralization airborne mine
System Test. neutralization
system evaluates
the system's
ability to
detect and
destroy mines
from an airborne
mine
countermeasures
capable
helicopter. The
Airborne Mine
Neutralization
System uses up
to four unmanned
underwater
vehicles
equipped with
high frequency
sonar, video
cameras, and
explosive and
non-explosive
neutralizers.
Duration: 2-3
hours.
Explosive...................... Mine Warfare...... Airborne Mine A test of the E4............... 81-84 576 SOCAL.
Neutralization airborne mine
System Test. neutralization
system evaluates
the system's
ability to
detect and
destroy mines
from an airborne
mine
countermeasures
capable
helicopter. The
Airborne Mine
Neutralization
System uses up
to four unmanned
underwater
vehicles
equipped with
high frequency
sonar, video
cameras, and
explosive and
non-explosive
neutralizers.
Duration: 2-3
hours.
Acoustic....................... Mine Warfare...... Airborne Sonobuoy A mine-hunting MFM.............. 9-10 66 Hawaii.
Minehunting Test. system made up
of sonobuoys
deployed from a
helicopter. A
field of
sonobuoys, using
high-frequency
sonar, is used
to detect and
classify bottom
and moored
mines. Duration:
2 hours.
Acoustic....................... Mine Warfare...... Airborne Sonobuoy A mine-hunting MFM.............. 9-10 66 SOCAL.
Minehunting Test. system made up
of sonobuoys
deployed from a
helicopter. A
field of
sonobuoys, using
high-frequency
sonar, is used
to detect and
classify bottom
and moored
mines. Duration:
2 hours.

[[Page 32142]]

Explosive...................... Surface Warfare... Air-to-Surface This event is E7, E9........... 8-9 59 Hawaii.
Bombing Test. similar to the
training event
bombing exercise
air-to-surface.
Fixed-wing
aircraft test
the delivery of
bombs against
surface maritime
targets with the
goal of
evaluating the
bomb, the bomb
carry and
delivery system,
and any
associated
systems that may
have been newly
developed or
enhanced.
Duration: 2
hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E7, E9........... 14-15 101 SOCAL.
Bombing Test. similar to the
training event
bombing exercise
air-to-surface.
Fixed-wing
aircraft test
the delivery of
bombs against
surface maritime
targets with the
goal of
evaluating the
bomb, the bomb
carry and
delivery system,
and any
associated
systems that may
have been newly
developed or
enhanced.
Duration: 2
hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E7, E9........... 52 364 PMSR.
Bombing Test. similar to the
training event
bombing exercise
air-to-surface.
Fixed-wing
aircraft test
the delivery of
bombs against
surface maritime
targets with the
goal of
evaluating the
bomb, the bomb
carry and
delivery system,
and any
associated
systems that may
have been newly
developed or
enhanced.
Duration: 2
hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E1............... 6-7 45 Hawaii.
Gunnery Test. similar to the
training event
gunnery exercise
(air to
surface). Fixed-
wing and rotary-
wing aircrews
evaluate new or
enhanced
aircraft guns
against surface
maritime targets
to test that the
gun, gun
ammunition, or
associated
systems meet
required
specifications
or to train
aircrew in the
operation of a
new or enhanced
weapon system.
Duration: 2-3
hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E1............... 60-66 438 SOCAL.
Gunnery Test. similar to the
training event
gunnery exercise
(air to
surface). Fixed-
wing and rotary-
wing aircrews
evaluate new or
enhanced
aircraft guns
against surface
maritime targets
to test that the
gun, gun
ammunition, or
associated
systems meet
required
specifications
or to train
aircrew in the
operation of a
new or enhanced
weapon system.
Duration: 2-3
hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E1............... 10 70 PMSR.
Gunnery Test. similar to the
training event
gunnery exercise
(air to
surface). Fixed-
wing and rotary-
wing aircrews
evaluate new or
enhanced
aircraft guns
against surface
maritime targets
to test that the
gun, gun
ammunition, or
associated
systems meet
required
specifications
or to train
aircrew in the
operation of a
new or enhanced
weapon system.
Duration: 2-3
hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E6, E7, E8, E9... 18-20 132 Hawaii.
Missile Test. similar to the
training event
missile exercise
air-to-surface.
Test may involve
both fixed-wing
and rotary-wing
aircraft
launching
missiles at
surface maritime
targets to
evaluate the
weapons system
or as part of
another system's
integration
test. Duration:
2-4 hours.

[[Page 32143]]

Explosive...................... Surface Warfare... Air-to-Surface This event is E6, E7, E8, E9... 8 56 SOCAL.
Missile Test. similar to the
training event
missile exercise
air-to-surface.
Test may involve
both fixed-wing
and rotary-wing
aircraft
launching
missiles at
surface maritime
targets to
evaluate the
weapons system
or as part of
another system's
integration
test. Duration:
2-4 hours.
Explosive...................... Surface Warfare... Air-to-Surface This event is E6, E7, E8, E9... 180-186 1,275 PMSR.
Missile Test. similar to the
training event
missile exercise
air-to-surface.
Test may involve
both fixed-wing
and rotary-wing
aircraft
launching
missiles at
surface maritime
targets to
evaluate the
weapons system
or as part of
another system's
integration
test. Duration:
2-4 hours.
Explosive...................... Surface Warfare... Rocket Test....... Rocket tests E3, E9........... 2 14 Hawaii.
evaluate the
integration,
accuracy,
performance, and
safe separation
of guided and
unguided 2.75-
inch (7
centimeter (cm))
rockets fired
from a hovering
or forward
flying
helicopter.
Duration: 1-3
hours.
Explosive...................... Surface Warfare... Rocket Test....... Rocket tests E3, E9........... 22-24 160 SOCAL.
evaluate the
integration,
accuracy,
performance, and
safe separation
of guided and
unguided 2.75-
inch (7 cm)
rockets fired
from a hovering
or forward
flying
helicopter.
Duration: 1-3
hours.
Explosive...................... Surface Warfare... Rocket Test....... Rocket tests E3, E9........... 8 56 PMSR.
evaluate the
integration,
accuracy,
performance, and
safe separation
of guided and
unguided 2.75-
inch (7 cm)
rockets fired
from a hovering
or forward
flying
helicopter.
Duration: 1-3
hours.
Explosive...................... Surface Warfare... Subsurface-to- Submarines launch E10.............. 4 28 PMSR.
Surface Missile missiles at
Test. surface maritime
targets with the
goal of
destroying or
disabling enemy
ships or boats.
Duration: 8
hours.
Explosive...................... Surface Warfare... Surface-to-Surface Evaluates the E3, E5........... 10 70 PMSR.
Gunnery Test-- performance and
Large-Caliber. effectiveness of
software and
hardware
modifications or
upgrades of ship-
based large-
caliber gunnery
systems against
surface targets.
3 hours.
Explosive...................... Surface Warfare... Surface-to-Surface Evaluates the E1, E3........... 26 182 PMSR.
Gunnery Test-- performance and
Medium-Caliber. effectiveness of
software and
hardware
modifications or
upgrades of ship-
based medium-
caliber gunnery
systems against
surface targets.
Duration: 3
hours.
Explosive...................... Surface Warfare... Surface-to-Surface Surface ships E9, E10.......... 44 308 PMSR.
Missile Test. launch missiles
at surface
maritime
targets.
Duration: 2-5
hours.
Acoustic....................... Other Testing..... Undersea Range Post installation MFM.............. 30-33 207 BARSTUR.
System Test. node survey and
test and
periodic testing
of range Node
transmit
functionality.
Duration: varies.
Acoustic....................... Other Testing..... Undersea Range Post installation MFM.............. 19-21 127 SOCAL.
System Test. node survey and
test and
periodic testing
of range Node
transmit
functionality.
Duration: varies.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low-frequency, MF = mid-frequency, HF = high-frequency, dB = decibels, L = low, M = medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count. BARSTUR = Barking Sands Tactical Underwater Range, Hawaii = the Hawaii Study Area, PMSR = Point Mugu Sea Range, SCORE =
Southern California Offshore Range, SOAR = Southern California Offshore Anti-Submarine Warfare Range, SOCAL = Southern California Range Complex.

NAVSEA activities are generally aligned with the primary mission
areas used by the fleets and include, but are not limited to, new ship
construction, life cycle support, and other weapon system development
and testing. Testing activities are conducted throughout the life of a
Navy ship, from construction through deactivation from the fleet to
verification of performance and mission capabilities. Activities
include pierside and at-sea testing of ship systems, including sonar,
acoustic countermeasures, radars, torpedoes, weapons, unmanned systems,
and radio

[[Page 32144]]

equipment; tests to determine how the ship performs at sea (sea
trials); development and operational test and evaluation programs for
new technologies and systems, including ship shock trials to test the
survivability of new ships; and testing on all ships and systems that
have undergone overhaul or maintenance. Table 7 summarizes the proposed
testing activities for NAVSEA analyzed within the HCTT Study Area.

Table 7--Proposed NAVSEA Testing Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic....................... Anti-Submarine ASW Mission Ships and their MF1, MFH......... 1 7 Hawaii.
Warfare. Package Testing. supporting
platforms (e.g.,
rotary-wing
aircraft,
unmanned aerial
systems) detect,
localize, and
prosecute
submarines.
Duration: 1-2
weeks with 4-8
hours of active
sonar use per
day.
Acoustic....................... Anti-Submarine ASW Mission Ships and their MF1, MFH......... 1 7 SOCAL.
Warfare. Package Testing. supporting
platforms (e.g.,
rotary-wing
aircraft,
unmanned aerial
systems) detect,
localize, and
prosecute
submarines.
Duration: 1-2
weeks with 4-8
hours of active
sonar use per
day.
Acoustic....................... Anti-Submarine At-Sea Sonar At-sea testing to HFH, HFL, HFM, LF 9-11 70 Hawaii.
Warfare. Testing. ensure systems to HF, LF to MF,
are fully LFH, LFM, MF to
functional in an HF, MF1, MF1K,
open ocean MFH, MFL, MFM.
environment.
Duration: 4
hours to 11 days.
Acoustic....................... Anti-Submarine At-Sea Sonar At-sea testing to HFH, HFL, HFM, LF 16-22 128 SOCAL.
Warfare. Testing. ensure systems to HF, LF to MF,
are fully LFH, LFM, MF to
functional in an HF, MF1, MF1K,
open ocean MFH, MFL, MFM.
environment.
Duration: 4
hours to 11 days.
Acoustic....................... Anti-Submarine At-Sea Sonar At-sea testing to HFH, HFL, HFM, LF 10-20 70 SOAR.
Warfare. Testing. ensure systems to HF, LF to MF,
are fully LFH, LFM, MF to
functional in an HF, MF1, MF1K,
open ocean MFH, MFL, MFM.
environment.
Duration: 4
hours to 11 days.
Acoustic....................... Anti-Submarine At-Sea Sonar At-sea testing to HFH, HFL, HFM, LF 0-1 4 PMRF.
Warfare. Testing. ensure systems to HF, LF to MF,
are fully LFH, LFM, MF to
functional in an HF, MF1, MF1K,
open ocean MFH, MFL, MFM.
environment.
Duration: 4
hours to 11 days.
Acoustic....................... Anti-Submarine Countermeasure Countermeasure HFH, LF to HF, MF 3-6 20 Hawaii, Maui
Warfare. Testing. testing involves to HF, MFH, MFM, Basin, PMRF.
the testing of VHFH.
systems that
detect,
localize, and
engage incoming
weapons,
including marine
vessel targets
and airborne
missiles.
Testing includes
surface ship
torpedo defense
systems, marine
vessel stopping
payloads, and
airborne decoys
against targets.
Duration: 4
hours to 6 days.
Acoustic....................... Anti-Submarine Countermeasure Countermeasure HFH, LF to HF, MF 7-12 25 SOCAL, SCORE.
Warfare. Testing. testing involves to HF, MFH, MFM,
the testing of VHFH.
systems that
detect,
localize, and
engage incoming
weapons,
including marine
vessel targets
and airborne
missiles.
Testing includes
surface ship
torpedo defense
systems, marine
vessel stopping
payloads, and
airborne decoys
against targets.
Duration: 4
hours to 6 days.

[[Page 32145]]

Acoustic....................... Anti-Submarine Pierside Sonar Pierside testing HFH, HFM, MF to 13-25 171 Pearl Harbor.
Warfare. Testing. to ensure HF, MFH, MFM.
systems are
fully functional
in a controlled
pierside
environment
prior to at-sea
test activities
and complete any
troubleshooting.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic....................... Anti-Submarine Pierside Sonar Pierside testing HFH, HFM, MF to 44-55 383 San Diego Bay.
Warfare. Testing. to ensure HF, MFH, MFM.
systems are
fully functional
in a controlled
pierside
environment
prior to at-sea
test activities
and complete any
troubleshooting.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic....................... Anti-Submarine Pierside Sonar Pierside testing HFH, HFM, MF to 15-20 140 Port Hueneme.
Warfare. Testing. to ensure HF, MFH, MFM.
systems are
fully functional
in a controlled
pierside
environment
prior to at-sea
test activities
and complete any
troubleshooting.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic....................... Anti-Submarine Surface Ship Pierside and at- LFL, MF to HF, 3 7 Hawaii.
Warfare. Sonar Testing/ sea testing of MF1, MF1K, MFM.
Maintenance. ship systems
occur
periodically
following major
maintenance
periods and for
routine
maintenance.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic....................... Anti-Submarine Surface Ship Pierside and at- LFL, MF to HF, 3 21 Pearl Harbor.
Warfare. Sonar Testing/ sea testing of MF1, MF1K, MFM.
Maintenance. ship systems
occur
periodically
following major
maintenance
periods and for
routine
maintenance.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic....................... Anti-Submarine Surface Ship Pierside and at- LFL, MF to HF, 3 21 SOCAL.
Warfare. Sonar Testing/ sea testing of MF1, MF1K, MFM.
Maintenance. ship systems
occur
periodically
following major
maintenance
periods and for
routine
maintenance.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic....................... Anti-Submarine Surface Ship Pierside and at- LFL, MF to HF, 3 21 San Diego Bay.
Warfare. Sonar Testing/ sea testing of MF1, MF1K, MFM.
Maintenance. ship systems
occur
periodically
following major
maintenance
periods and for
routine
maintenance.
Duration: up to
3 weeks, with
intermittent
sonar use.
Acoustic and Explosive......... Anti-Submarine Torpedo Air, surface, or E8, E11, HFH, MF 1-5 17 Hawaii, SOCAL,
Warfare. (Explosive) submarine crews to HF, MF1, MFH, PMSR.
Testing. employ explosive MFM.
and non-
explosive
torpedoes
against
artificial
targets.
Duration: 1-2
days, 8-12 hours
per day.
Acoustic....................... Anti-Submarine Torpedo (Non- Air, surface, or HFH, HFM, LF to 13-17 96 Hawaii, SOCAL,
Warfare. Explosive) submarine crews HF, MF to HF, BARSTUR, PMSR.
Testing. employ non- MF1, MFH, MFL,
explosive MFM, VHFH.
torpedoes
against
submarines,
surface vessels,
or artificial
targets.
Duration: up to
2 weeks.
Explosive...................... Mine Warfare..... Mine Air, surface, and E4............... 18-45 315 SOCAL.
Countermeasure subsurface
and vessels
Neutralization neutralize
Testing. threat mines and
mine-like
objects.
Duration: 1-10
days, with
intermittent use
of
countermeasure
systems.
Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 0-1 7 PMRF.
Countermeasure associated
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.
Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 16 109 Maui Basin.
Countermeasure associated
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.
Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 6 36 CPAAA.
Countermeasure associated
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.

[[Page 32146]]

Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 6 36 SSTC.
Countermeasure associated
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.
Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 6 37 Tanner Bank.
Countermeasure associated
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.
Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 6 42 Imperial Beach
Countermeasure associated Minefield.
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.
Acoustic and Explosive......... Mine Warfare..... Mine Vessels and E4, HFM, MFH..... 1 7 PMSR.
Countermeasure associated
Mission Package aircraft conduct
Testing. mine
countermeasure
operations.
Duration: 1-2
weeks, with
intermittent use
of
countermeasure
systems.
Acoustic....................... Mine Warfare..... Mine Detection Air, surface, and HFH.............. 4-8 28 Hawaii.
and subsurface
Classification vessels and
Testing. systems detect,
classify, and
avoid mines and
mine-like
objects. Vessels
also assess
their potential
susceptibility
to mines and
mine-like
objects.
Duration: up to
24 days, 8-12
hours per day.
Acoustic....................... Mine Warfare..... Mine Detection Air, surface, and HFH.............. 0-1 4 Imperial Beach
and subsurface Minefield.
Classification vessels and
Testing. systems detect,
classify, and
avoid mines and
mine-like
objects. Vessels
also assess
their potential
susceptibility
to mines and
mine-like
objects.
Duration: up to
24 days, 8-12
hours per day.
Acoustic....................... Mine Warfare..... Mine Detection Air, surface, and HFH.............. 2 14 Maui Basin.
and subsurface
Classification vessels and
Testing. systems detect,
classify, and
avoid mines and
mine-like
objects. Vessels
also assess
their potential
susceptibility
to mines and
mine-like
objects.
Duration: up to
24 days, 8-12
hours per day.
Acoustic....................... Mine Warfare..... Mine Detection Air, surface, and HFH.............. 2 14 Tanner Bank.
and subsurface
Classification vessels and
Testing. systems detect,
classify, and
avoid mines and
mine-like
objects. Vessels
also assess
their potential
susceptibility
to mines and
mine-like
objects.
Duration: up to
24 days, 8-12
hours per day.
Acoustic....................... Mine Warfare..... Mine Detection Air, surface, and HFH.............. 4-8 28 PMSR.
and subsurface
Classification vessels and
Testing. systems detect,
classify, and
avoid mines and
mine-like
objects. Vessels
also assess
their potential
susceptibility
to mines and
mine-like
objects.
Duration: up to
24 days, 8-12
hours per day.
Acoustic....................... Mine Warfare..... Mine Detection Air, surface, and HFH.............. 4-9 30 SOCAL.
and subsurface
Classification vessels and
Testing. systems detect,
classify, and
avoid mines and
mine-like
objects. Vessels
also assess
their potential
susceptibility
to mines and
mine-like
objects.
Duration: up to
24 days, 8-12
hours per day.
Acoustic....................... Unmanned Systems. Unmanned Testing involves HFL, HFM, MF to 2 14 Pearl Harbor.
Underwater the production HF, MFM, VHFH,
Vehicle Testing. or upgrade of VHFL.
unmanned
underwater
vehicles. This
may include
testing mine
detection
capabilities,
evaluating the
basic functions
of individual
platforms, or
conducting
complex events
with multiple
vehicles.
Duration: up to
35 days, gliders
could operate
for multiple
months.

[[Page 32147]]

Acoustic....................... Unmanned Systems. Unmanned Testing involves HFL, HFM, MF to 230 1,610 Port Hueneme.
Underwater the production HF, MFM, VHFH,
Vehicle Testing. or upgrade of VHFL.
unmanned
underwater
vehicles. This
may include
testing mine
detection
capabilities,
evaluating the
basic functions
of individual
platforms, or
conducting
complex events
with multiple
vehicles.
Duration: up to
35 days, gliders
could operate
for multiple
months.
Acoustic....................... Unmanned Systems. Unmanned Testing involves HFL, HFM, MF to 10-15 85 SOCAL.
Underwater the production HF, MFM, VHFH,
Vehicle Testing. or upgrade of VHFL.
unmanned
underwater
vehicles. This
may include
testing mine
detection
capabilities,
evaluating the
basic functions
of individual
platforms, or
conducting
complex events
with multiple
vehicles.
Duration: up to
35 days, gliders
could operate
for multiple
months.
Acoustic....................... Unmanned Systems. Unmanned Testing involves HFL, HFM, MF to 440 3,080 SOCAL nearshore.
Underwater the production HF, MFM, VHFH,
Vehicle Testing. or upgrade of VHFL.
unmanned
underwater
vehicles. This
may include
testing mine
detection
capabilities,
evaluating the
basic functions
of individual
platforms, or
conducting
complex events
with multiple
vehicles.
Duration: up to
35 days, gliders
could operate
for multiple
months.
Acoustic....................... Vessel Evaluation In-Port Each combat MF1.............. 5 30 Pearl Harbor.
Maintenance system is tested
Testing. to ensure they
are functioning
in a technically
acceptable
manner and are
operationally
ready to support
at-sea testing.
Duration: 3
weeks.
Acoustic....................... Vessel Evaluation In-Port Each combat MF1.............. 5 30 San Diego Bay.
Maintenance system is tested
Testing. to ensure they
are functioning
in a technically
acceptable
manner and are
operationally
ready to support
at-sea testing.
Duration: 3
weeks.
Acoustic....................... Vessel Evaluation In-Port Each combat MF1.............. 10 70 Port Hueneme.
Maintenance system is tested
Testing. to ensure they
are functioning
in a technically
acceptable
manner and are
operationally
ready to support
at-sea testing.
Duration: 3
weeks.
Acoustic....................... Vessel Evaluation Signature Surface ship and HFM, MFM......... 2-4 14 Hawaii.
Analysis submarine
Operations. testing of
electromagnetic,
acoustic,
optical, and
radar signature
measurements.
Duration: 1-5
days.
Acoustic....................... Vessel Evaluation Signature Surface ship and HFM, MFM......... 0-1 1 San Diego Bay.
Analysis submarine
Operations. testing of
electromagnetic,
acoustic,
optical, and
radar signature
measurements.
Duration: 1-5
days.
Explosive...................... Vessel Evaluation Small Ship Shock Underwater E16.............. 0-1 1 SOCAL.
Trial. detonations are
used to test new
ships or major
upgrades.
Duration: up to
3 weeks.
Acoustic....................... Vessel Evaluation Submarine Sea Submarine weapons HFH, HFM, LF to 2-4 12 Hawaii.
Trials--Weapons and sonar HF, MFH, MFL.
System Testing. systems are
tested at-sea to
meet integrated
combat system
certification
requirements.
Duration: up to
7 days.
Acoustic....................... Vessel Evaluation Submarine Sea Submarine weapons HFH, HFM, LF to 2-4 12 SOCAL.
Trials--Weapons and sonar HF, MFH, MFL.
System Testing. systems are
tested at-sea to
meet integrated
combat system
certification
requirements.
Duration: up to
7 days.

[[Page 32148]]

Acoustic and Explosive......... Vessel Evaluation Surface Warfare Tests capability E3, E5, E6, E7, 0-12 48 Hawaii.
Testing. of shipboard E8, E9, HFH, MFM.
sensors to
detect, track,
and engage
surface targets.
Testing may
include ships
defending
against surface
targets using
explosive and
non-explosive
rounds, gun
system
structural test
firing, and
demonstration of
the response to
Call for Fire
against land-
based targets
(simulated by
sea-based
locations).
Duration: 7 days.
Acoustic and Explosive......... Vessel Evaluation Surface Warfare Tests capability E3, E5, E6, E7, 4 35 PMRF.
Testing. of shipboard E8, E9, HFH, MFM.
sensors to
detect, track,
and engage
surface targets.
Testing may
include ships
defending
against surface
targets using
explosive and
non-explosive
rounds, gun
system
structural test
firing, and
demonstration of
the response to
Call for Fire
against land-
based targets
(simulated by
sea-based
locations).
Duration: 7 days.
Acoustic and Explosive......... Vessel Evaluation Surface Warfare Tests capability E3, E5, E6, E7, 3-15 39 SOCAL.
Testing. of shipboard E8, E9, HFH, MFM.
sensors to
detect, track,
and engage
surface targets.
Testing may
include ships
defending
against surface
targets using
explosive and
non-explosive
rounds, gun
system
structural test
firing, and
demonstration of
the response to
Call for Fire
against land-
based targets
(simulated by
sea-based
locations).
Duration: 7 days.
Acoustic and Explosive......... Vessel Evaluation Surface Warfare Tests capability E3, E5, E6, E7, 3-6 30 SOAR.
Testing. of shipboard E8, E9, HFH, MFM.
sensors to
detect, track,
and engage
surface targets.
Testing may
include ships
defending
against surface
targets using
explosive and
non-explosive
rounds, gun
system
structural test
firing, and
demonstration of
the response to
Call for Fire
against land-
based targets
(simulated by
sea-based
locations).
Duration: 7 days.
Acoustic and Explosive......... Vessel Evaluation Surface Warfare Tests capability E3, E5, E6, E7, 4-12 36 SCORE.
Testing. of shipboard E8, E9, HFH, MFM.
sensors to
detect, track,
and engage
surface targets.
Testing may
include ships
defending
against surface
targets using
explosive and
non-explosive
rounds, gun
system
structural test
firing, and
demonstration of
the response to
Call for Fire
against land-
based targets
(simulated by
sea-based
locations).
Duration: 7 days.
Acoustic and Explosive......... Vessel Evaluation Surface Warfare Tests capability E3, E5, E6, E7, 7-20 67 PMSR.
Testing. of shipboard E8, E9, HFH, MFM.
sensors to
detect, track,
and engage
surface targets.
Testing may
include ships
defending
against surface
targets using
explosive and
non-explosive
rounds, gun
system
structural test
firing, and
demonstration of
the response to
Call for Fire
against land-
based targets
(simulated by
sea-based
locations).
Duration: 7 days.

[[Page 32149]]

Acoustic....................... Vessel Evaluation Undersea Warfare Ships demonstrate HFH, MF1, MFH, 1-7 26 Hawaii.
Testing. capability of MFM.
countermeasure
systems and
underwater
surveillance,
weapons
engagement, and
communications
systems. This
tests ships'
ability to
detect, track,
and engage
undersea
targets.
Duration: up to
10 days.
Acoustic....................... Vessel Evaluation Undersea Warfare Ships demonstrate HFH, MF1, MFH, 2-3 16 PMRF.
Testing. capability of MFM.
countermeasure
systems and
underwater
surveillance,
weapons
engagement, and
communications
systems. This
tests ships'
ability to
detect, track,
and engage
undersea
targets.
Duration: up to
10 days.
Acoustic....................... Vessel Evaluation Undersea Warfare Ships demonstrate HFH, MF1, MFH, 23-43 154 SOCAL.
Testing. capability of MFM.
countermeasure
systems and
underwater
surveillance,
weapons
engagement, and
communications
systems. This
tests ships'
ability to
detect, track,
and engage
undersea
targets.
Duration: up to
10 days.
Acoustic....................... Vessel Evaluation Undersea Warfare Ships demonstrate HFH, MF1, MFH, 2-14 56 SCORE.
Testing. capability of MFM.
countermeasure
systems and
underwater
surveillance,
weapons
engagement, and
communications
systems. This
tests ships'
ability to
detect, track,
and engage
undersea
targets.
Duration: up to
10 days.
Acoustic and Explosive......... Other Testing.... Acoustic and Research using E7, LFM.......... 1 7 Hawaii.
Oceanographic active
Research. transmissions
from sources
deployed from
ships, aircraft,
and unmanned
underwater
vehicles.
Research sources
can be used as
proxies for
current and
future Navy
systems.
Duration: up to
14 days.
Acoustic and Explosive......... Other Testing.... Acoustic and Research using E7, LFM.......... 4-5 31 PMRF.
Oceanographic active
Research. transmissions
from sources
deployed from
ships, aircraft,
and unmanned
underwater
vehicles.
Research sources
can be used as
proxies for
current and
future Navy
systems.
Duration: up to
14 days.
Acoustic and Explosive......... Other Testing.... Acoustic and Research using E7, LFM.......... 2 14 SOCAL.
Oceanographic active
Research. transmissions
from sources
deployed from
ships, aircraft,
and unmanned
underwater
vehicles.
Research sources
can be used as
proxies for
current and
future Navy
systems.
Duration: up to
14 days.
Acoustic and Explosive......... Other Testing.... Acoustic and Research using E7, LFM.......... 0-1 3 PMSR.
Oceanographic active
Research. transmissions
from sources
deployed from
ships, aircraft,
and unmanned
underwater
vehicles.
Research sources
can be used as
proxies for
current and
future Navy
systems.
Duration: up to
14 days.
Acoustic....................... Other Testing.... Insertion/ Testing of HFM, LF to MF, 2 14 Hawaii.
Extraction. submersibles LFH.
capable of
inserting and
extracting
personnel and
payloads into
denied areas
from strategic
distances.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Insertion/ Testing of HFM, LF to MF, 2 14 SOCAL.
Extraction. submersibles LFH.
capable of
inserting and
extracting
personnel and
payloads into
denied areas
from strategic
distances.
Duration: up to
30 days.
Acoustic and Explosive......... Other Testing.... Semi-Stationary Semi-stationary E4, HFH.......... 4-8 40 Pearl Harbor.
Equipment equipment (e.g.,
Testing. hydrophones) is
deployed to
determine
functionality.
Duration: up to
14 days.

[[Page 32150]]

Acoustic and Explosive......... Other Testing.... Semi-Stationary Semi-stationary E4, HFH.......... 4-8 40 San Diego Bay.
Equipment equipment (e.g.,
Testing. hydrophones) is
deployed to
determine
functionality.
Duration: up to
14 days.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low-frequency, MF = mid-frequency, HF = high-frequency, dB = decibels, L = low, M = medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count. BARSTUR = Barking Sands Tactical Underwater Range, CPAAA = Camp Pendleton Amphibious Assault Area, Hawaii = the Hawaii
Study Area, PMRF = Pacific Missile Range Facility, PMSR = Point Mugu Sea Range, SCORE = Southern California Offshore Range, SOAR = Southern California
Offshore Anti-Submarine Range, SOCAL = Southern California Range Complex, SSTC = Silver Strand Training Complex.

NAVWAR is the information warfare systems command for the Navy. The
mission of NAVWAR is to identify, develop, deliver, and sustain
information warfare capabilities and services that enable naval, joint,
coalition, and other national missions operating in warfighting domains
from seabed to space; and to perform such other functions and tasks as
directed. NAVWAR Systems Center Pacific is the research and development
part of NAVWAR focused on developing and transitioning technologies in
the area of command, control, communications, computers, intelligence,
surveillance, and reconnaissance. Table 8 summarizes the proposed
testing activities for NAVWAR analyzed within the HCTT Study Area.

Table 8--Proposed NAVWAR Testing Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic....................... Acoustic and Acoustic, Testing includes HFM, LF to HF, 2 14 Pearl Harbor.
Oceanographic Oceanographic, activities LFM, MF to HF,
Science and and Energy utilizing the MFH, MFM.
Technology. Research. marine
environment for
research, and
test and
evaluation.
Tests may
involve radar,
environmental
sensors,
magnetic
sensors, passive
and active
acoustic
sensors, optical
sensors, and
lasers. Surface
operations
utilize a
variety of
vessels and
vehicles for
deployment,
operation, and
testing. Energy
research and
harvesting would
include the
development and
testing of
energy
harvesting and
storage
technologies,
maritime
charging
stations, remote
communications,
and associated
infrastructure.
This testing
would also
include
bioacoustics
research in
support of
marine mammal
science.
Duration: up to
14 days.
Acoustic....................... Acoustic and Acoustic, Testing includes HFM, LF to HF, 10-16 88 SOCAL.
Oceanographic Oceanographic, activities LFM, MF to HF,
Science and and Energy utilizing the MFH, MFM.
Technology. Research. marine
environment for
research, and
test and
evaluation.
Tests may
involve radar,
environmental
sensors,
magnetic
sensors, passive
and active
acoustic
sensors, optical
sensors, and
lasers. Surface
operations
utilize a
variety of
vessels and
vehicles for
deployment,
operation, and
testing. Energy
research and
harvesting would
include the
development and
testing of
energy
harvesting and
storage
technologies,
maritime
charging
stations, remote
communications,
and associated
infrastructure.
This testing
would also
include
bioacoustics
research in
support of
marine mammal
science.
Duration: up to
14 days.

[[Page 32151]]

Acoustic....................... Acoustic and Acoustic, Testing includes HFM, LF to HF, 133-160 1,012 San Diego Bay.
Oceanographic Oceanographic, activities LFM, MF to HF,
Science and and Energy utilizing the MFH, MFM.
Technology. Research. marine
environment for
research, and
test and
evaluation.
Tests may
involve radar,
environmental
sensors,
magnetic
sensors, passive
and active
acoustic
sensors, optical
sensors, and
lasers. Surface
operations
utilize a
variety of
vessels and
vehicles for
deployment,
operation, and
testing. Energy
research and
harvesting would
include the
development and
testing of
energy
harvesting and
storage
technologies,
maritime
charging
stations, remote
communications,
and associated
infrastructure.
This testing
would also
include
bioacoustics
research in
support of
marine mammal
science.
Duration: up to
14 days.
Acoustic....................... Acoustic and Acoustic, Testing includes HFM, LF to HF, 2-4 20 PMSR.
Oceanographic Oceanographic, activities LFM, MF to HF,
Science and and Energy utilizing the MFH, MFM.
Technology. Research. marine
environment for
research, and
test and
evaluation.
Tests may
involve radar,
environmental
sensors,
magnetic
sensors, passive
and active
acoustic
sensors, optical
sensors, and
lasers. Surface
operations
utilize a
variety of
vessels and
vehicles for
deployment,
operation, and
testing. Energy
research and
harvesting would
include the
development and
testing of
energy
harvesting and
storage
technologies,
maritime
charging
stations, remote
communications,
and associated
infrastructure.
This testing
would also
include
bioacoustics
research in
support of
marine mammal
science.
Duration: up to
14 days.
Acoustic....................... Other Testing.... Communications... Testing of LF to MF......... 1 7 Hawaii.
maritime
communications,
underwater
network systems
with fiber
optics cables,
laser
communications,
acoustic modem
networks and
launching of
communication
payloads and
objects.
Durations:
typically 5 days
for 6-8 hours
per day.
Acoustic....................... Other Testing.... Communications... Testing of LF to MF......... 4 28 SOCAL.
maritime
communications,
underwater
network systems
with fiber
optics cables,
laser
communications,
acoustic modem
networks and
launching of
communication
payloads and
objects.
Durations:
typically 5 days
for 6-8 hours
per day.
Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 15-17 108 Hawaii.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.

[[Page 32152]]

Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 2 14 Pearl Harbor.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 83-123 700 SOCAL.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 5-10 50 CPAAA.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 8-10 62 San Diego Bay.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.

[[Page 32153]]

Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 11-19 101 SCIUR.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 38-51 305 SCORE.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Intelligence, Testing Air gun, HFL, 44-62 362 SSTC.
Surveillance, deployable HFM, LF, LF to
Reconnaissance. autonomous HF, LFH, MF to
undersea HF, MFH, MFL,
technologies MFM, VHFH.
that may include
mine detection
and
classification,
detection and
classification
of targets of
interest,
sensors on the
undersea systems
testbed,
expansion of the
undersea systems
testbed with
fiber optic
cables and
nodes, sensor
systems to
detect mine
shapes on ship
hulls and pier
structures,
sensors for
swimmer
interdiction and
other threats,
and sensor
systems that can
detect
explosive,
radioactive, and
other signatures
of concern.
Duration: up to
30 days.
Acoustic....................... Other Testing.... Vehicle Testing.. Testing of HFL, HFM, LFH, 15-22 123 Hawaii.
surface, MFH, MFL, VHFH.
subsurface and
airborne
vehicles, sensor
systems,
payloads,
communications,
and navigation
which may
involve remotely
operated
vehicles,
autonomous
underwater
vehicles,
autonomous
surface
vehicles, and
autonomous
aerial vehicles.
Testing may
involve
evaluating
individual
vehicles and
payloads or
conducting
complex events
with multiple
vehicles.
Durations:
typically 5 days
for 6-8 hours
per day.
Acoustic....................... Other Testing.... Vehicle Testing.. Testing of HFL, HFM, LFH, 32-39 245 SOCAL.
surface, MFH, MFL, VHFH.
subsurface and
airborne
vehicles, sensor
systems,
payloads,
communications,
and navigation
which may
involve remotely
operated
vehicles,
autonomous
underwater
vehicles,
autonomous
surface
vehicles, and
autonomous
aerial vehicles.
Testing may
involve
evaluating
individual
vehicles and
payloads or
conducting
complex events
with multiple
vehicles.
Durations:
typically 5 days
for 6-8 hours
per day.

[[Page 32154]]

Acoustic....................... Other Testing.... Vehicle Testing.. Testing of HFL, HFM, LFH, 10-12 76 SCORE.
surface, MFH, MFL, VHFH.
subsurface and
airborne
vehicles, sensor
systems,
payloads,
communications,
and navigation
which may
involve remotely
operated
vehicles,
autonomous
underwater
vehicles,
autonomous
surface
vehicles, and
autonomous
aerial vehicles.
Testing may
involve
evaluating
individual
vehicles and
payloads or
conducting
complex events
with multiple
vehicles.
Durations:
typically 5 days
for 6-8 hours
per day.
Acoustic....................... Other Testing.... Vehicle Testing.. Testing of HFL, HFM, LFH, 4-8 40 Transit Corridor.
surface, MFH, MFL, VHFH.
subsurface and
airborne
vehicles, sensor
systems,
payloads,
communications,
and navigation
which may
involve remotely
operated
vehicles,
autonomous
underwater
vehicles,
autonomous
surface
vehicles, and
autonomous
aerial vehicles.
Testing may
involve
evaluating
individual
vehicles and
payloads or
conducting
complex events
with multiple
vehicles.
Durations:
typically 5 days
for 6-8 hours
per day.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low-frequency, MF = mid-frequency, HF = high-frequency, dB = decibels, L = low, M = medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count. CPAAA = Camp Pendleton Amphibious Assault Area, Hawaii = the Hawaii Study Area, PMRF = Pacific Missile Range Facility,
PMSR = Point Mugu Sea Range, SCIUR = San Clemente Island Underwater Range, SCORE = Southern California Offshore Range, SOCAL = Southern California
Range Complex, SSTC = Silver Strand Training Complex.

ONR's mission is to plan, foster, and encourage scientific research
in recognition of its paramount importance as related to the
maintenance of future naval power, and the preservation of national
security. ONR manages the Navy's basic, applied, and advanced research
to foster transition from science and technology to higher levels of
research, development, test, and evaluation. ONR is also a parent
organization for the Naval Research Laboratory, which operates as the
Navy's corporate research laboratory and conducts a broad
multidisciplinary program of scientific research and advanced
technological development. Table 9 summarizes the proposed testing
activities for the ONR analyzed within the HCTT Study Area.

Table 9--Proposed ONR Testing Activities Analyzed Within the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Number of
Stressor category Activity type Activity name Description Source bin activities activities Location
1-year 7-year
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic.......... Acoustic and Acoustic and Research using E1, E3, Air gun and 4-5 32 Hawaii.
Oceanographic Oceanographic active non-explosive
Science and Research. transmissions from impulses, HFH,
Technology. sources deployed HFM, LFH, LFM,
from ships, MFH, MFM, VHFM.
aircraft, and
unmanned underwater
vehicles. Research
sources can be used
as proxies for
current and future
Navy systems.
Duration: up to 14
days.
Acoustic.......... Acoustic and Acoustic and Research using E1, E3, Air gun and 4-5 32 SOCAL.
Oceanographic Oceanographic active non-explosive
Science and Research. transmissions from impulses, HFH,
Technology. sources deployed HFM, LFH, LFM,
from ships, MFH, MFM, VHFM.
aircraft, and
unmanned underwater
vehicles. Research
sources can be used
as proxies for
current and future
Navy systems.
Duration: up to 14
days.
Acoustic.......... Acoustic and Acoustic and Research using E1, E3, Air gun and 1-2 10 Acoustic Research
Oceanographic Oceanographic active non-explosive Area.
Science and Research. transmissions from impulses, HFH,
Technology. sources deployed HFM, LFH, LFM,
from ships, MFH, MFM, VHFM.
aircraft, and
unmanned underwater
vehicles. Research
sources can be used
as proxies for
current and future
Navy systems.
Duration: up to 14
days.

[[Page 32155]]

Acoustic.......... Acoustic and Acoustic and Research using E1, E3, Air gun and 1-2 9 PMSR.
Oceanographic Oceanographic active non-explosive
Science and Research. transmissions from impulses, HFH,
Technology. sources deployed HFM, LFH, LFM,
from ships, MFH, MFM, VHFM.
aircraft, and
unmanned underwater
vehicles. Research
sources can be used
as proxies for
current and future
Navy systems.
Duration: up to 14
days.
Acoustic.......... Acoustic and Acoustic and Research using E1, E3, Air gun and 1-2 14 NOCAL.
Oceanographic Oceanographic active non-explosive
Science and Research. transmissions from impulses, HFH,
Technology. sources deployed HFM, LFH, LFM,
from ships, MFH, MFM, VHFM.
aircraft, and
unmanned underwater
vehicles. Research
sources can be used
as proxies for
current and future
Navy systems.
Duration: up to 14
days.
Acoustic.......... Acoustic and Long Range Acoustic Low-frequency bottom- LFM................ 1-2 11 Hawaii.
Oceanographic Communications. mounted acoustic
Science and source off of the
Technology. Hawaiian Island of
Kaua'i would
transmit a variety
of acoustic
communications
sequences.
Duration: year-
round; active
transmissions 200
days a year.
Acoustic.......... Acoustic and Mine Countermeasure Test involves the MFH................ 1-2 11 Hawaii.
Oceanographic Technology Research. use of broadband
Science and acoustic sources on
Technology. unmanned underwater
vehicles. Duration:
up to 30 days.
Acoustic.......... Acoustic and Mine Countermeasure Test involves the MFH................ 6-8 50 SOCAL.
Oceanographic Technology Research. use of broadband
Science and acoustic sources on
Technology. unmanned underwater
vehicles. Duration:
up to 30 days.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low-frequency, MF = mid-frequency, HF = high-frequency, dB = decibels, L = low, M = medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count. Hawaii = the Hawaii Study Area, NOCAL = Northern California Range Complex, PMSR = Point Mugu Sea Range, SOCAL = Southern
California Range Complex.

Vessel Movement
Vessels used as part of the proposed activities include both
surface and sub-surface operations of both manned and unmanned vessels
(USVs, UUVs). Vessels used as part of the Action Proponents' activities
include ships, submarines, unmanned vessels, and boats ranging in size
from small, 22 ft (6.7 m) rigid hull inflatable boats to aircraft
carriers with lengths up to 1,092 ft (332.8 m). Unmanned systems may
include vehicles ranging from 4-16 ft (1.2-4.9 m) but typical size of
USVs is 36-328 ft (11-100 m) while UUVs are 33-98 ft (10-30 m) in
length. The Marine Corps operates small boats from 10-50 ft (3-15.2 m)
in length and include small unit riverine craft, rigid hull inflatable
boats and amphibious combat vehicles. Coast Guard vessels range in size
from small boats between 13 and 65 ft (3.9 to 19.8 m) to large cutters
with lengths up to 418 ft (127.4 m).
Large Navy ships greater than 350 ft (107 m) generally operate at
speeds in the range of 10 to 15 knots (kn; 18.5 to 27.8 kilometers per
hour (km/hr)) for fuel conservation. Submarines generally operate at
lower speeds in transit and even lower speeds for certain tactical
maneuvers. Small craft (considered in this proposed rule to be less
than 60 ft (18 m) in length) have much more variable speeds (dependent
on the mission). While these speeds for large Navy vessels are
representative of most events, some of the Action Proponents' vessels
may need to temporarily operate outside of these parameters. For
example, to produce the required relative wind speed over the flight
deck, an aircraft carrier vessel group engaged in flight operations
must adjust its speed through the water accordingly. Additionally,
there are specific events including high speed tests of newly
constructed vessels. The Navy also anticipates testing large USVs, some
of which would be at high speed. Conversely, there are other instances
such as launch and recovery of a small rigid hull inflatable boat,
vessel boarding, search and seizure training events, or retrieval of a
target when vessels would be stopped or moving slowly ahead to maintain
steerage. The Coast Guard currently operates approximately 250 cutters.
Larger cutters (over 181 ft (55 m) in length) are controlled by Area
Commands. The Pacific Area command is located in Alameda, CA. Smaller
cutters come under control of district commands. There are four
districts in the Pacific Area. Cutters usually carry a motor surf boat
and/or a rigid-hulled inflatable boat.
The Coast Guard operates approximately 1,600 boats, defined as any
vessel less than 65 ft (20 m) in length. These boats generally operate
near shore and on inland waterways. The most common is 25 ft (7.6 m)
long, of which the Coast Guard has more than 350; the shortest is 13 ft
(4.0 m). Boat training includes small boat crews engaging surface
targets with small- and medium-caliber weapons.
The number of vessels used in the HCTT Study Area varies based on
military readiness requirements, deployment schedules, annual budgets,
and other unpredictable factors. Most military readiness activities
involve the use of vessels. These activities could be widely dispersed
throughout the HCTT Study Area, but would typically be conducted near
naval ports, piers, and range areas. Activities involving vessel
movements occur intermittently and are variable in duration, ranging
from a few hours to multiple weeks.
Action Proponent vessel traffic would especially be concentrated
near San Diego, California and Pearl Harbor, Hawaii. There is no
seasonal differentiation in vessel use. Large vessel movement primarily
occurs with the majority of the traffic flowing

[[Page 32156]]

between the installations and the OPAREAS. Support craft would be more
concentrated in the coastal waters in the areas of naval installations,
ports, and ranges.
The number of testing activities that include the use of vessels is
around 18 percent lower than the number of training activities, but
testing activities are more likely to include the use of larger
unmanned vessels (although these are expected to transition to training
use during the effective period of the rule, if finalized). In
addition, testing often occurs jointly with a training event so it is
likely that the testing activity would be conducted from a vessel that
was also conducting a training activity. Vessel movement in conjunction
with testing activities could occur throughout the Study Area, but
would typically be conducted near naval ports, piers, and range
complexes.
Additionally, a variety of smaller craft would be operated within
the HCTT Study Area. Small craft types, sizes, and speeds vary. During
military readiness activities, speeds generally range from 10 to 14 kn
(18.5 to 25.9 km/hr); however, vessels can and will, on occasion,
operate within the entire spectrum of their specific operational
capabilities. During modernization and sustainment of ranges
activities, vessels would operate more slowly, typically 3 kn (5.6 km/
hr) or less. In all cases, the vessels/craft will be operated in a safe
manner consistent with the local conditions.
Foreign Navies
In furtherance of national security objectives, foreign militaries
may participate in multinational training and testing events in the
Study Area. Foreign military activities that are planned by and under
the substantial control and responsibility of the Action Proponents are
included in the proposed action. These participants could be in various
training or testing events described in appendix A of the 2024 HCTT
Draft EIS/OEIS, and their effects are analyzed in this proposed rule.
However, when foreign military vessels operate independently within the
Study Area as sovereign vessels outside the planning, control, and
responsibility of the Action Proponents, those activities are not
considered part of the specified activity. There are many reasons why
foreign military vessels may traverse U.S. waters or come into U.S.
port, not all of which are at the behest of any of the Action
Proponents. Foreign military vessels and aircraft operate pursuant to
their own national authorities and have independent rights under
customary international law, embodied in the principle of sovereign
immunity, to engage in various activities on the world's oceans and
seas. When foreign militaries are participating in a U.S. Navy planned
and substantially controlled exercise or event, foreign military use of
sonar and explosives, when combined with the U.S. Navy's use of sonar
and explosives, would not result in exceedance of the analyzed levels
(within each Navy Acoustic Effects Model (NAEMO) modeled sonar and
explosive bin) used for estimating predicted impacts, which formed the
basis of our acoustic impacts effects analysis that was used to
estimate take in this proposed rule.
The most significant joint training event is the Rim of the Pacific
(RIMPAC), a multi-national training exercise held every-other-year
primarily in the HRC. The participation level of foreign military
vessels in U.S. Navy-led training or testing events within the HRC and
within SOCAL differs greatly between RIMPAC and non-RIMPAC years. For
example, in 2019 (a non-RIMPAC year), there were 0.1 foreign navy
surface vessel at-sea days (i.e., 1 day = 24 hours) within HRC and 20
foreign navy at-sea days within SOCAL (Navy 2021). Out of 56 U.S.-led
training events in 2019, 4 involved foreign navy vessels, with an
average time per event of 8.7 hours. During RIMPAC 2022, foreign
vessels operated and/or transited through the HRC for 576 hours (24
days). In 2023 (another non-RIMPAC year), there was no foreign vessel
participation within SOCAL. Even in a RIMPAC year, the days at sea for
foreign militaries engaged in a Navy-led training or testing activity
accounts for a small, but variable, percentage compared to the U.S.
Navy activities. For instance, the 2020 foreign military participation
(a RIMPAC-year) was 1.5 percent of the U.S. Navy's average days at sea
(32 days out of an estimated 2,056 days at sea). During RIMPAC 2024,
twenty-five foreign surface vessels participated for a combined 5,000
hours in U.S.-led training events. Therefore, foreign surface vessel
activity is estimated to conservatively account for up to 10 percent of
the U.S. Navy's annual at sea time in HCTT (205 days out of an
estimated 2,056 days at sea).
Please see the Proposed Mitigation Measures section and Proposed
Reporting section of this proposed rule for information about
mitigation and reporting related to foreign navy activities in the HCTT
Study Area.
When foreign militaries are participating in a U.S. Navy-led
exercise or event, foreign military use of sonar and explosives, when
combined with the U.S. Navy's use of sonar and explosives, would not
result in exceedance of the analyzed levels (within each NAEMO modeled
sonar and explosive bin) used for estimating predicted impacts, which
formed the basis of our acoustic impacts effects analysis that was used
to estimate take in this proposed rule. Please see the Proposed
Mitigation Measures section and Proposed Reporting section of this
proposed rule for information about mitigation and reporting related to
foreign navy activities in the HCTT Study Area.
Standard Operating Procedures
For training and testing to be effective, Action Proponent
personnel must be able to safely use their sensors, platforms, weapons,
and other devices to their optimum capabilities and as intended for use
in missions and combat operations. The Action Proponents have developed
standard operating procedures through decades of experience to provide
for safety and mission success. Because they are essential to safety
and mission success, standard operating procedures are part of the
Proposed Action and are considered in the environmental analysis for
applicable resources (see chapter 3 (Affected Environment and
Environmental Consequences) of the 2024 HCTT Draft EIS/OEIS). While
standard operating procedures are designed for the safety of personnel
and equipment and to ensure the success of training and testing
activities, their implementation often yields additional benefits on
environmental, socioeconomic, public health and safety, and cultural
resources.
Because standard operating procedures are essential to safety and
mission success, the Action Proponents consider them to be part of the
proposed activities and have included them in the environmental
analysis. Standard operating procedures that are recognized as
providing a potential secondary benefit on marine mammals during
training and testing activities are noted below.
Vessel safety;
Weapons firing safety;
Target deployment safety;
Towed in-water device safety;
Pile driving safety; and
Coastal zones.
Standard operating procedures (which are implemented regardless of
their secondary benefits) are different from mitigation measures (which
are designed entirely for the purpose of avoiding or reducing impacts).
Information on mitigation measures is provided in the Proposed
Mitigation Measures section.

[[Page 32157]]

Description of Stressors

The Action Proponents use a variety of sensors, platforms, weapons,
and other devices. Military readiness activities using these systems
may introduce sound and energy into the environment. The proposed
military readiness activities were evaluated to identify specific
components that would act as stressors by having direct or indirect
impacts on marine mammals and their habitat. This analysis included
identification of the spatial variation of the identified stressors.
The following subsections describe the acoustic and explosive stressors
for marine mammals and their habitat within the HCTT Study Area. Each
description contains a list of activities that may generate the
stressor. Stressor/resource interactions that were determined to have
impacts that do not qualify as take under the MMPA (i.e., vessel,
aircraft, or weapons noise) were not carried forward for analysis in
the application. NMFS reviewed the Action Proponents' analysis and
conclusions on de minimis sources (i.e., those that are not likely to
result in the take of marine mammals) and finds them complete and
supportable (see section 3.7.4 of the technical report ``Quantifying
Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and
Analytical Approach for Phase IV Training and Testing'' (U.S.
Department of the Navy, 2024), hereafter referred to as the Acoustic
Impacts Technical Report).
Acoustic Stressors
Acoustic stressors include acoustic signals emitted into the water
for a specific purpose, such as sonar, other transducers (i.e., devices
that convert energy from one form to another--in this case, into sound
waves), and air guns, as well as incidental sources of broadband sound
produced as a byproduct of vessel movement, aircraft transits, use of
weapons or other deployed objects, vibratory pile extraction, and
vibratory and impact pile driving. Explosives also produce broadband
sound but are characterized separately from other acoustic sources due
to their unique hazardous characteristics. Characteristics of each of
these sound sources are described in the following sections.
To better organize and facilitate the analysis of approximately 300
sources of underwater sound used for training and testing by the Action
Proponents, including sonars and other transducers, air guns, and
explosives, a series of source classifications, or source bins, were
used. The acoustic source classification bins do not include the
broadband noise produced incidental to pile driving, vessel and
aircraft transits, weapons firing, and bow shocks. Noise produced from
vessels and aircraft are not carried forward because those activities
were found to have de minimis or no acoustic impacts, as stated above.
Of note, the source bins used in this analysis have been revised from
previous (Phase III) acoustic modeling to more efficiently group
similar sources and use the parameters of the bin for propagation,
making a comparison to previous bins impossible in most cases as some
sources are modeled at different propagation parameters. For example,
in previous analyses, non-impulsive narrowband sound sources were
grouped into bins that were defined by their acoustic properties (i.e.,
frequency, source level, beam pattern, and duty cycle) or, in some
cases, their purpose or application. In the current analysis, these
sources are binned based only on their acoustic properties and not on
their purpose or application. As such, sources that previously fell
into a single ``purpose-based'' bin now, in many cases, fall into
multiple bins while sources with similar acoustic parameters that were
previously sorted into separate bins due to different purposes now
share a bin. Therefore, the acoustic source bins used in the current
analysis do not represent a one-for-one replacement with previous bins,
making direct comparison not possible in most cases.
The use of source classification bins provides the following
benefits:
Allows new sensors or munitions to be used under existing
authorizations as long as those sources fall within the parameters of a
``bin'';
Improves efficiency of source utilization data collection
and reporting requirements anticipated under the MMPA authorizations;
Ensures that impacts are not underestimated, as all
sources within a given class are modeled as the most impactful source
(highest source level, longest duty cycle, or largest net explosive
weight (NEW)) within that bin;
Allows analyses to be conducted in a more efficient
manner, without any compromise of analytical results; and
Provides a framework to support the reallocation of source
usage (hours/explosives) between different source bins, as long as the
total numbers of takes remain within the overall analyzed and
authorized limits. This flexibility is required to support evolving
training and testing requirements, which are linked to real world
events.
Sonar and Other Transducers--
Active sonar and other transducers emit non-impulsive sound waves
into the water to detect objects, navigate safely, and communicate.
Passive sonars differ from active sound sources in that they do not
emit acoustic signals; rather, they only receive acoustic information
about the environment (i.e., listen). In this proposed rule, the terms
sonar and other transducers will be used to indicate active sound
sources unless otherwise specified.
The Action Proponents employ a variety of sonars and other
transducers to obtain and transmit information about the undersea
environment. Some examples are mid-frequency hull-mounted sonars used
to find and track enemy submarines; high-frequency small object
detection sonars used to detect mines; high-frequency underwater modems
used to transfer data over short ranges; and extremely high-frequency
(greater than 200 kilohertz (kHz)) Doppler sonars used for navigation,
like those used on commercial and private vessels. The characteristics
of these sonars and other transducers, such as source level (SL), beam
width, directivity, and frequency, depend on the purpose of the source.
Higher frequencies can carry more information or provide more
information about objects off which they reflect, but attenuate more
rapidly. Lower frequencies attenuate less rapidly, so they may detect
objects over a longer distance, but with less detail.
Propagation of sound produced underwater is highly dependent on
environmental characteristics such as bathymetry, seafloor type, water
depth, temperature, and salinity. The sound received at a particular
location will be different than near the source due to the interaction
of many factors, including propagation loss; how the sound is
reflected, refracted, or scattered; the potential for reverberation;
and interference due to multi-path propagation. In addition, absorption
greatly affects the distance over which higher-frequency sounds
propagate. The effects of these factors are explained in appendix D
(Acoustic and Explosive Impacts Supporting Information) of the 2024
HCTT Draft EIS/OEIS. Because of the complexity of analyzing sound
propagation in the ocean environment, the Action Proponents rely on
acoustic models in their environmental analyses that consider sound
source characteristics and varying ocean conditions across the HCTT
Study Area. For additional information on how propagation is accounted
for, see the Acoustic Impacts Technical Report.

[[Page 32158]]

The sound sources and platforms typically used in military
readiness activities analyzed in the application are described in
appendix A (Activity Descriptions) of the 2024 HCTT Draft EIS/OEIS.
Sonars and other transducers used to obtain and transmit information
underwater during military readiness activities generally fall into
several categories of use described below.
Anti-Submarine Warfare--
Sonar used during anti-submarine warfare training and testing would
impart the greatest amount of acoustic energy of any category of sonar
and other transducers analyzed in this proposed rule. Types of sonars
used to detect potential enemy vessels include hull-mounted, towed,
line array, sonobuoy, helicopter dipping, and torpedo sonars. In
addition, acoustic targets and decoys (countermeasures) may be deployed
to emulate the sound signatures of vessels or repeat received signals.
Most anti-submarine warfare sonars are mid-frequency (1-10 kHz)
because mid-frequency sound balances sufficient resolution to identify
targets with distance over which threats can be identified. However,
some sources may use higher or lower frequencies. Duty cycles can vary
widely, from rarely used to continuously active. Anti-submarine warfare
sonars can be wide-ranging in a search mode or highly directional in a
track mode.
Most anti-submarine warfare activities involving submarines or
submarine targets would occur in waters greater than 600 ft (182.9 m)
deep due to safety concerns about running aground at shallower depths.
Sonars used for anti-submarine warfare activities would typically be
used beyond 12 nmi (22.2 km) from shore. Exceptions include use of
dipping sonar by helicopters, pierside testing and maintenance of
systems while in port, and system checks while transiting to or from
port.
Mine Warfare, Small Object Detection, and Imaging--
Sonars used to locate mines and other small objects, as well as
those used in imaging (e.g., for hull inspections or imaging of the
seafloor), are typically high-frequency or very high-frequency. Higher
frequencies allow for greater resolution and, due to their greater
attenuation, are most effective over shorter distances. Mine detection
sonar can be deployed (towed or vessel hull-mounted) at variable depths
on moving platforms (ships, helicopters, or unmanned vehicles) to sweep
a suspected mined area. Hull-mounted anti-submarine sonars can also be
used in an object detection mode known as ``Kingfisher'' mode (MF1K)
(e.g., used on vessels when transiting to and from port), where pulse
length is shorter but pings are much closer together in both time and
space, since the vessel goes slower when operating in this mode. Sonars
used for imaging are usually used in close proximity to the area of
interest, such as pointing downward near the seafloor.
Mine detection sonar use would be concentrated in areas where
practice mines are deployed, typically in water depths less than 200 ft
(60.9 m), and at established training or testing minefields or
temporary minefields close to strategic ports and harbors. Kingfisher
mode on vessels is most likely to be used when transiting to and from
port. Sound sources used for imaging would be used throughout the HCTT
Study Area.
Navigation and Safety--
Similar to commercial and private vessels, the Action Proponents'
vessels employ navigational acoustic devices, including speed logs,
Doppler sonars for ship positioning, and fathometers. These may be in
use at any time for safe vessel operation. These sources are typically
highly directional to obtain specific navigational data.
Communication--
Sound sources used to transmit data (e.g., underwater modems),
provide location (pingers), or send a single brief release signal to
seafloor-mounted devices (acoustic release) may be used throughout the
HCTT Study Area. These sources typically have low duty cycles and are
usually only used when it is necessary to send a detectable acoustic
message.
Classification of Sonar and Other Transducers--
Sonars and other transducers are grouped into bins based on their
acoustic properties. Sonars and other transducers are now grouped into
bins based on the frequency or bandwidth, source level, duty-cycle, and
three-dimensional beam coverage. Unless stated otherwise, a reference
distance of 1 microPascal (re 1 [mu]Pa) at 1 m (3.3 ft) is used for
sonar and other transducers.
Frequency of the non-impulsive acoustic source:
[cir] Low-frequency sources operate below 1 kHz;
[cir] Mid-frequency sources operate at or above 1 kHz, up to and
including 10 kHz;
[cir] High-frequency sources operate above 10 kHz, up to and
including 100 kHz; and
[cir] Very high-frequency sources operate above 100 kHz but below
200 kHz;
Sound pressure level (SPL):
[cir] Greater than 160 decibels (dB) re 1 [mu]Pa, but less than 185
dB re 1 [mu]Pa;
[cir] Equal to 185 dB re 1 [mu]Pa and up to 205 dB re 1 [mu]Pa; and
[cir] Greater than 205 dB re 1 [mu]Pa.
Active sonar and other transducer use that was quantitatively
analyzed in the Study Area are shown in table 10.

Table 10--Sonar and Other Transducers Quantitatively Analyzed in the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Training 7- Testing 7-
Source type Source category Description Unit Training annual year total Testing annual year total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Broadband.......................... LF.................... <205 dB............... H ............... ........... 430-570 3,430
Broadband.......................... LF to MF.............. <205 dB............... H ............... ........... 2,801-2,833 19,737
Broadband.......................... LF to HF.............. <205 dB............... C 806-818 5,678 686-859 4,413
Broadband.......................... LF to HF.............. <205 dB............... H ............... ........... 1,662-2,077 11,371
Broadband.......................... MF to HF.............. <205 dB............... H 8,097-11,585 67,142 1,451-1,779 10,483
Low-frequency acoustic............. LFL................... 160 dB to 185 dB...... H ............... ........... 12 70
Low-frequency acoustic............. LFM................... 185 dB to 205 dB...... C ............... ........... 1,160-1,384 8,792
Low-frequency acoustic............. LFM................... 185 dB to 205 dB...... H 468-536 3,480 7,531-8,984 56,955
Low-frequency acoustic............. LFH................... >205 dB............... C 1,498-2,120 12,372 6,046-6,704 44,296
Low-frequency acoustic............. LFH................... >205 dB............... H 14 98 4,050-6,050 34,350
Mid-frequency acoustic............. MFL................... 160 dB to 185 dB...... H ............... ........... 12,632-14,982 92,794
Mid-frequency acoustic............. MFM................... 185 dB to 205 dB...... C 4,908-6,552 39,400 15,080-16,928 110,737
Mid-frequency acoustic............. MFM................... 185 dB to 205 dB...... H 30 210 14,381-16,081 101,064
Mid-frequency acoustic............. MFH................... >205 dB............... H 1,951-3,003 17,010 8,115-10,424 63,221
High-frequency acoustic............ HFL................... 160 dB to 185 dB...... H 60 420 21,326-22,076 151,532
High-frequency acoustic............ HFM................... 185 dB to 205 dB...... C 9 63 1,800-2,346 14,238

[[Page 32159]]

High-frequency acoustic............ HFM................... 185 dB to 205 dB...... H 3,907-5,290 31,498 12,409-13,259 89,322
High-frequency acoustic............ HFH................... >205 dB............... C 802-899 5,907 835-1,137 6,351
High-frequency acoustic............ HFH................... >205 dB............... H 2,419-2,498 17,170 1,367-1,920 10,735
Very high-frequency acoustic....... VHFL.................. 160 dB to 185 dB...... H 30 210 9,160 64,120
Very high-frequency acoustic....... VHFM.................. 185 dB to 205 dB...... H ............... ........... 96 672
Very high-frequency acoustic....... VHFH.................. >205 dB............... C ............... ........... 72-106 580
Very high-frequency acoustic....... VHFH.................. >205 dB............... H 5,458-7,862 45,418 12,544-16,824 100,648
Hull-mounted surface ship sonar.... MF1C.................. Hull-mounted surface H 796-1,406 7,404 45 314
ship sonar with duty
cycle >80%
(previously MF11).
Hull-mounted surface ship sonar.... MF1K.................. Hull-mounted surface H 455 3,183 14 91
ship sonar in
Kingfisher mode.
Hull-mounted surface ship sonar.... MF1................... Hull-mounted surface H 5,096-8,758 46,828 413-917 4,275
ship sonar.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: LF = low frequency, MF = mid frequency, HF = high frequency, dB = decibels, L = low, M = medium, H = high (e.g., MFL = mid-frequency low source
level), H = hours, C = count.

Air Guns--
Air guns are essentially stainless steel tubes charged with high-
pressure air via a compressor. An impulsive sound is generated when the
air is almost instantaneously released into the surrounding water.
Small air guns with capacities up to 60 cubic inches (in\3\; 983 cubic
centimeters (cc)) would be used during testing activities in the
offshore areas of the California Study Area and in the HRC.
Generated impulses would have short durations, typically a few
hundred milliseconds, with dominant frequencies below 1 kHz. The root-
mean-square (RMS) SPL and peak pressure (SPL peak) at a distance 1 m
(3.3 ft) from the air gun would be approximately 215 dB re 1 [mu]Pa and
227 dB re 1 [mu]Pa, respectively, if operated at the full capacity of
60 in\3\ (983 cc). The size of the air gun chamber can be adjusted,
which would result in lower SPLs and sound exposure level (SEL) per
shot. The air gun and non-explosive impulsive sources that were
quantitatively analyzed in the HCTT Study Area are shown in table 11.

Table 11--Training and Testing Air Gun Sources Quantitatively Analyzed in the Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Training Training 7- Testing 7-year
Source class category Description Bin Unit annual year total Testing annual total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Air Guns.................................. Small underwater air guns... AG C 0 0 30,432-36,780 232,068
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: AG = air guns, C = count.

Pile Driving--
Impact and vibratory pile driving and extraction would occur during
Port Damage Repair training in Port Hueneme, CA. Pile driving would not
occur at other locations within the HCTT Study Area. The pile driving
method, pile type and size, and assumptions for acoustic impact
analysis are presented in table 12. This training activity would occur
up to 12 times per year. Each training event consists of up to 7
separate modules, each which could occur up to 3 iterations during a
single event (for a maximum of 21 modules). Training events would last
a total of 30 days, of which pile driving is only anticipated to occur
for a maximum of 14 days. The training would involve the installation
and extraction 12- to 20-inch (30.5- to 50.8-cm) steel, timber, or
composite round piles, and 27.5- or 18-inch (69.9- or 45.7-cm) steel or
FRP Z-shape piles using a vibratory hammer; extraction of 12- to 20-
inch (30.5- to 50.8-cm) timber round piles and 12- to 20-inch (30.5- to
50.8 cm) steel H-piles using a vibratory hammer; and installation of
12- to 20-inch (30.5- to 50.8-cm) timber round piles, 12- to 20-inch
(30.5- to 50.8-cm) steel H-piles, and 12- to 20-inch (30.5- to 50.8-cm)
steel, timber, or composite round piles using an impact hammer table
12.

Table 12--Port Damage Repair Training Piles Quantitatively Analyzed and Associated Underwater Sound Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
SEL
Number of Peak SPL (single RMS SPL
Number of piles 7- (single strike; dB (single Unattenuated
Method Pile size and type piles year strike; re 1 strike; SPL (RMS; dB Reference
annual total dB re 1 [mu]Pa2 dB re 1 re 1 [mu]Pa)
[mu]Pa) [middot]s) [mu]Pa)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact............................ 12- to 20-inch (30 to 360 2,520 180 160 170 .............. 14-inch (36 cm) round
51 cm) timber round. timber piles
(Caltrans, 2020).
Impact............................ 12- to 20-inch (30 to 144 1,008 195 170 180 .............. 14-inch (36 cm) steel
51 cm) steel H. H-beam piles
(Caltrans, 2020).
Impact............................ 12- to 20-inch (30 to 360 2,520 203 178 189 .............. 24-inch (61 cm) steel
51 cm) steel, pipe piles
timber, or composite (Illingworth and
round. Rodkin Inc., 2007).

[[Page 32160]]

Vibratory......................... 12- to 20-inch (30 to 360 2,520 ......... .......... ......... 166 24-inch (61 cm) steel
51 cm) timber round. piles (Washington
State Department of
Transportation,
2010).
Vibratory......................... 12- to 20-inch (30 to 144 1,008 ......... .......... ......... 166 24-inch (61 cm) steel
51 cm) steel H. piles (Washington
State Department of
Transportation,
2010).
Vibratory......................... 12- to 20-inch (30 to 1,440 10,080 ......... .......... ......... 166 24-inch (61 cm) steel
51 cm) steel, piles (Washington
timber, or composite State Department of
round. Transportation,
2010).
Vibratory......................... 18- or 27.5-inch (46- 2,304 16,128 ......... .......... ......... 159 25-inch (64 cm) steel
or 70-cm) steel or sheet piles (Naval
FRP Z. Facilities
Engineering Systems
Command Southwest,
2020).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Impact method is for installation only.

Only one hammer would be operated at any given point in time; there
would not be any instances where multiple piles would be driven
simultaneously. All piles and sheets would be extracted using the
vibratory hammer.
Impact pile driving would involve the use of an impact hammer with
both it and the pile held in place by a crane. When the pile driving
starts, the hammer part of the mechanism is raised up and allowed to
fall, transferring energy to the top of the pile. The pile is thereby
driven into the sediment by a repeated series of these hammer blows.
Each blow results in an impulsive sound emanating from the length of
the pile into the water column as well as from the bottom of the pile
through the sediment. Broadband impulsive signals are produced by
impact pile driving methods, with most of the acoustic energy
concentrated below 1,000 hertz (Hz) (Hildebrand, 2009). For the
purposes of this analysis, the Action Proponents assume the impact pile
driver would generally operate on average 60 strikes per pile.
Vibratory installation and extraction would involve the use of a
vibratory hammer suspended from the crane and attached to the top of a
pile. The pile is then vibrated by hydraulic motors rotating eccentric
weights in the mechanism, causing a rapid up and down vibration in the
pile, driving the pile into the sediment. During extraction, the
vibration causes the sediment particles in contact with the pile to
lose frictional grip on the pile. The crane slowly lifts the vibratory
driver and pile until the pile is free of the sediment. In some cases,
the crane may be able to lift the pile and vibratory driver without
vibrations from the driver (i.e., dead pull), in which case no noise
would be introduced into the water. Vibratory driving and extraction
create broadband, continuous, non-impulsive noise at low source levels,
for a short duration with most of the energy dominated by lower
frequencies. Port Damage Repair training would occur in shallow water,
and sound would be transmitted on direct paths through the water, be
reflected at the water surface or bottom, or travel through seafloor
substrate. Soft substrates such as sand would absorb or attenuate the
sound more readily than hard substrates (e.g., rock), which may reflect
the acoustic wave. The predicted sound levels produced by pile driving
by method, pile size and type for Port Damage Repair training are
presented in table 12.
In addition to underwater noise, the installation and extraction of
piles also results in airborne noise in the environment, denoted dBA;
dBA is an A-weighted decibel level that represents the relative
loudness of sounds as perceived by the human ear. A-weighting gives
more value to frequencies in the middle of human hearing and less value
to frequencies at the edges as compared to a flat or unweighted decibel
level. Impact pile driving creates in-air impulsive sound about 100 dBA
re 20 [mu]Pa at a range of 15 m for 24-inch (0.61 m) steel piles
(Illingworth and Rodkin, 2016). During vibratory extraction, the three
aspects that generate airborne noise are the crane, the power plant,
and the vibratory extractor. The average sound level recorded in air
during vibratory extraction was about 85 dBA re 20 [mu]Pa (94 dB re 20
[mu]Pa) within a range of 32.8-49.2 ft (10-15 m) (Illingworth and
Rodkin, 2015).
Explosive Stressors
This section describes the characteristics of explosions during
military readiness activities. The activities analyzed in the
application that use explosives are described in appendix A (Activity
Descriptions) of the 2024 HCTT Draft EIS/OEIS, and terminology and
metrics used when describing explosives in the application are in
appendix D (Acoustic and Explosive Impacts Supporting Information) of
the 2024 HCTT Draft EIS/OEIS.
The near-instantaneous rise from ambient to an extremely high peak
pressure is what makes an explosive shock wave potentially damaging.
Farther from an explosive, the peak pressures decay and the explosive
waves propagate as an impulsive, broadband sound. Several parameters
influence the effect of an explosive: the weight of the explosive
warhead, the type of explosive material, the boundaries and
characteristics of the propagation medium, and the detonation depth in
water. The NEW, the explosive power of a charge expressed as the
equivalent weight of trinitrotoluene (commonly referred to as TNT),
accounts for the first two parameters.
Explosions in Water--
Explosive detonations during military readiness activities are
associated with high-explosive munitions, including, but not limited to
bombs, missiles,

[[Page 32161]]

rockets, naval gun shells, torpedoes, mines, demolition charges, and
explosive sonobuoys. Explosive detonations during military readiness
activities involving the use of high-explosive munitions, including
bombs, missiles, and naval gun shells, would occur in the air or near
the water's surface. Explosive detonations associated with torpedoes
and explosive sonobuoys would occur in the water column; mines and
demolition charges would be detonated in the water column or on the
ocean floor. The Coast Guard usage of explosives is limited to medium
and large-caliber munitions used during gunnery exercises. Most
detonations would occur in waters greater than 200 ft (60.9 m) in depth
and greater than 3 nmi (5.6 km) from shore, although some mine warfare,
demolition, and some testing detonations would occur in shallow water
close to shore. The Army usage of explosives is limited to large-
caliber projectiles used during shore-to-surface artillery and missile
exercises, and all projectiles will impact beyond 3 nmi (5.6 km) from
shore.
To better organize and facilitate the analysis of explosives used
by the Action Proponents during military readiness activities that
would detonate in water or at the water surface, explosive
classification bins were developed. The use of explosive classification
bins provides the same benefits as described for acoustic source
classification bins in the Sonar and Other Transducers section.
Explosives detonated in water are binned by NEW. Table 13 shows
explosives use that was quantitatively analyzed in the Study Area. A
range of annual use indicates that occurrence is anticipated to vary
annually, consistent with the variation in the number of annual
activities described in chapter 2 (Description of Proposed Action and
Alternatives) of the 2024 HCTT Draft EIS/OEIS. The 7-year total takes
that variability into account.

Table 13--Explosive Sources Quantitatively Analyzed Proposed for Use Underwater or at the Water Surface
--------------------------------------------------------------------------------------------------------------------------------------------------------
Coast Coast
Net explosive Example explosive Navy training Navy Guard Guard Army Army Navy testing Navy
Bin weight (lb.) source annual training training training training training annual testing 7-
7-year annual 7-year annual 7-year year
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.......... 0.1-0.25........... Medium-caliber 1,750-4,303 19,911 ......... ......... ......... ......... 7,305-7,430 51,510
projectile.
E2.......... >0.25-0.5.......... Medium-caliber 2,950-3,000 20,800 ......... ......... ......... ......... .............. .........
projectile.
E3.......... >0.5-2.5........... 2.75-inch (7 cm) 5,438-5,720 38,912 150 1,050 ......... ......... 4,744-6,568 36,704
rockets.
E4.......... >2.5-5............. Mine neutralization 179-190 1,286 ......... ......... ......... ......... 1,324-2,624 18,352
charge.
E5.......... >5-10.............. 5-inch (12.7 cm) 5,059-5,984 38,188 ......... ......... ......... ......... 2,024-2,676 16,732
projectile.
E6.......... >10-20............. Hellfire missile... 1,693-1,757 12,043 ......... ......... 600 4,200 144-148 1,020
E7.......... >20-60............. Demo block/shaped 115-190 1,030 ......... ......... ......... ......... 549-622 2,322
charge.
E8.......... >60-100............ Lightweight torpedo 3-5 27 ......... ......... ......... ......... 213-234 1,552
E9.......... >100-250........... 500 lb. (228 kg) 278-300 2,015 ......... ......... 108 756 111-115 789
bomb.
E10......... >250-500........... Harpoon missile.... 89 620 ......... ......... ......... ......... 13 91
E11......... >500-675........... Heavyweight Torpedo 7-11 61 ......... ......... ......... ......... 1-2 8
E12......... >675-1,000......... 2,000 lb. (907.2 17-19 125 ......... ......... ......... ......... .............. .........
kg) bomb.
E13......... >1,000-1,740....... Underwater 6 42 ......... ......... ......... ......... .............. .........
demolitions--large
area clearance.
E16......... 10,000............. Ship shock .............. ......... ......... ......... ......... ......... 0-3 3
detonation.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: > = greater than, in. = inch, lb. = pound, kg = kilogram.

Propagation of explosive pressure waves in water is highly
dependent on environmental characteristics such as bathymetry, seafloor
type, water depth, temperature, and salinity, which affect how the
pressure waves are reflected, refracted, or scattered; the potential
for reverberation; and interference due to multi-path propagation. In
addition, absorption greatly affects the distance over which higher-
frequency components of explosive broadband noise can propagate.
Appendix D (Acoustic and Explosive Impacts Supporting Information) of
the 2024 HCTT Draft EIS/OEIS explains the characteristics of explosive
detonations and how the above factors affect the propagation of
explosive energy in the water. Because of the complexity of analyzing
sound propagation in the ocean environment, the Action Proponents rely
on acoustic models in their environmental analyses that consider sound
source characteristics and varying ocean conditions across the Study
Area.
In-Air Acoustic Stressors
The proposed military readiness activities would generate missile
and aerial target launch noise from locations on SNI (California),
noise from missile and aerial target launches at the PMRF
(Kaua[revaps]i, Hawaii), and artillery firing noise from shore to
surface gunnery at San Clemente Island and PMRF. Table 14 shows launch
noise that was quantitatively analyzed in the HCTT Study Area.
Noise from target and missile launches from land at SNI and PMRF
may disturb hauled-out pinnipeds. At SNI, this disturbance has been
documented over nearly two decades of monitoring and reporting of those
activities (U.S. Department of the Navy, 2020, 2022, 2023).
At PMRF, Hawaiian monk seals are known to haul out on a beach near
the missile launch complex. If a seal is hauled out during a missile or
aerial target launch, the seal may react to the noise and exhibit a
behavioral response that may qualify as harassment (e.g., flushing into
the water). (Though, of note, behavioral disturbance of monk seals
(e.g., flushing or other disturbance) has not been observed due to
these activities.) Currently, if a monk seal is hauled out on the beach
(typically within approximately 1,000 ft (304.8 m) of the launch site)
prior to a missile launch, the launch is halted or postponed until the
seal has left the beach.

[[Page 32162]]

Table 14--Proposed Launches Analyzed Within the HCTT Study Area
----------------------------------------------------------------------------------------------------------------
Navy training Navy training Navy testing Navy testing 7-
Launch type Location annual 7-year total annual year total
----------------------------------------------------------------------------------------------------------------
Missiles and Aerial Targets... SNI (PMSR)...... 0 0 40 280
Missiles and Aerial Targets... PMRF............ 22 154 13 91
Artillery..................... PMRF............ 900 6,300 0 0
----------------------------------------------------------------------------------------------------------------
Note: SNI = San Nicolas Island, PMSR = Point Mugu Sea Range, PMRF = Pacific Missile Range Facility.

Vessel Strike
NMFS also considered the likelihood that vessel movement during
military readiness activities could result in an incidental, but not
intentional, strike of a marine mammal in the HCTT Study Area, which
has the potential to result in serious injury or mortality. Vessel
strikes are not specific to any specific military readiness activity
but rather, a limited, sporadic, and incidental result of the Action
Proponents' vessel movement during military readiness activities within
the Study Area. Vessel strikes from commercial, recreational, and
military vessels are known to seriously injure and occasionally kill
cetaceans (Abramson et al., 2011; Berman-Kowalewski et al., 2010;
Calambokidis, 2012; Crum et al., 2019; Douglas et al., 2008; Laggner
2009; Van der Hoop et al., 2012; Van der Hoop et al., 2013), although
reviews of the literature on vessel strikes mainly involve collisions
between commercial vessels and whales (Jensen and Silber, 2003, Laist
et al., 2001). Vessel speed, size, and mass are all important factors
in determining both the potential likelihood and impacts of a vessel
strike to marine mammals (Blondin et al. 2025; Conn and Silber, 2013;
Garrison et al. 2025; Gende et al., 2011; Redfern et al., 2019; Silber
et al., 2010; Szesciorka et al., 2019; Vanderlaan and Taggart, 2007;
Wiley et al., 2016). For large vessels, speed and angle of approach can
influence the severity of a strike.
The Action Proponents' vessels transit at speeds that are optimal
for fuel conservation or to meet training and testing requirements.
From unpublished Navy data, average speed for large (greater than 350
ft (107 m) Navy ships in Southern California and Hawaii from 2016-2023
varied from 10 to 15 kn (18.5 to 27.8 km/hr) in offshore waters greater
than 12 nmi from land and from 5 to 10 kn (9.3 to 18.5 km/hr) closer to
the coast (less than 12 nmi; Navy 2021, unpublished data). Small craft
(for purposes of this analysis, less than 59 ft (18 m) in length) have
much more variable speeds (0 to 50 kn (0 to 92.6 km/hr), dependent on
the activity). Submarines generally operate at speeds in the range of 8
to 13 kn (14.8 to 24.1 km per hour). Similar patterns are anticipated
in the HCTT Study Area. A full description of the Action Proponents'
vessels proposed for use during military readiness activities can be
found in Chapter 2 (Description of Proposed Action and Alternatives) of
the 2024 HCTT Draft EIS/OEIS.
While these speeds for large Navy vessels are representative of
most events, some of the Action Proponents' vessels may need to
temporarily operate outside of these parameters. For example, to
produce the required relative wind speed over the flight deck, an
aircraft carrier engaged in flight operations must adjust its speed
through the water accordingly. There are specific events, including
high speed tests of newly constructed vessels, where the Action
Proponents' vessel would operate at higher speeds. By comparison, there
are other instances when the Action Proponents vessel would be stopped
or moving slowly ahead to maintain steerage, such as launch and
recovery of a small rigid hull inflatable boat; vessel boarding,
search, and seizure training events; or retrieval of a target.
Large Navy vessels (>400 ft (121.9 m)) and Coast Guard vessels
within the offshore areas of range complexes and testing ranges operate
differently from commercial vessels, which may reduce potential vessel
strikes of large whales. Surface ships operated by or for the Navy have
multiple personnel assigned to stand watch at all times, when a ship or
surfaced submarine is moving through the water (underway). A primary
duty of personnel standing watch on surface ships is to detect and
report all objects and disturbances sighted in the water that may
indicate a threat to the vessel and its crew, such as debris, a
periscope, surfaced submarine, or surface disturbance. Per vessel
safety requirements, personnel standing watch also report any marine
mammals sighted in the path of the vessel as a standard collision
avoidance procedure. All vessels proceed at a safe speed so they can
take proper and effective action to avoid a collision with any sighted
object or disturbance, and can stop within a distance appropriate to
the prevailing circumstances and conditions. As described in the
Standard Operating Procedures section, the Action Proponents utilize
Lookouts to avoid collisions, and Lookouts are trained to spot marine
mammals so that vessels may change course or take other appropriate
action to avoid collisions. Despite the precautions, should a vessel
strike occur, NMFS anticipates it would likely result in incidental
take in the form of serious injury and/or mortality, though it is
possible that it could result in a non-serious injury (Level A
harassment). Accordingly, for the purposes of the analysis, NMFS
assumes that any vessel strike would result in serious injury or
mortality.
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation Measures section, Proposed Monitoring section, and Proposed
Reporting section).
Description of Marine Mammals and Their Habitat in the Area of
Specified Activities
Marine mammal species and their associated stocks that have the
potential to occur in the HCTT Study Area are presented in table 15
along with each stock's Endangered Species Act (ESA) and MMPA statuses,
abundance estimate and associated coefficient of variation (CV) value,
minimum abundance estimate, potential biological removal (PBR), annual
M/SI, and potential occurrence in the HCTT Study Area. The Action
Proponents request authorization to take individuals of 40 species (79
stocks) by Level A and Level B harassment incidental to military
readiness activities from the use of sonar and other transducers, in-
water detonations, air guns, missile and target launch noise, pile
driving/extraction, and vessel movement in the HCTT Study Area.
Currently, the humpback whale (Central America and Mexico Distinct
Population Segments (DPSs)), killer whale (Eastern North Southern
Resident DPS), false killer whale (Main Hawaiian Islands Insular DPS),
and Hawaiian monk seal have critical habitat designated under the ESA
in the HCTT Study Area (see Critical Habitat section below).

[[Page 32163]]

Sections 3 and 4 and appendix B (Marine Mammal Supplemental
Information) of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history of the potentially affected species. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs) (https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website at: https://www.fisheries.noaa.gov/find-species. Additional information on the
general biology and ecology of marine mammals is included in the 2024
HCTT Draft EIS/OEIS. Table 15 incorporates the best available science,
including data from the 2023 Pacific and Alaska Marine Mammal Stock
Assessment Reports (Carretta et al., 2024; Young et al., 2024) (see
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments), and 2024 draft SARs, as well as
monitoring data from the Navy's marine mammal research efforts.

Table 15--Marine Mammal Occurrence Within the HCTT Study Area \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ SI \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
Gray whale...................... Eschrichtius robustus.. Eastern North Pacific.. -, -, N 25,960 (0.05, 25,849, 801 131
2016).
Gray whale...................... Eschrichtius robustus.. Western North Pacific.. E, D, Y 290 (N/A, 271, 2016).. 0.12 UNK
Family Balaenopteridae (rorquals):
Blue whale...................... Balaenoptera musculus.. Central North Pacific.. E, D, Y 133 (1.09, 63, 2010).. 0.1 0
Blue whale...................... Balaenoptera musculus.. Eastern North Pacific.. E, D, Y 1,898 (0.085, 1,767, 4.1 >=18.6
2018).
Bryde's whale................... Balaenoptera edeni..... Eastern Tropical -, -, N UNK (UNK, UNK, N/A)... UND UNK
Pacific.
Bryde's whale................... Balaenoptera edeni..... Hawaii................. -, -, N 791 (0.29, 623, 2020). 6.2 0
Fin whale....................... Balaenoptera physalus.. Hawaii................. E, D, Y 203 (0.99, 101, 2017). 0.2 0
Fin whale....................... Balaenoptera physalus California/Oregon/ E, D, Y 11,065 (0.405, 7,970, 80 >=43.4
velifera. Washington. 2018).
Humpback whale.................. Megaptera novaeangliae. Central America/ E, D, Y 1,496 (0.171, 1,284, 3.5 14.9
Southern Mexico- 2021).
California-Oregon-
Washington \5\.
Humpback whale.................. Megaptera novaeangliae. Mainland Mexico- T, D, Y 3,477 (0.101, 3,185, 43 22
California-Oregon- 2018).
Washington \5\.
Humpback whale.................. Megaptera novaeangliae. Hawaii................. -, -, N 11,278 (0.56, 7,265, 127 27.09
2020).
Minke whale..................... Balaenoptera Hawaii................. -, -, N 438 (1.05, 212, 2017). 2.1 0
acutorostrata.
Minke whale..................... Balaenoptera California/Oregon/ -, -, N 915 (0.792, 509, 2018) 4.1 >=0.19
acutorostrata. Washington.
Sei whale....................... Balaenoptera borealis.. Hawaii................. E, D, Y 391 (0.9, 204, 2010).. 0.4 0.2
Sei whale....................... Balaenoptera borealis.. Eastern North Pacific.. E, D, Y 864 (0.40, 625, 2014). 1.25 UNK
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm whale..................... Physeter macrocephalus. Hawaii................. E, D, Y 5,707 (0.23, 4,486, 18 0
2017).
Sperm whale..................... Physeter macrocephalus. California/Oregon/ E, D, Y 2,606 (0.135, 2,011, 4 0.52
Washington. 2018).
Family Kogiidae:
Dwarf sperm whale............... Kogia sima............. Hawaii................. -, -, N UNK (UNK, UNK, 2017).. UND 0
Dwarf sperm whale............... Kogia sima............. California/Oregon/ -, -, N UNK (UNK, UNK, 2014).. UND 0
Washington.
Pygmy sperm whale............... Kogia breviceps........ Hawaii................. -, -, N 42,083 (0.64, 25,695, 257 0
2017).
Pygmy sperm whale............... Kogia breviceps........ California/Oregon/ -, -, N 4,111 (1.12, 1,924, 19.2 0
Washington. 2014).
Family Ziphiidae (beaked whales):
Baird's beaked whale............ Berardius bairdii...... California/Oregon/ -, -, N 1,363 (0.53, 894, 8.9 >=0.2
Washington. 2018).
Blainville's beaked whale....... Mesoplodon densirostris Hawaii................. -, -, N 1,132 (0.99, 564, 5.6 0
2017).
Goose-beaked whale.............. Ziphius cavirostris.... Hawaii................. -, -, N 4,431 (0.41, 3,180, 32 0
2017).
Goose-beaked whale.............. Ziphius cavirostris.... California/Oregon/ -, -, N 5,454 (0.27, 4,214, 42 <0.1
Washington. 2016).
Longman's beaked whale.......... Indopacetus pacificus.. Hawaii................. -, -, N 2,550 (0.67, 1,527, 15 0
2017).
Mesoplodont beaked whale........ Mesoplodon spp. \6\.... California/Oregon/ -, -, N 3,044 (0.54, 1,967, 20 0.1
Washington. 2014).
Family Delphinidae:
False killer whale.............. Pseudorca crassidens... Main Hawaiian Islands E, D, Y 167 (0.14, 149, 2015). 0.3 0.1
Insular.
False killer whale.............. Pseudorca crassidens... Northwest Hawaiian -, -, N 477 (1.71, 178, 2017). 1.43 0.16
Islands.
False killer whale.............. Pseudorca crassidens... Hawaii Pelagic......... -, -, Y 5,528 (0.35, 4,152, 36 47
2017).
False killer whale.............. Pseudorca crassidens... Baja California N/A 2.962 (0.71, N/A, N/A) N/A N/A
Peninsula Mexico \7\.

[[Page 32164]]

Killer whale.................... Orcinus orca........... Hawaii................. -, -, N 161 (1.06, 78, 2017).. 0.8 0
Killer whale.................... Orcinus orca........... Eastern North Pacific -, -, N 300 (0.1, 276, 2012).. 2.8 0
Offshore.
Killer whale.................... Orcinus orca........... Eastern North Pacific E, D, Y 75 (N/A, 75, 2023).... 0.13 0
Southern Resident.
Killer whale.................... Orcinus orca........... West Coast Transient... -, -, N 349 (N/A, 349, 2018).. 3.5 0.4
Melon-headed whale.............. Peponocephala electra.. Hawaiian Islands....... -, -, N 40,647 (0.74, 23,301 233 0
\3\ 2017).
Melon-headed whale.............. Peponocephala electra.. Kohala Resident -, -, N UNK (UNK, UNK, 2017).. UND 0
(Hawaii).
Pygmy killer whale.............. Feresa attenuata....... Hawaii................. -, -, N 10,328 (0.75, 5,885, 59 0
2017).
Pygmy killer whale.............. Feresa attenuata....... California-Baja N/A 229 (1.11, N/A, N/A).. N/A N/A
California Peninsula
Mexico \7\.
Short-finned pilot whale........ Globicephala Hawaii................. -, -, N 19,242 (0.23, 15,894, 159 0.2
macrorhynchus. 2020).
Short-finned pilot whale........ Globicephala California/Oregon/ -, -, N 836 (0.79, 466, 2014). 4.5 1.2
macrorhynchus. Washington.
Bottlenose dolphin.............. Tursiops truncatus..... Maui Nui............... -, -, N 64 (0.15, 56, 2018)... 0.6 UNK
Bottlenose dolphin.............. Tursiops truncatus..... Hawaii Island.......... -, -, N 136 (0.43, 96, 2018).. 1 >0.2
Bottlenose dolphin.............. Tursiops truncatus..... Hawaii Pelagic......... -, -, N 24,669 (0.57, 15,783, 158 0
2020).
Bottlenose dolphin.............. Tursiops truncatus..... Kaua[revaps]i/ -, -, N 112 (0.24, 92, 2018).. 0.9 UNK
Ni[revaps]ihau.
Bottlenose dolphin.............. Tursiops truncatus..... O[revaps]ahu........... -, -, N 112 (0.17, 97, 2017).. 1 UNK
Bottlenose dolphin.............. Tursiops truncatus..... California Coastal..... -, -, N 453 (0.06, 346, 2011). 2.7 >=2.0
Bottlenose dolphin.............. Tursiops truncatus..... California/Oregon/ -, -, N 3,477 (0.696, 2,048, 19.7 >=0.82
Washington Offshore. 2018).
Fraser's dolphin................ Lagenodelphis hosei.... Hawaii................. -, -, N 40,960 (0.7, 24,068, 241 0
2017).
Long-beaked common dolphin...... Delphinus delphis California............. -, -, N 83,379 (0.216, 69,636, 668 >=29.7
bairdii. 2018).
Northern right whale dolphin.... Lissodelphis borealis.. California/Oregon/ -, -, N 29,285 (0.72, 17,024, 163 >=6.6
Washington. 2018).
Pacific white-sided dolphin..... Lagenorhynchus California/Oregon/ -, -, N 34,999 (0.222, 29,090, 279 7
obliquidens. Washington. 2018).
Pantropical spotted dolphin..... Stenella attenuata..... Maui Nui............... -, -, N UNK (UNK, UNK, N/A)... UND UNK
Pantropical spotted dolphin..... Stenella attenuata..... Hawaii Island.......... -, -, N UNK (UNK, UNK, N/A)... UND UNK
Pantropical spotted dolphin..... Stenella attenuata..... Hawaii Pelagic......... -, -, N 67,313 (0.27, 53,839, 538 0
2020).
Pantropical spotted dolphin..... Stenella attenuata..... O[revaps]ahu........... -, -, N UNK (UNK, UNK, N/A)... UND UNK
Pantropical spotted dolphin..... Stenella attenuata..... Baja California N/A 105,416 (0.46, N/A, N/ N/A N/A
Peninsula Mexico \7\. A).
Risso's dolphin................. Grampus griseus........ Hawaii................. -, -, N 6,979 (0.29, 5,283, 53 0
2020).
Risso's dolphin................. Grampus griseus........ California/Oregon/ -, -, N 6,336 (0.32, 4,817, 46 >=3.7
Washington. 2014).
Rough-toothed dolphin........... Steno bredanensis...... Hawaii................. -, -, N 83,915 (0.49, 56,782, 511 3.2
2017).
Short-beaked common dolphin..... Delphinus delphis...... California/Oregon/ -, -, N 1,056,308 (0.21, 8,889 >=30.5
Washington. 888,971, 2018).
Spinner dolphin................. Stenella longirostris.. Hawaii Pelagic......... -, -, N UNK (UNK, UNK, 2010).. UND 0
Spinner dolphin................. Stenella longirostris.. Hawaii Island.......... -, -, N 665 (0.09, 617, 2012). 6.2 >=1.0
Spinner dolphin................. Stenella longirostris.. Kaua[revaps]i/ -, -, N N/A (N/A, N/A, 2005).. UND UNK
Ni[revaps]ihau.
Spinner dolphin................. Stenella longirostris.. Midway Atoll/Kure...... -, -, N UNK (UNK, UNK, 2010).. UND UNK
Spinner dolphin................. Stenella longirostris.. O[revaps]ahu/4 Islands -, -, N N/A (N/A, N/A, 2007).. UND >=0.4
Region.
Spinner dolphin................. Stenella longirostris.. Pearl and Hermes....... -, -, N UNK (UNK, UNK, N/A)... UND UNK
Spinner dolphin................. Stenella coeruleoalba.. Hawaii Pelagic......... -, -, N 64,343 (0.28, 51,055, 511 0
2020).
Spinner dolphin................. Stenella coeruleoalba.. California/Oregon/ -, -, N 29,988 (0.3, 23,448, 225 >=4
Washington. 2018).
Family Phocoenidae (porpoises):
Dall's porpoise................. Phocoenoides dalli..... California/Oregon/ -, -, N 16,498 (0.61, 10,286, 99 >=0.66
Washington. 2018).
Harbor porpoise................. Phocoena phocoena...... Monterey Bay........... -, -, N 3,760 (0.561, 2,421, 35 >=0.2
2013).
Harbor porpoise................. Phocoena phocoena...... Morro Bay.............. -, -, N 4,191 (0.56, 2,698, 65 0
2012).
Harbor porpoise................. Phocoena phocoena...... Northern California/ -, -, N 15,303 (0.575, 9,759, 195 0
Southern Oregon. 2022).
Harbor porpoise................. Phocoena phocoena...... San Francisco/Russian -, -, N 7,777 (0.62, 4,811, 73 >=0.4
River. 2017).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
California sea lion............. Zalophus californianus. U.S.................... -, -, N 257,606 (N/A, 233,515, 14,011 >321
2014).
Guadalupe fur seal.............. Arctocephalus townsendi Mexico................. T, D, Y 68,850 (N/A, 57,199, 1,959 >=10.0
2013).
Northern fur seal............... Callorhinus ursinus.... Eastern Pacific........ -, D, Y 612,765 (0.2, 518,651, 11,151 296
2022).

[[Page 32165]]

Northern fur seal............... Callorhinus ursinus.... California............. -, -, N 19,634 (N/A, 8,788, 527 >=1.2
2022).
Steller sea lion................ Eumetopias jubatus..... Eastern................ -, -, N 36,308 (N/A, 36,308, 2,178 93
2022).
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina......... California............. -, -, N 30,968 (N/A, 27,348, 1,641 43
2012).
Hawaiian monk seal.............. Neomonachus Hawaii................. E, D, Y 1,605 (0.05, 1,508, 5 >=4.8
schauinslandi. 2022).
Northern elephant seal.......... Mirounga angustirostris California Breeding.... -, -, N 194,907 (N/A, 88,794, 5,328 11
2023).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UND = Undetermined, UNK = Unknown. Unless otherwise noted, abundance estimates are from the final 2022 Pacific stock
assessment report (Carretta et al., 2024; Carretta et al., 2023b), the draft 2023 Pacific stock assessment report (Carretta et al., 2024), or the
Alaska stock assessment reports (Young, 2024).
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
(https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
\5\ Humpback whales in the Central America/Southern Mexico-California-Oregon-Washington Stock make up the endangered Central America DPS, and humpback
whales in the Mainland Mexico-California-Oregon-Washington Stock are part of the threatened Mexico DPS, along with whales from the Mexico-North
Pacific Stock, which do not occur in the Study Area.
\6\ Mesoplodont beaked whales are analyzed as a group due to insufficient data available to estimate species-specific densities.
\7\ The Baja California Peninsula Mexico and California-Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin,
and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were
derived to support the Navy's analysis.

Species Not Included in the Analysis

The species carried forward for analysis (and described in table
15) are those likely to be found in the HCTT Study Area based on the
most recent data available, and do not include species that may have
once inhabited or transited the area but have not been sighted in
recent years (e.g., species which were extirpated from factors such as
19th and 20th century commercial exploitation). North Pacific right
whale may be present in the northeast Pacific Ocean, but has an
extremely low probability of presence in the HCTT Study Area. It is
considered extralimital (i.e., not anticipated to occur in the Study
Area) and was not included in the analysis.
One species of marine mammal, the southern sea otter, occurs in the
HCTT Study Area but is managed by the U.S. Fish and Wildlife Service
(U.S. FWS) and thus are not considered further in this analysis.
Below, we consider additional information about the marine mammals
in the area of the specified activities that informs our analysis, such
as identifying known areas of important habitat or behaviors, or where
unusual mortality events have been designated.

Critical Habitat

Currently, the humpback whale (Central America and Mexico DPSs),
killer whale (Eastern North Pacific Southern Resident DPS), false
killer whale (Main Hawaiian Islands Insular DPS), and Hawaiian monk
seal have ESA-designated critical habitat in the HCTT Study Area.
Humpback Whale
On April 21, 2021, NMFS designated critical habitat for the
endangered Western North Pacific DPS, the endangered Central America
DPS, and the threatened Mexico DPS of humpback whales (86 FR 21082).
Areas proposed as critical habitat include specific marine areas
located off the coasts of California, Oregon, Washington, and Alaska.
Designated critical habitat for the Central America DPS overlaps the
NOCAL Range Complex (Units 15, 16, and 17), as well as PMSR and the
northern portion of the SOCAL Range Complex (Units 17 and 18). These
areas are essential for humpback whale foraging and migration. One of
the proposed critical habitat areas, critical habitat Unit 19, would
have also overlapped with the SOCAL range in the HSTT Study Area but
was excluded after consideration of potential national security and
economic impacts of designation.
NMFS, in the final rule designating critical habitat for humpback
whales, identified prey species, primarily euphausiids and small
pelagic schooling fishes of sufficient quality, abundance, and
accessibility within humpback whale feeding areas to support feeding
and population growth, as an essential habitat feature. NMFS, through a
critical habitat review team (CHRT), also considered inclusion of
migratory corridors and passage features, as well as sound and the
soundscape, as essential habitat features. NMFS did not include either
in the final critical habitat; however, as the CHRT concluded that the
best available science did not allow for identification of any
consistently used migratory corridors or definition of any physical,
essential migratory or passage conditions for whales transiting between
or within habitats of the three DPSs. Regardless of whether critical
habitat is designated for a particular area, NMFS has considered all
applicable information regarding marine mammals and their habitat in
the analysis supporting these proposed regulations.
Killer Whale
NMFS designated critical habitat for the Southern Resident killer
whale DPS on November 29, 2006 (71 FR 69054) in inland waters of
Washington State, and on August 2, 2021, revised the designation by
designating six additional coastal critical habitat areas along the
U.S. West Coast (86 FR 41668). The HCTT Study Area overlaps two of the
three continuous sections off the California coast: the North Central
CA Coast Area and the Monterey Bay Area. Based on the natural history
of the Southern Resident killer whales and their habitat needs, NMFS
identified physical or biological features essential to the
conservation of the Southern

[[Page 32166]]

Resident killer whale DPS: (1) water quality to support growth and
development; (2) prey species of sufficient quantity, quality, and
availability to support individual growth, reproduction, and
development, as well as overall population growth; and (3) passage
conditions to allow for migration, resting, and foraging.
False Killer Whale (Main Hawaiian Island Insular DPS)
Critical habitat for the ESA-listed Main Hawaiian Islands insular
false killer whale DPS was finalized in July 2018 (83 FR 35062, July
24, 2018) designating waters from the 45 m depth contour to the 3,200 m
depth contour around the main Hawaiian Islands from Ni[revaps]ihau east
to Hawaii. This designation does not include most bays, harbors, or
coastal in-water structures. NMFS excluded 14 areas. The total area
designated was approximately 45,504 square kilometers (km\2\; 13,267
square nautical miles (nmi\2\)) of marine habitat. Critical habitat for
the main Hawaiian Islands insular DPS of false killer whale entirely
overlaps the HRC.
Main Hawaiian Islands insular false killer whales are island-
associated whales that rely entirely on the productive submerged
habitat of the main Hawaiian Islands to support all of their life-
history stages. Island-associated marine habitat for Main Hawaiian
Islands insular false killer whale is the only essential feature of the
critical habitat. The following characteristics of this habitat support
insular false killer whales' ability to travel, forage, communicate,
and move freely around and among the waters surrounding the main
Hawaiian Islands: (1) adequate space for movement and use within shelf
and slope habitat; (2) prey species of sufficient quantity, quality,
and availability to support individual growth, reproduction, and
development, as well as overall population growth; (3) waters free of
pollutants of a type and amount harmful to Main Hawaiian Islands
insular false killer whales; and (4) sound levels that would not
significantly impair false killer whales' use or occupancy.
Hawaiian Monk Seal
Critical habitat for Hawaiian monk seals was designated in 1986 (51
FR 16047, April 30, 1986) and later revised in 1988 (53 FR 18988, May
26, 1988) and in 2015 (80 FR 50925, August 21, 2015). In the
Northwestern Hawaiian Islands Hawaiian monk seal critical habitat
includes all beach areas, sand spits and islets, including all beach
crest vegetation to its deepest extent inland as well as the seafloor
and marine habitat 10 m in height above the seafloor from the shoreline
out to the 200 m depth contour around Kure Atoll
(H[omacr]lanik[umacr]), Midway Atoll (Kuaihelani), Pearl and Hermes
Reef (Manawai), Lisianski Island (Kapou), Laysan Island (Kamole), Maro
Reef (Kamokuokamohoali[revaps]i), Gardner Pinnacles
([revaps][revaps][Omacr]n[umacr]nui), French Frigate Shoals (Lalo),
Necker Island (Mokumanamana) and Nihoa Island. In the main Hawaiian
Islands, Hawaiian monk seal critical habitat includes the seafloor and
marine habitat to 10 m above the seafloor from the 200 m depth contour
through the shoreline and extending into terrestrial habitat 5 m inland
from the shoreline between identified boundary points around Kaula
Island (includes marine habitat only), Ni[revaps]ihau (includes marine
habitat from 10 m-200 m in depth), Kaua[revaps]i, O[revaps]ahu, Maui
Nui (including Kaho[revaps]olawe, L[amacr]na[revaps]i, Maui, and
Moloka[revaps]i), and Hawaii Island. A portion of the critical habitat
overlaps the HRC.
The essential features of Hawaiian monk seal critical habitat are:
(1) terrestrial areas and adjacent shallow, sheltered aquatic areas
with characteristics preferred by monk seals for pupping and nursing;
(2) marine areas from 0 to 200 m in depth that support adequate prey
quality and quantity for juvenile and adult monk seal foraging; and (3)
significant areas used by monk seals for hauling out, resting or
molting.

Biologically Important Areas

Ferguson et al. (2015) identified Biologically Important Areas
(BIAs) within U.S. waters of the West Coast (Calambokidis et al. 2015)
and in Hawaii (Baird et al. 2015), which represent areas and times in
which cetaceans are known to concentrate in areas of known importance
for activities related to reproduction, feeding, and migration, or
areas where small and resident populations are known to occur. Unlike
ESA critical habitat, these areas are not formally designated pursuant
to any statute or law, but are a compilation of the best available
science intended to inform impact and mitigation analyses. An
interactive map of the BIAs is available at: https://oceannoise.noaa.gov/biologically-important-areas. In some cases,
additional, or newer, information regarding known feeding, breeding, or
migratory areas is available and has been used to update these BIAs (as
cited below), and a summary of all of the BIAs is included below.
The West Coast and Hawaii BIAs were updated in 2024 (Calambokidis
et al.) and 2023 (Kratofil et al.), respectively (referred to as BIA II
herein). Calambokidis et al. (2024) and Kratofil et al. (2023) use a
new scoring system described here and in Harrison et al. (2023).
Experts identified an overall Importance Score for each BIA that
considers: (1) ``Intensity''--the intensity and characteristics
underlying an area's identification as a BIA; and (2) ``Data
Support''--the quantity, quality, and type of information, and
associated uncertainties, upon which the BIA delineation and scoring
depends. Importance Scores range from 1 to 3, with a higher score
representing an area of higher intensity and data support. Each BIA
identified in BIA II is also scored for boundary uncertainty and
spatiotemporal variability (dynamic, ephemeral, or static).
Additionally, BIA II includes hierarchical BIAs for some species and
stocks where a higher intensity score is appropriate for a smaller core
area(s) (child BIA) within a larger BIA unit (parent BIA).
The Hawaii Study Area overlaps BIAs for small and resident
populations of the following species: spinner dolphin, short-finned
pilot whale, rough-toothed dolphin, pygmy killer whale, pantropical
spotted dolphin, melon-headed whale, false killer whale, dwarf sperm
whale, goose-beaked whale, common bottlenose dolphin, and Blainville's
beaked whale. Further, the Hawaii Study Area overlaps updated BIAs for
humpback whale reproduction (Kratofil et al. 2023). The California
Study Area overlaps feeding BIAs for blue whale, fin whale, and
humpback whale in SOCAL. Additionally, it overlaps a reproductive BIA
as well as northbound and southbound migratory BIAs for gray whale
(Calambokidis et al. 2024). Table 16 describes each BIA that overlaps
the HCTT Study Area and the scores for the above criteria.

[[Page 32167]]

Table 16--BIAs Overlapping the HCTT Study Area
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Figure in
action Data
Species BIA type Parent/child/non- BIA name Effective months BIA area proponents' Importance Intensity support Boundary Spatiotemporal Transboundary across
hierarchical (km\2\) LOA score score score certainty variability
application
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Hawaii Study Area (Kratofil et al., 2023)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale.................. Reproductive....... Parent............. Main Hawaiian December through 23,041 B.1-11 2 2 2 2 Static.............. None.
Islands--Parent. May.
Humpback whale.................. Reproductive....... Child.............. Main Hawaiian December through 6,676 B.1-11 3 3 3 3 Static.............. None.
Islands--Child. May.
False killer whale.............. Small and Resident Parent............. Main Hawaiian Year-round........ 94,217 B.1-7 1 1 3 3 Static.............. None.
Population. Islands Insular
Stock--Parent.
False killer whale.............. Small and Resident Child.............. Main Hawaiian Year-round........ 7,775 B.1-7 3 3 3 3 Static.............. None.
Population. Islands Insular
Stock--Child.
False killer whale.............. Small and Resident Non-hierarchical... Northwestern Year-round........ 138,001 B.1-7 1 1 2 2 Static.............. None.
Population. Hawaiian Islands
Insular Stock.
Dwarf sperm whale............... Small and Resident Parent............. Hawaii Island-- Year-round........ 1,341 B.1-14 3 3 2 2 Static.............. None.
Population. Parent.
Dwarf sperm whale............... Small and Resident Child.............. Hawaii Island-- Year-round........ 457 B.1-14 3 3 2 2 Static.............. None.
Population. Child.
Pygmy killer whale.............. Small and Resident Non-hierarchical... O[revaps]ahu-Maui Year-round........ 7,416 B.1-15 3 3 2 2 Static.............. None.
Population. Nui.
Pygmy killer whale.............. Small and Resident Non-hierarchical... Hawaii Island..... Year-round........ 5,201 B.1-15 2 2 2 2 Static.............. None.
Population.
Short-finned pilot whale........ Small and Resident Parent............. Main Hawaiian Year-round........ 51,280 B.1-16 1 1 3 3 Static.............. None.
Population. Islands--Parent.
Short-finned pilot whale........ Small and Resident Child.............. Main Hawaiian Year-round........ 4,040 B.1-16 3 3 3 3 Static.............. None.
Population. Islands--Child
(Western
Community Core
Range).
Short-finned pilot whale........ Small and Resident Child.............. Main Hawaiian Year-round........ 2,427 B.1-16 3 3 3 3 Static.............. None.
Population. Islands--Child
(Central
Community Core
Range).
Short-finned pilot whale........ Small and Resident Child.............. Main Hawaiian Year-round........ 2,461 B.1-16 3 3 3 3 Static.............. None.
Population. Islands--Child
(Eastern
Community Core
Range).
Common bottlenose dolphin....... Small and Resident Parent............. Kaua[revaps]i/ Year-round........ 36,634 B.1-18 1 1 3 2 Static.............. None.
Population. Ni[revaps]ihau-
O[revaps]ahu-Maui
Nui.
Common bottlenose dolphin....... Small and Resident Child.............. Kaua[revaps]i/ Year-round........ 2,772 B.1-18 3 3 3 3 Static.............. None.
Population. Ni[revaps]ihau-
O[revaps]ahu-Maui
Nui-Kaua[revaps]i/
Ni[revaps]ihau).
Common bottlenose dolphin....... Small and Resident Child.............. Kaua[revaps]i/ Year-round........ 8,486 B.1-18 3 3 2 2 Static.............. None.
Population. Ni[revaps]ihau-
O[revaps]ahu-Maui
Nui--O[revaps]ahu.
Common bottlenose dolphin....... Small and Resident Child.............. Kaua[revaps]i/ Year-round........ 10,622 B.1-18 2 2 2 2 Static.............. None.
Population. Ni[revaps]ihau-
O[revaps]ahu-Maui
Nui--Maui Nui.
Common bottlenose dolphin....... Small and Resident Non-hierarchical... Hawaii Island..... Year-round........ 8,299 B.1-18 2 2 3 3 Static.............. None.
Population.

[[Page 32168]]

Pantropical spotted dolphin..... Small and Resident Parent............. O[revaps]ahu-Maui Year-round........ 57,711 B.1-19 1 1 2 2 Static.............. None.
Population. Nui-Hawaii
Island--Parent.
Pantropical spotted dolphin..... Small and Resident Child.............. O[revaps]ahu-Maui Year-round........ 12,952 B.1-19 1 1 2 2 Static.............. None.
Population. Nui-Hawaii
Island--Child
(O[revaps]ahu).
Pantropical spotted dolphin..... Small and Resident Child.............. O[revaps]ahu-Maui Year-round........ 6,743 B.1-19 1 1 2 2 Static.............. None.
Population. Nui-Hawaii
Island--Child
(Maui Nui).
Pantropical spotted dolphin..... Small and Resident Child.............. O[revaps]ahu-Maui Year-round........ 10,768 B.1-19 1 1 2 2 Static.............. None.
Population. Nui-Hawaii
Island--Hawaii
Island--Child
(Hawaii Island).
Rough-toothed dolphin........... Small and Resident Non-hierarchical... Maui Nui-Hawaii Year-round........ 15,112 B.1-21 1 1 2 2 Static.............. None.
Population. Island.
Rough-toothed dolphin........... Small and Resident Parent............. Kaua[revaps]i/ Year-round........ 24,233 B.1-21 1 1 2 2 Static.............. None.
Population. Ni[revaps]ihau-
O[revaps]ahu--Par
ent.
Rough-toothed dolphin........... Small and Resident Child.............. Kaua[revaps]i/ Year-round........ 1,149 B.1-21 2 2 2 2 Static.............. None.
Population. Ni[revaps]ihau-
O[revaps]ahu--Chi
ld (Kaua[revaps]i/
Ni[revaps]ihau).
Melon-headed whale.............. Small and Resident Non-hierarchical... Kohala Residents-- Year-round........ 3,816 B.1-21 2 2 3 3 Static.............. None.
Population. Hawaii Island.
Spinner dolphin................. Small and Resident Non-hierarchical... Manawai (Pearl and Year-round........ 2,094 B.1-20 1 2 1 2 Static.............. None.
Population. Hermes Reef).
Spinner dolphin................. Small and Resident Non-hierarchical... Kuaihelani/ Year-round........ 4,841 B.1-20 1 2 1 2 Static.............. None.
Population. H[omacr]lanik[uma
cr] (Midway/Kure
Atolls).
Spinner dolphin................. Small and Resident Non-hierarchical... Kaua[revaps]i and Year-round........ 7,233 B.1-20 1 1 2 3 Static.............. None.
Population. Ni[revaps]ihau.
Spinner dolphin................. Small and Resident Non-hierarchical... O[revaps]ahu and Year-round........ 14,651 B.1-20 1 1 2 3 Static.............. None.
Population. Maui Nui.
Spinner dolphin................. Small and Resident Non-hierarchical... Hawaii Island..... Year-round........ 9,477 B.1-20 1 1 3 3 Static.............. None.
Population.
Goose-beaked whale.............. Small and Resident Parent............. Hawaii Island..... Year-round........ 37,157 B.1-23 2 2 3 2 Static.............. None.
Population.
Goose-beaked whale.............. Small and Resident Child.............. Hawaii Island..... Year-round........ 5,400 B.1-23 3 3 3 3 Static.............. None.
Population.
Blainville's beaked whale....... Small and Resident Parent............. O[revaps]ahu-Maui Year-round........ 78,714 B.1-24 1 1 3 2 Static.............. None.
Population. Nui-Hawaii
Island--Parent.
Blainville's beaked whale....... Small and Resident Child.............. O[revaps]ahu-Maui Year-round........ 4,214 B.1-24 3 3 3 3 Static.............. None.
Population. Nui-Hawaii
Island--Child
(Hawaii Island).
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
California Study Area (Calambokidis et al., 2024)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale...................... Feeding............ Parent............. Blue whale West June through 173,433 B.1-1 2 2 3 3 Static.............. None.
Coast--Parent. November.
Blue whale...................... Feeding............ Child.............. Blue whale West June through 54,349 B.1-1 3 3 3 3 Static.............. None.
Coast--Core. November.
Fin whale....................... Feeding............ Parent............. Fin whale West June through 315,072 B.1-2 1 1 2 2 Static.............. None.
Coast--Parent. November.

[[Page 32169]]

Fin whale....................... Feeding............ Child.............. Fin whale West June through 155,508 B.1-2 2 2 2 2 Static.............. None.
Coast--Core. November.
Humpback whale.................. Feeding............ Parent............. Humpback whale March through 140,303 B.1-5 2 2 3 3 Static.............. None.
West Coast-- November.
Parent.
Humpback whale.................. Feeding............ Child.............. Humpback whale March through 38,052 B.1-5 3 3 3 3 Static.............. None.
West Coast--Core. November.
Gray whale...................... Migratory.......... Parent............. Gray Whale January through 167,066 B.1-13 1 1 2 2 Static.............. GOA.
Migratory Route-- June, November
Southbound and through December.
Northbound.
Gray whale...................... Migratory.......... Child.............. Southbound........ November-February. 70,110 B.1-13 2 2 3 3 Static.............. None.
Gray whale...................... Migratory.......... Child.............. Northbound Phase A January-May....... 65,047 B.1-13 2 2 3 3 Static.............. None.
Gray whale...................... Migratory.......... Child.............. Northbound Phase B March-May......... 51,947 B.1-13 3 3 3 3 Static.............. None.
Gray whale...................... Reproductive....... Non-hierarchical... Gray whale--Cow March-May......... 51,947 B.1-13 3 3 3 3 Static.............. None.
and Calf Migrants.
Harbor porpoise................. Small and Resident Non-hierarchical... Monterey Bay...... Year-round........ 1,911 B.1-22 2 2 3 3 Static.............. None.
Population.
Harbor porpoise................. Small and Resident Non-hierarchical... Morro Bay......... Year-round........ 3,030 B.1-22 1 1 3 3 Static.............. None.
Population.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 32170]]

National Marine Sanctuaries

Under Title III of the Marine Protection, Research, and Sanctuaries
Act of 1972 (also known as the National Marine Sanctuaries Act (NMSA)),
NOAA can establish as national marine sanctuaries (NMS) areas of the
marine environment with special conservation, recreational, ecological,
historical, cultural, archaeological, scientific, educational, or
aesthetic qualities. Sanctuary regulations prohibit destroying, causing
the loss of, or injuring any sanctuary resource managed under the law
or regulations for that sanctuary (15 CFR part 922). NMS are managed on
a site-specific basis, and each sanctuary has site-specific
regulations. Most, but not all sanctuaries have site-specific
regulatory exemptions from the prohibitions for certain military
activities. Separately, section 304(d) of the NMSA requires Federal
agencies to consult with the Office of National Marine Sanctuaries
(ONMS) whenever their Proposed Activities are likely to destroy, cause
the loss of, or injure a sanctuary resource. There are seven designated
NMSs and one proposed NMS within the HCTT Study Area (see section 6 of
the 2024 HCTT Draft EIS/OEIS):
Channel Islands NMS
Chumash Heritage NMS;
Cordell Bank NMS;
Greater Farallones NMS;
Monterey Bay NMS;
Hawaiian Islands Humpback Whale NMS
Pacific Remote Islands NMS (in designation); and
Papah[amacr]naumoku[amacr]kea NMS.
Channel Islands NMS is an ecosystem-based managed sanctuary
consisting of an area of 1,109 nmi\2\ (3,803 km\2\) around Anacapa
Island, Santa Cruz Island, Santa Rosa Island, San Miguel Island, and
Santa Barbara Island to the south. It encompasses sensitive habitats
(e.g., kelp forest habitat, deep benthic habitat) and includes various
shipwrecks and maritime heritage artifacts. Channel Islands NMS waters
and its remote, isolated position at the confluence of two major ocean
currents support significant biodiversity of marine mammals, fish, and
invertebrates. At least 33 species of cetaceans have been reported in
the Channel Islands NMS region with common species, including: Long-
beaked common dolphin, short-beaked common dolphin, Bottlenose dolphin,
Pacific white-sided dolphin, Northern right whale dolphin, Risso's
dolphin, California gray whale, Blue whale, and Humpback whale. The
three species of pinnipeds that are commonly found throughout or in
part of the Channel Islands NMS include: California sea lion, Northern
elephant seal, and Pacific harbor seal.
Chumash Heritage NMS encompasses 3,430 nmi\2\ (11,766 km\2\) of
coastal and ocean waters offshore Central California stretching nearly
52 nmi (96.6 km) from shore and down to a maximum depth of 11,580 ft
(3,530 m). The sanctuary protects and collaboratively manages natural
and cultural resources, maritime historical resources, and Indigenous
cultural history along 100 nmi (186.9 km) of coastline. Chumash
Heritage NMS contains marine biodiversity, productive ecosystems, and
sensitive species and habitats, with special geologic features like
Rodriguez Seamount and Santa Lucia Bank, along with an important
biogeographic transition zone and upwelling along the California
Current, which drives biological productivity and creates ecological
conditions in the area that supports a high abundance of marine
mammals. Different types of ecological habitats found within the
sanctuary include kelp forests, rocky reefs, deep-sea coral gardens,
and sandy beaches.
Cordell Bank NMS is an extremely productive marine area off the
West Coast in northern California, just north of the Gulf of the
Farallones. With its southern-most boundary located 36.5 nmi (67.6 km)
north of San Francisco, the sanctuary is entirely offshore, with the
eastern boundary 5.2 nmi (9.7 km) from shore and the western boundary
26.1 nmi (48.3 km) offshore. In total, the sanctuary protects an area
of 971 nmi\2\ (3,330 km\2\). The centerpiece of the sanctuary is
Cordell Bank, a 3.9 nmi by 8.3 nmi (7.2 km by 15.3 km) rocky undersea
feature. The combination of ocean conditions and undersea topography
creates a rich and diverse marine community in the sanctuary. The
prevailing California Current flows southward along the coast, and the
annual upwelling of nutrient-rich deep ocean water supports the
sanctuary's rich biological community, including marine mammals.
Greater Farallon NMS encompasses 2,488 nmi\2\ (8,534 km\2\) just
north and west of San Francisco Bay, CA, within the California Current
ecosystem. Due to a high degree of wind-driven upwelling, there is a
ready supply of nutrients to surface waters and the California Current
ecosystem is one of the most biologically productive regions in the
world. Greater Farallones NMS provides breeding and feeding grounds for
at least 25 endangered or threatened species; 36 marine mammal species,
including blue, gray, and humpback whales, harbor seals, elephant
seals, Pacific white-sided dolphins, and one of the southernmost U.S.
populations of threatened Steller sea lion.
Monterey Bay NMS is an ecosystem-based managed sanctuary consisting
of an area of 4,601 nmi\2\ (15,781 km\2\) stretching from Marin to
Cambria and extending an average of 26.1 nmi (48.3 km) from shore.
Monterey Bay NMS contains extensive kelp forests and one of North
America's largest underwater canyons and closest-to-shore deep ocean
environments. Its diverse marine ecosystem also includes rugged rocky
shores, wave-swept sandy beaches and tranquil estuaries. These habitats
support a variety of marine life, including 36 species of marine
mammals, more than 180 species of seabirds and shorebirds, at least 525
species of fishes, and an abundance of invertebrates and algae. Of the
36 species of marine mammals, six are pinnipeds with California sea
lions being the most common, and the remainder are 26 species of
cetaceans.
Hawaiian Islands Humpback Whale NMS is a single-species managed
sanctuary, composed of 1,035 nmi\2\ of the waters around Maui,
L[amacr]na[revaps]i, and Moloka[revaps]i; and smaller areas off the
north shore of Kaua[revaps]i, off Hawaii's west coast, and off the
north and southeast coasts of O[revaps]ahu. Hawaiian Islands Humpback
Whale NMS is entirely within the HRC of the HCTT Study Area and
constitutes one of the world's most important Hawaii humpback whale DPS
habitats (81 FR 62259, September 8, 2016), and is a primary region for
humpback reproduction in the U.S. (National Marine Sanctuaries Program,
2002). Scientists estimate that more than 50 percent of the entire
North Pacific humpback whale population migrates to Hawaiian waters
each winter to mate, calve, and nurse their young. The North Pacific
humpback whale population has been split into two DPSs. The Hawaii
humpback whale DPS migrates to Hawaiian waters each winter and is not
listed under the ESA. In addition to protection under the MMPA, the
Hawaii humpback whale DPS is protected in sanctuary waters by the
Hawaiian Islands Humpback Whale NMS. The sanctuary was created to
protect humpback whales and shallow, protected waters important for
calving and nursing (Office of National Marine Sanctuaries, 2010).
Papah[amacr]naumoku[amacr]kea NMS, the largest NMS, consists of
approximately 439,910 nmi\2\ (1,508,849 km\2\) of marine habitat. The
sanctuary comprises several interconnected ecosystems, such as coral
islands surrounded by shallow reefs, low-light mesophotic reefs with
extensive algal beds, open ocean waters

[[Page 32171]]

connected to the greater North Pacific Ocean, deep-water habitats such
as abyssal plains 16,400 ft (4,999 m) below sea level, and deep reef
habitat characterized by seamounts, banks, and shoals. Hawaiian monk
seals, one of the most endangered marine mammals in the world, live in
Papah[amacr]naumoku[amacr]kea NMS.
The Office of National Marine Sanctuaries is in the process of
designating the Pacific Remote Islands NMS. The atolls, shoals, banks,
reefs, seamounts, and open-ocean waters surrounding the Pacific Remote
Islands are home to some of the most diverse tropical marine life on
the planet. The region's diverse habitats and pristine reefs provide a
haven for marine mammals and numerous threatened, endangered, and
depleted species thrive in the area, including spinner dolphins and
melon-headed whales. NMFS does not anticipate injury to Sanctuary
resources in the proposed Pacific Remote Islands NMS, as the action
proponents are not proposing to conduct activities within the vicinity
of, or within, the proposed Pacific Islands Heritage NMS.

Unusual Mortality Events

An unusual mortality event (UME) is defined under Section 410(9) of
the MMPA as a stranding that is unexpected; involves a significant die-
off of any marine mammal population; and demands immediate response (16
U.S.C. 1421h(9)). From 1991 to the present, there have been 17 formally
recognized UMEs affecting marine mammals in California and Hawaii and
involving species under NMFS' jurisdiction; however, there are
currently none that are active.

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995, Wartzok and
Ketten, 1999, Au and Hastings, 2008). To reflect this, Southall et al.
(2007), Southall et al. (2019c) recommended that marine mammals be
divided into hearing groups based on directly measured (behavioral or
auditory evoked potential techniques) or estimated hearing ranges
(e.g., behavioral response data, anatomical modeling). NMFS (2024)
generalized hearing ranges were chosen based on the approximately 65-dB
threshold from the composite audiograms, previous analysis in NMFS
(2018), and/or data from Southall et al. (2007) and Southall et al.
(2019c). We note that the names of two hearing groups and the
generalized hearing ranges of all marine mammal hearing groups have
been recently updated (NMFS, 2024) as reflected below in table 16.

Table 17--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36** kHz
whales)..
High-frequency (HF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
Very High-frequency (VHF) cetaceans 200 Hz to 165 kHz.
(true porpoises, Kogia, river
dolphins, Cephalorhynchid,
Lagenorhynchus cruciger and L.
australis).
Phocid pinnipeds (PW) (underwater) 40 Hz to 90 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 68 kHz.
(sea lions and fur seals).
Phocid pinnipeds (PA) (in-air) (true 42 Hz to 52 kHz.
seals).
Otariid pinnipeds (OA) (in-air) (sea 90 Hz to 40 kHz.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on the ~65-dB threshold from composite
audiogram, previous analysis in NMFS (2018), and/or data from Southall
et al. (2007) and Southall et al. (2019). Additionally, animals are
able to detect very loud sounds above and below that ``generalized''
hearing range.
** The Action Proponents split the LF functional hearing group into LF
and VLF based on Houser et al., (2024) while NMFS Updated Technical
Guidance (NMFS, 2024) does not include these data. NMFS is aware these
data and data collected during a final field season by Houser et al.
(in prep) have implications for the generalized hearing range for low-
frequency cetaceans and their weighting function, however, as
described in the 2024 Updated Technical Guidance, it is premature for
us to propose any changes to our current Updated Technical Guidance.
Mysticete hearing data is identified as a special circumstance that
could merit reevaluating the acoustic criteria for low-frequency
cetaceans in the 2024 Updated Technical Guidance once the data from
the final field season is published. Therefore, we anticipate that
once the data are published, it will likely necessitate updating this
document (i.e., likely after the data gathered in the summer 2024
field season and associated analysis are published).

For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
The Navy adjusted these hearing groups using data from recent
hearing measurements in minke whales (Houser et al., 2024). These data
support separating mysticetes (the LF cetacean marine mammal hearing
group in table 17) into two hearing groups, which the Navy designates
as ``very low-frequency (VLF) cetaceans'' and ``low-frequency (LF)
cetaceans,'' which follows the recommendations of Southall et al.
(2019c). Within the Navy's adjusted hearing groups, the VLF cetacean
group contains the larger mysticetes (i.e., blue, fin, right, and
bowhead whales) and the LF cetacean group contains the mysticete
species not included in the VLF group (e.g., minke, humpback, gray,
pygmy right whales). Although there have been no direct measurements of
hearing sensitivity in the larger mysticetes included in Navy's VLF
hearing group, an audible frequency range of approximately 10 Hz to 30
kHz has been estimated from measured vocalization frequencies, observed
responses to playback of sounds, and anatomical analyses of the
auditory system. The upper frequency limit of hearing in Navy's LF
hearing group has been estimated in a minke whale from direct
measurements of auditory evoked potentials (Houser et al., 2024).

Potential Effects of Specified Activities on Marine Mammals and Their
Habitat

This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals section later in this document
includes a quantitative analysis of the number of individuals that are
expected to be taken

[[Page 32172]]

by this activity. The Preliminary Analysis and Negligible Impact
Determination section considers the content of this section, the
Estimated Take of Marine Mammals section, and the Proposed Mitigation
Measures section to draw conclusions regarding the likely impacts of
these activities on the reproductive success or survivorship of
individuals and whether those impacts on individuals are likely to
adversely affect the species or stock through effects on annual rates
of recruitment or survival.
The Action Proponents have requested authorization for the take of
marine mammals that may occur incidental to training and testing
activities in the HCTT Study Area. The Action Proponents analyzed
potential impacts to marine mammals from acoustic and explosive sources
and from vessel use in the application. NMFS carefully reviewed the
information provided by the Action Proponents and concurs with their
synthesis of science, along with independently reviewing applicable
scientific research and literature and other information to evaluate
the potential effects of the Action Proponents' activities on marine
mammals, which are presented in this section (see appendix D in the
2024 HCTT Draft EIS/OEIS for additional information).
Other potential impacts to marine mammals from training and testing
activities in the HCTT Study Area were analyzed in the 2024 HCTT Draft
EIS/OEIS, in consultation with NMFS as a cooperating agency, and
determined to be unlikely to result in marine mammal take. Therefore,
the Action Proponents have not requested authorization for take of
marine mammals incidental to other components of their proposed
Specified Activities, and we agree that incidental take is unlikely to
occur from those components. In this proposed rule, NMFS analyzes the
potential effects on marine mammals from the activity components that
may result in take of marine mammals: exposure to acoustic or explosive
stressors including non-impulsive (i.e., sonar and other transducers,
and vibratory pile driving) and impulsive (i.e., explosives, impact
pile driving, launches, and air guns) stressors and vessel movement.
For the purpose of MMPA incidental take authorizations, NMFS'
effects assessments serve four primary purposes: (1) to determine
whether the specified activities would have a negligible impact on the
affected species or stocks of marine mammals (based on whether it is
likely that the activities would adversely affect the species or stocks
through effects on annual rates of recruitment or survival); (2) to
determine whether the specified activities would have an unmitigable
adverse impact on the availability of the species or stocks for
subsistence uses; (3) to prescribe the permissible methods of taking
(i.e., Level B harassment (behavioral harassment and temporary
threshold shift (TTS)), Level A harassment (auditory injury (AUD INJ),
non-auditory injury), serious injury, or mortality), including
identification of the number and types of take that could occur by
harassment, serious injury, or mortality, and to prescribe other means
of effecting the least practicable adverse impact on the species or
stocks and their habitat (i.e., mitigation measures); and (4) to
prescribe requirements pertaining to monitoring and reporting.
In this section, NMFS provides a description of the ways marine
mammals may be generally affected by these activities in the form of
mortality, physical injury, sensory impairment (permanent and temporary
threshold shifts and acoustic masking), physiological responses
(particular stress responses), behavioral disturbance, or habitat
effects. Explosives and vessel strikes, which have the potential to
result in incidental take by serious injury and/or mortality, will be
discussed in more detail in the Estimated Take of Marine Mammals
section. The Estimated Take of Marine Mammals section also discusses
how the potential effects on marine mammals from non-impulsive and
impulsive sources relate to the MMPA definitions of Level A Harassment
and Level B Harassment, and quantifies those effects that do not
qualify as a take under the MMPA. The Preliminary Analysis and
Negligible Impact Determination section assesses whether the proposed
authorized take would have a negligible impact on the affected species
and stocks.

Potential Effects of Underwater Sound on Marine Mammals

The marine soundscape is composed of both ambient and anthropogenic
sounds. Ambient sound is defined as the all-encompassing sound in a
given place and is usually a composite of sound from many sources both
near and far (American National Standards Institute, 1995). The sound
level of an area is defined by the total acoustical energy being
generated by known and unknown sources, which may include physical
(e.g., waves, wind, precipitation, earthquakes, ice, atmospheric
sound), biological (e.g., sounds produced by marine mammals, fish, and
invertebrates), and anthropogenic sound (e.g., vessels, dredging,
aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al., 1995). The result is that,
depending on the source type and its intensity, sound from the
specified activities may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
Anthropogenic sounds cover a broad range of frequencies and sound
levels and can have a range of highly variable impacts on marine life,
from none or minor to potentially severe responses, depending on
received levels, duration of exposure, behavioral context, and various
other factors. The potential effects of underwater sound from active
acoustic sources can possibly result in one or more of the following:
temporary or permanent hearing impairment, other auditory injury, non-
auditory physical or physiological effects, behavioral disturbance,
stress, and masking (Richardson et al., 1995; Gordon et al., 2003;
Nowacek et al., 2007; Southall et al., 2007; G[ouml]tz et al., 2009,
Southall et al., 2019a). The degree of effect is intrinsically related
to the signal characteristics, received level, distance from the
source, and duration of the sound exposure. In general, sudden, high-
level sounds can cause auditory injury, as can longer exposures to
lower level sounds. Temporary or permanent loss of hearing can occur
after exposure to noise and occurs almost exclusively for noise within
an animal's hearing range.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur, in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First is the area within which the acoustic signal would be
audible (potentially perceived) to the animal, but not strong enough to
elicit

[[Page 32173]]

any overt behavioral or physiological response. The next zone
corresponds with the area where the signal is audible to the animal and
of sufficient intensity to elicit behavioral or physiological
responsiveness. Third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory systems. Overlaying these zones
to a certain extent is the area within which masking (i.e., when a
sound interferes with or masks the ability of an animal to detect a
signal of interest that is above the absolute hearing threshold) may
occur; the masking zone may be highly variable in size.
We also describe more severe potential effects (i.e., certain non-
auditory physical or physiological effects). Potential effects from
impulsive sound sources can range in severity from effects such as
behavioral disturbance or tactile perception to physical discomfort,
slight injury of the internal organs and the auditory system, or, in
the case of explosives, more severe injuries or mortality (Yelverton et
al., 1973). Non-auditory physiological effects or injuries that
theoretically might occur in marine mammals exposed to high levels of
underwater sound or as a secondary effect of extreme behavioral
responses (e.g., change in dive profile as a result of an avoidance
response) caused by exposure to sound include neurological effects,
bubble formation, resonance effects, and other types of organ or tissue
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack,
2007; Tal et al., 2015).
Hearing
Marine mammals have adapted hearing based on their biology and
habitat: amphibious marine mammals (e.g., pinnipeds that spend time on
land and underwater) have modified ears that allow them to hear both
in-air and in-water, while fully aquatic marine mammals (e.g.,
cetaceans that are always underwater) have specialized ear adaptations
for in-water hearing (Wartzok and Ketten, 1999). These adaptations
explain the variation in hearing ability and sensitivity among marine
mammals and have led to the characterization of marine mammal
functional hearing groups based on those sensitivities: very low-
frequency cetaceans (VLF group: blue, fin, right, and bowhead whales),
low-frequency cetaceans (LF group: minke, sei, Bryde's, Rice's,
humpback, gray, and pygmy right whales), high-frequency (HF) cetaceans
(HF group: sperm whales, beaked whales, killer whale, melon-headed
whale, false/pygmy killer whale, pilot whales, and some dolphin
species), very high-frequency (VHF) cetaceans (VHF group: some dolphin
species, porpoises, Amazon River dolphin, Kogia species, Baiji, and La
Plata dolphin), sirenians (SI) (SI group: manatees, dugongs), otariids
(OCW) and other non-phocid marine carnivores (OCA) in water and in air
(OCW and OCA groups: sea lion, fur seal, walrus, otter), and phocids in
water (PCW) and in air (PCA) (PCW and PCA groups: true seals) (Southall
et al., 2019). In Phase III, VLF and LF cetaceans were part of one,
combined LF cetacean hearing group. However, as described in the Navy's
report ``Criteria and Thresholds for U.S. Navy Acoustic and Explosive
Effects Analysis (Phase 4)'' (U.S. Department of the Navy, 2025),
hereafter referred to as the Criteria and Thresholds Technical Report,
Houser et al. (2024) recently reported obtaining hearing measurements
for minke whales, the first direct measurements for a baleen whale
species, using auditory evoked potential (AEP) methodology. The Action
Proponents incorporated these measurements, as well as Southall et al.
(2019), into their analysis. They determined that the data support
dividing mysticetes into two separate hearing groups: VLF and LF
cetaceans, and NMFS concurs, (as described further in the Estimated
Take of Marine Mammals section), that this approach is appropriate for
this action.
The hearing sensitivity of marine mammals is also directional,
meaning the angle between an animal's position and the location of a
sound source impacts the animal's hearing threshold, thereby impacting
an animal's ability to perceive the sound emanating from that source.
This directionality is likely useful for determining the general
location of a sound, whether for detection of prey, predators, or
members of the same species, and can be dependent upon the frequency of
the sound (Accomando et al., 2020; Au and Moore, 1984; Byl et al.,
2016; Byl et al. 2019; Kastelein et al., 2005; Kastelein et al., 2019;
Popov and Supin, 2009).
Acoustic Signaling
An acoustic signal refers to the sound waves used to communicate
underwater, and marine mammals use a variety of acoustic signals for
socially important functions, such as communicating, as well as
biologically important functions, such as echolocating (Richardson et
al., 1995; Wartzok and Ketten, 1999). Acoustic signals used for
communication are lower frequency (i.e., 20 Hz to 30 kHz) than those
signals used for echolocation, which are high-frequency (approximately
10-200 kHz peak frequency) signals used by odontocetes to sense their
underwater environment. Lower frequency vocalizations used for
communication may have a specific, prominent fundamental frequency
(Brady et al., 2021) or have a wide frequency range, depending on the
functional hearing group and whether the marine mammal is vocalizing
in-water or in-air. Acoustic signals used for echolocation are high-
frequency, high-energy sounds with patterns and peak frequencies that
are often species-specific (Baumann-Pickering et al., 2013).
Marine mammal species typically produce sounds at frequencies
within their own hearing range, though auditory and vocal ranges do not
perfectly align (e.g., odontocetes may only hear a portion of the
frequencies of an echolocation click). Because determining a species
vocal range is easier than determining a species' hearing range, vocal
ranges are often used to infer a species' hearing range when species-
specific hearing data are not available (e.g., large whale species).
Hearing Loss and Auditory Injury
Marine mammals, like all mammals, lose their ability to hear over
time due to age-related degeneration of auditory pathways and sensory
cells of the inner ear. This natural, age-related hearing loss is
distinct from acute noise-induced hearing loss (M[oslash]ller, 2013).
Noise-induced hearing loss can be temporary (i.e., TTS) or permanent
(permanent threshold shift (PTS)), and higher-level sound exposures are
more likely to cause PTS or other AUD INJ. For marine mammals, AUD INJ
is considered to be possible when sound exposures are sufficient to
produce 40 dB of TTS measured approximately 4 minutes after exposure
(U.S. Department of the Navy, 2025). Numerous studies have directly
examined noise-induced hearing loss in marine mammals by measuring an
animal's hearing threshold before and after exposure to intense sounds.
The difference between the post-exposure and pre-exposure hearing
thresholds is then used to determine the amount of TTS (in dB) that was
produced as a result of the sound exposure (see appendix D of the 2024
HCTT Draft EIS/OEIS for additional details). The Navy used these
studies to generate exposure functions, which are predictions of the
onset of TTS or PTS based on sound frequency, level, and type
(continuous or impulsive), for each marine mammal functional hearing
group (U.S. Department of the Navy, 2025).

[[Page 32174]]

TTS can last from minutes or hours to days (i.e., there is recovery
back to baseline/pre-exposure hearing threshold), can occur within a
specific frequency range (i.e., an animal might only have a temporary
loss of hearing sensitivity within a limited frequency band of its
auditory range), and can be of varying amounts (e.g., an animal's
hearing sensitivity might be reduced by only 6 dB or reduced by 30 dB).
While there is no simple functional relationship between TTS and PTS or
other AUD INJ (e.g., neural degeneration), as TTS increases, the
likelihood that additional exposure to increased SPL or duration will
result in PTS or other injury also increases (see appendix D of the
2024 HCTT Draft EIS/OEIS for additional discussion). Exposure
thresholds for the occurrence of AUD INJ, which include the potential
for PTS, as well as situations when AUD INJ occurs without PTS, can
therefore be defined based on a specific amount of TTS; that is,
although an exposure has been shown to produce only TTS, we assume that
any additional exposure may result in some AUD INJ. The specific upper
limit of TTS is based on experimental data showing amounts of TTS that
have not resulted in AUD INJ. In other words, we do not need to know
the exact functional relationship between TTS and AUD INJ, we only need
to know the upper limit for TTS before some AUD INJ is possible. In
severe cases of AUD INJ, there can be total or partial deafness, while
in most cases the animal has an impaired ability to hear sounds in
specific frequency ranges (Kryter, 1985).
The following physiological mechanisms are thought to play a role
in inducing auditory threshold shift: effects to sensory hair cells in
the inner ear that reduce their sensitivity; modification of the
chemical environment within the sensory cells; residual muscular
activity in the middle ear; displacement of certain inner ear
membranes; increased blood flow; and post-stimulatory reduction in both
efferent and sensory neural output (Southall et al., 2007). The
amplitude, duration, frequency, temporal pattern, and energy
distribution of sound exposure all can affect the amount of associated
threshold shift and the frequency range in which it occurs. Generally,
the amount of threshold shift, and the time needed to recover from the
effect, increase as amplitude and duration of sound exposure increases.
Human non-impulsive noise exposure guidelines are based on the
assumption that exposures of equal energy (the same SEL) produce equal
amounts of hearing impairment regardless of how the sound energy is
distributed in time (NIOSH, 1998). Previous marine mammal TTS studies
have also generally supported this equal energy relationship (Southall
et al., 2007). SEL is used to predict TTS in marine mammals and is
considered a good predictor of TTS for shorter duration exposures than
longer duration exposures. The amount of TTS increases with exposure
SPL and duration, and is correlated with SEL, but duration of the
exposure has a more significant effect on TTS than would be predicted
based on SEL alone (e.g., Finneran et al., 2010b; Kastak et al., 2007;
Kastak et al., 2005; Kastelein et al., 2014a; Mooney et al., 2009a;
Popov et al., 2014; Gransier and Kastelein, 2024). These studies
highlight the inherent complexity of predicting TTS onset in marine
mammals, as well as the importance of considering exposure duration
when assessing potential impacts.
Generally, TTS increases with SEL in a non-linear fashion, where
lower SEL exposures will elicit a steady rate of TTS increase while
higher SEL exposures will either increase TTS more rapidly or plateau
(Finneran, 2015; U.S. Department of the Navy, 2025). Additionally, with
sound exposures of equal energy, those that had lower SPL with longer
duration were found to induce TTS onset at lower levels than those of
higher SPL and shorter duration. Less threshold shift will occur from
intermittent sounds than from a continuous exposure with the same
energy (some recovery can occur between intermittent exposures) (Kryter
et al., 1966; Ward, 1997; Mooney et al., 2009a, 2009b; Finneran et al.,
2010; Kastelein et al., 2014; Kastelein et al., 2015). For example, one
short, higher SPL sound exposure may induce the same impairment as one
longer lower SPL sound, which in turn may cause more impairment than a
series of several intermittent softer sounds with the same total energy
(Ward, 1997). Additionally, though TTS is temporary, very prolonged or
repeated exposure to sound strong enough to elicit TTS, or shorter-term
exposure to sound levels well above the TTS threshold, can cause AUD
INJ, at least in terrestrial mammals (Kryter, 1985; Lonsbury-Martin et
al., 1987).
Although TTS increases non-linearly in marine mammals, recovery
from TTS typically occurs in a linear fashion with the logarithm of
time (Finneran, 2015; Finneran et al., 2010a; Finneran et al., 2010b;
Finneran and Schlundt, 2013; Kastelein et al., 2012a; Kastelein et al.,
2012b; Kastelein et al., 2013a; Kastelein et al., 2014a; Kastelein et
al., 2014b; Kastelein et al., 2014c; Popov et al., 2014; Popov et al.,
2013; Popov et al., 2011; Muslow et al., 2023; Finneran et al., 2023).
Considerable variation has been measured in individuals of the same
species in both the amount of TTS incurred from similar SELs (Kastelein
et al., 2012a; Popov et al., 2013) and the time-to-recovery from TTS
(Finneran, 2015; Kastelein et al., 2019e). Many of these studies relied
on continuous sound exposures, but intermittent, impulsive sound
exposures have also been tested. The sound resulting from an explosive
detonation is considered an impulsive sound, but no direct measurements
of hearing loss from exposure to explosive sources have been made. Few
studies (Finneran et al., 2002; Lucke et al., 2009; Sills et al., 2020;
Muslow et al., 2023) using impulsive sounds have produced enough TTS to
make predictions about hearing loss due to this source type (see U.S.
Department of the Navy, 2025). In general, predictions of TTS based on
SEL for this type of sound exposure are likely to overestimate TTS
because some recovery from TTS may occur in the quiet periods between
impulsive sounds--especially when the duty cycle is low. Peak SPL
(unweighted) is also used to predict TTS due to impulsive sounds
(Southall et al., 2007; Southall et al., 2019c; U.S. Department of the
Navy, 2025).
Specific to land-based missile and target launches (characterized
by sudden onset of sound, moderate to high peak sound levels (depending
on the type of missile and distance), and short sound duration)
although it is possible that some pinnipeds may incur TTS during
launches from SNI (TTS is not anticipated during launches from PMRF),
hearing impairment has not been measured for pinniped species exposed
to launch sounds. Auditory brainstem response (i.e., hearing assessment
using measurements of electrical responses of the brain) was used to
demonstrate that harbor seals did not exhibit loss in hearing
sensitivity following launches of large rockets at Vandenberg Space
Force Base (VSFB, formerly Vandenberg Air Force Base) (Thorson et al.,
1999; Thorson et al., 1998). However, the hearing tests did not begin
until at least 45 minutes after the launch; therefore, harbor seals may
have incurred TTS which was undetectable by the time testing began.
There was no sign of PTS in any of the harbor seals tested (Thorson et
al., 1999; Thorson et al., 1998). Since 2001, no launch events at SNI
have exposed pinnipeds to noise levels at or exceeding those where PTS
could be incurred. Of note, the range to PTS and

[[Page 32175]]

TTS would not reach haulout locations for Hawaiian monk seals on
beaches at PMRF (see section 6.3.2 of the application).
Based on measurements of received sound levels during previous
launches at SNI (Burke 2017; Holst et al., 2010; Holst et al., 2005a;
Holst et al., 2008; Holst et al., 2011; Ugoretz 2016; Ugoretz and
Greene Jr. 2012), the Navy expects that there is a very limited
potential of TTS for a few of the pinnipeds present, particularly for
phocids. Available evidence from launch monitoring at SNI in 2001-2017
suggests that only a limited number of launch events produced sound
levels that could elicit TTS for some pinnipeds (Burke 2017; Holst et
al., 2008; Holst et al., 2011; Ugoretz 2016; Ugoretz and Greene Jr.
2012). In general, if any TTS were to occur to pinnipeds, it is
expected to be mild and reversible. It is possible that some launch
sounds as measured close to the launchers may exceed the auditory
injury criteria, but it is not expected that any pinnipeds would be
close enough to the launchers to be exposed to sounds strong enough to
cause auditory injury. Due to the expected sound levels of the
activities proposed and the distance of the activity from marine mammal
habitat, the effects of sounds from the proposed activities are
unlikely to result in auditory injury.
In some cases, intense noise exposures have caused AUD INJ (e.g.,
loss of cochlear neuron synapses), despite thresholds eventually
returning to normal (i.e., it is possible to have AUD INJ without a
resulting PTS (e.g., Kujawa and Liberman, 2006, 2009; Fernandez et al.,
2015; Ryan et al., 2016; Houser, 2021)). In these situations, however,
threshold shifts were 30-50 dB measured 24 hours after the exposure
(i.e., there is no evidence that an exposure resulting in less than 40
dB TTS measured a few minutes after exposure can produce AUD INJ).
Therefore, an exposure producing 40 dB of TTS, measured a few minutes
after exposure, can also be used as an upper limit to prevent AUD INJ
(i.e., it is assumed that exposures beyond those capable of causing 40
dB of TTS have the potential to result in INJ (which may or may not
result in PTS)).
Irreparable damage to the inner or outer cochlear hair cells may
cause PTS; however, other mechanisms are also involved, such as
exceeding the elastic limits of certain tissues and membranes in the
middle and inner ears and resultant changes in the chemical composition
of the inner ear fluids (Southall et al., 2007). When AUD INJ occurs,
there is physical damage to the sound receptors in the ear, whereas TTS
represents primarily tissue fatigue and is reversible (Southall et al.,
2007). AUD INJ is permanent (i.e., there is incomplete recovery back to
baseline/pre-exposure levels) but also can occur in a specific
frequency range and amount as mentioned above for TTS. In addition,
other investigators have suggested that TTS is within the normal bounds
of physiological variability and tolerance and does not represent
physical injury (e.g., Ward, 1997). Therefore, NMFS does not consider
less than 40 dB of TTS to constitute AUD INJ. The NMFS Acoustic Updated
Technical Guidance (NMFS, 2024), which was used in the assessment of
effects for this proposed rule, compiled, interpreted, and synthesized
the best available scientific information for noise-induced hearing
effects for marine mammals to derive updated thresholds for assessing
the impacts of noise on marine mammal hearing.
While many studies have examined noise-induced hearing loss in
marine mammals (see Finneran (2015) and Southall et al. (2019a) for
summaries), published data on the onset of TTS for cetaceans are
limited to the captive bottlenose dolphin, beluga, harbor porpoise, and
Yangtze finless porpoise, and for pinnipeds in water, measurements of
TTS are limited to harbor seals, elephant seals, California sea lions,
and bearded seals. These studies examine hearing thresholds measured in
marine mammals before and after exposure to intense sounds, which can
then be used to determine the amount of threshold shift at various
post-exposure times. NMFS has reviewed the available studies, which are
summarized below (see also the 2024 HCTT Draft EIS/OEIS which includes
additional discussion on TTS studies related to sonar and other
transducers).
The method used to test hearing may affect the resulting
amount of measured TTS, with neurophysiological measures producing
larger amounts of TTS compared to psychophysical measures (Finneran et
al., 2007; Finneran, 2015).
The amount of TTS varies with the hearing test frequency.
As the exposure SPL increases, the frequency at which the maximum TTS
occurs also increases (Kastelein et al., 2014b). For high-level
exposures, the maximum TTS typically occurs one-half to one octave
above the exposure frequency (Finneran et al., 2007; Mooney et al.,
2009a; Nachtigall et al., 2004; Popov et al., 2011; Popov et al., 2013;
Schlundt et al., 2000). The overall spread of TTS from tonal exposures
can therefore extend over a large frequency range (i.e., narrowband
exposures can produce broadband (greater than one octave) TTS).
The amount of TTS increases with exposure SPL and duration
and is correlated with SEL, especially if the range of exposure
durations is relatively small (Kastak et al., 2007; Kastelein et al.,
2014b; Popov et al., 2014). As the exposure duration increases,
however, the relationship between TTS and SEL begins to break down.
Specifically, duration has a more significant effect on TTS than would
be predicted on the basis of SEL alone (Finneran et al., 2010a; Kastak
et al., 2005; Mooney et al., 2009a). This means if two exposures have
the same SEL but different durations, the exposure with the longer
duration (thus lower SPL) will tend to produce more TTS than the
exposure with the higher SPL and shorter duration. In most acoustic
impact assessments, the scenarios of interest involve shorter duration
exposures than the marine mammal experimental data from which impact
thresholds are derived; therefore, use of SEL tends to over-estimate
the amount of TTS. Despite this, SEL continues to be used in many
situations because it is relatively simple, more accurate than SPL
alone, and lends itself easily to scenarios involving multiple
exposures with different SPL (Finneran, 2015).
Gradual increases of TTS may not be directly observable
with increasing exposure levels, before the onset of PTS (Reichmuth et
al., 2019). Similarly, PTS can occur without measurable behavioral
modifications (Reichmuth et al., 2019).
The amount of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity,
are less hazardous than those at higher frequencies, near the region of
best sensitivity (Finneran and Schlundt, 2013). The onset of TTS--
defined as the exposure level necessary to produce 6 dB of TTS (i.e.,
clearly above the typical variation in threshold measurements)--also
varies with exposure frequency. At the low frequency end of a species'
hearing curve, onset-TTS exposure levels are higher compared to those
in the region of best sensitivity.
TTS can accumulate across multiple exposures, but the
resulting TTS will be less than the TTS from a single, continuous
exposure with the same SEL (Finneran et al., 2010a; Kastelein et al.,
2014b; Kastelein et al., 2015b; Mooney et al., 2009b). This means that
TTS predictions based on the total, cumulative SEL will overestimate
the amount of TTS from

[[Page 32176]]

intermittent exposures such as sonars and impulsive sources.
The amount of observed TTS tends to decrease with
increasing time following the exposure; however, the relationship is
not monotonic (i.e., increasing exposure does not always increase TTS).
The time required for complete recovery of hearing depends on the
magnitude of the initial shift; for relatively small shifts recovery
may be complete in a few minutes, while large shifts (e.g.,
approximately 40 dB) may require several days for recovery. Under many
circumstances TTS recovers linearly with the logarithm of time
(Finneran et al., 2010a, 2010b; Finneran and Schlundt, 2013; Kastelein
et al., 2012a; Kastelein et al., 2012b; Kastelein et al., 2013a;
Kastelein et al., 2014b; Kastelein et al., 2014c; Popov et al., 2011;
Popov et al., 2013; Popov et al., 2014). This means that for each
doubling of recovery time, the amount of TTS will decrease by the same
amount (e.g., 6 dB recovery per doubling of time).
Nachtigall et al. (2018) and Finneran (2018) describe the
measurements of hearing sensitivity of multiple odontocete species
(i.e., bottlenose dolphin, harbor porpoise, beluga, and false killer
whale) when a relatively loud sound was preceded by a warning sound.
These captive animals were shown to reduce hearing sensitivity when
warned of an impending intense sound. Based on these experimental
observations of captive animals, the authors suggest that wild animals
may dampen their hearing during prolonged exposures or if conditioned
to anticipate intense sounds. Finneran (2018) recommends further
investigation of the mechanisms of hearing sensitivity reduction in
order to understand the implications for interpretation of existing TTS
data obtained from captive animals, notably for considering TTS due to
short duration, unpredictable exposures.
Marine mammal hearing plays a critical role in communication with
conspecifics and in interpretation of environmental cues for purposes
such as predator avoidance and prey capture. Depending on the degree
(elevation of threshold in dB), duration (i.e., recovery time), and
frequency range of TTS, and the context in which it is experienced, TTS
can have effects on marine mammals ranging from discountable to serious
similar to those discussed in auditory masking, below. For example, a
marine mammal may be able to readily compensate for a brief, relatively
small amount of TTS in a non-critical frequency range that takes place
during a time where ambient noise is lower and there are not as many
competing sounds present. Alternatively, a larger amount and longer
duration of TTS sustained during a time when communication is critical
for successful mother/calf interactions could have more serious impacts
if it were in the same frequency band as the necessary vocalizations
and of a severity that impeded communication. The fact that animals
exposed to high levels of sound that would be expected to result in
this physiological response would also be expected to have behavioral
responses of a comparatively more severe or sustained nature is
potentially more significant than the simple existence of a TTS.
However, it is important to note that TTS could occur due to longer
exposures to sound at lower levels so that a behavioral response may
not be elicited.
Depending on the degree and frequency range, the effects of AUD INJ
on an animal could also range in severity, although it is considered
generally more serious than TTS because it is a permanent condition
(Reichmuth et al., 2019). Of note, reduced hearing sensitivity as a
simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without some cost to the animal.
As the amount of research on hearing sensitivity has grown, so,
too, has the understanding that marine mammals may be able to self-
mitigate, or protect, against noise-induced hearing loss. An animal may
learn to reduce or suppress their hearing sensitivity when warned of an
impending intense sound exposure, or if the duty cycle of the sound
source is predictable (Finneran, 2018; Finneran et al., 2024;
Nachtigall and Supin, 2013, 2014, 2015; Nachtigall et al., 2016a,
2016b, 2016c, 2018). This has been shown with several species,
including the false killer whale (Nachtigall and Supin, 2013),
bottlenose dolphin (Finneran, 2018; Nachtigall and Supin, 2014, 2015;
Nachtigall et al., 2016c), beluga whale (Nachtigall et al., 2016a), and
harbor porpoise (Nachtigall et al., 2016b). Additionally, Finneran et
al. (2023) and Finneran et al. (2024) found that odontocetes that had
participated in TTS experiments in the past could have learned from
that experience and subsequently protected their hearing during new
sound exposure experiments.

Behavioral Responses

Behavioral responses to sound are highly variable and context-
specific (Nowacek et al., 2007; Southall et al., 2007; Southall et al.,
2019). Many different variables can influence an animal's perception of
and response to (nature and magnitude) an acoustic event. An animal's
prior experience with a sound or sound source affects whether it is
less likely (habituation, self-mitigation) or more likely
(sensitization) to respond to certain sounds in the future (animals can
also be innately predisposed to respond to certain sounds in certain
ways) (Southall et al., 2007; Southall et al., 2016; Finneran, 2018;
Finneran et al., 2024; Nachtigall and Supin, 2013, 2014, 2015;
Nachtigall et al., 2015; Nachtigall et al., 2016a, 2018; Nachtigall et
al., 2016b). Related to the sound itself, the perceived proximity of
the sound, bearing of the sound (approaching vs. retreating), the
similarity of a sound to biologically relevant sounds in the animal's
environment (i.e., calls of predators, prey, or conspecifics),
familiarity of the sound, and navigational constraints may affect the
way an animal responds to the sound (Ellison et al., 2012; Southall et
al., 2007, DeRuiter et al., 2013a, Southall et al., 2021; Wartzok et
al., 2003). Individuals (of different age, gender, reproductive status,
etc.) among most populations will have variable hearing capabilities,
and differing behavioral sensitivities to sounds that will be affected
by prior conditioning, experience, and current activities of those
individuals. Southall et al. (2007) and Southall et al. (2021) have
developed and subsequently refined methods developed to categorize and
assess the severity of acute behavioral responses, considering impacts
to individuals that may consequently impact populations. Often,
specific acoustic features of the sound and contextual variables (i.e.,
proximity, duration, or recurrence of the sound or the current behavior
that the marine mammal is engaged in or its prior experience), as well
as entirely separate factors such as the physical presence of a nearby
vessel, may be more relevant to the animal's response than the received
level alone.
Studies by DeRuiter et al. (2013a) indicate that variability of
responses to acoustic stimuli depends not only on the species receiving
the sound and the sound source, but also on the social, behavioral, or
environmental contexts of exposure. Another study by DeRuiter et al.
(2013b) examined behavioral responses of goose-beaked whales to MF
sonar and found that whales responded strongly at low received levels
(89-127 dB re 1 [micro]Pa) by ceasing normal fluking

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and echolocation, swimming rapidly away, and extending both dive
duration and subsequent non-foraging intervals when the sound source
was 2.1-5.9 mi (3.4-9.5 km) away. Importantly, this study also showed
that whales exposed to a similar range of received levels (78-106 dB
re: 1 [micro]Pa) from distant sonar exercises 73.3 mi (118 km away) did
not elicit such responses, suggesting that context may moderate
responses.
Ellison et al. (2012) outlined an approach to assessing the effects
of sound on marine mammals that incorporates contextual-based factors.
The authors recommend considering not just the received level of sound,
but also the activity the animal is engaged in at the time the sound is
received, the nature and novelty of the sound (i.e., whether this a new
sound from the animal's perspective), and the distance between the
sound source and the animal. They submit that this ``exposure
context,'' as described, greatly influences the type of behavioral
response exhibited by the animal. Forney et al. (2017) also point out
that an apparent lack of response (e.g., no displacement or avoidance
of a sound source) may not necessarily mean there is no cost to the
individual or population, as some resources or habitats may be of such
high value that animals may choose to stay, even when experiencing
stress or hearing loss. Forney et al. (2017) recommend considering both
the costs of remaining in an area of noise exposure such as TTS, PTS,
or masking, which could lead to an increased risk of predation or other
threats or a decreased capability to forage, and the costs of
displacement, including potential increased risk of vessel strike,
increased risks of predation or competition for resources, or decreased
habitat suitable for foraging, resting, or socializing. This sort of
contextual information is challenging to predict with accuracy for
ongoing activities that occur over large spatial and temporal expanses.
However, distance is one contextual factor for which data exist to
quantitatively inform a take estimate, and the method for predicting
Level B harassment in this proposed rule does consider distance to the
source. Other factors are often considered qualitatively in the
analysis of the likely consequences of sound exposure, where supporting
information is available.
Friedlaender et al. (2016) provided the first integration of direct
measures of prey distribution and density variables incorporated into
across-individual analyses of behavior responses of blue whales to
sonar, and demonstrated a five-fold increase in the ability to quantify
variability in blue whale diving behavior. These results illustrate
that responses evaluated without such measurements for foraging animals
may be misleading, which again illustrates the context-dependent nature
of the probability of response.
Exposure of marine mammals to sound sources can result in, but is
not limited to, no response or any of the following observable
responses: increased alertness; orientation or attraction to a sound
source; vocal modifications; cessation of feeding; cessation of social
interaction; alteration of movement or diving behavior; habitat
abandonment (temporary or permanent); and, in severe cases, panic,
flight, stampede, or stranding, potentially resulting in death
(Southall et al., 2007). A review of marine mammal responses to
anthropogenic sound was first conducted by Richardson (1995). More
recent reviews (Nowacek et al., 2007; DeRuiter et al., 2013a and 2013b;
Ellison et al., 2012; Gomez et al., 2016) address studies conducted
since 1995 and focused on observations where the received sound level
of the exposed marine mammal(s) was known or could be estimated. Gomez
et al. (2016) conducted a review of the literature considering the
contextual information of exposure in addition to received level and
found that higher received levels were not always associated with more
severe behavioral responses and vice versa. Southall et al. (2016)
states that results demonstrate that some individuals of different
species display clear yet varied responses, some of which have negative
implications, while others appear to tolerate high levels, and that
responses may not be fully predictable with simple acoustic exposure
metrics (e.g., received sound level). Rather, the authors state that
differences among species and individuals along with contextual aspects
of exposure (e.g., behavioral state) appear to affect response
probability (Southall et al., 2019). The following parts provide
examples of behavioral responses to stressors that provide an idea of
the variability in responses that would be expected given the
differential sensitivities of marine mammal species to sound and the
wide range of potential acoustic sources to which a marine mammal may
be exposed. Behavioral responses that could occur for a given sound
exposure should be determined from the literature that is available for
each species (see section D.4.5 (Behavioral Reactions) of the 2024 HCTT
Draft EIS/OEIS for a comprehensive list of behavioral studies and
species-specific findings) or extrapolated from closely related species
when no information exists, along with contextual factors.
Responses Due to Sonar and Other Transducers--
Mysticetes responses to sonar and other duty-cycled tonal sounds
are dependent upon the characteristics of the signal, behavioral state
of the animal, sensitivity and previous experience of an individual,
and other contextual factors including distance of the source, movement
of the source, physical presence of vessels, time of year, and
geographic location (Goldbogen et al., 2013; Harris et al., 2019a;
Harris et al., 2015; Martin et al., 2015; Sivle et al., 2015b). For
example, a behavioral response study (BRS) in Southern California
demonstrated that individual behavioral state was critically important
in determining response of blue whales to Navy sonar. In this BRS, some
blue whales engaged in deep (greater than 164 ft (50 m)) feeding
behavior had greater dive responses than those in shallow feeding or
non-feeding conditions, while some blue whales that were engaged in
shallow feeding behavior demonstrated no clear changes in diving or
movement even when received levels were high (approximately 160 dB re 1
[micro]Pa) from exposures to 3-4 kHz sonar signals, while others showed
a clear response at exposures at lower received level of sonar and
pseudorandom noise (Goldbogen et al., 2013). Generally, behavioral
responses were brief and of low to moderate severity, and the whales
returned to baseline behavior shortly after the end of the acoustic
exposure (DeRuiter et al., 2017; Goldbogen et al., 2013; Southall et
al., 2019c). To better understand the context of these behavioral
responses, Friedlaender et al. (2016) mapped the prey field of the
deep-diving blue whales and found that the response to sound was more
apparent for individuals engaged in feeding than those that were not.
The probability of a moderate behavioral response increased when the
source was closer for these foraging blue whales, although there was a
high degree of uncertainty in that relationship (Southall et al.,
2019b). In the same BRS, none of the tagged fin whales demonstrated
more than a brief or minor response regardless of their behavioral
state (Harris et al., 2019a). The fin whales were exposed to both mid-
frequency simulated sonar and pseudorandom noise of similar frequency,
duration, and source level. They were less sensitive to disturbance
than blue whales, with no significant differences

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in response between behavioral states or signal types. The authors
rated responses as low-to-moderate severity with no negative impact to
foraging success (Southall et al., 2023).
Similarly, while the rates of foraging lunges decrease in humpback
whales due to sonar exposure, there was variability in the response
across individuals, with one animal ceasing to forage completely and
another animal starting to forage during the exposure (Sivle et al.,
2016). In addition, almost half of the animals that exhibited avoidance
behavior were foraging before the exposure, but the others were not;
the animals that exhibited avoidance behavior while not feeding
responded at a slightly lower received level and greater distance than
those that were feeding (Wensveen et al., 2017). These findings
indicate that the behavioral state of the animal plays a role in the
type and severity of a behavioral response. Henderson et al. (2019)
examined tagged humpback whale dive and movement behavior, including
individuals incidentally exposed to Navy sonar during training
activities, at the PMRF off Kaua[revaps]i, Hawaii. Tracking data showed
that, regardless of exposure to sonar, individual humpbacks spent
limited time, no more than a few days, in the vicinity of
Kaua[revaps]i. Potential behavioral responses due to sonar exposure
were limited and may have been influenced by breeding and social
behaviors. Martin et al. (2015) found that the density of calling minke
whales was reduced during periods of Navy training involving sonar
relative to the periods before training began and increased again in
the days following the completion of training activities. The responses
of individual whales could not be assessed, so in this case it is
unknown whether the decrease in calling animals indicated that the
animals left the range or simply ceased calling. Harris et al. (2019b)
utilized acoustically generated minke whale tracks to statistically
demonstrate changes in the spatial distribution of minke whale acoustic
presence before, during, and after surface ship MFAS training. The
spatial distribution of probability of acoustic presence was different
in the ``during'' phase compared to the ``before'' phase, and the
probability of presence at the center of ship activity during MFAS
training was close to zero for both years. The ``after'' phases for
both years retained lower probabilities of presence suggesting the
return to baseline conditions may take more than five days. The results
show a clear spatial redistribution of calling minke whales during
surface ship MFAS training, however a limitation of passive acoustic
monitoring is that one cannot conclude if the whales moved away, went
silent, or a combination of the two.
Building on this work, Durbach et al. (2021) used the same data and
determined that individual minke whales tended to be in either a fast
or slow movement behavior state while on the missile range, where
whales tended to be in the slow state in baseline or before periods but
transitioned into the fast state with more directed movement during
sonar exposures. They also moved away from the area of sonar activity
on the range, either to the north or east depending on where the
activity was located; this explains the spatial redistribution found by
Harris et al. (2019b). Minke whales were also more likely to stop
calling when in the fast state, regardless of sonar activity, or when
in the slow state during sonar activity (Durbach et al., 2021).
Similarly, minke whale detections were reduced or ceased altogether
during periods of sonar use off Jacksonville, Florida, (Norris et al.,
2012; Simeone et al., 2015; U.S. Department of the Navy, 2013),
especially with an increased ping rate (Charif et al., 2015).
Odontocetes have varied, context-dependent behavioral responses to
sonar and other transducers. Much of the research on odontocetes has
been focused on understanding the impacts of sonar and other
transducers on beaked whales because they were hypothesized to be more
susceptible to behavioral disturbance after several strandings of
beaked whales in which military MFAS was identified as a contributing
factor (see Stranding and Mortality section). Subsequent BRSs have
shown that beaked whales are likely more sensitive to disturbance than
most other cetaceans. Many species of odontocetes have been studied
during BRSs, including Blainville's beaked whale, goose-beaked whale,
Baird's beaked whale, northern bottlenose whale, harbor porpoise, pilot
whale, killer whale, sperm whale, false killer whale, melon-headed
whale, bottlenose dolphin, rough-toothed dolphin, Risso's dolphin,
Pacific white-sided dolphin, and Commerson's dolphin. Observed
responses by Blainville's beaked whales, goose-beaked whales, Baird's
beaked whales, and northern bottlenose whales (the largest of the
beaked whales), to mid-frequency sonar sounds include cessation of
clicking, decline in group vocal periods, termination of foraging
dives, changes in direction to avoid the sound source, slower ascent
rates to the surface, longer deep and shallow dive durations, and other
unusual dive behaviors (DeRuiter et al., 2013b; Hewitt et al., 2022;
Jacobson et al., 2022; McCarthy et al., 2011; Miller et al., 2015;
Moretti et al., 2014; Southall et al., 2011; Stimpert et al., 2014;
Tyack et al., 2011).
During a BRS in Southern California, a tagged Baird's beaked whale
exposed to simulated MFA sonar within 3 km increased swim speed and
modified its dive behavior (Stimpert et al., 2014). One goose-beaked
whale was also incidentally exposed to real Navy sonar located over
62.1 mi (100 km) away in addition to the source used in the controlled
exposure study, and the authors did not detect similar responses at
comparable received levels. Received levels from the MFA sonar signals
from the controlled (2.1 to 5.9 mi (3.4 to 9.5 km)) exposures were
calculated as 84-144 dB re 1 [mu]Pa, and incidental (73.3 mi (118 km))
exposures were calculated as 78-106 dB re 1 [mu]Pa, indicating that
context of the exposures (e.g., source proximity, controlled source
ramp-up) may have been a significant factor in the responses to the
simulated sonars (DeRuiter et al., 2013b).
Long-term tagging work during the same BRS demonstrated that the
longer duration dives considered a behavioral response by DeRuiter et
al. (2013b) fell within the normal range of dive durations found for
eight tagged goose-beaked whales on the Southern California Offshore
Range (Schorr et al., 2014). However, the longer inter-deep dive
intervals found by DeRuiter et al. (2013b), which were among the
longest found by Schorr et al. (2014) and Falcone et al. (2017), may
indicate a response to sonar. Williams et al. (2017) note that during
normal deep dives or during fast swim speeds, beaked whales and other
marine mammals use strategies to reduce their stroke rates (e.g.,
leaping, wave surfing when swimming, interspersing glides between bouts
of stroking when diving). The authors determined that in the post-
exposure dives by the tagged goose-beaked whales described in DeRuiter
et al. (2013b), the whales ceased gliding and swam with almost
continuous strokes. This change in swim behavior was calculated to
increase metabolic costs by about 30.5 percent and increase the amount
of energy expending on fast swim speeds from 27-59 percent of their
overall energy budget. This repartitioning of energy was detected in
the model up to 1.7 hours after the single sonar exposure. Therefore,
while the overall post-exposure dive durations were similar, the
metabolic energy calculated by Williams et al. (2017) was higher.
However, Southall et al. (2019a) found that prey availability was
higher

[[Page 32179]]

in the western area of the Southern California Offshore Range where
goose-beaked whales preferentially occurred, while prey resources were
lower in the eastern area and moderate in the area just north of the
Range. This high prey availability may indicate that goose-beaked
whales need fewer foraging dives to meet energy requirements than would
be needed in another area with fewer resources.
During a BRS in Norway, northern bottlenose whales avoided a sonar
sound source over a wide range of distances (0.5 to 17.4 mi (0.8 to 28
km)) and estimated avoidance thresholds ranging from received SPLs of
117 to 126 dB re 1 [mu]Pa. The behavioral response characteristics and
avoidance thresholds were comparable to those previously observed in
beaked whale studies; however, researchers did not observe an effect of
distance on behavioral response and found that onset and intensity of
behavioral response were better predicted by received SPL. There was
one instance where an individual northern bottlenose whale approached
the vessel, circled the sound source (source level was only 122 dB re 1
[mu]Pa), and resumed foraging after the exposure. Conversely, one
northern bottlenose whale exposed to a sonar source was documented
performing the longest and deepest dive on record for the species, and
continued swimming away from the source for more than 7 hours (Miller
et al., 2015; Siegal et al., 2022; Wensveen et al., 2019).
Research on Blainville's beaked whales at the Atlantic Undersea
Test and Evaluation Center (AUTEC) range has shown that individuals
move off-range during sonar use, only returning after the cessation of
sonar transmission (Boyd et al., 2009; Henderson et al., 2015;
Jones[hyphen]Todd et al., 2021; Manzano-Roth et al., 2022; Manzano-Roth
et al., 2016; McCarthy et al., 2011; Tyack et al., 2011). Five
Blainville's beaked whales estimated to be within 1.2 to 18 mi (2 to 29
km) of the AUTEC range at the onset of active sonar were displaced a
maximum of 17.4 to 42.3 mi (28 to 68 km) after moving away from the
range, although one individual did approach the range during active
sonar use. Researchers found a decline in deep dives at the onset of
the training and an increase in time spent on foraging dives as whales
moved away from the range. Predicted received levels at which presumed
responses were observed were comparable to those previously observed in
beaked whale studies. Acoustic data indicated that vocal periods were
detected on the range within 72 hours after training ended (Joyce et
al., 2019). However, Blainville's beaked whales have been documented to
remain on-range to forage throughout the year (Henderson et al., 2016),
indicating the AUTEC range may be a preferred foraging habitat
regardless of the effects of active sonar noise, or it could be that
there are no long-term consequences of the sonar activity. In the SOCAL
Range Complex, researchers conducting photo-identification studies have
identified approximately 100 individual goose-beaked whales, with 40
percent having been seen in one or more prior years, with re-sightings
up to 7 years apart, indicating a possible on-range resident population
(Falcone and Schorr, 2014; Falcone et al., 2009).
The probability of Blainville's beaked whale group vocal periods on
the PMRF were modeled during periods of (1) no naval activity, (2)
naval activity without hull-mounted MFA sonar, and (3) naval activity
with hull-mounted MFA sonar (Jacobson et al., 2022). At a received
level of 150 dB re 1 [mu]Pa RMS, the probability of detecting a group
vocal period during MFA sonar use decreased by 77 percent compared to
periods when general training activity was ongoing, and by 87 percent
compared to baseline (no naval activity) conditions. Jacobsen et al
(2022) found a greater reduction in probability of a group vocal period
with MFA sonar than observed in a prior study of the same species at
the AUTEC range (Moretti et al., 2014), which may be due to the
baseline period in the AUTEC study including naval activity without MFA
sonar, potentially lowering the baseline group vocal period activity in
that study, or due to differences in the residency of the populations
at each range.
Stanistreet et al. (2022) used passive acoustic recordings during a
multinational navy activity to assess marine mammal acoustic presence
and behavioral response to especially long bouts of sonar lasting up to
13 consecutive hours, occurring repeatedly over 8 days (median and
maximum SPL = 120 dB and 164 dB). Goose-beaked whales and sperm whales
substantially reduced how often they produced clicks during sonar,
indicating a decrease or cessation in foraging behavior. Few previous
studies have shown sustained changes in foraging or displacement of
sperm whales, but there was an absence of sperm whale clicks for 6
consecutive days of sonar activity. Sperm whales returned to baseline
levels of clicks within days after the activity, but beaked whale
detection rates remained low even 7 days after the exercise. In
addition, there were no detections from a Mesoplodon beaked whale
species within the area during, and at least 7 days after, the sonar
activity. Clicks from northern bottlenose whales and Sowerby's beaked
whales were also detected but were not frequent enough at the recording
site used to compare clicks between baseline and sonar conditions.
Goose-beaked whale behavioral responses (i.e., deep and shallow
dive durations, surface interval durations, inter-deep dive intervals)
on the Southern California Anti-Submarine Warfare Range were modeled
against predictor values that included helicopter dipping sonar, mid-
power MFA sonar and hull-mounted, high-power MFA sonar along with other
non-MFA sonar predictors (Falcone et al., 2017). Falcone et al. (2017)
found both shallow and deep dive durations increased as the proximity
to both mid- and high-powered sources decreased and found that surface
intervals and inter-deep dive intervals increased in the presence of
both types of sonars (helicopter dipping and hull-mounted), although
surface intervals shortened during periods without MFA sonar. Proximity
of source and receiver were important considerations, as the responses
to the mid-power MFA sonar at closer ranges were comparable to the
responses to the higher source level vessel sonar, as was the context
of the exposure. Helicopter dipping sonars are shorter duration and
randomly located, therefore more difficult to predict or track by
beaked whales and potentially more likely to elicit a response,
especially at closer distances (3.7 to 15.5 mi (6 to 25 km)) (Falcone
et al., 2017).
Sea floor depths and quantity of light (i.e., lunar cycle) are also
important variables to consider in BRSs, as goose-beaked whale foraging
dive depth increased with sea floor depth (maximum 6,561.7 ft (2,000
m)) and the amount of time spent at foraging depths (and likely
foraging) was greater at night (likely avoiding predation by staying
deeper during periods of bright lunar illumination), although they
spent more time near the surface during the night, as well,
particularly on dark nights with little moonlight, (Barlow et al.,
2020). Sonar occurred during 10 percent of the dives studied and had
little effect on the resulting dive metrics. Watwood et al. (2017)
found that the longer the duration of a sonar event, the greater
reduction in detected goose-beaked whale group dives and, as helicopter
dipping events occurred more frequently but with shorter durations than
periods of hull-mounted sonar, when looking at the number of detected
group dives there was a greater reduction during periods of hull-
mounted sonar than during helicopter

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dipping sonar. DiMarzio et al. (2019) also found that group vocal
periods (i.e., clusters of foraging pulses), on average, decreased
during sonar events on the Southern California Anti-Submarine Warfare
Range, though the decline from before the event to during the event was
significantly less for helicopter dipping events than hull-mounted
events, and there was no difference in the magnitude of the decline
between vessel-only events and events with both vessels and
helicopters. Manzano-Roth et al. (2022) analyzed long-term passive
acoustic monitoring data from the PMRF in Kaua[revaps]i, Hawaii, and
found beaked whales reduced group vocal periods during submarine
command course events and remained low for a minimum of 3 days after
the MFA sonar activity.
Harbor porpoise behavioral responses have been researched
extensively using acoustic deterrent and acoustic harassment devices;
however, BRSs using sonar are limited. Kastelein et al. (2018b) found
harbor porpoises did not respond to low-duty cycle mid-frequency sonar
tones (3.5-4.1 kHz at 2.7 percent duty cycle; e.g., one tone per
minute) at any received level, but one individual did respond (i.e.,
increased jumping, increased respiration rates) to high-duty cycle
sonar tones (3.5-4.1 kHz at 96 percent duty cycle; e.g., continuous
tone for almost a minute).
Behavioral responses by odontocetes (other than beaked whales and
harbor porpoises) to sonar and other transducers include horizontal
avoidance, reduced breathing rates, changes in behavioral state,
changes in dive behavior (Antunes et al., 2014; Isojunno et al., 2018;
Isojunno et al., 2017; Isojunno et al., 2020; Miller, 2012; Miller et
al., 2011; Miller et al., 2014; Southall et al., 2024), and, in one
study, separation of a killer whale calf from its group (Miller et al.,
2011). Some species of dolphin (e.g., bottlenose, spotted, spinner,
Clymene, Pacific white-sided, rough-toothed) are frequently documented
bowriding with vessels and the drive to engage in bowriding, whether
for pleasure or energetic savings (Fiori et al., 2024) may supersede
the impact of associated sonar noise (W[uuml]rsig et al., 1998).
In controlled exposure experiments on captive odontocetes, Houser
et al. (2013a) recorded behavioral responses from bottlenose dolphins
with 3 kHz sonar-like tones between 115-185 dB re 1 [mu]Pa, and
individuals across 10 trials demonstrated a 50 percent probability of
response at 172 dB re 1 [mu]Pa. Multiple studies have been conducted on
bottlenose dolphins and beluga whales to measure TTS (Finneran et al.,
2003a; Finneran et al., 2001; Finneran et al., 2005; Finneran and
Schlundt, 2004; Schlundt et al., 2000). During these studies, when
individuals were presented with 1-second tones up to 203 dB re 1
[mu]Pa, responses included changes in respiration rate, fluke slaps,
and a refusal to participate or return to the location of the sound
stimulus, including what appeared to be deliberate attempts by animals
to avoid a sound exposure or to avoid the location of the exposure site
during subsequent tests (Finneran et al., 2002; Schlundt et al., 2000).
Bottlenose dolphins exposed to more intense 1-second tones exhibited
short-term changes in behavior above received levels of 178-193 dB re 1
[mu]Pa, and beluga whales did so at received levels of 180-196 dB re 1
[mu]Pa and above.
While several opportunistic observations of odontocete (other than
beaked whales and harbor porpoises) responses have been recorded during
previous Navy activities and BRSs that employed sonar and sonar-like
sources, it is difficult to definitively attribute responses of non-
focal species to sonar exposure. Responses range from no response to
potential highlight-impactful responses, such as the separation of a
killer whale calf from its group (Miller et al., 2011). This may be
due, in part, to the variety of species and sensitivities of the
odontocete taxonomic group, as well as the breadth of study types
conducted and field observations, leading to the assessment of both
contextually driven and dose-based responses. The available data
indicate exposures to sonar in close proximity and with multiple
vessels approaching an animal likely lead to higher-level responses by
most odontocete species, regardless of received level or behavioral
state. However, when sources are further away and moving in variable
directions, behavioral responses are likely driven by behavioral state,
individual experience, or species-level sensitivities, as well as
exposure duration and received level, with the likelihood of response
increasing with increased received levels. As such, it is expected
odontocete behavioral responses to sonar and other transducers will
vary by species, populations, and individuals, and long-term
consequences or population-level effects are likely dependent upon the
frequency and duration of the exposure and resulting behavioral
response.
Pinniped behavioral response to sonar and other transducers is
context-dependent (e.g., Hastie et al., 2014; Southall et al., 2019).
All studies on pinniped response to sonar thus far have been limited to
captive animals, though, based on exposures of wild pinnipeds to vessel
noise and impulsive sounds (see Responses Due to Vessel Noise section
and Responses Due to Impulsive Noise section below), pinnipeds may only
respond strongly to military sonar that is in close proximity or
approaching an animal. Kvadsheim et al. (2010b) found that captive
hooded seals exhibited avoidance response to sonar signals between 1-7
kHz (160 to 170 dB re 1 [mu]Pa RMS) by reducing diving activity, rapid
surface swimming away from the source, and eventually moving to areas
of least SPL. However, the authors noted a rapid adaptation in behavior
(passive surface floating) during the second and subsequent exposures,
indicating a level of habituation within a short amount of time.
Kastelein et al. (2015c) exposed captive harbor seals to three
different sonar signals at 25 kHz with variable waveform
characteristics and duty cycles and found individuals responded to a
frequency modulated signal at received levels over 137 dB re 1 [mu]Pa
by hauling out more, swimming faster, and raising their heads or
jumping out of the water. However, seals did not respond to a
continuous wave or combination signals at any received level (up to 156
dB re 1 [mu]Pa). Houser et al. (2013a) conducted a study to determine
behavioral responses of captive California sea lions to MFA sonar at
various received levels (125 to 185 dB re 1 [mu]Pa). They found younger
animals (less than 2 years old) were more likely to respond than older
animals and responses included increased respiration rate, increased
time spent submerged, refusal to participate in a repetitive task, and
hauling out. Most responses below 155 dB re 1 [mu]Pa were changes in
respiration, while more severe responses (i.e., refusing to
participate, hauling out) began to occur over 170 dB re 1 [mu]Pa, and
many of the most severe responses came from the young sea lions.
Responses Due to Impulsive Noise--
Impulsive signals have a rapid rise time and higher instantaneous
peak pressure than other signal types, particularly at close range,
which means they are more likely to cause startle or avoidance
responses. At long distances, however, the rise time increases as the
signal duration lengthens (similar to a ``ringing'' sound), making the
impulsive signal more similar to a non-impulsive signal (Hastie et al.,
2019; Martin et al., 2020). Behavioral responses from explosive sounds
are likely to be similar to responses studied for other impulsive
noise, such as those produced by air

[[Page 32181]]

guns and impact pile driving. Data on behavioral responses to impulsive
sound sources are limited across all marine mammal groups, with only a
few studies available for mysticetes and odontocetes.
Mysticetes have varied responses to impulsive sound sources,
including avoidance, aggressive directed movement towards the source,
reduced surface intervals, altered swimming behavior, and changes in
vocalization rates (Gordon et al., 2003; McCauley et al., 2000a;
Richardson et al., 1985; Southall et al., 2007). Studies have been
conducted on many baleen whale species, including gray, humpback, blue,
fin, and bowhead whales; it is assumed that these responses are
representative of all baleen whale species. The behavioral state of the
whale seems to be an integral part of whether the animal responds and
how they respond, as does the location and movement of the sound
source, more than the received level of the sound.
If an individual is engaged in migratory behavior, it may be more
likely to respond to impulsive noise, and some species may be more
sensitive than others. Migrating gray whales showed avoidance responses
to seismic vessels at received levels between 164 and 190 dB re 1
[mu]Pa (Malme et al., 1986, Malme et al., 1988). In one study, McCauley
et al. (1998) found that migrating humpback whales in Australia showed
avoidance behavior at ranges of 3.1-5 mi (5-8 km) from a seismic array
during observational studies and controlled exposure experiments, and
another study found humpback whales in Australia decreased their dive
times and reduced their swimming speeds (Dunlop et al., 2015). However,
when comparing received levels and behavioral responses between air gun
ramp-up versus constant noise level of air guns, humpback whales did
not change their dive behavior but did deviate from their predicted
heading and decreased their swim speeds, deviating more during the
constant noise source trials but reducing swim speeds more during ramp-
up trials (Dunlop et al., 2016). In both cases, there was no dose-
response relationship with the received level of the air gun noise, and
similar responses were observed in control trials without air guns
(vessel movement remained constant across trials), so some responses
may have been due to vessel presence and not received level from the
air guns. Social interactions between males and mother-calf pairs were
reduced in the presence of vessels towing seismic air gun arrays,
regardless of whether the air guns were active or not; which indicates
that it was likely the presence of vessels (rather than the impulsive
noise generated from active air guns) that affected humpback whale
behavior (Dunlop et al., 2020).
Proximity of the impulsive source is another important factor to
consider when assessing the potential for behavioral responses in
marine mammals. Dunlop et al. (2017) found that groups of humpback
whales were more likely to avoid a smaller air gun array at closer
proximity than a larger air gun array, despite the same received level,
showing the difference in response between arrays has more to do with
the combined effects of received level and source proximity. In this
study, responses were varied and generally small, with short-term
course deviations of about 1,640 ft (500 m). Studies on bowhead whales
have shown they may be more sensitive than other species to impulsive
noise, as individuals have shown clear changes in diving and breathing
patterns up to 45.4 mi (73 km) from seismic vessels with received
levels as low as 125 dB re 1 [mu]Pa (Malme et al. 1988). Richardson et
al. (1995b) documented bowhead whales exhibiting avoidance behaviors at
a distance of more than 12.4 mi (20 km) from seismic vessels when
received levels were as low as 120 dB re 1 [mu]Pa, although most did
not show active avoidance until 5 mi (8 km) from the source. Although
bowhead whales may avoid the area around seismic surveys, from 3.7 to 5
mi (6 to 8 km) (Koski and Johnson 1987, as cited in Gordon et al.,
2003) out to 12.4 or 18.6 mi (20 or 30 km) (Richardson et al., 1999), a
study by Robertson et al. (2013) supports the idea that behavioral
responses are contextually dependent, and that during seismic
operations, bowhead whales may be less ``available'' for counting due
to alterations in dive behavior but that they may not have completely
vacated the area.
In contrast, noise from seismic surveys was not found to impact
feeding behavior or exhalation rates in western gray whales while
resting or diving off the coast of Russia (Gailey et al., 2007;
Yazvenko et al., 2007); however, the increase in vessel traffic
associated with surveys and the proximity of the vessels to the whales
did affect the orientation of the whales relative to the vessels and
shortened their dive-surface intervals (Gailey et al., 2016). They also
increased their speed and distance from the noise source and have been
documented in one case study swimming towards shore to avoid an
approaching seismic vessel (Gailey et al., 2022). Todd et al. (1996)
found no clear short-term behavioral responses by foraging humpbacks to
explosions associated with construction operations in Newfoundland but
did see a trend of increased rates of net entanglement closer to the
noise source, possibly indicating a reduction in net detection
associated with the noise through masking or TTS. Distributions of fin
and minke whales were modeled with multiple environmental variables and
with the occurrence or absence of seismic surveys, and no evidence of a
decrease in sighting rates relative to seismic activity was found for
either species (Vilela et al., 2016). Their distributions were driven
entirely by environmental variables, particularly those linked to prey,
including warmer sea surface temperatures, higher chlorophyll-a values,
and higher photosynthetically available radiation (a measure of primary
productivity). Sighting rates based on over 8,000 hours of baleen and
toothed whale survey data were compared on regular vessel surveys
versus both active and passive periods of seismic surveys (Kavanagh et
al., 2019). Models of sighting numbers were developed, and it was
determined that baleen whale sightings were reduced by 88 percent
during active and 87 percent during inactive phases of seismic surveys
compared to regular surveys. These results seemed to occur regardless
of geographic location of the survey; however, when only comparing
active versus inactive periods of seismic surveys the geographic
location did seem to affect the change in sighting rates.
Mysticetes seem to be the most behaviorally sensitive taxonomic
group of marine mammals to impulsive sound sources, with possible
avoidance responses occurring out to 18.6 mi (30 km) and vocal changes
occurring in response to sounds over 62.1 mi (100 km) away. However,
they are also the most studied taxonomic group, yielding a larger
sample size and greater chance of finding behavioral responses to
impulsive noise. Also, their responses appear to be behavior-dependent,
with most avoidance responses occurring during migration behavior and
little observed response during feeding behavior. These response
patterns are likely to hold true for impulsive sources used by the
Action Proponents; however, their impulsive sources would largely be
stationary (e.g., explosives fired at a fixed target, small air guns),
and short term (hours rather than days or weeks) versus in the
aforementioned studies, so responses would likely occur in closer
proximity to animals or not at all.
Odontocete responses to impulsive noise are not well studied and
the majority of data have come from seismic

[[Page 32182]]

(i.e., air gun) surveys, pile driving, and construction activities,
while only a few studies have been done to understand how explosive
sounds impact odontocetes. What data are available show they may be
less sensitive than mysticetes to impulsive sound and that responses
occur at closer distances. This may be due to the predominance of low-
frequency sound associated with impulsive sources that propagates
across long distances and overlaps with the range of best hearing for
mysticetes but is below that range for odontocetes. Even harbor
porpoises--shown to be highly sensitive to most sound sources, avoiding
both stationary (e.g., pile driving) and moving (e.g., seismic survey
vessels) impulsive sound sources out to approximately 12.4 mi (20 km)
(e.g., Haelters et al., 2014; Pirotta et al., 2014)--have short-term
responses, returning to an area within hours upon cessation of the
impulsive noise.
Although odontocetes are generally considered less sensitive,
impulsive noise does impact toothed whales in a variety of ways. In one
study, dolphin detections were compared during 30 second periods
before, during, and after underwater detonations near naval mine
neutralization exercises in Virginia Capes Operating Area. Lammers et
al. (2017) found that within 30 seconds after an explosion, the
immediate response was an increase in whistles compared to the 30
seconds before an explosion, and that there was a reduction in dolphin
acoustic activity during the day of and day after the exercise within
3.7 mi (6 km). This held true only during daytime, as nighttime
activity did not appear different than before the exercise, and two
days after the explosion there seemed to be an increase in daytime
acoustic activity, indicating dolphins may have returned to the area or
resumed vocalizations (Lammers et al., 2017). Weaver (2015) documented
potential sex-based differences in behavioral responses to impulsive
noise during construction (including blasting) of a bridge over a
waterway commonly used by bottlenose dolphins, where females decreased
area use and males continued using the area, perhaps indicating
differential habitat uses.
When exposed to multiple impulses from a seismic air gun, Finneran
et al. (2015) noted some captive dolphins turned their heads away from
the source just before the impulse, indicating they could anticipate
the timing of the impulses and may be able to behaviorally mediate the
exposure to reduce their received level. Kavanagh et al. (2019) found
sightings of odontocete whales decreased by 53 percent during active
phases of seismic air gun surveys and 29 percent during inactive phases
compared to control surveys. Heide-Jorgensen et al. (2021) found that
narwhals exposed to air gun noise in an Arctic fjord were sensitive to
seismic vessels over 6.8 mi (11 km) away, even though the small air gun
source reached ambient noise levels around 1.9 mi (3 km) (source level
of 231 dB re 1 [mu]Pa at 1 m) and large air gun source reached ambient
noise levels around 6.2 mi (10 km) (source level 241 dB re 1 [mu]Pa at
1 m). Behavioral responses included changes in swimming speed and
swimming direction away from the impulsive sound source and towards the
shoreline. Changes in narwhal swimming speed was context-dependent and
usually increased in the presence of vessels but decreased (a
``freeze'' response) in response to closely approaching air gun pulses
(Heide-Jorgensen et al., 2021). A cessation of feeding was also
documented, when the impulsive noise was less than 6.2 mi (10 km) away,
although received SELs were less than 130 dB re 1 [mu]Pa\2\s for either
air gun at this distance. However, because of this study's research
methods and criteria, the long-distance responses of narwhals may be
conservatively estimating narwhals' range to behavioral response.
Similarly, harbor porpoises seem to have an avoidance response to
seismic surveys by leaving the area and decreasing foraging activity
within 3.1-6.2 mi (5-10 km) of the survey, as evidenced by both a
decrease in vocalizations near the survey and an increase in
vocalizations at a distance (Pirotta et al., 2014; Thompson et al.,
2013a). The response was short-term, as the porpoises returned to the
area within 1 day upon cessation of the air gun operation.
Sarnoci[nacute]ska et al. (2020) placed autonomous recording devices
near oil and gas platforms and control sites to measure harbor porpoise
acoustic activity during seismic air gun surveys. They noted a dose-
response effect, with the lowest amount of porpoise activity closest to
the seismic vessel (SELsingle shot = 155 dB re 1 [mu]Pa\2\s)
and increasing porpoise activity out to 5 to 7.5 mi (8 to 12 km), and
that distance to the seismic vessel, rather than sound level, was a
better model predictor of porpoise activity. Overall porpoise activity
in the seismic survey area was similar to the control sites
(approximately 9.3 mi (15 km) apart), which may indicate the harbor
porpoises were moving around the area to avoid the seismic vessel
without leaving the area entirely.
Pile driving, another activity that produces impulsive sound,
elicited a similar response in harbor porpoises. Benhemma-Le Gall et
al., 2021 examined changes in porpoise presence and foraging at two
offshore windfarms between control (102-104 dB) and construction
periods (155-161 dB), and found decreased presence (8-17 percent) and
decreased foraging activity (41-62 percent) during construction
periods. Porpoises were displaced up to 7.5 mi (12 km) away from pile
driving and 2.5 mi (4 km) from construction vessels. Multiple studies
have documented strong avoidance responses by harbor porpoises out to
12.4 mi (20 km) during pile driving activity, however, animals returned
to the area after the activity stopped (Brandt et al., 2011; D[auml]hne
et al., 2014; Haelters et al., 2014; Thompson et al., 2010; Tougaard et
al., 2005; Tougaard et al., 2009). When bubble curtains were deployed
around pile driving, the avoidance distance appeared to be reduced by
half to 7.5 mi (12 km), and the animals returned to the area after
approximately 5 hours rather than 1 day later (D[auml]hne et al.,
2017). Further, Bergstr[ouml]m et al. (2014) found that although there
was a high likelihood of acoustic disturbance during wind farm
construction (including pile driving), the impact was short-term, and
Graham et al. (2019) found that the distance at which behavioral
responses of harbor porpoises were likely decreased over the course of
a construction project, suggesting habituation to impulsive pile-
driving noise. Kastelein et al. (2013b) exposed captive harbor
porpoises to impact pile driving noise, and found that respiration
rates increased above 136 dB re 1 [mu]Pa (zero-to-peak), and at higher
sound levels individuals jumped more frequently. When a single harbor
porpoise was exposed to playbacks of impact pile driving noise with
different bandwidths, Kastelein et al. (2022) found the animal's
behavioral response (i.e., swim speed, respiration rate, jumping)
decreased with bandwidth.
Overall, odontocete behavioral responses to impulsive sound sources
are likely species- and context-dependent. Responses might be expected
close to a noise source, under specific behavioral conditions such as
females with offspring, or for sensitive species such as harbor
porpoises, while many other species demonstrate little to no behavioral
response.
Pinnipeds seem to be the least sensitive marine mammal group to
impulsive noise (Richardson et al., 1995b; Southall et al., 2007), and
some may even experience hearing effects before exhibiting a behavioral
response (Southall et al., 2007). Some species

[[Page 32183]]

may be more sensitive and are only likely to respond (e.g., startling,
entering the water, ceasing foraging) to loud impulsive noises in close
proximity, but only for brief periods of time before returning to their
previous behavior. Demarchi et al. (2012) exposed Steller sea lions to
in-air explosive blasts, which resulted in increased activity levels
and often caused re-entry into the water from a hauled out state. These
responses were brief (lasting only minutes) and the animals returned to
haul outs and there were no documented lasting behavioral impacts in
the days following the explosions.
Ringed seals exhibited little or no response to pile driving noise
with mean underwater levels of 157 dB re 1 [mu]Pa and in-air levels of
112 dB re 20 [mu]Pa (Blackwell et al., 2004) while harbor seals vacated
the area surrounding an active pile driving site at estimated received
levels between 166-178 dB re 1 [mu]Pa SPL (peak to peak), returning
within 2 hours of the completion of piling activities (Russell et al.,
2016). Wild-captured gray seals exposed to a startling treatment (sound
with a rapid rise time and a 93 dB sensation level (the level above the
animal's hearing threshold at that frequency)) avoided a known food
source, whereas animals exposed to a non-startling treatment (sound
with a slower rise time but peaking at the same level) did not react or
habituated during the exposure period (G[ouml]tz and Janik, 2011).
These results underscore the importance of the characteristics of an
acoustic signal in predicting an animal's response of habituation.
Hastie et al. (2021) studied how the number and severity of
avoidance events may be an outcome of marine mammal cognition and risk
assessment using captive grey seals. Five individuals were given the
option to forage in a high- or low-density prey patch while
continuously exposed to silence or an anthropogenic noise (pile driving
or tidal turbine operation) playbacks (148 dB re 1 [mu]Pa at 1 m). For
each trial, one prey patch was closer to the source, therefore having a
higher received level in experimental exposures than the other prey
patch. The authors found that foraging success was highest during
silent periods and that the seals avoided both anthropogenic noises
with higher received levels when the prey density was limited (low-
density prey patch). The authors concluded that the seals made foraging
decisions within the trials based on both the energetic value of the
prey patch (low-density corresponding to low energetic value, high-
density corresponding to high energetic value), and the nature and
location of the acoustic signal relative to the prey patches of
different value.
Pinniped responses to Navy missile launches are limited to
observations at SNI on the PMSR, and there are extensive observations
from this site over more than two decades (Burke, 2017; Holst et al.,
2011; Holst and Greene Jr., 2005; Holst and Greene Jr., 2008; Holst and
Greene Jr., 2010; Navy, 2021a, 2021b, 2022; Ugoretz, 2014, 2015, 2016;
Ugoretz and Greene Jr., 2012), including observations of northern
elephant seals, California sea lions, and harbor seals) to every launch
from SNI was required under these authorizations of launch activity.
The results from these monitoring efforts (2001-2024) are summarized in
this section. Over twenty years of observations of pinniped behavioral
responses to land-based rocket and missile launches at VSFB are also
available (Force, 2022).The observations at VSFB are consistent with
those from SNI, but notable findings from VSFB are detailed below.
Since launches were relatively infrequent, and of such brief
duration, it is unlikely that pinnipeds near the SNI launch sites were
habituated to launch sounds. The most common type of response to
airborne noise from missile and target launches at SNI was a momentary
``alert'' response. When the animals heard or otherwise detected the
launch, they were likely to become alert and interrupt prior activities
to pay attention to the launch. For both northern elephant seals and
California sea lions, the proportion of animals that moved was
significantly related to the closest point of approach of the vehicle
or the weighted SEL of the event (based on pinniped in-air M-weighting
function from Southall et al. (2007). These relationships were not
evident for harbor seals, despite this species being the most
susceptible to disturbance (Holst et al., 2011). In cases where animals
were displaced from normal activity, the displacement was typically
short in duration (5-15 minutes, although some harbor seals left their
haulout site until the following low tide when the haulout site was
again accessible).
Observations indicated that elephant seals rarely showed more than
a momentary alert, even when exposed to noise levels or types that
caused nearby harbor seals and California sea lions to react more. This
was also the case for northern fur seals at VSFB. Most elephant seals
raised their heads briefly upon hearing the launch sounds and then
quickly returned to their previous activity pattern (usually sleeping).
During some launches, a small proportion of northern elephant seals
moved a short distance on the beach or into the water, away from their
resting site, but settled within minutes. Because of this, elephant
seals were not specifically targeted for launch monitoring after 2010
(75 FR 71672, November 24, 2010), although in subsequent years they
were often in the field of view when monitoring other species.
California sea lions (especially the young animals) exhibited more
response than elephant seals, and responses varied by individual and
age group. Some exhibited brief startle responses and increased
vigilance for a short period after each launch. Others, particularly
pups that were playing in groups along the margin of haulouts, appeared
to react more vigorously. A greater proportion of hauled-out sea lions
typically responded or entered the water when launch sounds were
louder.
Harbor seals tended to be the most sensitive of the three target
species, and during the majority of launches at SNI, most harbor seals
left their haulout sites on rocky ledges to enter the water. In some
cases, harbor seals returned to their haulout after a short period of
time, while in other cases they did not return during the duration of
the video-recording period (which sometimes extended up to several
hours after a launch). During the day following a launch, harbor seals
usually hauled out again at these sites (Holst and Lawson, 2002). The
height of the tide following a launch event may have played a
significant role in when harbor seals were able to return to a haulout
site.
There were no observations of any sonic booms or stampedes at SNI
and, specifically for the monitored launches at SNI from 2001 to 2024,
there were no observed launch-related injuries or deaths (National
Marine Fisheries Service, 2019b; Naval Air Warfare Center Weapons
Division, 2018). On several occasions, harbor seals and California sea
lion adults moved over pups (which can also happen without the presence
of an anthropogenic noise) as the animals moved in response to the
launches, but the pups did not appear to be injured. On one occasion, a
stampede of California sea lions was observed in response to a sonic
boom at VSFB. This was thought to have resulted from a particularly
high amplitude sonic boom and is noted as an isolated incident.
Responses Due to Vessel Noise--
Mysticetes have varied responses to vessel noise and presence, from
having no response to approaching vessels to

[[Page 32184]]

exhibiting an avoidance response by both horizontal (swimming away) and
vertical (increased diving) movement (Baker et al., 1983; Fiori et al.,
2019; Gende et al., 2011; Watkins, 1981). Avoidance responses include
changing swim patterns, speed, or direction (Jahoda et al., 2003),
remaining submerged for longer periods of time (Au and Green, 2000),
and performing shallower dives with more frequent surfacing. Behavioral
responses to vessels range from smaller-scale changes, such as altered
breathing patterns (e.g., Baker et al., 1983; Jahoda et al., 2003), to
larger-scale changes such as a decrease in apparent presence (Anderwald
et al., 2013). Other common behavioral responses include changes in
vocalizations, surface time, feeding and social behaviors (Au and
Green, 2000; Dunlop, 2019; Fournet et al., 2018; Machernis et al.,
2018; Richter et al., 2003; Williams et al., 2002a). For example, North
Atlantic right whales (NARWs) have been reported to increase the
amplitude or frequency of their vocalizations or call at a lower rate
in the presence of increased vessel noise (Parks et al., 2007; Parks et
al., 2011) but generally demonstrate little to no response to vessels
or sounds from approaching vessels and often continue to use habitats
in high vessel traffic areas (Nowacek et al. 2004a). This lack of
response may be due to habituation to the presence and associated noise
of vessels in NARW habitat or may be due to propagation effects that
may attenuate vessel noise near the surface (Nowacek et al., 2004a;
Terhune and Verboom, 1999).
Similarly, sei whales have been observed ignoring the presence of
vessels entirely and even pass close to vessels (Reeves et al., 1998).
Historically, fin whales tend to ignore vessels at a distance (Watkins,
1981) or habituate to vessels over time (Watkins, 1986) but still
demonstrate vocal modifications (e.g., decreased frequency parameters
of calls) during vessel traffic. Ramesh et al. (2021) found that fin
whale calls in Ireland were less likely to be detected for every 1 dB
re 1 [mu]Pa/minute increase in shipping noise levels. In the presence
of tour boats in Chile, fin whales were changing their direction of
movement more frequently, with less linear movement than occurred
before the boats arrived; this behavior may represent evasion or
avoidance of the boats (Santos-Carvallo et al., 2021). The increase in
travel swim speeds after the vessels departed may be related to the
rapid speeds at which the vessels traveled, sometimes in front of fin
whales, leading to additional avoidance behavior post-exposure.
Mysticete behavioral responses to vessels may also be affected by
vessel behavior (Di Clemente et al., 2018; Fiori et al., 2019).
Avoidance responses occurred most often after ``J'' type vessel
approaches (i.e., traveling parallel to the whales' direction of
travel, then overtaking the whales by turning in front of the group)
compared to parallel or direct approaches. Mother humpbacks were
particularly sensitive to direct and J type approaches and spent
significantly more time diving in response (Fiori et al., 2019). The
presence of a passing vessel did not change the behavior of resting
humpback whale mother-calf pairs, but fast vessels with louder low-
frequency weighted source levels (173 dB re 1 [mu]Pa, equating to
weighted received levels of 133 dB re 1 [mu]Pa) at an average distance
of 328 ft (100 m) resulted in a decreased resting behavior and
increases in dives, swim speeds, and respiration rates (Sprogis et al.,
2020). Humpback whale responses to vessel disturbance were dependent on
their behavioral state. Di Clemente et al. (2018) found that when
vessels passed within 1,640 ft (500 m) of humpback whales, individuals
would continue to feed if already engaged in feeding behavior but were
more likely to start swimming if they were surface active when
approached. In response to an approaching large commercial vessel in an
area of high ambient noise levels (125-130 dB re 1 [mu]Pa), a tagged
female blue whale turned around mid-ascent and descended perpendicular
to the vessel's path (Szesciorka et al., 2019). The whale did not
respond until the vessel's closest point of approach (328 ft (100 m)
distance, 135 dB re 1 [mu]Pa RMS), which was 10 dB above the ambient
noise levels. After the vessel passed, the whale ascended to the
surface again with a three-minute delay.
Overall, mysticete responses to vessel noise and traffic are
varied, and habituation or changes to vocalization are predominant
long-term responses. When baleen whales do avoid vessels, they seem to
do so by altering their swim and dive patterns to move away from the
vessel. Although a lack of response in the presence of a vessel may
minimize potential disturbance from passing vessels, it does increase
the whales' vulnerability to vessel strike, which may be of greater
concern for mysticetes than vessel noise.
Odontocete responses due to vessel noise are varied and context-
dependent, and it is difficult to separate the impacts of vessel noise
from the impacts of vessel presence. Vessel presence has been shown to
interrupt feeding behavior in delphinids in some studies (Meissner et
al., 2015; Pirotta et al., 2015b) while a recent study by Mills et al.
(2023) found that, in an important foraging area, bottlenose dolphins
may continue to forage and socialize even while constantly exposed to
high vessel traffic. Ng and Leung (2003) found that the type of vessel,
approach, and speed of approach can all affect the probability of a
negative behavioral response and, similarly, Guerra et al. (2014)
documented varied responses in group structure and vocal behavior.
While most odontocetes have documented neutral responses to
vessels, avoidance (Bejder et al., 2006a; W[uuml]rsig et al., 1998) and
attraction (Norris and Prescott, 1961; Ritter, 2002; Shane et al.,
1986; Westdal et al., 2023; W[uuml]rsig et al., 1998) behaviors have
also been observed (Hewitt, 1985). Archer et al. (2010) compared the
responses of dolphin populations far offshore that were often targeted
by tuna fisheries to populations closer (less than 100 nmi (185.2 km))
to shore and found the fisheries-associated populations (spotted,
spinner, and common dolphins) showed evasive behavior when approached
by vessels while those nearshore species not associated with offshore
fisheries (coastal spotted and bottlenose dolphins) tended to be
attracted to vessels.
Arranz et al. (2021) used different engine types to determine
whether behavioral responses of short-finned pilot whales were
attributable to vessel noise, vessel presence, or both. Mother-calf
pairs were approached by the same vessel outfitted with either
``quiet'' electric engines or ``noisy'' traditional combustion engines,
controlling for approach speed and distance. Arranz et al. (2021) found
mother pilot whales rested less and calves nursed less in response to
both types of engines compared to control conditions, but only the
``noisy'' engine caused significant impacts (29 percent and 81 percent,
respectively).
Smaller vessels tend to generate more noise in higher frequency
bands, are more likely to approach odontocetes directly, and spend more
time near an animal. Carrera et al. (2008) found tour boat activity can
cause short-term displacement of dolphins, and Haviland-Howell et al.
(2007) documented longer term or repetitive displacement of dolphins
due to chronic vessel noise. Delphinid behavioral states also change in
the presence of small tour vessels that often approach animals: travel
and resting increases, foraging and social behavior decreases, and
animals move closer together (Cecchetti et al., 2017; Clarkson et al.,

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2020; Kassamali-Fox et al., 2020; Meissner et al., 2015). Most studies
on behavioral responses of bottlenose dolphins to vessel traffic show
at least short-term changes in behavior, activities, or vocalization
patterns when vessels are nearby (Acevedo, 1991; Arcangeli and Crosti,
2009; Berrow and Holmes, 1999; Fumagalli et al., 2018; Gregory and
Rowden, 2001; Janik and Thompson, 1996; Lusseau, 2004; Marega et al.,
2018; Mattson et al., 2005; Perez-Ortega et al., 2021; Puszka et al.,
2021; Scarpaci et al., 2000).
Information is limited on beaked whale responses to vessel noise,
but W[uuml]rsig et al. (1998) noted that most beaked whales seem to
exhibit avoidance behaviors when exposed to vessels and beaked whales
may respond to all anthropogenic noise (i.e., sonar, vessel) at similar
sound levels (Aguilar de Soto et al., 2006; Tyack et al., 2011; Tyack,
2009). The information available includes a disruption of foraging by a
vocalizing goose-beaked whale in the presence of a passing vessel
(Aguilar de Soto et al., 2006) and restriction of group movement, or
possibly reduction in the number of individuals clicking within the
group, after exposure to broadband (received level of 135 dB re 1
[mu]Pa) vessel noise up to at least 3.2 mi (5.2 km) away from the
source, though no change in duration of Blainville's beaked whale
foraging dives was observed (Pirotta et al., 2012).
Porpoises and small delphinids are known to be sensitive to vessel
noise, as well. Frankish et al. (2023) found harbor porpoises more
likely to avoid large commercial vessels via horizontal movement during
the day and vertical movement at night, which supports previous
research that the species routinely avoids large, motorized vessels
(Polacheck and Thorpe, 1990). Harbor porpoises have also been
documented responding to vessels with increased changes in behavioral
state and significantly decreased feeding (Akkaya Bas et al., 2017),
fewer clicks (Sairanen, 2014), and fewer prey capture attempts and have
disrupted foraging when vessels pass closely and noise levels are
higher (Wisniewska et al., 2018). Habituation to vessel noise and
presence was observed for a resident population of harbor porpoises
that was in regular proximity to vessel traffic (32.8 ft to 0.6 mi (10
m to 1 km) away); the population had no response in 74 percent of
interactions and an avoidance response in 26 percent of interactions.
It should be noted that fewer responses in populations of odontocetes
regularly subjected to high levels of vessel traffic could be a sign of
habituation, or it could be that the more sensitive individuals in the
population have abandoned that area of higher human activity.
Most avoidance responses were the result of fast-moving or steady
plane-hulling motorized vessels and the vessel type and speed were
considered to be more relevant than vessel presence, as few responses
were observed to non-motorized or stationary vessels (Oakley et al.,
2017). Similarly, Akkaya Bas et al. (2017) found that when fast moving
vessels were within 164 ft (50 m) of harbor porpoises, there was an 80
percent probability of change in swimming direction but only a 40
percent probability of change when vessels were beyond 1,312.3 ft (400
m). Frankish et al. (2023) found that harbor porpoises were most likely
to avoid vessels less than 984.3 ft (300 m) away but, 5-10 percent of
the time, they would also respond to vessels more than 1.2 mi (2 km)
away, signifying that they were not just attuning to vessel presence,
but to vessel noise as well.
Although most vessel noise is constrained to frequencies below 1
kHz, at close ranges vessel noise can extend into mid- and high
frequencies (into the tens of kHz) (Hermannsen et al., 2014; Li et al.,
2015) and it is these frequencies that harbor porpoises are likely
responding to; the mean M-weighted received SPL threshold for a
response at these frequencies is 123 dB re 1 [mu]Pa (Dyndo et al.,
2015). M-weighting functions are generalized frequency weightings for
various groups of marine mammals that were defined by Southall et al.
(2007) based on known or estimated auditory sensitivity at different
frequencies and are used to characterize auditory effects of strong
sounds. Hermannsen et al. (2019) estimated that noise in the 16 kHz
frequency band resulting from small recreational vessels could cause
behavioral directions in harbor porpoises and could be elevated up to
124 dB re 1 [mu]Pa and raise ambient noise levels by a maximum of 51
dB. The higher noise levels were associated with vessel speed and
range, which exceeded the threshold levels found by Dyndo et al. (2015)
and Wisniewska et al. (2018) by 49-85 percent of events with high
levels of vessel noise.
Lusseau and Bejder (2007) have reported some long-term consequences
of vessel noise on odontocetes but, overall, there is little
information on the long-term and cumulative impacts of vessel noise
(National Academies of Sciences Engineering and Medicine, 2017;
National Marine Fisheries Service, 2007). Many researchers speculate
that long-term impacts may occur on odontocete populations that
experience repeated interruption of foraging behaviors (Stockin et al.,
2008), and Southall et al. (2021) indicates that, in many contexts, the
localized and coastal home ranges typical of many species make them
less resilient to this chronic stressor than mysticetes.
Context and experience likely play a role in pinnipeds response to
vessel noise, which vary from negative responses including increased
vigilance and alerting to avoidance to reduced time spent doing
biologically important activities (e.g., resting, feeding, and nursing)
(Martin et al., 2023a; Martin et al., 2022; Mikkelsen et al., 2019;
Richardson et al., 1995b) to attraction or lack of observable response
(Richardson et al., 1995b). More severe responses, like flushing, could
be more detrimental to individuals during biologically important
activities and times, such as during pupping season. Blundell and
Pendleton (2015) found that vessel presence reduces haul out time of
Alaskan harbor seals during pupping season and larger vessels elicit
stronger responses. Cates and Acevedo-Guti[eacute]rrez (2017) modeled
harbor seal responses to passing vessels at haul out sites in less
trafficked areas and found the model best predicting flushing behavior
included number of boats, type of boats, and distance of seals to
boats. The authors noted flushing occurred more in response to non-
motorized vessels (e.g., kayaks), likely because they tended to pass
closer (82 to 603.7 ft (25 to 184 m)) to haul out sites than motorized
vessels (180.4 to 1,939 ft (55 to 591 m)) and tended to occur in groups
rather than as a single vessel.
Cape fur seals were also more responsive to vessel noise at sites
with a large breeding colony than at sites with lower abundances of
conspecifics (Martin et al., 2023a). A field study of harbor and gray
seals showed that seal responses to vessels included interruption of
resting and foraging during times when vessel noise was increasing or
at its peak (Mikkelsen et al., 2019). And, although no behavioral
differences were observed in hauled out wild cape fur seals exposed to
low (60-64 dB re 20 [mu]Pa RMS SPL), medium (64-70 dB) and high-level
(70-80 dB) vessel noise playbacks, mother-pup pairs spent less time
nursing (15-31 percent) and more time awake (13-26 percent), vigilant
(7-31 percent), and mobile (2-4 percent) during vessel noise conditions
compared to control conditions (Martin et al., 2022).
Masking
Sound can disrupt behavior through masking, or interfering with, an
animal's ability to detect, recognize, interpret, or

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discriminate between acoustic signals of interest (e.g., those used for
intraspecific communication and social interactions, prey detection,
predator avoidance, or navigation) (Clark et al., 2009; Richardson et
al., 1995; Erbe and Farmer, 2000; Tyack, 2000; Erbe et al., 2016;
Branstetter and Sills, 2022). Masking occurs when the receipt of a
sound is interfered with by another coincident sound at similar
frequencies and at similar or higher intensity and may occur whether
the coincident sound is natural (e.g., snapping shrimp, wind, waves,
precipitation) or anthropogenic (e.g., shipping, sonar, seismic
exploration) in origin.
As described in detail in appendix D, section D.4.4 (Masking), of
the 2024 HCTT Draft EIS/OEIS, the ability of a noise source to mask
biologically important sounds depends on the characteristics of both
the noise source and the signal of interest (e.g., signal-to-noise
ratio, temporal variability, direction), in relation to each other and
to an animal's hearing abilities (e.g., sensitivity, frequency range,
critical ratios, frequency discrimination, directional discrimination,
age, or TTS hearing loss), and existing ambient noise and propagation
conditions. Masking these acoustic signals can disturb the behavior of
individual animals, groups of animals, or entire populations. Masking
can lead to behavioral changes including vocal changes (e.g., Lombard
effect, increasing amplitude, or changing frequency), cessation of
foraging, and leaving an area, to both signalers and receivers, in an
attempt to compensate for noise levels (Erbe et al., 2016).
Most research on auditory masking is focused on energetic masking,
or the ability of the receiver (i.e., listener) to detect a signal in
noise. However, from a fitness perspective, both signal detection and
signal interpretation are necessary for success. This type of masking
is called informational masking and occurs when a signal is detected by
an animal but the meaning of that signal has been lost. Few data exist
on informational masking in marine mammals but studies have shown that
some recognition of predator cues might be missed by species that are
preyed upon by killer whales if killer whale vocalizations are masked
(Cur[eacute] et al., 2016; Cur[eacute] et al., 2015; Deecke et al.,
2002; Isojunno et al., 2016; Visser et al., 2016). Von Benda-Beckman et
al. (2021) modeled the effect of pulsed and continuous active sonars
(CAS) on sperm whale echolocation and found that sonar sounds could
reduce the ability of sperm whales to find prey under certain
conditions.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (i.e., masking) sound is man-made, it may be considered
harassment when disrupting natural behavioral patterns to the point
where the behavior is abandoned or significantly altered. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which only occurs during the sound exposure.
Because masking (without resulting in threshold shift) is not
associated with abnormal physiological function, it is not considered a
physiological effect, but rather a potential behavioral effect.
Richardson et al. (1995) argued that the maximum radius of
influence of anthropogenic noise (including broadband low-frequency
sound transmission) on a marine mammal is the distance from the source
to the point at which the noise can barely be heard. This range is
determined by either the hearing sensitivity (including critical
ratios, or the lowest signal-to-noise ratio in which animals can detect
a signal) of the animal (Finneran and Branstetter, 2013; Johnson et
al., 1989; Southall et al., 2000) or the background noise level
present. Masking is most likely to affect some species' ability to
detect communication calls and natural sounds (i.e., surf noise, prey
noise, etc.) (Richardson et al., 1995).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009; Matthews et al., 2016) and may result in energetic
or other costs as animals change their vocalization behavior (e.g.,
Miller et al., 2000; Foote et al., 2004; Parks et al., 2007; Di Iorio
and Clark, 2009; Holt et al., 2009). Masking can be reduced in
situations where the signal and noise come from different directions
(Richardson et al., 1995), through amplitude modulation of the signal,
or through other compensatory behaviors (Houser and Moore, 2014).
Masking can be tested directly in captive species, but in wild
populations it must be either modeled or inferred from evidence of
masking compensation. There are few studies addressing real-world
masking sounds likely to be experienced by marine mammals in the wild
(e.g., Cholewiak et al., 2018; Branstetter and Sills, 2022; Branstetter
et al., 2024).
High-frequency sounds may mask the echolocation calls of toothed
whales. Human data indicate low-frequency sound can mask high-frequency
sounds (i.e., upward masking). Studies on captive odontocetes by Au et
al. (1974; 1985; 1993) indicate that some species may use various
processes to reduce masking effects (e.g., adjustments in echolocation
call intensity or frequency as a function of background noise
conditions). Odontocete hearing is highly directional at high
frequencies, facilitating echolocation in masked conditions (Au and
Moore, 1984). A study by Nachtigall et al., (2018) showed that false
killer whales adjust their hearing to compensate for ambient sounds and
the intensity of returning echolocation signals.
Impacts on signal detection, measured by masked detection
thresholds, are not the only important factors to address when
considering the potential effects of masking. As marine mammals use
sound to recognize conspecifics, prey, predators, or other biologically
significant sources (Branstetter et al., 2016), it is also important to
understand the impacts of masked recognition thresholds (i.e.,
informational masking). Branstetter et al. (2016) measured masked
recognition thresholds for whistle-like sounds of bottlenose dolphins
and observed that they are approximately 4 dB above detection
thresholds (energetic masking) for the same signals. Reduced ability to
recognize a conspecific call or the acoustic signature of a predator
could have severe negative impacts. Branstetter et al. (2016) observed
that if ``quality communication'' is set at 90 percent recognition the
output of communication space models (which are based on 50 percent
detection) would likely result in a significant decrease in
communication range.
As marine mammals use sound to recognize predators (Allen et al.,
2014; Cummings and Thompson, 1971; Cure et al., 2015; Fish and Vania,
1971), the presence of masking noise may also prevent marine mammals
from responding to acoustic cues produced by their predators,
particularly if it occurs in the same frequency band. For example,
harbor seals that reside in the coastal waters of British Columbia are
frequently targeted by mammal-eating killer whales. The seals
acoustically

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discriminate between the calls of mammal-eating and fish-eating killer
whales (Deecke et al., 2002), a capability that should increase
survivorship while reducing the energy required to identify all killer
whale calls. Similarly, sperm whales (Cur[eacute] et al., 2016;
Isojunno et al., 2016), long-finned pilot whales (Visser et al., 2016),
and humpback whales (Cur[eacute] et al., 2015) changed their behavior
in response to killer whale vocalization playbacks. The potential
effects of masked predator acoustic cues depends on the duration of the
masking noise and the likelihood of a marine mammal encountering a
predator during the time that detection and recognition of predator
cues are impeded.
Redundancy and context can also facilitate detection of weak
signals. These phenomena may help marine mammals detect weak sounds in
the presence of natural or anthropogenic noise. Most masking studies in
marine mammals present the test signal and the masking noise from the
same direction. The dominant background noise may be highly directional
if it comes from a particular anthropogenic source such as a vessel or
industrial site. Directional hearing may significantly reduce the
masking effects of these sounds by improving the effective signal-to-
noise ratio.
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most of the increase from distant commercial shipping
(Hildebrand, 2009; Cholewiak et al., 2018). All anthropogenic sound
sources, but especially chronic and lower-frequency signals (e.g., from
commercial vessel traffic), contribute to elevated ambient sound
levels, thus intensifying masking for marine mammals.
Masking Due to Sonar and Other Transducers--
The functional hearing ranges of mysticetes, odontocetes, and
pinnipeds underwater overlap the frequencies of the sonar sources used
in the Action Proponents' LFAS/MFAS/high-frequency active sonar (HFAS)
training and the Navy's testing exercises. Additionally, almost all
affected species' vocal repertoires span across the frequencies of
these sonar sources used by the Action Proponents. Masking by LFAS or
MFAS with relatively low-duty cycles is not anticipated (or would be of
very short duration) for most cetaceans as sonar signals occur over a
relatively short duration and narrow bandwidth (overlapping with only a
small portion of the hearing range). LFAS could overlap in frequency
with mysticete vocalizations, however LFAS does not overlap with
vocalizations for most marine mammal species. For example, in the
presence of LFAS, humpback whales were observed to increase the length
of their songs (Fristrup et al., 2003; Miller et al., 2000),
potentially due to the overlap in frequencies between the whale song
and the LFAS. While dolphin whistles and MFAS are similar in frequency,
masking is not anticipated (or would be of very short duration) due to
the low-duty cycle and short durations of most sonars.
As described in additional detail in the 2024 HCTT Draft EIS/OEIS,
high duty-cycle or CAS have more potential to mask vocalizations. These
sonars transmit more frequently (greater than 80 percent duty cycle)
than traditional sonars, but typically at lower source levels. HFAS,
such as pingers that operate at higher repetition rates, also operate
at lower source levels and have faster attenuation rates due to the
higher frequencies used. These lower source levels limit the range of
impacts, however, compared to traditional sonar systems, individuals
close to the source are likely to experience masking at longer time
scales. The frequency range at which high-duty cycle systems operate
overlaps the vocalization frequency of many odontocetes. Continuous
noise at the same frequency of communicative vocalizations may cause
disruptions to communication, social interactions, and acoustically
mediated cooperative behaviors (S[oslash]rensen et al., 2023) such as
foraging and mating. Similarly, because the high-duty cycle or CAS
includes mid-frequency sources, there is also the potential for the
mid-frequency sonar signals to mask important environmental cues (e.g.,
predator or conspecific acoustic cues), possibly affecting survivorship
for targeted animals. Spatial release from masking may occur with
higher duty cycle or CAS.
While there are currently few studies of the impacts of high-duty
cycle sonars on marine mammals, masking due to these systems is likely
analogous to masking produced by other continuous sources (e.g., vessel
noise and low-frequency cetaceans), and would likely have similar
short-term consequences, though longer in duration due to the duration
of the masking noise. These may include changes to vocalization
amplitude and frequency (Brumm and Slabbekoorn, 2005; Hotchkin and
Parks, 2013) and behavioral impacts such as avoidance of the area and
interruptions to foraging or other essential behaviors (Gordon et al.,
2003). Long-term consequences could include changes to vocal behavior
and vocalization structure (Foote et al., 2004; Parks et al., 2007),
abandonment of habitat if masking occurs frequently enough to
significantly impair communication (Brumm and Slabbekoorn, 2005), a
potential decrease in survivorship if predator vocalizations are masked
(Brumm and Slabbekoorn, 2005), and a potential decrease in recruitment
if masking interferes with reproductive activities or mother-calf
communication (Gordon et al., 2003).
Von Benda-Beckmann et al. (2021) modeled the effect of pulsed and
continuous 1 to 2 kHz active sonar on sperm whale echolocation clicks
and found that the presence of upper harmonics in the sonar signal
increased masking of clicks produced in the search phase of foraging
compared to buzz clicks produced during prey capture. Different levels
of sonar caused intermittent to continuous masking (120 to 160 dB re 1
[mu]Pa\2\, respectively), but varied based on click level, whale
orientation, and prey target strength. CAS resulted in a greater
percentage of time that echolocation clicks were masked compared to
pulsed active sonar. This means that sonar sounds could reduce the
ability of sperm whales to find prey under certain conditions. However,
echoes from prey are most likely spatially separated from the sonar
source, and so spatial release from masking would be expected.
Masking Due to Impulsive Noise--
Impulsive sound sources, including explosions, are intense and
short in duration. Since impulsive noise is intermittent, the length of
the gap between sounds (i.e., duty-cycle) and received level are
relevant when considering the potential for masking. Impulsive sounds
with lower duty cycles or lower received levels are less likely to
result in masking than higher duty cycles or received levels. There are
no direct observations of masking in marine mammals due to exposure to
explosive sources. Potential masking from explosive sounds or weapon
noise is likely similar to masking studied for other impulsive sounds,
such as air guns.
Masking of mysticete calls could occur due to the overlap between
their low-frequency vocalizations and the dominant frequencies of
impulsive sources (Castellote et al., 2012; Nieukirk

[[Page 32188]]

et al., 2012). For example, blue whale feeding/social calls increased
when seismic exploration was underway (Di Lorio and Clark, 2010),
indicative of a possible compensatory response to masking effects of
the increased noise level. However, mysticetes that call at higher
rates are less likely to be masked by impulsive noise with lower duty
cycles (Clark et al., 2009) because of the decreased likelihood that
the noise would overlap with the calls, and because of dip listening.
Field observations of masking effects such as vocal modifications are
difficult to interpret because when recordings indicate that call rates
decline, this could be caused by (1) animals calling less frequently
(i.e., actual noise-induced vocal modifications), (2) the calls being
masked from the recording hydrophone due to the noise (e.g., animals
are not calling less frequently but are being detected less
frequently), or (3) the animals moving away from the noise, or any
combination of these causes (Blackwell et al., 2013; Cerchio et al.,
2014).
Masking of pinniped communication sounds at 100 Hz center frequency
is possible when vocalizations occur at the same time as an air gun
pulse (Sills et al., 2017). This might result in some percentage of
vocalizations being masked if an activity such as a seismic survey is
being conducted in the vicinity, even when the sender and receiver are
near one another. Release from masking due to ``dip listening'' is
likely in this scenario.
While a masking effect of impulsive noise can depend on the
received level (Blackwell et al., 2015) and other characteristics of
the noise, the vocal response of the affected animal to masking noise
is an equally important consideration for inferring overall impacts to
an animal. It is possible that the receiver would increase the rate
and/or level of calls to compensate for masking; or, conversely, cease
calling.
In general, impulsive noise has the potential to mask sounds that
are biologically important for marine mammals, reducing communication
space or resulting in noise-induced vocal modifications that might
impact marine mammals. Masking by close-range impulsive sound sources
is most likely to impact marine mammal communication.
Masking Due to Vessel Noise--
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources such as vessels. Several studies
have shown decreases in marine mammal communication space and changes
in behavior as a result of the presence of vessel noise. For example,
North Atlantic right whales were observed to shift the frequency
content of their calls upward while reducing the rate of calling in
areas of increased anthropogenic noise (Parks et al., 2007) as well as
increasing the amplitude (intensity) of their calls (Parks, 2009; Parks
et al., 2011). Fournet et al. (2018) observed that humpback whales in
Alaska responded to increasing ambient sound levels (natural and
anthropogenic) by increasing the source levels of their calls (non-song
vocalizations). Clark et al. (2009) also observed that right whales
communication space decreased by up to 84 percent in the presence of
vessels (Clark et al., 2009). Cholewiak et al. (2018) also observed
loss in communication space in Stellwagen National Marine Sanctuary for
North Atlantic right whales, fin whales, and humpback whales with
increased ambient noise and shipping noise. Gabriele et al. (2018)
modeled the effects of vessel traffic sound on communication space in
Glacier Bay National Park in Alaska and found that typical summer
vessel traffic in Glacier Bay National Park causes losses of
communication space to singing whales (reduced by 13-28 percent),
calling whales (18-51 percent), and roaring seals (32-61 percent),
particularly during daylight hours and even in the absence of cruise
ships. Dunlop (2019) observed that an increase in vessel noise reduced
modeled communication space and resulted in significant reduction in
group social interactions in Australian humpback whales. However,
communication signal masking did not fully explain this change in
social behavior in the model, indicating there may also be an
additional effect of the physical presence of the vessel on social
behavior (Dunlop, 2019). Although humpback whales off Australia did not
change the frequency or duration of their vocalizations in the presence
of ship noise, their source levels were lower than expected based on
source level changes to wind noise, potentially indicating some signal
masking (Dunlop, 2016). Multiple delphinid species have also been shown
to increase the minimum or maximum frequencies of their whistles in the
presence of anthropogenic noise and reduced communication space (e.g.,
Holt et al., 2009; Holt et al., 2011; Gervaise et al., 2012; Williams
et al., 2014; Hermannsen et al., 2014; Papale et al., 2015; Liu et al.,
2017).
Other Physiological Response
Physiological stress is a natural and adaptive process that helps
an animal survive changing conditions. When an animal perceives a
potential threat, whether or not the stimulus actually poses a threat,
a stress response is triggered (Selye, 1950; Moberg, 2000; Sapolsky,
2005). Once an animal's central nervous system perceives a threat, it
mounts a biological response or defense that consists of a combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses.
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and distress is the biotic cost
of the response. During a stress response, an animal uses glycogen
stores that can be quickly replenished once the stress is alleviated.
In such circumstances, the cost of the stress response would not pose
serious fitness consequences. However, when an animal does not have
sufficient energy reserves to satisfy the energetic costs of a stress
response, energy resources must be diverted from other biotic
functions. For example, when a stress response diverts energy away from
growth in young animals, those animals may experience stunted growth.
When a stress response diverts energy from a fetus, an animal's
reproductive success and its fitness will suffer. In these cases, the
animals will have entered a pre-pathological or pathological state
which is called ``distress'' (Selye, 1950) or ``allostatic loading''
(McEwen and Wingfield, 2003). This pathological state of distress will
last until the animal replenishes its energetic reserves sufficiently
to restore normal function.
According to Moberg (2000), in the case of many stressors, an
animal's first and sometimes most economical (in terms of biotic costs)
response is behavioral avoidance of the potential stressor or avoidance
of continued exposure to a stressor. An animal's second line of defense
to stressors involves the sympathetic part of the autonomic nervous
system and the classical ``fight or flight'' response, which includes
the cardiovascular system, the gastrointestinal system, the exocrine
glands, and the adrenal medulla to produce changes in heart rate, blood
pressure, and gastrointestinal activity that humans commonly associate
with ``stress.'' These responses have a relatively short duration and
may or may not have significant long-term effect on an animal's
welfare.

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An animal's third line of defense to stressors involves its
neuroendocrine systems or sympathetic nervous systems; the system that
has received the most study has been the hypothalamus-pituitary-adrenal
(HPA) system (also known as the HPA axis in mammals or the
hypothalamus-pituitary-interrenal axis in fish and some reptiles).
Unlike stress responses associated with the autonomic nervous system,
virtually all neuro-endocrine functions that are affected by stress,
including immune competence, reproduction, metabolism, and behavior,
are regulated by pituitary hormones. Stress-induced changes in the
secretion of pituitary hormones have been implicated in failed
reproduction (Moberg, 1987; Rivier and Rivest, 1991), altered
metabolism (Elasser et al., 2000), reduced immune competence (Blecha,
2000), and behavioral disturbance (Moberg, 1987; Blecha, 2000).
Increases in the circulation of glucocorticosteroids (cortisol,
corticosterone, and aldosterone in marine mammals; see Romano et al.,
2004) have been equated with stress for many years.
Marine mammals naturally experience stressors within their
environment and as part of their life histories. Changing weather and
ocean conditions, exposure to disease and naturally occurring toxins,
lack of prey availability, and interactions with predators all
contribute to the stress a marine mammal experiences (Atkinson et al.,
2015). Breeding cycles, periods of fasting, social interactions with
members of the same species, and molting (for pinnipeds) are also
stressors, although they are natural components of an animal's life
history. Anthropogenic activities have the potential to provide
additional stressors beyond those that occur naturally (e.g., fishery
interactions, pollution, tourism, ocean noise) (Fair et al., 2014;
Meissner et al., 2015; Rolland et al., 2012).
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005; Reneerkens et al., 2002;
Thompson and Hamer, 2000). However, it should be noted (and as is
described in additional detail in the 2024 HCTT Draft EIS/OEIS) that
our understanding of the functions of various stress hormones (e.g.,
cortisol), is based largely upon observations of the stress response in
terrestrial mammals. Atkinson et al., (2015) note that the endocrine
response of marine mammals to stress may not be the same as that of
terrestrial mammals because of the selective pressures marine mammals
faced during their evolution in an ocean environment. For example, due
to the necessity of breath-holding while diving and foraging at depth,
the physiological role of epinephrine and norepinephrine (the
catecholamines) in marine mammals might be different than in other
mammals. Relatively little information exists on the linkage between
anthropogenic sound exposure and stress in marine mammals, and even
less information exists on the ultimate consequences of sound-induced
stress responses (either acute or chronic). Most studies to date have
focused on acute responses to sound either by measuring catecholamines,
a neurohormone, or heart rate as a proxy for an acute stress response.
The ability to make predictions from stress hormones about impacts
on individuals and populations exposed to various forms of natural and
anthropogenic stressors relies on understanding the linkages between
changes in stress hormones and resulting physiological impacts.
Currently, the sound characteristics that correlate with specific
stress responses in marine mammals are poorly understood, as are the
ultimate consequences of these changes. Several research efforts have
improved the understanding of, and the ability to predict, how
stressors ultimately affect marine mammal populations (e.g., King et
al., 2015; New et al., 2013a; Pirotta et al., 2015a; Pirotta et al.,
2022b). This includes determining how and to what degree various types
of anthropogenic sound cause stress in marine mammals and understanding
what factors may mitigate those physiological stress responses. Factors
potentially affecting an animal's response to a stressor include life
history, sex, age, reproductive status, overall physiological and
behavioral adaptability, and whether they are na[iuml]ve or experienced
with the sound (e.g., prior experience with a stressor may result in a
reduced response due to habituation) (Finneran and Branstetter, 2013;
St. Aubin and Dierauf, 2001). Because there are many unknowns regarding
the occurrence of acoustically induced stress responses in marine
mammals, any physiological response (e.g., hearing loss or injury) or
significant behavioral response is assumed to be associated with a
stress response.
Non-impulsive sources of sound can cause direct physiological
effects including noise-induced loss of hearing sensitivity (or
``threshold shift'') or other auditory injury, nitrogen decompression,
acoustically-induced bubble growth, and injury due to sound-induced
acoustic resonance. Separately, an animal's behavioral response to an
acoustic exposure might lead to physiological effects that might
ultimately lead to injury or death, which is discussed later in the
Stranding and Mortality section.
Heart Rate Response--
Several experimental studies have measured the heart rate response
of a variety of marine mammals. For example, Miksis et al. (2001)
observed increases in heart rates of captive bottlenose dolphins to
which known calls of other dolphins were played, although no increase
in heart rate was observed when background tank noise was played back.
However, it cannot be determined whether the increase in heart rate was
due to stress or social factors, such as expectation of an encounter
with a known conspecific. Similarly, a young captive beluga's heart
rate increased during exposure to noise, with increases dependent upon
the frequency band of noise and duration of exposure, and with a sharp
decrease to normal or below normal levels upon cessation of the
exposure (Lyamin et al., 2011). Spectral analysis of heart rate
variability corroborated direct measures of heart rate (Bakhchina et
al., 2017). This response might have been in part due to the conditions
during testing, the young age of the animal, and the novelty of the
exposure; a year later the exposure was repeated at a slightly higher
received level and there was no heart rate response, indicating the
beluga whale had potentially habituated to the noise exposure.
Kvadsheim et al. (2010a) measured the heart rate of captive hooded
seals during exposure to sonar signals and found an increase in the
heart rate of the seals during exposure periods versus control periods
when the animals were at the surface. When the animals dove, the normal
dive-related heart rate decrease was not impacted by the sonar
exposure. Similarly, Thompson et al. (1998) observed a rapid, short-
lived decrease in heart rates in wild harbor and grey seals exposed to
seismic air guns (cited in Gordon et al., 2003).
Two captive harbor porpoises showed significant bradycardia
(reduced heart rate), below that which occurs with diving, when they
were exposed to pinger-like sounds with frequencies between 100-140 kHz
(Teilmann et al., 2006). The bradycardia was found only in the early
noise exposures and the porpoises acclimated quickly across

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successive noise exposures. Elmegaard et al. (2021) also found that
initial exposures to sonar sweeps produced bradycardia but did not
elicit a startle response in captive harbor porpoises. As with Teilmann
et al. (2006), the cardiac response disappeared over several repeat
exposures suggesting rapid acclimation to the noise. In the same
animals, 40-kHz noise pulses induced startle responses but without a
change in heart rate. Bakkeren et al. (2023) found no change in the
heart rate of a harbor porpoise during exposure to masking noise (\1/3\
octave band noise, centered frequency of 125 kHz, maximum received
level of 125 dB re 1 [mu]Pa) during an echolocation task but showed
significant bradycardia while blindfolded for the same task. The
authors attributed the change in heart rate to sensory deprivation,
although no strong conclusions about acoustic masking could be made
since the animal was still able to perform the echolocation task in the
presence of the masking noise. Williams et al. (2022) observed periods
of increased heart rate variability in narwhals during seismic air gun
impulse exposure, but profound bradycardia was not noted. Conversely,
Williams et al. (2017) found that a profound bradycardia persisted in
narwhals, even though exercise effort increased dramatically as part of
their escape response following release from capture and handling.
Limited evidence across several different species suggests that
increased heart rate might occur as part of the acute stress response
of marine mammals that are at the surface. However, the decreased heart
rate typical of diving marine mammals can be enhanced in response to an
acute stressor, suggesting that the context of the exposure is critical
to understanding the cardiac response. Furthermore, in instances where
a cardiac response was noted, there appears to be rapid habituation
when repeat exposures occur. Additional research is required to
understand the interaction of dive bradycardia, noise-induced cardiac
responses, and the role of habituation in marine mammals.
Stress Hormone and Immune Response--
What is known about the function of the various stress hormones is
based largely upon observations of the stress response in terrestrial
mammals. The endocrine response of marine mammals to stress may not be
the same as that of terrestrial mammals because of the selective
pressures marine mammals faced during their evolution in an ocean
environment (Atkinson et al., 2015). For example, due to the necessity
of breath-holding while diving and foraging at depth, the physiological
role of epinephrine and norepinephrine (the catecholamines) might be
different in marine versus other mammals.
Catecholamines increase during breath-hold diving in seals, co-
occurring with a reduction in heart rate, peripheral vasoconstriction
(i.e., constriction of blood vessels), and an increased reliance on
anaerobic metabolism during extended dives (Hance et al., 1982;
Hochachka et al., 1995; Hurford et al., 1996); the catecholamine
increase is not associated with increased heart rate, glycemic release,
and increased oxygen consumption typical of terrestrial mammals.
Captive belugas demonstrated no catecholamine response to the playback
of oil drilling sounds (Thomas et al., 1990b) but showed a small but
statistically significant increase in catecholamines following exposure
to impulsive sounds produced from a seismic water gun (Romano et al.,
2004). A captive bottlenose dolphin exposed to the same sounds did not
demonstrate a catecholamine response but did demonstrate a
statistically significant elevation in aldosterone (Romano et al.,
2004); however, the increase was within the normal daily variation
observed in this species (St. Aubin et al., 1996) and was likely of
little biological significance. Aldosterone has been speculated to not
only contribute to electrolyte balance, but possibly also the
maintenance of blood pressure during periods of vasoconstriction
(Houser et al., 2011). In marine mammals, aldosterone is thought to
play a role in mediating stress (St. Aubin and Dierauf, 2001; St. Aubin
and Geraci, 1989).
Yang et al. (2021) measured cortisol concentrations in two captive
bottlenose dolphins and found significantly higher concentrations after
exposure to 140 dB re 1 [mu]Pa impulsive noise playbacks. Two out of
six tested indicators of immune system function underwent acoustic
dose-dependent changes, suggesting that repeated exposures or sustained
stress response to impulsive sounds may increase an affected
individual's susceptibility to pathogens. Unfortunately, absolute
values of cortisol were not provided, and it is not possible from the
study to tell if cortisol rose to problematic levels (e.g., see normal
variation and changes due to handling in Houser et al. (2021) and
Champagne et al. (2018)). Exposing dolphins to a different acoustic
stressor yielded contrasting results. Houser et al. (2020) measured
cortisol and epinephrine obtained from 30 captive bottlenose dolphins
exposed to simulated Navy MFAS and found no correlation between SPL and
stress hormone levels, even though sound exposures were as high as 185
dB re 1 [mu]Pa. In the same experiment (Houser et al., 2013b),
behavioral responses were shown to increase in severity with increasing
received SPLs. These results suggest that behavioral responses to sonar
signals are not necessarily indicative of a hormonal stress response.
Whereas a limited amount of work has addressed the potential for
acute sound exposures to produce a stress response, almost nothing is
known about how chronic exposure to acoustic stressors affects stress
hormones in marine mammals, particularly as it relates to survival or
reproduction. In what is probably the only study of chronic noise
exposure in marine mammals associating changes in a stress hormone with
changes in anthropogenic noise, Rolland et al. (2012) compared the
levels of cortisol metabolites in NARW feces collected before and after
September 11, 2001. Following the events of September 11, 2001,
shipping was significantly reduced in the region where fecal
collections were made, and regional ocean background noise declined.
Fecal cortisol metabolites significantly decreased during the period of
reduced ship traffic and ocean noise (Rolland et al., 2012). Rolland et
al. (2017) also compared acute (death by vessel strike) to chronic
(entanglement or live stranding) stressors in NARW and found that
whales subject to chronic stressors had higher levels of glucocorticoid
stress hormones (cortisol and corticosterone) than either healthy
whales or those killed by ships. It was presumed that whales subjected
to acute stress may have died too quickly for increases in fecal
glucocorticoids to be detected.
Considerably more work has been conducted in an attempt to
determine the potential effect of vessel disturbance on smaller
cetaceans, particularly killer whales (Bain, 2002; Erbe, 2002; Lusseau,
2006; Noren et al., 2009; Pirotta et al., 2015b; Read et al., 2014;
Rolland et al., 2012; Williams et al., 2009; Williams et al., 2014a;
Williams et al., 2014b; Williams et al., 2006b). Most of these efforts
focused primarily on estimates of metabolic costs associated with
altered behavior or inferred consequences of boat presence and noise
but did not directly measure stress hormones. However, Ayres et al.
(2012) investigated Southern Resident killer whale fecal thyroid
hormone and cortisol metabolites to assess two potential threats to the
species'

[[Page 32191]]

recovery: lack of prey (salmon) and impacts from exposure to the
physical presence of vessel traffic (but without measuring vessel
traffic noise). Ayres et al. (2012) concluded from these stress hormone
measures that the lack of prey overshadowed any population-level
physiological impacts on Southern Resident killer whales due to vessel
traffic. Lemos et al. (2022) investigated the potential for vessel
traffic to affect gray whales. By assessing gray whale fecal cortisol
metabolites across years in which vessel traffic was variable, Lemos et
al. (2022) found a direct relationship between the presence/density of
vessel traffic and fecal cortisol metabolite levels. Unfortunately, no
direct noise exposure measurements were made on any individual making
it impossible to tell if other natural and anthropogenic factors could
also be related to the results. Collectively, these studies indicate
the difficulty in determining which factors are primarily influence the
secretion of stress hormones, including the separate and additive
effects of vessel presence and vessel noise. While vessel presence
could contribute to the variation in fecal cortisol metabolites in
North Atlantic right whales and gray whales, there are other potential
influences on fecal hormone metabolites, so it is difficult to
establish a direct link between ocean noise and fecal hormone
metabolites.
Non-Auditory Injury
Non-auditory injury, or direct injury, is considered less likely to
occur in the context of the Action Proponents' activities than auditory
injury and the primary anticipated source of non-auditory injury for
these activities is exposure to the pressure generated by explosive
detonations, which is discussed in the Potential Effects of Explosive
Sources on Marine Mammals section below. Here, we discuss less direct
non-auditory injury impacts, including acoustically induced bubble
formation, injury from sonar-induced acoustic resonance, and
behaviorally mediated injury.
One theoretical cause of injury to marine mammals is rectified
diffusion (Crum and Mao, 1996), the process of increasing the size of a
bubble by exposing it to a sound field. This process could be
facilitated if the environment in which the ensonified bubbles exist is
supersaturated with gas. Repetitive diving by marine mammals can cause
the blood and some tissues to accumulate gas to a greater degree than
is supported by the surrounding environmental pressure (Ridgway and
Howard, 1979). The deeper and longer dives of some marine mammals (for
example, beaked whales) are theoretically predicted to induce greater
supersaturation (Houser et al., 2001b). If rectified diffusion were
possible in marine mammals exposed to high-level sound, conditions of
tissue supersaturation could theoretically speed the rate and increase
the size of bubble growth. Subsequent effects due to tissue trauma and
emboli would presumably mirror those observed in humans suffering from
decompression sickness. Acoustically-induced (or mediated) bubble
growth and other pressure-related physiological impacts are addressed
below but are not expected to result from the Action Proponents'
proposed activities.
It is unlikely that the short duration (in combination with the
source levels) of sonar pings would be long enough to drive bubble
growth to any substantial size, if such a phenomenon occurs. However,
an alternative but related hypothesis has also been suggested: stable
bubbles could be destabilized by high-level sound exposures such that
bubble growth then occurs through static diffusion of gas out of the
tissues. In such a scenario the marine mammal would need to be in a
gas-supersaturated state for a long enough period of time for bubbles
to become of a problematic size. Recent research with ex vivo
supersaturated bovine tissues suggested that, for a 37 kHz signal, a
sound exposure of approximately 215 dB re 1 [mu]Pa would be required
before microbubbles became destabilized and grew (Crum et al., 2005).
Assuming spherical spreading loss and a nominal sonar source level of
235 dB re 1 [mu]Pa at 1 m, a whale would need to be within 33 ft (10 m)
of the sonar dome to be exposed to such sound levels. Furthermore,
tissues in the study were supersaturated by exposing them to pressures
of 400-700 kilopascals for periods of hours and then releasing them to
ambient pressures. Assuming the equilibration of gases with the tissues
occurred when the tissues were exposed to the high pressures, levels of
supersaturation in the tissues could have been as high as 400-700
percent. These levels of tissue supersaturation are substantially
higher than model predictions for marine mammals (Fahlman et al., 2009;
Fahlman et al., 2014; Houser et al., 2001; Saunders et al., 2008). It
is improbable that this mechanism is responsible for stranding events
or traumas associated with beaked whale strandings because both the
degree of supersaturation and exposure levels observed to cause
microbubble destabilization are unlikely to occur, either alone or in
concert.
Yet another hypothesis has speculated that rapid ascent to the
surface following exposure to a startling sound might produce tissue
gas saturation sufficient for the evolution of nitrogen bubbles (i.e.,
decompression sickness) (Jepson et al., 2003; Fernandez et al., 2005).
In this scenario, the rate of ascent would need to be sufficiently
rapid to compromise behavioral or physiological protections against
nitrogen bubble formation. Alternatively, Tyack et al. (2006) studied
the deep diving behavior of beaked whales and concluded that: ``Using
current models of breath-hold diving, we infer that their natural
diving behavior is inconsistent with known problems of acute nitrogen
supersaturation and embolism.'' Collectively, these hypotheses can be
referred to as ``hypotheses of acoustically mediated bubble growth.''
Although theoretical predictions suggest the possibility for
acoustically mediated bubble growth, there is considerable disagreement
among scientists as to its likelihood (Piantadosi and Thalmann, 2004;
Evans and Miller, 2003; Cox et al., 2006; Rommel et al., 2006). Crum
and Mao (1996) hypothesized that received levels would have to exceed
190 dB in order for there to be the possibility of significant bubble
growth due to supersaturation of gases in the blood (i.e., rectified
diffusion). Work conducted by Crum et al. (2005) demonstrated the
possibility of rectified diffusion for short duration signals, but at
SELs and tissue saturation levels that are highly improbable to occur
in diving marine mammals. To date, energy levels predicted to cause in
vivo bubble formation within diving cetaceans have not been evaluated
(NOAA, 2002b). Jepson et al. (2003, 2005) and Fernandez et al. (2004,
2005) concluded that in vivo bubble formation, which may be exacerbated
by deep, long-duration, repetitive dives may explain why beaked whales
appear to be relatively vulnerable to MFAS/HFAS exposures. It has also
been argued that traumas from some beaked whale strandings are
consistent with gas emboli and bubble-induced tissue separations
(Jepson et al., 2003); however, there is no conclusive evidence of this
(Rommel et al., 2006). Based on examination of sonar-associated
strandings, Bernaldo de Quiros et al. (2019) list diagnostic features,
the presence of all of which suggest gas and fat embolic syndrome for
beaked whales stranded in association with sonar exposure.
As described in additional detail in the Behaviorally Mediated
Injury section of appendix D the 2024 HCTT Draft EIS/OEIS, marine
mammals

[[Page 32192]]

generally are thought to deal with nitrogen loads in their blood and
other tissues, caused by gas exchange from the lungs under conditions
of high ambient pressure during diving, through anatomical, behavioral,
and physiological adaptations (Hooker et al., 2012). Although not a
direct injury, variations in marine mammal diving behavior or avoidance
responses have been hypothesized to result in nitrogen off-gassing in
super-saturated tissues, possibly to the point of deleterious vascular
and tissue bubble formation (Hooker et al., 2012; Jepson et al., 2003;
Saunders et al., 2008) with resulting symptoms similar to decompression
sickness, however the process is still not well understood.
In 2009, Hooker et al. tested two mathematical models to predict
blood and tissue tension N2 (PN2) using field data from
three beaked whale species: northern bottlenose whales, goose-beaked
whales, and Blainville's beaked whales. The researchers aimed to
determine if physiology (body mass, diving lung volume, and dive
response) or dive behavior (dive depth and duration, changes in ascent
rate, and diel behavior) would lead to differences in PN2
levels and thereby decompression sickness risk between species. In
their study, they compared results for previously published time depth
recorder data (Hooker and Baird, 1999; Baird et al., 2006, 2008) from
goose-beaked whale, Blainville's beaked whale, and northern bottlenose
whale. They reported that diving lung volume and extent of the dive
response had a large effect on end-dive PN2. Also, results
showed that dive profiles had a larger influence on end-dive
PN2 than body mass differences between species. Despite diel
changes (i.e., variation that occurs regularly every day or most days)
in dive behavior, PN2 levels showed no consistent trend.
Model output suggested that all three species live with tissue
PN2 levels that would cause a significant proportion of
decompression sickness cases in terrestrial mammals. The authors
concluded that the dive behavior of goose-beaked whale was different
from both Blainville's beaked whale and northern bottlenose whale and
resulted in higher predicted tissue and blood N2 levels (Hooker et al.,
2009). They also suggested that the prevalence of goose-beaked whales
stranding after naval sonar exercises could be explained by either a
higher abundance of this species in the affected areas or by possible
species differences in behavior and/or physiology related to MF active
sonar (Hooker et al., 2009).
Bernaldo de Quiros et al. (2012) showed that, among stranded
whales, deep diving species of whales had higher abundances of gas
bubbles compared to shallow diving species. Kvadsheim et al. (2012)
estimated blood and tissue PN2 levels in species
representing shallow, intermediate, and deep diving cetaceans following
behavioral responses to sonar and their comparisons found that deep
diving species had higher end-dive blood and tissue N2 levels,
indicating a higher risk of developing gas bubble emboli compared with
shallow diving species. Fahlmann et al. (2014) evaluated dive data
recorded from sperm, killer, long-finned pilot, Blainville's, and
goose-beaked whales before and during exposure to low-frequency (1-2
kHz), as defined by the authors, and mid-frequency (2-7 kHz) active
sonar in an attempt to determine if either differences in dive behavior
or physiological responses to sonar are plausible risk factors for
bubble formation. The authors suggested that CO2 may
initiate bubble formation and growth, while elevated levels of N2 may
be important for continued bubble growth. The authors also suggest that
if CO2 plays an important role in bubble formation, a
cetacean escaping a sound source may experience increased metabolic
rate, CO2 production, and alteration in cardiac output,
which could increase risk of gas bubble emboli. However, as discussed
in Kvadsheim et al. (2012), the actual observed behavioral responses to
sonar from the species in their study (sperm, killer, long-finned
pilot, Blainville's beaked, and goose-beaked whales) did not imply any
significantly increased risk of decompression sickness due to high
levels of N2. Therefore, further information is needed to understand
the relationship between exposure to stimuli, behavioral response
(discussed in more detail below), elevated N2 levels, and gas bubble
emboli in marine mammals. The hypotheses for gas bubble formation
related to beaked whale strandings is that beaked whales potentially
have strong avoidance responses to MFAS because they sound similar to
their main predator, the killer whale (Cox et al., 2006; Southall et
al., 2007; Zimmer and Tyack, 2007; Baird et al., 2008; Hooker et al.,
2009). Further investigation is needed to assess the potential validity
of these hypotheses.
To summarize, while there are several hypotheses, there is little
data directly connecting intense, anthropogenic underwater sounds with
non-auditory physical effects in marine mammals. The available data do
not support identification of a specific exposure level above which
non-auditory effects can be expected (Southall et al., 2007) or any
meaningful quantitative predictions of the numbers (if any) of marine
mammals that might be affected in these ways. In addition, such
effects, if they occur at all, would be expected to be limited to
situations where marine mammals were exposed to high powered sounds at
very close range over a prolonged period of time, which is not expected
to occur based on the speed of the vessels operating sonar in
combination with the speed and behavior of marine mammals in the
vicinity of sonar.
An object exposed to its resonant frequency will tend to amplify
its vibration at that frequency, a phenomenon called acoustic
resonance. Acoustic resonance has been proposed as a potential
mechanism by which a sonar or sources with similar operating
characteristics could damage tissues of marine mammals. In 2002, NMFS
convened a panel of government and private scientists to investigate
the potential for acoustic resonance to occur in marine mammals (NOAA,
2002). They modeled and evaluated the likelihood that Navy MFAS (2-10
kHz) caused resonance effects in beaked whales that eventually led to
their stranding. The workshop participants concluded that resonance in
air-filled structures was not likely to have played a primary role in
the Bahamas stranding in 2000. They listed several reasons supporting
this finding including (among others): tissue displacements at
resonance are estimated to be too small to cause tissue damage; tissue-
lined air spaces most susceptible to resonance are too large in marine
mammals to have resonant frequencies in the ranges used by MFAS or
LFAS; lung resonant frequencies increase with depth, and tissue
displacements decrease with depth so if resonance is more likely to be
caused at depth it is also less likely to have an affect there; and
lung tissue damage has not been observed in any mass, multi-species
stranding of beaked whales. The frequency at which resonance was
predicted to occur in the animals' lungs was 50 Hz, well below the
frequencies used by the MFAS systems associated with the Bahamas event.
The workshop participants focused on the March 2000 stranding of beaked
whales in the Bahamas as high-quality data were available, but the
workshop report notes that the results apply to other sonar-related
stranding events. For the reasons given by the 2002 workshop
participants, we do not anticipate injury due to sonar-induced acoustic
resonance from the Action Proponents' proposed activity.

[[Page 32193]]

Potential Effects of Explosive Sources on Marine Mammals

Explosive detonations that occur in water send a shock wave and
sound energy through the water and can release gaseous by-products,
create an oscillating bubble, or cause a plume of water to shoot up
from the water surface. The shock wave and accompanying noise are of
most concern to marine animals and the potential effects of an
explosive injury to marine mammals would consist of primary blast
injury, which refers to injuries resulting from the compression of a
body exposed to a blast wave. Blast effects are greatest at the gas-
liquid interface (Landsberg, 2000) and are usually observed as
barotrauma of gas-containing structures (e.g., lung, gastrointestinal
tract) and structural damage to the auditory system (Goertner, 1982;
Greaves et al., 1943; Hill, 1978; Office of the Surgeon General, 1991;
Richmond et al., 1973; Yelverton et al., 1973). Depending on the
intensity of the shock wave and size, location, and depth of the
animal, an animal can be injured, killed, suffer non-lethal physical
effects, experience hearing related effects with or without behavioral
responses, or exhibit temporary behavioral responses or tolerance from
hearing the blast sound. Generally, exposures to higher levels of
impulse and pressure levels would result in greater impacts to an
individual animal.
The near instantaneous high magnitude pressure change near an
explosion can injure an animal where tissue material properties
significantly differ from the surrounding environment, such as around
air-filled cavities in the lungs or gastrointestinal tract. Large
pressure changes at tissue-air interfaces in the lungs and
gastrointestinal tract may cause tissue rupture, resulting in a range
of injuries depending on degree of exposure. The lungs are typically
the first site to show any damage, while the solid organs (e.g., liver,
spleen, and kidney) are more resistant to blast injury (Clark and Ward,
1943). Odontocetes can also incur hemorrhaging in the acoustic fats in
the melon and jaw (Siebert et al., 2022). Recoverable injuries would
include slight lung injury, such as capillary interstitial bleeding,
and contusions to the gastrointestinal tract. More severe injuries,
such as tissue lacerations, major hemorrhage, organ rupture, or air in
the chest cavity (pneumothorax), would significantly reduce fitness and
likely cause death in the wild. Rupture of the lung may also introduce
air into the vascular system, producing air emboli that can cause a
stroke or heart attack by restricting oxygen delivery to critical
organs.
Injuries resulting from a shock wave take place at boundaries
between tissues of different densities. Different velocities are
imparted to tissues of different densities, and this can lead to their
physical disruption. Intestinal walls can bruise or rupture, with
subsequent hemorrhage and escape of gut contents into the body cavity.
Less severe gastrointestinal tract injuries include contusions,
petechiae (i.e., small red or purple spots caused by bleeding in the
skin), and slight hemorrhaging (Yelverton et al., 1973).
Relatively little is known about auditory system trauma in marine
mammals resulting from explosive exposure, although it is assumed that
auditory structures would be vulnerable to blast injuries because the
ears are the most sensitive to pressure and, therefore, they are the
organs most sensitive to injury (Ketten, 2000). Sound-related damage
associated with sound energy from detonations can be theoretically
distinct from injury from the shock wave, particularly farther from the
explosion. If a noise is audible to an animal, it has the potential to
damage the animal's hearing by causing decreased sensitivity (Ketten,
1995). Lethal impacts are those that result in immediate death or
serious debilitation in or near an intense source and are not,
technically, pure acoustic trauma (Ketten, 1995). Sublethal impacts
include hearing loss, which is caused by exposures to perceptible
sounds. Severe damage (from the shock wave) to the ears includes
tympanic membrane rupture, fracture of the ossicles, damage to the
cochlea, hemorrhage, and cerebrospinal fluid leakage into the middle
ear. Moderate injury implies partial hearing loss due to tympanic
membrane rupture and blood in the middle ear. Permanent hearing loss
also can occur when the hair cells are damaged by one very loud event,
as well as by prolonged exposure to a loud noise or chronic exposure to
noise. The level of impact from blasts depends on both an animal's
location and, at outer zones, on its sensitivity to the residual noise
(Ketten, 1995). Auditory trauma was found in 2 humpback whales that
died after the detonation of an 11,023 lb (5,000 kg) explosive used off
Newfoundland during demolition of an offshore oil rig platform (Ketten
et al., 1993), but the proximity of the whales to the detonation was
unknown. Eardrum rupture was examined in submerged terrestrial mammals
exposed to underwater explosions (Richmond et al., 1973; Yelverton et
al., 1973); however, results may not be applicable to the anatomical
adaptations for underwater hearing in marine mammals given differences
in impedance (Wartzok and Ketten 1999).
In general, models predict that an animal would be less susceptible
to injury near the water surface because the pressure wave reflected
from the water surface would interfere with the direct path pressure
wave, reducing positive pressure exposure (Goertner, 1982; Yelverton
and Richmond, 1981). This is shown in the records of humans exposed to
blast while in the water, which show that the gastrointestinal tract
was more likely to be injured than the lungs, likely due to the
shallower exposure geometry of the lungs (i.e., closer to the water
surface) (Lance et al., 2015). Susceptibility would increase with
depth, until normal lung collapse (due to increasing hydrostatic
pressure) and increasing ambient pressures again reduce susceptibility
(Goertner, 1982). The only known occurrence of mortality or injury to a
marine mammal due to a Navy training event involving explosives
occurred in March 2011 in nearshore waters off San Diego, California,
at the Silver Strand Training Complex (see Strandings Associated with
Explosive Use section below).
Controlled tests with a variety of lab animals (i.e., mice, rats,
dogs, pigs, sheep, and other species) are the best data sources on
actual injury to mammals due to underwater exposure to explosions. In
the early 1970s, the Lovelace Foundation for Medical Education and
Research conducted a series of tests in an artificial pond at Kirtland
Air Force Base, New Mexico, to determine the effects of underwater
explosions on mammals, with the goal of determining safe ranges for
human divers. The resulting data were summarized in two reports
(Richmond et al., 1973; Yelverton et al., 1973). Specific physiological
observations for each test animal are documented in Richmond et al.
(1973). Gas-containing internal organs, such as lungs and intestines,
were the principle damage sites in submerged terrestrial mammals; this
is consistent with earlier studies of mammal exposures to underwater
explosions in which lungs were consistently the first areas to show
damage, with less consistent damage observed in the gastrointestinal
tract (Clark and Ward, 1943; Greaves et al., 1943).
In the Lovelace studies, the first positive acoustic impulse was
found to be the metric most related to degree of injury, and size of an
animal's gas-containing cavities was thought to play a role in blast
injury susceptibility. For

[[Page 32194]]

these shallow exposures of small terrestrial mammals (masses ranging
from 3.4 to 50 kg) to underwater detonations, Richmond et al. (1973)
reported that no blast injuries were observed when exposures were less
than 6 pounds per square inch per millisecond (psi-ms) (40 pascal
seconds (Pa-s)), no instances of slight lung hemorrhage occurred below
20 psi-ms (140 Pa-s), and instances of no lung damage were observed in
some exposures at higher levels up to 40 psi-ms (280 Pa-s). An impulse
of 34 psi-ms (230 Pa-s) resulted in about 50 percent incidence of
slight lung hemorrhage. About half of the animals had gastrointestinal
tract contusions (with slight ulceration, i.e., some perforation of the
mucosal layer) at exposures of 25-27 psi-ms (170-190 Pa-s). Lung
injuries were found to be slightly more prevalent than gastrointestinal
tract injuries for the same exposure. The anatomical differences
between the terrestrial animals used in the Lovelace tests and marine
mammals are summarized in Fetherston et al. (2019). Goertner (1982)
examined how lung cavity size would affect susceptibility to blast
injury by considering both marine mammal size and depth in a bubble
oscillation model of the lung; however, the Goertner (1982) model did
not consider how tissues surrounding the respiratory air spaces would
reflect shock wave energy or constrain oscillation (Fetherston et al.,
2019).
Goertner (1982) suggested a peak overpressure gastrointestinal
tract injury criterion because the size of gas bubbles in the
gastrointestinal tract are variable, and their oscillation period could
be short relative to primary blast wave exposure duration. The
potential for gastrointestinal tract injury, therefore, may not be
adequately modeled by the single oscillation bubble methodology used to
estimate lung injury due to impulse. Like impulse, however, high
instantaneous pressures may damage many parts of the body, but damage
to the gastrointestinal tract is used as an indicator of any peak
pressure-induced injury due to its vulnerability.
Because gas-containing organs are more vulnerable to primary blast
injury, adaptations for diving that allow for collapse of lung tissues
with depth may make animals less vulnerable to lung injury with depth.
Adaptations for diving include a flexible thoracic cavity, distensible
veins that can fill space as air compresses, elastic lung tissue, and
resilient tracheas with interlocking cartilaginous rings that provide
strength and flexibility (Ridgway, 1972). Denk et al. (2020) found
intra-species differences in the compliance of tracheobronchial
structures of post-mortem cetaceans and pinnipeds under diving
hydrostatic pressures, which would affect depth of alveolar collapse.
Older literature suggested complete lung collapse depths at
approximately 229.7 ft (70 m) for dolphins (Ridgway and Howard, 1979)
and 65.6 to 164 ft (20 to 50 m) for phocid seals (Falke et al., 1985;
Kooyman et al., 1972). Follow-on work by Kooyman and Sinnett (1982), in
which pulmonary shunting was studied in harbor seals and sea lions,
suggested that complete lung collapse for these species would be about
557.7 ft (170 m) and about 590.6 (180 m), respectively. Evidence in sea
lions suggests that complete collapse might not occur until depths as
great as 738.2 ft (225 m); although the depth of collapse and depth of
the dive are related, sea lions can affect the depth of lung collapse
by varying the amount of air inhaled on a dive (McDonald and Ponganis,
2012). This is an important consideration for all divers who can
modulate lung volume and gas exchange prior to diving via the degree of
inhalation and during diving via exhalation (Fahlman et al., 2009);
indeed, there are noted differences in pre-dive respiratory behavior,
with some marine mammals exhibiting pre-dive exhalation to reduce the
lung volume (e.g., phocid seals) (Kooyman et al., 1973).

Further Potential Effects of Behavioral Disturbance on Marine Mammal
Fitness

The different ways in which marine mammals respond to sound are
sometimes indicators of the ultimate effect that exposure to a given
stimulus will have on the well-being (survival, reproduction, etc.) of
an animal. The long-term consequences of disturbance, hearing loss,
chronic masking, and acute or chronic physiological stress are
difficult to predict because of the different factors experienced by
individual animals, such as context of stressor exposure, underlying
health conditions, and other environmental or anthropogenic stressors.
Linking these non-lethal effects on individuals to changes in
population growth rates requires long-term data, which is lacking for
many populations. We summarize several studies below, but there are few
quantitative marine mammal data relating the exposure of marine mammals
to sound to effects on reproduction or survival, though data exists for
terrestrial species to which we can draw comparisons for marine
mammals. Several authors have reported that disturbance stimuli may
cause animals to abandon nesting and foraging sites (Sutherland and
Crockford, 1993); may cause animals to increase their activity levels
and suffer premature deaths or reduced reproductive success when their
energy expenditures exceed their energy budgets (Daan et al., 1996;
Feare, 1976; Mullner et al., 2004); or may cause animals to experience
higher predation rates when they adopt risk-prone foraging or migratory
strategies (Frid and Dill, 2002). Each of these studies addressed the
consequences of animals shifting from one behavioral state (e.g.,
resting or foraging) to another behavioral state (e.g., avoidance or
escape behavior) because of human disturbance or disturbance stimuli.
Lusseau and Bejder (2007) present data from three long-term studies
illustrating the connections between disturbance from whale-watching
boats and population-level effects in cetaceans. In Shark Bay
Australia, the abundance of bottlenose dolphins was compared within
adjacent control and tourism sites over three consecutive 4.5-year
periods of increasing tourism levels. Between the second and third time
periods, in which tourism doubled, dolphin abundance decreased by 15
percent in the tourism area and did not change significantly in the
control area. In Fiordland, New Zealand, two populations (Milford and
Doubtful Sounds) of bottlenose dolphins with tourism levels that
differed by a factor of seven were observed and significant increases
in travelling time and decreases in resting time were documented for
both. Consistent short-term avoidance strategies were observed in
response to tour boats until a threshold of disturbance was reached
(average 68 minutes between interactions), after which the response
switched to a longer-term habitat displacement strategy. For one
population, tourism only occurred in a part of the home range. However,
tourism occurred throughout the home range of the Doubtful Sound
population and once boat traffic increased beyond the 68-minute
threshold (resulting in abandonment of their home range/preferred
habitat), reproductive success drastically decreased (i.e., increased
stillbirths) and abundance decreased significantly (from 67 to 56
individuals in a short period). Last, in a study of Northern Resident
killer whales off Vancouver Island, exposure to boat traffic was shown
to reduce foraging opportunities and increase traveling time. A simple
bioenergetics model was applied to show that the reduced foraging
opportunities equated to a decreased energy intake of 18 percent, while
the increased traveling incurred

[[Page 32195]]

an increased energy output of 3-4 percent, which suggests that a
management action based on avoiding interference with foraging might be
particularly effective.
An important variable to consider is duration of disturbance.
Severity scales used to assess behavioral responses of marine mammals
to acute sound exposures are not appropriate to apply to sustained or
chronic exposures, which requires considering the health of a
population over time rather than a focus on immediate impacts to
individuals (Southall et al., 2021). For example, short-term costs
experienced over the course of a week by an otherwise healthy
individual may be recouped over time after exposure to the stressor
ends. These short-term costs would be unlikely to result in long-term
consequences to that individual or to that individual's population.
Comparatively, long-term costs accumulated by otherwise healthy
individuals over an entire season, year, or throughout a life stage
(e.g., pup, juvenile, adult) would be less easily recouped and more
likely to result in long-term consequences to that individual or
population.
Marine mammals exposed to frequent or intense anthropogenic
activities may leave the area, habituate to the activity, or tolerate
the disturbance and remain in the area (Wartzok et al., 2003). Highly
resident or localized populations may also stay in an area of
disturbance because the cost of displacement is higher than the cost of
remaining in the area (Forney et al., 2017). As such, an apparent lack
of response (e.g., no displacement or avoidance of a sound source) does
not necessarily indicate there is no cost to the individual or
population, as some resources or habitats may be of such high value
that animals may choose to stay, even when experiencing the
consequences of stress, masking, or hearing loss (Forney et al., 2017).
Longer term displacement can lead to changes in abundance or
distribution patterns of the species in the affected region (Bejder et
al., 2006b; Blackwell et al., 2004; Teilmann et al., 2006). For
example, gray whales in Baja California, Mexico, abandoned a historical
breeding lagoon in the mid-1960s due to an increase in dredging and
commercial shipping operations, and only repopulated the lagoon after
shipping activities had ceased for several years (Bryant et al., 1984).
Mysticetes in the northeast tended to adjust to vessel traffic over
several years, trending towards more neutral behavioral responses to
passing vessels (Watkins, 1986), indicating that some animals may
habituate to high levels of human activity. A study on bottlenose
dolphin responses to vessel approaches found that lesser responses in
populations of dolphins regularly subjected to high levels of vessel
traffic could be a sign of habituation, or it could be that the more
sensitive animals in this population previously abandoned the area of
higher human activity (Bejder et al., 2006a).
Population characteristics (e.g., whether a population is open or
closed to immigration and emigration) can influence sensitivity to
disturbance as well; closed populations could not withstand a higher
probability of disturbance compared to open populations with no
limitation on food (New et al., 2020). Predicting population trends or
long-term displacement patterns due to anthropogenic disturbance is
challenging due to limited information and survey data for many species
over sufficient spatiotemporal scales, as well as a full understanding
of how other factors, such as oceanographic oscillations, affect marine
mammal presence (Moore and Barlow, 2013; Barlow, 2016; Moore and
Barlow, 2017).
Population models are necessary to understand and link short-term
effects to individuals from disturbance (anthropogenic impacts or
environmental change) to long-term population consequences. Population
models require inputs for the population size and changes in vital
rates of the population (e.g., the mean values for survival age,
lifetime reproductive success, recruitment of new individuals into the
population), to predict changes in population dynamics (e.g.,
population growth rate). These efforts often rely on bioenergetic
models, or energy budget models, which analyze energy intake from food
and energy costs for life functions, such as maintenance, growth, and
reproduction, either at the individual or population level (Pirotta,
2022), and model sensitivity analyses have identified the most
consequential parameters, including prey characteristics, feeding
processes, energy expenditure, body size, energy storage, and lactation
capability (Pirotta, 2022). However, there is a high level of
uncertainty around many parameters in these models (H[uuml]tt et al.,
2023).
The U.S. National Research Council (NRC) committee on
Characterizing Biologically Significant Marine Mammal Behavior
developed an initial conceptual model to link acoustic disturbance to
population effects and inform data and research needs (NRC, 2005). This
Population Consequences of Acoustic Disturbance, or PCAD, conceptual
model linked the parameters of sound exposure, behavior change, life
function immediately affected, vital rates, and population effects. In
its report, the committee found that the relationships between vital
rates and population effects were relatively well understood, but that
the relationships between the other components of the model were not
well-known or easily observed.
Following the PCAD framework (NRC, 2005), an ONR working group
developed the Potential Consequences of Disturbance (PCoD), outlining
an updated conceptual model of the relationships linking disturbance to
changes in behavior and physiology, health, vital rates, and population
dynamics. The PCoD model considers all types of disturbance, not solely
anthropogenic or acoustic, and incorporates physiological changes, such
as stress or injury, along with behavioral changes as a direct result
of disturbance (National Academies of Sciences Engineering and
Medicine, 2017). In this framework, behavioral and physiological
changes can have direct (acute) effects on vital rates, such as when
changes in habitat use or increased stress levels raise the probability
of mother-calf separation or predation; they can have indirect and
long-term (chronic) effects on vital rates, such as when changes in
time/energy budgets or increased disease susceptibility affect health,
which then affects vital rates; or they can have no effect to vital
rates (New et al., 2014; Pirotta et al., 2018a). In addition to
outlining this general framework and compiling the relevant literature
that supports it, the authors chose four example species for which
extensive long-term monitoring data exist (southern elephant seals,
North Atlantic right whale, Ziphiidae beaked whales, and bottlenose
dolphins) and developed state-space energetic models that can be used
to forecast longer-term, population-level impacts from behavioral
changes. While these models cannot yet be applied broadly to project-
specific risk assessments for the majority of species, as well as
requiring significant resources and time to conduct (more than is
typically available to support regulatory compliance for one project),
they are a critical first step towards being able to quantify the
likelihood of a population level effect. Since New et al. (2014),
several publications have described models developed to examine the
long-term effects of environmental or anthropogenic disturbance of
foraging on various life stages of selected species

[[Page 32196]]

(sperm whale, Farmer et al. (2018); California sea lion, McHuron et al.
(2018); and blue whale, Pirotta, et al. (2018a)).
The PCoD model identifies the types of data that would be needed to
assess population-level impacts. These data are lacking for many marine
mammal species (Booth et al., 2020). Southall et al. (2021) states that
future modeling and population simulation studies can help determine
population-wide long-term consequences and impact analysis. However,
the method to do so is still developing, as there are gaps in the
literature, possible sampling biases, and results are rarely ground-
truthed, with a few exceptions (Booth et al., 2022; Schwarz et al.,
2022). Nowacek et al. (2016) reviewed technologies such as passive
acoustic monitoring, tagging, and the use of unmanned aerial vehicles
which can improve scientists' abilities to study these model inputs and
link behavioral changes to individual life functions and ultimately
population-level effects. Relevant data needed for improving analyses
of population-level consequences resulting from disturbances will
continue to be collected during the 7-year period of the LOAs through
projects funded by the Navy's Marine Species Monitoring Program.
Multiple case studies across marine mammal taxonomic groups have been
conducted following the PCoD framework. From these studies, Keen et al.
(2021) identified themes and contextual factors relevant to assessing
impacts to populations due to disturbance, which have been considered
in the context of the impacts of the Action Proponents' activities.
A population's movement ecology determines the potential for
spatiotemporal overlap with a disturbance. Resident populations or
populations that rely on spatially limited habitats for critical life
functions (i.e., foraging, breeding) would be at greater risk of
repeated or chronic exposure to disturbances than populations that are
wide-ranging relative to the footprint of a disturbance (Keen et al.,
2021). Even for the same species, differences in habitat use between
populations can result in different potential for repeated exposure to
individuals for a similar stressor (Costa et al., 2016a). The location
and radius of disturbance can impact how many animals are exposed and
for how long (Costa et al., 2016b). While some models have shown the
advantages of populations with larger ranges, namely the decreased
chance of being exposed (Costa et al., 2016b), it's important to
consider that for some species, the energetic cost of a longer
migration could make a population more sensitive to energy lost through
disturbance (Villegas-Amtmann et al., 2017). In addition to ranging
patterns, a species' activity budgets and lunging rates can cause
variability in their predicted cost of disturbance as well (Pirotta et
al., 2021).
Bioenergetics frameworks that examine the impact of foraging
disruption on body reserves of individual whales found that rates of
daily foraging disruption can predict the number of days to terminal
starvation for various life stages (Farmer et al., 2018b). Similarly,
when a population is displaced by a stressor, and only has access to
areas of poor habitat quality (i.e., low prey abundance) for
relocation, bioenergetic models may be more likely to predict
starvation, longer recovery times, or extinction (Hin et al., 2023).
There is some debate over the use of blubber thickness as a metric of
cetacean energy stores and health, as marine mammals may not use their
fat stores in a similar manner to terrestrial mammals (Derous et al.,
2020).
Resource limitation can impact marine mammal population growth rate
regardless of additional anthropogenic disturbance. Stochastic Dynamic
Programming models have been used to explore the impact declining prey
species has on focal marine mammal predators (McHuron et al., 2023a;
McHuron et al., 2023b). A Stochastic Dynamic Programming model
determined that a decrease in walleye pollock (Gadus chalcogrammus)
availability increased the time and distance northern fur seal mothers
had to travel offshore, which negatively impacted pup growth rate and
wean mass, despite attempts to compensate with longer recovery time on
land (McHuron et al., 2023b). Prey is an important factor in long-term
consequence models for many species of marine mammals. In disturbance
models that predict habitat displacement or otherwise reduced foraging
opportunities, populations are being deprived of energy dense prey or
``high quality'' areas which can lead to long-term impacts on fecundity
and survival (Czapanskiy et al., 2021; Hin et al., 2019; McHuron et
al., 2023a; New et al., 2013b). Prey density limits the energy
available for growth, reproduction, and survival. Some disturbance
models indicate that the immediate decrease in a portion of the
population (e.g., young lactating mothers) is not necessarily
detrimental to a population, since as a result, prey availability
increases and the population's overall improved body condition reduces
the age at first calf (Hin et al., 2021). The timing of a disturbance
with seasonally available resources is also important; if a disturbance
occurs during periods of low resource availability, the population-
level consequences are greater and occur faster than if the disturbance
occurs during periods when resource levels are high (Hin et al., 2019).
Further, when resources are not evenly distributed, populations with
cautious strategies and knowledge of resource variation have an
advantage (Pirotta et al., 2020).
Even when modeled alongside several anthropogenic sources of
disturbance (e.g., vessel strike, vessel noise, chemical contaminants,
sonar), several species of marine mammals are most influenced by lack
of prey (Czapanskiy et al., 2021; Murray et al., 2021). Some species
like killer whales are especially sensitive to prey abundance due to
their limited diet (Murray et al., 2021). The short-term energetic cost
of eleven species of cetaceans and mysticetes exposed to mid-frequency
active sonar was influenced more by lost foraging opportunities than
increased locomotor effort during avoidance (Czapanskiy et al., 2021).
Additionally, the model found that mysticetes incurred more energetic
cost than odontocetes, even during mild behavioral responses to sonar.
These results may be useful in the development of future Population
Consequences of Multiple Stressors and PCoD models since they should
seek to qualify cetacean health in a more ecologically relevant manner.
PCoD models have been used to assess the impacts of multiple and
recurring stressors. A marine mammal population that is already subject
to chronic stressors will likely be more vulnerable to acute
disturbances. Models that have looked at populations of cetaceans who
are exposed to multiple stressors over several years have found that
even one major chronic stressor (e.g., epizootic disease, oil spill)
has severe impacts on population size. A layer of one or more stressor
(e.g., seismic surveys) in addition to a chronic stressor (e.g., an oil
spill) can yield devastating impacts on a population. These results may
vary based on species and location, as one population may be more
impacted by chronic shipping noise, while another population may not.
However, just because a population doesn't appear to be impacted by one
chronic stressor (e.g., shipping noise), does not mean they aren't
affected by others (e.g., disease) (Reed et al., 2020). Recurring or
chronic stressors can impact population abundance even when instances
of disturbance are short and have minimal behavioral impact on

[[Page 32197]]

an individual (Farmer et al., 2018a; McHuron et al., 2018b; Pirotta et
al., 2019). Some changes to response variables like pup recruitment
(survival to age one) are not noticeable for several years, as the
impacts on pup survival does not affect the population until those pups
are mature but impacts to young animals will ultimately lead to
population-wide declines. The severity of the repeated disturbance can
also impact a population's long-term reproductive success. Scenarios
with severe repeated disturbance (e.g., 95 percent probability of
exposure, with 95 percent reduction in feeding efficiency) can severely
reduce fecundity and calf survival, while a weaker disturbance (25
percent probability of exposure, with 25 percent reduction in feeding
efficiency) had no population-wide effect on vital rates (Pirotta et
al., 2019).
Farmer et al. (2018a) modeled how an oil spill led to chronic
declines in a sperm whale population over 10 years, and if models
included even one more stressor (i.e., behavioral responses to air
guns), the population declined even further. However, the amount of
additional population decline due to acoustic disturbance depended on
the way the dose-response of the noise levels were modeled. A single
step-function led to higher impacts than a function with multiple steps
and frequency weighting. In addition, the amount of impact from both
disturbances was mediated when the metric in the model that described
animal resilience was changed to increase resilience to disturbance
(e.g., able to make up reserves through increased foraging).
Not all stressors have the same impact for all species and all
locations. Another model analyzed the effect of a number of chronic
disturbances on two bottlenose dolphin populations in Australia over 5
years (Reed et al., 2020). Results indicated that disturbance from
fisheries interactions and shipping noise had little overall impact on
population abundances in either location, even in the most extreme
impact scenarios modeled. At least in this area, other factors (e.g.,
epizootic scenarios) had the largest impact on population size and
fecundity.
Recurring stressors can impact population abundance even when
individual instances of disturbance are short and have minimal
behavioral impact on an individual. A model on California sea lions
introduced a generalized disturbance at different times throughout the
breeding cycle, with their behavior response being an increase in the
duration of a foraging trip by the female (McHuron et al., 2018b). Very
short duration disturbances or responses led to little change,
particularly if the disturbance was a single event, and changes in the
timing of the event in the year had little effect. However, with even
relatively short disturbances or mild responses, when a disturbance was
modeled as recurring there were resulting reductions in population size
and pup recruitment (survival to age one). Often, the effects weren't
noticeable for several years, as the impacts on pup survival did not
affect the population until those pups were mature.

Stranding and Mortality

The definition for a stranding under title IV of the MMPA is an
event in the wild in which (A) a marine mammal is dead and is (i) on a
beach or shore of the United States; or (ii) in waters under the
jurisdiction of the United States (including any navigable waters); or
(B) a marine mammal is alive and is (i) on a beach or shore of the
United States and is unable to return to the water; (ii) on a beach or
shore of the United States and, although able to return to the water,
is in need of apparent medical attention; or (iii) in the waters under
the jurisdiction of the United States (including any navigable waters),
but is unable to return to its natural habitat under its own power or
without assistance (see 16 U.S.C. 1421h(6)). This definition is useful
for considering stranding events even when they occur beyond lands and
waters under the jurisdiction of the United States.
Marine mammal strandings have been linked to a variety of causes,
such as illness from exposure to infectious agents, biotoxins, or
parasites; starvation; unusual oceanographic or weather events; or
anthropogenic causes including fishery interaction, vessel strike,
entrainment, entrapment, sound exposure, or combinations of these
stressors sustained concurrently or in series. Historically, the cause
or causes of most strandings have remained unknown (e.g., Odell et al.,
1980), but the development of trained, professional stranding response
networks and improved analyses have led to a greater understanding of
marine mammal stranding causes (Simeone and Moore 2018).
Numerous studies suggest that the physiology, behavior, habitat,
social relationships, age, or condition of cetaceans may cause them to
strand or might predispose them to strand when exposed to another
phenomenon. These suggestions are consistent with the conclusions of
numerous other studies that have demonstrated that combinations of
dissimilar stressors commonly combine to kill an animal or dramatically
reduce its fitness, even though one exposure without the other does not
produce the same result (Bernaldo de Quiros et al., 2019; Chroussos,
2000; Creel, 2005 Fair and Becker, 2000; Foley et al., 2001; Moberg,
2000; Relyea, 2005a; 2005b, Romero, 2004; Sih et al., 2004).
Historically, stranding reporting and response efforts have been
inconsistent, although significant improvements have occurred over the
last 25 years. Reporting forms for basic (``Level A'') information,
rehabilitation disposition, and human interaction have been
standardized nationally are available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/level-data-collection-marine-mammal-stranding-events. However, data collected
beyond basic information varies by region (and may vary from case to
case) and are not standardized across the United States. Logistical
conditions such as weather, time, location, and decomposition state may
also affect the ability of the stranding network to thoroughly examine
a specimen (Carretta et al., 2023; Moore et al., 2013). While the
investigation of stranded animals provides insight into the types of
threats marine mammal populations face, full investigations are only
possible and conducted on a small fraction of the total number of
strandings that occur, limiting our understanding of the causes of
strandings (Carretta et al., 2016a). Additionally, and due to the
variability in effort and data collected, the ability to interpret
long-term trends in stranded marine mammals is complicated.
In the United States from 2006-2022, there were 27,781 cetacean
strandings and 79,572 pinniped strandings (107,353 total) (P. Onens,
NMFS, pers comm., 2024). Several mass strandings (strandings that
involve two or more individuals of the same species, excluding a single
mother-calf pair) that have occurred over the past two decades have
been associated with anthropogenic activities that introduced sound
into the marine environment such as naval operations and seismic
surveys. An in-depth discussion of strandings can be found in appendix
D of the 2024 HCTT Draft EIS/OEIS and in the Navy's Technical Report on
Marine Mammal Strandings Associated with U.S. Navy Sonar Activities
(U.S. Navy Marine Mammal Program and Space and Naval Warfare Systems
Command Center Pacific, 2017b).
Worldwide, there have been several efforts to identify
relationships between cetacean mass stranding events and

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military active sonar (Cox et al., 2006, Hildebrand, 2004; Taylor et
al., 2004). D'Amico et al. (2009) reviewed beaked whale stranding data
compiled primarily from the published literature, which provides an
incomplete record of stranding events, as many are not written up for
publication, along with unpublished information from some regions of
the world.
Most of the stranding events reviewed by the IWC involved beaked
whales. A mass stranding of goose-beaked whales in the eastern
Mediterranean Sea occurred in 1996 (Frantzis, 1998), and mass stranding
events involving Gervais' beaked whales, Blainville's beaked whales,
and goose-beaked whales occurred off the coast of the Canary Islands in
the late 1980s (Simmonds and Lopez-Jurado, 1991). The stranding events
that occurred in the Canary Islands and Kyparissiakos Gulf in the late
1990s and the Bahamas in 2000 have been the most intensively-studied
mass stranding events and have been associated with naval maneuvers
involving the use of tactical sonar. Other cetacean species with naval
sonar implicated in stranding events include harbor porpoise (Norman et
al., 2004, Wright et al., 2013) and common dolphin (Jepson et al.,
2013).
Strandings Associated With Active Sonar
Over the past 21 years, there have been 5 stranding events
coincident with naval MFAS use in which exposure to sonar is believed
to have been a contributing factor: Greece (1996); the Bahamas (2000);
Madeira (2000); Canary Islands (2002); and Spain (2006) (Cox et al.,
2006; Fernandez, 2006; U.S. Navy Marine Mammal Program and Space and
Naval Warfare Systems Command Center Pacific, 2017). These five mass
strandings have resulted in about 40 known cetacean deaths consisting
mostly of beaked whales and with close linkages to MFAS activity. In
these circumstances, exposure to non-impulsive acoustic energy was
considered a potential indirect cause of death of the marine mammals
(Cox et al., 2006). Only one of these stranding events, the Bahamas
(2000), was associated with exercises conducted by the U.S. Navy.
Additionally, in 2004, during the RIMPAC exercises, between 150 and 200
usually pelagic melon-headed whales occupied the shallow waters of
Hanalei Bay, Kaua[revaps]i, Hawaii for over 28 hours. NMFS determined
that MFAS was a plausible, if not likely, contributing factor in what
may have been a confluence of events that led to the Hanalei Bay
stranding. A number of other stranding events coincident with the
operation of MFAS, including the death of beaked whales or other
species (i.e., minke whales, dwarf sperm whales, pilot whales), have
been reported; however, the majority have not been investigated to the
degree necessary to determine the cause of the stranding. Most
recently, the Independent Scientific Review Panel investigating
potential contributing factors to a 2008 mass stranding of melon-headed
whales in Antsohihy, Madagascar released its final report suggesting
that the stranding was likely initially triggered by an industry
seismic survey (Southall et al., 2013). This report suggests that the
operation of a commercial high-powered 12 kHz multibeam echosounder
during an industry seismic survey was a plausible and likely initial
trigger that caused a large group of melon-headed whales to leave their
typical habitat and then ultimately strand as a result of secondary
factors such as malnourishment and dehydration. The report indicates
that the risk of this particular convergence of factors and ultimate
outcome is likely very low but recommends that the potential be
considered in environmental planning. Because of the association
between tactical MFAS use and a limited number of marine mammal
strandings, the Navy and NMFS have been considering and addressing the
potential for strandings in association with Navy activities for years.
In addition to the proposed mitigation measures intended to more
broadly minimize impacts to marine mammals, the Navy will abide by the
Notification and Reporting Plan, which sets out notification,
reporting, and other requirements when dead, injured, or stranded
marine mammals are detected in certain circumstances.
Greece (1996)--
Twelve goose-beaked whales stranded atypically (in both time and
space) along a 23.7 mi (38.2 km) strand of the Kyparissiakos Gulf coast
on May 12 and 13, 1996 (Frantzis, 1998). From May 11 through May 15,
the North Atlantic Treaty Organization (NATO) research vessel Alliance
was conducting sonar tests with signals of 600 Hz and 3 kHz and source
levels of 228 and 226 dB re 1 [mu]Pa, respectively (D'Amico and
Verboom, 1998; D'Spain et al., 2006). The timing and location of the
testing encompassed the time and location of the strandings (Frantzis,
1998).
Necropsies of eight of the animals were performed but were limited
to basic external examination and sampling of stomach contents, blood,
and skin. No ears or organs were collected, and no histological samples
were preserved. No significant apparent abnormalities or wounds were
found, however examination of photos of the animals, taken soon after
their death, revealed that the eyes of at least four of the individuals
were bleeding (Frantzis, 2004). Stomach contents contained the flesh of
cephalopods, indicating that feeding had recently taken place
(Frantzis, 1998).
All available information regarding the conditions associated with
this stranding event was compiled, and many potential causes were
examined including major pollution events, prominent tectonic activity,
unusual physical or meteorological events, magnetic anomalies,
epizootics, and conventional military activities (International Council
for the Exploration of the Sea, 2005). However, none of these potential
causes coincided in time or space with the mass stranding or could
explain its characteristics (International Council for the Exploration
of the Sea, 2005). The robust condition of the animals, plus the recent
stomach contents, is inconsistent with pathogenic causes. In addition,
environmental causes can be ruled out as there were no unusual
environmental circumstances or events before or during this time period
and within the general proximity (Frantzis, 2004).
Because of the rarity of this mass stranding of goose-beaked whales
in the Kyparissiakos Gulf (first one in historical records), the
probability for the two events (the military exercises and the
strandings) to coincide in time and location, while being independent
of each other, was thought to be extremely low (Frantzis, 1998).
However, because full necropsies had not been conducted, and no
abnormalities were noted, the cause of the strandings could not be
precisely determined (Cox et al., 2006). A Bioacoustics Panel convened
by NATO concluded that the evidence available did not allow them to
accept or reject sonar exposures as a causal agent in these stranding
events. The analysis of this stranding event provided support for, but
no clear evidence for, the cause-and-effect relationship of tactical
sonar training activities and beaked whale strandings (Cox et al.,
2006).
Bahamas (2000)--
NMFS and the Navy prepared a joint report addressing the multi-
species stranding in the Bahamas in 2000, which took place within 24
hours of U.S. Navy ships using MFAS as they passed through the
Northeast and Northwest Providence Channels on March 15-16, 2000. The
ships, which operated both AN/SQS-53C and AN/

[[Page 32199]]

SQS-56 sonar, moved through the channel while emitting pings
approximately every 24 seconds. Of the 17 cetaceans that stranded over
a 36-hour period (goose-beaked whales, Blainville's beaked whales,
minke whales, and a spotted dolphin), 7 animals died on the beach (5
goose-beaked whales, 1 Blainville's beaked whale, and 1 spotted
dolphin), while the other 10 were returned to the water alive (though
their ultimate fate is unknown). As discussed in the Bahamas report
(DOC/DON, 2001), there is no likely association between the minke whale
and spotted dolphin strandings and the operation of MFAS.
Necropsies were performed on five of the stranded beaked whales.
All five necropsied beaked whales were in good body condition, showing
no signs of infection, disease, vessel strike, blunt trauma, or fishery
related injuries, and three still had food remains in their stomachs.
Auditory structural damage was discovered in four of the whales,
specifically bloody effusions or hemorrhaging around the ears.
Bilateral intracochlear and unilateral temporal region subarachnoid
hemorrhage, with blood clots in the lateral ventricles, were found in
two of the whales. Three of the whales had small hemorrhages in their
acoustic fats (located along the jaw and in the melon).
A comprehensive investigation was conducted and all possible causes
of the stranding event were considered, whether they seemed likely at
the outset or not. Based on the way in which the strandings coincided
with ongoing naval activity involving tactical MFAS use, in terms of
both time and geography, the nature of the physiological effects
experienced by the dead animals, and the absence of any other acoustic
sources, the investigation team concluded that MFAS aboard U.S. Navy
ships that were in use during the active sonar exercise in question
were the most plausible source of this acoustic or impulse trauma to
beaked whales. This sound source was active in a complex environment
that included the presence of a surface duct, unusual and steep
bathymetry, a constricted channel with limited egress, intensive use of
multiple, active sonar units over an extended period of time, and the
presence of beaked whales that appear to be sensitive to the
frequencies produced by these active sonars. The investigation team
concluded that the cause of this stranding event was the confluence of
the Navy MFAS and these contributory factors working together and
further recommended that the Navy avoid operating MFAS in situations
where these five factors would be likely to occur. This report does not
conclude that all five of these factors must be present for a stranding
to occur, nor that beaked whales are the only species that could
potentially be affected by the confluence of the other factors. Based
on this, NMFS believes that the operation of MFAS in situations where
surface ducts exist, or in marine environments defined by steep
bathymetry and/or constricted channels may increase the likelihood of
producing a sound field with the potential to cause cetaceans
(especially beaked whales) to strand, and therefore, suggests the need
for increased vigilance while operating MFAS in these areas, especially
when beaked whales (or potentially other deep divers) are likely
present.
Madeira, Portugal (2000)--
From May 10-14, 2000, three goose-beaked whales were found stranded
on two islands in the Madeira Archipelago, Portugal (Cox et al., 2006).
A fourth animal was reported floating in the Madeiran waters by
fisherman but did not come ashore (Ketten, 2005). Joint NATO amphibious
training peacekeeping exercises involving participants from 17
countries and 80 warships, took place in Portugal during May 2-15,
2000.
The bodies of the three stranded whales were examined postmortem
(Ketten, 2005), though only one of the stranded whales was fresh enough
(24 hours after stranding) to be necropsied (Cox et al., 2006). Results
from the necropsy revealed evidence of hemorrhage and congestion in the
right lung and both kidneys (Cox et al., 2006). There was also evidence
of intracochlear and intracranial hemorrhage similar to that which was
observed in the whales that stranded in the Bahamas event (Cox et al.,
2006). There were no signs of blunt trauma, and no major fractures, and
the cranial sinuses and airways were found to be clear with little or
no fluid deposition, which may indicate good preservation of tissues
(Woods Hole Oceanographic Institution, 2005).
Several observations on the Madeira stranded beaked whales, such as
the pattern of injury to the auditory system, are the same as those
observed in the Bahamas strandings. Blood in and around the eyes,
kidney lesions, pleural hemorrhages, and congestion in the lungs are
particularly consistent with the pathologies from the whales stranded
in the Bahamas and are consistent with stress and pressure related
trauma. The similarities in pathology and stranding patterns between
these two events suggest that a similar pressure event may have
precipitated or contributed to the strandings at both sites (Woods Hole
Oceanographic Institution, 2005).
Even though no definitive causal link can be made between the
stranding event and naval exercises, certain conditions may have
existed in the exercise area that, in their aggregate, may have
contributed to the marine mammal strandings (Freitas, 2004): Exercises
were conducted in areas of at least 547 fathoms (1,000 m) depth near a
shoreline where there is a rapid change in bathymetry on the order of
547 to 3,281 fathoms (1,000 to 6,000 m) occurring across a relatively
short horizontal distance (Freitas, 2004); multiple ships were
operating around Madeira, though it is not known if MFAS was used, and
the specifics of the sound sources used are unknown (Cox et al., 2006;
Freitas, 2004); and exercises took place in an area surrounded by
landmasses separated by less than 35 nmi (65 km) and at least 10 nmi
(19 km) in length, or in an embayment. Exercises involving multiple
ships employing MFAS near land may produce sound directed towards a
channel or embayment that may cut off the lines of egress for marine
mammals (Freitas, 2004).
Canary Islands, Spain (2002)--
The southeastern area within the Canary Islands is well known for
aggregations of beaked whales due to its ocean depths of greater than
547 fathoms (1,000 m) within a few hundred meters of the coastline
(Fernandez et al., 2005). On September 24, 2002, 14 beaked whales were
found stranded on Fuerteventura and Lanzarote Islands in the Canary
Islands (International Council for Exploration of the Sea, 2005a).
Seven whales died, while the remaining seven live whales were returned
to deeper waters (Fernandez et al., 2005). Four beaked whales were
found stranded dead over the next three days either on the coast or
floating offshore. These strandings occurred within close proximity of
an international naval exercise that utilized MFAS and involved
numerous surface warships and several submarines. Strandings began
about four hours after the onset of MFAS activity (International
Council for Exploration of the Sea, 2005a; Fernandez et al., 2005).
Eight goose-beaked whales, one Blainville's beaked whale, and one
Gervais' beaked whale were necropsied, six of them within 12 hours of
stranding (Fernandez et al., 2005). No pathogenic bacteria were
isolated from the carcasses (Jepson et al., 2003). The animals
displayed severe vascular congestion and hemorrhage especially around
the

[[Page 32200]]

tissues in the jaw, ears, brain, and kidneys, displaying marked
disseminated microvascular hemorrhages associated with widespread fat
emboli (Jepson et al., 2003; International Council for Exploration of
the Sea, 2005a). Several organs contained intravascular bubbles,
although definitive evidence of gas embolism in vivo is difficult to
determine after death (Jepson et al., 2003). The livers of the
necropsied animals were the most consistently affected organ, which
contained macroscopic gas-filled cavities and had variable degrees of
fibrotic encapsulation. In some animals, cavitary lesions had
extensively replaced the normal tissue (Jepson et al., 2003). Stomachs
contained a large amount of fresh and undigested contents, suggesting a
rapid onset of disease and death (Fernandez et al., 2005). Head and
neck lymph nodes were enlarged and congested, and parasites were found
in the kidneys of all animals (Fernandez et al., 2005).
The association of NATO MFAS use close in space and time to the
beaked whale strandings, and the similarity between this stranding
event and previous beaked whale mass strandings coincident with sonar
use, suggests that a similar scenario and causative mechanism of
stranding may be shared between the events. Beaked whales stranded in
this event demonstrated brain and auditory system injuries,
hemorrhages, and congestion in multiple organs, similar to the
pathological findings of the Bahamas and Madeira stranding events. In
addition, the necropsy results of the Canary Islands stranding event
lead to the hypothesis that the presence of disseminated and widespread
gas bubbles and fat emboli were indicative of nitrogen bubble
formation, similar to what might be expected in decompression sickness
(Jepson et al., 2003; Fern[aacute]ndez et al., 2005).
Hanalei Bay (2004)--
On July 3 and 4, 2004, approximately 150 to 200 melon-headed whales
occupied the shallow waters of Hanalei Bay, Kaua[revaps]i, Hawaii for
over 28 hours. Attendees of a canoe blessing observed the animals
entering Hanalei Bay in a single wave formation at 7 a.m. on July 3,
2004. The animals were observed moving back into the shore from the
mouth of the Bay at 9 a.m. The usually pelagic animals milled in the
shallow bay and were returned to deeper water with human assistance
beginning at 9:30 a.m. on July 4, 2004, and were out of sight by 10:30
a.m.
Only one animal, a calf, was known to have died following this
event. The animal was noted alive and alone in Hanalei Bay on the
afternoon of July 4, 2004, and was found dead in Hanalei Bay the
morning of July 5, 2004. A full necropsy, magnetic resonance imaging,
and computerized tomography examination were performed on the calf to
determine the manner and cause of death. The combination of imaging,
necropsy and histological analyses found no evidence of infectious,
internal traumatic, congenital, or toxic factors. Cause of death could
not be definitively determined, but it is likely that maternal
separation, poor nutritional condition, and dehydration contributed to
the final demise of the animal. Although it is not known when the calf
was separated from its mother, the animals' movement into Hanalei Bay
and subsequent milling and re-grouping may have contributed to the
separation or lack of nursing, especially if the maternal bond was weak
or this was an inexperienced mother with her first calf.
Environmental factors, abiotic and biotic, were analyzed for any
anomalous occurrences that would have contributed to the animals
entering and remaining in Hanalei Bay. The Bay's bathymetry is similar
to many other sites within the Hawaiian Island chain and dissimilar to
sites that have been associated with mass strandings in other parts of
the United States. The weather conditions appeared to be normal for
that time of year with no fronts or other significant features noted.
There was no evidence of unusual distribution, occurrence of predator
or prey species, or unusual harmful algal blooms, although Mobley
(2007) suggested that the full moon cycle that occurred at that time
may have influenced a run of squid into the Bay. Weather patterns and
bathymetry that have been associated with mass strandings elsewhere
were not found to occur in this instance.
The Hanalei Bay event was spatially and temporally correlated with
RIMPAC. Official sonar training and tracking exercises in the PMRF
warning area did not commence until approximately 8 a.m. on July 3 and
were thus ruled out as a possible trigger for the initial movement into
the bay. However, six naval surface vessels transiting to the
operational area on July 2 intermittently transmitted active sonar (for
approximately 9 hours total from 1:15 p.m. to 12:30 a.m.) as they
approached from the south. The potential for these transmissions to
have triggered the whales' movement into Hanalei Bay was investigated.
Analyses with the information available indicated that animals to the
south and east of Kaua[revaps]i could have detected active sonar
transmissions on July 2 and reached Hanalei Bay on or before 7 a.m. on
July 3. However, data limitations regarding the position of the whales
prior to their arrival in Hanalei Bay, the magnitude of sonar exposure,
behavioral responses of melon-headed whales to acoustic stimuli, and
other possible relevant factors preclude a conclusive finding regarding
the role of sonar in triggering this event. Propagation modeling
suggests that transmissions from sonar use during the July 3 exercise
in the PMRF warning area may have been detectable at the mouth of the
Hanalei Bay. If the animals responded negatively to these signals, it
may have contributed to their continued presence in Hanalei Bay. The
U.S. Navy ceased all active sonar transmissions during exercises in
this range on the afternoon of July 3. Subsequent to the cessation of
sonar use, the animals were herded out of Hanalei Bay.
While causation of this stranding event may never be unequivocally
determined, NMFS considers the active sonar transmissions of July 2-3,
2004 a plausible, if not likely, contributing factor in what may have
been a confluence of events. This conclusion is based on the following:
(1) the evidently anomalous nature of the stranding; (2) its close
spatiotemporal correlation with wide-scale, sustained use of sonar
systems previously associated with stranding of deep-diving marine
mammals; (3) the directed movement of two groups of transmitting
vessels toward the southeast and southwest coast of Kaua[revaps]i; (4)
the results of acoustic propagation modeling and an analysis of
possible animal transit times to the bay; and (5) the absence of any
other compelling causative explanation. The initiation and persistence
of this event may have resulted from an interaction of biological and
physical factors. The biological factors may have included the presence
of an apparently uncommon, deep-diving cetacean species (and possibly
an offshore, non-resident group), social interactions among the animals
before or after they entered the Bay, and/or unknown predator or prey
conditions. The physical factors may have included the presence of
nearby deep water, multiple vessels transiting in a directed manner
while transmitting active sonar over a sustained period, the presence
of surface sound ducting conditions, and/or intermittent and random
human interactions while the animals were in Hanalei Bay.
A separate event involving melon-headed whales and rough-toothed
dolphins took place over the same period of time in the Northern
Mariana

[[Page 32201]]

Islands (Jefferson et al., 2006), which is several thousand miles from
Hawaii. Some 500 to 700 melon-headed whales came into Sasanhaya Bay on
July 4, 2004, near the island of Rota and then left of their own accord
after 5.5 hours; no known active sonar transmissions occurred in the
vicinity of that event. The Rota incident led to scientific debate
regarding what, if any, relationship the event had to the simultaneous
events in Hawaii and whether they might be related by some common
factor (e.g., there was a full moon on July 2, 2004, as well as during
other melon-headed whale strandings and nearshore aggregations
(Brownell et al., 2009; Lignon et al., 2007; Mobley, 2007). Brownell et
al. (2009) compared the two incidents, along with one other stranding
incident at Nuka Hiva in French Polynesia and normal resting behaviors
observed at Palmyra Island, in regard to physical features in the
areas, melon-headed whale behavior, and lunar cycles. Brownell et al.,
(2009) concluded that the rapid entry of the whales into Hanalei Bay,
their movement into very shallow water far from the 328-ft (100-m)
contour, their milling behavior (typical pre-stranding behavior), and
their reluctance to leave the bay constituted an unusual event that was
not similar to the events that occurred at Rota, which appear to be
similar to observations of melon-headed whales resting normally at
Palmyra Island. Additionally, there was no correlation between lunar
cycle and the types of behaviors observed in the Brownell et al. (2009)
examples.
Spain (2006)--
The Spanish Cetacean Society reported an atypical mass stranding of
four beaked whales that occurred January 26, 2006, on the southeast
coast of Spain, near Moj[aacute]car (Gulf of Vera) in the Western
Mediterranean Sea. According to the report, two of the whales were
discovered the evening of January 26 and were found to be still alive.
Two other whales were discovered during the day on January 27 but had
already died. The first three animals were located near the town of
Moj[aacute]car and the fourth animal was found dead, a few kilometers
north of the first three animals. From January 25-26, 2006, Standing
NATO Response Force Maritime Group Two (five of seven ships including
one U.S. ship under NATO Operational Control) had conducted active
sonar training against a Spanish submarine within 50 nmi (93 km) of the
stranding site.
Veterinary pathologists necropsied the two male and two female
goose-beaked whales. According to the pathologists, the most likely
primary cause of this type of beaked whale mass stranding event was
anthropogenic acoustic activities, most probably anti-submarine MFAS
used during the military naval exercises. However, no positive acoustic
link was established as a direct cause of the stranding. Even though no
causal link can be made between the stranding event and naval
exercises, certain conditions may have existed in the exercise area
that, in their aggregate, may have contributed to the marine mammal
strandings (Freitas, 2004). Exercises were conducted in areas of at
least 547 fathoms (1,000 m) depth near a shoreline where there is a
rapid change in bathymetry on the order of 547 to 3,281 fathoms (1,000
to 6,000 m) occurring across a relatively short horizontal distance
(Freitas, 2004). Multiple ships (in this instance, five) were operating
MFAS in the same area over extended periods of time (in this case, 20
hours) in close proximity; and exercises took place in an area
surrounded by landmasses, or in an embayment. Exercises involving
multiple ships employing MFAS near land may have produced sound
directed towards a channel or embayment that may have cut off the lines
of egress for the affected marine mammals (Freitas, 2004).
Honaunau Bay (2022)--
On March 25, 2022, a beaked whale (species unknown) stranded in
Honaunau Bay, Hawaii. The animal was observed swimming into shore and
over rocks. Bystanders intervened to turn the animal off of the rocks,
and it swam back out of Honaunau Bay on its own. Locals reported
hearing a siren or alarm type of sound underwater on the same day, and
a Navy vessel was observed from shore on the following day. The Navy
confirmed it used CAS within 27 nmi (50 km) and 48 hours of the time of
stranding, though the stranding has not been definitively linked to the
Navy's CAS use, and there is no evidence to determine whether the
animal had any further short- or long-term effects.
Behaviorally Mediated Responses to MFAS That May Lead to Stranding
Although the confluence of Navy MFAS with the other contributory
factors noted in the 2001 NMFS/Navy joint report was identified as the
cause of the 2000 Bahamas stranding event, the specific mechanisms that
led to that stranding (or the others) are not well understood, and
there is uncertainty regarding the ordering of effects that led to the
stranding. It is unclear whether beaked whales were directly injured by
sound (e.g., acoustically mediated bubble growth, as addressed above)
prior to stranding or whether a behavioral response to sound occurred
that ultimately caused the beaked whales to be injured and strand.
Although causal relationships between beaked whale stranding events
and active sonar remain unknown, several authors have hypothesized that
stranding events involving these species in the Bahamas and Canary
Islands may have been triggered when the whales changed their dive
behavior in a startled response to exposure to active sonar or to
further avoid exposure (Cox et al., 2006; Rommel et al., 2006). These
authors proposed three mechanisms by which the behavioral responses of
beaked whales upon being exposed to active sonar might result in a
stranding event. These include the following: gas bubble formation
caused by excessively fast surfacing; remaining at the surface too long
when tissues are supersaturated with nitrogen; or diving prematurely
when extended time at the surface is necessary to eliminate excess
nitrogen. More specifically, beaked whales that occur in deep waters
that are in close proximity to shallow waters (for example, the
``canyon areas'' that are cited in the Bahamas stranding event; see
D'Spain and D'Amico, 2006), may respond to active sonar by swimming
into shallow waters to avoid further exposures and strand if they were
not able to swim back to deeper waters. Second, beaked whales exposed
to active sonar might alter their dive behavior. Changes in their dive
behavior might cause them to remain at the surface or at depth for
extended periods of time which could lead to hypoxia directly by
increasing their oxygen demands or indirectly by increasing their
energy expenditures (to remain at depth) and increase their oxygen
demands as a result. If beaked whales are at depth when they detect a
ping from an active sonar transmission and change their dive profile,
this could lead to the formation of significant gas bubbles, which
could damage multiple organs or interfere with normal physiological
function (Cox et al., 2006; Rommel et al., 2006; Zimmer and Tyack,
2007). Baird et al. (2006) found that slow ascent rates from deep dives
and long periods of time spent within 164 ft (50 m) of the surface were
typical for both goose-beaked and Blainville's beaked whales, the two
species involved in mass strandings related to naval sonar. These two
behavioral mechanisms may be necessary to purge excessive dissolved
nitrogen concentrated in their tissues during

[[Page 32202]]

their frequent long dives (Baird et al., 2005). Baird et al. (2005)
further suggests that abnormally rapid ascents or premature dives in
response to high-intensity sonar could indirectly result in physical
harm to the beaked whales, through the mechanisms described above (gas
bubble formation or non-elimination of excess nitrogen). In a review of
the previously published data on the potential impacts of sonar on
beaked whales, Bernaldo de Quir[oacute]s et al. (2019) suggested that
the effect of MFAS on beaked whales varies among individuals or
populations, and that predisposing conditions such as previous exposure
to sonar and individual health risk factors may contribute to
individual outcomes (e.g., decompression sickness).
Because many species of marine mammals make repetitive and
prolonged dives to great depths, it has long been assumed that marine
mammals have evolved physiological mechanisms to protect against the
effects of rapid and repeated decompressions. Although several
investigators have identified physiological adaptations that may
protect marine mammals against nitrogen gas supersaturation (i.e.,
alveolar collapse and elective circulation; Kooyman et al., 1972;
Ridgway and Howard, 1979), Ridgway and Howard (1979) reported that
bottlenose dolphins that were trained to dive repeatedly had muscle
tissues that were substantially supersaturated with nitrogen gas.
Houser et al. (2001b) used these data to model the accumulation of
nitrogen gas within the muscle tissue of other marine mammal species
and concluded that cetaceans that dive deep and have slow ascent or
descent speeds would have tissues that are more supersaturated with
nitrogen gas than other marine mammals. Based on these data, Cox et al.
(2006) hypothesized that a critical dive sequence might make beaked
whales more prone to stranding in response to acoustic exposures. The
sequence began with (1) very deep (to depths as deep as 1.2 mi (2 km))
and long (as long as 90 minutes) foraging dives; (2) relatively slow,
controlled ascents; and (3) a series of ``bounce'' dives between 328
and 1,312 ft (100 and 400 m) in depth (see Zimmer and Tyack, 2007).
They concluded that acoustic exposures that disrupted any part of this
dive sequence (for example, causing beaked whales to spend more time at
surface without the bounce dives that are necessary to recover from the
deep dive) could produce excessive levels of nitrogen supersaturation
in their tissues, leading to gas bubble and emboli formation that
produces pathologies similar to decompression sickness.
Zimmer and Tyack (2007) modeled nitrogen tension and bubble growth
in several tissue compartments for several hypothetical dive profiles
and concluded that repetitive shallow dives (defined as a dive where
depth does not exceed the depth of alveolar collapse, approximately 236
ft (72 m) for goose-beaked whale), perhaps as a consequence of an
extended avoidance response to sonar sound, could pose a risk for
decompression sickness and that this risk should increase with the
duration of the response. Their models also suggested that
unrealistically rapid rates of ascent from normal dive behaviors are
unlikely to result in supersaturation to the extent that bubble
formation would be expected. Tyack et al. (2006) suggested that emboli
observed in animals exposed to mid-frequency range sonar (Jepson et
al., 2003; Fernandez et al., 2005) could stem from a behavioral
response that involves repeated dives shallower than the depth of lung
collapse. Given that nitrogen gas accumulation is a passive process
(i.e., nitrogen is metabolically inert), a bottlenose dolphin was
trained to repetitively dive a profile predicted to elevate nitrogen
saturation to the point that nitrogen bubble formation was predicted to
occur. However, inspection of the vascular system of the dolphin via
ultrasound did not demonstrate the formation of asymptomatic nitrogen
gas bubbles (Houser et al., 2010). Baird et al. (2008), in a beaked
whale tagging study off Hawaii, showed that deep dives are equally
common during day or night, but ``bounce dives'' are typically a
daytime behavior, possibly associated with visual predator avoidance.
This may indicate that ``bounce dives'' are associated with something
other than behavioral regulation of dissolved nitrogen levels, which
would be necessary day and night.
Additional predictive modeling conducted to date has been performed
with many unknowns about the respiratory physiology of deep-diving
breath-hold animals. For example, Denk et al. (2020) found intra-
species differences in the compliance of tracheobronchial structures of
post-mortem cetaceans and pinnipeds under diving hydrostatic pressures,
which would affect depth of alveolar collapse. Although, as
hypothesized by Garcia Parraga et al. (2018) and reviewed in Fahlman et
al., (2021), mechanisms may exist that allow marine mammals to create a
pulmonary shunt without the need for hydrostatic pressure-induced lung
collapse (i.e., by varying perfusion to the lung independent of lung
collapse and degree of ventilation). If such a mechanism exists, then
assumptions in prior gas models require reconsideration, the degree of
nitrogen gas accumulation associated with dive profiles needs to be re-
evaluated, and behavioral responses potentially leading to a
destabilization of the relationship between pulmonary ventilation and
perfusion should be considered. Costidis and Rommel (2016) suggested
that gas exchange may continue to occur across the tissues of air-
filled sinuses in deep diving odontocetes below the depth of lung
collapse if hydrostatic pressures are high enough to drive gas exchange
across into non-capillary veins.
If marine mammals respond to an Action Proponent vessel that is
transmitting active sonar in the same way that they might respond to a
predator, their probability of flight responses could increase when
they perceive that Action Proponent vessels are approaching them
directly, because a direct approach may convey detection and intent to
capture (Burger and Gochfeld, 1981, 1990; Cooper, 1997; Cooper, 1998).
The probability of flight responses could also increase as received
levels of active sonar increase (and the ship is, therefore, closer)
and as ship speeds increase (that is, as approach speeds increase). For
example, the probability of flight responses in ringed seals (Born et
al., 1999), Pacific brant (Branta bernicla nigricans) and Canada geese
(B. canadensis) increased as a helicopter or fixed-wing aircraft
approached groups of these animals more directly (Ward et al., 1999).
Bald eagles (Haliaeetus leucocephalus) perched on trees alongside a
river were also more likely to flee from a paddle raft when their
perches were closer to the river or were closer to the ground (Steidl
and Anthony, 1996).
Despite the many theories involving bubble formation (both as a
direct cause of injury (see Non-Auditory Injury section) and an
indirect cause of stranding), Southall et al. (2007) summarizes that
there is either scientific disagreement or a lack of information
regarding each of the following important points: (1) received
acoustical exposure conditions for animals involved in stranding
events; (2) pathological interpretation of observed lesions in stranded
marine mammals; (3) acoustic exposure conditions required to induce
such physical trauma directly; (4) whether noise exposure may cause
behavioral responses (e.g., atypical diving behavior) that secondarily
cause bubble formation and tissue damage; and (5) the extent the post
mortem artifacts introduced by

[[Page 32203]]

decomposition before sampling, handling, freezing, or necropsy
procedures affect interpretation of observed lesions.
Strandings Associated With Explosive Use
Silver Strand (2011)--
During a Navy training event on March 4, 2011, at the Silver Strand
Training Complex in San Diego, California, three or possibly four
dolphins were killed in an explosion. During an underwater detonation
training event, a pod of 100 to 150 long-beaked common dolphins were
observed moving towards the 700-yard (yd) (640.1-m) exclusion zone
around the explosive charge, monitored by personnel in a safety boat
and participants in a dive boat. Approximately 5 minutes remained on a
time-delay fuse connected to a single 8.76 lb (3.97 kg) explosive
charge (C-4 and detonation cord). Although the dive boat was placed
between the pod and the explosive in an effort to guide the dolphins
away from the area, that effort was unsuccessful and three long-beaked
common dolphins near the explosion died. The Navy recovered those
animals and transferred them to the local stranding network for
necropsy. In addition to the three dolphins found dead on March 4, the
remains of a fourth dolphin were discovered on March 7, 2011, near
Oceanside, California (3 days later and approximately 42 mi (68 km)
north of the detonation), which might also have been related to this
event. Upon necropsy, all four animals were found to have sustained
typical mammalian primary blast injuries (Danil and St. Leger, 2011).
Association of the fourth stranding with the training event is
uncertain because dolphins strand on a regular basis in the San Diego
area. Details such as the dolphins' depth and distance from the
explosive at the time of the detonation could not be estimated from the
250 yd (228.6 m) standoff point of the observers in the dive boat or
the safety boat.
These dolphin mortalities are the only known occurrence of a Navy
training or testing event involving impulsive energy (underwater
detonation) that caused mortality or injury to a marine mammal. Despite
this being a rare occurrence, the Navy reviewed training requirements,
safety procedures, and possible mitigation measures and implemented
changes to reduce the potential for this to occur in the future.
Discussions of procedures associated with underwater explosives
training and other training events are presented in the Proposed
Mitigation Measures section.
Kyle of Durness, Scotland (2011)--
On July 22, 2011, a mass stranding event involving long-finned
pilot whales occurred at Kyle of Durness, Scotland. An investigation by
Brownlow et al. (2015) considered unexploded ordnance detonation
activities at a Ministry of Defense bombing range, conducted by the
Royal Navy prior to and during the strandings, as a plausible
contributing factor in the mass stranding event. While Brownlow et al.
(2015) concluded that the serial detonations of underwater ordnance
were an influential factor in the mass stranding event (along with the
presence of a potentially compromised animal and navigational error in
a topographically complex region), they also suggest that mitigation
measures--which included observations from a zodiac only and by
personnel not experienced in marine mammal observation, among other
deficiencies--were likely insufficient to assess if cetaceans were in
the vicinity of the detonations. The authors also cite information from
the Ministry of Defense indicating ``an extraordinarily high level of
activity'' (i.e., frequency and intensity of underwater explosions) on
the range in the days leading up to the stranding.
Strandings on the Hawaii and California Coasts
Stranded marine mammals are reported along the Hawaii and
California coasts each year. Marine mammals strand due to natural or
anthropogenic causes, and the majority of reported type of occurrences
in marine mammal strandings in this region include fishery
interactions, illness, predation, and vessel strikes (Carretta et al.,
2024).

Potential Effects of Vessel Strike

Vessel strikes of marine mammals can result in death or serious
injury of the animal. Wounds resulting from vessel strike may include
massive trauma, hemorrhaging, broken bones, or propeller lacerations
(Knowlton and Kraus, 2001). An animal at the surface could be struck
directly by a vessel, a surfacing animal could hit the bottom of a
vessel, or an animal just below the surface could be cut by a vessel's
propeller. Superficial strikes may not kill or result in the death of
the animal. Lethal interactions are typically associated with large
whales, which are occasionally found draped across the bulbous bow of
large commercial ships upon arrival in port. Although smaller cetaceans
are more maneuverable in relation to large vessels than are large
whales, they may also be susceptible to strike. The severity of
injuries typically depends on the size and speed of the vessel
(Knowlton and Kraus, 2001; Laist et al., 2001; Vanderlaan and Taggart,
2007; Conn and Silber, 2013). Impact forces increase with speed, as
does the probability of a strike at a given distance (Silber et al.,
2010; Gende et al., 2011).
The most vulnerable marine mammals are those that spend extended
periods of time at the surface in order to restore oxygen levels within
their tissues after deep dives (e.g., the sperm whale; Jaquet and
Whitehead, 1996; Watkins et al., 1999). In addition, some baleen whales
seem generally unresponsive to vessel sound, making them more
susceptible to vessel strikes (Nowacek et al., 2004). These species are
primarily large, slow moving whales. Marine mammal responses to vessels
may include avoidance and changes in dive pattern (NRC, 2003).
Wounds resulting from vessel strike may include massive trauma,
hemorrhaging, broken bones, or propeller lacerations (Knowlton and
Kraus, 2001). An animal at the surface could be struck directly by a
vessel, a surfacing animal could hit the bottom of a vessel, or an
animal just below the surface could be cut by a vessel's propeller.
Impact forces increase with speed as does the probability of a strike
at a given distance (Silber et al., 2010; Gende et al., 2011). An
examination of all known vessel strikes from all shipping sources
(civilian and military) indicates vessel speed is a principal factor in
whether a vessel strike results in death or serious injury (Knowlton
and Kraus, 2001; Laist et al., 2001; Jensen and Silber, 2003; Pace and
Silber, 2005; Vanderlaan and Taggart, 2007). In assessing records in
which vessel speed was known, Laist et al. (2001) found a direct
relationship between the occurrence of a whale strike and the speed of
the vessel involved in the collision. The authors concluded that most
deaths occurred when a vessel was traveling in excess of 13 kn (24 km/
hr).
Jensen and Silber (2003) detailed 292 records of known or probable
vessel strikes of all large whale species from 1975 to 2002. Of these,
vessel speed at the time of collision was reported for 58 cases. Of
these 58 cases, 39 (or 67 percent) resulted in serious injury or death
(19 of those resulted in serious injury as determined by blood in the
water, propeller gashes, or severed tailstock, and fractured skull,
jaw, vertebrae, hemorrhaging, massive bruising or other injuries noted
during necropsy, and 20 resulted in death).

[[Page 32204]]

Operating speeds of vessels that struck various species of large whales
ranged from 2 to 51 kn (3.7 to 94.5 km/hr). The majority (79 percent)
of these strikes occurred at speeds of 13 kn (24 km/hr) or greater. The
average speed that resulted in serious injury or death was 18.6 kn
(34.4 km/hr). Pace and Silber (2005) found that the probability of
death or serious injury increased rapidly with increasing vessel speed.
Specifically, the predicted probability of serious injury or death
increased from 45 to 75 percent as vessel speed increased from 10 to 14
kn (18.5 to 25.9 km/hr) and exceeded 90 percent at 17 kn (31.5 km/hr).
Higher speeds during strikes result in greater force of impact and also
appear to increase the chance of severe injuries or death. While
modeling studies have suggested that hydrodynamic forces pulling whales
toward the vessel hull increase with increasing speed (Clyne, 1999;
Knowlton et al., 1995), this is inconsistent with Silber et al. (2010),
which demonstrated that there is no such relationship (i.e.,
hydrodynamic forces are independent of speed).
In a separate study, Vanderlaan and Taggart (2007) analyzed the
probability of lethal mortality of large whales at a given speed,
showing that the greatest rate of change in the probability of a lethal
injury to a large whale as a function of vessel speed occurs between
8.6 and 15 kn (15.9 and 27.8 km/hr). The chances of a lethal injury
decline from approximately 80 percent at 15 kn to approximately 20
percent at 8.6 kn (15.9 km/hr). At speeds below 11.8 kn (21.9 km/hr),
the chances of lethal injury drop below 50 percent, while the
probability asymptotically increases toward 100 percent above 15 kn
(27.8 km/hr). Garrison et al. (2025) reviewed and updated available
data on whale-vessel interactions in U.S. waters to determine the
effects of vessel speed and size on lethality of strikes of large
whales and found vessel size class had a significant effect on the
probability of lethality. Decreasing vessel speeds reduced the
likelihood of a lethal outcome for all vessel size classes modeled,
with the strongest effect for vessels less than 354 ft (108 m) long.
Notably, the probability that a strike by a very large (i.e., in
length) vessel will be lethal exceeded 0.80 at all speeds greater than
5 kn (9.26 km/hr) (Garrison et al., 2025).
The Jensen and Silber (2003) report notes that the database
represents a minimum number of strikes, because the vast majority
probably goes undetected or unreported. In contrast, Action Proponent
vessels are likely to detect any strike that does occur because of the
required personnel training and Lookouts (as described in the Proposed
Mitigation Measures section), and they are required to report all
vessel strikes involving marine mammals.
In the HCTT Study Area, commercial traffic is heaviest in the
nearshore waters, near major ports and in the shipping lanes along the
California coast and in Hawaii (specifically Honolulu), including a
lane of high intensity farther off the California coast running
northwest-southeast, which is a great circle route between the Panama
Canal and Asia. Military vessel traffic is primarily concentrated in
the waters off San Diego, CA, and the coasts of the Hawaiian islands,
particularly south of O[revaps]ahu and east of Hawaii Island (Navy
2025, unpublished data).
In the SOCAL portion of the Study Area, the U.S. Navy has struck a
total of 19 marine mammals in the 32-year period from 1993 through
2025, an average of just under one per year. The species struck include
gray whale, humpback whale, blue whale, and either fin or sei whale,
though for some strikes, the species could not be determined.
In the HRC portion of the Study Area, the Navy struck a total of
five marine mammals in the 22-year period from 1993 through 2025, an
average of zero to one strikes per year. The Coast Guard has had one
known marine mammal strike in Hawaii, a humpback whale in 2020. Of the
five Navy vessel strikes over the 22-year period in the HRC, all were
reported as injuries. The vessel struck species include: one humpback
whale in 1998, one unknown species and one humpback whale in 2003, one
sperm whale in 2007, and an unknown species in 2008. No more than two
whales were struck by Navy vessels in any given year in the HRC portion
of the HSTT within the last 32 years.
Between 2007 and 2009, the Navy developed and distributed
additional training, mitigation, and reporting tools to Navy operators
to improve marine mammal protection and to ensure compliance with
permit requirements. In 2009, the Navy implemented Marine Species
Awareness Training designed to improve effectiveness of visual
observation for marine mammals and other marine resources. In
subsequent years, the Navy issued refined policy guidance on vessel
strikes in order to collect the most accurate and detailed data
possible in response to a possible incident (also see the Notification
and Reporting Plan for this proposed rule). For over a decade, the Navy
has implemented the Protective Measures Assessment Protocol software
tool, which provides operators with notification of the required
mitigation and a visual display of the planned training or testing
activity location overlaid with relevant environmental data.

Marine Mammal Habitat

The proposed training and testing activities could potentially
affect marine mammal habitat through the introduction of impacts to the
prey species of marine mammals, acoustic habitat (sound in the water
column), water quality, and biologically important habitat for marine
mammals. Each of these potential effects was considered in the 2024
HCTT Draft EIS/OEIS and was determined not to have adverse effects on
marine mammal habitat. Based on the information below and the
supporting information included in the 2024 HCTT Draft EIS/OEIS, NMFS
has determined that the proposed training and testing activities would
not have adverse or long-term impacts on marine mammal habitat.
Effects to Prey
Sound may affect marine mammals through impacts on the abundance,
behavior, or distribution of prey species (e.g., crustaceans,
cephalopods, fish, zooplankton). Marine mammal prey varies by species,
season, and location and, for some species, is not well-documented.
Here, we describe studies regarding the effects of noise on known
marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
The most likely effects on fishes exposed to loud, intermittent, low-
frequency sounds are behavioral responses (i.e., flight or avoidance).
Short duration, sharp sounds (such as pile driving or air guns) can
cause overt or subtle changes in fish behavior and local distribution.
The response of fish to acoustic sources depends on the physiological
state of the fish, past exposures, motivation (e.g., feeding, spawning,
migration), and other environmental factors. Key impacts to fishes may
include behavioral responses, hearing damage, barotrauma (i.e.,
pressure-related injuries), and mortality. While it is clear that the
behavioral responses of individual prey, such as displacement or other
changes in distribution, can have direct impacts on the foraging
success of marine mammals, the effects on marine mammals of individual
prey that experience hearing damage, barotrauma, or mortality is less
clear,

[[Page 32205]]

though obviously population scale impacts that meaningfully reduce the
amount of prey available could have more serious impacts.
Fishes, like other vertebrates, have a variety of different sensory
systems to glean information from ocean around them (Astrup and Mohl,
1993; Astrup, 1999; Braun and Grande, 2008; Carroll et al., 2017;
Hawkins and Johnstone, 1978; Ladich and Popper, 2004; Ladich and
Schulz-Mirbach, 2016; Mann, 2016; Nedwell et al., 2004; Popper et al.,
2003; Popper et al., 2005). Depending on their hearing anatomy and
peripheral sensory structures, which vary among species, fishes hear
sounds using pressure and particle motion sensitivity capabilities and
detect the motion of surrounding water (Fay et al., 2008), while
terrestrial vertebrates generally only detect pressure. Most marine
fishes primarily detect particle motion using the inner ear and lateral
line system, while some fishes possess additional morphological
adaptations or specializations that can enhance their sensitivity to
sound pressure, such as a gas-filled swim bladder (Braun and Grande,
2008; Popper and Fay, 2011).
Hearing capabilities vary considerably between different fish
species with data only available for just over 100 species out of the
34,000 marine and freshwater fish species (Eschmeyer and Fong, 2016).
In order to better understand acoustic impacts on fishes, fish hearing
groups are defined by species that possess a similar continuum of
anatomical features which result in varying degrees of hearing
sensitivity (Popper and Hastings, 2009a). There are four hearing groups
defined for all fish species (modified from Popper et al., 2014) within
this analysis and they include: fishes without a swim bladder (e.g.,
flatfish, sharks, rays, etc.); fishes with a swim bladder not involved
in hearing (e.g., salmon, cod, pollock, etc.); fishes with a swim
bladder involved in hearing (e.g., sardines, anchovy, herring, etc.);
and fishes with a swim bladder involved in hearing and high-frequency
hearing (e.g., shad and menhaden). Most marine mammal fish prey species
would not be likely to perceive or hear mid- or high-frequency sonars.
While hearing studies have not been done on sardines and northern
anchovies, it would not be unexpected for them to possess hearing
similarities to Pacific herring (up to 2-5 kHz) (Mann et al., 2005).
Currently, less data are available to estimate the range of best
sensitivity for fishes without a swim bladder.
In terms of physiology, multiple scientific studies have documented
a lack of mortality or physiological effects to fish from exposure to
low- and mid-frequency sonar and other sounds (Cox et al., 2018;
Halvorsen et al., 2012; J[oslash]rgensen et al., 2005; Kane et al.,
2010; Kvadsheim and Sevaldsen, 2005; Popper et al., 2007; Popper et
al., 2016; Watwood et al., 2016). Techer et al. (2017) exposed carp in
floating cages for up to 30 days to low-power 23 and 46 kHz sources
without any significant physiological response. Other studies have
documented either a lack of TTS in species whose hearing range cannot
perceive military sonar, or for those species that could perceive
sonar-like signals, any TTS experienced would be recoverable (Halvorsen
et al., 2012; Ladich and Fay, 2013; Popper and Hastings, 2009a, 2009b;
Popper et al., 2014; Smith, 2016). Only fishes that have
specializations that enable them to hear sounds above about 2,500 Hz
(2.5 kHz) such as herring (Halvorsen et al., 2012; Mann et al., 2005;
Mann, 2016; Popper et al., 2014) would have the potential to receive
TTS or exhibit behavioral responses from exposure to mid-frequency
sonar. In addition, any sonar induced TTS to fish whose hearing range
could perceive sonar would only occur in the narrow spectrum of the
source (e.g., 3.5 kHz) compared to the fish's total hearing range
(e.g., 0.01 kHz to 5 kHz). Overall, military sonar sources are much
narrower in terms of source frequency compared to a given fish species
full hearing range (Halvorsen et al., 2012; J[oslash]rgensen et al.,
2005; Juanes et al., 2017; Kane et al., 2010; Kvadsheim and Sevaldsen,
2005; Popper et al., 2007; Popper and Hawkins, 2016; Watwood et al.,
2016).
In terms of behavioral responses, Juanes et al. (2017) discuss the
potential for negative impacts from anthropogenic soundscapes on fish,
but the author's focus was on broader based sounds such as ship and
boat noise sources. Watwood et al. (2016) also documented no behavioral
responses by reef fish after exposure to MFAS. Doksaeter et al. (2009;
2012) reported no behavioral responses to mid-frequency naval sonar by
Atlantic herring; specifically, no escape responses (vertically or
horizontally) were observed in free swimming herring exposed to mid-
frequency sonar transmissions. Based on these results (Doksaeter et
al., 2009; Doksaeter et al., 2012; Sivle et al., 2012), Sivle et al.
(2015) created a model in order to report on the possible population-
level effects on Atlantic herring from active naval sonar. The authors
concluded that the use of naval sonar poses little risk to populations
of herring regardless of season, even when the herring populations are
aggregated and directly exposed to sonar. Finally, Bruintjes et al.
(2016) commented that fish exposed to any short-term noise within their
hearing range might initially startle, but would quickly return to
normal behavior.
Occasional behavioral responses to intermittent explosions and
impulsive sound sources are unlikely to cause long-term consequences
for individual fish or populations. Fish that experience hearing loss
as a result of exposure to explosions and impulsive sound sources may
have a reduced ability to detect relevant sounds such as predators,
prey, or social vocalizations. However, PTS has not been known to occur
in fishes and any hearing loss in fish may be as temporary as the
timeframe required to repair or replace the sensory cells that were
damaged or destroyed (Popper et al., 2005; Popper et al., 2014; Smith
et al., 2006). It is not known if damage to auditory nerve fibers could
occur, and if so, whether fibers would recover during this process.
It is also possible for fish to be injured or killed by an
explosion in the immediate vicinity of the surface from dropped or
fired ordnance, or near the bottom from shallow water bottom-placed
underwater mine warfare detonations. Physical effects from pressure
waves generated by underwater sounds (e.g., underwater explosions)
could potentially affect fish within proximity of training or testing
activities. SPLs of sufficient strength have been known to cause injury
to fish and fish mortality (summarized in Popper et al., 2014). The
shock wave from an underwater explosion is lethal to fish at close
range, causing massive organ and tissue damage and internal bleeding
(Keevin and Hempen, 1997). At greater distance from the detonation
point, the extent of mortality or injury depends on a number of factors
including fish size, body shape, orientation, and species (Keevin and
Hempen, 1997; Wright, 1982). At the same distance from the source,
larger fish are generally less susceptible to death or injury,
elongated forms that are round in cross-section are less at risk than
deep-bodied forms, and fish oriented sideways to the blast suffer the
greatest impact (Edds-Walton and Finneran, 2006; O'Keeffe, 1984;
O'Keeffe and Young, 1984; Wiley et al., 1981; Yelverton et al., 1975).
Species with gas-filled organs are more susceptible to injury and
mortality than those without them (Gaspin, 1975; Gaspin et al., 1976;
Goertner et al., 1994). Barotrauma injuries have been documented during
controlled exposure to impact pile driving (an impulsive noise source,
as are explosives and air

[[Page 32206]]

guns) (Halvorsen et al., 2012b; Casper et al., 2013).
Fish not killed or driven from a location by an explosion might
change their behavior, feeding pattern, or distribution. Changes in
behavior of fish have been observed as a result of sound produced by
explosives, with effect intensified in areas of hard substrate (Wright,
1982). However, Navy explosive use avoids hard substrate to the best
extent practical during underwater detonations, or deep-water surface
detonations. Stunning from pressure waves could also temporarily
immobilize fish, making them more susceptible to predation. The
abundances of various fish (and invertebrates) near the detonation
point for explosives could be altered for a few hours before animals
from surrounding areas repopulate the area. However, these populations
would likely be replenished as waters near the detonation point are
mixed with adjacent waters. Repeated exposure of individual fish to
sounds from underwater explosions is not likely and exposures are
expected to be short-term and localized. Long-term consequences for
fish populations would not be expected. Several studies have
demonstrated that air gun sounds might affect the distribution and
behavior of some fishes, potentially impacting foraging opportunities
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012;
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999;
Paxton et al., 2017).
For fishes exposed to military sonar, there would be limited sonar
use spread out in time and space across large offshore areas such that
only small areas are actually ensonified (tens of miles) compared to
the total life history distribution of fish prey species. There would
be no probability for mortality or physical injury from sonar, and for
most species, no or little potential for hearing or behavioral effects,
except to a few select fishes with hearing specializations (e.g.,
herring) that could perceive mid-frequency sonar. Training and testing
exercises involving explosions are dispersed in space and time;
therefore, repeated exposure of individual fishes is unlikely.
Mortality and injury effects to fishes from explosives would be
localized around the area of a given in-water explosion, but only if
individual fish and the explosive (and immediate pressure field) were
co-located at the same time. Fishes deeper in the water column or on
the bottom would not be affected by water surface explosions. Repeated
exposure of individual fish to sound and energy from underwater
explosions is not likely given fish movement patterns, especially
schooling prey species. Most acoustic effects, if any, are expected to
be short-term and localized. Long-term consequences for fish
populations, including key prey species within the HCTT Study Area,
would not be expected.
Vessels and in-water devices do not normally collide with adult
fish, particularly those that are common marine mammal prey, most of
which can detect and avoid them. Exposure of fishes to vessel strike
stressors is limited to those fish groups that are large, slow-moving,
and may occur near the surface, such as ocean sunfish, whale sharks,
basking sharks, and manta rays. These species are distributed widely in
offshore portions of the HCTT Study Area. Any isolated cases of a
military vessel striking an individual could injure that individual,
impacting the fitness of an individual fish. Vessel strikes would not
pose a risk to most of the other marine fish groups, because many fish
can detect and avoid vessel movements, making strikes rare and allowing
the fish to return to their normal behavior after the ship or device
passes. As a vessel approaches a fish, they could have a detectable
behavioral or physiological response (e.g., swimming away and increased
heart rate) as the passing vessel displaces them. However, such
responses are not expected to have lasting effects on the survival,
growth, recruitment, or reproduction of these marine fish groups at the
population level and therefore would not have an impact on marine
mammal species as prey items.
In addition to fish, prey sources such as marine invertebrates
could potentially be impacted by sound stressors as a result of the
proposed activities. However, most marine invertebrates' ability to
sense sounds is very limited. In most cases, marine invertebrates would
not respond to impulsive and non-impulsive sounds, although they may
detect and briefly respond to nearby low-frequency sounds. These short-
term responses would likely be inconsequential to invertebrate
populations.
Invertebrates appear to be able to detect sounds (Pumphrey, 1950;
Frings and Frings, 1967) and are most sensitive to low-frequency sounds
(Packard et al., 1990; Budelmann and Williamson, 1994; Lovell et al.,
2005; Mooney et al., 2010). Data on response of invertebrates such as
squid, another marine mammal prey species, to anthropogenic sound is
more limited (de Soto, 2016; Sole et al., 2017). Data suggest that
cephalopods are capable of sensing the particle motion of sounds and
detect low frequencies up to 1-1.5 kHz, depending on the species, and
so are likely to detect air gun noise (Kaifu et al., 2008; Hu et al.,
2009; Mooney et al., 2010; Samson et al., 2014). Sole et al. (2017)
reported physiological injuries to cuttlefish in cages placed at-sea
when exposed during a controlled exposure experiment to low-frequency
sources (315 Hz, 139 to 142 dB re: 1 [mu]Pa\2\ and 400 Hz, 139 to 141
dB re: 1 [mu]Pa\2\). Fewtrell and McCauley (2012) reported squids
maintained in cages displayed startle responses and behavioral changes
when exposed to seismic air gun sonar (136-162 re: 1
[mu]Pa\2\[middot]s). However, the sources Sole et al. (2017) and
Fewtrell and McCauley (2012) used are not similar and were much lower
than typical Navy sources within the HCTT Study Area. Nor do the
studies address the issue of individual displacement outside of a zone
of impact when exposed to sound. Jones et al. (2020) found that when
squid (Doryteuthis (Amerigo) pealeii) were exposed to impulse pile
driving noise, body pattern changes, inking, jetting, and startle
responses were observed and nearly all squid exhibited at least one
response. However, these responses occurred primarily during the first
eight impulses and diminished quickly, indicating potential rapid,
short-term habituation.
Cephalopods have a specialized sensory organ inside the head called
a statocyst that may help an animal determine its position in space
(orientation) and maintain balance (Budelmann, 1992). Packard et al.
(1990) showed that cephalopods were sensitive to particle motion, not
sound pressure, and Mooney et al. (2010) demonstrated that squid
statocysts act as an accelerometer through which particle motion of the
sound field can be detected. Auditory injuries (lesions occurring on
the statocyst sensory hair cells) have been reported upon controlled
exposure to low-frequency sounds, suggesting that cephalopods are
particularly sensitive to low-frequency sound (Andre et al., 2011; Sole
et al., 2013). Behavioral responses, such as inking and jetting, have
also been reported upon exposure to low-frequency sound (McCauley et
al., 2000b; Samson et al., 2014). Squids, like most fish species, are
likely more sensitive to low frequency sounds, and may not perceive
mid- and high-frequency sonars such as Navy sonars. Cumulatively for
squid as a prey species, individual and population impacts from
exposure to Navy sonar and explosives, like fish, are not likely to be
significant, and explosive impacts would be short-term and localized.

[[Page 32207]]

Explosions and pile driving would likely kill or injure nearby
marine invertebrates. Vessels also have the potential to impact marine
invertebrates by disturbing the water column or sediments, or directly
striking organisms (Bishop, 2008). The propeller wash (water displaced
by propellers used for propulsion) from vessel movement and water
displaced from vessel hulls can potentially disturb marine
invertebrates in the water column and is a likely cause of zooplankton
mortality (Bickel et al., 2011). The localized and short-term exposure
to explosions or vessels could displace, injure, or kill zooplankton,
invertebrate eggs or larvae, and macro-invertebrates. However,
mortality or long-term consequences for a few animals is unlikely to
have measurable effects on overall populations. Long-term consequences
to marine invertebrate populations would not be expected as a result of
exposure to sounds of vessels in the HCTT Study Area.
Impacts to benthic communities from impulsive sound generated by
active acoustic sound sources are not well documented. (e.g.,
Andriguetto-Filho et al., 2005; Payne et al., 2007; 2008; Boudreau et
al., 2009). There are no published data that indicate whether temporary
or permanent threshold shifts, auditory masking, or behavioral effects
occur in benthic invertebrates (Hawkins et al., 2014) and some studies
showed no short-term or long-term effects of air gun exposure (e.g.,
Andriguetto-Filho et al., 2005; Payne et al., 2007; 2008; Boudreau et
al., 2009). Exposure to air gun signals was found to significantly
increase mortality in scallops, in addition to causing significant
changes in behavioral patterns during exposure (Day et al., 2017).
However, the authors state that the observed levels of mortality were
not beyond naturally occurring rates. Explosions and pile driving could
potentially kill or injure nearby marine invertebrates; however,
mortality or long-term consequences for a few animals is unlikely to
have measurable effects on overall populations.
There is little information concerning potential impacts of noise
on zooplankton populations. However, one study (McCauley et al., 2017)
investigated zooplankton abundance, diversity, and mortality before and
after exposure to air gun noise, finding that the mortality rate for
zooplankton after air gun exposure was two to three times more compared
with controls for all taxa. The majority of taxa present were copepods
and cladocerans; for these taxa, the range within which effects on
abundance were detected was up to approximately 0.75 mi (1.2 km). In
order to have significant impacts on r-selected species (i.e., species
that produce a large number of offspring and contribute few resources
to each individual offspring) such as plankton, the spatial or temporal
scale of impact must be large in comparison with the ecosystem
concerned (McCauley et al., 2017).
Notably, a recently described study produced results inconsistent
with those of McCauley et al. (2017). Researchers conducted a field and
laboratory study to assess if exposure to air gun noise affects
mortality, predator escape response, or gene expression of the copepod
Calanus finmarchicus (Fields et al., 2019). Immediate mortality of
copepods was significantly higher, relative to controls, at distances
of 16.4 ft (5 m) or less from the air guns. Mortality one week after
the air gun blast was significantly higher in the copepods placed 32.8
ft (10 m) from the air gun but was not significantly different from the
controls at a distance of 65.6 ft (20 m) from the air gun. The increase
in mortality, relative to controls, did not exceed 30 percent at any
distance from the air gun. Moreover, the authors caution that even this
higher mortality in the immediate vicinity of the air guns may be more
pronounced than what would be observed in free-swimming animals due to
increased flow speed of fluid inside bags containing the experimental
animals. There were no sublethal effects on the escape performance or
the sensory threshold needed to initiate an escape response at any of
the distances from the air gun that were tested. Whereas McCauley et
al. (2017) reported an SEL of 156 dB at a range of 1,670-2,158.8 ft
(509-658 m), with zooplankton mortality observed at that range, Fields
et al. (2019) reported an SEL of 186 dB at a range of 82 ft (25 m),
with no reported mortality at that distance. The large scale of effect
observed here is of concern--particularly where repeated noise exposure
is expected--and further study is warranted.
Military expended materials resulting from training and testing
activities could potentially result in minor long-term changes to
benthic habitat; however, the impacts of small amount of expended
materials are unlikely to have measurable effects on overall
populations. Military expended materials may be colonized over time by
benthic organisms that prefer hard substrate and would provide
structure that could attract some species of fish or invertebrates.
Overall, the combined impacts of sound exposure, explosions, vessel
strikes, and military expended materials resulting from the proposed
activities would not be expected to have measurable effects on
populations of marine mammal prey species. Prey species exposed to
sound might move away from the sound source, experience TTS, experience
masking of biologically relevant sounds, or show no obvious direct
effects. Mortality from decompression injuries is possible in close
proximity to a sound, but only limited data on mortality in response to
air gun noise exposure are available (Fields et al., 2019, Hawkins et
al., 2014, McCauley et al., 2017). The most likely impacts for most
prey species in a given area would be temporary avoidance of the area.
Surveys using towed air gun arrays move through an area relatively
quickly, limiting exposure to multiple impulsive sounds. In all cases,
sound levels would return to ambient once a survey ends and the noise
source is shut down and, when exposure to sound ends, behavioral and/or
physiological responses are expected to end relatively quickly
(McCauley et al., 2000b). The duration of fish avoidance of a given
area after survey effort stops is unknown, but a rapid return to normal
recruitment, distribution, and behavior is anticipated. While the
potential for disruption of spawning aggregations or schools of
important prey species can be meaningful on a local scale, the mobile
and temporary nature of most surveys and the likelihood of temporary
avoidance behavior suggest that impacts would be minor. Long-term
consequences to marine invertebrate populations would not be expected
as a result of exposure to sounds or vessels in the HCTT Study Area.
Acoustic Habitat
Acoustic habitat is the soundscape which encompasses all of the
sound present in a particular location and time, as a whole when
considered from the perspective of the animals experiencing it. Animals
produce sound for, or listen for sounds produced by, conspecifics
(e.g., communication during feeding, mating, and other social
activities), other animals (e.g., finding prey or avoiding predators),
and the physical environment (e.g., finding suitable habitats,
navigating). Together, sounds made by animals and the geophysical
environment (e.g., produced by earthquakes, lightning, wind, rain,
waves) make up the natural contributions to the total acoustics of a
place. These acoustic conditions, termed acoustic habitat, are one
attribute of an animal's total habitat.
Soundscapes are also defined by, and acoustic habitat influenced
by, the total

[[Page 32208]]

contribution of anthropogenic sound. This may include incidental
emissions from sources such as vessel traffic or may be intentionally
introduced to the marine environment for data acquisition purposes
(e.g., the use of air gun arrays) or for military training and testing
purposes (e.g., the use of sonar and explosives and other acoustic
sources). Anthropogenic noise varies widely in its frequency, content,
duration, and SPL, and these characteristics greatly influence the
potential habitat-mediated effects to marine mammals (please also see
the previous discussion in the Masking section), which may range from
local effects for brief periods of time to chronic effects over large
areas and for long durations. Depending on the extent of effects to
habitat, animals may alter their communications signals (thereby
potentially expending additional energy) or miss acoustic cues (either
conspecific or adventitious). Problems arising from a failure to detect
cues are more likely to occur when noise stimuli are chronic and
overlap with biologically relevant cues used for communication,
orientation, and predator/prey detection (Francis and Barber, 2013).
For more detail on these concepts see, e.g., Barber et al., 2009;
Pijanowski et al., 2011; Lillis et al., 2014.
The term ``listening area'' refers to the region of ocean over
which sources of sound can be detected by an animal at the center of
the space. Loss of communication space concerns the area over which a
specific animal signal (used to communicate with conspecifics in
biologically important contexts such as foraging or mating) can be
heard, in noisier relative to quieter conditions (Clark et al., 2009).
Lost listening area concerns the more generalized contraction of the
range over which animals would be able to detect a variety of signals
of biological importance, including eavesdropping on predators and prey
(Barber et al., 2009). Such metrics do not, in and of themselves,
document fitness consequences for the marine animals that live in
chronically noisy environments. Long-term population-level consequences
mediated through changes in the ultimate survival and reproductive
success of individuals are difficult to study, and particularly so
underwater. However, it is increasingly well documented that aquatic
species rely on qualities of natural acoustic habitats, with
researchers quantifying reduced detection of important ecological cues
(e.g., Francis and Barber, 2013; Slabbekoorn et al., 2010) as well as
survivorship consequences in several species (e.g., Simpson et al.,
2015; Nedelec et al., 2015).
The sounds produced during training and testing activities can be
widely dispersed or concentrated in small areas for varying periods.
Sound produced from training and testing activities in the HCTT Study
Area is temporary and transitory. Any anthropogenic noise attributed to
training and testing activities in the HCTT Study Area would be
temporary and the affected area would be expected to immediately return
to the original state when these activities cease.
Water Quality
Training and testing activities may introduce constituents into the
water column. Based on the analysis of the 2024 HCTT Draft EIS/OEIS,
military expended materials (e.g., undetonated explosive materials)
would be released in quantities and at rates that would not result in a
violation of any water quality standard or criteria. NMFS has reviewed
this analysis and concurs that it reflects the best available science.
High-order explosions consume most of the explosive material, creating
typical combustion products. For example, in the case of Royal
Demolition Explosive, 98 percent of the products are common seawater
constituents and the remainder is rapidly diluted below threshold
effect level. Explosion by-products associated with high order
detonations present no secondary stressors to marine mammals through
sediment or water. However, low order detonations and unexploded
ordnance present elevated likelihood of impacts on marine mammals.
Indirect effects of explosives and unexploded ordnance to marine
mammals via sediment is possible in the immediate vicinity of the
ordnance. Degradation products of Royal Demolition Explosive are not
toxic to marine organisms at realistic exposure levels (Rosen and
Lotufo, 2010). Relatively low solubility of most explosives and their
degradation products means that concentrations of these contaminants in
the marine environment are relatively low and readily diluted.
Furthermore, while explosives and their degradation products were
detectable in marine sediment approximately 6-12 inches (0.15-0.3 m)
away from degrading ordnance, the concentrations of these compounds
were not statistically distinguishable from background beyond 3-6 ft
(1-2 m) from the degrading ordnance. Taken together, it is possible
that marine mammals could be exposed to degrading explosives, but it
would be within a very small radius of the explosive (1-6 ft (0.3-2
m)).
Equipment used by the Action Proponents within the HCTT Study Area,
including ships and other marine vessels, aircraft, and other
equipment, are also potential sources of by-products. All equipment is
properly maintained in accordance with applicable Navy, Coast Guard,
Army, and legal requirements. All such operating equipment meets
Federal water quality standards, where applicable.

Estimated Take of Marine Mammals

This section indicates the number of takes that NMFS is proposing
to authorize, which is based on the amount of take that NMFS
anticipates is reasonably likely to occur. NMFS coordinated closely
with the Action Proponents in the development of their incidental take
application, and preliminarily agrees that the methods the Action
Proponents have put forth described herein to estimate take (including
the model, thresholds, and density estimates), and the resulting
numbers are based on the best available science and appropriate for
authorization.
Takes would be predominantly in the form of harassment, but a
limited number of mortalities are also possible. For this military
readiness activity, the MMPA defines ``harassment'' as (1) any act that
injures or has the significant potential to injure a marine mammal or
marine mammal stock in the wild (Level A harassment); or (2) any act
that disturbs or is likely to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of natural behavioral patterns,
including, but not limited to, migration, surfacing, nursing, breeding,
feeding, or sheltering, to a point where the behavioral patterns are
abandoned or significantly altered (Level B harassment) (16 U.S.C.
1362(18)(B)).
Proposed authorized takes would primarily be in the form of Level B
harassment, as use of the acoustic (e.g., active sonar, pile driving,
and seismic air guns) and explosive sources and missile launches is
most likely to result in disruption of natural behavioral patterns to a
point where they are abandoned or significantly altered (as defined
specifically at the beginning of this section, but referred to
generally as behavioral disturbance) for marine mammals, either via
direct behavioral disturbance or TTS. There is also the potential for
Level A harassment, in the form of auditory injury to result from
exposure to the sound sources utilized in military readiness
activities. Lastly, no more than 7 serious injuries or mortalities
total (over the 7-year period)

[[Page 32209]]

of large whales could potentially occur through vessel strikes, and 40
serious injuries or mortalities (over the 7-year period) from explosive
use. Although we analyze the impacts of these potential serious
injuries or mortalities that are proposed for authorization, the
proposed mitigation and monitoring measures are expected to minimize
the likelihood (i.e., further lower the already low probability) that
vessel strike (and the associated serious injury or mortality) would
occur, as well as the severity of other takes.
Generally speaking, for acoustic impacts NMFS estimates the amount
and type of harassment by considering: (1) acoustic thresholds above
which NMFS believes the best available science indicates marine mammals
would experience behavioral disturbance or incur some degree of
temporary or permanent hearing impairment; (2) the area or volume of
water that would be ensonified above these levels in a day or event;
(3) the density or occurrence of marine mammals within these ensonified
areas; and (4) the number of days of activities or events.

Acoustic Thresholds

Using the best available science, NMFS, in coordination with the
Navy, has established acoustic thresholds that identify the most
appropriate received level of underwater sound above which marine
mammals exposed to these sound sources could be reasonably expected to
directly incur a disruption in behavior patterns to a point where they
are abandoned or significantly altered (equated to onset of Level B
harassment), or to incur TTS onset (equated to Level B harassment via
the indirect disruptions of behavioral patterns) or AUD INJ onset
(equated to Level A harassment). Thresholds have also been developed to
identify the pressure and impulse levels above which animals may incur
non-auditory injury or mortality from exposure to explosive detonation.
Hearing Impairment (TTS/AUD INJ), Non-Auditory Injury, and Mortality
NMFS' 2024 Technical Guidance (NMFS, 2024) identifies dual criteria
to assess AUD INJ (Level A harassment) to five different marine mammal
groups (based on hearing sensitivity) as a result of exposure to noise
from two different types of sources (impulsive or non-impulsive). The
Updated Technical Guidance also identifies criteria to predict TTS,
which is not considered injury and falls into the Level B harassment
category. The Action Proponents' specified activities include the use
of non-impulsive (i.e., sonar, vibratory pile driving) and impulsive
(i.e., explosives, air guns, impact pile driving) sources.
For the consideration of impacts on hearing in Phase IV, marine
mammals were divided into nine groups for analysis: VLF, LF, HF, VHF,
SI, PCW and PCA, and OCW and OCA. For each group, a frequency-dependent
weighting function and numeric thresholds for the onset of TTS and the
onset of AUD INJ were estimated. The onset of TTS is defined as a TTS
of 6 dB measured approximately 2-5 minutes after exposure. A TTS of 40
dB is used as a proxy for the onset of AUD INJ (i.e., it is assumed
that exposures beyond those capable of causing 40 dB of TTS have the
potential to result in PTS or other auditory injury (e.g., loss of
cochlear neuron synapses)). Exposures just sufficient to cause TTS or
AUD INJ are denoted as ``TTS onset'' or ``AUD INJ onset'' exposures.
Onset levels are treated as step functions or ``all-or-nothing''
thresholds: exposures above the TTS or AUD INJ onset level are assumed
to always result in TTS or AUD INJ, while exposures below the TTS or
AUD INJ onset level are assumed to not cause TTS or AUD INJ. For non-
impulsive exposures, onset levels are specified in frequency-weighted
sound exposure level (SEL); for impulsive exposures, dual metrics of
weighted SEL and unweighted peak sound pressure level (SPL) are used.
To compare Phase IV weighting functions and TTS/AUD INJ SEL
thresholds to those used in Phase III, both the weighting function
shape and the weighted threshold values were considered; the weighted
thresholds by themselves only indicate the TTS/AUD INJ threshold at the
most susceptible frequency (based on the relevant weighting function).
In contrast, the TTS/AUD INJ exposure functions incorporate both the
shape of the weighting function and the weighted threshold value and
provide the best means of comparing the frequency-dependent TTS/AUD INJ
thresholds for Phase III and Phase IV.
The most significant differences between the Phase III and Phase IV
functions and thresholds include the following:
Mysticetes were divided into two groups (VLF and LF), with
the upper hearing limit for the LF group increased from Phase III to
match recent hearing measurements in minke whales (Houser et al.,
2024);
Group names were changed from Phase III to be consistent
with Southall et al. (2019). Specifically, the Phase III mid-frequency
(MF) cetacean group is now designated as the high-frequency (HF)
cetacean group, and the group previously designated as high-frequency
(HF) cetaceans is now the very-high frequency (VHF) cetacean group;
For the HF group, Phase IV onset TTS/AUD INJ thresholds
are lower compared to Phase III at frequencies below approximately 10
kHz. This is a result of new TTS onset data for dolphins at low
frequencies (Finneran et al., 2023);
For the PCW group, new TTS data for harbor seals
(Kastelein et al., 2020a; Kastelein et al., 2020b) resulted in slightly
lower TTS/AUD INJ thresholds at high frequencies compared to Phase III;
and
For group OCW, new TTS data for California sea lions
(Kastelein et al., 2021b; Kastelein et al., 2022a, 2022b) resulted in
significantly lower TTS/AUD INJ thresholds compared to Phase III.
Of note, the thresholds and weighting function for the LF cetacean
hearing group in NMFS' 2024 Technical Guidance (NMFS, 2024) match the
Navy's VLF cetacean hearing group. However, the weighting function for
those hearing groups differs between the two documents (i.e., the
Navy's LF cetacean group has a different weighting function from NMFS)
due to the Houser et al. (2024) minke whale data incorporated into Navy
2024, but not NMFS (2024). While NMFS' 2024 Technical Guidance differs
from the criteria that the Action Proponents used to assess AUD INJ and
TTS for low-frequency cetaceans, NMFS concurs that the criteria the
Action Proponents applied are appropriate for assessing the impacts of
their proposed action. The criteria used by the Action Proponents are
conservative in that those criteria show greater sensitivity at higher
frequencies (i.e., application of those criteria result in a higher
amount of estimated take by higher frequency sonars than would result
from application of NMFS' 2024 Technical Guidance) which is where more
of the take is expected.
These thresholds (table 18 and table 19) were developed by
compiling and synthesizing the best available science and soliciting
input multiple times from both public and peer reviewers. The
references, analysis, and methodology used in the development of the
thresholds are described in Updated Technical Guidance, which may be
accessed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 32210]]

Table 18--Acoustic Thresholds Identifying the Onset of TTS
----------------------------------------------------------------------------------------------------------------
TTS threshold SEL AUD INJ threshold SEL
Group (weighted) (weighted)
----------------------------------------------------------------------------------------------------------------
Very low-frequency (VLF)....................................... 177 197
Low-frequency (LF)............................................. 177 197
High-frequency (HF)............................................ 181 201
Very high-frequency (VHF)...................................... 161 181
Phocid carnivores in water (PW)................................ 175 195
Otariid carnivores in water (OW)............................... 179 199
Phocid carnivores in air (PA).................................. 134 154
Otariid carnivores in air (OA)................................. 157 177
----------------------------------------------------------------------------------------------------------------
Note: SEL thresholds in dB re 1 [mu]Pa\2\ s underwater and dB re 20 [mu]Pa\2\ s in air.

Based on the best available science, the Action Proponents (in
coordination with NMFS) used the acoustic and pressure thresholds
indicated in table 18 to predict the onset of behavioral harassment,
AUD INJ, TTS, tissue damage, and mortality due to explosive sources.
For explosive activities using single detonations (i.e., no more
than one detonation within a day), such as those described in the
proposed activity, NMFS uses TTS onset thresholds to assess the
likelihood of behavioral harassment, rather than the Level B harassment
threshold for multiple detonations indicated in table 19. While marine
mammals may also respond to single explosive detonations, these
responses are expected to more typically be in the form of startle
response, rather than a more meaningful disruption of a behavioral
pattern. On the rare occasion that a single detonation might result in
a behavioral response that qualifies as Level B harassment, it would be
expected to be in response to a comparatively higher received level.
Accordingly, NMFS considers the potential for these responses to be
quantitatively accounted for through the application of the TTS
criteria, which, as noted above, is 5 dB higher than the behavioral
harassment threshold for multiple explosives.

Table 19--Explosive Thresholds for Marine Mammals for AUD INJ, TTS, and Behavior
[Multiple detonations]
----------------------------------------------------------------------------------------------------------------
AUD INJ impulsive TTS impulsive Behavioral threshold (multiple
Hearing group threshold * threshold * detonations)
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans... Cell 1: Lp,0- Cell 2: Lp,0- Cell 3: LE,LF,24h: 163 dB.
pk,flat: 222 dB; pk,flat: 216 dB;
LE,p,LF,24h: 183 LE,LF,24h: 168 dB.
dB.
High-Frequency (HF) Cetaceans.. Cell 4: Lp,0- Cell 5: Lp,0- Cell 6: LE,HF,24h: 173 dB.
pk,flat: 230 dB; pk,flat: 224 dB;
LE,p,HF,24h: 193 LE,HF,24h: 178 dB.
dB.
Very High-Frequency (VHF) Cell 7: Lp,0- Cell 8: Lp,0- Cell 9: LE,VHF,24h: 139 dB.
Cetaceans. pk,flat: 202 dB; pk,flat: 196 dB;
LE,p,VHF,24h: 159 LE,VHF,24h: 144
dB. dB.
Phocid Pinnipeds (PW) Cell 10: Lp,0- Cell 11: Lp,0- Cell 12: LE,PW,24h: 163 dB.
(Underwater). pk,flat: 223 dB; pk,flat: 217 dB;
LE,p,PW,24h: 183 LE,PW,24h: 168 dB.
dB.
Otariid Pinnipeds (OW) Cell 13: Lp,0- Cell 14: Lp,0- Cell 15: LE,OW,24h: 165 dB.
(Underwater). pk,flat: 230 dB; pk,flat: 224 dB;
LE,p,OW,24h: 185 LE,OW,24h: 170 dB.
dB.
Phocid Pinnipeds (PA) (In-Air). Cell 16: Lp,0- Cell 17: Lp,0- Cell 18: N/A.
pk,flat: 162 dB; pk,flat: 156 dB;
LE,p,PA,24h: 140 LE,PA,24h: 125 dB.
dB.
Otariid Pinnipeds (OA) (In-Air) Cell 19: Lp,0- Cell 20: Lp,0- Cell 21: N/A.
pk,flat : 177 dB; pk,flat: 171 dB;
LE,p,OA,24h: 163 LE,OA,24h: 148 dB.
dB.
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and
weighted cumulative sound exposure level (LE,p) has a reference value of 1 [micro]Pa\2\s. In this table,
criteria are abbreviated to be more reflective of International Organization for Standardization standards
(ISO, 2017; ISO, 2020). The subscript ``flat'' is being included to indicate peak sound pressure are flat
weighted or unweighted within the generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165
kHz) or in air (i.e., 42 Hz to 52 kHz). The subscript associated with cumulative sound exposure level criteria
indicates the designated marine mammal auditory weighting function (LF, HF, and VHF cetaceans, and PW and OW
pinnipeds) and that the recommended accumulation period is 24 hours. The weighted cumulative sound exposure
level criteria could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty
cycle). When possible, it is valuable for action proponents to indicate the conditions under which these
criteria will be exceeded.
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.

The criterion for mortality is based on severe lung injury observed
in terrestrial mammals exposed to underwater explosions as recorded in
Goertner (1982). The criteria for non-auditory injury are based on
slight lung injury or gastrointestinal (commonly referred to as G.I.)
tract injury observed in the same data set. Mortality and slight lung
injury impacts to marine mammals are estimated using impulse thresholds
based on both calf/pup/juvenile and adult masses (see the Criteria and
Thresholds Technical Report). The peak pressure threshold applies to
all species and age classes. Unlike the prior analysis (Phase III),
this analysis relies on the onset rather than the mean estimated
threshold for these effects. This revision results in a small increase
in the predicted non-auditory injuries and mortalities for the same
event versus prior analyses. Thresholds are provided in table 20 for
use in non-auditory injury assessment for marine mammals exposed to
underwater explosives. Of note, non-auditory injury and mortality from
land-based missile and target launches are so unlikely as to

[[Page 32211]]

be discountable under normal conditions.

Table 20--Non-Auditory Injury Thresholds for Underwater Explosives
----------------------------------------------------------------------------------------------------------------
Hearing group Mortality--impulse * Injury--impulse * Injury--peak pressure
----------------------------------------------------------------------------------------------------------------
All Marine Mammals.................. Cell 1: Modified Goertner Cell 2: Modified Cell 3: Lp0-pk,flat:
model; Equation 1. Goertner model; 237 dB.
Equation 2.
----------------------------------------------------------------------------------------------------------------
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa. In this table, thresholds are abbreviated
to reflect ANSI (2013). However, ANSI defines peak sound pressure as incorporating frequency weighting, which
is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is being included to indicate
peak sound pressure should be flat weighted or unweighted within the overall marine mammal generalized hearing
range.
* Lung injury (severe and slight) thresholds are dependent on animal mass (Recommendation: table C.9 from U.S.
Department of the Navy (2017a) based on adult and/or calf/pup mass by species).
Modified Goertner Equations for severe and slight lung injury (pascal-second)
Equation 1: 103M\1/3\(1 + D/10.1)\1/6\ Pa-s
Equation 2: 47.5M\1/3\(1 + D/10.1)\1/6\ Pa-s
M animal (adult and/or calf/pup) mass (kg) (table C.9 in DoN 2017)
D animal depth (meters).

Level B Harassment by Behavioral Disturbance
Though significantly driven by received level and distance, the
onset of Level B harassment by behavioral disturbance from
anthropogenic noise exposure is also informed to varying degrees by
other factors and can be difficult to predict (Southall et al., 2007;
Ellison et al., 2012). As discussed in the Potential Effects of
Specified Activities on Marine Mammals and Their Habitat section,
marine mammal responses to sound (some of which are considered
disturbances that qualify as take under the MMPA) are highly variable
and context specific (i.e., they are affected by differences in
acoustic conditions; differences between species and populations;
differences in gender, age, reproductive status, or social behavior;
and other prior experience of the individuals). This means there is
support for considering alternative approaches for estimating Level B
behavioral harassment.
Despite the rapidly evolving science, there are still challenges in
quantifying expected behavioral responses that qualify as take by Level
B harassment, especially where the goal is to use one or two
predictable indicators (e.g., received level and distance) to predict
responses that are also driven by additional factors that cannot be
easily incorporated into the thresholds (e.g., context). So, while the
criteria that identify Level B harassment by behavioral disturbance
(referred to as ``behavioral harassment thresholds'') have been refined
to better consider the best available science (e.g., incorporating both
received level and distance), they also still have some built-in
factors to address the challenge noted. For example, while duration of
observed responses in the data are now considered in the thresholds,
some of the responses that are informing take thresholds are of a very
short duration, such that it is possible some of these responses might
not always rise to the level of disrupting behavior patterns to a point
where they are abandoned or significantly altered. We describe the
application of this behavioral harassment threshold as identifying the
maximum number of instances in which marine mammals could be reasonably
expected to experience a disruption in behavior patterns to a point
where they are abandoned or significantly altered. In summary, we
believe these behavioral harassment criteria are the most appropriate
method for predicting Level B harassment by behavioral disturbance
given the best available science and the associated uncertainty.
Sonar--
In its analysis of impacts associated with sonar acoustic sources
(which was coordinated with NMFS), the Action Proponents used an
updated approach, as described below. Many of the behavioral responses
identified using the Action Proponents' quantitative analysis are most
likely to be of moderate severity as described in the Southall et al.
(2021) behavioral response severity scale. These ``moderate'' severity
responses were considered significant if they were sustained for the
duration of the exposure or longer. Within the Action Proponents'
quantitative analysis, many responses are predicted from exposure to
sound that may exceed an animal's Level B behavioral harassment
threshold for only a single exposure (lasting a few seconds) to several
minutes, and it is likely that some of the resulting estimated
behavioral responses that are counted as Level B harassment would not
constitute ``significantly altering or abandoning natural behavioral
patterns'' (i.e., the estimated number of takes by Level B harassment
due to behavioral disturbance and response is likely somewhat of an
overestimate).
As noted above, the Action Proponents coordinated with NMFS to
develop behavioral harassment thresholds specific to their military
readiness activities utilizing active sonar that identify at what
received level and distance Level B harassment by behavioral
disturbance would be expected to result. These behavioral harassment
thresholds consist of behavioral response functions (BRFs) and
associated distance cut-off conditions, and are also referred to,
together, as ``the criteria.'' These criteria are used to estimate the
number of animals that may exhibit a behavioral response that qualifies
as take under the MMPA when exposed to sonar and other transducers. The
way the criteria were derived is discussed in detail in the Criteria
and Thresholds Technical Report. Developing these behavioral harassment
criteria involved multiple steps. All peer-reviewed published
behavioral response studies conducted both in the field and on captive
animals were examined in order to understand the breadth of behavioral
responses of marine mammals to sonar and other transducers. Marine
mammals were divided into four groups for analysis: mysticetes (all
baleen whales); odontocetes (most toothed whales, dolphins, and
porpoises); sensitive species (beaked whales and harbor porpoise); and
pinnipeds and other marine carnivores (true seals, sea lions, walruses,
sea otters, polar bears). These groups are like the groups used in the
behavioral response analysis (Phase III), with the exception of
combining beaked whales and harbor porpoise into a single curve. For
each group, a biphasic BRF was developed using the best available data
and Bayesian dose response models

[[Page 32212]]

developed at the University of St. Andrews. The BRF base probability of
response on the highest SPL (RMS) received level.
The analysis of BRFs differs from the previous phase (Phase III)
due to the addition of new data and the separation of some species
groups. Figure 10 in the Criteria and Thresholds Technical Report
indicates the changes in BRFs from Phase III to Phase IV. The sensitive
species BRF is more sensitive at lower received levels but less
sensitive at higher received levels than the prior beaked whale and
harbor porpoise functions. The odontocete BRF is less sensitive overall
due to additional behavioral response research, which will result in a
lower number of behavioral responses than in the prior analysis for the
same event, but also reduces the avoidance of auditory effects. The
pinnipeds (in-water) BRF is more sensitive due to the inclusion of
additional captive pinniped data (only three behavioral studies using
captive pinnipeds were available for the derivation of the BRF).
Behavioral studies of captive animals can be difficult to extrapolate
to wild animals due to several factors (e.g., use of trained subjects).
This means the pinniped BRF likely overestimates effects compared to
observed responses of wild pinnipeds to sound and anthropogenic
activity. The mysticete BRF is less sensitive across most received
levels due to including additional behavioral response research. This
will result in a lower number of behavioral responses than in the prior
analysis for the same event, but also reduces the avoidance of auditory
effects.
The BRFs only relate the highest received level of sound to the
probability that an animal will have a behavioral response. The BRFs do
not account for the duration or pattern of use of any individual sound
source or of the activity as a whole, the number of sound sources that
may be operating simultaneously, or how loud the animal may perceive
the sonar signal to be based on the frequency of the sonar versus the
animal's hearing range.
Criteria for assessing marine mammal behavioral responses to sonars
use the metric of highest received sound level (RMS) to evaluate the
risk of immediate responses by exposed animals. Currently, there are
limited data to develop criteria that include the context of an
exposure, characteristics of individual animals, behavioral state,
duration of an exposure, sound source duty cycle, and the number of
individual sources in an activity (although these factors certainly
influence the severity of a behavioral response) and, further, even
where certain contextual factors may be predictive where known, it is
difficult to reliably predict when such factors will be present.
The BRFs also do not account for distance. At moderate to low
received levels the correlation between probability of response and
received level is very poor and it appears that other variables mediate
behavioral responses (e.g., Ellison et al., 2012) such as the distance
between the animal and the sound source. For this analysis, distance
between the animal and the sound source (i.e., range) was initially
included, however, range was too confounded with received level and
therefore did not provide additional information about the possibility
of response.
Data suggest that beyond a certain distance, significant behavioral
responses are unlikely. At shorter ranges (less than 10 km) some
behavioral responses have been observed at received levels below 140 dB
re 1 [mu]Pa. Thus, proximity may mediate behavioral responses at lower
received levels. Since most data used to derive the BRFs are within 10
km of the source, probability of response at farther ranges is not
well-represented. Therefore, the source-receiver range must be
considered separately to estimate likely significant behavioral
responses.
This analysis applies behavioral cut-off conditions to responses
predicted using the BRFs. Animals within a specified distance and above
a minimum probability of response are assumed to have a significant
behavioral response. The cut-off distance is based on the farthest
source-animal distance across all known studies where animals exhibited
a significant behavioral response. Animals beyond the cut-off distance
but with received levels above the sound pressure level associated with
a probability of response of 0.50 on the BRF are also assumed to have a
significant behavioral response. The actual likelihood of significant
behavioral responses occurring beyond the distance cut-off is unknown.
Significant behavioral responses beyond 100 km are unlikely based on
source-animal distance and attenuated received levels. The behavioral
cut-off conditions and additional information on the derivation of the
cut-off conditions can be found in table 2.2-3 of the Criteria and
Thresholds Technical Report.
The Action Proponents used cutoff distances beyond which the
potential of significant behavioral responses (and therefore Level B
harassment) is considered to be unlikely (see table 21). These
distances were determined by examining all available published field
observations of behavioral responses to sonar or sonar-like signals
that included the distance between the sound source and the marine
mammal. Behavioral effects calculations are based on the maximum SPL to
which a modeled marine mammal is exposed. There is empirical evidence
to suggest that animals are more likely to exhibit significant
behavioral responses to moderate levels sounds that are closer and less
likely to exhibit behavioral responses when exposed to moderate levels
of sound from a source that is far away. To account for this, the
Action Proponents have implemented behavioral cutoffs that consider
both received sound level and distance from the source. These updated
cutoffs conditions are unique to each behavioral hearing group and are
outlined in table 21.

Table 21--Behavioral Cut-Off Conditions for Each Behavioral Hearing Group
----------------------------------------------------------------------------------------------------------------
Received level associated with p(0.50) on the Cut-off range
Behavioral group behavioral response function (dB RMS) (km)
----------------------------------------------------------------------------------------------------------------
Sensitive Species............................... 133 40
Odontocetes..................................... 168 15
Mysticetes...................................... 185 10
Pinnipeds....................................... 156 5
----------------------------------------------------------------------------------------------------------------
Note: Sensitive Species includes beaked whales and harbor porpoises.

[[Page 32213]]

The Action Proponents and NMFS have used the best available science
to address the challenging differentiation between significant and non-
significant behavioral responses (i.e., whether the behavior has been
abandoned or significantly altered such that it qualifies as
harassment), but have erred on the cautious side where uncertainty
exists (e.g., counting these lower duration responses as take), which
likely results in some degree of overestimation of Level B harassment
by behavioral disturbance. We consider application of these behavioral
harassment thresholds, therefore, as identifying the maximum number of
instances in which marine mammals could be reasonably expected to
experience a disruption in behavior patterns to a point where they are
abandoned or significantly altered (i.e., Level B harassment). NMFS has
carefully reviewed the criteria (i.e., BRFs and cutoff distances for
the species), and agrees that it is the best available science and is
the appropriate method to use at this time for determining impacts to
marine mammals from military sonar and other transducers and for
calculating take and to support the determinations made in this
proposed rule. Because this is the most appropriate method for
estimating Level B harassment given the best available science and
uncertainty on the topic, it is these numbers of Level B harassment by
behavioral disturbance that are analyzed in the Preliminary Analysis
and Negligible Impact Determination section and would be authorized.
Air Guns, Pile Driving, and Explosives--
Based on what the available science indicates and the practical
need to use a threshold based on a factor that is both predictable and
measurable for most activities, NMFS uses generalized acoustic
thresholds based on received level to estimate the onset of behavioral
harassment for sources other than active sonar. NMFS predicts that
marine mammals are likely to be behaviorally harassed in a manner we
consider Level B harassment when exposed to underwater anthropogenic
noise above received levels of 120 dB re 1 [mu]Pa (RMS) for continuous
(e.g., vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa
(RMS) for non-explosive impulsive (e.g., seismic air guns) or
intermittent (e.g., scientific sonar) sources. For the Action
Proponents' activities, to estimate behavioral effects from air guns,
the threshold of 160 dB re 1 [micro]Pa (RMS) is used and the root mean
square calculation for air guns is based on the duration defined by 90
percent of the cumulative energy in the impulse. The indicated
thresholds were also applied to estimate behavioral effects from impact
and vibratory pile driving (see table 22). These thresholds are the
same as those applied in the prior analysis (Phase III) of these
stressors in the Study Area, although the explosive behavioral
threshold has shifted, corresponding to changes in the TTS thresholds.

Table 22--Behavioral Response Thresholds for Air Guns, Pile Driving, and
Explosives
------------------------------------------------------------------------
Sound source Behavioral threshold
------------------------------------------------------------------------
Air gun................................ 160 dB RMS re 1 [mu]Pa SPL.
Impact pile driving.................... 160 dB RMS re 1 [mu]Pa SPL.
Vibratory pile driving................. 120 dB RMS re 1 [mu]Pa SPL.
Single explosion (underwater).......... TTS onset threshold (weighted
SEL).
Multiple explosions (underwater)....... 5 dB less than the TTS onset
threshold (weighted SEL).
Explosion in Air *..................... 100 dB 20 [mu]Pa (otariid and
phocid).
------------------------------------------------------------------------
* Estimated takes from land-based missile and rocket launches are based
on pinniped observations during prior activities rather than in-air
thresholds.

While the best available science for assessing behavioral responses
of marine mammals to impulsive sounds relies on data from seismic and
pile driving sources, it is likely that these predicted responses using
a threshold based on seismic and pile driving represent a worst-case
scenario compared to behavioral responses to explosives used in
military readiness activities, which would typically consist of single
impulses or a cluster of impulses rather than long-duration, repeated
impulses (e.g., large-scale air gun arrays).
For single explosions at received sound levels below hearing loss
thresholds, the most likely behavioral response is a brief alerting or
orienting response. Since no further sounds follow the initial brief
impulses, significant behavioral responses would not be expected to
occur. If a significant response were to occur, the Action Proponents'
analysis assumes it would be as a result of an exposure at levels
within the range of auditory impacts (TTS and AUD INJ). Because of this
approach, the number of auditory impacts is higher than the number of
behavioral impacts in the quantified results for some stocks.
If more than one explosive event occurs within any given 24-hour
period during a military readiness activity, behavioral disturbance is
considered more likely to occur and specific criteria are applied to
predict the number of animals that may have a behavioral response. For
events with multiple explosions, the behavioral threshold used in this
analysis is 5 dB less than the TTS onset threshold. This value is
derived from observed onsets of behavioral response by test subjects
(bottlenose dolphins) during non-impulse TTS testing (Schlundt et al.,
2000).

Navy Acoustic Effects Model

The Navy Acoustic Effects Model (NAEMO) is their standard model for
assessing acoustic effects on marine mammals. NAEMO calculates sound
energy propagation from sonar and other transducers, air guns, and
explosives during military readiness activities and the sound received
by animat dosimeters. Animat dosimeters are virtual representations of
marine mammals distributed in the area around the modeled activity and
each dosimeter records its individual sound ``dose.'' The model bases
the distribution of animats over the HCTT Study Area on the density
values in the Navy Marine Species Density Database (NMSDD) and
distributes animats in the water column proportional to the known time
that species spend at varying depths.
The model accounts for environmental variability of sound
propagation in both distance and depth when computing the sound level
received by the animats. The model conducts a statistical analysis
based on multiple model runs to compute the estimated effects on
animals. The number of animats that exceed the thresholds for effects
is tallied to provide an estimate of the number of marine mammals that
could be affected.

[[Page 32214]]

Assumptions in NAEMO intentionally err on the side of
overestimation when there are unknowns. The specified activities are
modeled as though they would occur regardless of proximity to marine
mammals, meaning that the implementation of power downs or shutdowns
are not modeled or, thereby, considered in the take estimates. For more
information on this process, see the discussion in the Estimated Take
from Acoustic Stressors section below. Many explosions from ordnance
such as bombs and missiles actually occur upon impact with above-water
targets. However, for this analysis, sources such as these were modeled
as exploding underwater. This overestimates the amount of explosive and
acoustic energy entering the water.
The model estimates the acoustic impacts caused by sonars and other
transducers, explosives, and air guns during individual military
readiness activities. During any individual modeled event, impacts to
individual animats are considered over 24-hour periods. The animats do
not represent actual animals, but rather they represent a distribution
of animals based on density and abundance data, which allows for a
statistical analysis of the number of instances that marine mammals may
be exposed to sound levels resulting in an effect. Therefore, the model
estimates the number of instances in which an effect threshold was
exceeded over the course of a year, but does not estimate the number of
individual marine mammals that may be impacted over a year (i.e., some
marine mammals could be impacted several times, while others would not
experience any impact). A detailed explanation of NAEMO is provided in
the Acoustic Impacts Technical Report.
As NAEMO interrogates the simulation data in the Animat Processor,
exposures that are both outside the distance cutoff and below the
received level cutoff are omitted when determining the maximum SPL for
each animat. This differs from Phase III, in which only distance
cutoffs were applied, meaning that all exposures outside the distance
cutoffs were omitted, with no consideration of received level.
The presence of the two cutoff criteria in Phase IV provides a more
accurate and conservative estimation of behavioral effects because
louder exposures that would have been omitted previously, when only a
distance cutoff was applied, are considered in Phase IV, while the
estimation of behavioral effects still omits exposures at distances and
received levels that would be unlikely to produce a significant
behavioral response. NAEMO retains the capability of calculating
behavioral effects without the cutoffs applied, depending on user
preference.
The impulsive behavioral criteria are not based on the probability
of a behavioral response but rather on a single SPL metric. For
consideration of impulsive behavioral effects, the cutoff conditions in
table 21 are not applied.
Pile Driving
The Action Proponents performed a quantitative analysis without
NAEMO to estimate the number of times marine mammals could be affected
by pile driving and extraction used during port damage repair
activities at Port Hueneme. The analysis considered details of the
activity, sound exposure criteria, and the number and distribution of
marine mammals. This information was then used in an ``area*density''
model in which the areas within each footprint (i.e., harassment zone)
that encompassed a potential effect were calculated for a given day's
activities. The effects analyzed included behavioral response, TTS, and
AUD INJ for marine mammals.
Then, these areas were multiplied by the density of each marine
species within the Port Hueneme area (California sea lion and harbor
seal) to estimate the number of effects. Uniform density values for
species expected to be present in the nearshore areas where pile
driving could occur were estimated using the NMSDD or available survey
data specific to the activity location. More detail is provided in the
2024 HCTT Draft EIS/OEIS. Since the same animal can be ``taken'' every
day (i.e., 24-hour reset time), the number of predicted effects from a
given day were multiplied by the number of days for that activity. This
generated a total estimated number of effects over the entire activity,
which was then multiplied by the maximum number of times per year this
activity could happen. The result was the estimated effects per species
and stock in a year.

Range to Effects

This section provides range (distance) to effects for sonar and
other active acoustic sources as well as explosives to specific
acoustic thresholds determined using NAEMO. Ranges are determined by
modeling the distance that noise from a source will need to propagate
to reach exposure level thresholds specific to a hearing group that
will cause behavioral response, TTS, AUD INJ, non-auditory injury, and
mortality. Ranges to effects (table 23 through table 36) are utilized
to help predict impacts from acoustic and explosive sources and assess
the benefit of mitigation zones. Marine mammals exposed within these
ranges for the shown duration are predicted to experience the
associated effect. Range to effects is important information in not
only predicting acoustic impacts, but also in verifying the accuracy of
model results against real-world situations and determining adequate
mitigation ranges to avoid higher level effects, especially
physiological effects to marine mammals.
Sonar
Ranges to effects for sonar were determined by modeling the
distance that sound would need to propagate to reach exposure level
thresholds specific to a hearing group that would cause behavioral
response, TTS, and AUD INJ, as described in the Criteria and Thresholds
Technical Report. The ranges do not account for an animal avoiding a
source nor for the movement of the platform, both of which would
influence the actual range to onset of auditory effects during an
actual exposure.
Table 23 through table 28 below provide the ranges to TTS and AUD
INJ for marine mammals from exposure durations of 1, 30, 60, and 120
seconds (s) for six sonar systems proposed for use (see also appendix A
of the application). Due to the lower acoustic thresholds for TTS
versus AUD INJ, ranges to TTS are larger. Successive pings can be
expected to add together, further increasing the range to the onset of
TTS and AUD INJ.

Table 23--Very Low-Frequency Cetacean Ranges to Effects for Sonar
----------------------------------------------------------------------------------------------------------------
Duration
Sonar type Depth (m) (s) Range to TTS (SD) Range to AUD INJ (SD)
----------------------------------------------------------------------------------------------------------------
Dipping sonar....................... <=200 1 160 m (30 m)........... 12 m (4 m).
Dipping sonar....................... <=200 30 312 m (75 m)........... 21 m (6 m).
Dipping sonar....................... <=200 60 423 m (97 m)........... 25 m (5 m).

[[Page 32215]]

Dipping sonar....................... <=200 120 628 m (135 m).......... 35 m (6 m).
Dipping sonar....................... >200 1 140 m (20 m)........... 0 m (1 m).
Dipping sonar....................... >200 30 260 m (49 m)........... 0 m (8 m).
Dipping sonar....................... >200 60 340 m (70 m)........... 23 m (10 m).
Dipping sonar....................... >200 120 500 m (112 m).......... 35 m (15 m).
MF1 ship sonar...................... <=200 1 1,069 m (252 m)........ 90 m (17 m).
MF1 ship sonar...................... <=200 30 1,069 m (252 m)........ 90 m (17 m).
MF1 ship sonar...................... <=200 60 1,528 m (465 m)........ 140 m (24 m).
MF1 ship sonar...................... <=200 120 1,792 m (636 m)........ 180 m (32 m).
MF1 ship sonar...................... >200 1 1,000 m (85 m)......... 85 m (3 m).
MF1 ship sonar...................... >200 30 1,000 m (85 m)......... 85 m (3 m).
MF1 ship sonar...................... >200 60 1,500 m (252 m)........ 130 m (7 m).
MF1 ship sonar...................... >200 120 1,944 m (484 m)........ 170 m (9 m).
MF1C ship sonar..................... <=200 1 1,069 m (252 m)........ 90 m (17 m).
MF1C ship sonar..................... <=200 30 1,792 m (636 m)........ 180 m (32 m).
MF1C ship sonar..................... <=200 60 2,319 m (1,021 m)...... 260 m (56 m).
MF1C ship sonar..................... <=200 120 2,845 m (1,479 m)...... 390 m (72 m).
MF1C ship sonar..................... >200 1 1,000 m (85 m)......... 85 m (3 m).
MF1C ship sonar..................... >200 30 1,944 m (484 m)........ 170 m (9 m).
MF1C ship sonar..................... >200 60 2,792 m (1,103 m)...... 250 m (21 m).
MF1C ship sonar..................... >200 120 4,000 m (1,599 m)...... 370 m (31 m).
MF1K ship sonar..................... <=200 1 193 m (37 m)........... 12 m (4 m).
MF1K ship sonar..................... <=200 30 355 m (73 m)........... 24 m (2 m).
MF1K ship sonar..................... <=200 60 470 m (83 m)........... 30 m (3 m).
MF1K ship sonar..................... <=200 120 668 m (126 m).......... 45 m (13 m).
MF1K ship sonar..................... >200 1 190 m (15 m)........... 5 m (5 m).
MF1K ship sonar..................... >200 30 340 m (34 m)........... 21 m (11 m).
MF1K ship sonar..................... >200 60 440 m (52 m)........... 25 m (3 m).
MF1K ship sonar..................... >200 120 625 m (66 m)........... 40 m (2 m).
Mine-hunting sonar.................. <=200 1 3 m (1 m).............. 0 m (0 m).
Mine-hunting sonar.................. <=200 30 6 m (1 m).............. 0 m (0 m).
Mine-hunting sonar.................. <=200 60 9 m (1 m).............. 0 m (0 m).
Mine-hunting sonar.................. <=200 120 13 m (2 m)............. 1 m (0 m).
Mine-hunting sonar.................. >200 1 0 m (0 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 30 5 m (2 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 60 8 m (3 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 120 12 m (0 m)............. 0 m (0 m).
Sonobuoy sonar...................... <=200 1 13 m (6 m)............. 0 m (0 m).
Sonobuoy sonar...................... <=200 30 25 m (6 m)............. 0 m (0 m).
Sonobuoy sonar...................... <=200 60 35 m (7 m)............. 0 m (1 m).
Sonobuoy sonar...................... <=200 120 50 m (4 m)............. 0 m (1 m).
Sonobuoy sonar...................... >200 1 0 m (6 m).............. 0 m (0 m).
Sonobuoy sonar...................... >200 30 23 m (10 m)............ 0 m (0 m).
Sonobuoy sonar...................... >200 60 35 m (11 m)............ 0 m (0 m).
Sonobuoy sonar...................... >200 120 50 m (3 m)............. 0 m (0 m).
----------------------------------------------------------------------------------------------------------------
Note: Median ranges are shown with standard deviation (SD) in parentheses. The Action Proponents split the LF
functional hearing group into LF and VLF based on Houser et al., (2024). NMFS updated acoustic technical
guidance (NMFS, 2024) does not include these data but we have included the VLF group here for reference.

Table 24--Low-Frequency Cetacean Ranges to Effects for Sonar
----------------------------------------------------------------------------------------------------------------
Duration
Sonar type Depth (m) (s) Range to TTS (SD) Range to AUD INJ (SD)
----------------------------------------------------------------------------------------------------------------
Dipping sonar....................... <=200 1 160 m (56 m)........... 12 m (4 m).
Dipping sonar....................... <=200 30 311 m (100 m).......... 21 m (6 m).
Dipping sonar....................... <=200 60 411 m (119 m).......... 25 m (7 m).
Dipping sonar....................... <=200 120 581 m (137 m).......... 35 m (11 m).
Dipping sonar....................... >200 1 150 m (82 m)........... 0 m (6 m).
Dipping sonar....................... >200 30 240 m (123 m).......... 17 m (10 m).
Dipping sonar....................... >200 60 287 m (160 m).......... 25 m (13 m).
Dipping sonar....................... >200 120 409 m (133 m).......... 35 m (18 m).
MF1 ship sonar...................... <=200 1 1,069 m (280 m)........ 95 m (19 m).
MF1 ship sonar...................... <=200 30 1,069 m (280 m)........ 95 m (19 m).
MF1 ship sonar...................... <=200 60 1,500 m (500 m)........ 140 m (24 m).
MF1 ship sonar...................... <=200 120 1,736 m (668 m)........ 180 m (30 m).
MF1 ship sonar...................... >200 1 1,000 m (185 m)........ 90 m (5 m).
MF1 ship sonar...................... >200 30 1,000 m (185 m)........ 90 m (5 m).
MF1 ship sonar...................... >200 60 1,569 m (415 m)........ 140 m (12 m).
MF1 ship sonar...................... >200 120 2,153 m (734 m)........ 180 m (14 m).

[[Page 32216]]

MF1C ship sonar..................... <=200 1 1,069 m (280 m)........ 95 m (19 m).
MF1C ship sonar..................... <=200 30 1,736 m (668 m)........ 180 m (30 m).
MF1C ship sonar..................... <=200 60 2,194 m (1,062 m)...... 270 m (49 m).
MF1C ship sonar..................... <=200 120 2,667 m (1,519 m)...... 399 m (68 m).
MF1C ship sonar..................... >200 1 1,000 m (185 m)........ 90 m (5 m).
MF1C ship sonar..................... >200 30 2,153 m (734 m)........ 180 m (14 m).
MF1C ship sonar..................... >200 60 3,111 m (1,305 m)...... 260 m (21 m).
MF1C ship sonar..................... >200 120 4,333 m (1,845 m)...... 380 m (29 m).
MF1K ship sonar..................... <=200 1 200 m (34 m)........... 14 m (1 m).
MF1K ship sonar..................... <=200 30 360 m (67 m)........... 25 m (1 m).
MF1K ship sonar..................... <=200 60 480 m (84 m)........... 30 m (4 m).
MF1K ship sonar..................... <=200 120 661 m (135 m).......... 45 m (14 m).
MF1K ship sonar..................... >200 1 200 m (21 m)........... 12 m (1 m).
MF1K ship sonar..................... >200 30 350 m (32 m)........... 24 m (0 m).
MF1K ship sonar..................... >200 60 450 m (44 m)........... 30 m (0 m).
MF1K ship sonar..................... >200 120 650 m (88 m)........... 45 m (0 m).
Mine-hunting sonar.................. <=200 1 8 m (5 m).............. 0 m (0 m).
Mine-hunting sonar.................. <=200 30 15 m (8 m)............. 1 m (0 m).
Mine-hunting sonar.................. <=200 60 21 m (12 m)............ 2 m (1 m).
Mine-hunting sonar.................. <=200 120 30 m (12 m)............ 3 m (2 m).
Mine-hunting sonar.................. >200 1 8 m (5 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 30 15 m (8 m)............. 0 m (0 m).
Mine-hunting sonar.................. >200 60 21 m (12 m)............ 0 m (1 m).
Mine-hunting sonar.................. >200 120 30 m (12 m)............ 0 m (1 m).
Sonobuoy sonar...................... <=200 1 0 m (8 m).............. 0 m (0 m).
Sonobuoy sonar...................... <=200 30 25 m (12 m)............ 0 m (0 m).
Sonobuoy sonar...................... <=200 60 35 m (18 m)............ 0 m (0 m).
Sonobuoy sonar...................... <=200 120 55 m (25 m)............ 0 m (1 m).
Sonobuoy sonar...................... >200 1 0 m (7 m).............. 0 m (0 m).
Sonobuoy sonar...................... >200 30 19 m (12 m)............ 0 m (0 m).
Sonobuoy sonar...................... >200 60 35 m (19 m)............ 0 m (0 m).
Sonobuoy sonar...................... >200 120 55 m (28 m)............ 0 m (1 m).
----------------------------------------------------------------------------------------------------------------
Note: Median ranges are shown with standard deviation (SD) in parentheses. The Action Proponents split the LF
functional hearing group into LF and VLF based on Houser et al., (2024). NMFS updated acoustic technical
guidance (NMFS, 2024) does not include these data but we have included the VLF group here for reference.

Table 25--High-Frequency Cetacean Ranges to Effects for Sonar
----------------------------------------------------------------------------------------------------------------
Duration
Sonar type Depth (m) (s) Range to TTS (SD) Range to AUD INJ (SD)
----------------------------------------------------------------------------------------------------------------
Dipping sonar....................... <=200 1 55 m (15 m)............ 5 m (2 m).
Dipping sonar....................... <=200 30 120 m (34 m)........... 9 m (4 m).
Dipping sonar....................... <=200 60 170 m (50 m)........... 12 m (5 m).
Dipping sonar....................... <=200 120 250 m (85 m)........... 18 m (6 m).
Dipping sonar....................... >200 1 50 m (28 m)............ 0 m (2 m).
Dipping sonar....................... >200 30 100 m (54 m)........... 0 m (4 m).
Dipping sonar....................... >200 60 130 m (74 m)........... 0 m (5 m).
Dipping sonar....................... >200 120 200 m (105 m).......... 0 m (8 m).
MF1 ship sonar...................... <=200 1 644 m (113 m).......... 45 m (7 m).
MF1 ship sonar...................... <=200 30 644 m (113 m).......... 45 m (7 m).
MF1 ship sonar...................... <=200 60 910 m (177 m).......... 65 m (12 m).
MF1 ship sonar...................... <=200 120 1,011 m (243 m)........ 85 m (14 m).
MF1 ship sonar...................... >200 1 600 m (52 m)........... 40 m (11 m).
MF1 ship sonar...................... >200 30 600 m (52 m)........... 40 m (11 m).
MF1 ship sonar...................... >200 60 875 m (93 m)........... 65 m (14 m).
MF1 ship sonar...................... >200 120 1,000 m (126 m)........ 85 m (7 m).
MF1C ship sonar..................... <=200 1 644 m (113 m).......... 45 m (7 m).
MF1C ship sonar..................... <=200 30 1,011 m (243 m)........ 85 m (14 m).
MF1C ship sonar..................... <=200 60 1,458 m (437 m)........ 130 m (23 m).
MF1C ship sonar..................... <=200 120 1,903 m (730 m)........ 200 m (36 m).
MF1C ship sonar..................... >200 1 600 m (52 m)........... 40 m (11 m).
MF1C ship sonar..................... >200 30 1,000 m (126 m)........ 85 m (7 m).
MF1C ship sonar..................... >200 60 1,500 m (309 m)........ 130 m (12 m).
MF1C ship sonar..................... >200 120 2,142 m (786 m)........ 200 m (17 m).
MF1K ship sonar..................... <=200 1 100 m (21 m)........... 7 m (3 m).
MF1K ship sonar..................... <=200 30 190 m (34 m)........... 13 m (4 m).
MF1K ship sonar..................... <=200 60 250 m (51 m)........... 17 m (5 m).
MF1K ship sonar..................... <=200 120 363 m (72 m)........... 25 m (2 m).
MF1K ship sonar..................... >200 1 100 m (19 m)........... 0 m (3 m).

[[Page 32217]]

MF1K ship sonar..................... >200 30 180 m (20 m)........... 11 m (6 m).
MF1K ship sonar..................... >200 60 240 m (27 m)........... 16 m (8 m).
MF1K ship sonar..................... >200 120 350 m (39 m)........... 24 m (11 m).
Mine-hunting sonar.................. <=200 1 8 m (3 m).............. 0 m (0 m).
Mine-hunting sonar.................. <=200 30 15 m (5 m)............. 1 m (0 m).
Mine-hunting sonar.................. <=200 60 21 m (6 m)............. 1 m (1 m).
Mine-hunting sonar.................. <=200 120 30 m (6 m)............. 2 m (1 m).
Mine-hunting sonar.................. >200 1 7 m (3 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 30 15 m (6 m)............. 0 m (0 m).
Mine-hunting sonar.................. >200 60 21 m (7 m)............. 0 m (1 m).
Mine-hunting sonar.................. >200 120 30 m (5 m)............. 0 m (1 m).
Sonobuoy sonar...................... <=200 1 8 m (4 m).............. 0 m (0 m).
Sonobuoy sonar...................... <=200 30 18 m (8 m)............. 0 m (0 m).
Sonobuoy sonar...................... <=200 60 25 m (12 m)............ 0 m (0 m).
Sonobuoy sonar...................... <=200 120 35 m (14 m)............ 0 m (1 m).
Sonobuoy sonar...................... >200 1 0 m (4 m).............. 0 m (0 m).
Sonobuoy sonar...................... >200 30 0 m (9 m).............. 0 m (0 m).
Sonobuoy sonar...................... >200 60 0 m (12 m)............. 0 m (0 m).
Sonobuoy sonar...................... >200 120 30 m (16 m)............ 0 m (1 m).
----------------------------------------------------------------------------------------------------------------
Note: Median ranges are shown with standard deviation (SD) in parentheses.

Table 26--Very High-Frequency Cetacean Ranges to Effects for Sonar
----------------------------------------------------------------------------------------------------------------
Duration
Sonar type Depth (m) (s) Range to TTS (SD) Range to AUD INJ (SD)
----------------------------------------------------------------------------------------------------------------
Dipping sonar....................... <=200 1 100 m (30 m)........... 8 m (2 m).
Dipping sonar....................... <=200 30 202 m (77 m)........... 14 m (4 m).
Dipping sonar....................... <=200 60 278 m (93 m)........... 19 m (5 m).
Dipping sonar....................... <=200 120 420 m (100 m).......... 25 m (7 m).
Dipping sonar....................... >200 1 95 m (50 m)............ 0 m (3 m).
Dipping sonar....................... >200 30 180 m (101 m).......... 0 m (6 m).
Dipping sonar....................... >200 60 240 m (123 m).......... 14 m (8 m).
Dipping sonar....................... >200 120 330 m (85 m)........... 24 m (12 m).
MF1 ship sonar...................... <=200 1 1,528 m (471 m)........ 150 m (25 m).
MF1 ship sonar...................... <=200 30 1,528 m (471 m)........ 150 m (25 m).
MF1 ship sonar...................... <=200 60 2,000 m (756 m)........ 220 m (39 m).
MF1 ship sonar...................... <=200 120 2,250 m (974 m)........ 280 m (57 m).
MF1 ship sonar...................... >200 1 1,569 m (357 m)........ 150 m (12 m).
MF1 ship sonar...................... >200 30 1,569 m (357 m)........ 150 m (12 m).
MF1 ship sonar...................... >200 60 2,403 m (885 m)........ 220 m (20 m).
MF1 ship sonar...................... >200 120 2,944 m (1,143 m)...... 270 m (27 m).
MF1C ship sonar..................... <=200 1 1,528 m (471 m)........ 150 m (25 m).
MF1C ship sonar..................... <=200 30 2,250 m (974 m)........ 280 m (57 m).
MF1C ship sonar..................... <=200 60 2,722 m (1,373 m)...... 417 m (68 m).
MF1C ship sonar..................... <=200 120 3,330 m (1,819 m)...... 588 m (99 m).
MF1C ship sonar..................... >200 1 1,569 m (357 m)........ 150 m (12 m).
MF1C ship sonar..................... >200 30 2,944 m (1,143 m)...... 270 m (27 m).
MF1C ship sonar..................... >200 60 4,097 m (1,620 m)...... 390 m (29 m).
MF1C ship sonar..................... >200 120 5,972 m (2,314 m)...... 550 m (38 m).
MF1K ship sonar..................... <=200 1 315 m (60 m)........... 20 m (2 m).
MF1K ship sonar..................... <=200 30 550 m (103 m).......... 35 m (5 m).
MF1K ship sonar..................... <=200 60 712 m (139 m).......... 50 m (12 m).
MF1K ship sonar..................... <=200 120 958 m (214 m).......... 85 m (12 m).
MF1K ship sonar..................... >200 1 300 m (37 m)........... 16 m (2 m).
MF1K ship sonar..................... >200 30 525 m (43 m)........... 35 m (1 m).
MF1K ship sonar..................... >200 60 675 m (66 m)........... 50 m (2 m).
MF1K ship sonar..................... >200 120 975 m (116 m).......... 85 m (4 m).
Mine-hunting sonar.................. <=200 1 90 m (26 m)............ 9 m (1 m).
Mine-hunting sonar.................. <=200 30 190 m (85 m)........... 16 m (2 m).
Mine-hunting sonar.................. <=200 60 329 m (128 m).......... 22 m (2 m).
Mine-hunting sonar.................. <=200 120 521 m (166 m).......... 30 m (3 m).
Mine-hunting sonar.................. >200 1 90 m (6 m)............. 7 m (1 m).
Mine-hunting sonar.................. >200 30 150 m (30 m)........... 15 m (0 m).
Mine-hunting sonar.................. >200 60 210 m (57 m)........... 22 m (0 m).
Mine-hunting sonar.................. >200 120 300 m (79 m)........... 30 m (0 m).
Sonobuoy sonar...................... <=200 1 65 m (20 m)............ 0 m (2 m).
Sonobuoy sonar...................... <=200 30 126 m (39 m)........... 9 m (5 m).
Sonobuoy sonar...................... <=200 60 191 m (79 m)........... 15 m (5 m).
Sonobuoy sonar...................... <=200 120 314 m (120 m).......... 22 m (7 m).

[[Page 32218]]

Sonobuoy sonar...................... >200 1 65 m (31 m)............ 0 m (1 m).
Sonobuoy sonar...................... >200 30 110 m (59 m)........... 0 m (4 m).
Sonobuoy sonar...................... >200 60 180 m (75 m)........... 10 m (7 m).
Sonobuoy sonar...................... >200 120 276 m (72 m)........... 21 m (10 m).
----------------------------------------------------------------------------------------------------------------
Note: Median ranges are shown with standard deviation (SD) in parentheses.

Table 27--Phocid Carnivore in Water Ranges to Effects for Sonar
----------------------------------------------------------------------------------------------------------------
Duration
Sonar type Depth (m) (s) Range to TTS (SD) Range to AUD INJ (SD)
----------------------------------------------------------------------------------------------------------------
Dipping sonar....................... <=200 1 200 m (52 m)........... 0 m (7 m).
Dipping sonar....................... <=200 30 370 m (101 m).......... 21 m (12 m).
Dipping sonar....................... <=200 60 496 m (134 m).......... 30 m (15 m).
Dipping sonar....................... <=200 120 707 m (144 m).......... 45 m (12 m).
Dipping sonar....................... >200 1 160 m (71 m)........... 0 m (4 m).
Dipping sonar....................... >200 30 298 m (129 m).......... 0 m (8 m).
Dipping sonar....................... >200 60 370 m (170 m).......... 0 m (10 m).
Dipping sonar....................... >200 120 550 m (80 m)........... 0 m (19 m).
MF1 ship sonar...................... <=200 1 1,250 m (384 m)........ 120 m (20 m).
MF1 ship sonar...................... <=200 30 1,250 m (384 m)........ 120 m (20 m).
MF1 ship sonar...................... <=200 60 1,625 m (632 m)........ 180 m (33 m).
MF1 ship sonar...................... <=200 120 1,875 m (833 m)........ 230 m (45 m).
MF1 ship sonar...................... >200 1 1,250 m (282 m)........ 120 m (53 m).
MF1 ship sonar...................... >200 30 1,250 m (282 m)........ 120 m (53 m).
MF1 ship sonar...................... >200 60 1,792 m (696 m)........ 180 m (21 m).
MF1 ship sonar...................... >200 120 2,264 m (982 m)........ 230 m (23 m).
MF1C ship sonar..................... <=200 1 1,250 m (384 m)........ 120 m (20 m).
MF1C ship sonar..................... <=200 30 1,875 m (833 m)........ 230 m (45 m).
MF1C ship sonar..................... <=200 60 2,333 m (1,223 m)...... 330 m (73 m).
MF1C ship sonar..................... <=200 120 2,833 m (1,633 m)...... 481 m (97 m).
MF1C ship sonar..................... >200 1 1,250 m (282 m)........ 120 m (53 m).
MF1C ship sonar..................... >200 30 2,264 m (982 m)........ 230 m (23 m).
MF1C ship sonar..................... >200 60 3,368 m (1,399 m)...... 330 m (31 m).
MF1C ship sonar..................... >200 120 4,500 m (1,973 m)...... 462 m (46 m).
MF1K ship sonar..................... <=200 1 248 m (58 m)........... 0 m (9 m).
MF1K ship sonar..................... <=200 30 435 m (97 m)........... 25 m (8 m).
MF1K ship sonar..................... <=200 60 550 m (133 m).......... 35 m (10 m).
MF1K ship sonar..................... <=200 120 771 m (190 m).......... 65 m (14 m).
MF1K ship sonar..................... >200 1 240 m (26 m)........... 0 m (8 m).
MF1K ship sonar..................... >200 30 430 m (48 m)........... 24 m (13 m).
MF1K ship sonar..................... >200 60 550 m (61 m)........... 35 m (16 m).
MF1K ship sonar..................... >200 120 775 m (105 m).......... 65 m (28 m).
Mine-hunting sonar.................. <=200 1 12 m (7 m)............. 0 m (0 m).
Mine-hunting sonar.................. <=200 30 24 m (11 m)............ 0 m (1 m).
Mine-hunting sonar.................. <=200 60 35 m (11 m)............ 0 m (1 m).
Mine-hunting sonar.................. <=200 120 50 m (15 m)............ 0 m (2 m).
Mine-hunting sonar.................. >200 1 0 m (5 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 30 22 m (9 m)............. 0 m (0 m).
Mine-hunting sonar.................. >200 60 30 m (4 m)............. 0 m (1 m).
Mine-hunting sonar.................. >200 120 45 m (5 m)............. 0 m (1 m).
Sonobuoy sonar...................... <=200 1 0 m (11 m)............. 0 m (0 m).
Sonobuoy sonar...................... <=200 30 35 m (16 m)............ 0 m (1 m).
Sonobuoy sonar...................... <=200 60 50 m (19 m)............ 0 m (1 m).
Sonobuoy sonar...................... <=200 120 75 m (20 m)............ 0 m (3 m).
Sonobuoy sonar...................... >200 1 0 m (7 m).............. 0 m (0 m).
Sonobuoy sonar...................... >200 30 0 m (16 m)............. 0 m (0 m).
Sonobuoy sonar...................... >200 60 45 m (23 m)............ 0 m (0 m).
Sonobuoy sonar...................... >200 120 70 m (32 m)............ 0 m (1 m).
----------------------------------------------------------------------------------------------------------------
Note: Median ranges are shown with standard deviation (SD) in parentheses.

Table 28--Otariid Carnivore in Water Ranges to Effects for Sonar
----------------------------------------------------------------------------------------------------------------
Duration
Sonar type Depth (m) (s) Range to TTS (SD) Range to AUD INJ (SD)
----------------------------------------------------------------------------------------------------------------
Dipping sonar....................... <=200 1 60 m (16 m)............ 0 m (3 m).
Dipping sonar....................... <=200 30 130 m (40 m)........... 0 m (5 m).
Dipping sonar....................... <=200 60 180 m (58 m)........... 0 m (6 m).

[[Page 32219]]

Dipping sonar....................... <=200 120 274 m (88 m)........... 11 m (9 m).
Dipping sonar....................... >200 1 55 m (30 m)............ 0 m (2 m).
Dipping sonar....................... >200 30 120 m (66 m)........... 0 m (4 m).
Dipping sonar....................... >200 60 160 m (90 m)........... 0 m (5 m).
Dipping sonar....................... >200 120 210 m (116 m).......... 0 m (8 m).
MF1 ship sonar...................... <=200 1 726 m (148 m).......... 50 m (10 m).
MF1 ship sonar...................... <=200 30 726 m (148 m).......... 50 m (10 m).
MF1 ship sonar...................... <=200 60 981 m (220 m).......... 80 m (12 m).
MF1 ship sonar...................... <=200 120 1,139 m (296 m)........ 109 m (18 m).
MF1 ship sonar...................... >200 1 725 m (93 m)........... 50 m (1 m).
MF1 ship sonar...................... >200 30 725 m (93 m)........... 50 m (1 m).
MF1 ship sonar...................... >200 60 1,000 m (157 m)........ 80 m (5 m).
MF1 ship sonar...................... >200 120 1,250 m (251 m)........ 100 m (8 m).
MF1C ship sonar..................... <=200 1 726 m (148 m).......... 50 m (10 m).
MF1C ship sonar..................... <=200 30 1,139 m (296 m)........ 109 m (18 m).
MF1C ship sonar..................... <=200 60 1,500 m (462 m)........ 160 m (23 m).
MF1C ship sonar..................... <=200 120 1,861 m (690 m)........ 240 m (40 m).
MF1C ship sonar..................... >200 1 725 m (93 m)........... 50 m (1 m).
MF1C ship sonar..................... >200 30 1,250 m (251 m)........ 100 m (8 m).
MF1C ship sonar..................... >200 60 1,750 m (549 m)........ 160 m (12 m).
MF1C ship sonar..................... >200 120 2,250 m (1,071 m)...... 240 m (22 m).
MF1K ship sonar..................... <=200 1 120 m (22 m)........... 8 m (4 m).
MF1K ship sonar..................... <=200 30 230 m (40 m)........... 16 m (4 m).
MF1K ship sonar..................... <=200 60 300 m (56 m)........... 20 m (3 m).
MF1K ship sonar..................... <=200 120 426 m (77 m)........... 25 m (4 m).
MF1K ship sonar..................... >200 1 120 m (12 m)........... 0 m (4 m).
MF1K ship sonar..................... >200 30 220 m (30 m)........... 14 m (6 m).
MF1K ship sonar..................... >200 60 290 m (38 m)........... 20 m (5 m).
MF1K ship sonar..................... >200 120 420 m (58 m)........... 25 m (1 m).
Mine-hunting sonar.................. <=200 1 6 m (3 m).............. 0 m (0 m).
Mine-hunting sonar.................. <=200 30 11 m (6 m)............. 0 m (0 m).
Mine-hunting sonar.................. <=200 60 18 m (8 m)............. 0 m (0 m).
Mine-hunting sonar.................. <=200 120 25 m (10 m)............ 0 m (1 m).
Mine-hunting sonar.................. >200 1 6 m (3 m).............. 0 m (0 m).
Mine-hunting sonar.................. >200 30 11 m (5 m)............. 0 m (0 m).
Mine-hunting sonar.................. >200 60 18 m (7 m)............. 0 m (0 m).
Mine-hunting sonar.................. >200 120 25 m (10 m)............ 0 m (1 m).
Sonobuoy sonar...................... <=200 1 0 m (6 m).............. 0 m (0 m).
Sonobuoy sonar...................... <=200 30 18 m (11 m)............ 0 m (0 m).
Sonobuoy sonar...................... <=200 60 30 m (13 m)............ 0 m (1 m).
Sonobuoy sonar...................... <=200 120 45 m (20 m)............ 0 m (1 m).
Sonobuoy sonar...................... >200 1 0 m (5 m).............. 0 m (0 m).
Sonobuoy sonar...................... >200 30 0 m (11 m)............. 0 m (0 m).
Sonobuoy sonar...................... >200 60 25 m (14 m)............ 0 m (0 m).
Sonobuoy sonar...................... >200 120 40 m (22 m)............ 0 m (1 m).
----------------------------------------------------------------------------------------------------------------
Note: Median ranges are shown with standard deviation (SD) in parentheses.

Air Guns
Ranges to effects for air guns were determined by modeling the
distance that sound would need to propagate to reach exposure level
thresholds specific to a hearing group that would cause behavioral
response, TTS, and AUD INJ, as described in the Criteria and Thresholds
Technical Report. The air gun ranges to effects for TTS and AUD INJ in
table 29 are based on the metric (i.e., SEL or SPL) that produced
larger ranges.

Table 29--Range to Effects for Air Guns
----------------------------------------------------------------------------------------------------------------
Behavioral Range to TTS Range to AUD INJ
Functional hearing group Depth (m) Cluster size disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
VLF........................ <=200 1 N/A............... 5 m (0 m)........ 1 m (1 m).
VLF........................ <=200 10 114 m (6 m)....... 81 m (1 m)....... 14 m (0 m).
VLF........................ >200 1 N/A............... 5 m (0 m)........ 1 m (1 m).
VLF........................ >200 10 115 m (7 m)....... 81 m (1 m)....... 14 m (0 m).
LF......................... <=200 1 N/A............... 5 m (0 m)........ 2 m (0 m).
LF......................... <=200 10 104 m (10 m)...... 36 m (1 m)....... 6 m (0 m).
LF......................... >200 1 N/A............... 5 m (0 m)........ 2 m (0 m).
LF......................... >200 10 107 m (11 m)...... 35 m (1 m)....... 6 m (0 m).
HF......................... <=200 1 N/A............... 2 m (1 m)........ 0 m (0 m).
HF......................... <=200 10 111 m (10 m)...... 2 m (1 m)........ 0 m (0 m).

[[Page 32220]]

HF......................... >200 1 N/A............... 2 m (1 m)........ 0 m (0 m).
HF......................... >200 10 112 m (13 m)...... 2 m (1 m)........ 0 m (0 m).
VHF........................ <=200 1 N/A............... 51 m (2 m)....... 25 m (0 m).
VHF........................ <=200 10 111 m (13 m)...... 51 m (2 m)....... 25 m (0 m).
VHF........................ >200 1 N/A............... 50 m (1 m)....... 25 m (0 m).
VHF........................ >200 10 119 m (14 m)...... 50 m (1 m)....... 25 m (0 m).
PCW........................ <=200 1 N/A............... 5 m (2 m)........ 2 m (1 m).
PCW........................ <=200 10 110 m (11 m)...... 7 m (3 m)........ 2 m (1 m).
PCW........................ >200 1 N/A............... 5 m (2 m)........ 2 m (1 m).
PCW........................ >200 10 113 m (23 m)...... 7 m (3 m)........ 2 m (1 m).
OCW........................ <=200 1 N/A............... 2 m (0 m)........ 1 m (0 m).
OCW........................ <=200 10 112 m (18 m)...... 2 m (0 m)........ 1 m (0 m).
OCW........................ >200 1 N/A............... 2 m (0 m)........ 1 m (0 m).
OCW........................ >200 10 118 m (19 m)...... 2 m (0 m)........ 1 m (0 m).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. The values listed for TTS and AUD INJ are the greater of the respective SPL and SEL
ranges. Median ranges are shown with standard deviation (SD) in parentheses. The Action Proponents split the
LF functional hearing group into LF and VLF based on Houser et al., (2024). NMFS updated acoustic technical
guidance (NMFS, 2024) does not include these data but we have included the VLF group here for reference.

Pile Driving
Only California sea lions (U.S. stock) and harbor seals (California
stock) are expected to be present in the waters of Port Hueneme, where
impact and vibratory pile driving and extraction is proposed to occur
up to 12 times per year. Table 30 shows the predicted ranges to AUD
INJ, TTS, and behavioral response for the otariid carnivore in water
and phocid carnivore in water hearing groups (the only functional
hearing groups expected in the vicinity of pile driving and extraction
activities) that were analyzed for their exposure to impact and
vibratory pile driving. These ranges were estimated based on activity
parameters described in the Acoustic Stressors section of the Explosive
and Acoustic Analysis Report (see appendix A of the application) and
using the calculations described in the Acoustic Impacts Technical
Report.

Table 30--Range to Effects for Pinnipeds from Pile Driving
----------------------------------------------------------------------------------------------------------------
Behavioral Range to
Pile type Method Functional hearing response Range to AUD INJ
group (m) TTS (m) (m)
----------------------------------------------------------------------------------------------------------------
20-inch (51 cm) round timber/ Impact............. OCW............... 46 43 4
plastic.
20-inch (51 cm) H steel......... Impact............. OCW............... 215 201 20
20-inch (51 cm) round or H steel/ Impact............. OCW............... 858 685 69
timber/plastic.
27.5-inch (70 cm) sheet or Z Vibratory.......... OCW............... 3,981 12 1
steel.
20-inch (51 cm) round steel/ Vibratory.......... OCW............... 3,981 36 2
timber/plastic.
20-inch (51 cm) round timber/ Impact............. PCW............... 46 116 12
plastic.
20-inch (51 cm) H steel......... Impact............. PCW............... 215 538 54
20-inch (51 cm) round or H steel/ Impact............. PCW............... 858 1,839 184
timber/plastic.
27.5-inch (70 cm) sheet or Z Vibratory.......... PCW............... 11,659 35 2
steel.
20-inch (51 cm) round steel/ Vibratory.......... PCW............... 11,659 105 5
timber/plastic.
----------------------------------------------------------------------------------------------------------------
Note: cm = centimeter.

Explosives
This section provides the range (i.e., distance) over which
specific physiological or behavioral effects are expected to occur
based on the explosive criteria (see section 6.2.1 (Impacts from
Explosives) of the application and the Criteria and Thresholds
Technical Report and the explosive propagation calculations from NAEMO.
The range to effects are shown for a range of explosive bins, from E1
(0.1-0.25 lb (0.045-0.113 kg) NEW) to E16 (greater than 7,250-14,500 lb
(3,288-6,577 kg) NEW (ship shock trial only)) (table 31 through table
36). Ranges are determined by modeling the distance that noise from an
explosion would need to propagate to reach exposure level thresholds
specific to a hearing group that would cause behavioral response (to
the degree of Level B behavioral harassment), TTS, and AUD INJ. NMFS
has reviewed the range distance to effect data provided by the Action
Proponents and concurs with the analysis. Range to effects is important
information in not only predicting impacts from explosives, but also in
verifying the accuracy of model results against real-world situations
and determining appropriate mitigation ranges to avoid higher level
effects, especially injury to marine mammals. For additional
information on how ranges to impacts from explosions were estimated,
see the Acoustic Impacts Technical Report.
Table 31 through table 36 show the minimum, average, and maximum
ranges to onset of auditory and likely behavioral effects that qualify
as Level B harassment for all functional hearing groups based on the
developed thresholds. Ranges are provided for a representative source
depth and cluster size (i.e., the number of rounds fired, or buoys
dropped, within a very short duration) for each bin. Ranges for
behavioral response are only provided if more than one explosive
cluster occurs. As noted previously, single explosions at received
sound levels below TTS and AUD INJ thresholds are most likely to result
in a brief alerting or orienting

[[Page 32221]]

response. For events with multiple explosions, sound from successive
explosions can be expected to accumulate and increase the range to the
onset of an impact based on SEL thresholds. Modeled ranges to TTS and
AUD INJ based on peak pressure for a single explosion generally exceed
the modeled ranges based on SEL even when accumulated for multiple
explosions. Peak pressure-based ranges are estimated using the best
available science; however, data on peak pressure at far distances from
explosions are very limited. The explosive ranges to effects for TTS
and AUD INJ that are in the tables are based on the metric (i.e., SEL
or SPL) that produced larger ranges.
Table 37 shows ranges to non-auditory injury and mortality as a
function of animal mass and explosive bin. For non-auditory injury, the
larger of the ranges to slight lung injury or gastrointestinal tract
injury was used as a conservative estimate, and the boxplots in
appendix A to the application present ranges for both metrics for
comparison. For the non-auditory metric, ranges are only available for
a cluster size of one. Animals within water volumes encompassing the
estimated range to non-auditory injury would be expected to receive
minor injuries at the outer ranges, increasing to more substantial
injuries, and finally mortality as an animal approaches the detonation
point.

Table 31--Very Low-Frequency Cetacean Ranges to Effects for Explosives
----------------------------------------------------------------------------------------------------------------
Range to
Bin Depth (m) Cluster size behavioral Range to TTS (SD) Range to AUD INJ
disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
E1......................... <=200 1 N/A............... 206 m (73 m)..... 95 m (2 m).
E1......................... <=200 5 618 m (230 m)..... 390 m (161 m).... 95 m (19 m).
E1......................... <=200 25 1,246 m (444 m)... 785 m (267 m).... 182 m (61 m).
E1......................... <=200 50 1,419 m (471 m)... 800 m (178 m).... 250 m (34 m).
E1......................... >200 1 N/A............... 220 m (55 m)..... 95 m (3 m).
E1......................... >200 5 600 m (61 m)...... 430 m (18 m)..... 95 m (2 m).
E1......................... >200 25 950 m (155 m)..... 700 m (84 m)..... 190 m (5 m).
E1......................... >200 50 1,000 m (290 m)... 850 m (98 m)..... 270 m (5 m).
E2......................... <=200 1 N/A............... 362 m (42 m)..... 130 m (12 m).
E2......................... >200 1 N/A............... 370 m (46 m)..... 130 m (13 m).
E3......................... <=200 1 N/A............... 489 m (387 m).... 213 m (6 m).
E3......................... <=200 5 1,531 m (615 m)... 909 m (370 m).... 213 m (6 m).
E3......................... <=200 25 2,764 m (1,211 m). 1,722 m (685 m).. 414 m (178 m).
E3......................... >200 1 N/A............... 825 m (304 m).... 214 m (7 m).
E3......................... >200 5 1,000 m (346 m)... 751 m (154 m).... 220 m (5 m).
E3......................... >200 25 1,750 m (971 m)... 1,000 m (369 m).. 420 m (26 m).
E4......................... <=200 1 N/A............... 1,875 m (768 m).. 382 m (26 m).
E4......................... >200 1 N/A............... 1,250 m (277 m).. 377 m (28 m).
E5......................... <=200 1 N/A............... 815 m (851 m).... 358 m (27 m).
E5......................... <=200 5 2,986 m (1,306 m). 1,586 m (714 m).. 358 m (27 m).
E5......................... >200 1 N/A............... 650 m (152 m).... 343 m (25 m).
E5......................... >200 5 2,146 m (956 m)... 1,056 m (452 m).. 350 m (54 m).
E5......................... >200 20 3,889 m (975 m)... 2,625 m (600 m).. 575 m (178 m).
E6......................... <=200 1 N/A............... 1,836 m (1,341 m) 534 m (382 m).
E6......................... <=200 15 7,258 m (1,106 m). 5,397 m (814 m).. 2,029 m (104 m).
E6......................... >200 1 N/A............... 1,347 m (762 m).. 516 m (48 m).
E7......................... <=200 1 N/A............... 1,651 m (729 m).. 535 m (25 m).
E7......................... >200 1 N/A............... 1,556 m (1,347 m) 537 m (24 m).
E8......................... <=200 1 N/A............... 2,549 m (485 m).. 769 m (55 m).
E8......................... >200 1 N/A............... 2,519 m (477 m).. 754 m (54 m).
E9......................... <=200 1 N/A............... 3,417 m (1,563 m) 755 m (49 m).
E9......................... >200 1 N/A............... 2,667 m (1,186 m) 754 m (49 m).
E10........................ <=200 1 N/A............... 4,272 m (840 m).. 891 m (88 m).
E10........................ >200 1 N/A............... 4,264 m (820 m).. 889 m (100 m).
E11........................ <=200 1 N/A............... 14,182 m (3,939 1,778 m (60 m).
m).
E11........................ >200 1 N/A............... 14,814 m (4,258 1,833 m (116 m).
m).
E12........................ <=200 1 N/A............... 4,523 m (910 m).. 992 m (78 m).
E12........................ >200 1 N/A............... 4,349 m (813 m).. 981 m (165 m).
E13........................ <=200 1 N/A............... 7,208 m (5,750 m) 3,361 m (1,875
m).
E16........................ >200 1 N/A............... 10,778 m (8,250 2,438 m (65 m).
m).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Behavioral response criteria are applied to explosive clusters >1. The values listed
for TTS and AUD INJ are the greater of the respective SPL and SEL ranges. Median ranges are shown with
standard deviation (SD) in parentheses. The Action Proponents split the LF functional hearing group into LF
and VLF based on Houser et al. (2024). NMFS updated acoustic technical guidance (NMFS, 2024) does not include
these data but we have included the VLF group here for reference. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2
(>0.25-0.5 lbs (0.113-0.23 kg)), E3 (>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10
lbs (2.27-4.54 kg)), E6 (>10-20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-27.2 kg)), E8 (>60-100 lbs (27.2-
45.4 kg)), E9 (>100-250 lbs (45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)),
E12 (>675-1,000 lbs (306-454 kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

Table 32--Low-Frequency Cetacean Ranges to Effects for Explosives
----------------------------------------------------------------------------------------------------------------
Range to
Bin Depth (m) Cluster size behavioral Range to TTS (SD) Range to AUD INJ
disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
E1......................... <=200 1 N/A............... 214 m (76 m)..... 92 m (7 m).

[[Page 32222]]

E1......................... <=200 5 726 m (232 m)..... 428 m (164 m).... 100 m (22 m).
E1......................... <=200 25 1,342 m (462 m)... 884 m (266 m).... 194 m (63 m).
E1......................... <=200 50 1,457 m (602 m)... 846 m (296 m).... 240 m (47 m).
E1......................... >200 1 N/A............... 250 m (60 m)..... 93 m (7 m).
E1......................... >200 5 725 m (140 m)..... 480 m (87 m)..... 110 m (8 m).
E1......................... >200 25 1,000 m (243 m)... 800 m (162 m).... 220 m (24 m).
E1......................... >200 50 1,153 m (318 m)... 950 m (179 m).... 310 m (39 m).
E2......................... <=200 1 N/A............... 375 m (57 m)..... 128 m (16 m).
E2......................... >200 1 N/A............... 381 m (59 m)..... 129 m (17 m).
E3......................... <=200 1 N/A............... 542 m (257 m).... 198 m (13 m).
E3......................... <=200 5 1,482 m (563 m)... 946 m (328 m).... 205 m (86 m).
E3......................... <=200 25 2,346 m (1,019 m). 1,664 m (605 m).. 435 m (159 m).
E3......................... >200 1 N/A............... 775 m (206 m).... 199 m (14 m).
E3......................... >200 5 1,000 m (364 m)... 861 m (191 m).... 240 m (33 m).
E3......................... >200 25 1,500 m (916 m)... 1,000 m (405 m).. 361 m (110 m).
E4......................... <=200 1 N/A............... 1,586 m (653 m).. 372 m (42 m).
E4......................... >200 1 N/A............... 1,000 m (257 m).. 365 m (44 m).
E5......................... <=200 1 N/A............... 854 m (753 m).... 305 m (39 m).
E5......................... <=200 5 2,306 m (1,138 m). 1,433 m (604 m).. 319 m (83 m).
E5......................... >200 1 N/A............... 725 m (184 m).... 297 m (38 m).
E5......................... >200 5 1,861 m (965 m)... 1,000 m (415 m).. 380 m (70 m).
E5......................... >200 20 3,944 m (1,014 m). 2,618 m (614 m).. 747 m (112 m).
E6......................... <=200 1 N/A............... 1,597 m (1,167 m) 485 m (63 m).
E6......................... <=200 15 4,916 m (981 m)... 3,605 m (763 m).. 1,433 m (181 m).
E6......................... >200 1 N/A............... 1,250 m (836 m).. 488 m (61 m).
E7......................... <=200 1 N/A............... 1,372 m (576 m).. 427 m (80 m).
E7......................... >200 1 N/A............... 1,458 m (1,037 m) 429 m (82 m).
E8......................... <=200 1 N/A............... 2,013 m (388 m).. 652 m (83 m).
E8......................... >200 1 N/A............... 1,985 m (376 m).. 643 m (82 m).
E9......................... <=200 1 N/A............... 2,528 m (1,170 m) 689 m (85 m).
E9......................... >200 1 N/A............... 2,183 m (938 m).. 692 m (84 m).
E10........................ <=200 1 N/A............... 3,220 m (660 m).. 841 m (112 m).
E10........................ >200 1 N/A............... 3,203 m (664 m).. 836 m (122 m).
E11........................ <=200 1 N/A............... 7,977 m (2,054 m) 1,468 m (173 m).
E11........................ >200 1 N/A............... 7,750 m (3,163 m) 1,570 m (266 m).
E12........................ <=200 1 N/A............... 3,844 m (1,097 m) 903 m (163 m).
E12........................ >200 1 N/A............... 3,453 m (1,050 m) 979 m (170 m).
E13........................ <=200 1 N/A............... 4,542 m (1,609 m) 2,757 m (1,128
m).
E16........................ >200 1 N/A............... 5,194 m (1,347 m) 2,667 m (513 m).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Behavioral response criteria are applied to explosive clusters >1. The values listed
for TTS and AUD INJ are the greater of the respective SPL and SEL ranges. Median ranges are shown with
standard deviation (SD) in parentheses. The Action Proponents split the LF functional hearing group into LF
and VLF based on Houser et al. (2024). NMFS updated acoustic technical guidance (NMFS, 2024) does not include
these data but we have included the VLF group here for reference. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2
(>0.25-0.5 lbs (0.113-0.23 kg)), E3 (>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10
lbs (2.27-4.54 kg)), E6 (>10-20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-27.2 kg)), E8 (>60-100 lbs (27.2-
45.4 kg)), E9 (>100-250 lbs (45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)),
E12 (>675-1,000 lbs (306-454 kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

Table 33--High-Frequency Cetacean Ranges to Effects for Explosives
----------------------------------------------------------------------------------------------------------------
Range to
Bin Depth (m) Cluster size behavioral Range to TTS (SD) Range to AUD INJ
disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
E1......................... <=200 1 N/A............... 91 m (18 m)...... 42 m (2 m).
E1......................... <=200 5 260 m (90 m)...... 180 m (49 m)..... 42 m (2 m).
E1......................... <=200 25 479 m (201 m)..... 316 m (122 m).... 85 m (17 m).
E1......................... <=200 50 497 m (182 m)..... 367 m (101 m).... 110 m (8 m).
E1......................... >200 1 N/A............... 90 m (3 m)....... 42 m (2 m).
E1......................... >200 5 280 m (29 m)...... 180 m (9 m)...... 42 m (2 m).
E1......................... >200 25 490 m (109 m)..... 310 m (46 m)..... 85 m (3 m).
E1......................... >200 50 800 m (176 m)..... 500 m (80 m)..... 110 m (4 m).
E2......................... <=200 1 N/A............... 122 m (12 m)..... 57 m (6 m).
E2......................... >200 1 N/A............... 122 m (12 m)..... 57 m (7 m).
E3......................... <=200 1 N/A............... 181 m (48 m)..... 93 m (4 m).
E3......................... <=200 5 491 m (183 m)..... 321 m (110 m).... 93 m (4 m).
E3......................... <=200 25 847 m (281 m)..... 582 m (182 m).... 154 m (43 m).
E3......................... >200 1 N/A............... 180 m (15 m)..... 93 m (5 m).
E3......................... >200 5 538 m (106 m)..... 330 m (46 m)..... 93 m (5 m).
E3......................... >200 25 986 m (258 m)..... 725 m (173 m).... 160 m (6 m).
E4......................... <=200 1 N/A............... 356 m (106 m).... 135 m (34 m).

[[Page 32223]]

E4......................... >200 1 N/A............... 282 m (35 m)..... 132 m (19 m).
E5......................... <=200 1 N/A............... 294 m (137 m).... 151 m (17 m).
E5......................... <=200 5 812 m (233 m)..... 513 m (166 m).... 151 m (17 m).
E5......................... >200 1 N/A............... 260 m (25 m)..... 149 m (14 m).
E5......................... >200 5 794 m (213 m)..... 500 m (98 m)..... 149 m (14 m).
E5......................... >200 20 1,250 m (299 m)... 875 m (178 m).... 220 m (17 m).
E6......................... <=200 1 N/A............... 455 m (218 m).... 213 m (28 m).
E6......................... <=200 15 1,624 m (167 m)... 1,223 m (117 m).. 427 m (47 m).
E6......................... >200 1 N/A............... 403 m (50 m)..... 216 m (26 m).
E7......................... <=200 1 N/A............... 422 m (93 m)..... 237 m (42 m).
E7......................... >200 1 N/A............... 450 m (154 m).... 236 m (44 m).
E8......................... <=200 1 N/A............... 621 m (71 m)..... 334 m (32 m).
E8......................... >200 1 N/A............... 610 m (70 m)..... 332 m (32 m).
E9......................... <=200 1 N/A............... 646 m (99 m)..... 378 m (48 m).
E9......................... >200 1 N/A............... 701 m (160 m).... 381 m (46 m).
E10........................ <=200 1 N/A............... 830 m (142 m).... 482 m (76 m).
E10........................ >200 1 N/A............... 820 m (164 m).... 481 m (73 m).
E11........................ <=200 1 N/A............... 1,271 m (157 m).. 699 m (70 m).
E11........................ >200 1 N/A............... 1,325 m (194 m).. 738 m (88 m).
E12........................ <=200 1 N/A............... 1,005 m (226 m).. 650 m (114 m).
E12........................ >200 1 N/A............... 1,008 m (219 m).. 632 m (109 m).
E13........................ <=200 1 N/A............... 5,569 m (4,190 m) 2,701 m (4,433
m).
E16........................ >200 1 N/A............... 3,778 m (8,655 m) 1,882 m (7,911 m)
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Behavioral response criteria are applied to explosive clusters >1. The values listed
for TTS and AUD INJ are the greater of the respective SPL and SEL ranges. Median ranges are shown with
standard deviation (SD) in parentheses. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2 (>0.25-0.5 lbs (0.113-0.23
kg)), E3 (>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10 lbs (2.27-4.54 kg)), E6 (>10-
20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-27.2 kg)), E8 (>60-100 lbs (27.2-45.4 kg)), E9 (>100-250 lbs
(45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)), E12 (>675-1,000 lbs (306-454
kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

Table 34--Very High-Frequency Cetacean Ranges to Effects for Explosives
----------------------------------------------------------------------------------------------------------------
Range to
Bin Depth (m) Cluster size behavioral Range to TTS (SD) Range to AUD INJ
disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
E1......................... <=200 1 N/A............... 1,034 m8 (156 m). 662 m (87 m).
E1......................... <=200 5 1,778 m (1,398 m). 1,250 m (1,056 m) 662 m (87 m).
E1......................... <=200 25 2,667 m (1,883 m). 1,965 m (1,556 m) 835 m (577 m).
E1......................... <=200 50 4,056 m (2,398 m). 2,917 m (2,027 m) 924 m (695 m).
E1......................... >200 1 N/A............... 1,500 m (413 m).. 646 m (85 m).
E1......................... >200 5 2,500 m (1,219 m). 2,000 m (708 m).. 729 m (105 m).
E1......................... >200 25 3,972 m (2,279 m). 2,861 m (1,520 m) 1,250 m (251 m).
E1......................... >200 50 3,806 m (2,522 m). 3,035 m (1,737 m) 1,000 m (428 m).
E2......................... <=200 1 N/A............... 1,397 m (241 m).. 798 m (107 m).
E2......................... >200 1 N/A............... 1,431 m (235 m).. 799 m (104 m).
E3......................... <=200 1 N/A............... 2,100 m (410 m).. 1,350 m (173 m).
E3......................... <=200 5 2,708 m (1,843 m). 2,100 m (410 m).. 1,350 m (173 m).
E3......................... <=200 25 3,171 m (2,026 m). 2,500 m (1,738 m) 1,350 m (173 m).
E3......................... >200 1 N/A............... 2,250 m (913 m).. 1,352 m (167 m).
E3......................... >200 5 3,708 m (2,026 m). 2,750 m (1,330 m) 1,352 m (167 m).
E3......................... >200 25 3,000 m (2,086 m). 2,500 m (1,596 m) 1,471 m (526 m).
E4......................... <=200 1 N/A............... 3,216 m (516 m).. 2,189 m (251 m).
E4......................... >200 1 N/A............... 3,321 m (522 m).. 2,250 m (256 m).
E5......................... <=200 1 N/A............... 2,229 m (447 m).. 1,472 m (260 m).
E5......................... <=200 5 3,931 m (2,098 m). 3,322 m (1,800 m) 1,642 m (786 m).
E5......................... >200 1 N/A............... 2,264 m (1,091 m) 1,415 m (254 m).
E5......................... >200 5 4,924 m (3,027 m). 3,681 m (2,102 m) 1,750 m (457 m).
E5......................... >200 20 11,958 m (2,934 m) 8,125 m (2,005 m) 2,250 m (555 m).
E6......................... <=200 1 N/A............... 3,622 m (828 m).. 2,385 m (514 m).
E6......................... <=200 15 4,411 m (761 m)... 3,945 m (631 m).. 2,633 m (362 m).
E6......................... >200 1 N/A............... 3,667 m (779 m).. 2,423 m (488 m).
E7......................... <=200 1 N/A............... 4,083 m (767 m).. 2,750 m (478 m).
E7......................... >200 1 N/A............... 4,458 m (1,831 m) 2,838 m (465 m).
E8......................... <=200 1 N/A............... 7,163 m (3,017 m) 3,215 m (825 m).
E8......................... >200 1 N/A............... 6,023 m (2,763 m) 3,069 m (731 m).
E9......................... <=200 1 N/A............... 5,469 m (992 m).. 3,194 m (633 m).
E9......................... >200 1 N/A............... 5,319 m (1,041 m) 3,092 m (601 m).
E10........................ <=200 1 N/A............... 7,028 m (1,433 m) 4,067 m (867 m).
E10........................ >200 1 N/A............... 6,974 m (1,482 m) 4,000 m (825 m).

[[Page 32224]]

E11........................ <=200 1 N/A............... 27,993 m (6,335 16,304 m (5,256
m). m).
E11........................ >200 1 N/A............... 26,087 m (6,856 15,150 m (6,163
m). m).
E12........................ <=200 1 N/A............... 8,639 m (1,966 m) 4,514 m (1,389
m).
E12........................ >200 1 N/A............... 8,882 m (2,905 m) 4,812 m (1,608
m).
E13........................ <=200 1 N/A............... 11,222 m (3,196 4,931 m (1,169
m). m).
E16........................ >200 1 N/A............... 6,639 m (6,673 m) 2,257 m (1,560
m).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Behavioral response criteria are applied to explosive clusters >1. The values listed
for TTS and AUD INJ are the greater of the respective SPL and SEL ranges. Median ranges are shown with
standard deviation (SD) in parentheses. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2 (>0.25-0.5 lbs (0.113-0.23
kg)), E3 (>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10 lbs (2.27-4.54 kg)), E6 (>10-
20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-27.2 kg)), E8 (>60-100 lbs (27.2-45.4 kg)), E9 (>100-250 lbs
(45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)), E12 (>675-1,000 lbs (306-454
kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

Table 35--Phocid Carnivore in Water Ranges to Effects for Explosives
----------------------------------------------------------------------------------------------------------------
Range to
Bin Depth (m) Cluster size behavioral Range to TTS (SD) Range to AUD INJ
disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
E1......................... <=200 1 N/A............... 227 m (67 m)..... 83 m (6 m).
E1......................... <=200 5 673 m (210 m)..... 421 m (145 m).... 110 m (27 m).
E1......................... <=200 25 1,138 m (420 m)... 822 m (242 m).... 199 m (61 m).
E1......................... <=200 50 1,264 m (577 m)... 785 m (286 m).... 259 m (51 m).
E1......................... >200 1 N/A............... 260 m (41 m)..... 84 m (6 m).
E1......................... >200 5 675 m (179 m)..... 480 m (85 m)..... 110 m (4 m).
E1......................... >200 25 975 m (360 m)..... 725 m (209 m).... 230 m (20 m).
E1......................... >200 50 1,500 m (563 m)... 1,000 m (295 m).. 305 m (35 m).
E2......................... <=200 1 N/A............... 347 m (52 m)..... 110 m (15 m).
E2......................... >200 1 N/A............... 355 m (55 m)..... 112 m (16 m).
E3......................... <=200 1 N/A............... 490 m (227 m).... 188 m (13 m).
E3......................... <=200 5 1,221 m (433 m)... 837 m (245 m).... 209 m (59 m).
E3......................... <=200 25 1,969 m (787 m)... 1,428 m (468 m).. 397 m (113 m).
E3......................... >200 1 N/A............... 675 m (141 m).... 188 m (13 m).
E3......................... >200 5 1,250 m (396 m)... 917 m (205 m).... 240 m (20 m).
E3......................... >200 25 2,250 m (868 m)... 1,499 m (559 m).. 490 m (103 m).
E4......................... <=200 1 N/A............... 1,124 m (441 m).. 295 m (114 m).
E4......................... >200 1 N/A............... 900 m (114 m).... 283 m (59 m).
E5......................... <=200 1 N/A............... 748 m (445 m).... 301 m (45 m).
E5......................... <=200 5 1,917 m (829 m)... 1,258 m (431 m).. 311 m (85 m).
E5......................... >200 1 N/A............... 768 m (184 m).... 294 m (42 m).
E5......................... >200 5 1,611 m (814 m)... 1,000 m (379 m).. 370 m (60 m).
E5......................... >200 20 3,674 m (1,149 m). 1,750 m (581 m).. 664 m (82 m).
E6......................... <=200 1 N/A............... 1,108 m (704 m).. 431 m (79 m).
E6......................... <=200 15 3,584 m (735 m)... 2,786 m (457 m).. 1,048 m (152 m).
E6......................... >200 1 N/A............... 1,000 m (546 m).. 429 m (69 m).
E7......................... <=200 1 N/A............... 1,080 m (368 m).. 472 m (95 m).
E7......................... >200 1 N/A............... 1,250 m (545 m).. 471 m (96 m).
E8......................... <=200 1 N/A............... 1,780 m (552 m).. 646 m (90 m).
E8......................... >200 1 N/A............... 1,750 m (531 m).. 642 m (91 m).
E9......................... <=200 1 N/A............... 1,708 m (690 m).. 721 m (138 m).
E9......................... >200 1 N/A............... 1,604 m (628 m).. 711 m (128 m).
E10........................ <=200 1 N/A............... 2,078 m (579 m).. 839 m (162 m).
E10........................ >200 1 N/A............... 2,114 m (550 m).. 836 m (167 m).
E11........................ <=200 1 N/A............... 4,881 m (1,625 m) 1,433 m (588 m).
E11........................ >200 1 N/A............... 5,028 m (1,523 m) 1,556 m (568 m).
E12........................ <=200 1 N/A............... 2,489 m (848 m).. 1,020 m (322 m).
E12........................ >200 1 N/A............... 2,480 m (822 m).. 1,058 m (310 m).
E13........................ <=200 1 N/A............... 4,139 m (776 m).. 2,146 m (522 m).
E16........................ >200 1 N/A............... 2,389 m (840 m).. 1,361 m (528 m).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Behavioral response criteria are applied to explosive clusters >1. The values listed
for TTS and AUD INJ are the greater of the respective SPL and SEL ranges. Median ranges are shown with
standard deviation (SD) in parentheses. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2 (>0.25-0.5 lbs (0.113-0.23
kg)), E3 (>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10 lbs (2.27-4.54 kg)), E6 (>10-
20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-27.2 kg)), E8 (>60-100 lbs (27.2-45.4 kg)), E9 (>100-250 lbs
(45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)), E12 (>675-1,000 lbs (306-454
kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

[[Page 32225]]

Table 36--Otariid Carnivore in Water Ranges to Effects for Explosives
----------------------------------------------------------------------------------------------------------------
Range to
Bin Depth (m) Cluster size behavioral Range to TTS (SD) Range to AUD INJ
disturbance (SD) (SD)
----------------------------------------------------------------------------------------------------------------
E1......................... <=200 1 N/A............... 156 m (48 m)..... 41 m (2 m).
E1......................... <=200 5 424 m (170 m)..... 288 m (102 m).... 85 m (17 m).
E1......................... <=200 25 779 m (306 m)..... 543 m (198 m).... 140 m (45 m).
E1......................... <=200 50 835 m (454 m)..... 550 m (229 m).... 210 m (37 m).
E1......................... >200 1 N/A............... 190 m (25 m)..... 41 m (2 m).
E1......................... >200 5 450 m (78 m)...... 322 m (52 m)..... 85 m (4 m).
E1......................... >200 25 600 m (135 m)..... 480 m (93 m)..... 170 m (19 m).
E1......................... >200 50 769 m (133 m)..... 597 m (96 m)..... 230 m (30 m).
E2......................... <=200 1 N/A............... 258 m (39 m)..... 60 m (8 m).
E2......................... >200 1 N/A............... 261 m (41 m)..... 62 m (9 m).
E3......................... <=200 1 N/A............... 321 m (126 m).... 90 m (8 m).
E3......................... <=200 5 757 m (286 m)..... 532 m (185 m).... 140 m (42 m).
E3......................... <=200 25 1,306 m (572 m)... 903 m (358 m).... 260 m (91 m).
E3......................... >200 1 N/A............... 400 m (111 m).... 90 m (9 m).
E3......................... >200 5 675 m (135 m)..... 525 m (89 m)..... 170 m (19 m).
E3......................... >200 25 876 m (285 m)..... 674 m (158 m).... 300 m (52 m).
E4......................... <=200 1 N/A............... 764 m (196 m).... 122 m (36 m).
E4......................... >200 1 N/A............... 525 m (118 m).... 117 m (18 m).
E5......................... <=200 1 N/A............... 525 m (253 m).... 147 m (22 m).
E5......................... <=200 5 1,264 m (472 m)... 873 m (285 m).... 225 m (60 m).
E5......................... >200 1 N/A............... 440 m (77 m)..... 141 m (19 m).
E5......................... >200 5 758 m (197 m)..... 575 m (129 m).... 250 m (38 m).
E6......................... <=200 1 N/A............... 808 m (379 m).... 208 m (34 m).
E6......................... <=200 15 2,221 m (258 m)... 1,767 m (186 m).. 791 m (65 m).
E6......................... >200 1 N/A............... 565 m (265 m).... 215 m (31 m).
E7......................... <=200 1 N/A............... 694 m (244 m).... 200 m (46 m).
E7......................... >200 1 N/A............... 650 m (210 m).... 180 m (100 m).
E8......................... <=200 1 N/A............... 877 m (114 m).... 320 m (46 m).
E8......................... >200 1 N/A............... 846 m (118 m).... 314 m (46 m).
E9......................... <=200 1 N/A............... 929 m (361 m).... 317 m (40 m).
E9......................... >200 1 N/A............... 729 m (158 m).... 331 m (44 m).
E10........................ <=200 1 N/A............... 1,055 m (174 m).. 406 m (73 m).
E10........................ >200 1 N/A............... 1,014 m (222 m).. 413 m (71 m).
E11........................ <=200 1 N/A............... 1,764 m (212 m).. 717 m (86 m).
E11........................ >200 1 N/A............... 1,694 m (280 m).. 750 m (108 m).
E12........................ <=200 1 N/A............... 880 m (132 m).... 406 m (67 m).
E12........................ >200 1 N/A............... 854 m (152 m).... 418 m (71 m).
E13........................ <=200 1 N/A............... 4,514 m (1,620 m) 2,701 m (1,249
m).
E16........................ >200 1 N/A............... 3,708 m (7,259 m) 2,181 m (822 m).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. Behavioral response criteria are applied to explosive clusters >1. The values listed
for TTS and AUD INJ are the greater of the respective SPL and SEL ranges. Median ranges are shown with
standard deviation (SD) in parentheses. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2 (>0.25-0.5 lbs (0.113-0.23
kg)), E3 (>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10 lbs (2.27-4.54 kg)), E6 (>10-
20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-27.2 kg)), E8 (>60-100 lbs (27.2-45.4 kg)), E9 (>100-250 lbs
(45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)), E12 (>675-1,000 lbs (306-454
kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

Table 37--Explosive Ranges to Non-Auditory Injury and Mortality for All Marine Mammal Hearing Groups as a Function of Animal Mass
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bin Effect 10 kg (SD) 250 kg (SD) 1,000 kg (SD) 5,000 kg (SD) 25,000 kg (SD) 72,000 kg (SD)
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.............. Non-auditory 22 m.............. 21 m.............. 19 m............. 21 m............. 22 m............. 21 m
injury. (2 m)............. (2 m)............. (3 m)............ (2 m)............ (1 m)............ (1 m).
E1.............. Mortality......... 3 m............... 1 m............... 0 m.............. 0 m.............. 0 m.............. 0 m
(1 m)............. (1 m)............. (0 m)............ (0 m)............ (0 m)............ (0 m).
E2.............. Non-auditory 27 m.............. 26 m.............. 26 m............. 25 m............. 26 m............. 26 m
injury. (3 m)............. (3 m)............. (2 m)............ (2 m)............ (2 m)............ (1 m).
E2.............. Mortality......... 6 m............... 2 m............... 1 m.............. 0 m.............. 0 m.............. 0 m
(2 m)............. (2 m)............. (1 m)............ (0 m)............ (0 m)............ (0 m).
E3.............. Non-auditory 37 m.............. 38 m.............. 41 m............. 43 m............. 38 m............. 45 m
injury. (8 m)............. (8 m)............. (6 m)............ (3 m)............ (6 m)............ (1 m).
E3.............. Mortality......... 6 m............... 3 m............... 0 m.............. 0 m.............. 0 m.............. 0 m
(3 m)............. (2 m)............. (1 m)............ (0 m)............ (0 m)............ (0 m).
E4.............. Non-auditory 55 m.............. 57 m.............. 60 m............. 61 m............. 60 m............. 60 m
injury. (9 m)............. (9 m)............. (7 m)............ (7 m)............ (8 m)............ (6 m).
E4.............. Mortality......... 19 m.............. 9 m............... 4 m.............. 1 m.............. 1 m.............. 0 m
(6 m)............. (5 m)............. (1 m)............ (1 m)............ (0 m)............ (0 m).
E5.............. Non-auditory 76 m.............. 76 m.............. 76 m............. 75 m............. 75 m............. 76 m
injury. (4 m)............. (4 m)............. (4 m)............ (3 m)............ (4 m)............ (3 m).

[[Page 32226]]

E5.............. Mortality......... 16 m.............. 8 m............... 3 m.............. 2 m.............. 0 m.............. 0 m
(4 m)............. (3 m)............. (1 m)............ (1 m)............ (0 m)............ (0 m).
E6.............. Non-auditory 102 m............. 101 m............. 102 m............ 103 m............ 102 m............ 102 m
injury. (11 m)............ (11 m)............ (11 m)........... (10 m)........... (11 m)........... (9 m).
E6.............. Mortality......... 41 m.............. 19 m.............. 9 m.............. 6 m.............. 3 m.............. 2 m
(14 m)............ (8 m)............. (2 m)............ (1 m)............ (1 m)............ (0 m).
E7.............. Non-auditory 101 m............. 109 m............. 127 m............ 116 m............ 98 m............. 109 m
injury. (17 m)............ (21 m)............ (21 m)........... (16 m)........... (22 m)........... (13 m).
E7.............. Mortality......... 20 m.............. 10 m.............. 5 m.............. 3 m.............. 2 m.............. 1 m
(7 m)............. (4 m)............. (1 m)............ (1 m)............ (1 m)............ (0 m).
E8.............. Non-auditory 215 m............. 160 m............. 160 m............ 164 m............ 149 m............ 165 m
injury. (41 m)............ (10 m)............ (11 m)........... (5 m)............ (12 m)........... (4 m).
E8.............. Mortality......... 64 m.............. 30 m.............. 14 m............. 9 m.............. 4 m.............. 2 m
(27 m)............ (13 m)............ (3 m)............ (2 m)............ (1 m)............ (1 m).
E9.............. Non-auditory 345 m............. 192 m............. 194 m............ 204 m............ 180 m............ 211 m
injury. (75 m)............ (19 m)............ (21 m)........... (13 m)........... (18 m)........... (10 m).
E9.............. Mortality......... 156 m............. 22 m.............. 11 m............. 8 m.............. 4 m.............. 3 m
(47 m)............ (30 m)............ (2 m)............ (2 m)............ (1 m)............ (1 m).
E10............. Non-auditory 501 m............. 243 m............. 247 m............ 256 m............ 236 m............ 267 m
injury. (131 m)........... (127 m)........... (34 m)........... (28 m)........... (31 m)........... (23 m).
E10............. Mortality......... 258 m............. 67 m.............. 15 m............. 10 m............. 5 m.............. 4 m
(69 m)............ (64 m)............ (5 m)............ (2 m)............ (1 m)............ (0 m).
E11............. Non-auditory 652 m............. 367 m............. 374 m............ 361 m............ 363 m............ 371 m
injury. (125 m)........... (50 m)............ (48 m)........... (26 m)........... (27 m)........... (26 m).
E11............. Mortality......... 346 m............. 176 m............. 90 m............. 55 m............. 25 m............. 22 m
(71 m)............ (55 m)............ (8 m)............ (7 m)............ (3 m)............ (3 m).
E12............. Non-auditory 522 m............. 317 m............. 334 m............ 345 m............ 326 m............ 353 m
injury. (181 m)........... (41 m)............ (36 m)........... (32 m)........... (50 m)........... (2 m).
E12............. Mortality......... 309 m............. 136 m............. 19 m............. 12 m............. 7 m.............. 5 m
(85 m)............ (92 m)............ (1 m)............ (3 m)............ (1 m)............ (0 m).
E13............. Non-auditory 4,167 m........... 2,135 m........... 1,906 m.......... 2,073 m.......... 1,199 m.......... 953 m
injury. (1,504 m)......... (1,522 m)......... (1,156 m)........ (1,404 m)........ (1,046 m)........ (182 m).
E13............. Mortality......... 1,831 m........... 717 m............. 573 m............ 677 m............ 335 m............ 260 m
(783 m)........... (759 m)........... (572 m).......... (658 m).......... (410 m).......... (202 m).
E16............. Non-auditory 1,597 m........... 1,000 m........... 1,053 m.......... 1,069 m.......... 1,081 m.......... 975 m
injury. (484 m)........... (628 m)........... (205 m).......... (341 m).......... (257 m).......... (4 m).
E16............. Mortality......... 1,024 m........... 678 m............. 665 m............ 753 m............ 529 m............ 415 m
(225 m)........... (284 m)........... (214 m).......... (263 m).......... (277 m).......... (233 m).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Median ranges with standard deviation (SD) in parentheses. For non-auditory injury ranges, the greater of the respective ranges for 1 percent
chance of gastro-intestinal tract injury and 1 percent chance of injury. E1 (0.1-0.25 lbs (0.045-0.113 kg)), E2 (>0.25-0.5 lbs (0.113-0.23 kg)), E3
(>0.5-2.5 lbs (0.23-1.13 kg)), E4 (>2.5-5 lbs (1.13-2.27 kg)), E5 (>5-10 lbs (2.27-4.54 kg)), E6 (>10-20 lbs (4.54-9.07 kg)), E7 (>20-60 lbs (9.07-
27.2 kg)), E8 (>60-100 lbs (27.2-45.4 kg)), E9 (>100-250 lbs (45.4-113 kg)), E10 (>250-500 lbs (113-227 kg)), E11 (>500-675 lbs (227-306 kg)), E12
(>675-1,000 lbs (306-454 kg)), E13 (>1,000-1,740 lbs (454-789 kg)), E16 (10,000 lbs (4,536 kg)).

Marine Mammal Density

A quantitative analysis of impacts on a species or stock requires
data on their abundance and distribution that may be affected by
anthropogenic activities in the potentially impacted area. The most
appropriate metric for this type of analysis is density, which is the
number of animals present per unit area. Marine species density
estimation requires a significant amount of effort to both collect and
analyze data to produce a reasonable estimate. Unlike surveys for
terrestrial wildlife, many marine species spend much of their time
submerged and are not easily observed. In order to collect enough
sighting data to make reasonable density estimates, multiple
observations are required, often in areas that are not easily
accessible (e.g., far offshore). Ideally, marine mammal species
sighting data would be collected for the specific area and time period
(e.g., season) of interest and density estimates derived accordingly.
However, in many places, poor weather conditions and high sea states
prohibit the completion of comprehensive visual surveys.
For most cetacean species, abundance is estimated using line-
transect surveys or mark-recapture studies (e.g., Barlow, 2010; Barlow
and Forney, 2007; Calambokidis et al., 2008). This is the general
approach applied in estimating cetacean abundance in NMFS SARs.
Although the single value provides a good average estimate of abundance
(i.e., total number of individuals) for a specified area, it does not
provide information on the species distribution or concentrations
within that area, and it does not estimate density for other timeframes
or seasons that were not surveyed. More recently, spatial habitat
modeling has been used to estimate cetacean densities (e.g., Becker et
al., 2022a, Becker et al., 2022b, Becker et al., 2021, Becker et al.,
2020a; Becker et al., 2020b). These models estimate cetacean density as
a continuous function of habitat variables (e.g., sea surface
temperature, seafloor depth, etc.) and thus allow predictions of
cetacean densities on finer spatial scales than traditional line-
transect or mark recapture analyses, and for areas that have not been
surveyed. Within the geographic area that was modeled, densities can be
predicted wherever these habitat variables can be measured or
estimated.
Ideally, density data would be available for all species throughout
the Study Area year-round, in order to best

[[Page 32227]]

estimate the impacts of specified activities on marine species.
However, in many places, vessel availability, lack of funding,
inclement weather conditions, and high sea states prevent the
completion of comprehensive year-round surveys. Even with surveys that
are completed, poor conditions may result in lower sighting rates for
species that would typically be sighted with greater frequency under
favorable conditions. Lower sighting rates preclude having an
acceptably low uncertainty in the density estimates. A high level of
uncertainty, indicating a low level of confidence in the density
estimate, is typical for species that are rare or difficult to sight.
In areas where survey data are limited or non-existent, known or
inferred associations between marine habitat features and the likely
presence of specific species are sometimes used to predict densities in
the absence of actual animal sightings. Consequently, there is no
single source of density data for every area, species, and season
because of the fiscal costs, resources, and effort involved in
providing enough survey coverage to sufficiently estimate density.
To characterize the marine species density for large oceanic
regions, the Action Proponents review, critically assess, and
prioritize existing density estimates from multiple sources, requiring
the development of a systematic method for selecting the most
appropriate density estimate for each combination of species/stock,
area, and season. The selection and compilation of the best available
marine species density data resulted in the NMSDD, which includes
seasonal density values for every marine mammal species and stock
present within the HCTT Study Area. This database is described in the
``U.S. Navy Marine Species Density Database Phase IV for the Hawaii-
California Training and Testing Study Area'' technical report (U.S.
Department of the Navy, 2024), hereafter referred to as the Density
Technical Report. NMFS reviewed all marine mammal densities provided by
the Action Proponents prior to use in their acoustic analysis for the
current rulemaking process.
A variety of density data and density models are needed to develop
a density database that encompasses the entirety of the HCTT Study
Area. Because these data are collected using different methods with
varying amounts of accuracy and uncertainty, the Action Proponents have
developed a hierarchy to ensure the most accurate data are used when
available. The Density Technical Report describes these models in
detail and provides detailed explanations of the best available density
estimate for each species. The list below describes possible sources of
density data in order of preference:
1. Density spatial models are preferred and used when available
because they provide spatially-explicit density estimates (typically at
10 km by 10 km (5.4 nmi by 5.4 nmi) spatial resolution) throughout the
study area with the least amount of uncertainty). These models (see
Becker et al., 2022a, Becker et al., 2022b, Becker et al., 2021, Becker
et al., 2020a; Becker et al., 2020b, Becker et al., 2018, Forney et
al., 2015) predict spatial variability of animal density based on
habitat variables (e.g., sea surface temperature, seafloor depth,
etc.). Density spatial models are developed for areas, species, and,
when available, specific timeframes (e.g., months or seasons) with
sufficient survey data; therefore, these models cannot be used for
species with low numbers of sightings.
2. Stratified design-based density estimates use line-transect
survey data with the sampling area divided (i.e., stratified) into sub-
regions, and a density is derived for each sub-region (see Barlow,
2016; Barlow and Forney, 2007; Bradford et al., 2021). While
geographically stratified density estimates provide a better indication
of a species' distribution within the study area, the uncertainty is
typically high because each sub-region estimate is based on a smaller
stratified segment of the overall survey effort.
3. Design-based density estimations use line-transect survey data
collected from ship or aerial surveys designed to cover a specific
geographic area (see Carretta et al., 2024). These estimates use the
same survey data as stratified design-based estimates, but are not
segmented into sub-regions and instead provide one estimate for a
large, surveyed area.
When interpreting the results of the quantitative analysis, as
described in the Density Technical Report for the Phase III Atlantic
Fleet Training and Testing Study Area (U.S. Department of the Navy,
2017a), ``it is important to consider that even the best estimate of
marine species density is really a model representation of the values
of concentration where these animals might occur. Each model is limited
to the variables and assumptions considered by the original data source
provider. No mathematical model representation of any biological
population is perfect and with regards to marine species biodiversity,
any single model method will not completely explain the actual
distribution and abundance of marine mammal species. It is expected
that there would be anomalies in the results that need to be evaluated,
with independent information for each case, to support if we might
accept or reject a model or portions of the model.''
The Action Proponents' estimates of abundance (based on density
estimates used in the HCTT Study Area) utilize NMFS' SARs. For some
species, the stock assessment for a given species may exceed the Navy's
density prediction because those species' home range extends beyond the
study area boundaries. For other species, the stock assessment
abundance may be much less than the number of animals in the Navy's
modeling given that the HCTT Study Area extends beyond the U.S. waters
covered by the SAR abundance estimate. The primary source of density
estimates are geographically specific survey data and either peer-
reviewed line-transect estimates or habitat-based density models that
have been extensively validated to provide the most accurate estimates
possible.
NMFS coordinated with the Navy in the development of its take
estimates and concurs that the Navy's approach for density
appropriately utilizes the best available science. Later, in the
Preliminary Analysis and Negligible Impact Determination section, we
assess how the estimated take numbers compare to stock abundance in
order to better understand the potential number of individuals
impacted, and the rationale for which abundance estimate is used is
included there.

Estimated Take From Acoustic Stressors

The 2024 HCTT Draft EIS/OEIS considered all military readiness
activities proposed to occur in the HCTT Study Area that have the
potential to result in the MMPA defined take of marine mammals. The
Action Proponents determined that the four stressors below could result
in the incidental taking of marine mammals. NMFS has reviewed the
Action Proponents' data and analysis and determined that it is complete
and accurate and agrees that the following stressors have the potential
to result in takes by harassment of marine mammals from the specified
activities:
Acoustics (i.e., sonars and other transducers, air guns,
pile driving/extraction);
Explosives (i.e., explosive shock wave and sound, assumed
to encompass the risk due to fragmentation);
Land-based launch noise from missile and target launches
at SNI and weapons firing and launch noise at PMRF; and
Vessel strike.

[[Page 32228]]

Acoustic and explosive sources and land-based launch noise are
likely to result in incidental takes of marine mammals by harassment.
Vessel strikes have the potential to result in incidental take from
injury, serious injury, and/or mortality.
The quantitative analysis process used for the 2024 HCTT Draft EIS/
OEIS and the application to estimate potential exposures to marine
mammals resulting from acoustic and explosive stressors is detailed in
the Acoustic Impacts Technical Report.
Regarding how avoidance of loud sources is considered in the take
estimation, NAEMO does not simulate horizontal animat (i.e., a virtual
animal) movement during an event. However, NAEMO approximates marine
mammal avoidance of high sound levels due to exposure to sonars in a
one-dimensional calculation that scales how far an animat would be from
a sound source based on sensitivity to disturbance, swim speed, and
avoidance duration. This process reduces the SEL, defined as the
accumulation for a given animat, by reducing the received SPL of
individual exposures based on a spherical spreading calculation from
sources on each unique platform in an event. The onset of avoidance was
based on the behavioral response functions. Avoidance speeds and
durations were informed by a review of available exposure and baseline
data. This method captures a more accurate representation of avoidance
by using the received sound levels, distance to platform, and species-
specific criteria to calculate potential avoidance for each animat than
the approach used in Phase III. However, this avoidance method may
underestimate avoidance of long-duration sources with lower sound
levels because it triggers avoidance calculations based on the highest
modeled SPL received level exceeding p(0.5) on the BRF, rather than on
cumulative exposure. This is because initiation of the avoidance
calculation is based on the highest modeled SPL received level over
p(0.5) on the BRF. Please see section 4.4.2.2 of the Acoustic Impacts
Technical Report.
Regarding the consideration of mitigation effectiveness in the take
estimation, during military readiness activities, there is typically at
least one, if not numerous, support personnel involved in the activity
(e.g., range support personnel aboard a torpedo retrieval boat or
support aircraft). In addition to the Lookout posted for the purpose of
mitigation, these additional personnel observe and disseminate marine
species sighting information amongst the units participating in the
activity whenever possible as they conduct their primary mission
responsibilities. However, unlike in previous phases of HCTT, this
quantitative analysis does not reduce model-estimated impacts to
account for activity-based mitigation. While the activity-based
mitigation is not quantitatively included in the take estimates (which,
of note, would result in a reduction in the number of takes), table A-6
of appendix A of the application indicates the percentage of the
instances of take where an animal's closest point of approach was
within a mitigation zone and, therefore, AUD INJ could potentially be
mitigated. Note that these percentages do not account for other
factors, such as the sightability of a given species or viewing
conditions.
Unlike activity-based mitigation, in some cases, implementation of
the proposed geographic mitigation areas are incorporated into the
quantitative analysis. The extent to which the mitigation areas reduce
impacts on the affected species is addressed in the Preliminary
Analysis and Negligible Impact Determination section.
For additional information on the quantitative analysis process,
refer to the Acoustic Impacts Technical Report and sections 6 and 11 of
the application.
As a general matter, NMFS does not prescribe the methods for
estimating take for any applicant, but we review and ensure that
applicants use the best available science, and methodologies that are
logical and technically sound. Applicants may use different methods of
calculating take (especially when using models) and still get to a
result that is representative of the best available science and that
allows for a rigorous and accurate evaluation of the effects on the
affected populations. There are multiple pieces of the Navy's take
estimation methods--propagation models, animat movement models, and
behavioral thresholds, for example. NMFS evaluates the acceptability of
these pieces as they evolve and are used in different rules and impact
analyses. Some of the pieces of the Action Proponents' take estimation
process have been used in Navy incidental take rules since 2009 and
undergone multiple public comment processes; all of them have undergone
extensive internal Navy review, and all of them have undergone
comprehensive review by NMFS, which has sometimes resulted in
modifications to methods or models.
The Navy uses rigorous review processes (verification, validation,
and accreditation processes; peer and public review) to ensure the data
and methodology it uses represent the best available science. For
instance, NAEMO is the result of a NMFS-led Center for Independent
Experts review of the components used in earlier models. The acoustic
propagation component of NAEMO (titled CASS/GRAB) is accredited by the
Oceanographic and Atmospheric Master Library (OAML), and many of the
environmental variables used in NAEMO come from approved OAML databases
and are based on in-situ data collection. The animal density components
of NAEMO are base products of the NMSDD, which includes animal density
components that have been validated and reviewed by a variety of
scientists from NMFS Science Centers and academic institutions. Several
components of the model, for example, habitat-based density model
results for species off Hawaii and California have been published in
several peer-reviewed journals (Becker et al., 2020; Becker et al.,
2021; Becker et al., 2022a; Becker et al., 2022b). Additionally, NAEMO
simulation components underwent quality assurance and quality control
(commonly referred to as QA/QC) review and validation for model parts
such as the scenario builder, acoustic builder, scenario simulator,
etc., conducted by qualified statisticians and modelers to ensure
accuracy. Other models and methodologies have gone through similar
review processes.
In summary, we believe the Action Proponents' methods, including
the method for incorporating avoidance, are the most appropriate
methods for predicting AUD INJ, non-auditory injury, TTS, and
behavioral disturbance. But even with the consideration of avoidance,
given some of the more conservative components of the methodology
(e.g., the thresholds do not consider ear recovery between pulses), we
would describe the application of these methods as identifying the
maximum number of instances in which marine mammals would be reasonably
expected to be taken through AUD INJ, non-auditory injury, TTS, or
behavioral disturbance.
Based on the methods discussed in the previous sections and NAEMO,
the Action Proponents provided their take estimate and request for
authorization of takes incidental to the use of acoustic and explosive
sources for military readiness activities annually (based on the
maximum number of activities that could occur per 12-month period) and
over the 7-year period, as well as the Navy's take request for ship
shock trials, covered by the application. The following species/stocks
present in the HCTT Study Area were modeled by the Navy and estimated
to have 0 takes of

[[Page 32229]]

any type from any activity source: killer whale (Eastern North Pacific
Southern Resident stock) and spinner dolphin (Midway Atoll/Kure stock
and Pearl and Hermes stock). NMFS has reviewed the Action Proponents'
data, methodology, and analysis and determined that it is complete and
accurate. NMFS agrees that the estimates for incidental takes by
harassment from all sources requested for authorization are the maximum
number of instances in which marine mammals are reasonably expected to
be taken and that the takes by mortality requested for authorization
are for the maximum number of instances mortality or serious injury
could occur, as in the case of ship shock trials and vessel strikes.
Table 38, table 39, table 40, and table 41 summarize the maximum
annual and 7-year total amount and type of Level A harassment and Level
B harassment that NMFS concurs is reasonably expected to occur by
species and stock for Navy training activities, Navy testing
activities, Coast Guard training activities, and Army training
activities, respectively.

Table 38--Incidental Take Estimate by Stock Due to Acoustic and Explosive Sources During Navy Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual 7-year total 7-year total
Species Stock Level B Level A Maximum annual Level B Level A 7-year total
harassment harassment mortality harassment harassment mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 4,918 98 0 32,444 645 0
Pacific.
Gray Whale........................ Western North 48 1 0 305 2 0
Pacific.
Blue Whale........................ Central North 67 0 0 389 0 0
Pacific.
Blue Whale........................ Eastern North 2,716 17 0 14,681 84 0
Pacific.
Bryde's Whale..................... Eastern Tropical 179 2 0 1,041 5 0
Pacific.
Bryde's Whale..................... Hawaii.............. 306 2 0 1,809 10 0
Fin Whale......................... Hawaii.............. 59 0 0 334 0 0
Fin Whale......................... California/Oregon/ 7,409 28 0 37,629 144 0
Washington.
Humpback Whale.................... Central America/ 1,042 14 0 5,361 68 0
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 2,401 34 0 12,414 171 0
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 2,244 18 0 14,250 113 0
Minke Whale....................... Hawaii.............. 229 2 0 1,330 12 0
Minke Whale....................... California/Oregon/ 1,686 24 0 8,980 144 0
Washington.
Sei Whale......................... Hawaii.............. 200 1 0 1,146 2 0
Sei Whale......................... Eastern North 195 1 0 1,028 7 0
Pacific.
Sperm Whale....................... Hawaii.............. 1,296 1 0 7,829 1 0
Sperm Whale....................... California/Oregon/ 2,897 2 0 15,447 4 0
Washington.
Dwarf Sperm Whale................. Hawaii.............. 36,298 501 0 215,688 3,065 0
Dwarf Sperm Whale................. California/Oregon/ 4,329 50 0 22,647 271 0
Washington.
Pygmy Sperm Whale................. Hawaii.............. 36,722 518 0 217,948 3,153 0
Pygmy Sperm Whale................. California/Oregon/ 4,240 66 0 22,246 371 0
Washington.
Baird's Beaked Whale.............. California/Oregon/ 7,290 0 0 39,692 0 0
Washington.
Blainville's Beaked Whale......... Hawaii.............. 5,812 0 0 36,916 0 0
Goose-Beaked Whale................ Hawaii.............. 23,258 0 0 147,787 0 0
Goose-Beaked Whale................ California/Oregon/ 110,853 1 0 638,374 2 0
Washington.
Longman's Beaked Whale............ Hawaii.............. 14,051 1 0 89,592 4 0
Mesoplodont Beaked Whale.......... California/Oregon/ 64,655 1 0 371,374 2 0
Washington.
False Killer Whale................ Main Hawaiian 122 0 0 752 0 0
Islands Insular.
False Killer Whale................ Northwest Hawaiian 151 0 0 959 0 0
Islands.

[[Page 32230]]

False Killer Whale................ Hawaii Pelagic...... 1,371 0 0 8,293 0 0
False Killer Whale................ Baja California 2,127 1 0 11,552 1 0
Peninsula Mexico.
Killer Whale...................... Hawaii.............. 103 0 0 610 0 0
Killer Whale...................... Eastern North 545 3 0 3,310 21 0
Pacific Offshore.
Killer Whale...................... West Coast Transient 46 0 0 204 0 0
Melon-Headed Whale................ Hawaiian Islands.... 26,120 9 0 155,607 53 0
Melon-Headed Whale................ Kohala Resident 23 0 0 130 0 0
(Hawaii).
Pygmy Killer Whale................ Hawaii.............. 7,428 2 0 44,514 7 0
Pygmy Killer Whale................ California--Baja 477 0 0 2,705 0 0
California
Peninsula Mexico.
Short-Finned Pilot Whale.......... Hawaii.............. 13,851 3 0 85,991 18 0
Short-Finned Pilot Whale.......... California/Oregon/ 1,995 9 1 11,567 54 4
Washington.
Bottlenose Dolphin................ Maui Nui............ 189 0 0 1,301 0 0
Bottlenose Dolphin................ Hawaii Island....... 6 0 0 25 0 0
Bottlenose Dolphin................ Hawaii Pelagic...... 37,546 18 1 252,429 123 2
Bottlenose Dolphin................ Kaua[revaps]i/ 1,179 0 0 7,728 0 0
Ni[revaps]ihau.
Bottlenose Dolphin................ O[revaps]ahu........ 6,789 5 1 47,410 29 1
Bottlenose Dolphin................ California Coastal.. 516 7 0 3,521 42 0
Bottlenose Dolphin................ California/Oregon/ 16,938 13 0 94,638 74 0
Washington Offshore.
Fraser's Dolphin.................. Hawaii.............. 30,371 5 0 184,274 26 0
Long-Beaked Common Dolphin........ California.......... 102,352 113 3 583,062 722 15
Northern Right Whale Dolphin...... California/Oregon/ 35,313 15 0 170,387 64 0
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 41,928 33 1 209,903 188 1
Washington.
Pantropical Spotted Dolphin....... Maui Nui............ 830 2 0 5,549 10 0
Pantropical Spotted Dolphin....... Hawaii Island....... 4,974 5 0 29,501 23 0
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 36,298 13 0 219,400 67 0
Pantropical Spotted Dolphin....... O[revaps]ahu........ 5,618 5 0 39,051 21 0
Pantropical Spotted Dolphin....... Baja California 82,440 43 1 448,311 224 1
Peninsula Mexico.
Risso's Dolphin................... Hawaii.............. 5,380 1 0 32,054 1 0
Risso's Dolphin................... California/Oregon/ 25,085 15 0 140,377 98 0
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 80,173 27 1 497,078 157 1
Short-Beaked Common Dolphin....... California/Oregon/ 1,428,183 694 13 7,867,127 4,036 91
Washington.
Spinner Dolphin................... Hawaii Pelagic...... 3,781 1 0 22,583 3 0
Spinner Dolphin................... Hawaii Island....... 97 1 0 562 1 0
Spinner Dolphin................... Kaua[revaps]i/ 3,528 1 0 23,147 5 0
Ni[revaps]ihau.
Spinner Dolphin................... O[revaps]ahu/4 991 1 0 6,922 2 0
Islands Region.
Striped Dolphin................... Hawaii Pelagic...... 31,260 8 0 186,357 43 0
Striped Dolphin................... California/Oregon/ 110,641 37 1 600,412 193 1
Washington.
Dall's Porpoise................... California/Oregon/ 43,844 708 0 218,178 3,727 0
Washington.
Harbor Porpoise................... Monterey Bay........ 1,314 0 0 5,627 0 0
Harbor Porpoise................... Morro Bay........... 3,883 11 0 23,051 71 0
Harbor Porpoise................... Northern California/ 357 0 0 1,576 0 0
Southern Oregon.

[[Page 32231]]

Harbor Porpoise................... San Francisco/ 6,920 24 0 30,248 164 0
Russian River.
California Sea Lion............... U.S................. 876,054 532 4 4,997,524 3,406 22
Guadalupe Fur Seal................ Mexico.............. 295,304 37 1 1,598,780 194 1
Northern Fur Seal................. Eastern Pacific..... 29,250 3 0 134,187 10 0
Northern Fur Seal................. California.......... 19,649 3 0 90,918 9 0
Steller Sea Lion.................. Eastern............. 524 3 0 2,470 13 0
Harbor Seal....................... California.......... 16,662 243 1 98,994 1,536 7
Hawaiian Monk Seal................ Hawaii.............. 748 4 0 5,065 18 0
Northern Elephant Seal............ California Breeding. 68,627 49 0 351,382 284 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted
dolphin, and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density
estimates were derived to support the Navy's analysis.

Table 39--Incidental Take Estimate by Stock Due to Acoustic and Explosive Source During Navy Testing
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual 7-year total 7-year total
Species Stock Level B Level A Maximum annual Level B Level A 7-year total
harassment harassment mortality harassment harassment mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 11,777 69 0 54,745 365 0
Pacific.
Gray Whale........................ Western North 120 1 0 545 3 0
Pacific.
Blue Whale........................ Central North 24 1 0 134 2 0
Pacific.
Blue Whale........................ Eastern North 1,836 10 0 10,002 66 0
Pacific.
Bryde's Whale..................... Eastern Tropical 142 3 0 828 9 0
Pacific.
Bryde's Whale..................... Hawaii.............. 99 1 0 531 1 0
Fin Whale......................... Hawaii.............. 25 1 0 145 1 0
Fin Whale......................... California/Oregon/ 6,030 27 0 30,497 156 0
Washington.
Humpback Whale.................... Central America/ 839 5 0 4,492 28 0
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 2,033 10 0 10,859 49 0
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 779 6 0 4,627 38 0
Minke Whale....................... Hawaii.............. 64 1 0 351 1 0
Minke Whale....................... California/Oregon/ 1,300 8 0 7,088 49 0
Washington.
Sei Whale......................... Hawaii.............. 52 1 0 287 3 0
Sei Whale......................... Eastern North 106 2 0 579 2 0
Pacific.
Sperm Whale....................... Hawaii.............. 346 0 0 1,745 0 0
Sperm Whale....................... California/Oregon/ 966 1 0 4,963 1 0
Washington.
Dwarf Sperm Whale................. Hawaii.............. 8,443 399 0 43,341 1,941 0
Dwarf Sperm Whale................. California/Oregon/ 1,283 43 0 7,101 245 0
Washington.
Pygmy Sperm Whale................. Hawaii.............. 8,603 402 0 44,150 1,966 0
Pygmy Sperm Whale................. California/Oregon/ 1,325 41 0 7,289 238 0
Washington.
Baird's Beaked Whale.............. California/Oregon/ 2,830 0 0 16,079 0 0
Washington.
Blainville's Beaked Whale......... Hawaii.............. 1,704 0 0 8,917 0 0

[[Page 32232]]

Goose-Beaked Whale................ Hawaii.............. 6,956 0 0 36,245 0 0
Goose-Beaked Whale................ California/Oregon/ 55,310 1 0 296,069 2 0
Washington.
Longman's Beaked Whale............ Hawaii.............. 4,118 0 0 21,544 0 0
Mesoplodont Beaked Whale.......... California/Oregon/ 27,768 1 0 146,662 4 0
Washington.
False Killer Whale................ Main Hawaiian 43 0 0 230 0 0
Islands Insular.
False Killer Whale................ Northwest Hawaiian 38 0 0 197 0 0
Islands.
False Killer Whale................ Hawaii Pelagic...... 287 1 0 1,489 1 0
False Killer Whale................ Baja California 393 0 0 2,226 0 0
Peninsula Mexico.
Killer Whale...................... Hawaii.............. 22 0 0 113 0 0
Killer Whale...................... Eastern North 477 1 0 2,772 2 0
Pacific Offshore.
Killer Whale...................... West Coast Transient 8 0 0 52 0 0
Melon-Headed Whale................ Hawaiian Islands.... 5,110 3 0 26,599 14 0
Melon-Headed Whale................ Kohala Resident 31 0 0 195 0 0
(Hawaii).
Pygmy Killer Whale................ Hawaii.............. 1,410 1 0 7,152 1 0
Pygmy Killer Whale................ California--Baja 315 0 0 1,635 0 0
California
Peninsula Mexico.
Short-Finned Pilot Whale.......... Hawaii.............. 3,367 2 0 18,188 5 0
Short-Finned Pilot Whale.......... California/Oregon/ 2,274 2 0 12,896 2 0
Washington.
Bottlenose Dolphin................ Maui Nui............ 137 0 0 850 0 0
Bottlenose Dolphin................ Hawaii Island....... 3 0 0 19 0 0
Bottlenose Dolphin................ Hawaii Pelagic...... 5,731 6 0 34,450 39 0
Bottlenose Dolphin................ Kaua[revaps]i/ 281 0 0 1,586 0 0
Ni[revaps]ihau.
Bottlenose Dolphin................ O[revaps]ahu........ 443 1 0 2,965 1 0
Bottlenose Dolphin................ California Coastal.. 832 0 0 5,228 0 0
Bottlenose Dolphin................ California/Oregon/ 10,999 2 0 62,160 9 0
Washington Offshore.
Fraser's Dolphin.................. Hawaii.............. 5,086 1 0 26,111 2 0
Long-Beaked Common Dolphin........ California.......... 193,599 39 1 1,215,256 230 2
Northern Right Whale Dolphin...... California/Oregon/ 9,950 6 1 51,898 32 1
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 27,035 9 1 149,417 54 1
Washington.
Pantropical Spotted Dolphin....... Maui Nui............ 1,542 2 0 9,642 8 0
Pantropical Spotted Dolphin....... Hawaii Island....... 1,026 2 0 5,919 2 0
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 7,862 4 0 41,161 12 0
Pantropical Spotted Dolphin....... O[revaps]ahu........ 807 1 0 5,142 2 0
Pantropical Spotted Dolphin....... Baja California 14,695 4 1 83,941 15 1
Peninsula Mexico.
Risso's Dolphin................... Hawaii.............. 1,143 2 0 5,746 3 0
Risso's Dolphin................... California/Oregon/ 18,560 6 0 99,161 27 0
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 16,289 7 1 87,872 37 1
Short-Beaked Common Dolphin....... California/Oregon/ 731,713 182 5 3,869,698 1,037 16
Washington.
Spinner Dolphin................... Hawaii Pelagic...... 739 1 0 3,791 1 0
Spinner Dolphin................... Hawaii Island....... 13 0 0 82 0 0
Spinner Dolphin................... Kaua[revaps]i/ 918 1 0 5,187 1 0
Ni[revaps]ihau.

[[Page 32233]]

Spinner Dolphin................... O[revaps]ahu/4 210 0 0 1,283 0 0
Islands Region.
Striped Dolphin................... Hawaii Pelagic...... 6,270 2 0 31,482 7 0
Striped Dolphin................... California/Oregon/ 21,982 7 0 118,342 38 0
Washington.
Dall's Porpoise................... California/Oregon/ 15,363 528 0 84,387 3,056 0
Washington.
Harbor Porpoise................... Monterey Bay........ 865 0 0 5,307 0 0
Harbor Porpoise................... Morro Bay........... 490 77 0 3,265 519 0
Harbor Porpoise................... Northern California/ 124 0 0 763 0 0
Southern Oregon.
Harbor Porpoise................... San Francisco/ 3,038 2 0 18,641 5 0
Russian River.
California Sea Lion............... U.S................. 997,758 191 1 5,449,070 1,166 5
Guadalupe Fur Seal................ Mexico.............. 48,392 17 0 275,065 106 0
Northern Fur Seal................. Eastern Pacific..... 3,311 9 0 20,183 45 0
Northern Fur Seal................. California.......... 1,894 7 0 11,495 38 0
Steller Sea Lion.................. Eastern............. 471 0 0 2,854 0 0
Harbor Seal....................... California.......... 54,180 18 0 287,858 106 0
Hawaiian Monk Seal................ Hawaii.............. 139 2 0 802 7 0
Northern Elephant Seal............ California Breeding. 48,052 61 0 262,329 360 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted
dolphin, and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density
estimates were derived to support the Navy's analysis.

Table 40--Incidental Take Estimate by Stock Due to Acoustic and Explosive Sources During Coast Guard Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual 7-year total 7-year total
Species Stock Level B Level A Maximum annual Level B Level A 7-year total
harassment harassment mortality harassment harassment mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 16 0 0 103 0 0
Pacific.
Gray Whale........................ Western North 1 0 0 2 0 0
Pacific.
Blue Whale........................ Central North 1 0 0 1 0 0
Pacific.
Blue Whale........................ Eastern North 19 0 0 125 0 0
Pacific.
Bryde's Whale..................... Eastern Tropical 1 0 0 5 0 0
Pacific.
Bryde's Whale..................... Hawaii.............. 2 0 0 13 0 0
Fin Whale......................... Hawaii.............. 2 0 0 8 0 0
Fin Whale......................... California/Oregon/ 62 0 0 432 0 0
Washington.
Humpback Whale.................... Central America/ 7 0 0 45 0 0
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 15 0 0 97 0 0
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 7 0 0 46 0 0
Minke Whale....................... Hawaii.............. 2 0 0 14 0 0
Minke Whale....................... California/Oregon/ 7 0 0 48 0 0
Washington.
Sei Whale......................... Hawaii.............. 1 0 0 4 0 0
Sei Whale......................... Eastern North 1 0 0 4 0 0
Pacific.
Sperm Whale....................... Hawaii.............. 7 0 0 45 0 0
Sperm Whale....................... California/Oregon/ 28 0 0 196 0 0
Washington.
Dwarf Sperm Whale................. Hawaii.............. 386 3 0 2,695 13 0
Dwarf Sperm Whale................. California/Oregon/ 52 1 0 345 1 0
Washington.
Pygmy Sperm Whale................. Hawaii.............. 354 1 0 2,469 1 0
Pygmy Sperm Whale................. California/Oregon/ 50 0 0 333 0 0
Washington.
Baird's Beaked Whale.............. California/Oregon/ 54 0 0 378 0 0
Washington.
Blainville's Beaked Whale......... Hawaii.............. 25 0 0 170 0 0
Goose-Beaked Whale................ Hawaii.............. 143 0 0 1,001 0 0
Goose-Beaked Whale................ California/Oregon/ 653 0 0 4,569 0 0
Washington.
Longman's Beaked Whale............ Hawaii.............. 145 0 0 1,013 0 0

[[Page 32234]]

Mesoplodont Beaked Whale.......... California/Oregon/ 416 0 0 2,902 0 0
Washington.
False Killer Whale................ Main Hawaiian 4 0 0 27 0 0
Islands Insular.
False Killer Whale................ Northwest Hawaiian 2 0 0 9 0 0
Islands.
False Killer Whale................ Hawaii Pelagic...... 12 0 0 83 0 0
False Killer Whale................ Baja California 17 1 0 110 1 0
Peninsula Mexico.
Killer Whale...................... Hawaii.............. 2 0 0 10 0 0
Killer Whale...................... Eastern North 1 0 0 7 0 0
Pacific Offshore.
Killer Whale...................... West Coast Transient 1 0 0 5 0 0
Melon-Headed Whale................ Hawaiian Islands.... 224 0 0 1,559 0 0
Pygmy Killer Whale................ Hawaii.............. 56 0 0 390 0 0
Pygmy Killer Whale................ California--Baja 3 0 0 18 0 0
California
Peninsula Mexico.
Short-Finned Pilot Whale.......... Hawaii.............. 83 0 0 578 0 0
Short-Finned Pilot Whale.......... California/Oregon/ 10 0 0 69 0 0
Washington.
Bottlenose Dolphin................ Hawaii Pelagic...... 33 0 0 226 0 0
Bottlenose Dolphin................ California Coastal.. 2 0 0 12 0 0
Bottlenose Dolphin................ California/Oregon/ 121 0 0 830 0 0
Washington Offshore.
Fraser's Dolphin.................. Hawaii.............. 18 0 0 114 0 0
Long-Beaked Common Dolphin........ California.......... 927 0 0 6,475 0 0
Northern Right Whale Dolphin...... California/Oregon/ 251 0 0 1,754 0 0
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 247 0 0 1,729 0 0
Washington.
Pantropical Spotted Dolphin....... Hawaii Island....... 24 0 0 164 0 0
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 227 0 0 1,580 0 0
Pantropical Spotted Dolphin....... O[revaps]ahu........ 1 0 0 7 0 0
Pantropical Spotted Dolphin....... Baja California 491 0 0 3,429 0 0
Peninsula Mexico.
Risso's Dolphin................... Hawaii.............. 35 0 0 240 0 0
Risso's Dolphin................... California/Oregon/ 188 0 0 1,309 0 0
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 406 0 0 2,838 0 0
Short-Beaked Common Dolphin....... California/Oregon/ 9,658 1 0 67,598 2 0
Washington.
Spinner Dolphin................... Hawaii Pelagic...... 24 0 0 165 0 0
Striped Dolphin................... Hawaii Pelagic...... 249 0 0 1,738 0 0
Striped Dolphin................... California/Oregon/ 776 0 0 5,420 0 0
Washington.
Dall's Porpoise................... California/Oregon/ 412 1 0 2,867 3 0
Washington.
Harbor Porpoise................... San Francisco/ 2 0 0 11 0 0
Russian River.
California Sea Lion............... U.S................. 14,937 0 0 104,545 0 0
Guadalupe Fur Seal................ Mexico.............. 3,857 0 0 26,989 0 0
Northern Fur Seal................. Eastern Pacific..... 634 0 0 4,426 0 0
Northern Fur Seal................. California.......... 555 0 0 3,885 0 0
Steller Sea Lion.................. Eastern............. 4 0 0 22 0 0
Harbor Seal....................... California.......... 141 0 0 977 0 0
Hawaiian Monk Seal................ Hawaii.............. 1 0 0 5 0 0
Northern Elephant Seal............ California Breeding. 1,795 1 0 12,549 1 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted
dolphin, and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density
estimates were derived to support the Navy's analysis.

Table 41--Incidental Take Estimate by Stock Due to Acoustic and Explosive Sources During Navy Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual 7-year total 7-year total
Species Stock Level B Level A Maximum annual Level B Level A 7-year total
harassment harassment mortality harassment harassment mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bryde's Whale..................... Hawaii.............. 2 0 0 3 0 0
Humpback Whale.................... Hawaii.............. 4 0 0 22 0 0
Minke Whale....................... Hawaii.............. 1 0 0 3 0 0
Dwarf Sperm Whale................. Hawaii.............. 97 12 0 677 84 0
Pygmy Sperm Whale................. Hawaii.............. 108 15 0 755 101 0
Blainville's Beaked Whale......... Hawaii.............. 1 0 0 1 0 0
Goose-Beaked Whale................ Hawaii.............. 2 0 0 6 0 0
Longman's Beaked Whale............ Hawaii.............. 2 0 0 3 0 0
Melon-Headed Whale................ Hawaiian Islands.... 2 1 0 8 1 0
Melon-Headed Whale................ Kohala Resident 2 0 0 7 0 0
(Hawaii).

[[Page 32235]]

Pygmy Killer Whale................ Hawaii.............. 1 0 0 3 0 0
Short-Finned Pilot Whale.......... Hawaii.............. 3 2 0 15 3 0
Bottlenose Dolphin................ Hawaii Pelagic...... 3 1 0 14 1 0
Fraser's Dolphin.................. Hawaii.............. 5 2 0 27 6 0
Pantropical Spotted Dolphin....... Maui Nui............ 1 0 0 1 0 0
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 3 2 0 14 2 0
Risso's Dolphin................... Hawaii.............. 0 1 0 0 1 0
Rough-Toothed Dolphin............. Hawaii.............. 5 2 0 31 2 0
Striped Dolphin................... Hawaii Pelagic...... 3 2 0 17 2 0
Hawaiian Monk Seal................ Hawaii.............. 1 0 0 3 0 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted
dolphin, and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density
estimates were derived to support the Navy's analysis.

Estimated Take From Sonar and Other Transducers
Table 42, table 43, and table 44 provide estimated effects from
sonar and other transducers, including the comparative amounts of TTS
and behavioral disturbance for each species and stock annually, noting
that if a modeled marine mammal was ``taken'' through exposure to both
TTS and behavioral disturbance in the model, it was recorded as a TTS.
Of note, a higher proportion of the takes by Level B harassment of
mysticetes include the potential for TTS (as compared to other taxa and
prior rules) due to a combination of the fact that mysticetes are
relatively less sensitive to behavioral disturbance and the number of
auditory impacts from sonar (both TTS and AUD INJ) have increased for
some species since the Phase III analysis (84 FR 70712, December 23,
2019) largely due to changes in how avoidance was modeled; for some
stocks, changes in densities in areas that overlap activities have also
contributed to increased or decreased impacts compared to those modeled
in Phase III.
Compared to the prior analysis, the Action Proponents propose to
use more hours of hull-mounted surface ship sonar, and these activities
are newly analyzed in the NOCAL range complex and in PMSR. Compared to
the prior analysis, this analysis considers increased use of MF1
(regular duty cycle) and MF1C (continuous duty cycle) associated with
Navy training activities and decreased use of MF1 and MF1C associated
with Navy testing activities. This analysis also considers the training
and testing usage of these sonars across an expanded study area. For
the maximum analyzed year of training and testing activities under this
proposed action, MF1 has increased 20 percent and MF1C has increased 50
percent in the expanded California Study Area (which now includes PMSR
and NOCAL). In the Hawaii Study Area MF1 and MF1C is proposed to
increase greater than 10 percent and 60 percent respectively when
compared to the prior HSTT analysis.
Additionally, the updated HF cetacean criteria reflect greater
susceptibility to auditory effects at low and mid-frequencies than
previously analyzed. Consequently, the predicted auditory effects due
to sources under 10 kHz, including but not limited to MF1 hull-mounted
sonar and other anti-submarine warfare sonars, are substantially higher
for this auditory group than in prior analyses of the same activities.
Thus, for activities with sonars, some modeled exposures that would
previously have been categorized as significant behavioral responses
may now instead be counted as auditory effects (TTS and AUD INJ).
Similarly, the updated HF cetacean criteria reflect greater
susceptibility to auditory effects at low and mid-frequencies in
impulsive sounds. For VHF cetaceans, susceptibility to auditory effects
has not changed substantially since the prior analysis.

Table 42--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Sonar and Other Active Transducers During Navy Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual Maximum annual Maximum 7-year Maximum 7-year Maximum 7-
Species Stock behavioral TTS AUD INJ behavioral TTS year AUD INJ
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 1,903 2,390 65 12,356 16,019 428
Pacific.
Gray Whale........................ Western North 18 28 1 119 182 2
Pacific.
Blue Whale........................ Central North 10 56 0 63 325 0
Pacific.
Blue Whale........................ Eastern North 646 1,924 16 3,810 9,921 80
Pacific.
Bryde's Whale..................... Eastern Tropical 48 80 1 295 414 1
Pacific.
Bryde's Whale..................... Hawaii.............. 41 263 2 259 1,543 10
Fin Whale......................... Hawaii.............. 12 46 0 73 260 0
Fin Whale......................... California/Oregon/ 1,727 5,470 22 9,743 26,506 108
Washington.
Humpback Whale.................... Central America/ 166 831 13 989 4,076 65
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 375 1,906 31 2,245 9,370 153
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 780 1,358 11 5,134 8,414 70
Minke Whale....................... Hawaii.............. 27 200 2 171 1,154 12
Minke Whale....................... California/Oregon/ 334 1,242 15 2,035 6,234 81
Washington.
Sei Whale......................... Hawaii.............. 25 173 1 162 978 2
Sei Whale......................... Eastern North 38 151 1 223 765 7
Pacific.

[[Page 32236]]

Sperm Whale....................... Hawaii.............. 939 354 0 5,806 2,008 0
Sperm Whale....................... California/Oregon/ 2,133 758 1 11,738 3,677 1
Washington.
Dwarf Sperm Whale................. Hawaii.............. 8,114 27,505 329 53,404 157,962 1,955
Dwarf Sperm Whale................. California/Oregon/ 936 3,346 37 5,472 16,881 188
Washington.
Pygmy Sperm Whale................. Hawaii.............. 8,131 27,918 350 53,462 160,158 2,068
Pygmy Sperm Whale................. California/Oregon/ 964 3,216 43 5,629 16,228 218
Washington.
Baird's Beaked Whale.............. California/Oregon/ 7,234 55 - 39,426 262 -
Washington.
Blainville's Beaked Whale......... Hawaii.............. 5,780 31 - 36,734 180 -
Goose-Beaked Whale................ Hawaii.............. 23,137 118 - 147,104 668 -
Goose-Beaked Whale................ California/Oregon/ 110,330 504 - 635,735 2,514 -
Washington.
Longman's Beaked Whale............ Hawaii.............. 13,966 83 - 89,112 475 -
Mesoplodont Beaked Whale.......... California/Oregon/ 64,298 350 0 369,597 1,732 0
Washington.
False Killer Whale................ Main Hawaiian 68 54 - 436 316 -
Islands Insular.
False Killer Whale................ Northwest Hawaiian 96 55 - 616 343 -
Islands.
False Killer Whale................ Hawaii Pelagic...... 731 638 0 4,647 3,641 0
False Killer Whale................ Baja California 1,361 765 1 7,599 3,949 1
Peninsula Mexico *.
Killer Whale...................... Hawaii.............. 41 62 - 256 354 -
Killer Whale...................... Eastern North 422 110 0 2,682 543 0
Pacific Offshore.
Killer Whale...................... West Coast Transient 19 27 - 87 117 -
Melon-Headed Whale................ Hawaiian Islands.... 12,560 13,553 8 79,341 76,222 48
Melon-Headed Whale................ Kohala Resident 15 8 - 85 45 -
(Hawaii).
Pygmy Killer Whale................ Hawaii.............. 3,666 3,758 1 23,256 21,234 4
Pygmy Killer Whale................ California--Baja 357 118 - 2,103 600 -
California
Peninsula Mexico *.
Short-Finned Pilot Whale.......... Hawaii.............. 8,905 4,931 2 57,475 28,419 11
Short-Finned Pilot Whale.......... California/Oregon/ 1,436 547 1 8,777 2,716 1
Washington.
Bottlenose Dolphin................ Maui Nui............ 186 2 - 1,285 12 -
Bottlenose Dolphin................ Hawaii Island....... 2 3 - 8 16 -
Bottlenose Dolphin................ Hawaii Pelagic...... 32,258 5,040 3 220,679 30,047 20
Bottlenose Dolphin................ Kaua[revaps]i/ 945 233 - 6,098 1,629 -
Ni[revaps]ihau.
Bottlenose Dolphin................ O[revaps]ahu........ 6,672 67 0 46,638 430 0
Bottlenose Dolphin................ California Coastal.. 484 8 - 3,308 51 -
Bottlenose Dolphin................ California/Oregon/ 11,368 5,492 3 65,775 28,363 14
Washington Offshore.
Fraser's Dolphin.................. Hawaii.............. 16,259 14,089 1 103,900 80,236 7
Long-Beaked Common Dolphin........ California.......... 70,884 30,889 20 423,266 156,179 107
Northern Right Whale Dolphin...... California/Oregon/ 15,672 19,635 13 81,148 89,202 60
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 22,095 19,683 14 119,888 89,082 68
Washington.
Pantropical Spotted Dolphin....... Maui Nui............ 811 14 - 5,444 75 -
Pantropical Spotted Dolphin....... Hawaii Island....... 2,086 2,879 2 13,121 16,318 8
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 18,458 17,816 9 118,066 101,178 50
Pantropical Spotted Dolphin....... O[revaps]ahu........ 5,489 97 1 38,207 626 2
Pantropical Spotted Dolphin....... Baja California 48,096 34,318 37 270,474 177,669 189
Peninsula Mexico *.
Risso's Dolphin................... Hawaii.............. 2,781 2,595 1 17,461 14,575 1
Risso's Dolphin................... California/Oregon/ 17,117 7,907 3 99,536 40,443 19
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 45,968 34,070 18 301,367 194,804 102
Short-Beaked Common Dolphin....... California/Oregon/ 876,990 548,702 389 5,081,159 2,770,024 2,023
Washington.
Spinner Dolphin................... Hawaii Pelagic...... 1,679 2,100 1 10,633 11,946 3
Spinner Dolphin................... Hawaii Island....... 46 49 - 273 280 -
Spinner Dolphin................... Kaua[revaps]i/ 2,660 866 1 17,090 6,046 5
Ni[revaps]ihau.
Spinner Dolphin................... O[revaps]ahu/4 971 13 - 6,790 86 -
Islands Region.
Striped Dolphin................... Hawaii Pelagic...... 14,566 16,678 6 92,249 94,018 36
Striped Dolphin................... California/Oregon/ 63,661 46,945 32 359,520 240,671 160
Washington.
Dall's Porpoise................... California/Oregon/ 6,430 36,826 522 37,679 176,737 2,512
Washington.
Harbor Porpoise................... Monterey Bay........ 1,314 0 - 5,627 0 -
Harbor Porpoise................... Morro Bay........... 3,824 46 0 22,754 221 0
Harbor Porpoise................... Northern California/ 357 0 - 1,576 0 -
Southern Oregon.
Harbor Porpoise................... San Francisco/ 6,869 29 0 29,968 127 0
Russian River.
California Sea Lion............... U.S................. 662,716 186,625 115 3,903,717 911,677 653

[[Page 32237]]

Guadalupe Fur Seal................ Mexico.............. 217,808 77,386 32 1,213,525 384,582 162
Northern Fur Seal................. Eastern Pacific..... 19,371 9,876 2 90,896 43,276 9
Northern Fur Seal................. California.......... 13,512 6,134 2 63,833 27,073 8
Steller Sea Lion.................. Eastern............. 389 122 1 1,870 519 1
Harbor Seal....................... California.......... 10,510 1,457 3 61,064 8,093 13
Hawaiian Monk Seal................ Hawaii.............. 590 123 0 4,076 764 0
Northern Elephant Seal............ California Breeding. 28,461 39,790 17 160,245 188,696 82
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1,
that value has been rounded up from a value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year
rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin,
and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were
derived to support the Navy's analysis.

Table 43--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Sonar and Other Active Transducers During Navy Testing Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual Maximum annual Maximum 7-year Maximum 7-year Maximum 7-
Species Stock behavioral TTS AUD INJ behavioral TTS year AUD INJ
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 4,876 6,722 64 28,937 24,742 335
Pacific.
Gray Whale........................ Western North 50 67 1 302 233 3
Pacific.
Blue Whale........................ Central North 5 19 1 27 107 2
Pacific.
Blue Whale........................ Eastern North 696 1,094 8 4,028 5,743 52
Pacific.
Bryde's Whale..................... Eastern Tropical 47 89 2 275 517 8
Pacific.
Bryde's Whale..................... Hawaii.............. 22 75 1 112 412 1
Fin Whale......................... Hawaii.............. 5 19 1 29 114 1
Fin Whale......................... California/Oregon/ 1,741 4,144 21 10,107 19,655 117
Washington.
Humpback Whale.................... Central America/ 343 472 4 2,076 2,269 23
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 818 1,155 8 4,947 5,553 43
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 348 358 4 2,045 2,082 27
Minke Whale....................... Hawaii.............. 12 50 1 64 283 1
Minke Whale....................... California/Oregon/ 563 718 7 3,412 3,555 43
Washington.
Sei Whale......................... Hawaii.............. 11 41 1 57 230 3
Sei Whale......................... Eastern North 37 65 1 215 345 1
Pacific.
Sperm Whale....................... Hawaii.............. 288 56 0 1,452 291 0
Sperm Whale....................... California/Oregon/ 834 129 - 4,350 594 -
Washington.
Dwarf Sperm Whale................. Hawaii.............. 2,189 6,048 371 10,769 31,271 1,805
Dwarf Sperm Whale................. California/Oregon/ 519 709 26 2,796 3,966 149
Washington.
Pygmy Sperm Whale................. Hawaii.............. 2,243 6,137 373 10,987 31,760 1,821
Pygmy Sperm Whale................. California/Oregon/ 525 743 23 2,819 4,116 129
Washington.
Baird's Beaked Whale.............. California/Oregon/ 2,823 5 - 16,049 23 -
Washington.
Blainville's Beaked Whale......... Hawaii.............. 1,702 2 - 8,904 13 -
Goose-Beaked Whale................ Hawaii.............. 6,945 8 - 36,195 44 -
Goose-Beaked Whale................ California/Oregon/ 55,207 92 - 295,610 393 -
Washington.

[[Page 32238]]

Longman's Beaked Whale............ Hawaii.............. 4,106 12 - 21,483 61 -
Mesoplodont Beaked Whale.......... California/Oregon/ 27,697 62 - 146,347 259 -
Washington.
False Killer Whale................ Main Hawaiian 32 9 - 171 53 -
Islands Insular.
False Killer Whale................ Northwest Hawaiian 30 8 - 150 47 -
Islands.
False Killer Whale................ Hawaii Pelagic...... 192 95 1 987 502 1
False Killer Whale................ Baja California 332 60 0 1,831 392 0
Peninsula Mexico *.
Killer Whale...................... Hawaii.............. 14 8 - 71 42 -
Killer Whale...................... Eastern North 399 75 0 2,318 440 0
Pacific Offshore.
Killer Whale...................... West Coast Transient 7 1 - 45 7 -
Melon-Headed Whale................ Hawaiian Islands.... 3,396 1,711 2 17,285 9,306 13
Melon-Headed Whale................ Kohala Resident 25 6 - 161 34 -
(Hawaii).
Pygmy Killer Whale................ Hawaii.............. 928 481 1 4,641 2,510 1
Pygmy Killer Whale................ California--Baja 260 53 - 1,376 257 -
California
Peninsula Mexico *.
Short-Finned Pilot Whale.......... Hawaii.............. 2,625 734 1 14,186 3,955 2
Short-Finned Pilot Whale.......... California/Oregon/ 1,899 371 1 10,796 2,075 1
Washington.
Bottlenose Dolphin................ Maui Nui............ 121 12 0 751 72 0
Bottlenose Dolphin................ Hawaii Island....... 3 - - 19 - -
Bottlenose Dolphin................ Hawaii Pelagic...... 4,805 842 1 28,873 4,998 7
Bottlenose Dolphin................ Kaua[revaps]i/ 276 5 - 1,559 27 -
Ni[revaps]ihau.
Bottlenose Dolphin................ O[revaps]ahu........ 407 35 1 2,727 237 1
Bottlenose Dolphin................ California Coastal.. 811 20 - 5,123 103 -
Bottlenose Dolphin................ California/Oregon/ 9,699 1,286 1 55,144 6,926 3
Washington Offshore.
Fraser's Dolphin.................. Hawaii.............. 3,562 1,524 1 18,148 7,963 2
Long-Beaked Common Dolphin........ California.......... 181,795 11,646 6 1,156,935 57,311 31
Northern Right Whale Dolphin...... California/Oregon/ 7,934 1,997 2 43,020 8,762 9
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 23,127 3,851 2 132,034 17,006 13
Washington.
Pantropical Spotted Dolphin....... Maui Nui............ 1,358 157 1 8,514 943 1
Pantropical Spotted Dolphin....... Hawaii Island....... 789 234 1 4,524 1,389 1
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 5,521 2,324 2 28,528 12,527 9
Pantropical Spotted Dolphin....... O[revaps]ahu........ 748 58 1 4,749 392 2
Pantropical Spotted Dolphin....... Baja California 12,181 2,468 2 67,222 16,411 10
Peninsula Mexico *.
Risso's Dolphin................... Hawaii.............. 745 396 1 3,652 2,091 2
Risso's Dolphin................... California/Oregon/ 15,852 2,686 1 86,994 12,028 5
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 11,455 4,768 3 62,028 25,394 15
Short-Beaked Common Dolphin....... California/Oregon/ 611,376 119,400 58 3,312,917 550,748 324
Washington.
Spinner Dolphin................... Hawaii Pelagic...... 473 265 1 2,345 1,445 1
Spinner Dolphin................... Hawaii Island....... 13 0 - 82 0 -
Spinner Dolphin................... Kaua[revaps]i/ 901 16 - 5,096 90 -
Ni[revaps]ihau.
Spinner Dolphin................... O[revaps]ahu/4 180 28 0 1,120 155 0
Islands Region.
Striped Dolphin................... Hawaii Pelagic...... 3,793 2,473 1 18,660 12,807 6
Striped Dolphin................... California/Oregon/ 16,581 5,362 2 88,084 29,998 12
Washington.

[[Page 32239]]

Dall's Porpoise................... California/Oregon/ 6,191 8,086 222 34,212 43,404 1,300
Washington.
Harbor Porpoise................... Monterey Bay........ 865 - - 5,307 - -
Harbor Porpoise................... Morro Bay........... 254 3 1 1,660 19 1
Harbor Porpoise................... Northern California/ 124 - - 763 - -
Southern Oregon.
Harbor Porpoise................... San Francisco/ 3,023 6 0 18,554 36 0
Russian River.
California Sea Lion............... U.S................. 928,540 67,321 16 5,191,344 245,578 71
Guadalupe Fur Seal................ Mexico.............. 44,414 3,814 3 249,924 24,054 21
Northern Fur Seal................. Eastern Pacific..... 3,080 183 1 18,776 1,111 1
Northern Fur Seal................. California.......... 1,769 87 0 10,740 521 0
Steller Sea Lion.................. Eastern............. 439 31 - 2,678 174 -
Harbor Seal....................... California.......... 38,391 15,461 3 204,018 81,833 14
Hawaiian Monk Seal................ Hawaii.............. 75 43 1 406 257 1
Northern Elephant Seal............ California Breeding. 34,434 13,065 5 203,952 54,851 27
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1,
that value has been rounded up from a value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year
rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin,
and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were
derived to support the Navy's analysis.

Table 44--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Sonar and Other Active Transducers During Coast Guard Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual Maximum annual Maximum 7-year Maximum 7-year Maximum 7-year
Species Stock behavioral TTS AUD INJ behavioral TTS AUD INJ
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 15 - - 102 - -
Pacific.
Gray Whale........................ Western North 1 - - 2 - -
Pacific.
Blue Whale........................ Central North 1 - - 1 - -
Pacific.
Blue Whale........................ Eastern North 18 - - 124 - -
Pacific.
Bryde's Whale..................... Eastern Tropical 1 - - 5 - -
Pacific.
Bryde's Whale..................... Hawaii.............. 2 - - 13 - -
Fin Whale......................... Hawaii.............. 2 - - 8 - -
Fin Whale......................... California/Oregon/ 62 - - 432 - -
Washington.
Humpback Whale.................... Central America/ 7 - - 45 - -
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 14 - - 96 - -
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 7 - - 46 - -
Minke Whale....................... Hawaii.............. 2 - - 14 - -
Minke Whale....................... California/Oregon/ 7 - - 48 - -
Washington.
Sei Whale......................... Hawaii.............. 1 - - 4 - -
Sei Whale......................... Eastern North 1 - - 4 - -
Pacific.
Sperm Whale....................... Hawaii.............. 7 - - 45 - -
Sperm Whale....................... California/Oregon/ 28 - - 196 - -
Washington.
Dwarf Sperm Whale................. Hawaii.............. 159 225 2 1,109 1,575 12
Dwarf Sperm Whale................. California/Oregon/ 16 34 - 108 235 -
Washington.
Pygmy Sperm Whale................. Hawaii.............. 160 192 - 1,117 1,342 -
Pygmy Sperm Whale................. California/Oregon/ 17 31 - 116 215 -
Washington.
Baird's Beaked Whale.............. California/Oregon/ 54 - - 378 - -
Washington.
Blainville's Beaked Whale......... Hawaii.............. 25 - - 170 - -
Goose-Beaked Whale................ Hawaii.............. 143 - - 1,001 - -
Goose-Beaked Whale................ California/Oregon/ 653 - - 4,569 - -
Washington.
Longman's Beaked Whale............ Hawaii.............. 145 - - 1,013 - -
Mesoplodont Beaked Whale.......... California/Oregon/ 415 - - 2,901 - -
Washington.
False Killer Whale................ Main Hawaiian 4 - - 27 - -
Islands Insular.

[[Page 32240]]

False Killer Whale................ Northwest Hawaiian 2 - - 9 - -
Islands.
False Killer Whale................ Hawaii Pelagic...... 12 - - 83 - -
False Killer Whale................ Baja California 16 - - 109 - -
Peninsula Mexico *.
Killer Whale...................... Hawaii.............. 2 - - 10 - -
Killer Whale...................... Eastern North 1 - - 7 - -
Pacific Offshore.
Killer Whale...................... West Coast Transient 1 - - 5 - -
Melon-Headed Whale................ Hawaiian Islands.... 223 - - 1,558 - -
Pygmy Killer Whale................ Hawaii.............. 56 - - 390 - -
Pygmy Killer Whale................ California--Baja 3 - - 18 - -
California
Peninsula Mexico *.
Short-Finned Pilot Whale.......... Hawaii.............. 83 - - 578 - -
Short-Finned Pilot Whale.......... California/Oregon/ 10 - - 69 - -
Washington.
Bottlenose Dolphin................ Hawaii Pelagic...... 33 - - 226 - -
Bottlenose Dolphin................ California Coastal.. 2 - - 12 - -
Bottlenose Dolphin................ California/Oregon/ 119 - - 828 - -
Washington Offshore.
Fraser's Dolphin.................. Hawaii.............. 17 - - 113 - -
Long-Beaked Common Dolphin........ California.......... 924 1 - 6,467 6 -
Northern Right Whale Dolphin...... California/Oregon/ 249 2 - 1,742 12 -
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 246 1 - 1,722 7 -
Washington.
Pantropical Spotted Dolphin....... Hawaii Island....... 24 - - 164 - -
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 226 - - 1,579 - -
Pantropical Spotted Dolphin....... O[revaps]ahu........ 1 - - 7 - -
Pantropical Spotted Dolphin....... Baja California 490 - - 3,428 - -
Peninsula Mexico *.
Risso's Dolphin................... Hawaii.............. 35 - - 240 - -
Risso's Dolphin................... California/Oregon/ 187 - - 1,308 - -
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 406 - - 2,838 - -
Short-Beaked Common Dolphin....... California/Oregon/ 9,634 19 - 67,436 131 -
Washington.
Spinner Dolphin................... Hawaii Pelagic...... 24 - - 165 - -
Striped Dolphin................... Hawaii Pelagic...... 247 2 - 1,726 12 -
Striped Dolphin................... California/Oregon/ 775 - - 5,419 - -
Washington.
Dall's Porpoise................... California/Oregon/ 169 239 - 1,178 1,669 -
Washington.
Harbor Porpoise................... San Francisco/ 2 - - 11 - -
Russian River.
California Sea Lion............... U.S................. 14,931 2 - 104,514 13 -
Guadalupe Fur Seal................ Mexico.............. 3,852 4 - 26,963 24 -
Northern Fur Seal................. Eastern Pacific..... 633 - - 4,425 - -
Northern Fur Seal................. California.......... 555 - - 3,885 - -
Steller Sea Lion.................. Eastern............. 4 - - 22 - -
Harbor Seal....................... California.......... 140 - - 976 - -
Hawaiian Monk Seal................ Hawaii.............. 1 - - 5 - -
Northern Elephant Seal............ California Breeding. 1,790 1 - 12,529 1 -
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1,
that value has been rounded up from a value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year
rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin,
and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were
derived to support the Navy's analysis.

Estimated Take From Air Guns and Pile Driving
Table 45 provides estimated effects from air guns, including the
comparative amounts of TTS and behavioral disturbance for each species
and stock annually, noting that if a modeled marine mammal was
``taken'' through exposure to both TTS and behavioral disturbance in
the model, it was recorded as a TTS.

Table 45--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Air Guns During Navy Training and Testing Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum annual Maximum annual Maximum annual Maximum 7-year Maximum 7-year Maximum 7-year
Species Stock behavioral TTS AUD INJ behavioral TTS AUD INJ
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North 0 - - 0 - -
Pacific.
Blue Whale........................ Eastern North 0 - - 0 - -
Pacific.

[[Page 32241]]

Fin Whale......................... California/Oregon/ 0 0 - 0 0 -
Washington.
Humpback Whale.................... Central America/ 0 - - 0 - -
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale.................... Mainland Mexico-- 0 0 - 0 0 -
California/Oregon/
Washington.
Humpback Whale.................... Hawaii.............. 1 - - 1 - -
Minke Whale....................... California/Oregon/ 0 - - 0 - -
Washington.
Sperm Whale....................... Hawaii.............. 1 - - 1 - -
Dwarf Sperm Whale................. Hawaii.............. 8 5 1 50 34 1
Dwarf Sperm Whale................. California/Oregon/ 1 1 - 4 3 -
Washington.
Pygmy Sperm Whale................. Hawaii.............. 6 6 1 34 37 3
Pygmy Sperm Whale................. California/Oregon/ 1 1 - 3 6 -
Washington.
Goose-Beaked Whale................ Hawaii.............. 1 - - 1 - -
Mesoplodont Beaked Whale.......... California/Oregon/ 0 - - 0 - -
Washington.
Melon-Headed Whale................ Hawaiian Islands.... 1 - - 2 - -
Pygmy Killer Whale................ California--Baja 1 - - 1 - -
California
Peninsula Mexico.
Short-Finned Pilot Whale.......... Hawaii.............. 1 - - 1 - -
Bottlenose Dolphin................ Hawaii Pelagic...... 1 - - 3 - -
Bottlenose Dolphin................ California/Oregon/ 1 - - 2 - -
Washington Offshore.
Long-Beaked Common Dolphin........ California.......... 3 - - 13 - -
Northern Right Whale Dolphin...... California/Oregon/ 1 - - 2 - -
Washington.
Pacific White-Sided Dolphin....... California/Oregon/ 1 - - 5 - -
Washington.
Pantropical Spotted Dolphin....... Hawaii Island....... 1 - - 1 - -
Pantropical Spotted Dolphin....... Hawaii Pelagic...... 1 - - 1 - -
Pantropical Spotted Dolphin....... Baja California 2 - - 9 - -
Peninsula Mexico.
Risso's Dolphin................... California/Oregon/ 1 - - 6 - -
Washington.
Rough-Toothed Dolphin............. Hawaii.............. 1 - - 1 - -
Short-Beaked Common Dolphin....... California/Oregon/ 17 - - 85 - -
Washington.
Striped Dolphin................... Hawaii Pelagic...... - 1 - - 1 -
Striped Dolphin................... California/Oregon/ 1 - - 5 - -
Washington.
Dall's Porpoise................... California/Oregon/ 9 8 1 58 48 4
Washington.
Harbor Porpoise................... San Francisco/ 1 2 1 6 12 1
Russian River.
California Sea Lion............... U.S................. 8 1 - 33 1 -
Guadalupe Fur Seal................ Mexico.............. 1 - - 5 - -
Northern Fur Seal................. Eastern Pacific..... 1 - - 2 - -
Northern Fur Seal................. California.......... 1 - - 1 - -
Northern Elephant Seal............ California Breeding. 1 - - 3 - -
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1,
that value has been rounded up from a value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year
rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic Analysis Report) of the 2024 HCTT Draft EIS/OEIS.

Table 46 provides the estimated effects from pile driving and
extraction, including the comparative amounts of TTS and behavioral
disturbance for each species and stock annually, noting that if a
modeled marine mammal was ``taken'' through exposure to both TTS and
behavioral disturbance in the model, it was recorded as a TTS.

Table 46--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Pile Driving During Navy Training Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum 7-
Species Stock Maximum annual Maximum annual Maximum annual year Maximum 7- Maximum 7-
behavioral TTS AUD INJ behavioral year TTS year AUD INJ
--------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion............... U.S................. 16,992 1,891 61 118,938 13,237 423
Harbor Seal....................... California.......... 952 183 20 6,664 1,281 138
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 32242]]

Estimated Take From Target and Missile Launch Activities
Table 47 provides the estimated effects from target and missile
launch activities at SNI and PMRF, including the amounts of behavioral
disturbance for each species and stock annually. Pinnipeds hauled out
on the shoreline of SNI have been observed to behaviorally react to the
sound of launches of targets and missiles from launch pads on the
island (Naval Air Warfare Center Weapons Division, 2018; U.S.
Department of the Navy, 2020b, 2022b, 2023). The estimate of the number
of behavioral effects that would be expected due to in-air noise from
launches was based on observations of pinnipeds over three monitoring
seasons (2015-2017) divided by the number of launch events over that
same time period. The Navy determined that the numbers presented in
table 46 (see table 5-6 of the application) represent the number of
pinnipeds expected to be hauled out at SNI based on surveys over the
five-year period from 2014 to 2019 (U.S. Department of the Navy, 2020a)
and the average number of effects observed per launch event (U.S.
Department of the Navy, 2020b, 2022b, 2023). Of note, the estimated
behavioral effects presented in table 47 are the same as those
authorized in the July 2022 PMSR LOA (87 FR 40888, July 8, 2022).
For California sea lions, take estimates at SNI were derived from
three monitoring seasons (2015 to 2017) where an average of 274.44
instances of take of sea lions by Level B harassment occurred per
launch event. Therefore, 275 sea lions was multiplied by 40 launch
events, for a take estimate of 11,000 instances of take by Level B
harassment of California sea lions annually (table 47). Of note, the
Navy has not conducted more than 25 launch events in a given year since
2001. For harbor seals, a total of 12 takes were derived from the 2016
and 2017 monitoring seasons and multiplied by 40 launch events for a
total of 480 instances of take by Level B harassment annually (table
47). For northern elephant seals, take estimates were derived from
three monitoring seasons (2015 to 2017) where an average of 0.61
instances of take of northern elephant seals by Level B harassment
occurred per launch event. Therefore, one northern elephant seal was
multiplied by 40 launch events for a take estimate of 40 instances of
take by Level B harassment of northern elephant seals annually (table
47). Generally, northern elephant seals do not react to launch events
other than simple alerting responses such as raising their heads or
temporarily going from sleeping to being awake; however, to account for
the rare instances where they have reacted, the Navy considered that
some northern elephant seals could be taken during launch events.
At PMRF from 2020 to 2023, an annual average of 215 monk seals have
been counted hauled out on the beach (unpublished Navy data). The
maximum number of seals observed during a single observation was five
and the minimum was zero; on most observations no hauled out seals were
observed. Based on the annual average number of animals documented at
the site, the Action Proponents estimate that weapons firing noise at
PMRF would result in 215 behavioral effects annually on hauled out monk
seals (table 47; see table 5-7 of the application). The analysis
conservatively assumes that: (1) at least one monk seal is hauled out
when a launch or firing event would occur, an assumption contradicted
by the observational data, which indicates that most frequently no monk
seals are hauled out on the beach; and (2) that a monk seal would be
disturbed and behaviorally respond during each event. This estimate is
well beyond the anticipated take due to the 35 missile, rocket, drone
launches and 3 artillery events (38 total) events on average per year.
Monk seal in-air hearing is less sensitive than hearing in other phocid
seals (Ruscher et al., 2021; Ruscher et al., 2025), suggesting that
monk seals may be less likely to respond to in-air noise.
Neither TTS nor auditory injury is anticipated from missile and
launch activities, as marine mammals are not anticipated to be exposed
to noise from these activities that exceed the TTS or auditory injury
thresholds (see the 2024 HCTT Draft EIS/OEIS appendix E.1, In-Air
Acoustic Effects on Pinnipeds from Weapons Firing Noise).

Table 47--Annual and 7-Year Estimated Take of Marine Mammal Stocks From In-Air Acoustic Stressors From Missile,
Aerial Target, and Air Vehicle Launches and Artillery Firing
----------------------------------------------------------------------------------------------------------------
Maximum Maximum 7-
Species Stock annual year
behavioral behavioral
----------------------------------------------------------------------------------------------------------------
California sea lion........................... U.S............................. 11,000 77,000
Harbor seal................................... California...................... 480 3,360
Hawaiian monk seal............................ Hawai[revaps]i.................. 215 1,505
Northern elephant seal........................ California...................... 40 280
----------------------------------------------------------------------------------------------------------------
Note: California sea lion, harbor seal, and northern elephant seal are expected at San Nicolas Island only.
Hawaiian monk seal is expected at the Pacific Missile Range Facility only.

Estimated Take From Explosives
Table 48 provides estimated effects from explosives during Navy
training activities and table 49 provides estimated effects from
explosives including small ship shock trials from Navy testing
activities. Table 50 provides estimated effects from small ship shock
trials over a maximum year (i.e., one event) of Navy testing
activities, which is a subset of the information included in table 49.
Table 51 provides estimated effects from explosives during Coast Guard
training activities, and table 52 provides estimated effects from
explosives during Army training activities.

[[Page 32243]]

Table 48--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Explosives During Navy Training Activities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
Maximum Maximum Maximum annual Maximum Maximum 7- Maximum 7- Maximum 7- Maximum 7-
Species Stock annual annual annual non- annual year Maximum 7- year AUD year non- year
behavioral TTS AUD INJ auditory mortality behavioral year TTS INJ auditory mortality
injury injury
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale................................ Eastern North Pacific....... 234 391 33 0 .......... 1,491 2,578 217 0 ..........
Gray Whale................................ Western North Pacific....... 1 1 0 .......... .......... 2 2 0 .......... ..........
Blue Whale................................ Central North Pacific....... 1 .......... .......... .......... .......... 1 .......... .......... .......... ..........
Blue Whale................................ Eastern North Pacific....... 65 81 1 .......... .......... 415 535 4 .......... ..........
Bryde's Whale............................. Eastern Tropical Pacific.... 12 39 1 .......... .......... 73 259 4 .......... ..........
Bryde's Whale............................. Hawaii...................... 1 1 0 .......... .......... 5 2 0 .......... ..........
Fin Whale................................. Hawaii...................... 1 0 0 .......... .......... 1 0 0 .......... ..........
Fin Whale................................. California/Oregon/Washington 98 114 5 1 .......... 633 747 35 1 ..........
Humpback Whale............................ Central America/Southern 18 27 1 .......... .......... 115 181 3 .......... ..........
Mexico--California/Oregon/
Washington.
Humpback Whale............................ Mainland Mexico--California/ 35 85 3 .......... .......... 225 574 18 .......... ..........
Oregon/Washington.
Humpback Whale............................ Hawaii...................... 48 58 7 .......... .......... 312 390 43 .......... ..........
Minke Whale............................... Hawaii...................... 1 1 .......... .......... .......... 4 1 .......... .......... ..........
Minke Whale............................... California/Oregon/Washington 29 81 9 .......... .......... 182 529 63 .......... ..........
Sei Whale................................. Hawaii...................... 1 1 0 .......... .......... 4 2 0 .......... ..........
Sei Whale................................. Eastern North Pacific....... 5 1 0 .......... .......... 34 6 0 .......... ..........
Sperm Whale............................... Hawaii...................... 2 1 1 .......... .......... 9 6 1 .......... ..........
Sperm Whale............................... California/Oregon/Washington 2 4 1 .......... .......... 8 24 3 .......... ..........
Dwarf Sperm Whale......................... Hawaii...................... 272 407 171 1 0 1,692 2,630 1,109 1 0
Dwarf Sperm Whale......................... California/Oregon/Washington 12 35 13 .......... .......... 75 219 83 .......... ..........
Pygmy Sperm Whale......................... Hawaii...................... 259 414 167 1 0 1,617 2,711 1,084 1 0
Pygmy Sperm Whale......................... California/Oregon/Washington 19 41 23 0 .......... 117 272 153 0 ..........
Baird's Beaked Whale...................... California/Oregon/Washington .......... 1 .......... .......... .......... .......... 4 .......... .......... ..........
Blainville's Beaked Whale................. Hawaii...................... 1 .......... .......... .......... .......... 2 .......... .......... .......... ..........
Goose-Beaked Whale........................ Hawaii...................... 2 1 0 .......... .......... 11 4 0 .......... ..........
Goose-Beaked Whale........................ California/Oregon/Washington 6 13 1 .......... .......... 36 89 2 .......... ..........
Longman's Beaked Whale.................... Hawaii...................... 1 1 1 .......... .......... 2 3 4 .......... ..........
Mesoplodont Beaked Whale.................. California/Oregon/Washington 2 5 1 .......... .......... 11 34 2 .......... ..........
False Killer Whale........................ Main Hawaiian Islands .......... 0 .......... .......... .......... .......... 0 .......... .......... ..........
Insular.
False Killer Whale........................ Hawaii Pelagic.............. 1 1 .......... .......... .......... 2 3 .......... .......... ..........
False Killer Whale........................ Baja California Peninsula 0 1 .......... .......... .......... 0 4 .......... .......... ..........
Mexico.
Killer Whale.............................. Hawaii...................... .......... 0 0 .......... .......... .......... 0 0 .......... ..........
Killer Whale.............................. Eastern North Pacific 6 7 3 .......... .......... 38 47 21 .......... ..........
Offshore.
Melon-Headed Whale........................ Hawaiian Islands............ 4 3 1 0 0 24 20 5 0 0
Pygmy Killer Whale........................ Hawaii...................... 2 2 1 0 .......... 11 13 3 0 ..........
Pygmy Killer Whale........................ California--Baja California 1 1 .......... .......... .......... 1 1 .......... .......... ..........
Peninsula Mexico.
Short-Finned Pilot Whale.................. Hawaii...................... 6 9 1 0 0 40 57 7 0 0
Short-Finned Pilot Whale.................. California/Oregon/Washington 6 6 6 2 1 35 39 41 12 4
Bottlenose Dolphin........................ Maui Nui.................... 0 1 .......... .......... .......... 0 4 .......... .......... ..........
Bottlenose Dolphin........................ Hawaii Island............... 0 1 .......... .......... .......... 0 1 .......... .......... ..........
Bottlenose Dolphin........................ Hawaii Pelagic.............. 134 114 14 1 1 920 783 96 7 2
Bottlenose Dolphin........................ Kaua[revaps]i/Ni[revaps]ihau .......... 1 0 0 .......... .......... 1 0 0 ..........
Bottlenose Dolphin........................ O[revaps]ahu................ 29 21 4 1 1 200 142 26 3 1
Bottlenose Dolphin........................ California Coastal.......... 9 15 6 1 .......... 59 103 41 1 ..........
Bottlenose Dolphin........................ California/Oregon/Washington 38 40 9 1 0 240 260 57 3 0
Offshore.
Fraser's Dolphin.......................... Hawaii...................... 13 10 3 1 .......... 74 64 18 1 ..........
Long-Beaked Common Dolphin................ California.................. 273 306 75 18 3 1,641 1,976 498 117 15
Northern Right Whale Dolphin.............. California/Oregon/Washington 2 4 1 1 0 13 24 1 3 0
Pacific White-Sided Dolphin............... California/Oregon/Washington 77 73 16 3 1 463 470 101 19 1
Pantropical Spotted Dolphin............... Maui Nui.................... 3 2 2 0 .......... 18 12 10 0 ..........
Pantropical Spotted Dolphin............... Hawaii Island............... 1 8 2 1 .......... 7 55 13 2 ..........
Pantropical Spotted Dolphin............... Hawaii Pelagic.............. 11 13 3 1 0 69 87 15 2 0
Pantropical Spotted Dolphin............... O[revaps]ahu................ 17 15 3 1 .......... 118 100 18 1 ..........
Pantropical Spotted Dolphin............... Baja California Peninsula 15 11 5 1 1 93 75 29 6 1
Mexico.
Risso's Dolphin........................... Hawaii...................... 2 2 0 0 .......... 9 9 0 0 ..........

[[Page 32244]]

Risso's Dolphin........................... California/Oregon/Washington 23 38 9 3 .......... 146 252 62 17 ..........
Rough-Toothed Dolphin..................... Hawaii...................... 72 63 6 3 1 481 426 38 17 1
Short-Beaked Common Dolphin............... California/Oregon/Washington 1,413 1,078 255 50 13 8,979 6,965 1,684 329 91
Spinner Dolphin........................... Hawaii Pelagic.............. 1 1 0 0 .......... 2 2 0 0 ..........
Spinner Dolphin........................... Hawaii Island............... 1 1 1 0 .......... 7 2 1 0 ..........
Spinner Dolphin........................... Kaua[revaps]i/Ni[revaps]ihau 0 2 0 0 0 0 11 0 0 0
Spinner Dolphin........................... O'ahu/4 Islands Region...... 4 3 1 0 0 27 19 2 0 0
Striped Dolphin........................... Hawaii Pelagic.............. 11 5 1 1 .......... 59 31 4 3 ..........
Striped Dolphin........................... California/Oregon/Washington 12 23 4 1 1 73 148 27 6 1
Dall's Porpoise........................... California/Oregon/Washington 155 433 185 1 .......... 975 2,787 1,214 1 ..........
Harbor Porpoise........................... Morro Bay................... .......... 13 11 0 .......... .......... 76 71 0 ..........
Harbor Porpoise........................... San Francisco/Russian River. .......... 22 24 .......... .......... .......... 153 164 .......... ..........
California Sea Lion....................... U.S......................... 3,254 4,576 313 43 4 20,202 29,753 2,048 282 22
Guadalupe Fur Seal........................ Mexico...................... 50 60 4 1 1 312 361 25 7 1
Northern Fur Seal......................... Eastern Pacific............. 1 2 1 0 .......... 1 14 1 0 ..........
Northern Fur Seal......................... California.................. 1 2 1 0 .......... 1 11 1 0 ..........
Steller Sea Lion.......................... Eastern..................... 5 8 2 .......... .......... 31 50 12 .......... ..........
Harbor Seal............................... California.................. 1,510 2,050 214 6 1 9,224 12,668 1,343 42 7
Hawaiian Monk Seal........................ Hawaii...................... 14 21 3 1 0 89 136 17 1 0
Northern Elephant Seal.................... California Breeding......... 147 229 31 1 .......... 936 1,505 201 1 ..........
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin, and pygmy killer whales are not
recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were derived to support the Navy's analysis.

Table 49--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Explosives During Navy Testing Activities (Includes Small Ship Shock Trials)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Maximum 7-
Maximum Maximum Maximum annual non- Maximum Maximum 7- Maximum Maximum year non- Maximum
Species Stock annual annual TTS annual AUD auditory annual year 7-year 7-year auditory 7-year
behavioral INJ injury mortality behavioral TTS AUD INJ injury mortality
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale.............................. Eastern North Pacific..... 123 56 5 0 - 713 353 30 0 -
Gray Whale.............................. Western North Pacific..... 2 1 0 - - 9 1 0 - -
Blue Whale.............................. Eastern North Pacific..... 21 25 2 - - 135 96 14 - -
Bryde's Whale........................... Eastern Tropical Pacific.. 3 3 1 - - 16 20 1 - -
Bryde's Whale........................... Hawaii.................... 1 1 0 - - 1 6 0 - -
Fin Whale............................... Hawaii.................... 1 0 - - - 2 0 - - -
Fin Whale............................... California/Oregon/ 76 69 6 0 - 451 284 39 0 -
Washington.
Humpback Whale.......................... Central America/Southern 13 11 1 - - 80 67 5 - -
Mexico--California/Oregon/
Washington.
Humpback Whale.......................... Mainland Mexico-- 31 29 1 1 - 187 172 5 1 -
California/Oregon/
Washington.
Humpback Whale.......................... Hawaii.................... 40 32 2 - - 275 224 11 - -
Minke Whale............................. Hawaii.................... 1 1 0 - - 3 1 0 - -
Minke Whale............................. California/Oregon/ 9 10 1 - 0 58 63 6 - 0
Washington.
Sei Whale............................... Hawaii.................... 0 0 - - - 0 0 - - -
Sei Whale............................... Eastern North Pacific..... 2 2 1 - - 11 8 1 - -
Sperm Whale............................. Hawaii.................... 0 1 - - - 0 1 - - -
Sperm Whale............................. California/Oregon/ 2 1 1 - - 12 7 1 - -
Washington.
Dwarf Sperm Whale....................... Hawaii.................... 86 107 27 0 0 548 669 135 0 0
Dwarf Sperm Whale....................... California/Oregon/ 20 33 17 - 0 127 205 96 - 0
Washington.
Pygmy Sperm Whale....................... Hawaii.................... 97 114 28 0 - 614 718 142 0 -
Pygmy Sperm Whale....................... California/Oregon/ 22 33 18 - - 145 200 109 - -
Washington.
Baird's Beaked Whale.................... California/Oregon/ 1 1 0 - - 5 2 0 - -
Washington.
Blainville's Beaked Whale............... Hawaii.................... 0 - - - - 0 - - - -
Goose-Beaked Whale...................... Hawaii.................... 1 1 0 - - 4 1 0 - -
Goose-Beaked Whale...................... California/Oregon/ 8 3 1 0 - 50 16 2 0 -
Washington.

[[Page 32245]]

Longman's Beaked Whale.................. Hawaii.................... 0 0 - - - 0 0 - - -
Mesoplodont Beaked Whale................ California/Oregon/ 6 3 1 0 0 35 21 4 0 0
Washington.
False Killer Whale...................... Main Hawaiian Islands 1 1 - - - 3 3 - - -
Insular.
False Killer Whale...................... Hawaii Pelagic............ 0 0 0 - - 0 0 0 - -
False Killer Whale...................... Baja California Peninsula 0 1 0 0 - 0 3 0 0 -
Mexico *.
Killer Whale............................ Eastern North Pacific 2 1 1 0 - 8 6 2 0 -
Offshore.
Melon-Headed Whale...................... Hawaiian Islands.......... 1 1 1 0 - 4 2 1 0 -
Pygmy Killer Whale...................... Hawaii.................... 1 0 0 0 - 1 0 0 0 -
Pygmy Killer Whale...................... California--Baja - 1 0 0 - - 1 0 0 -
California Peninsula
Mexico *.
Short-Finned Pilot Whale................ Hawaii.................... 4 3 1 - - 26 20 3 - -
Short-Finned Pilot Whale................ California/Oregon/ 2 2 1 - - 14 11 1 - -
Washington.
Bottlenose Dolphin...................... Maui Nui.................. 2 2 - - - 13 14 - - -
Bottlenose Dolphin...................... Hawaii Pelagic............ 51 32 4 1 - 354 222 27 5 -
Bottlenose Dolphin...................... Kaua[revaps]i/ 0 0 0 - - 0 0 0 - -
Ni[revaps]ihau.
Bottlenose Dolphin...................... O'ahu..................... - 1 0 0 - - 1 0 0 -
Bottlenose Dolphin...................... California Coastal........ - 1 0 0 - - 2 0 0 -
Bottlenose Dolphin...................... California/Oregon/ 6 7 1 0 - 40 48 6 0 -
Washington Offshore.
Fraser's Dolphin........................ Hawaii.................... 0 0 0 - - 0 0 0 - -
Long-Beaked Common Dolphin.............. California................ 72 83 27 6 1 472 525 168 31 2
Northern Right Whale Dolphin............ California/Oregon/ 9 9 3 1 1 59 55 20 3 1
Washington.
Pacific White-Sided Dolphin............. California/Oregon/ 25 31 6 1 1 168 204 36 5 1
Washington.
Pantropical Spotted Dolphin............. Maui Nui.................. 19 8 1 0 - 131 54 7 0 -
Pantropical Spotted Dolphin............. Hawaii Island............. 1 1 1 - - 3 2 1 - -
Pantropical Spotted Dolphin............. Hawaii Pelagic............ 12 4 1 1 0 78 27 2 1 0
Pantropical Spotted Dolphin............. O[revaps]ahu.............. - 1 0 - - - 1 0 - -
Pantropical Spotted Dolphin............. Baja California Peninsula 25 19 1 1 1 171 128 4 1 1
Mexico *.
Risso's Dolphin......................... Hawaii.................... 1 1 1 - - 2 1 1 - -
Risso's Dolphin......................... California/Oregon/ 11 10 4 1 0 71 62 21 1 0
Washington.
Rough-Toothed Dolphin................... Hawaii.................... 42 23 3 1 1 289 160 19 3 1
Short-Beaked Common Dolphin............. California/Oregon/ 428 492 103 21 5 2,819 3,129 601 112 16
Washington.
Spinner Dolphin......................... Hawaii Pelagic............ 0 1 0 0 - 0 1 0 0 -
Spinner Dolphin......................... Hawaii Island............. 0 - - - - 0 - - - -
Spinner Dolphin......................... Kaua[revaps]i/ 0 1 1 - - 0 1 1 - -
Ni[revaps]ihau.
Spinner Dolphin......................... O[revaps]ahu/4 Islands 1 1 - - - 5 3 - - -
Region.
Striped Dolphin......................... Hawaii Pelagic............ 2 1 1 0 - 9 5 1 0 -
Striped Dolphin......................... California/Oregon/ 16 22 4 1 0 108 147 23 3 0
Washington.
Dall's Porpoise......................... California/Oregon/ 438 631 304 1 0 2,808 3,857 1,748 4 0
Washington.
Harbor Porpoise......................... Monterey Bay.............. 0 - - - - 0 - - - -
Harbor Porpoise......................... Morro Bay................. 74 159 75 1 0 495 1,091 516 2 0
Harbor Porpoise......................... San Francisco/Russian 3 3 1 - - 15 18 4 - -
River.
California Sea Lion..................... U.S....................... 842 1,046 161 14 1 5,409 6,705 1,008 87 5
Guadalupe Fur Seal...................... Mexico.................... 73 90 12 2 0 483 599 76 9 0
Northern Fur Seal....................... Eastern Pacific........... 19 28 7 1 0 117 177 42 2 0
Northern Fur Seal....................... California................ 15 22 6 1 0 93 140 35 3 0
Steller Sea Lion........................ Eastern................... 0 1 0 - - 0 2 0 - -
Harbor Seal............................. California................ 170 158 14 1 0 1,030 977 90 2 0
Hawaiian Monk Seal...................... Hawaii.................... 10 11 1 - - 65 74 6 - -
Northern Elephant Seal.................. California Breeding....... 220 332 55 1 0 1,427 2,096 332 1 0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1, that value has been rounded up from a
value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic
Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin, and pygmy killer whales are not
recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were derived to support the Navy's analysis.

[[Page 32246]]

Table 50--Annual Estimated Take of Marine Mammal Stocks From Small Ship Shock Trials Over a Maximum Year of Navy
Testing
[One event]
----------------------------------------------------------------------------------------------------------------
Maximum
Maximum Maximum annual non- Maximum
Species Stock annual TTS annual AUD auditory annual
INJ injury mortality
----------------------------------------------------------------------------------------------------------------
Blue Whale......................... Eastern North Pacific.. 12 - - -
Fin Whale.......................... California/Oregon/ 24 0 - -
Washington.
Humpback Whale..................... Central America/ 1 0 - -
Southern Mexico--
California/Oregon/
Washington.
Humpback Whale..................... Mainland Mexico-- 2 0 0 -
California/Oregon/
Washington.
Minke Whale........................ California/Oregon/ 1 0 - -
Washington.
Sei Whale.......................... Eastern North Pacific.. 0 - - -
Sperm Whale........................ California/Oregon/ 0 0 - -
Washington.
Dwarf Sperm Whale.................. California/Oregon/ 2 2 - -
Washington.
Pygmy Sperm Whale.................. California/Oregon/ 2 2 - -
Washington.
Baird's Beaked Whale............... California/Oregon/ 0 0 - -
Washington.
Goose-Beaked Whale................. California/Oregon/ 1 0 0 -
Washington.
Mesoplodont Beaked Whale........... California/Oregon/ 0 0 0 0
Washington.
Short-Finned Pilot Whale........... California/Oregon/ 0 - - -
Washington.
Bottlenose Dolphin................. California/Oregon/ 0 0 0 -
Washington Offshore.
Long-Beaked Common Dolphin......... California............. 4 1 1 1
Northern Right Whale Dolphin....... California/Oregon/ 0 0 0 0
Washington.
Pacific White-Sided Dolphin........ California/Oregon/ 1 - 0 0
Washington.
Pantropical Spotted Dolphin........ Baja California 1 0 0 0
Peninsula Mexico *.
Risso's Dolphin.................... California/Oregon/ 1 0 0 0
Washington.
Short-Beaked Common Dolphin........ California/Oregon/ 17 5 3 3
Washington.
Striped Dolphin.................... California/Oregon/ 0 0 0 -
Washington.
Dall's Porpoise.................... California/Oregon/ 39 34 - 0
Washington.
California Sea Lion................ U.S.................... 6 1 0 0
Guadalupe Fur Seal................. Mexico................. 0 - - -
Northern Elephant Seal............. California Breeding.... 6 4 0 0
----------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. The estimated takes in this
table are included in table 48 and not additional to table 48.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false
killer whale, pantropical spotted dolphin, and pygmy killer whales are not recognized stocks in NMFS Pacific
stock assessment report (Carretta et al., 2024), but separate density estimates were derived to support the
Navy's analysis.

[[Page 32247]]

Table 51--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Explosives During Coast Guard Training Activities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Maximum 7-
Maximum Maximum Maximum annual non- Maximum Maximum 7- Maximum 7- Maximum 7- year non- Maximum 7-
Species Stock annual annual annual auditory annual year year TTS year AUD auditory year
behavioral TTS AUD INJ injury mortality behavioral INJ injury mortality
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale................................. Eastern North Pacific........ 0 1 - - - 0 1 - - -
Blue Whale................................. Eastern North Pacific........ 1 - - - - 1 - - - -
Fin Whale.................................. California/Oregon/Washington. 0 0 0 - - 0 0 0 - -
Humpback Whale............................. Central America/Southern 0 0 - - - 0 0 - - -
Mexico--California/Oregon/
Washington.
Humpback Whale............................. Mainland Mexico--California/ 1 0 - - - 1 0 - - -
Oregon/Washington.
Minke Whale................................ California/Oregon/Washington. 0 0 - - - 0 0 - - -
Sei Whale.................................. Hawaii....................... - 0 - - - - 0 - - -
Sperm Whale................................ California/Oregon/Washington. 0 - - - - 0 - - - -
Dwarf Sperm Whale.......................... Hawaii....................... 1 1 1 - - 6 5 1 - -
Dwarf Sperm Whale.......................... California/Oregon/Washington. 1 1 1 - - 1 1 1 - -
Pygmy Sperm Whale.......................... Hawaii....................... 1 1 1 - - 7 3 1 - -
Pygmy Sperm Whale.......................... California/Oregon/Washington. 1 1 0 - - 1 1 0 - -
Goose-Beaked Whale......................... California/Oregon/Washington. 0 - - - - 0 - - - -
Mesoplodont Beaked Whale................... California/Oregon/Washington. 1 - 0 - - 1 - 0 - -
False Killer Whale......................... Baja California Peninsula 1 - 1 - - 1 - 1 - -
Mexico *.
Melon-Headed Whale......................... Hawaiian Islands............. 1 - - - - 1 - - - -
Bottlenose Dolphin......................... California/Oregon/Washington 1 1 - - - 1 1 - - -
Offshore.
Fraser's Dolphin........................... Hawaii....................... 1 0 - - - 1 0 - - -
Long-Beaked Common Dolphin................. California................... 1 1 0 - - 1 1 0 - -
Northern Right Whale Dolphin............... California/Oregon/Washington. 0 0 - - - 0 0 - - -
Pacific White-Sided Dolphin................ California/Oregon/Washington. 0 0 - - - 0 0 - - -
Pantropical Spotted Dolphin................ Hawaii Island................ 0 0 - - - 0 0 - - -
Pantropical Spotted Dolphin................ Hawaii Pelagic............... - 1 - - - - 1 - - -
Pantropical Spotted Dolphin................ Baja California Peninsula - 1 - - - - 1 - - -
Mexico *.
Risso's Dolphin............................ California/Oregon/Washington. 0 1 - - - 0 1 - - -
Rough-Toothed Dolphin...................... Hawaii....................... 0 - - - - 0 - - - -
Short-Beaked Common Dolphin................ California/Oregon/Washington. 3 2 1 - - 17 14 2 - -
Striped Dolphin............................ Hawaii Pelagic............... - 0 0 - - - 0 0 - -
Striped Dolphin............................ California/Oregon/Washington. - 1 - - - - 1 - - -
Dall's Porpoise............................ California/Oregon/Washington. 2 2 1 - - 11 9 3 - -
Harbor Porpoise............................ San Francisco/Russian River.. 0 0 0 - - 0 0 0 - -
California Sea Lion........................ U.S.......................... 2 2 0 0 - 10 8 0 0 -
Guadalupe Fur Seal......................... Mexico....................... 1 - - - - 2 - - - -
Northern Fur Seal.......................... Eastern Pacific.............. 0 1 - - - 0 1 - - -
Northern Fur Seal.......................... California................... 0 0 - - - 0 0 - - -
Harbor Seal................................ California................... 1 0 - - - 1 0 - - -
Northern Elephant Seal..................... California Breeding.......... 2 2 1 - - 8 11 1 - -
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1, that value has been rounded up from a
value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic
Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin, and pygmy killer whales are not
recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were derived to support the Navy's analysis.

Table 52--Annual and 7-Year Estimated Take of Marine Mammal Stocks From Explosives During Army Training Activities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Maximum 7-
Maximum Maximum Maximum annual non- Maximum Maximum 7- Maximum 7- Maximum 7- year non- Maximum 7-
Species Stock annual annual annual auditory annual year year TTS year AUD auditory year
behavioral TTS AUD INJ injury mortality behavioral INJ injury mortality
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Bryde's Whale.............................. Hawaii....................... 1 1 - - - 2 1 - - -
Humpback Whale............................. Hawaii....................... 3 1 - - - 15 7 - - -
Minke Whale................................ Hawaii....................... 1 - - - - 3 - - - -
Dwarf Sperm Whale.......................... Hawaii....................... 51 46 12 - - 355 322 84 - -
Pygmy Sperm Whale.......................... Hawaii....................... 57 51 15 - - 399 356 101 - -
Blainville's Beaked Whale.................. Hawaii....................... - 1 - - - - 1 - - -
Goose-Beaked Whale......................... Hawaii....................... 1 1 0 - - 3 3 0 - -

[[Page 32248]]

Longman's Beaked Whale..................... Hawaii....................... 1 1 - - - 2 1 - - -
Melon-Headed Whale......................... Hawaiian Islands............. 1 1 1 - - 5 3 1 - -
Melon-Headed Whale......................... Kohala Resident (Hawaii)..... 1 1 - - - 4 3 - - -
Pygmy Killer Whale......................... Hawaii....................... 1 - - - - 3 - - - -
Short-Finned Pilot Whale................... Hawaii....................... 2 1 1 1 - 9 6 2 1 -
Bottlenose Dolphin......................... Hawaii Pelagic............... 2 1 1 0 - 10 4 1 0 -
Fraser's Dolphin........................... Hawaii....................... 2 3 1 1 - 12 15 5 1 -
Pantropical Spotted Dolphin................ Maui Nui..................... - 1 - - - - 1 - - -
Pantropical Spotted Dolphin................ Hawaii Pelagic............... 2 1 1 1 0 8 6 1 1 0
Risso's Dolphin............................ Hawaii....................... - - 1 0 - - - 1 0 -
Rough-Toothed Dolphin...................... Hawaii....................... 3 2 1 1 - 17 14 1 1 -
Striped Dolphin............................ Hawaii Pelagic............... 1 2 1 1 - 7 10 1 1 -
Hawaiian Monk Seal......................... Hawaii....................... 1 - - - - 3 - - - -
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1, that value has been rounded up from a
value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic
Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin, and pygmy killer whales are not
recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were derived to support the Navy's analysis.

[[Page 32249]]

Estimated Take From Vessel Strike by Serious Injury or Mortality

Vessel strikes from commercial, recreational, and military vessels
are known to affect large whales and have resulted in serious injury
and fatalities to cetaceans (Abramson et al., 2011; Berman-Kowalewski
et al., 2010a; Calambokidis, 2012; Douglas et al., 2008; Laggner, 2009;
Lammers et al., 2003; Van der Hoop et al., 2013; Van der Hoop et al.,
2012). Records of vessel strikes of large whales date back to the early
17th century, and the worldwide number of vessel strikes of large
whales appears to have increased steadily during recent decades (Laist
et al., 2001; Ritter 2012).
Numerous studies of interactions between surface vessels and marine
mammals have demonstrated that free-ranging marine mammals often, but
not always (e.g., McKenna et al., 2015), engage in avoidance behavior
when surface vessels move toward them. It is not clear whether these
responses are caused by the physical presence of a surface vessel, the
underwater noise generated by the vessel, or an interaction between the
two (Amaral and Carlson, 2005; Au and Green, 2000; Bain et al., 2006;
Bauer 1986; Bejder et al., 1999; Bejder and Lusseau, 2008; Bejder et
al., 2009; Bryant et al., 1984; Corkeron, 1995; Erbe, 2002;
F[eacute]lix, 2001; Goodwin and Cotton, 2004; Greig et al., 2020;
Guilpin et al., 2020; Keen et al., 2019; Lemon et al., 2006; Lusseau,
2003; Lusseau, 2006; Magalhaes et al., 2002; Nowacek et al., 2001;
Redfern et al., 2020; Richter et al., 2003; Scheidat et al., 2004;
Simmonds, 2005; Szesciorka et al., 2019; Watkins, 1986; Williams et
al., 2002; Wursig et al., 1998). Several authors suggest that the noise
generated during motion is probably an important factor (Blane and
Jaakson, 1994; Evans et al., 1992; Evans et al., 1994). These studies
suggest that the behavioral responses of marine mammals to surface
vessels are similar to their behavioral responses to predators.
Avoidance behavior is expected to be even stronger in the subset of
instances during which the Action Proponents are conducting military
readiness activities using active sonar or explosives.
The marine mammals most vulnerable to vessel strikes are those that
spend extended periods of time at the surface in order to restore
oxygen levels within their tissues after deep dives (e.g., sperm
whales). In addition, some baleen whales seem generally unresponsive to
vessel sound, making them more susceptible to vessel strikes (Nowacek
et al., 2004). These species are primarily large, slow moving whales.
There are 8 species (17 stocks) of large whales that are known to occur
within the HCTT Study Area (table 14): gray whale, blue whale, Bryde's
whale, fin whale, humpback whale, minke whale, sei whale, and sperm
whale.
Some researchers have suggested the relative risk of a vessel
strike can be assessed as a function of animal density and the
magnitude of vessel traffic (e.g., Fonnesbeck et al., 2008; Vanderlaan
et al., 2008). Differences among vessel types also influence the
probability of a vessel strike. The ability of any vessel to detect a
marine mammal and avoid a collision depends on a variety of factors,
including environmental conditions, vessel design, size, speed, and
ability and number of personnel observing, as well as the behavior of
the animal. Vessel speed, size, and mass are all important factors in
determining if injury or death of a marine mammal is likely due to a
vessel strike. For large vessels, speed and angle of approach can
influence the severity of a strike. Large whales also do not have to be
at the water's surface to be struck. Silber et al. (2010) found that
when a whale is below the surface (about one to two times the vessel
draft), under certain circumstances (vessel speed and location of the
whale relative to the ship's centerline), there is likely to be a
pronounced propeller suction effect. This suction effect may draw the
whale into the hull of the ship, increasing the probability of
propeller strikes.
There are some key differences between the operation of military
and non-military vessels which make the likelihood of a military vessel
striking a whale lower than some other vessels (e.g., commercial
merchant vessels). Key differences include:
Military vessels have personnel assigned to stand watch at
all times, day and night, when moving through the water (i.e., when the
vessel is underway). Watch personnel undertake extensive training and
are certified to stand watch only after demonstrating competency in all
necessary skills. While on watch, personnel employ visual search and
reporting procedures in accordance with the U.S. Navy Lookout Training
Handbook, the Coast Guard's Shipboard Lookout Manual, or civilian
equivalent.
The bridges of many military vessels are positioned closer
to the bow, offering better visibility ahead of the vessel (compared to
a commercial merchant vessel);
Military readiness activities often involve aircraft
(which can serve as part of the Lookout team), that can more readily
detect cetaceans in the vicinity of a vessel or ahead of a vessel's
present course, often before crew on the vessel would be able to detect
them;
Military vessels are generally more maneuverable than
commercial merchant vessels, and are therefore capable of changing
course more quickly in the event cetaceans are spotted in the vessel's
path;
Military vessels operate at the slowest speed practical
consistent with operational requirements. While minimum speed is
intended as a fuel conservation measure particular to a certain ship
class, secondary benefits include a better ability to detect and avoid
objects in the water, including marine mammals;
Military ships often operate within a defined area for a
period of time, in contrast to point-to-point commercial shipping over
greater distances;
The crew size on military vessels is generally larger than
merchant vessels, allowing for stationing more trained Lookouts on the
bridge. At all times when the Action Proponents' vessels are underway,
trained Lookouts and bridge navigation teams are used to detect objects
on the surface of the water ahead of the ship, including cetaceans.
Some events may have additional personnel (beyond the minimum number of
required Lookouts) who are already standing watch in or on the platform
conducting the event or additional participating platforms and would
have eyes on the water for all or part of an event. These additional
personnel serve as members of the Lookout team; and
When submerged, submarines are generally slow moving (to
avoid detection); as a result, marine mammals at depth with a submarine
are likely able to avoid collision with the submarine. When a submarine
is transiting on the surface, the Navy posts Lookouts serving the same
function as they do on surface vessels.
Vessel strike to marine mammals is not associated with any specific
military readiness activity. Rather, vessel strike is a limited and
sporadic, but possible, accidental result of military vessel movement
within the HCTT Study Area or while in transit.
There were two recorded U.S. Navy vessel strikes of large whales in
the HSTT (now HCTT) Study Area in 2009. There were no known strikes
from June 2009 until May 2021, a period of approximately 12 years. (Of
note, between 2009-2024, the Navy documented 384 U.S. Navy vessel
movements in HSTT to avoid marine mammals during MTEs.) Since 2021
there have been five strikes of large whales in SOCAL attributed to
naval vessels, three by the U.S. Navy and two by the Royal Australian
Navy. As stated

[[Page 32250]]

previously, the U.S. Navy struck a large whale in waters off Southern
California in May 2023. Based on available photos and video, NMFS and
the Navy have determined this whale was either a fin whale or sei
whale. The U.S. Navy struck two unidentified large whales during the
months of June and July 2021, and prior to that, on May 7, 2021, the
Royal Australian Navy HMAS Sydney, a 147.5 m (161.3 yd) Hobart Class
Destroyer, struck and killed two fin whales (a mother and her calf)
while operating within SOCAL. Please see the Authorized Take From
Vessel Strikes and Explosives by Serious Injury or Mortality section of
the 2025 HSTT final rule (90 FR 4944, January 16, 2025) for detailed
descriptions of the naval vessel strikes that occurred in 2021 and
2023.
In March 2024 a dead fin whale was discovered off of Pier 10 in
Naval Station San Diego within the Navy's security barrier. The
security barrier, which consists of a series of connected floating
sections, is intended to discourage unauthorized boat entry to the
piers. The necropsy indicated that vessel strike was the most likely
cause of death. Given the location the whale was discovered, this could
have been the result of a military vessel strike. However, the Navy
reviewed its vessel activity during that time frame and available
observations of those vessels coming and going to port, as well as at
port, and determined it was unlikely that the whale was carried into
port by a Navy vessel. Based on this and other information from Navy's
investigation, we cannot determine whether this whale was struck by a
Navy vessel during HSTT activities or was struck by a commercial or
other vessel and drifted into the Navy pier area.
There has been one recorded Coast Guard vessel strike of a large
whale (humpback) in the HCTT Study Area since 2009. The strike occurred
in 2020 off Maui, HI. There have been no known strikes within the
California portion of the HCTT Study Area. However, there were two
Coast Guard strikes outside of and inshore of the California portion of
the HCTT Study Area, a humpback whale in 2023 and a gray whale in 2024.
The vessels involved in the 2023 and 2024 strikes were moving at slow
speed less than 6 kn and no obvious injury to the whales were observed
after the strikes.
In light of the key differences between the operation of military
and non-military vessels discussed above, it is highly unlikely that a
military vessel would strike any type of marine mammal without
detecting it. Specifically, Lookouts posted on or near the ship's bow
can visually detect a strike in the absence of other indications that a
strike has occurred. The Action Proponents' internal procedures and
mitigation requirements include reporting of any vessel strikes of
marine mammals, and the Action Proponents' discipline, extensive
training (not only for detecting marine mammals, but for detecting and
reporting any potential navigational obstruction), and strict chain of
command give NMFS a high level of confidence that all strikes are
reported. Accordingly, NMFS is confident that the Navy and Coast
Guard's reported strikes are accurate and appropriate for use in the
analysis.
When generally compared to mysticetes, odontocetes are more capable
of physically avoiding a vessel strike and since some species occur in
large groups, they are more easily seen when they are closer to the
water surface. The smaller size and maneuverability of dolphins, small
whales (not including large whale calves), porpoises, and pinnipeds
generally make vessel strike very unlikely. For as long as records have
been kept, neither the Navy nor the Coast Guard have any record of any
small whales or pinnipeds being struck by a vessel as a result of
military readiness activities. Over the same time period, NMFS, the
Navy, and the Coast Guard have only one record of a dolphin being
struck by a vessel as a result of Navy or Coast Guard activities. The
dolphin was accidentally struck by a Navy small boat in fall 2021 in
Saint Andrew's Pass, Florida. Other than this one reported strike of a
dolphin in 2021, NMFS has never received any reports from other LOA or
IHA holders indicating that these species have been struck by vessels.
Worldwide vessel strike records show little evidence of strikes of
these groups or marine mammals from the shipping sector and larger
vessels (though for many species, records do exist (e.g., West et al.
2024, Van Waerebeek et al., 2007)), and the majority of the Action
Proponents' activities involving faster-moving vessels (that could be
considered more likely to hit a marine mammal) are located in offshore
areas where smaller delphinid, porpoise, and pinniped densities are
lower.
In order to account for the accidental nature of vessel strike to
large whales in general, and the potential risk from vessel movement
within the HCTT Study Area within the 7-year period of this proposed
authorization, the Action Proponents requested incidental takes based
on probabilities derived from a Poisson distribution. A Poisson
distribution is often used to describe random occurrences when the
probability of an occurrence is small. Count data, such as cetacean
sighting data, or in this case strike data, are often described as a
Poisson or over-dispersed Poisson distribution. The Poisson
distribution was calculated using vessel strike data between 2009-2024
in the HCTT Study Area, historical at-sea days in the HCTT Study Area
for the Navy and the Coast Guard (described in detail in section 6 of
the application), and estimated potential at-sea days for both Action
Proponents during the 7-year period from 2025-2032 covered by the
requested regulations. The analysis incorporates data beginning in 2009
as that was the start of the Navy's Marine Species Awareness Training
and adoption of additional mitigation measures to address vessel
strike, which will remain in place along with additional and modified
mitigation measures during the 7 years of this proposed rulemaking. The
analysis for the period of 2025 to 2032 is described in detail below
and in section 6.3.2 (Probability of Vessel Strike of Large Whale
Species) of the application.
Between 2009 and early 2024, there were a total of 35,006 Navy at-
sea days for Navy manned vessels greater than 127 m (418 ft, or
Littoral Combat Ship size and above) in the HCTT Study Area, an average
2,188 days per year. This estimate is based on positional tracking data
records from the Navy's Authoritative Maritime Services database for
the years 2016-2023. The Navy used the average of the 2016-2023 annual
values as a surrogate for annual at-sea days for each year between 2009
and 2015. Given variation in vessel traffic from year to year, the Navy
anticipates that the annual average from this period is a sufficient
prediction of future at-sea days for manned surface ships for the
period of this proposed rule (i.e., 2025-2032) (i.e., 2,188 days per
year). In addition, this vessel strike analysis considers the potential
for larger sized USVs (longer than 61 m (200 ft)) to strike a large
whale, as these vessels would be used for military readiness activities
during the proposed effective period of this proposed rule. While there
have been no known vessel strikes from USVs, this analysis incorporates
an estimated 728 at-sea days for large USVs, for a predicted total of
2,916 annual at-sea days from large, manned vessels and large USVs from
2025-2032 (i.e., 20,412 at-sea days over the 7-year period).
Between 2009 and early 2024, there were a total of 4,179 Coast
Guard at-sea days for vessels larger than 100 m (328 ft) in the HCTT
Study Area, an average of 262 days per year. To account for limitations
in data availability particular

[[Page 32251]]

to Coast Guard vessel size classes, future new vessel or repositioning
home port assignments, in consideration of documented strikes from
Coast Guard medium sized vessels <100 m, and out of an abundance of
caution, the Coast Guard predicted that there could be up to 60
additional at-sea days per year for the 2025-2032 period, for a
predicted total of 322 annual at-sea days for vessels that may strike a
large whale from 2025-2032 (i.e., 2,254 at-sea days over the 7-year
period).
As described above, during the same 2009 to 2024 period, there were
five Navy vessel strikes of large whales and one Coast Guard vessel
strike of a large whale. To calculate a vessel strike rate for each
Action Proponent for the period of 2009 through 2024, the Action
Proponents used the respective number of past vessel strikes of large
whales and the respective number of at-sea days. Navy at-sea days (for
vessels greater than 65 ft (19.8 m)) from 2009 through 2024 was
estimated to be 35,006 days. Dividing the five known Navy strikes
during that period by the at-sea days (i.e., 5 strikes/35,006 at-sea
days) results in a strike rate of 0.000143 strikes per at-sea day.
Coast Guard at-sea days from 2009 through 2024 was estimated to be
4,179 days. Dividing the one known Coast Guard strike during that
period by the at-sea days (i.e., 1 strike/4,179 at-sea days) results in
a strike rate of 0.000239 strikes per day.
As described above, the Action Proponents estimated that 20,412
Navy and 2,254 Coast Guard at-sea days would occur over the 7-year
period associated with the requested authorization. Given a strike rate
of 0.000143 Navy strikes per at-sea day, and 0.000239 Coast Guard
strikes per at-sea day, the predicted number of vessel strikes over a
7-year period would be 2.9 strikes by the Navy and 0.5 strikes by the
Coast Guard.
Using this predicted number of strikes, the Poisson distribution
predicted the probabilities of a specific number of strikes (n = 0, 1,
2, etc.) from 2025 through 2032 for each Action Proponent. The
probability analysis concluded that there is a 95 percent chance that a
Navy vessel would strike at least one whale over the 7-year period, and
a 79, 56, 34, 17, or 8 percent chance that more than one, two, three,
four, or five whales, respectively, would be struck by the Navy over
the 7-year period.
The probability analysis concluded that there is a 42 percent
chance that a Coast Guard vessel would strike at least one whale over
the 7-year period, and a 10 or 1 percent chance that more than one or
two whales, respectively, would be struck by the Coast Guard over the
7-year period.
Based on this analysis, the Navy is requesting authorization to
take five large whales by serious injury or mortality by vessel strike
incidental to Navy training and testing activities, and the Coast Guard
is requesting authorization to take two large whales by serious injury
or mortality by vessel strike incidental to Coast Guard training
activities. NMFS concurs that take by serious injury or mortality by
vessel strike of up to five large whales by the Navy and two large
whales by the Coast Guard (seven large whales total) could occur over
the 7-year regulations and, based on the information provided earlier
in this section, NMFS concurs with the Action Proponents' assessment
and recognizes the potential for incidental take by vessel strike of
large whales only (i.e., no dolphins, small whales (not including large
whale calves), porpoises, or pinnipeds) over the course of the 7-year
regulations from military readiness activities.
While the Poisson distribution allows the Action Proponents and
NMFS to determine the likelihood of vessel strike of all large whales,
it does not indicate the likelihood of each strike occurring to a
particular species or stock. As described above, the Action Proponents
have not always been able to identify the species of large whale struck
during previous known vessel strikes. However, based on the information
available, the Navy requested authorization for take by serious injury
or mortality by vessel strike of five whales, and of those five, no
more than the following numbers from these stocks: one blue whale
(Eastern North Pacific stock), four fin whales (California/Oregon/
Washing (CA/OR/WA) stock), two gray whales (Eastern North Pacific
stock), two humpback whale (one each of the Mainland Mexico-CA/OR/WA
stock and the Central North Pacific stock), and one sperm whale (Hawaii
stock). The Coast Guard requested authorization for take by serious
injury or mortality by vessel strike of two whales, and of those two,
no more than the following numbers from these stocks: one blue whale
(Eastern North Pacific stock), two fin whales (CA/OR/WA stock), two
gray whales (Eastern Pacific stock), and two humpback whales (one each
of the Mainland Mexico-CA/OR/WA stock and Central North Pacific stock).
After concurring that take of up to seven large whales could occur
(five takes by Navy, two by Coast Guard), and in consideration of the
Action Proponents' request, NMFS considered which species could be
among the seven large whales struck. NMFS conducted an analysis that
considered several factors, in addition to the overlap of Navy
activities with stock distribution: (1) the relative likelihood of
striking one stock versus another based on available strike data from
all vessel types as denoted in the SARs, and (2) whether each Action
Proponent has ever struck an individual from a particular species or
stock in the HCTT Study Area, and if so, how many times.
To address number (1) above, for SOCAL, NMFS compiled information
from the 2023 SARs (Carretta et al., 2024, Young et al., 2024) on
detected annual rates of large whale M/SI from vessel strike (table
53). (Of note, these data include the strike of two fin whales by the
Royal Australian Navy in 2021, but do not include Navy strikes in 2021
and 2023 because the species struck is not known.) The M/SI in the 2023
SAR considers modeled takes (accounting for undetected vessel strike
mortality) for some, but not most species and stocks (i.e., M/SI for
humpback whale includes modeled takes from Rockwood et al. (2017)).
Using known strike data for all species and stocks allows NMFS to
consider similar metrics for this comparative analysis. (Note that we
rely on the M/SI estimates from the 2023 SAR (or draft 2024 SAR, where
relevant) in our negligible impact analysis.) We also consider modeled
takes of species from Rockwood et al. (2017) in table 53. The annual
rates of large whale serious injury or mortality from vessel strike
reported in the SARs help inform the relative susceptibility of large
whale species to vessel strike in HCTT Study Area as recorded
systematically over the five-year period used for the SARs. We summed
the annual rates of serious injury or mortality from vessel strikes as
reported in the SARs (excluding strikes that the SAR indicates occurred
outside of the Study Area (e.g., in Alaska)) and then divided each
species' annual rate by this sum to get the percentage of total annual
strikes for each species/stock (table 53).

[[Page 32252]]

Table 53--Summary of Factors Considered in Determining the Number of Individuals in Each Stock Potentially Struck by a Vessel
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total known
U.S. Navy or Rockwood et Annual rate Percentage Percent Percent Percent
Species Stock Coast Guard al. (2017) of M/SI of total likelihood of likelihood of likelihood of
strikes in HCTT modeled vessel from vessel annual 1 strike over 2 strikes over 3 strikes over
study area strikes \a\ strike \b\ strikes 7 years 7 years 7 years
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale.................. Eastern North Navy 2004...... 18 0.6 6.06 5.76 0.33 0.02
Pacific.
Fin whale................... California/ Navy 2009; Navy 43 1.6 16.16 15.35 2.36 0.36
Oregon/ 2009; Navy
Washington. 2023 (fin or
sei).
Humpback whale.............. Mainland Mexico- Coast Guard 22 2.6 26.26 24.95 6.22 1.55
California- 2016 (northern
Oregon- California)
Washington. \c\.
Humpback whale.............. Central America/
Southern
Mexico-
California-
Oregon-
Washington.
Sperm whale................. Hawaii......... Navy 2007...... .............. 0.0 0.00 UNK UNK UNK
Gray whale.................. Eastern North Navy 1993; Navy .............. 1.8 18.18 17.27 2.98 0.52
Pacific. 1998; Navy
1998.
Humpback whale.............. Hawaii......... Navy 1998; Navy .............. 3.3 33.33 31.67 10.03 3.18
2003; Coast
Guard 2020.
Sei whale................... Eastern North Navy 2023 (fin .............. 0.0 0.0 0.00 0.00 0.00
Pacific. or sei).
Sei whale................... Hawaii......... ............... .............. 0.0 0.0 0.00 0.00 0.00
Sperm whale................. California/ ............... .............. 0.0 0.0 0.00 0.00 0.00
Oregon/
Washington.
Bryde's whale............... Eastern ............... .............. 0.0 0.0 0.00 0.00 0.00
Tropical
Pacific.
Bryde's whale............... Hawaii......... ............... .............. 0.0 0.0 0.00 0.00 0.00
Minke whale................. Hawaii......... ............... .............. 0.0 0.0 0.00 0.00 0.00
Minke whale................. California/ ............... .............. 0.0 0.0 0.00 0.00 0.00
Oregon/
Washington.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Rockwood et al. (2017) modeled likely annual vessel strikes off the West Coast for these three species only.
\b\ Values are from the most recent stock assessment report (Carretta et al., 2024).
\c\ The strike by the Coast Guard in 2016 was in San Francisco Bay, CA, outside the boundary of the HCTT Study Area.

To inform the likelihood of a single action proponent striking a
particular species of large whale, we multiplied the percent of total
annual strikes for a given species in table 53 by the total percent
likelihood of a single action proponent striking at least one whale
(i.e., 95 and 42 percent for the Navy and Coast Guard, respectively, as
described by the probability analysis above). We also calculated the
percent likelihood of a single action proponent striking a particular
species of large whale two or three times by squaring or cubing,
respectively, the value estimated for the probability of striking a
particular species of whale once (i.e., to calculate the probability of
an event occurring twice, multiply the probability of the first event
by the second). The results of these calculations are reflected in the
last three columns of table 53. We note that these probabilities vary
from year to year as the average annual mortality changes depending on
the specific range of time considered; however, over the years and
through updated data in the SARs, stocks tend to consistently maintain
a relatively higher or relatively lower likelihood of being struck.
The percent likelihood calculated (as described above) are then
considered in combination with the information indicating the known
species that the Navy or Coast Guard has struck in the HCTT Study Area
since 1991 (since they started tracking consistently) (see table 53).
We note that for the lethal take of species specifically denoted in
table 53, 47 percent of those struck by the Navy (8 of 17 in the
Pacific) remained unidentified (including the May 2023 strike, which as
stated above, NMFS and the Navy have determined was of either a fin
whale or sei whale), and 20 percent of those struck by the Coast Guard
(1 of 5 in the Pacific) remained unidentified. However, given the
information on known stocks struck, the analysis below remains
appropriate. We also note that Rockwood et al. (2017) modeled the
likelihood of vessel strike of blue whales, fin whales, and humpback
whales on the U.S. West Coast (discussed in more detail in the Serious
Injury or Mortality subsection of the Preliminary Analysis and
Negligible Impact Determination section), and those numbers help inform
the relative likelihood that the Navy or Coast Guard could strike those
stocks.
Accordingly, stocks that have no record of ever having been struck
by any vessel are considered to have a zero percent likelihood of being
struck by the Navy or Coast Guard in the 7-year period of the proposed
rule. Marine mammal stocks that have never been struck by the Navy or
Coast Guard, have rarely been struck by other vessels, and have a low
percent likelihood based on the historical vessel strike calculation
are also considered to have a zero percent likelihood to be struck by
the Navy or Coast Guard during the 7-year rule. We note that while
vessel strike records have not differentiated between Eastern North
Pacific and Western North Pacific gray whales, given their small
population size and the comparative rarity with which individuals from
the Western North Pacific stock are detected off the U.S. West Coast,
it is highly unlikely that they would be encountered, much less struck.
This rules out all but eight stocks. This leaves the following stocks
for further analysis: blue whale (Eastern North Pacific stock), fin
whale (CA/OR/WA stock), gray whale (Eastern North Pacific stock),
humpback whale (Mainland Mexico-CA/OR/WA, Central America/Southern
Mexico-CA/OR/WA, and Hawaii stocks), sei whale (Eastern North Pacific
stock), and sperm whale (Hawaii stock).
As stated previously, based on available photos and video of the
whale struck by the U.S. Navy in Southern

[[Page 32253]]

California in 2023, NMFS and the Navy have determined this whale was
either a fin whale or sei whale. While the species of the two whales
struck by the U.S. Navy in 2021 are unknown, given the following
factors, NMFS expects these strikes may have been CA/OR/WA fin whales
or Eastern North Pacific gray whales, or some combination of these two
stocks. These species have the highest annual rates of M/SI from vessel
collision in California (1.6, 1.8, respectively, as noted above).
Additionally, gray whale and fin whale have the most recorded vessel
strike incidents by military vessels in California and are the only
stocks known to have been hit more than one time by naval or Coast
Guard vessels in the California portion of the study area (three gray
whale strikes by the U.S. Navy (1993, 1998), two or three fin whale
strikes by the U.S. Navy (2009, potentially 2023), and two fin whale
strikes by the Royal Australian Navy (2021)). Further, accounting for
undocumented vessel strikes, Rockwood et al. (2021) estimated that in
their study area off Southern California from 2012-2018, on average 8.9
blue, 4.6 humpback, and 9.7 fin whales were killed by civilian vessel
strikes from June to November each year. In addition, they estimated
that, on average, 5.7 humpback whales were killed by civilian vessel
strike from January-April per year (Rockwood et al. 2021). For fin
whales in particular, model-predicted densities of large whales in the
Southern California Bight from May to July 2021 (the time period during
which the 2021 strikes of two unidentified whales by the U.S. Navy
occurred) estimated fin whale abundance as being nearly an order of
magnitude higher than either blue or humpback whale abundance during
this time period (Becker et al. 2020b; Zickel et al. 2021). Ship-whale
encounter models for the U.S. West Coast Exclusive Economic Zone also
indicated that vessel strike mortality estimates for fin whales were
significantly higher than for blue whales and humpback whales (Rockwood
et al. 2017). The comparatively higher modeled vessel strike rates for
fin whales result from both the larger population as well as the more
offshore distribution that overlaps significantly with several major
shipping routes for a much greater spatial extent (Rockwood et al.
2017). Based on 1,243 visual boat-based sightings of 2,638 fin whales
from 1991-2011, Calambokidis et al. (2015) found fin whale
concentration areas included the San Clemente Basin where the 2021 Navy
vessel strikes occurred. Tanner and Cortes Banks area and the shelf
edge west of SNI were also reported as fin whale concentration areas.
There are two different populations of fin whales that occur in the
Southern California Bight: a seasonal population, and a population that
occurs year-round with offshore/inshore movements (Campbell et al.
2015; Falcone et al. 2022). This would likely make fin whales more
susceptible to vessel strike year-round, as compared to other large
whale species that may occur seasonally within SOCAL. Therefore, we
find that, of the five total takes by serious injury or mortality by
vessel strike of large whales proposed for authorization for the Navy
over the course of the 7-year rule, up to three of those takes could be
of the CA/OR/WA stock of fin whale and up to two could be of the
Eastern North Pacific stock of gray whale given that the two strikes of
unidentified large whales in 2021 could have been of either stock.
Further, we expect that, of the five total takes by serious injury or
mortality by vessel strike of large whales proposed for authorization
for the Navy, up to two of those takes could occur in Hawaii, and
therefore be of individuals of the Hawaii stock of humpback whale. NMFS
expects that, of the two total takes by serious injury or mortality by
vessel strike of large whales proposed for authorization for the Coast
Guard, one of those takes could be of the CA/OR/WA stock of fin whale,
Eastern North Pacific stock of gray whale, or Hawaii stock of humpback
whale. (Coast Guard struck a humpback whale in Hawaii in 2020.)
For U.S. Navy vessel strikes in California, based on the
information summarized in table 53 and the fact that there is the
potential for up to five large whales to be struck by the Navy over the
7-year rule, one individual from the Eastern North Pacific stock of
blue whale, Mainland Mexico-CA/OR/WA and Central America/Southern
Mexico CA/OR/WA stocks of humpback whale, or Eastern North Pacific
stock of sei whale could be among the five whales struck. The total
strikes of Eastern North Pacific blue whales and the percent likelihood
of striking one based on the historic strike calculation above can both
be considered moderate compared to other stocks, and the Navy struck a
blue whale in 2004 (based on the historic strike calculation, the
likelihood of striking two blue whales is well below one percent (table
52)). Therefore, we consider it reasonably likely that the Navy could
strike one individual over the course of the 7-year proposed rule. The
total strikes of Eastern North Pacific sei whales are low (i.e., 0)
compared to other stocks, but NMFS and the Navy think it is possible
that the Navy may have struck a sei whale in SOCAL in 2023. Therefore,
we consider it reasonably likely that the Navy could strike a sei whale
over the period of the rule. The Navy has not struck a humpback whale
in the California portion of the HCTT Study Area. However, in 2016 a
U.S. Coast Guard vessel struck a humpback whale heading out of San
Francisco Bay, and as a species, humpbacks have a high number of total
strikes and percent likelihood of being struck. The likelihood of
Central America/Southern Mexico-CA/OR/WA (Central America DPS) or
Mainland Mexico-CA/OR/WA (Mexico DPS) humpback whales being struck by
any vessel type is moderate to high relative to other stocks, and NMFS
anticipates that the Navy could strike one individual humpback whale
from the Mainland Mexico-CA/OR/WA stock (Mexico DPS) and/or one
individual from the Central America/Southern Mexico- CA/OR/WA (Central
America DPS) over the 7-year duration of the rule.
For Coast Guard vessel strikes in California, NMFS anticipates that
the Coast Guard may potentially strike the same species as listed above
for the Navy. Based on the information summarized in table 53 and the
fact that there is the potential for up to two large whales to be
struck by the Coast Guard over the 7-year rule, one individual from the
Eastern North Pacific stock of blue whale, CA/OR/WA stock of fin whale,
Mainland Mexico-CA/OR/WA and Central America/Southern Mexico CA/OR/WA
stocks of humpback whale, Eastern North Pacific stock of gray whale, or
Eastern North Pacific stock of sei whale could be among the two whales
struck. While, as noted above, NMFS anticipates that the U.S. Navy is
more likely to strike a fin whale than some other stocks, NMFS does not
anticipate that the same is true for the Coast Guard, as its vessel
traffic is not concentrated in the area where previous known Navy
vessel strikes of fin whales have occurred. Given the lower potential
total number of vessel strikes by the Coast Guard, NMFS does not
anticipate that the Coast Guard is likely to strike more than one of
any given species.
For Hawaii stocks, given that all known vessel strikes between 2015
and 2021 were of humpback whales, we anticipate that any vessel strike
of a large whale in Hawaii would likely be of the Hawaii stock of
humpback whale. Given that this stock has the highest percentage of
total annual strikes (33.3 percent) and a 10.3 percent chance of

[[Page 32254]]

being struck twice over the effective period of the rule, NMFS is
proposing to authorize two lethal takes of Hawaii humpback whales for
the Navy and one for the Coast Guard. NMFS also anticipates that the
Navy may strike up to one Hawaii sperm whale given the 2007 sperm whale
strike. Given the already lower likelihood of striking the Hawaii stock
of sperm whales, the relatively lower vessel activity in the Hawaii
portion of the HCTT Study Area, and the relatively lower Coast Guard
vessel traffic compared to Navy vessel traffic, NMFS neither
anticipates, nor proposes to authorize, a Coast Guard strike of this
stock.
As described above, the Navy's analysis suggests and NMFS' analysis
concurs that the likelihood of vessel strikes to the stocks below is
discountable due to the stocks' relatively low occurrence in the HCTT
Study Area, particularly in core HCTT training and testing subareas,
and the fact that the stocks have not been struck by the Navy and are
rarely, if ever, recorded struck by other vessels. Therefore, NMFS is
not authorizing lethal take for the following stocks: blue whale
(Central North Pacific stock), Bryde's whale (Eastern Tropical Pacific
stock and Hawaii stock), fin whale (Hawaii stock), gray whale (Western
North Pacific stock), minke whale (CA/OR/WA stock and Hawaii stock),
sei whale (Hawaii stock), and sperm whale (CA/OR/WA stock).
Also of note, while information on past Navy vessel strikes can
serve as a reasonable indicator of future vessel strike risk, future
conditions may differ from the past in ways that could influence the
likelihood of a large whale vessel strike occurring. In general, the
magnitude of vessel strike risk may be increasing over time as many
whale populations are gradually recovering from centuries of commercial
whaling (Redfern et al. 2020). Increased vessel strike risk off
California in recent decades has been associated with increases in the
abundance of fin and humpback whale populations in the North Pacific
(Redfern et al. 2020). It has also been suggested that the blue whale
population in the Eastern North Pacific, inclusive of the California
portion of the HCTT Study Area, is at carrying capacity and recovered
to pre-whaling levels (Monnahan et al. 2014). In addition, the
magnitude of risk may also be affected by shifts in whale distributions
over time in response to environmental factors including marine
heatwaves and associated changes in prey distribution.
Historically, military vessel strikes of large whales within the
HCTT Study Area have been rare events with only eight such strikes
occurring over the past 14 years, five U.S. Navy strikes, one Coast
Guard strike, and two Royal Australian Navy strikes. However, the fact
that four of these strikes occurred within a 3-month period (May-July)
in 2021, and two occurred within a 4-month period (February-May) in
2009, suggests that military vessel strikes in California can be both
highly episodic and clustered. The four large whale strikes in 2021
(two strikes of unidentified large whales by the U.S. Navy and two fin
whale strikes by the Royal Australian Navy) appear to be outliers in
the time series of military vessel strikes in SOCAL for that period.
Particularly in consideration of the 2023 U.S. Navy strike, these
strikes could also represent an early indicator of an increased
military vessel strike risk within SOCAL based on the factors discussed
above. Results from a survey of whale watching vessel operators and
crew in Southern California, combined with remote sensing data in the
area, suggest that the number of large whales may have been greater in
May through July of 2021 compared with previous years in certain high
military vessel traffic and ``core'' use HCTT areas off southern
California, particularly farther offshore as well as closer to shore
off San Diego Bay (Zickel et al., 2021).
In conclusion, while take by vessel strike across any given year is
sporadic, based on the information and analysis above, including
consideration of the 2021 and 2023 strikes by the U.S. Navy, NMFS
anticipates no more than seven takes of large whales by M/SI could
occur over the 7-year period of the rule (no more than five by Navy, no
more than two by Coast Guard). Of those seven whales over the 7-years,
no more than four may come from the CA/OR/WA stock of fin whale. No
more than three may come from the following stocks: gray whale (Eastern
North Pacific stock); and humpback whale (Hawaii stock). No more than
two may come from the following stocks: blue whale (Eastern North
Pacific stock); sei whale (Eastern North Pacific); and humpback whale
(Mainland Mexico-CA/OR/WA and Central America/Southern Mexico-CA/OR/WA
stocks (Mexico and Central America DPSs, respectively)). No more than
one may come from the Hawaii stock of sperm whale. (Note that these
species and stock conclusions vary slightly from that requested by Navy
and Coast Guard.) Accordingly, NMFS has evaluated under the negligible
impact standard the M/SI of 0.14, 0.29, 0.43, or 0.57 whales annually
from each of these species or stocks (i.e., one, two, three, or four
takes, respectively, divided by 7 years to get the annual number),
along with the expected incidental takes by harassment.

Summary of Requested Take From Military Readiness Activities

Table 54 and table 55 summarize the Action Proponents' take
proposed by harassment type and effect type, respectively.

Table 54--Total Annual and 7-year Incidental Take Proposed by Stock During All Activities by Harassment Type
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Maximum 7-Year 7-Year
annual annual Maximum total Level total Level 7-Year
Species Stock Level B Level A annual B A total
harassment harassment mortality harassment harassment mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale................................. Eastern North Pacific........ 16,711 167 0.43 87,292 1,010 3
Gray Whale................................. Western North Pacific........ 169 2 0 852 5 0
Blue Whale................................. Central North Pacific........ 92 1 0 524 2 0
Blue Whale................................. Eastern North Pacific........ 4,571 27 0.29 24,808 150 2
Bryde's Whale.............................. Eastern Tropical Pacific..... 322 5 0 1,874 14 0
Bryde's Whale.............................. Hawaii....................... 409 3 0 2,356 11 0
Fin Whale.................................. Hawaii....................... 86 1 0 487 1 0
Fin Whale.................................. California/Oregon/Washington. 13,501 55 0.57 68,558 300 4
Humpback Whale............................. Central America/Southern 1,888 19 0.29 9,898 96 2
Mexico-California/Oregon/
Washington.
Humpback Whale............................. Mainland Mexico-California/ 4,449 44 0.29 23,370 220 2
Oregon/Washington.
Humpback Whale............................. Hawaii....................... 3,034 24 0.43 18,945 151 3
Minke Whale................................ Hawaii....................... 296 3 0 1,698 13 0

[[Page 32255]]

Minke Whale................................ California/Oregon/Washington. 2,993 32 0 16,116 193 0
Sei Whale.................................. Hawaii....................... 253 2 0 1,437 5 0
Sei Whale.................................. Eastern North Pacific........ 302 3 0.29 1,611 9 2
Sperm Whale................................ Hawaii....................... 1,649 1 0.14 9,619 1 1
Sperm Whale................................ California/Oregon/Washington. 3,891 3 0 20,606 5 0
Dwarf Sperm Whale.......................... Hawaii....................... 45,224 915 0 262,401 5,103 0
Dwarf Sperm Whale.......................... California/Oregon/Washington. 5,664 94 0 30,093 517 0
Pygmy Sperm Whale.......................... Hawaii....................... 45,787 936 0 265,322 5,221 0
Pygmy Sperm Whale.......................... California/Oregon/Washington. 5,615 107 0 29,868 609 0
Baird's Beaked Whale....................... California/Oregon/Washington. 10,174 0 0 56,149 0 0
Blainville's Beaked Whale.................. Hawaii....................... 7,542 0 0 46,004 0 0
Goose-Beaked Whale......................... Hawaii....................... 30,359 0 0 185,039 0 0
Goose-Beaked Whale......................... California/Oregon/Washington. 166,816 2 0 939,012 4 0
Longman's Beaked Whale..................... Hawaii....................... 18,316 1 0 112,152 4 0
Mesoplodont Beaked Whale................... California/Oregon/Washington. 92,839 2 0 520,938 6 0
False Killer Whale......................... Main Hawaiian Islands Insular 169 0 0 1,009 0 0
False Killer Whale......................... Northwest Hawaiian Islands... 191 0 0 1,165 0 0
False Killer Whale......................... Hawaii Pelagic............... 1,670 1 0 9,865 1 0
False Killer Whale......................... Baja California Peninsula 2,537 2 0 13,888 2 0
Mexico.
Killer Whale............................... Hawaii....................... 127 0 0 733 0 0
Killer Whale............................... Eastern North Pacific 1,023 4 0 6,089 23 0
Offshore.
Killer Whale............................... West Coast Transient......... 55 0 0 261 0 0
Melon-Headed Whale......................... Hawaiian Islands............. 31,456 13 0 183,773 68 0
Melon-Headed Whale......................... Kohala Resident (Hawaii)..... 56 0 0 332 0 0
Pygmy Killer Whale......................... Hawaii....................... 8,895 3 0 52,059 8 0
Pygmy Killer Whale......................... California--Baja California 795 0 0 4,358 0 0
Peninsula Mexico.
Short-Finned Pilot Whale................... Hawaii....................... 17,304 7 0 104,772 26 0
Short-Finned Pilot Whale................... California/Oregon/Washington. 4,279 11 0.57 24,532 56 4
Bottlenose Dolphin......................... Maui Nui..................... 326 0 0 2,151 0 0
Bottlenose Dolphin......................... Hawaii Island................ 9 0 0 44 0 0
Bottlenose Dolphin......................... Hawaii Pelagic............... 43,313 25 0.29 287,119 163 2
Bottlenose Dolphin......................... Kaua[revaps]i/Ni[revaps]ihau. 1,460 0 0 9,314 0 0
Bottlenose Dolphin......................... O[revaps]ahu................. 7,232 6 0.14 50,375 30 1
Bottlenose Dolphin......................... California Coastal........... 1,350 7 0 8,761 42 0
Bottlenose Dolphin......................... California/Oregon/Washington 28,058 15 0 157,628 83 0
Offshore.
Fraser's Dolphin........................... Hawaii....................... 35,480 8 0 210,526 34 0
Long-Beaked Common Dolphin................. California................... 296,878 152 2.43 1,804,793 952 17
Northern Right Whale Dolphin............... California/Oregon/Washington. 45,514 21 0.14 224,039 96 1
Pacific White-Sided Dolphin................ California/Oregon/Washington. 69,210 42 0.29 361,049 242 2
Pantropical Spotted Dolphin................ Maui Nui..................... 2,373 4 0 15,192 18 0
Pantropical Spotted Dolphin................ Hawaii Island................ 6,024 7 0 35,584 25 0
Pantropical Spotted Dolphin................ Hawaii Pelagic............... 44,390 19 0 262,155 81 0
Pantropical Spotted Dolphin................ O[revaps]ahu................. 6,426 6 0 44,200 23 0
Pantropical Spotted Dolphin................ Baja California Peninsula 97,626 47 0.29 535,681 239 2
Mexico.
Risso's Dolphin............................ Hawaii....................... 6,558 4 0 38,040 5 0
Risso's Dolphin............................ California/Oregon/Washington. 43,833 21 0 240,847 125 0
Rough-Toothed Dolphin...................... Hawaii....................... 96,873 36 0.29 587,819 196 2
Short-Beaked Common Dolphin................ California/Oregon/Washington. 2,169,554 877 15.29 11,804,423 5,075 107
Spinner Dolphin............................ Hawaii Pelagic............... 4,544 2 0 26,539 4 0
Spinner Dolphin............................ Hawaii Island................ 110 1 0 644 1 0
Spinner Dolphin............................ Kaua[revaps]i/Ni[revaps]ihau. 4,446 2 0 28,334 6 0
Spinner Dolphin............................ O[revaps]ahu/4 Islands Region 1,201 1 0 8,205 2 0
Striped Dolphin............................ Hawaii Pelagic............... 37,782 12 0 219,594 52 0
Striped Dolphin............................ California/Oregon/Washington. 133,399 44 0.14 724,174 231 1
Dall's Porpoise............................ California/Oregon/Washington. 59,619 1,237 0 305,432 6,786 0
Harbor Porpoise............................ Monterey Bay................. 2,179 0 0 10,934 0 0
Harbor Porpoise............................ Morro Bay.................... 4,373 88 0 26,316 590 0
Harbor Porpoise............................ Northern California/Southern 481 0 0 2,339 0 0
Oregon.
Harbor Porpoise............................ San Francisco/Russian River.. 9,960 26 0 48,900 169 0
California Sea Lion........................ U.S.......................... 1,899,749 723 3.86 10,628,139 4,572 27
Guadalupe Fur Seal......................... Mexico....................... 347,553 54 0.14 1,900,834 300 1
Northern Fur Seal.......................... Eastern Pacific.............. 33,195 12 0 158,796 55 0
Northern Fur Seal.......................... California................... 22,098 10 0 106,298 47 0
Steller Sea Lion........................... Eastern...................... 999 3 0 5,346 13 0
Harbor Seal................................ California................... 71,463 261 1.00 391,189 1,642 7
Hawaiian Monk Seal......................... Hawaii....................... 1,104 6 0 7,380 25 0
Northern Elephant Seal..................... California Breeding.......... 118,514 111 0 626,540 645 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted
dolphin, and pygmy killer whales are not recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density
estimates were derived to support the Navy's analysis.

[[Page 32256]]

Table 55--Total Annual and 7-Year Incidental Take Proposed by Stock During All Activities by Effect Type
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Maximum 7-
Maximum Maximum Maximum annual non- Maximum Maximum 7- Maximum 7- Maximum 7- year non- Maximum 7-
Species Stock annual annual TTS annual AUD auditory annual year year TTS year AUD auditory year
behavioral INJ injury mortality behavioral INJ injury mortality
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale............................ Eastern North Pacific... 7,151 9,560 167 0 0.43 43,599 43,693 1,010 0 3
Gray Whale............................ Western North Pacific... 72 97 2 0 0 434 418 5 0 0
Blue Whale............................ Central North Pacific... 17 75 1 0 0 92 432 2 0 0
Blue Whale............................ Eastern North Pacific... 1,447 3,124 27 0 0.29 8,513 16,295 150 0 2
Bryde's Whale......................... Eastern Tropical Pacific 111 211 5 0 0 664 1,210 14 0 0
Bryde's Whale......................... Hawaii.................. 68 341 3 0 0 392 1,964 11 0 0
Fin Whale............................. Hawaii.................. 21 65 1 0 0 113 374 1 0 0
Fin Whale............................. California/Oregon/ 3,704 9,797 54 1 0.57 21,366 47,192 299 1 4
Washington.
Humpback Whale........................ Central America/Southern 547 1,341 19 0 0.29 3,305 6,593 96 0 2
Mexico-California/
Oregon/Washington.
Humpback Whale........................ Mainland Mexico- 1,274 3,175 43 1 0.29 7,701 15,669 219 1 2
California/Oregon/
Washington.
Humpback Whale........................ Hawaii.................. 1227 1,807 24 0 0.43 7,828 11,117 151 0 3
Minke Whale........................... Hawaii.................. 44 252 3 0 0 259 1,439 13 0 0
Minke Whale........................... California/Oregon/ 942 2,051 32 0 0 5,735 10,381 193 0 0
Washington.
Sei Whale............................. Hawaii.................. 38 215 2 0 0 227 1,210 5 0 0
Sei Whale............................. Eastern North Pacific... 83 219 3 0 0.29 487 1,124 9 0 2
Sperm Whale........................... Hawaii.................. 1237 412 1 0 0.14 7,313 2,306 1 0 1
Sperm Whale........................... California/Oregon/ 2,999 892 3 0 0 16,304 4,302 5 0 0
Washington.
Dwarf Sperm Whale..................... Hawaii.................. 10,880 34,344 914 1 0 67,933 194,468 5,102 1 0
Dwarf Sperm Whale..................... California/Oregon/ 1,505 4,159 94 0 0 8,583 21,510 517 0 0
Washington.
Pygmy Sperm Whale..................... Hawaii.................. 10,954 34,833 935 1 0 68,237 197,085 5,220 1 0
Pygmy Sperm Whale..................... California/Oregon/ 1549 4,066 107 0 0 8,830 21,038 609 0 0
Washington.
Baird's Beaked Whale.................. California/Oregon/ 10,112 62 0 0 0 55,858 291 0 0 0
Washington.
Blainville's Beaked Whale............. Hawaii.................. 7,508 34 0 0 0 45,810 194 0 0 0
Goose-Beaked Whale.................... Hawaii.................. 30230 129 0 0 0 184,319 720 0 0 0
Goose-Beaked Whale.................... California/Oregon/ 166,204 612 2 0 0 936,000 3,012 4 0 0
Washington.
Longman's Beaked Whale................ Hawaii.................. 18,219 97 1 0 0 111,612 540 4 0 0
Mesoplodont Beaked Whale.............. California/Oregon/ 92,419 420 2 0 0 518,892 2,046 6 0 0
Washington.
False Killer Whale.................... Main Hawaiian Islands 105 64 0 0 0 637 372 0 0 0
Insular.
False Killer Whale.................... Northwest Hawaiian 128 63 0 0 0 775 390 0 0 0
Islands.
False Killer Whale.................... Hawaii Pelagic.......... 936 734 1 0 0 5,719 4,146 1 0 0
False Killer Whale.................... Baja California 1,710 827 2 0 0 9,540 4,348 2 0 0
Peninsula Mexico *.
Killer Whale.......................... Hawaii.................. 57 70 0 0 0 337 396 0 0 0
Killer Whale.......................... Eastern North Pacific 830 193 4 0 0 5,053 1,036 23 0 0
Offshore.
Killer Whale.......................... West Coast Transient.... 27 28 0 0 0 137 124 0 0 0
Melon-Headed Whale.................... Hawaiian Islands........ 16187 15,269 13 0 0 98,220 85,553 68 0 0
Melon-Headed Whale.................... Kohala Resident (Hawaii) 41 15 0 0 0 250 82 0 0 0
Pygmy Killer Whale.................... Hawaii.................. 4,654 4,241 3 0 0 28,302 23,757 8 0 0
Pygmy Killer Whale.................... California-Baja 622 173 0 0 0 3,499 859 0 0 0
California Peninsula
Mexico *.
Short-Finned Pilot Whale.............. Hawaii.................. 11626 5,678 6 1 0 72,315 32,457 25 1 0
Short-Finned Pilot Whale.............. California/Oregon/ 3,353 926 9 2 0.57 19,691 4,841 44 12 4
Washington.
Bottlenose Dolphin.................... Maui Nui................ 309 17 0 0 0 2,049 102 0 0 0
Bottlenose Dolphin.................... Hawaii Island........... 5 4 0 0 0 27 17 0 0 0
Bottlenose Dolphin.................... Hawaii Pelagic.......... 37284 6,029 23 2 0.29 251,065 36,054 151 12 2
Bottlenose Dolphin.................... Kaua[revaps]i/ 1,221 239 0 0 0 7,657 1,657 0 0 0
Ni[revaps]ihau.
Bottlenose Dolphin.................... O[revaps]ahu............ 7,108 124 5 1 0.14 49,565 810 27 3 1
Bottlenose Dolphin.................... California Coastal...... 1,306 44 6 1 0 8,502 259 41 1 0
Bottlenose Dolphin.................... California/Oregon/ 21232 6,826 14 1 0 122,030 35,598 80 3 0
Washington Offshore.
Fraser's Dolphin...................... Hawaii.................. 19,854 15,626 6 2 0 122,248 88,278 32 2 0
Long-Beaked Common Dolphin............ California.............. 253,952 42,926 128 24 2.43 1,588,795 215,998 804 148 17
Northern Right Whale Dolphin.......... California/Oregon/ 23867 21,647 19 2 0.14 125,984 98,055 90 6 1
Washington.
Pacific White-Sided Dolphin........... California/Oregon/ 45,571 23,639 38 4 0.29 254,280 106,769 218 24 2
Washington.
Pantropical Spotted Dolphin........... Maui Nui................ 2,191 182 4 0 0 14,107 1,085 18 0 0
Pantropical Spotted Dolphin........... Hawaii Island........... 2902 3,122 6 1 0 17,820 17,764 23 2 0

[[Page 32257]]

Pantropical Spotted Dolphin........... Hawaii Pelagic.......... 24231 20,159 16 3 0 148,329 113,826 77 4 0
Pantropical Spotted Dolphin........... O'ahu................... 6,255 171 5 1 0 43,081 1,119 22 1 0
Pantropical Spotted Dolphin........... Baja California 60,809 36,817 45 2 0.29 341,397 194,284 232 7 2
Peninsula Mexico*.
Risso's Dolphin....................... Hawaii.................. 3,564 2,994 4 0 0 21,364 16,676 5 0 0
Risso's Dolphin....................... California/Oregon/ 33,191 10,642 17 4 0 188,061 52,786 107 18 0
Washington.
Rough-Toothed Dolphin................. Hawaii.................. 57947 38,926 31 5 0.29 367,021 220,798 175 21 2
Short-Beaked Common Dolphin........... California/Oregon/ 1,499,861 669,693 806 71 15.29 8,473,412 3,331,011 4,634 441 107
Washington.
Spinner Dolphin....................... Hawaii Pelagic.......... 2,177 2,367 2 0 0 13,145 13,394 4 0 0
Spinner Dolphin....................... Hawaii Island........... 60 50 1 0 0 362 282 1 0 0
Spinner Dolphin....................... Kaua[revaps]i/ 3,561 885 2 0 0 22,186 6,148 6 0 0
Ni[revaps]ihau.
Spinner Dolphin....................... O[revaps]ahu/4 Islands 1,156 45 1 0 0 7,942 263 2 0 0
Region.
Striped Dolphin....................... Hawaii Pelagic.......... 18,620 19162 10 2 0 112,710 106,884 48 4 0
Striped Dolphin....................... California/Oregon/ 81,046 52,353 42 2 0.14 453,209 270,965 222 9 1
Washington.
Dall's Porpoise....................... California/Oregon/ 13,394 46,225 1,235 2 0 76,921 228,511 6,781 5 0
Washington.
Harbor Porpoise....................... Monterey Bay............ 2,179 0 0 0 0 10,934 0 0 0 0
Harbor Porpoise....................... Morro Bay............... 4,152 221 87 1 0 24,909 1,407 588 2 0
Harbor Porpoise....................... Northern California/ 481 0 0 0 0 2,339 0 0 0 0
Southern Oregon.
Harbor Porpoise....................... San Francisco/Russian 9,898 62 26 0 0 48,554 346 169 0 0
River.
California Sea Lion................... U.S..................... 1,638,285 261464 666 57 3.86 9,421,167 1,206,972 4,203 369 27
Guadalupe Fur Seal.................... Mexico.................. 266199 81,354 51 3 0.14 1,491,214 409,620 284 16 1
Northern Fur Seal..................... Eastern Pacific......... 23105 10,090 11 1 0 114,217 44,579 53 2 0
Northern Fur Seal..................... California.............. 15853 6,245 9 1 0 78,553 27,745 44 3 0
Steller Sea Lion...................... Eastern................. 837 162 3 0 0 4,601 745 13 0 0
Harbor Seal........................... California.............. 52,154 19,309 254 7 1.00 286,337 104,852 1,598 44 7
Hawaiian Monk Seal.................... Hawaii.................. 906 198 5 1 0 6,149 1231 24 1 0
Northern Elephant Seal................ California Breeding..... 65,095 53,419 109 2 0 379,380 247,160 643 2 0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Zero (0) impacts indicate total less than 0.5 and a dash (-) is a true zero. In some cases where the estimated take within a cell is equal to 1, that value has been rounded up from a
value that is less than 0.5 to avoid underestimating potential impacts to a species or stock based on the 7-year rounding rules discussed in section 2.4 of appendix E (Explosive and Acoustic
Analysis Report) of the 2024 HCTT Draft EIS/OEIS.
* The Baja California Peninsula Mexico and California--Baja California Peninsula Mexico populations of false killer whale, pantropical spotted dolphin, and pygmy killer whales are not
recognized stocks in NMFS Pacific stock assessment report (Carretta et al., 2024), but separate density estimates were derived to support the Navy's analysis.

[[Page 32258]]

Proposed Mitigation Measures

Under section 101(a)(5)(A) of the MMPA, NMFS must set forth the
permissible methods of taking pursuant to the activity, and other means
of effecting the least practicable adverse impact on the species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance, and on the
availability of the species or stocks for subsistence uses (``least
practicable adverse impact''). NMFS does not have a regulatory
definition for least practicable adverse impact. The 2004 NDAA amended
the MMPA as it relates to military readiness activities and the
incidental take authorization process such that a determination of
``least practicable adverse impact'' shall include consideration of
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity. For additional
discussion of NMFS' interpretation of the least practicable adverse
impact standard, see the Mitigation Measures section of the Gulf of
Alaska Study Area final rule (88 FR 604, January 4, 2023).

Implementation of Least Practicable Adverse Impact Standard

Here, we discuss how we determine whether a measure or set of
measures meets the ``least practicable adverse impact'' standard. Our
separate analysis of whether the take anticipated to result from the
Action Proponents' activities meets the ``negligible impact'' standard
appears in the Preliminary Analysis and Negligible Impact Determination
section below.
Our evaluation of potential mitigation measures includes
consideration of two primary factors: (1) The manner in which, and the
degree to which, implementation of the potential measure(s) is expected
to reduce adverse impacts to marine mammal species or stocks, their
habitat, or their availability for subsistence uses (where relevant).
This analysis considers such things as the nature of the potential
adverse impact (e.g., likelihood, scope, and range), the likelihood
that the measure will be effective if implemented, and the likelihood
of successful implementation. (2) The practicability of the measure(s)
for applicant implementation. Practicability of implementation may
consider such things as cost, impact on activities, and, in the case of
a military readiness activity, specifically considers personnel safety,
practicality of implementation, and impact on the effectiveness of the
military readiness activity.
While the language of the least practicable adverse impact standard
calls for minimizing impacts to affected species or stocks, we
recognize that the reduction of impacts to those species or stocks
accrues through the application of mitigation measures that limit
impacts to individual animals. Accordingly, NMFS' analysis focuses on
measures that are designed to avoid or minimize impacts on individual
marine mammals that are more likely to increase the probability or
severity of population-level effects.
While direct evidence of impacts to species or stocks from a
specified activity is rarely available, and additional study is still
needed to understand how specific disturbance events affect the fitness
of individuals of certain species, there have been improvements in
understanding the process by which disturbance effects are translated
to the population. With recent scientific advancements (both marine
mammal energetic research and the development of energetic frameworks),
the relative likelihood or degree of impacts on species or stocks may
often be inferred given a detailed understanding of the activity, the
environment, and the affected species or stocks--and the best available
science has been used here. This same information is used in the
development of mitigation measures and helps us understand how
mitigation measures contribute to lessening effects (or the risk
thereof) to species or stocks. We also acknowledge that there is always
the potential that new information, or a new recommendation, could
become available in the future and necessitate reevaluation of
mitigation measures (which may be addressed through adaptive
management) to see if further reductions of population impacts are
possible and practicable.
In the evaluation of specific measures, the details of the
specified activity will necessarily inform each of the two primary
factors discussed above (expected reduction of impacts and
practicability) and are carefully considered to determine the types of
mitigation that are appropriate under the least practicable adverse
impact standard. Analysis of how a potential mitigation measure may
reduce adverse impacts on a marine mammal stock or species,
consideration of personnel safety, practicality of implementation, and
consideration of the impact on effectiveness of military readiness
activities are not issues that can be meaningfully evaluated through a
yes/no lens. The manner in which, and the degree to which,
implementation of a measure is expected to reduce impacts, as well as
its practicability in terms of these considerations, can vary widely.
For example, a time/area restriction could be of very high value for
decreasing population-level impacts (e.g., avoiding disturbance of
feeding females in an area of established biological importance) or it
could be of lower value (e.g., decreased disturbance in an area of high
productivity but of less biological importance). Regarding
practicability, a measure might involve restrictions in an area or time
that impede the Navy's ability to certify a strike group (higher impact
on mission effectiveness), or it could mean delaying a small in-port
training event by 30 minutes to avoid exposure of a marine mammal to
injurious levels of sound (i.e., lower impact). A responsible
evaluation of ``least practicable adverse impact'' will consider the
factors along these realistic scales. Accordingly, the greater the
likelihood that a measure will contribute to reducing the probability
or severity of adverse impacts to the species or stock or its habitat,
the greater the weight that measure is given when considered in
combination with practicability to determine the appropriateness of the
mitigation measure, and vice versa. We discuss consideration of these
factors in greater detail below.
1. Reduction of adverse impacts to marine mammal species or stocks
and their habitat.
The emphasis given to a measure's ability to reduce the impacts on
a species or stock considers the degree, likelihood, and context of the
anticipated reduction of impacts to individuals (and how many
individuals) as well as the status of the species or stock.
The ultimate impact on any individual from a disturbance event
(which informs the likelihood of adverse species- or stock-level
effects) is dependent on the circumstances and associated contextual
factors, such as duration of exposure to stressors. Though any proposed
mitigation needs to be evaluated in the context of the specific
activity and the species or stocks affected, measures with the
following types of effects have greater value in reducing the
likelihood or severity of adverse species- or stock-level impacts:
avoiding or minimizing injury or mortality; limiting interruption of
known feeding, breeding, mother/young, or resting behaviors; minimizing
the abandonment of important habitat (temporally and spatially);
minimizing the number of individuals subjected to these types of
disruptions; and limiting

[[Page 32259]]

degradation of habitat. Mitigating these types of effects is intended
to reduce the likelihood that the activity will result in energetic or
other types of impacts that are more likely to result in reduced
reproductive success or survivorship. It is also important to consider
the degree of impacts that are expected in the absence of mitigation in
order to assess the added value of any potential measures. Finally,
because the least practicable adverse impact standard gives NMFS
discretion to weigh a variety of factors when determining appropriate
mitigation measures and because the focus of the standard is on
reducing impacts at the species or stock level, the least practicable
adverse impact standard does not compel mitigation for every kind of
take, or every individual taken, if that mitigation is unlikely to
meaningfully contribute to the reduction of adverse impacts on the
species or stock and its habitat, even when practicable for
implementation by the applicant.
The status of the species or stock is also relevant in evaluating
the appropriateness of potential mitigation measures in the context of
least practicable adverse impact. The following are examples of factors
that may, alone or in combination, result in greater emphasis on the
importance of a mitigation measure in reducing impacts on a species or
stock: the stock is known to be decreasing or status is unknown, but
believed to be declining; the known annual mortality (from any source)
is approaching or exceeding the PBR level (as defined in MMPA section
3(20)); the affected species or stock is a small, resident population;
or the stock is involved in a UME or has other known vulnerabilities
(e.g., recovering from an oil spill).
Habitat mitigation, particularly as it relates to rookeries, mating
grounds, and areas of similar significance, is also relevant to
achieving the standard and can include measures such as reducing
impacts of the activity on known prey utilized in the activity area or
reducing impacts on physical habitat. As with species- or stock-related
mitigation, the emphasis given to a measure's ability to reduce impacts
on a species or stock's habitat considers the degree, likelihood, and
context of the anticipated reduction of impacts to habitat. Because
habitat value is informed by marine mammal presence and use, in some
cases there may be overlap in measures for the species or stock and for
use of habitat.
We consider available information indicating the likelihood of any
measure to accomplish its objective. If evidence shows that a measure
has not typically been effective nor successful, then either that
measure should be modified or the potential value of the measure to
reduce effects should be lowered.
2. Practicability.
Factors considered may include cost, impact on activities, and, in
the case of a military readiness activity, will include personnel
safety, practicality of implementation, and impact on the effectiveness
of the military readiness activity (see 16 U.S.C. 1371(a)(5)(A)(iii)).

Assessment of Mitigation Measures for the HCTT Study Area

NMFS has fully reviewed the specified activities and the mitigation
measures included in the application and the 2024 HCTT Draft EIS/OEIS
to determine if the mitigation measures would result in the least
practicable adverse impact on marine mammals and their habitat. NMFS
worked with the Action Proponents in the development of their initially
proposed measures, which are informed by years of implementation and
monitoring. A complete discussion of the Action Proponents' evaluation
process used to develop, assess, and select mitigation measures, which
was informed by input from NMFS, can be found in chapter 5 (Mitigation)
and appendix K (Geographic Mitigation Assessment) of the 2024 HCTT
Draft EIS/OEIS. The process described in chapter 5 (Mitigation) and
appendix A (Activity Descriptions) of the 2024 HCTT Draft EIS/OEIS
robustly supported NMFS' independent evaluation of whether the
mitigation measures would meet the least practicable adverse impact
standard. The Action Proponents would be required to implement the
mitigation measures identified in this proposed rule for the full 7
years to avoid or reduce potential impacts from acoustic, explosive,
and physical disturbance and strike stressors.
As a general matter, where an applicant proposes measures that are
likely to reduce impacts to marine mammals, the fact that they are
included in the application indicates that the measures are
practicable, and it is not necessary for NMFS to conduct a detailed
analysis of the measures the applicant proposed (rather, they are
simply included). However, it is still necessary for NMFS to consider
whether there are additional practicable measures that would
meaningfully reduce the probability or severity of impacts that could
affect reproductive success or survivorship.
The Action Proponents have agreed to mitigation measures that would
reduce the probability and/or severity of impacts expected to result
from acute exposure to acoustic sources or explosives, vessel strike,
and impacts to marine mammal habitat. Specifically, the Action
Proponents would use a combination of delayed starts, powerdowns, and
shutdowns to avoid mortality or serious injury, minimize the likelihood
or severity of AUD INJ or non-auditory injury, and reduce instances of
TTS or more severe behavioral disturbance caused by acoustic sources or
explosives. The Action Proponents would also implement multiple time/
area restrictions that would reduce take of marine mammals in areas or
at times where they are known to engage in important behaviors (e.g.,
calving, where the disruption of those behaviors would have a higher
probability of resulting in impacts on reproduction or survival of
individuals that could lead to population-level impacts.
The Action Proponents assessed the practicability of the proposed
measures in the context of personnel safety, practicality of
implementation, and their impacts on the Action Proponents' ability to
meet their Congressionally mandated requirements and found that the
measures are supportable. As described in more detail below, NMFS has
independently evaluated the measures the Action Proponents proposed in
the manner described earlier in this section (i.e., in consideration of
their ability to reduce adverse impacts on marine mammal species and
their habitat and their practicability for implementation). We have
determined that the measures would significantly reduce impacts on the
affected marine mammal species and stocks and their habitat and,
further, be practicable for implementation by the Action Proponents. We
have preliminarily determined that the mitigation measures assure that
the Action Proponents' activities would have the least practicable
adverse impact on the species or stocks and their habitat.
The Action Proponents also evaluated numerous measures in the 2024
HCTT Draft EIS/OEIS that were not included in the application, and NMFS
independently reviewed and preliminarily concurs with the Action
Proponents' analysis that their inclusion was not appropriate under the
least practicable adverse impact standard based on our assessment. The
Action Proponents considered these additional potential mitigation
measures in the context of the potential benefits to marine mammals and
whether they are practical or impractical.
Section 5.9 (Measures Considered but Eliminated) of chapter 5
(Mitigation) of the 2024 HCTT Draft EIS/OEIS, includes

[[Page 32260]]

an analysis of an array of different types of mitigation that have been
recommended over the years by non-governmental organizations or the
public, through scoping or public comment on environmental compliance
documents. These recommendations generally fall into three categories,
discussed below: reduction of activity; activity-based operational
measures; and time/area limitations.
As described in section 5.9 (Measures Considered but Eliminated) of
the 2024 HCTT Draft EIS/OEIS, the Action Proponents considered reducing
the overall amount of training, reducing explosive use, modifying sound
sources, completely replacing live training with computer simulation,
and including time of day restrictions. Many of these mitigation
measures could potentially reduce the number of marine mammals taken
via direct reduction of the activities or amount of sound energy put in
the water. However, as described in chapter 5 (Mitigation) of the 2024
HCTT Draft EIS/OEIS, the Action Proponents need to train in the
conditions in which they fight--and these types of modifications
fundamentally change the activity in a manner that would not support
the purpose and need for the training (i.e., are entirely
impracticable) and therefore are not considered further. NMFS finds the
Action Proponents' explanation of why adoption of these recommendations
would unacceptably undermine the purpose of the training persuasive.
After independent review, NMFS finds the Action Proponents' judgment on
the impacts of these potential mitigation measures to personnel safety,
practicality of implementation, and the effectiveness of training
persuasive, and for these reasons, NMFS finds that these measures do
not meet the least practicable adverse impact standard because they are
not practicable.
In chapter 5 (Mitigation) of the 2024 HCTT Draft EIS/OEIS, the
Action Proponents also evaluated additional potential activity--based
mitigation measures, including increased mitigation zones, ramp-up
measures, additional passive acoustic and visual monitoring, and
decreased vessel speeds. Some of these measures have the potential to
incrementally reduce take to some degree in certain circumstances,
though the degree to which this would occur is typically low or
uncertain. However, as described in the Action Proponents' analysis,
the measures would have significant direct negative effects on mission
effectiveness and are considered impracticable. NMFS independently
reviewed the Action Proponents' evaluation and concurs with this
assessment, which supports NMFS' preliminary findings that the
impracticability of this additional mitigation would greatly outweigh
any potential minor reduction in marine mammal impacts that might
result; therefore, these additional mitigation measures are not
warranted.
Lastly, chapter 5 (Mitigation) of the 2024 HCTT Draft EIS/OEIS also
describes a comprehensive analysis of potential geographic mitigation
that includes consideration of both a biological assessment of how the
potential time/area limitation would benefit the species and its
habitat (e.g., is a key area of biological importance or would result
in avoidance or reduction of impacts) in the context of the stressors
of concern in the specific area and an operational assessment of the
practicability of implementation (e.g., including an assessment of the
specific importance of an area for training, considering proximity to
training ranges and emergency landing fields and other issues). In some
cases, potential benefits to marine mammals were non-existent, while in
others the consequences on mission effectiveness were too great.
NMFS has reviewed the Action Proponents' analysis in chapter 5
(Mitigation) and appendix A (Activity Descriptions) of the 2024 HCTT
Draft EIS/OEIS, which consider the same factors that NMFS considers to
satisfy the least practicable adverse impact standard, and concurs with
the analysis and conclusions. Therefore, NMFS is not proposing to
include any of the measures that the Action Proponents ruled out in the
2024 HCTT Draft EIS/OEIS. Below are the mitigation measures that NMFS
has preliminarily determined would ensure the least practicable adverse
impact on all affected species and their habitat, including the
specific considerations for military readiness activities. Table 56
describes the information designed to aid Lookouts and other applicable
personnel with their observation, environmental compliance, and
reporting responsibilities. The following sections describe the
mitigation measures that would be implemented in association with the
activities analyzed in this document. The mitigation measures are
organized into two categories: activity-based mitigation and geographic
mitigation areas.
Of note, according to the U.S. Navy, consistent with customary
international law, when a foreign military vessel participates in a
U.S. Navy exercise within the U.S. territorial sea (i.e., 0 to 12 nmi
(0 to 22.2 km) from shore), the U.S. Navy will request that the foreign
vessel follow the U.S. Navy's mitigation measures for that particular
event. When a foreign military vessel participates in a U.S. Navy
exercise beyond the U.S. territorial sea but within the U.S. Exclusive
Economic Zone, the U.S. Navy will encourage the foreign vessel to
follow the U.S. Navy's mitigation measures for that particular event
(Navy 2022a; Navy 2022b). In either scenario (i.e., both within and
beyond the territorial sea), U.S. Navy personnel will provide the
foreign vessels participating with a description of the mitigation
measures to follow.

Table 56--Environmental Awareness and Education
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: All training and testing activities, as
applicable.
------------------------------------------------------------------------
Requirements: Navy personnel (including civilian personnel) involved in
mitigation and training or testing activity reporting under the
specified activities must complete one or more modules of the U.S. Navy
Afloat Environmental Compliance Training Series, as identified in their
career path training plan. Modules include:
Introduction to Afloat Environmental Compliance Training
Series. The introductory module provides information on
environmental laws (e.g., ESA, MMPA) and the corresponding
responsibilities that are relevant to military readiness
activities. The material explains why environmental compliance is
important in supporting the Action Proponents' commitment to
environmental stewardship.
Marine Species Awareness Training. All bridge watch
personnel, Commanding Officers, Executive Officers, maritime patrol
aircraft aircrews, anti[hyphen]submarine warfare and mine warfare
rotary-wing aircrews, Lookouts, and equivalent civilian personnel
must successfully complete the Marine Species Awareness Training
prior to standing watch or serving as a Lookout. The Marine Species
Awareness Training provides information on sighting cues, visual
observation tools and techniques, and sighting notification
procedures. Navy biologists developed Marine Species Awareness
Training to improve the effectiveness of visual observations for
biological resources, focusing on marine mammals and sea turtles,
and including floating vegetation, jellyfish aggregations, and
flocks of seabirds.
Protective Measures Assessment Protocol. This module
provides the necessary instruction for accessing mitigation
requirements during the event planning phase using the Protective
Measures Assessment Protocol (PMAP) software tool.

[[Page 32261]]

Sonar Positional Reporting System and Marine Mammal
Incident Reporting. This module provides instruction on the
procedures and activity reporting requirements for the Sonar
Positional Reporting System and marine mammal incident reporting.
------------------------------------------------------------------------

Activity-Based Mitigation

Activity-based mitigation is mitigation that the Action Proponents
would implement whenever and wherever an applicable military readiness
activity takes place within the HCTT Study Area. Previously referred to
as ``Procedural Mitigation,'' the primary objective of activity-based
mitigation is to reduce overlap of marine mammals with stressors that
have the potential to cause injury or mortality in real time. Activity-
based mitigations are fundamentally consistent across stressor
activity, although specific variations account for differences in
platform configuration, event characteristics, and stressor types. The
Action Proponents customize mitigation for each applicable activity
category or stressor. Activity-based mitigation generally involves: (1)
the use of one or more trained Lookouts to diligently observe for
marine mammals and other specific biological resources (e.g., indicator
species like floating vegetation, jelly aggregations, large schools of
fish, and flocks of seabirds) within a mitigation zone; (2)
requirements for Lookouts to immediately communicate sightings of
marine mammals and other specific biological resources to the
appropriate watch station for information dissemination; and (3)
requirements for the watch station to implement mitigation (e.g., halt
an activity) until certain recommencement conditions have been met. The
remainder of the mitigation measures are activity-based mitigation
measures (table 57 through table 76) organized by stressor type and
activity category and include acoustic stressors (i.e., active sonar,
air guns, pile driving, weapons firing noise), explosive stressors
(i.e., bombs, gunnery, underwater demolition, mine counter-measure and
neutralization activities, missiles and rockets, sonobuoys and
research-based sub-surface explosives, ship shock trials, and sinking
exercises), and physical disturbance and strike stressors (i.e.,
aerial-deployed mines and non-explosive bombs, non-explosive gunnery,
non-explosive torpedoes missiles and rockets, vessel movement, towed
in-water devices, and net deployment).
The Action Proponents must implement the proposed mitigation
measures described in table 57 through table 76, as appropriate, in
response to an applicable sighting within, or entering into, the
relevant mitigation zone for acoustic stressors, explosives, and non-
explosive munitions. Each table describes the activities that the
requirements apply to, the required mitigation zones in which the
action proponents must take a mitigation action, the required number of
Lookouts and observation platform, the required mitigation actions that
the action proponents must take before, during, and/or after an
activity, and a required wait period prior to commencing or
recommencing an activity after a delay, power down, or shutdown of an
activity.
The Action Proponents proposed wait periods because events cannot
be delayed or ceased indefinitely for the purpose of mitigation due to
impacts on safety, sustainability, and the ability to meet mission
requirements. Wait periods are designed to allow animals the maximum
amount of time practical to resurface (i.e., become available to be
observed) before activities resume. The action proponents factored in
an assumption that mitigation may need to be implemented more than once
when developing wait period durations. Wait periods are 10 minutes, 15
minutes, or 30 minutes depending on the fuel constraints of the
platform and feasibility of implementation. NMFS concurs with these
proposed wait periods.
If an applicable species (identified in the relevant mitigation
tables) is observed within a required mitigation zone prior to the
initial start of the activity, the Action Proponents must: (1) relocate
the event to a location where applicable species are not observed; or
(2) delay the initial start of the event (or stressor use) until one of
the ``Mitigation Zone All-Clear Conditions'' (defined below) has been
met. If an applicable stressor is observed within a required mitigation
zone during the event (i.e., during use of the indicated source) the
Action Proponents must take the action described in the ``Mitigation
Zones'' section of the table until one of the Mitigation Zone All-Clear
Conditions has been met.
For all activities, an activity may not commence or recommence
until one of the following ``Mitigation Zone All-Clear Conditions''
have been met: (1) a Lookout observes the applicable species exiting
the mitigation zone; (2) a Lookout concludes that the animal has exited
the mitigation zone based on its observed course, speed, and movement
relative to the mitigation zone; (3) a Lookout affirms the mitigation
zone has been clear from additional sightings for a designated ``wait
period''; or (4) for mobile events, the stressor has transited a
distance equal to double the mitigation zone size beyond the location
of the last sighting.
Activity-Based Mitigation for Active Acoustic Stressors
Mitigation measures for acoustic stressors are provided below and
include active acoustic sources (table 57), pile driving and extraction
(table 58), and weapons firing noise (table 59). For this proposed
action, the following ranges apply to the use of small, medium, and
large caliber: small is up to and including 50 caliber machine gun
rounds; medium is greater than 50 caliber and less than 57 millimeter
(mm; 2.24 inch); and large is 57 mm (2.24 inch) and larger. Small
caliber items are solid projectiles (i.e., bullets). Medium caliber
items are 30-57 mm (1.18-2.24 inch) and can have both inert non-
explosive rounds and high explosive rounds. High caliber items are
greater than or equal to 57 mm (2.24 inch) and can have both inert non-
explosive rounds and high explosive rounds. Activity-based mitigation
for acoustic stressors does not apply to:
sources not operated under positive control (e.g., moored
oceanographic sources);
sources used for safety of navigation (e.g., fathometers);
sources used or deployed by aircraft operating at high
altitudes (e.g., bombs deployed from high altitude (since personnel
cannot effectively observe the surface of the water));
sources used, deployed, or towed by unmanned platforms
except when escort vessels are already participating in the event and
have positive control over the source;
sources used by submerged submarines (e.g., sonar (since
they cannot conduct visual observation));
de minimis sources (e.g., those >200 kHz); and
vessel-based, unmanned vehicle-based, or towed in-water
sources when marine mammals (e.g., dolphins) are determined to be
intentionally swimming at the bow or alongside or

[[Page 32262]]

directly behind the vessel, vehicle, or device (e.g., to bow-ride or
wake-ride).

Table 57--Mitigation for Active Acoustic Sources
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Active acoustic sources with power down and shut
down capabilities:
Low-frequency active sonar >=200 dB.
Mid-frequency active sonar sources that are hull mounted on
a surface ship (including surfaced submarines).
Broadband and other active acoustic sources >200 dB.
------------------------------------------------------------------------
Mitigation Zones:
[cir] 1,000 yd (914.4 m) from active acoustic sources (power
down of 6 dB total).
[cir] 500 yd (457.2 m) from active acoustic sources (power down
of 10 dB total).
[cir] 200 yd (182.9 m) from active acoustic sources (shut down).
Mitigation Requirements:
[cir] One Lookout in/on one of the following:
[ssquf] Aircraft.
[ssquf] Pierside, moored, or anchored vessel
[ssquf] Underway vessel with space/crew restrictions
(including small boats).
[ssquf] Underway vessel already participating in the event
that is escorting (and has positive control over sources
used, deployed, or towed by) an unmanned platform.
[cir] Two Lookouts on an underway vessel without space/crew
restrictions.
[cir] Lookouts would use information from passive acoustic
detections to inform visual observations when passive acoustic
devices are already being used in the event.
Mitigation Requirement Timing:
[cir] Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation
immediately prior to the initial start of using active acoustic
sources (e.g., while maneuvering on station).
[cir] Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during use of active
acoustic sources.
Wait Period:
[cir] 10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------
Stressor or Activity: Active acoustic sources with shut down (but not
power down) capabilities:
Low-frequency active sonar <200 dB.
Mid-frequency active sonar sources that are not hull
mounted on a surface ship (e.g., dipping sonar, towed arrays).
High-frequency active sonar.
Air guns.
Broadband and other active acoustic sources <200 dB.
------------------------------------------------------------------------
Mitigation Zones:
[cir] 200 yd (182.9 m) from active acoustic sources (shut down).
Mitigation Requirements:
One Lookout in/on one of the following:
Aircraft.
Pierside, moored, or anchored vessel.
Underway vessel with space/crew restrictions
(including small boats).
Underway vessel already participating in the event
that is escorting (and has positive control over sources
used, deployed, or towed by) an unmanned platform.
Two Lookouts on an underway vessel without space/crew
restrictions.
Lookouts would use information from passive acoustic
detections to inform visual observations when passive acoustic
devices are already being used in the event.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation immediately
prior to the initial start of using active acoustic sources
(e.g., while maneuvering on station).
Action Proponent personnel must observe the mitigation
zone for marine mammals during use of active acoustic sources.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 58--Mitigation for Pile Driving and Extraction
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Vibratory and impact pile driving and extraction.
------------------------------------------------------------------------
Mitigation Zone:
5 yd (4.6 m) from piles being driven or extracted
(cease pile driving or extraction).
Mitigation Requirements:
One Lookout on one of the following:
Shore.
Pier.
Small boat.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation for 15 minutes
prior to the initial start of pile driving or pile extraction.
Action Proponent personnel must observe the mitigation
zone for marine mammals during pile driving or extraction.
Wait Period:
15 minutes.
------------------------------------------------------------------------

[[Page 32263]]

Table 59--Mitigation for Weapons Firing Noise
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Explosive and non-explosive large-caliber gunnery
firing noise (surface-to-surface and surface-to-air).
------------------------------------------------------------------------
Mitigation Zone:
30 degrees on either side of the firing line out to 70
yd (64 m) from the gun muzzle (cease fire).
Mitigation Requirements:
One Lookout on a vessel.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation immediately
prior to the initial start of large-caliber gun firing (e.g.,
during target deployment).
Action Proponent personnel must observe the mitigation
zone for marine mammals during large-caliber gun firing.
Wait Period:
30 minutes.
------------------------------------------------------------------------

Activity-Based Mitigation for Explosive Stressors
Mitigation measures for explosive stressors are provided below and
include explosive bombs (table 60), explosive gunnery (table 61),
explosive underwater demolition multiple charge--mat weave and obstacle
loading (table 62), explosive mine countermeasure and neutralization
without divers (table 63), explosive mine neutralization with divers
(table 64), explosive missiles and rockets (table 65), explosive
sonobuoys and research-based sub-surface explosives (table 66),
explosive torpedoes (table 67), ship shock trials (table 68), and
SINKEX (table 69). After the event, the Action Proponents must observe
the area for marine mammals. Post-event observations are intended to
aid incident reporting requirements for marine mammals. Practicality
and the duration of post-event observations will be determined on site
by fuel restrictions and mission-essential follow-on commitments. For
example, it is more challenging to remain on-site for extended periods
of time for some activities due to factors such as range from the
target or altitude of an aircraft. For all activities involving
explosives, if a marine mammal is visibly injured or killed as a result
of detonation, explosives use in the event must be suspended
immediately. Activity-based mitigation for explosive stressors does not
apply to explosives:
deployed by aircraft operating at high altitudes;
deployed by submerged submarines, except for explosive
torpedoes;
deployed against aerial targets;
during vessel- or shore-launched missile or rocket events;
used at or below the de minimis threshold; and
deployed by unmanned platforms except when escort vessels
are already participating in the event and have positive control over
the explosive.

Table 60--Mitigation for Explosive Bombs
------------------------------------------------------------------------

Table 61--Mitigation for Explosive Gunnery
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Air-to-surface medium-caliber, surface-to-surface
medium-caliber, surface-to-surface large-caliber.
------------------------------------------------------------------------
Mitigation Zones:
Air-to-surface medium-caliber:
200 yd (182.9 m) from the intended impact location
(cease fire).
Surface-to-surface medium-caliber:
600 yd (548.6 m) from the intended impact location
(cease fire).
Surface-to-surface large-caliber:
1,000 yd (914.4 m) from the intended impact
location (cease fire).
Mitigation Requirements:
One Lookout on a vessel or in an aircraft.
Mitigation Requirement Timing:
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation
immediately prior to the initial start of gun firing (e.g.,
while maneuvering on station).
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during gunnery fire.

[[Page 32264]]

After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for injured or
dead marine mammals. If any injured or dead marine mammals are
observed, Action Proponent personnel must follow established
incident reporting procedures.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 62--Mitigation for Explosive Underwater Demolition Multiple
Charge--Mat Weave and Obstacle Loading
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Any NEW.
------------------------------------------------------------------------
Mitigation Zones:
700 yd (640 m) from the detonation site (cease fire).
Mitigation Requirements:
Two Lookouts: one on a small boat and one on shore from
an elevated platform.
Mitigation Requirement Timing:
The Lookout positioned on a small boat must observe the
mitigation zone for marine mammals and floating vegetation for
30 minutes prior to the first detonation.
The Lookout positioned onshore must use binoculars to
observe for marine mammals for 10 minutes prior to the first
detonation.
sbull; Action Proponent personnel must observe the mitigation
zone for marine mammals during detonations.
After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for 30 minutes
for marine mammals. If any injured or dead marine mammals are
observed, Action Proponent personnel must follow established
incident reporting procedures.
Wait Period:
10 minutes (determined by the shore observer).
------------------------------------------------------------------------

Table 63--Mitigation for Explosive Mine Countermeasure and
Neutralization
[No divers]
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: 0.1-5 lb (0.05-2.3 kg) NEW, >5 lb (2.3 kg) NEW.
------------------------------------------------------------------------
Mitigation Zones:
0.1-5 lb (0.05-2.3 kg) NEW:
600 yd (548.6 m) from the detonation site (cease
fire).
>5 lb (2.3 kg) NEW:
2,100 yd (1,920.2 m) from the detonation site
(cease fire).
Mitigation Requirements:
0.1-5 lb (0.05-2.3 kg) NEW:
One Lookout on a vessel or in an aircraft.
>5 lb (2.3 kg) NEW:
Two Lookouts: one on a small boat and one in an
aircraft.
Mitigation Requirement Timing:
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation
immediately prior to the initial start of detonations (e.g.,
while maneuvering on station; typically, 10 or 30 minutes
depending on fuel constraints).
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals, concentrations of seabirds,
and individual foraging seabirds (in the water and not on
shore) during detonations or fuse initiation.
After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for 10 or 30
minutes (depending on fuel constraints) for injured or dead
marine mammals. If any injured or dead marine mammals are
observed, Action Proponent personnel must follow established
incident reporting procedures.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 64--Mitigation for Explosive Mine Neutralization
[With divers]
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: 0.1-20 lb (0.05-9.1 kg) NEW (positive control),
0.1-29 lb (0.05-13.2 kg) NEW (time-delay), >20-60 lb (9.1-27.2 kg) NEW
(positive control).
------------------------------------------------------------------------
Mitigation Zones:
0.1-20 lb (0.05-9.1 kg) NEW (positive control).
500 yd (457.2 m) from the detonation site (cease
fire).
0.1-29 lb (0.05-13.2 kg) NEW (time-delay), >20-60 lb
(9.1-27.2 kg) NEW (positive control).
1,000 yd (914.4 m) from the detonation site (cease
fire).
Mitigation Requirements:
0.1-20 lb (0.05-9.1 kg) NEW (positive control).
Lookouts in two small boats (one Lookout per boat),
or one small boat and one rotary-wing aircraft (with one
Lookout each), and one Lookout on shore for shallow-water
events during 0.1-20 lb (0.05-9.1 kg) NEW (positive
control) use.
0.1-29 lb (0.05-13.2 kg) NEW (time-delay), >20-60 lb
(9.1-27.2 kg) NEW (positive control).
Four Lookouts in two small boats (two Lookouts per
boat), and one additional Lookout in an aircraft if used in
the event.
Mitigation Requirement Timing:

[[Page 32265]]

Time-delay devices must be set not to exceed 10
minutes.
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation
immediately prior to the initial start of detonations or fuse
initiation for positive control events (e.g., while maneuvering
on station) or for 30 minutes prior for time-delay events.
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals, concentrations of seabirds,
and individual foraging seabirds (in the water and not on
shore) during detonations or fuse initiation.
When practical based on mission, safety, and
environmental conditions:
Boats must observe from the mitigation zone radius
mid-point.
When two boats are used, boats must observe from
opposite sides of the mine location.
Platforms must travel a circular pattern around the
mine location.
Boats must have one Lookout observe inward toward
the mine location and one Lookout observe outward toward
the mitigation zone perimeter.
Divers must be part of the Lookout Team.
After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for 30 minutes
for injured or dead marine mammals. If any injured or dead
marine mammals are observed, Action Proponent personnel must
follow established incident reporting procedures.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 65--Mitigation for Explosive Missiles and Rockets
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: 0.6-20 lb (0.3-9.1 kg) NEW (air-to-surface), >20-
500 lb (9.1-226.8 kg) NEW (air-to-surface).
------------------------------------------------------------------------
Mitigation Zones:
0.6-20 lb (0.3-9.1 kg) NEW (air-to-surface).
900 yd (823 m) from the intended impact location
(cease fire).
>20-500 lb (9.1-226.8 kg) NEW (air-to-surface).
2,000 yd (1,828.8 m) from the intended impact
location (cease fire).
Mitigation Requirements:
One Lookout in an aircraft.
Mitigation Requirement Timing:
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation
immediately prior to the initial start of missile or rocket
delivery (e.g., during a fly-over of the mitigation zone).
Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during missile or rocket
delivery.
After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for injured or
dead marine mammals. If any injured or dead marine mammals are
observed, Action Proponent personnel must follow established
incident reporting procedures.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 66--Mitigation for Explosive Sonobuoys and Research-Based Sub-
Surface Explosives
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Any NEW of sonobuoys, 0.1-5 lb (0.05-2.3 kg) NEW
for other types of sub-surface explosives used in research
applications.
------------------------------------------------------------------------
Mitigation Zone:
600 yd (548.6 m) from the device or detonation sites
(cease fire).
Mitigation Requirements:
One Lookout on a small boat or in an aircraft.
Conduct passive acoustic monitoring for marine mammals;
use information from detections to assist visual observations.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation immediately
prior to the initial start of detonations (e.g., during
sonobuoy deployment, which typically lasts 20-30 minutes).
Action Proponent personnel must observe the mitigation
zone for marine mammals during detonations.
After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for injured or
dead marine mammals. If any injured or dead marine mammals are
observed, Action Proponent personnel must follow established
incident reporting procedures.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 67--Mitigation for Explosive Torpedoes
------------------------------------------------------------------------

[[Page 32266]]

Action Proponent personnel must observe the mitigation
zone for marine mammals, floating vegetation, and jellyfish
aggregations immediately prior to the initial start of
detonations (e.g., during target deployment).
Action Proponent personnel must observe the mitigation
zone for marine mammals during torpedo launches.
After the event, when practical, Action Proponent
personnel must observe the detonation vicinity for injured or
dead marine mammals. If any injured or dead marine mammals are
observed, Action Proponent personnel must follow established
incident reporting procedures.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 68--Mitigation for Ship Shock Trials
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Any NEW.
------------------------------------------------------------------------
Mitigation Zone:
3.5 nmi (6.5 km) from the target ship hull (cease
fire).
Mitigation Requirements:
On the day of the event, 10 observers (Lookouts and
third-party observers combined), spread between aircraft or
multiple vessels as specified in the event-specific mitigation
plan.
Mitigation Requirement Timing:
Action Proponent personnel must develop a detailed,
event-specific monitoring and mitigation plan in the year prior
to the event and provide it to NMFS for review.
Beginning at first light on days of detonation, until
the moment of detonation (as allowed by safety measures) Action
Proponent personnel must observe the mitigation zone for marine
mammals, floating vegetation, jellyfish aggregations, large
schools of fish, and flocks of seabirds.
If any dead or injured marine mammals are observed
after an individual detonation, Action Proponent personnel must
follow established incident reporting procedures and halt any
remaining detonations until Action Proponent personnel or third-
party observers can consult with NMFS and review or adapt the
event-specific mitigation plan, if necessary.
During the 2 days following the event (minimum) and up
to 7 days following the event (maximum), and as specified in
the event-specific mitigation plan, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals.
Wait Period:
30 minutes.
------------------------------------------------------------------------

Table 69--Mitigation for Sinking Exercises (SINKEX)
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Any NEW.
------------------------------------------------------------------------
Mitigation Zone:
2.5 nmi (4.6 km) from the target ship hull (cease
fire).
Mitigation Requirements:
Two Lookouts: one on a vessel and one in an aircraft.
Lookouts would use information from passive acoustic
detections to inform visual observations when passive acoustic
devices are already being used during weapon firing.
Mitigation Requirement Timing:
During aerial observations for 90 minutes prior to the
initial start of weapon firing, Action Proponent personnel must
observe the mitigation zone for marine mammals, floating
vegetation, and jellyfish aggregations.
From the vessel during weapon firing, and from the
aircraft and vessel immediately after planned or unplanned
breaks in weapon firing of more than 2 hours, Action Proponent
personnel must observe the mitigation zone for marine mammals.
Action Proponent personnel must observe the detonation
vicinity for injured or dead marine mammals for 2 hours after
sinking the vessel or until sunset, whichever comes first. If
any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
Wait Period:
30 minutes.
------------------------------------------------------------------------

Activity-Based Mitigation for Non-Explosive Ordnance
Mitigation measures for non-explosive ordnance are provided below
and include aerial-deployed mines and non-explosive bombs (table 70),
non-explosive gunnery (table 71), and non-explosive missiles and
rockets (table 72). Explosive aerial-deployed mines do not detonate
upon contact with the water surface and are therefore considered non-
explosive when mitigating the potential for a mine shape to strike a
marine mammal at the water surface. Activity-based mitigation for non-
explosive ordnance does not apply to non-explosive ordnance:
deployed by aircraft operating at high altitudes;
deployed against aerial targets and land-based targets;
deployed during vessel- or shore-launched missile or
rocket events; and
deployed by unmanned platforms except when escort vessels
are already participating in the event and have positive control over
ordnance deployment.

Table 70--Mitigation for Aerial-Deployed Mines and Non-Explosive Bombs
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Explosive aerial-deployed mines, non-explosive
aerial-deployed mines and non-explosive bombs.
------------------------------------------------------------------------
Mitigation Zone:

[[Page 32267]]

1,000 yd (914.4 m) from the intended target (cease
fire).
Mitigation Requirements:
One Lookout in an aircraft.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation immediately
prior to the initial start of mine or bomb delivery (e.g., when
arriving on station).
Action Proponent personnel must observe the mitigation
zone for marine mammals during mine or bomb delivery.
Wait Period:
10 minutes.
------------------------------------------------------------------------

Table 71--Mitigation for Non-Explosive Gunnery
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Non-explosive surface-to-surface large-caliber
ordnance, non-explosive surface-to-surface and air-to-surface medium-
caliber ordnance, non-explosive surface-to-surface and air-to-surface
small-caliber ordnance.
------------------------------------------------------------------------
Mitigation Zone:
200 yd (182.9 m) from the intended impact location
(cease fire).
Mitigation Requirements:
One Lookout on a vessel or in an aircraft.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation immediately
prior to the start of gun firing (e.g., while maneuvering on
station).
Action Proponent personnel must observe the mitigation
zone for marine mammals during gunnery firing.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Table 72--Mitigation for Non-Explosive Missiles and Rockets
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Non-explosives (air-to-surface).
------------------------------------------------------------------------
Mitigation Zone:
900 yd (823 m) from the intended impact location (cease
fire).
Mitigation Requirements:
One Lookout in an aircraft.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals and floating vegetation immediately
prior to the start of missile or rocket delivery (e.g., during
a fly-over of the mitigation zone).
Action Proponent personnel must observe the mitigation
zone for marine mammals during missile or rocket delivery.
Wait Period:
10 or 30 minutes (depending on fuel constraints of the
platform).
------------------------------------------------------------------------

Activity-Based Mitigation for Physical Disturbance and Strike Stressors
Mitigation measures for physical disturbance and strike stressors
are provided below and include crewed surface vessels (table 73),
unmanned vehicles (table 74), towed in-water devices (table 75), and
net deployment (table 76). Activity-based mitigation for physical
disturbance and strike stressors will not be implemented:
by submerged submarines;
by unmanned vehicles except when escort vessels are
already participating in the event and have positive control over the
unmanned vehicle movements;
when marine mammals (e.g., dolphins) are determined to be
intentionally swimming at the bow, alongside the vessel or vehicle, or
directly behind the vessel or vehicle (e.g., to bow-ride or wake-ride);
when pinnipeds are hauled out on man-made navigational
structures, port structures, and vessels;
by manned surface vessels and towed in-water devices
actively participating in cable laying during Modernization &
Sustainment of Ranges activities; and
when impractical based on mission requirements (e.g.,
during certain aspects of amphibious exercises).

Table 73--Mitigation for Manned Surface Vessels
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Manned surface vessels, including surfaced
submarines.
------------------------------------------------------------------------
Mitigation Zones:
Underway manned surface vessels must maneuver
themselves (which may include reducing speed) to maintain the
following distances as mission and circumstances allow:
500 yd (457.2 m) from whales.
200 yd (182.9 m) from other marine mammals.
Mitigation Requirements:
One or more Lookouts on manned underway surface vessels
in accordance with the most recent navigation safety
instruction.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals immediately prior to manned surface
vessels getting underway and while underway.
------------------------------------------------------------------------

[[Page 32268]]

Table 74--Mitigation for Unmanned Vehicles
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Unmanned Surface Vehicles and Unmanned Underwater
Vehicles already being escorted (and operated under positive control)
by a manned surface support vessel.
------------------------------------------------------------------------
Mitigation Zones:
A surface support vessel that is already participating
in the event, and has positive control over the unmanned
vehicle, must maneuver the unmanned vehicle (which may include
reducing its speed) to ensure it maintains the following
distances as mission and circumstances allow:
500 yd (457.2 m) from whales.
200 yd (182.9 m) from other marine mammals.
Mitigation Requirements:
One Lookout on a surface support vessel that is already
participating in the event and has positive control over the
unmanned vehicle.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals immediately prior to unmanned vehicles
getting underway and while underway.
------------------------------------------------------------------------

Table 75--Mitigation for Towed In-water Devices
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: In-water devices towed by an aircraft, a manned
surface vessel, or an Unmanned Surface Vehicle or Unmanned Underwater
Vehicle already being escorted (and operated under positive control) by
a manned surface vessel.
------------------------------------------------------------------------
Mitigation Zone:
Manned towing platforms, or surface support vessels
already participating in the event that have positive control
over an unmanned vehicle that is towing an in-water device,
must maneuver itself or the unmanned vehicle (which may include
reducing speed) to ensure towed in-water devices maintain the
following distances as mission and circumstances allow:
250 yd (228.6 m) from marine mammals.
Mitigation Requirements:
One Lookout on the manned towing vessel or aircraft, or
on a surface support vessel that is already participating in
the event and has positive control over an unmanned vehicle
that is towing an in-water device.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals immediately prior to and while in-water
devices are being towed.
------------------------------------------------------------------------

Table 76--Mitigation for Net Deployment
------------------------------------------------------------------------

-------------------------------------------------------------------------
Stressor or Activity: Nets deployed for testing of an Unmanned
Underwater Vehicle.
------------------------------------------------------------------------
Mitigation Zone:
If a marine mammal is sighted within 500 yd of the
deployment location, the support vessel must:
Delay deployment of nets until the mitigation zone
has been clear for 15 minutes.
Recover nets if they are deployed.
Mitigation Requirements:
One Lookout on the support vessel.
Mitigation Requirement Timing:
Action Proponent personnel must observe the mitigation
zone for marine mammals for 15 minutes prior to the deployment
of nets and while the nets are deployed.
Nets must be deployed during daylight hours only.
------------------------------------------------------------------------

Geographic Mitigation Areas
In addition to activity-based mitigation, the Action Proponents
would implement mitigation measures within mitigation areas to avoid or
minimize potential impacts on marine mammals (see figures 11-1 and 11-2
of the application). A full technical analysis of the mitigation areas
that the Action Proponents considered for marine mammals is provided in
appendix K (Geographic Mitigation Assessment) of the 2024 HCTT Draft
EIS/OEIS. The Action Proponents took into account public comments
received on the 2017 HSTT Draft EIS/OEIS, the best available science,
and the practicability of implementing additional mitigation measures
and has enhanced its mitigation areas and mitigation measures beyond
those that were included in the 2018-2025 regulations to further reduce
impacts to marine mammals.
Information on the mitigation measures that the Action Proponents
propose to implement within mitigation areas is provided in table 77
through table 86. The mitigation applies year-round unless specified
otherwise in the tables.
NMFS conducted an independent analysis of the mitigation areas that
the Action Proponent proposed, which are described below. NMFS
preliminarily concurs with the Action Proponents' analysis, which
indicates that the measures in these mitigation areas are both
practicable and will reduce the likelihood, magnitude, or severity of
adverse impacts to marine mammals or their habitat in the manner
described in the Action Proponents' analysis and this proposed rule.
NMFS is heavily reliant on the Action Proponents' description of
operational practicability, since the Action Proponents are best
equipped to describe the degree to which a given mitigation measure
affects personnel safety or mission effectiveness, and how practical it
is to implement. The Action Proponents consider the measures in this
proposed rule to be practicable, and NMFS concurs. We further discuss
the manner in which the Geographic Mitigation Areas in the proposed
rule will reduce the likelihood, magnitude,

[[Page 32269]]

or severity of adverse impacts to marine mammal species or their
habitat in the Preliminary Analysis and Negligible Impact Determination
section.
Geographic Mitigation Areas in Hawaii
Table 77 details geographic mitigation related to the use of active
sonar and explosives off Hawaii Island. The mitigation is a
continuation from Phase III.

Table 77--Hawaii Island Marine Mammal Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic........................... The Action Proponents must not use Mitigation in this area is designed
more than 300 hours of MF1 surface to reduce exposure of numerous
ship hull-mounted mid-frequency small and resident marine mammal
active sonar or 20 hours of populations (including Blainville's
helicopter dipping sonar (a mid- beaked whales, bottlenose dolphins,
frequency active sonar source) goose-beaked whales, dwarf sperm
annually within the mitigation area. whales, false killer whales, melon-
headed whales, pantropical spotted
dolphins, pygmy killer whales,
rough-toothed dolphins, short-
finned pilot whales, and spinner
dolphins), humpback whales within
important seasonal reproductive
habitat, and Hawaiian monk seals
within critical habitat, to levels
of sound that have the potential to
cause injurious or behavioral
impacts.
Explosives......................... The Action Proponents must not Mitigation in this area is designed
detonate in-water explosives to prevent exposure of the species
(including underwater explosives and listed above to explosives that
explosives deployed against surface have the potential to cause injury,
targets) within the mitigation area. mortality, or behavioral
disturbance.
----------------------------------------------------------------------------------------------------------------

Table 78 details geographic mitigation related to the use of active
sonar and explosives off Moloka[revaps]i, Maui, L[amacr]na[revaps]i,
and Kaho[revaps]olawe Islands. The mitigation is a continuation from
Phase III.

Table 78--Hawaii 4-Islands Marine Mammal Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic........................... From November 15-April 15, the Action Mitigation in this area is designed
Proponents must not use MF1 surface to minimize exposure of humpback
ship hull-mounted mid-frequency whales in high-density seasonal
active sonar within the mitigation reproductive habitats (e.g., north
area. of Maui and Moloka[revaps]i) and
Main Hawaiian Islands insular false
killer whales in high seasonal
occurrence areas to levels of sound
that have the potential to cause
injurious or behavioral impacts.
Explosives......................... The Action Proponents must not Mitigation in this area is designed
detonate in-water explosives to prevent exposure of humpback
(including underwater explosives and whales in high-density seasonal
explosives deployed against surface reproductive habitats (e.g., north
targets) within the mitigation area of Maui and Moloka[revaps]i), Main
(year-round). Hawaiian Islands insular false
killer whales in high seasonal
occurrence areas, and numerous
small and resident marine mammal
populations that occur year-round
(including bottlenose dolphins,
pantropical spotted dolphins, and
spinner dolphins, and Hawaiian monk
seals) to explosives that have the
potential to cause injury,
mortality, or behavioral
disturbance.
----------------------------------------------------------------------------------------------------------------

Table 79 details special reporting requirements related to the use
of active sonar off O[revaps]ahu, Moloka[revaps]i, and Hawaii Island.
The mitigation is a continuation from Phase III with a modified
geographic extent based on based available science.

Table 79--Hawaii Humpback Whale Special Reporting Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic........................... The Action Proponents must report the Special reporting requirements are
total hours of MF1 surface ship hull- designed to aid NMFS' and the
mounted mid-frequency active sonar Action Proponents' analysis of
used from November through May in potential impacts in the mitigation
the mitigation area in their area, which contains the Hawaiian
training and testing activity Islands Humpback Whale National
reports submitted to NMFS. Marine Sanctuary plus a 5-km (2.7
nmi) sanctuary buffer (excluding
the PMRF).
----------------------------------------------------------------------------------------------------------------

Table 80 details awareness notification message requirements for
the Hawaii Range Complex. The mitigation is a continuation from Phase
III.

[[Page 32270]]

Table 80--Hawaii Humpback Whale Awareness Messages
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic, Explosives, Physical The Action Proponents must broadcast Mitigation in this area is designed
disturbance and strike. awareness messages to alert to minimize potential humpback
applicable assets (and their whale vessel interactions and
Lookouts) transiting and training or exposure to acoustic, explosive,
testing in the Hawaii Range Complex and physical disturbance and strike
to the possible presence of stressors that have the potential
concentrations of humpback whales to cause mortality, injury, or
from November through May. behavioral disturbance during the
reproductive season.
Lookouts must use that knowledge to The Hawaii Humpback Whale Awareness
help inform their visual Messages apply to the entire Hawaii
observations during military Range Complex; therefore, the
readiness activities that involve mitigation described in table 77,
vessel movements, active sonar, in- table 78, and table 79 is in
water explosives (including addition to the requirements
underwater explosives and explosives described for this overlapping
deployed against surface targets), area.
or the deployment of non-explosive
ordnance against surface targets in
the mitigation area.
----------------------------------------------------------------------------------------------------------------

Geographic Mitigation Areas in California
Table 81 details geographic mitigation related to the use of active
sonar off the coast of northern California. The mitigation is new for
this phase.

Table 81--Northern California Large Whale Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic........................... From June 1-October 31, the Action Mitigation in this area is designed
Proponents must not use more than to reduce exposure of blue whales,
300 hours of MF1 surface ship hull- fin whales, gray whales, and
mounted mid-frequency active sonar humpback whales in important
(excluding normal maintenance and seasonal foraging, migratory, and
systems checks) total during calving habitats to levels of sound
training and testing within the that have the potential to cause
combination of this mitigation area, injurious or behavioral impacts.
the Central California Large Whale
Mitigation Area, and the Southern
California Blue Whale Mitigation
Area.
----------------------------------------------------------------------------------------------------------------

Table 82 details geographic mitigation related to the use of active
sonar off the coast of Central California. The mitigation is a
continuation from Phase III with a modified geographic extent based on
best available science.

Table 82--Central California Large Whale Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic........................... From June 1-October 31, the Action Mitigation in this area is designed
Proponents must not use more than to reduce exposure of blue whales,
300 hours of MF1 surface ship hull- fin whales, gray whales, and
mounted mid-frequency active sonar humpback whales in important
(excluding normal maintenance and seasonal foraging, migratory, and
systems checks) total during calving habitats to levels of sound
training and testing within the that have the potential to cause
combination of this mitigation area, injurious or behavioral impacts.
the Northern California Large Whale
Mitigation Area, and the Southern
California Blue Whale Mitigation
Area.
----------------------------------------------------------------------------------------------------------------

Table 83 details geographic mitigation related to the use of active
sonar and explosives off the coast of Southern California. The
mitigation is a continuation from Phase III.

Table 83--Southern California Blue Whale Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic........................... From June 1-October 31, the Action Mitigation in this area is designed
Proponents must not use more than to reduce exposure of blue whales
300 hours of MF1 surface ship hull- within important seasonal foraging
mounted mid-frequency active sonar habitats to levels of sound that
(excluding normal maintenance and have the potential to cause
systems checks) total during injurious or behavioral impacts.
training and testing within the
combination of this mitigation area,
the Northern California Large Whale
Mitigation Area, and the Central
California Large Whale Mitigation
Area.

[[Page 32271]]

Explosives......................... From June 1-October 31, the Action Mitigation in this area is designed
Proponents must not detonate in- to reduce exposure of blue whales
water explosives (including within important seasonal foraging
underwater explosives and explosives habitats to explosives that have
deployed against surface targets) the potential to cause injury,
during large-caliber gunnery, mortality, or behavioral
torpedo, bombing, and missile disturbance.
(including 2.75-inch rockets)
training and testing.
----------------------------------------------------------------------------------------------------------------

Table 84 details awareness notification message requirements for
the SOCAL Range Complex. The mitigation is a continuation from Phase
III.

Table 84--California Large Whale Awareness Messages
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Acoustic, Explosives, Physical The Action Proponents must broadcast Mitigation in this area is designed
disturbance and strike. awareness messages to alert to minimize potential blue whale,
applicable assets (and their gray whale, and fin whale vessel
Lookouts) transiting and training or interactions and exposure to
testing off the U.S. West Coast to acoustic stressors, explosives, and
the possible presence of physical disturbance and strike
concentrations of large whales, stressors that have the potential
including gray whales (November- to cause mortality, injury, or
March), fin whales (November-May), behavioral disturbance during the
and mixed concentrations of blue, foraging and migration seasons, and
humpback, and fin whales that may to resident whales.
occur based on predicted
oceanographic conditions for a given
year (e.g., May-November, April-
November). Awareness messages may
provide the following types of
information which could vary
annually:
While blue whales tend to
be more transitory, some fin
whales are year-round residents
that can be expected in nearshore
waters within 10 nmi (18.5 km) of
the California mainland and
offshore operating areas at any
time.
Fin whales occur in
groups of one to three
individuals, 90 percent of the
time, and in groups of four or
more individuals, 10 percent of
the time.
Unique to fin whales
offshore southern California
(including the Santa Barbara
Channel and PMSR area), there
could be multiple individuals and/
or separate groups scattered
within a relatively small area (1-
2 nmi; 1.9-2.7 km) due to
foraging or social interactions.
When a large whale is
observed, this may be an
indicator that additional marine
mammals are present and nearby,
and the vessel should take this
into consideration when
transiting.
Lookouts must use that
knowledge to help inform their
visual observations during
military readiness activities
that involve vessel movements,
active sonar, in-water explosives
(including underwater explosives
and explosives deployed against
surface targets), or the
deployment of non-explosive
ordnance against surface targets
in the mitigation area.
----------------------------------------------------------------------------------------------------------------

Table 85 details real-time notification requirements for a
designated area within the SOCAL Range Complex. The mitigation is a
continuation from the 2025 HSTT Final Rule (90 FR 4944, January 16,
2025).

Table 85--California Large Whale Real-Time Notification Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
Physical disturbance and strike.... The Action Proponents must issue real- The real-time notification area
time notifications to alert Action encompasses the locations of recent
Proponent vessels operating in the (2009, 2021, 2023) vessel strikes,
vicinity of large whale aggregations and historic strikes where precise
(four or more whales) sighted within latitude and longitude were known.
1 nmi (1.9 km) of an Action
Proponent vessel within an area of
the Southern California Range
Complex (between 32-33 degrees North
and 117.2-119.5 degrees West).

[[Page 32272]]

The four whales that make up a
defined ``aggregation'' would not
all need to be from the same
species, and the aggregation could
consist either of a single group of
four (or more) whales, or any
combination of smaller groups
totaling four (e.g., two groups of
two whales each or a group of three
whales and a solitary whale) within
the 1 nmi (1.9 km) zone.
Lookouts must use the information
from the real-time notifications to
inform their visual observations of
applicable mitigation zones. If
Lookouts observe a large whale
aggregation within 1 nmi (1.9 km) of
the event vicinity within the area
between 32-33 degrees North and
117.2-119.5 degrees West, the watch
station must initiate communication
with the designated point of contact
to contribute to the Navy's real-
time sighting notification system.
----------------------------------------------------------------------------------------------------------------

Table 86 details geographic mitigation related to in-air vehicle
launch noise and associated monitoring for pinniped haulout locations
on San Nicolas Island, California. The mitigation is an adaptation of
procedural mitigation for the same activities in the 2022 PMSR final
rule (87 FR 40888, July 8, 2022).

Table 86--San Nicolas Island Pinniped Haulout Mitigation Area
----------------------------------------------------------------------------------------------------------------
Category Mitigation requirements Mitigation benefits
----------------------------------------------------------------------------------------------------------------
In-air vehicle launch noise........ Navy personnel must not enter Mitigation is designed to minimize
pinniped haulout or rookery areas. in-air launch noise and physical
Personnel may be adjacent to disturbance to pinnipeds hauled out
pinniped haulouts and rookery prior on beaches, as well as to continue
to and following a launch for assessing baseline pinniped
monitoring purposes. distribution/abundance and
Missiles and targets must not cross potential changes in pinniped use
over pinniped haulout areas at of these beaches after launch
altitudes less than 305 m (1,000 events.
ft), except in emergencies or for
real-time security incidents.
For unmanned aircraft systems (UAS),
the following minimum altitudes will
be maintained over pinniped haulout
areas and rookeries: Class 0-2 UAS
will maintain a minimum altitude of
92 m (300 ft); Class 3 UAS will
maintain a minimum altitude of 153 m
(500 ft); Class 4 or 5 UAS will not
be flown below 305 m (1,000 ft).
The Navy may not conduct more than 40
launch events annually.
The Navy may not conduct more than 10
launch events at night annually.
Launch events must be scheduled to
avoid the peak pinniped pupping
seasons (from January through July)
to the maximum extent practicable.
The Navy must implement a monitoring
plan using video and acoustic
monitoring of up to three pinniped
haulout areas and rookeries during
launch events that include missiles
or targets that have not been
previously monitored for at least
three launch events.
The Navy will review the launch
procedure and monitoring methods, in
cooperation with NMFS, if any
incidents of injury or mortality of
a pinniped are discovered during
post-launch surveys, or if surveys
indicate possible effects to the
distribution, size, or productivity
of the affected pinniped populations
as a result of the specified
activities. If necessary,
appropriate changes will be made
through modification to the
Authorization prior to conducting
the next launch of the same vehicle.
----------------------------------------------------------------------------------------------------------------

Mitigation Conclusions

NMFS has carefully evaluated the Action Proponents' proposed
mitigation measures--many of which were developed with NMFS' input
during the previous phases of HCTT (formerly HSTT) authorizations but
several of which are new since implementation of the 2018 to 2025
regulations--and considered a broad range of other measures (i.e., the
measures considered but eliminated in the 2024 HCTT Draft EIS/OEIS,
which reflect many of the comments that have arisen from public input
or through discussion with NMFS in past years) in the context of
ensuring that NMFS prescribes the means of effecting the least
practicable adverse impact on the affected marine mammal species and
their habitat. Our evaluation of potential measures included
consideration of the following factors in relation to one another: the
manner in

[[Page 32273]]

which, and the degree to which, the successful implementation of the
mitigation measures is expected to reduce the likelihood and/or
magnitude of adverse impacts to marine mammal species and their
habitat; the proven or likely efficacy of the measures; and the
practicability of the measures for applicant implementation, including
consideration of personnel safety, practicality of implementation, and
impact on the effectiveness of the military readiness activity.
Based on our evaluation of the Action Proponents' proposed
measures, as well as other measures considered by the Action Proponents
and NMFS (see section 5.9 (Measures Considered but Eliminated) of
chapter 5 (Mitigation) of the 2024 HCTT Draft EIS/OEIS), NMFS has
preliminarily determined that these proposed mitigation measures are
appropriate means of effecting the least practicable adverse impact on
marine mammal species and their habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and
considering specifically personnel safety, practicality of
implementation, and impact on the effectiveness of the military
readiness activity. Additionally, an adaptive management component
helps further ensure that mitigation is regularly assessed and provides
a mechanism to improve the mitigation, based on the factors above,
through modification as appropriate.
The proposed rule comment period provides the public an opportunity
to submit recommendations, views, and/or concerns regarding the Action
Proponents' activities and the proposed mitigation measures. While NMFS
has preliminarily determined that the Action Proponents' proposed
mitigation measures would effect the least practicable adverse impact
on the affected species and their habitat, NMFS will consider all
public comments to help inform our final determination. Consequently,
proposed mitigation measures may be refined, modified, removed, or
added prior to the issuance of the final rule based on public comments
received and, as appropriate, analysis of additional potential
mitigation measures.

Proposed Monitoring

Section 101(a)(5)(A) of the MMPA states that in order to authorize
incidental take for an activity, NMFS must set forth requirements
pertaining to the monitoring and reporting of such taking. The MMPA
implementing regulations at 50 CFR 216.104(a)(13) indicate that
requests for incidental take authorizations must include the suggested
means of accomplishing the necessary monitoring and reporting that will
result in increased knowledge of the species and of the level of taking
or impacts on populations of marine mammals that are expected to be
present.
Although the Navy has been conducting research and monitoring for
over 20 years in areas where it has been training, it developed a
formal marine species monitoring program in support of the HCTT Study
Area MMPA and ESA processes in 2009. Across all Navy training and
testing study areas, the robust marine species monitoring program has
resulted in hundreds of technical reports and publications on marine
mammals that have informed Navy and NMFS analyses in environmental
planning documents, rules, and Biological Opinions. The reports are
made available to the public on the Navy's marine species monitoring
website (https://www.navymarinespeciesmonitoring.us) and the data on
the Ocean Biogeographic Information System Spatial Ecological Analysis
of Megavertebrate Populations (OBIS-SEAMAP) (https://seamap.env.duke.edu/).
The Navy would continue collecting monitoring data to inform our
understanding of the occurrence of marine mammals in the HCTT Study
Area, the likely exposure of marine mammals to stressors of concern in
the HCTT Study Area, the response of marine mammals to exposures to
stressors, the consequences of a particular marine mammal response to
their individual fitness and, ultimately, populations, and the
effectiveness of implemented mitigation measures. Taken together,
mitigation and monitoring comprise the Navy's integrated approach for
reducing environmental impacts from the specified activities. The
Navy's overall monitoring approach seeks to leverage and build on
existing research efforts whenever possible.
As agreed upon between the Action Proponents and NMFS, the
monitoring measures presented here, as well as the mitigation measures
described above, focus on the protection and management of potentially
affected marine mammals. A well-designed monitoring program can provide
important feedback for validating assumptions made in analyses and
allow for adaptive management of marine mammals and their habitat, and
other marine resources. Monitoring is required under the MMPA, and
details of the monitoring program for the specified activities have
been developed through coordination between NMFS and the Action
Proponents through the regulatory process for previous Navy at-sea
training and testing activities.

Navy Marine Species Research and Monitoring Strategic Framework

The initial structure for the U.S. Navy's marine species monitoring
efforts was developed in 2009 with the Integrated Comprehensive
Monitoring Program (ICMP). The intent of the ICMP was to provide an
overarching framework for coordination of the Navy's monitoring efforts
during the early years of the program's establishment. A Strategic
Planning Process (U.S. Department of the Navy, 2013) was subsequently
developed and together with the ICMP framework serves as a planning
tool to focus marine species monitoring priorities defined by ESA and
MMPA requirements, and to coordinate monitoring efforts across regions
based on a set of common objectives. Using an underlying conceptual
framework incorporating a progression of knowledge from occurrence to
exposure/response, and ultimately consequences, the Strategic Planning
Process was developed as a tool to help guide the investment of
resources to address top level objectives and goals of the monitoring
program most efficiently. The Strategic Planning Process identifies
Intermediate Scientific Objectives (see https://www.navymarinespeciesmonitoring.us/about/strategic-planning-process/),
which form the basis of evaluating, prioritizing, and selecting new
monitoring projects or investment topics and serve as the basis for
developing and executing new monitoring projects across the Navy's
training and testing ranges (both Atlantic and Pacific).
Monitoring activities relating to the effects of military readiness
activities on marine species are generally designed to address one or
more of the following top-level goals:
An increase in the understanding of the likely occurrence
of marine mammals and ESA-listed marine species in the vicinity of the
action (i.e., presence, abundance, distribution, and density);
An increase in the understanding of the nature, scope, or
context of the likely exposure of marine mammals and ESA-listed species
to any of the potential stressors associated with the action (e.g.,
sound, explosive detonation, or military expended materials), through
better understanding of one or more of the following:
[cir] the nature of the action and its surrounding environment
(e.g., sound-source characterization, propagation, and ambient noise
levels),

[[Page 32274]]

[cir] the affected species (e.g., life history or dive patterns),
[cir] the likely co-occurrence of marine mammals and ESA-listed
marine species with the action (in whole or part), or
[cir] the likely biological or behavioral context of exposure to
the stressor for the marine mammal and ESA-listed marine species (e.g.,
age class of exposed animals or known pupping, calving, or feeding
areas).
An increase in the understanding of how individual marine
mammals or ESA-listed marine species respond (behaviorally or
physiologically) to the specific stressors associated with the action
(in specific contexts, where possible (e.g., at what distance or
received level)).
An increase in the understanding of how anticipated
individual responses, to individual stressors or anticipated
combinations of stressors, may impact either:
[cir] the long-term fitness and survival of an individual; or
[cir] the population, species, or stock (e.g., through impacts on
annual rates of recruitment or survival).
An increase in the understanding of the effectiveness of
mitigation and monitoring measures.
A better understanding and record of the manner in which
the authorized entity complies with the Incidental Take Authorization
and Incidental Take Statement.
An increase in the probability of detecting marine mammals
(through improved technology or methods), both specifically within the
mitigation zone (thus allowing for more effective implementation of the
mitigation) and in general, to better achieve the above goals; and
Ensuring that adverse impact of activities remains at the
least practicable level.
The Navy's Marine Species Monitoring Program investments are
evaluated through the Adaptive Management Review process to: (1) assess
overall progress; (2) review goals and objectives; and (3) make
recommendations for refinement and evolution of the monitoring
program's focus and direction. The Marine Species Monitoring Program
has developed and matured significantly since its inception and now
supports a portfolio of several dozen active projects across a range of
geographic areas and protected species taxa addressing both regional
priorities (i.e., particular species of concern), and Navy-wide needs
such as the behavioral response of beaked whales to training and
testing activities.
A Research and Monitoring Summit was held in early 2023 to evaluate
the current state of the Marine Species Monitoring Program in terms of
progress, objectives, priorities, and needs, and to solicit valuable
input from meeting participants including NMFS, Marine Mammal
Commission, Navy, and scientific experts. The overarching goal of the
summit was to facilitate updating the ICMP framework for guiding marine
species research and monitoring investments, and to identify data gaps
and priorities to be addressed over the next 5-10 years across a range
of basic research through applied monitoring. One of the outcomes of
this summit meeting is a refreshed strategic framework effectively
replacing the ICMP which will provide increased coordination and
synergy across the Navy's protected marine species investment programs
(see section 13.1 of the application). This will contribute to the
collective goal of supporting improved assessment of effects from
training and testing activities through development of first in class
science and data.
For over a decade, the Navy has implemented the PMAP software tool,
which provides operators with notification of the required mitigation
and a visual display of the planned training or testing activity
location overlaid with relevant environmental data. This module was
developed by civilian marine biologists employed by the Navy and was
reviewed and approved by NMFS. It provides information on marine
species sighting cues, visual observation tools and techniques, and
sighting notification procedures. It is a video-based complement to the
U.S. Navy Lookout Training Handbook or equivalent. Since 2007, this
module has been required for commanding officers, executive officers,
equivalent civilian personnel, and personnel who will stand watch as a
Lookout.
Additionally, the U.S. Navy Lookout Training Handbook was updated
in 2022 to include a more robust chapter on environmental compliance,
mitigation, and marine species observation tools and techniques.
Environmental awareness and education training is also provided to Navy
personnel through the Afloat Environmental Compliance Training program
or equivalent. Training is designed to help personnel gain an
understanding of their personal environmental compliance roles and
responsibilities (including mitigation implementation). Finally, the
Navy's current generation of land-based ship bridge simulators now
incorporate marine mammal response in team training scenarios for
bridge watch standers and Lookouts.

Past and Current Action Proponent Monitoring in the HCTT Study Area

The Navy's monitoring program has undergone significant changes
since the first rules were issued for the HRC and SOCAL Study Areas in
2009 through the process of adaptive management. The monitoring program
developed for the first cycle of environmental compliance documents
(e.g., U.S. Department of the Navy, 2008a, 2008b) utilized effort-based
compliance metrics that were somewhat limiting. Through adaptive
management discussions, the Navy designed and conducted monitoring
studies according to scientific objectives and eliminated specific
effort requirements.
Progress has also been made on the conceptual framework categories
from the Scientific Advisory Group for Navy Marine Species Monitoring
(U.S. Department of the Navy, 2011), ranging from occurrence of
animals, to their exposure, response, and population consequences. The
Navy continues to manage the Atlantic and Pacific program as a whole,
with monitoring in each range complex taking a slightly different but
complementary approach. The Navy has continued to use the approach of
layering multiple simultaneous components in many of the range
complexes to leverage an increase in return of the progress toward
answering scientific monitoring questions. For example, in later Phase
I HRC monitoring through Phase III HSTT monitoring, several monitoring
efforts coincided on the instrumented Navy training range off PMRF
during an actual anti-submarine warfare training exercise. This
included: (1) deploying civilian marine mammal observers aboard a Navy
destroyer employing mid-frequency active sonar; (2) a civilian marine
mammal aerial survey aircraft orbiting the destroyer during the course
of the exercise; (3) Navy acousticians monitoring the exercise
participants and animals via the hydrophones of the instrumented range
during the exercise; and (4) having satellite tagging of animals
performed on the training range just prior to the exercise.
Numerous publications, dissertations, and conference presentations
have resulted from research conducted under the marine species
monitoring program (https://www.navymarinespeciesmonitoring.us/reading-room/), leading to a significant contribution to the body of marine
mammal science. Publications on occurrence, distribution, and density

[[Page 32275]]

have fed the modeling input, and publications on exposure and response
have informed Navy and NMFS analysis of behavioral response and
consideration of mitigation measures.
Furthermore, collaboration between the monitoring program and the
Navy's research and development (e.g., the ONR) and demonstration-
validation (e.g., Living Marine Resources (LMR)) programs has been
strengthened, leading to research tools and products that have already
transitioned to the monitoring program. These include Marine Mammal
Monitoring on Ranges, controlled exposure experiment behavioral
response studies, acoustic sea glider surveys, and global positioning
system-enabled satellite tags. Recent progress has been made with
better integration with monitoring across all Navy at-sea study areas,
including the HCTT Study Area and various other ranges. Publications
from the LMR and ONR programs have also resulted in significant
contributions to hearing, acoustic criteria used in effects modeling,
exposure, and response, as well as in developing tools to assess
biological significance (e.g., consequences).
NMFS and the Navy also consider data collected during mitigations
as monitoring. Data are collected by shipboard personnel on hours spent
training and hours of sonar use. Additionally, during MTEs, data are
collected when marine mammals are observed within the mitigation zones
when mitigations are implemented. These data are provided to NMFS in
both classified and unclassified annual exercise reports, which would
continue under this proposed rule.
NMFS has received multiple years' worth of annual exercise and
monitoring reports addressing active sonar use and explosive
detonations within the HCTT Study Area and other Navy range complexes.
The data and information contained in these reports have been
considered in developing mitigation and monitoring measures for the
proposed military readiness activities within the HCTT Study Area. The
Navy's annual exercise and monitoring reports may be viewed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities and https://www.navymarinespeciesmonitoring.us/reporting/.
The Navy's marine species monitoring program supports several
monitoring projects in the HCTT Study Area at any given time.
Additional details on the scientific objectives for each project can be
found at: https://www.navymarinespeciesmonitoring.us/regions/pacific/current-projects/. Some projects may only require one or two years of
field effort. Other projects could entail multi-year field efforts (2-5
years). Most current HCTT projects are multi-year ongoing studies such
as odontocete tagging and behavioral response to sonar in Hawaii, and
beaked whale distribution and response to sonar in California.
Specific monitoring under the 2018-2025 regulations included the
following projects:
Pacific Marine Assessment Program for Protected Species
(PACMAPPS) survey;
Effectiveness of Navy Lookout Teams in Detecting
Cetaceans;
Long Term Acoustic Monitoring of Marine Mammals Utilizing
the Instrumented Range at Pacific Missile Range Facility (PMRF)
(ongoing);
Pacific Islands comprehensive stranding investigations
(ongoing);
North Pacific Humpback Whale Tagging;
Estimation of Received Levels of MFAS and Behavioral
Response of Marine Mammals at PMRF (ongoing);
Marine Mammal Monitoring on Navy Ranges (ongoing);
Marine Mammal Sightings During CalCOFI Cruises (ongoing);
Blue and Fin Whale Satellite Tagging;
Guadalupe Fur Seal Satellite Tracking;
Passive Acoustic Monitoring of Marine Mammals in SOCAL
Range Complex (ongoing); and
Cuvier's Beaked Whale and Fin Whale Population Dynamics
and Impact Assessment at the Southern California Offshore Antisubmarine
Warfare Range (SOAR) (ongoing).
Future monitoring efforts by the Action Proponents in the HCTT
Study Area are anticipated to continue along the same objectives:
establish the baseline habitat uses and movement patterns; establish
the baseline behavior (e.g., foraging, dive patterns, etc.); and
evaluate potential exposure and behavioral responses of marine mammals
exposed to training and testing activities.
Currently planned monitoring projects and their Intermediate
Scientific Objective for the 2025-2032 rule are listed below, many of
which are continuations of projects currently underway. Other than
those ongoing projects, monitoring projects are typically planned one
year in advance; therefore, this list does not include all projects
that will occur over the entire period of the rule.
Long Term Acoustic Monitoring of Marine Mammals Utilizing
the Instrumented Range at Pacific Missile Range Facility (PMRF)
(ongoing)--The objectives are: (1) determine what species and
populations of marine mammals and ESA-listed species are present in
Navy range complexes, testing ranges, and in specific training and
testing areas; (2) establish the baseline habitat uses, seasonality,
and movement patterns of marine mammals and ESA-listed species where
Navy training and testing activities occur; (3) evaluate potential
exposure of marine mammals and ESA-listed species to Navy training and
testing activities; (4) establish the regional baseline vocalization
behavior, including seasonality and acoustic characteristics, of marine
mammals where Navy training and testing activities occur; (5) apply
passive acoustic tools and techniques for detecting, classifying,
locating, and tracking marine mammals; (6) apply analytic methods to
evaluate exposure and/or behavioral response of marine mammals to Navy
training and testing activities; (7) evaluate acoustic exposure levels
associated with behavioral responses of marine mammals to support
development and refinement of acoustic risk functions; (8) evaluate
trends in distribution and abundance for populations of marine mammals
and ESA-listed species that are regularly exposed to Navy training and
testing activities; and (9) leverage existing data with newly developed
analysis tools and techniques.
Pacific Islands comprehensive stranding investigations
(ongoing)--The objectives are to: (1) determine what species and
populations of marine mammals and ESA-listed species are present in
Navy range complexes, testing ranges, and in specific training and
testing areas; and (2) establish the baseline habitat uses,
seasonality, and movement patterns of marine mammals and ESA-listed
species where Navy training and testing activities occur.
Estimation of Received Levels of MFAS and Behavioral
Response of Marine Mammals at PMRF (ongoing)--The objectives are to:
(1) determine what species and populations of marine mammals and ESA-
listed species are exposed to U.S. Navy training and testing
activities; (2) establish the baseline habitat uses, seasonality, and
movement patterns of marine mammals and ESA-listed species where Navy
training and testing activities occur; (3) establish the regional
baseline vocalization behavior, including seasonality and acoustic
characteristics, of marine mammals where Navy training and testing
activities occur; (4) determine what behaviors can most effectively be
assessed for potential

[[Page 32276]]

response to Navy training and testing activities; (5) evaluate
behavioral responses of marine mammals exposed to Navy training and
testing activities to support PCoD development and application; (6)
application of passive acoustic tools and techniques for detecting,
classifying, locating, and tracking marine mammals; (7) evaluate trends
in distribution and abundance for populations of marine mammals and
ESA-listed species that are regularly exposed to Navy training and
testing activities; and (8) leverage existing data with newly developed
analysis tools and techniques.
Marine Mammal Monitoring on Navy Ranges (ongoing)--The
objectives are to: (1) estimate the distribution, abundance, and
density of marine mammals and ESA-listed species in Navy range
complexes, testing ranges, and in specific training and testing areas;
(2) establish the regional baseline vocalization behavior, including
seasonality and acoustic characteristics, of marine mammals where Navy
training and testing activities occur; (3) application of passive
acoustic tools and techniques for detecting, classifying, locating, and
tracking marine mammals; (4) application of analytic methods to
evaluate exposure and/or behavioral response of marine mammals to Navy
training and testing activities; and (5) evaluate trends in
distribution and abundance for populations of marine mammals and ESA-
listed species that are regularly exposed to Navy training and testing
activities.
Marine Mammal Sightings During CalCOFI Cruises (ongoing)--
The objectives are to: (1) determine what species and populations of
marine mammals and ESA-listed species are present in Navy range
complexes, testing ranges, and in specific training and testing areas;
(2) estimate the distribution, abundance, and density of marine mammals
and ESA-listed species in Navy range complexes, testing ranges, and in
specific training and testing areas; and (3) establish the baseline
habitat uses, seasonality, and movement patterns of marine mammals and
ESA-listed species where Navy training and testing activities occur.
Passive Acoustic Monitoring of Marine Mammals in SOCAL
Range Complex (ongoing)--The objectives are to: (1) determine what
species and populations of marine mammals and ESA-listed species are
present in Navy range complexes, testing ranges, and in specific
training and testing areas; (2) establish the baseline habitat uses,
seasonality, and movement patterns of marine mammals and ESA-listed
species where Navy training and testing activities occur; (3) establish
the regional baseline vocalization behavior, including seasonality and
acoustic characteristics, of marine mammals where Navy training and
testing activities occur; and (4) apply passive acoustic tools and
techniques for detecting, classifying, locating, and tracking marine
mammals.
Cuvier's Beaked Whale and Fin Whale Population Dynamics
and Impact Assessment at the Southern California Offshore Antisubmarine
Warfare Range (SOAR) (ongoing)--The objectives are to: (1) determine
what species and populations of marine mammals and ESA-listed species
are present in Navy range complexes, testing ranges, and in specific
training and testing areas; (2) establish the baseline habitat uses,
seasonality, and movement patterns of marine mammals and ESA-listed
species where Navy training and testing activities occur; (3) establish
the regional baseline vocalization behavior, including seasonality and
acoustic characteristics, of marine mammals where Navy training and
testing activities occur, (4) determine what behaviors can most
effectively be assessed for potential response to Navy training and
testing activities; (5) apply passive acoustic tools and techniques for
detecting, classifying, locating, and tracking marine mammals; (6)
evaluate behavioral responses of marine mammals exposed to Navy
training and testing activities to support PCoD development and
application; (7) evaluate trends in distribution and abundance for
populations of marine mammals and ESA-listed species that are regularly
exposed to Navy training and testing activities; and (8) leverage
existing data with newly developed analysis tools and techniques.

Adaptive Management

The proposed regulations governing the take of marine mammals
incidental to military readiness activities in the HCTT Study Area
contain an adaptive management component. Our understanding of the
effects of military readiness activities (e.g., acoustic and explosive
stressors) on marine mammals continues to evolve, which makes the
inclusion of an adaptive management component both valuable and
necessary within the context of 7-year regulations.
The reporting requirements associated with this proposed rule are
designed to provide NMFS with monitoring data from the previous year to
allow NMFS to consider whether any changes to existing mitigation and
monitoring requirements are appropriate. The use of adaptive management
allows NMFS to consider new information from different sources to
determine (with input from the Action Proponents regarding
practicability) on an annual or biennial basis if mitigation or
monitoring measures should be modified (including additions or
deletions). Mitigation measures could be modified if new data suggests
that such modifications would have a reasonable likelihood of more
effectively accomplishing the goals of the mitigation and monitoring
and if the measures are practicable. If the modifications to the
mitigation, monitoring, or reporting measures are substantial, NMFS
would publish a notice of the planned LOAs in the Federal Register and
solicit public comment.
The following are some of the possible sources of applicable data
to be considered through the adaptive management process: (1) results
from monitoring and exercise reports, as required by MMPA
authorizations; (2) compiled results of Navy-funded research and
development studies; (3) results from specific stranding
investigations; (4) results from general marine mammal and sound
research; and (5) any information which reveals that marine mammals may
have been taken in a manner, extent, or number not authorized by these
regulations or subsequent LOAs. The results from monitoring reports and
other studies may be viewed at: https://www.navymarinespeciesmonitoring.us.

Proposed Reporting

In order to issue incidental take authorization for an activity,
section 101(a)(5)(A) of the MMPA states that NMFS must set forth
requirements pertaining to the monitoring and reporting of such taking.
Effective reporting is critical both to compliance as well as ensuring
that the most value is obtained from the required monitoring. Reports
from individual monitoring events, results of analyses, publications,
and periodic progress reports for specific monitoring projects will be
posted to the Navy's Marine Species Monitoring web portal at: https://www.navymarinespeciesmonitoring.us.
There are several different reporting requirements for the Navy
pursuant to the current regulations. All of these reporting
requirements would be continued for the Navy under this proposed rule
for the 7-year period.

Special Reporting for Geographic Mitigation Areas

The Action Proponents must report the total hours of MF1 surface
ship hull-mounted mid-frequency active sonar used from November through
May in

[[Page 32277]]

the Hawaii Humpback Whale Special Reporting Mitigation Area in their
annual training and testing activity reports. Special reporting for
this area is designed to aid the Action Proponents and NMFS in
continuing to analyze potential impacts of training and testing in the
mitigation areas. In addition to the mitigation area-specific
requirement, for all mitigation areas, should national security require
the Action Proponents to exceed the activity restrictions in a given
mitigation area, Action Proponent personnel must provide NMFS with
advance notification and include the information (e.g., sonar hours,
explosives usage, or restricted area use) in its annual activity
reports submitted to NMFS.

Notification of Injured, Live Stranded, or Dead Marine Mammals

The Action Proponents would consult the Notification and Reporting
Plan, which sets out notification, reporting, and other requirements
when injured, live stranded, or dead marine mammals are detected. The
Notification and Reporting Plan is available for review at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.

Annual HCTT Study Area Marine Species Monitoring Report

The Action Proponents would submit an annual report of the HCTT
Study Area marine species monitoring, which would be included in a
Pacific-wide monitoring report, describing the implementation and
results from the previous calendar year. Data collection methods will
be standardized across range complexes and the HCTT Study Area to allow
for comparison in different geographic locations. The draft report must
be submitted to the Director of the Office of Protected Resources of
NMFS annually as specified in the LOAs. NMFS will submit comments or
questions on the report, if any, within 3 months of receipt. The report
will be considered final after the Action Proponents have addressed
NMFS' comments, or 3 months after submittal of the draft if NMFS does
not provide comments on the draft report. The report would describe
progress of knowledge made with respect to intermediate scientific
objectives within the HCTT Study Area associated with the ICMP. Similar
study questions would be treated together so that progress on each
topic can be summarized across all Navy ranges. The report need not
include analyses and content that do not provide direct assessment of
cumulative progress on the monitoring plan study questions.

Annual HCTT Training and Testing Reports

In the event that the analyzed sound levels were exceeded, the
Action Proponents would submit a preliminary report(s) detailing the
exceedance within 21 days after the anniversary date of issuance of the
LOAs. Regardless of whether analyzed sound levels were exceeded, the
Navy would submit a detailed report (HCTT Annual Training Exercise
Report and Testing Activity Report) and Coast Guard and Army would each
submit a detailed report (HCTT Annual Training Exercise Report) to NMFS
annually as specified in the LOAs. NMFS will submit comments or
questions on the reports, if any, within 1 month of receipt. The
reports will be considered final after the Action Proponents have
addressed NMFS' comments, or 1 month after submittal of the drafts if
NMFS does not provide comments on the draft reports. The annual report
shall contain information on MTEs, ship shock trials, SINKEX events,
and a summary of all sound sources used (total hours or quantity (per
the LOA)) of each bin of sonar or other non-impulsive source; total
annual number of each type of explosive exercises; and total annual
expended/detonated rounds (e.g., missiles, bombs, sonobuoys, etc.) for
each explosive bin). The annual reports will also contain cumulative
sonar and explosive use quantity from previous years' reports through
the current year. Additionally, if there were any changes to the sound
source allowance in the reporting year, or cumulatively, the reports
would include a discussion of why the change was made and include
analysis to support how the change did or did not affect the analysis
in the 2024 HCTT Draft EIS/OEIS and MMPA final rule. The annual reports
would also include the details regarding specific requirements
associated with specific mitigation areas. The analysis in the detailed
report would be based on the accumulation of data from the current
year's report and data collected from previous annual reports. The
detailed reports shall also contain special reporting for the Hawaii
Humpback Whale Special Reporting Mitigation Area, as described in the
LOAs.
The final annual reports at the conclusion of the authorization
period (year 7) will also serve as the comprehensive close-out reports
and include both the final year annual use compared to annual
authorization as well as a cumulative 7-year annual use compared to 7-
year authorization. NMFS must submit comments on the draft close-out
report, if any, within 3 months of receipt. The reports will be
considered final after the Action Proponents have addressed NMFS'
comments, or 3 months after submittal of the drafts if NMFS does not
provide comments.

Other Reporting and Coordination

The Action Proponents would continue to report and coordinate with
NMFS for the following:
Annual marine species monitoring technical review meetings
that also include researchers and the Marine Mammal Commission; and
Annual Adaptive Management meetings that also include the
Marine Mammal Commission (and could occur in conjunction with the
annual marine species monitoring technical review meetings).

Preliminary Analysis and Negligible Impact Determination

General Negligible Impact Analysis

Introduction
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
taken by Level A harassment or Level B harassment (as presented in
table 37, table 38, table 39, and table 40), NMFS considers other
factors, such as the likely nature of any responses (e.g., intensity,
duration) and the context of any responses (e.g., critical reproductive
time or location, migration), as well as effects on habitat and the
likely effectiveness of the mitigation. We also assess the number,
intensity, and context of estimated takes by evaluating this
information relative to population status. Consistent with the 1989
preamble for NMFS' implementing regulations (54 FR 40338, September 29,
1989), the impacts from other past and ongoing anthropogenic activities
are incorporated into this analysis via their impacts on the
environmental baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, other ongoing

[[Page 32278]]

sources of human-caused mortality, and ambient noise levels).
In the Estimated Take of Marine Mammals section, we identified the
subset of potential effects that would be expected to qualify as take
under the MMPA both annually and over the 7-year period covered by this
proposed rule, and then identified the maximum number of takes we
believe could occur (mortality) or are reasonably expected to occur
(harassment) based on the methods described. The impact that any given
take will have is dependent on many case-specific factors that need to
be considered in the negligible impact analysis (e.g., the context of
behavioral exposures such as duration or intensity of a disturbance,
the health of impacted animals, the status of a species that incurs
fitness-level impacts on individuals, etc.). For this proposed rule we
evaluated the likely impacts of the enumerated maximum number of
harassment takes that are proposed for authorization and reasonably
expected to occur, in the context of the specific circumstances
surrounding these predicted takes. We also include a specific
assessment of M/SI takes that could occur, as well as consideration of
the traits and statuses of the affected species and stocks. Last, we
collectively evaluated this information, as well as other more taxa-
specific information and mitigation measure effectiveness, in group-
specific assessments that support our negligible impact conclusions for
each stock or species. Because all of the Action Proponents' specified
activities would occur within the ranges of the marine mammal stocks
identified in the rule, all negligible impact analyses and
determinations are at the stock level (i.e., additional species-level
determinations are not needed).
Harassment
The specified activities reflect representative levels of military
readiness activities. The Description of the Proposed Activity section
describes annual activities. There may be some flexibility in the exact
number of hours, items, or detonations that may vary from year to year,
but take totals would not exceed the maximum annual totals and 7-year
totals indicated in table 37, table 38, table 39, and table 40. We base
our analysis and negligible impact determination on the maximum number
of takes that would be reasonably expected to occur annually and are
proposed to be authorized, although, as stated before, the number of
takes are only one part of the analysis, which includes extensive
qualitative consideration of other contextual factors that influence
the degree of impact of the takes on the affected individuals. To avoid
repetition, we provide some general analysis immediately below that
applies to all the species listed in table 37, table 38, table 39, and
table 40, given that some of the anticipated effects of the Action
Proponents' military readiness activities on marine mammals are
expected to be relatively similar in nature. Below that, we provide
additional information specific to mysticetes, odontocetes, and
pinnipeds and, finally, break our analysis into species (and/or
stocks), or groups of species (and the associated stocks) where
relevant similarities exist, to provide more specific information
related to the anticipated effects on individuals of a specific stock
or where there is information about the status or structure of any
species that would lead to a differing assessment of the effects on the
species or stock. Organizing our analysis by grouping species or stocks
that share common traits or that will respond similarly to effects of
the Action Proponents' activities and then providing species- or stock-
specific information allows us to avoid duplication while assuring that
we have analyzed the effects of the specified activities on each
affected species or stock.
The Action Proponents' harassment take request is based on one
model for pile driving, a second model for land-based missile and
target launches, and a third model (NAEMO) for all other acoustic
stressors, which NMFS reviewed and concurs appropriately estimates the
maximum amount of harassment that is reasonably likely to occur. As
described in more detail above, NAEMO calculates sound energy
propagation from sonar and other transducers, air guns, and explosives
during military readiness activities; the sound or impulse received by
animat dosimeters representing marine mammals distributed in the area
around the modeled activity; and whether the sound or impulse energy
received by a marine mammal exceeds the thresholds for effects.
Assumptions in the Navy models intentionally err on the side of
overestimation when there are unknowns. The effects of the specified
activities are modeled as though they would occur regardless of
proximity to marine mammals, meaning that no activity-based mitigation
is considered (e.g., no power down or shut down). However, the modeling
does quantitatively consider the possibility that marine mammals would
avoid continued or repeated sound exposures to some degree, based on a
species' sensitivity to behavioral disturbance. NMFS provided input to,
independently reviewed, and concurred with the Action Proponents on
this process. The Action Proponents' analysis, which is described in
detail in section 6 of the application, was used to quantify harassment
takes for this proposed rule.
The Action Proponents and NMFS anticipate more severe effects from
takes resulting from exposure to higher received levels (though this is
in no way a strictly linear relationship for behavioral effects
throughout species, individuals, or circumstances) and less severe
effects from takes resulting from exposure to lower received levels.
However, there is also growing evidence of the importance of distance
in predicting marine mammal behavioral response to sound, i.e., sounds
of a similar level emanating from a more distant source have been shown
to be less likely to elicit a response of equal magnitude (DeRuiter
2012). The estimated number of takes by Level A harassment and Level B
harassment does not equate to the number of individual animals the
Action Proponents expect to harass (which is lower), but rather to the
instances of take (i.e., exposures above the Level A harassment and
Level B harassment threshold) that are anticipated to occur over the 7-
year period. These instances may represent either brief exposures
(i.e., seconds or minutes) or, in some cases, longer durations of
exposure within a day. In some cases, an animal that incurs a single
take by AUD INJ or TTS may also experience a direct behavioral
harassment from the same exposure. Some individuals may experience
multiple instances of take (meaning over multiple days) over the course
of the year, which means that the number of individuals taken is
smaller than the total estimated takes. Generally speaking, the higher
the number of takes as compared to the population abundance, the more
repeated takes of individuals are likely, and the higher the actual
percentage of individuals in the population that are likely taken at
least once in a year. We look at this comparative metric (number of
takes to population abundance) to give us a relative sense of where a
larger portion of a species is being taken by the specified activities,
where there is a likelihood that the same individuals are being taken
across multiple days, and whether the number of days might be higher or
more likely sequential. Where the number of instances of take is less
than 100 percent of the abundance, and there is no information to
specifically suggest that some subset of animals is known to congregate
in an area in which

[[Page 32279]]

activities are regularly occurring (e.g., a small resident population,
takes occurring in a known important area such as a BIA, or a large
portion of the takes occurring in a certain region and season), the
overall likelihood and number of repeated takes is generally considered
low, as it could, on one extreme, mean that every take represents a
separate individual in the population being taken on one day (a minimal
impact to an individual) or, more likely, that some smaller number of
individuals are taken on one day annually and some are taken on a few,
not likely sequential, days annually, and of course some are not taken
at all.
In the ocean, the use of sonar and other active acoustic sources is
often transient and is unlikely to repeatedly expose the same
individual animals within a short period, for example within one
specific exercise. However, for some individuals of some species,
repeated exposures across different activities could occur over the
year, especially where events occur in generally the same area with
more resident species. In short, for some species, we expect that the
total anticipated takes represent exposures of a smaller number of
individuals of which some would be exposed multiple times, but based on
the nature of the specified activities and the movement patterns of
marine mammals, it is unlikely that individuals from most stocks would
be taken over more than a few days within a given year. This means that
even where repeated takes of individuals are likely to occur, they are
more likely to result from non-sequential exposures from different
activities, and, even if sequential, individual animals are not
predicted to be taken for more than several days in a row, at most. As
described elsewhere, the nature of the majority of the exposures would
be expected to be of a less severe nature, and based on the numbers, it
is likely that any individual exposed multiple times is still only
taken on a small percentage of the days of the year. The greater
likelihood is that not every individual is taken, or perhaps a smaller
subset is taken with a slightly higher average and larger variability
of highs and lows, but still with no reason to think that, for most
species or stocks, any individuals would be taken a significant portion
of the days of the year.
Behavioral Response
The estimates calculated using the BRF do not differentiate between
the different types of behavioral responses that qualify as Level B
harassment. As described in the application, the Action Proponents
identified, with NMFS' input, that moderate behavioral responses, as
characterized in Southall et al. (2021), would be considered a take.
The behavioral responses predicted by the BRFs are assumed to be
moderate severity exposures (e.g., altered migration paths or dive
profiles, interrupted nursing, breeding or feeding, or avoidance) that
may last for the duration of an exposure. The Action Proponents then
compiled the available data indicating at what received levels and
distances those responses have occurred, and used the indicated
literature to build biphasic behavioral response curves and cut-off
conditions that are used to predict how many instances of Level B
behavioral harassment occur in a day (see the Criteria and Thresholds
Technical Report). Take estimates alone do not provide information
regarding the potential fitness or other biological consequences of the
responses on the affected individuals. We therefore consider the
available activity-specific, environmental, and species-specific
information to determine the likely nature of the modeled behavioral
responses and the potential fitness consequences for affected
individuals.
Use of sonar and other transducers would typically be transient and
temporary. The majority of acoustic effects to individual animals from
sonar and other active sound sources during military readiness
activities would be primarily from anti-submarine warfare events. It is
important to note although anti-submarine warfare is one of the warfare
areas of focus during MTEs, there are significant periods when active
anti-submarine warfare sonars are not in use. Nevertheless, behavioral
responses are assumed more likely to be significant during MTEs than
during other anti-submarine warfare activities due to the duration
(i.e., multiple days), scale (i.e., multiple sonar platforms), and use
of high-power hull-mounted sonar in the MTEs. In other words, in the
range of potential behavioral effects that might be expected as part of
a response that qualifies as an instance of Level B behavioral
harassment (which by nature of the way it is modeled/counted, occurs
within 1 day), the less severe end might include exposure to
comparatively lower levels of a sound, at a detectably greater distance
from the animal, for a few or several minutes, and that could result in
a behavioral response such as avoiding an area that an animal would
otherwise have chosen to move through or feed in for some amount of
time or breaking off one or a few feeding bouts. More severe effects
could occur when the animal gets close enough to the source to receive
a comparatively higher level, is exposed continuously to one source for
a longer time, or is exposed intermittently to different sources
throughout a day. Such effects might result in an animal having a more
severe flight response and leaving a larger area for a day or more or
potentially losing feeding opportunities for a day. However, such
severe behavioral effects are expected to occur infrequently.
To help assess this, for sonar (LFAS/MFAS/HFAS) used in the HCTT
Study Area, the Action Proponents provided information estimating the
instances of take by Level B harassment by behavioral disturbance under
each BRF that would occur within 6-dB increments (discussed below in
the Group and Species-Specific Analyses section), and by distance in 5-
km bins in section 2.3.3 of appendix A of the application. As mentioned
above, all else being equal, an animal's exposure to a higher received
level is more likely to result in a behavioral response that is more
likely to lead to adverse effects, which could more likely accumulate
to impacts on reproductive success or survivorship of the animal, but
other contextual factors (e.g., distance, duration of exposure, and
behavioral state of the animals) are also important (Di Clemente et
al., 2018; Ellison et al., 2012; Moore and Barlow, 2013; Southall et
al., 2019; Wensveen et al., 2017, etc.). The majority of takes by Level
B harassment are expected to be in the form of comparatively milder
responses (i.e., lower-level exposures that still qualify as take under
the MMPA, but would likely be less severe along the continuum of
responses that qualify as take) of a generally shorter duration. We
anticipate more severe effects from takes when animals are exposed to
higher received levels of sound or at closer proximity to the source.
Because species belonging to taxa that share common characteristics are
likely to respond and be affected in similar ways, these discussions
are presented within each species group below in the Group and Species-
Specific Analyses section. As noted previously in this proposed rule,
behavioral response is likely highly variable between species,
individuals within a species, and context of the exposure.
Specifically, given a range of behavioral responses that may be
classified as Level B harassment, to the degree that higher received
levels of sound are expected to result in more severe behavioral
responses, only a smaller percentage of the anticipated Level B
harassment from the specified

[[Page 32280]]

activities might result in more severe responses (see the Group and
Species-Specific Analyses section below for more detailed information).
Physiological Stress Response
Some of the lower level physiological stress responses (e.g.,
orientation or startle response, change in respiration, change in heart
rate) discussed earlier would likely co-occur with the predicted
harassments, although these responses are more difficult to detect and
fewer data exist relating these responses to specific received levels
of sound. Level B harassment takes, then, may have a stress-related
physiological component as well; however, we would not expect the
Action Proponents' generally short-term, intermittent, and (typically
in the case of sonar) transitory activities to create conditions of
long-term continuous noise leading to long-term physiological stress
responses in marine mammals that could affect reproduction or survival.
Diel Cycle
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing on a diel cycle (24-hour cycle). Behavioral
responses to noise exposure, when taking place in a biologically
important context, such as disruption of critical life functions,
displacement, or avoidance of important habitat, are more likely to be
significant if they last more than one diel cycle or recur on
subsequent days (Southall et al., 2007). Henderson et al. (2016) found
that ongoing smaller scale events had little to no impact on foraging
dives for Blainville's beaked whale, while multi-day training events
may decrease foraging behavior for Blainville's beaked whale (Manzano-
Roth et al., 2016). Consequently, a behavioral response lasting less
than one day and not recurring on subsequent days is not considered
severe unless it could directly affect reproduction or survival
(Southall et al., 2007). Note that there is a difference between
multiple-day substantive behavioral responses and multiple-day
anthropogenic activities. For example, just because an at-sea exercise
lasts for multiple days does not necessarily mean that individual
animals are either exposed to those exercises for multiple days or,
further, exposed in a manner resulting in a sustained multiple day
substantive behavioral response. Large multi-day Navy exercises, such
as anti-submarine warfare activities, typically include vessels moving
faster than while in transit (typically 10-15 kn (18.5-27.8 km/hr) or
higher) and generally cover large areas that are relatively far from
shore (typically more than 3 nmi (5.6 km) from shore) and in waters
greater than 600 ft (182.9 m) deep. Marine mammals are moving as well,
which would make it unlikely that the same animal could remain in the
immediate vicinity of the ship for the entire duration of the exercise.
Further, the Action Proponents do not necessarily operate active sonar
the entire time during an exercise. While it is certainly possible that
these sorts of exercises could overlap with individual marine mammals
multiple days in a row at levels above those anticipated to result in a
take, because of the factors mentioned above, it is considered unlikely
for the majority of takes. However, it is also worth noting that the
Action Proponents conduct many different types of noise-producing
activities over the course of the year and it is likely that some
marine mammals will be exposed to more than one activity and taken on
multiple days, even if they are not sequential.
Durations of Navy activities utilizing tactical sonar sources and
explosives vary and are fully described in chapter 2 of the 2024 HCTT
Draft EIS/OEIS. Sonar used during anti-submarine warfare would impart
the greatest amount of acoustic energy of any category of sonar and
other transducers analyzed in the application and include hull-mounted,
towed, line array, sonobuoy, helicopter dipping, and torpedo sonars.
Most anti-submarine warfare sonars are MFAS (1-10 kHz); however, some
sources may use higher or lower frequencies. Anti-submarine warfare
training and testing activities using hull-mounted sonar proposed for
the HCTT Study Area generally last for only a few hours. However, anti-
submarine warfare testing activities range from several hours, to days,
to more than 10 days for large integrated anti-submarine warfare MTEs
(see table 2, table 3, and table 7). For these multi-day exercises
there will typically be extended intervals of non-activity in between
active sonar periods. Because of the need to train in a large variety
of situations, the Navy conducts anti-submarine warfare activities in
varying locations. Given the average length and dynamic nature of anti-
submarine warfare activities (times of sonar use) and typical vessel
speed, combined with the fact that the majority of the cetaceans would
not likely remain in proximity to the sound source, it is unlikely that
an animal would be exposed to LFAS/MFAS/HFAS at levels or durations
likely to result in a substantive response that would then be carried
on for more than one day or on successive days.
Most planned explosive events are instantaneous or scheduled to
occur over a short duration (less than 2 hours) and the explosive
component of these activities only lasts for minutes. Although
explosive activities may sometimes be conducted in the same general
areas repeatedly, because of their short duration and the fact that
they are in the open ocean and animals can easily move away, it is
similarly unlikely that animals would be exposed for long, continuous
amounts of time, or demonstrate sustained behavioral responses.
Although SINKEXs may last for up to 48 hours (4-8 hours typically,
possibly 1-2 days), they are almost always completed in a single day
and only a maximum of one event is planned annually for SOCAL and 2-3
annually in Hawaii (see table 3). They are stationary and conducted in
deep, open water (where fewer marine mammals would typically be
expected to be randomly encountered), and they have rigorous monitoring
(see table 69) and shutdown procedures all of which make it unlikely
that individuals would be exposed to the exercise for extended periods
or on consecutive days, though some individuals may be exposed on
multiple days.
Assessing the Number of Individuals Taken and the Likelihood of
Repeated Takes
As described previously, Navy modeling uses the best available
science to predict the instances of exposure above certain acoustic
thresholds, which are equated, as appropriate, to harassment takes. As
further noted, for active acoustics it is more challenging to parse out
the number of individuals taken by Level B harassment and the number of
times those individuals are taken from this larger number of instances,
though factors such as movement ecology (e.g., is the species resident
and more likely to remain in closer proximity to ongoing activities,
versus nomadic or migratory; Keen et al. (2021)) or whether there are
known BIAs where animals are known to congregate can help inform this.
One method that NMFS uses to help better understand the overall scope
of the impacts is to compare these total instances of take against the
abundance of that species (or stock if applicable). For example, if
there are 100 harassment takes in a population of 100, one can assume
either that every individual was exposed above acoustic thresholds once
per year, or that some smaller number were exposed a few times per
year, and a few were not exposed at all. Where the

[[Page 32281]]

instances of take exceed 100 percent of the population, multiple takes
of some individuals are predicted and expected to occur within a year.
Generally speaking, the higher the number of takes as compared to the
population abundance, the more multiple takes of individuals are
likely, and the higher the actual percentage of individuals in the
population that are likely taken at least once in a year. We look at
this comparative metric to give us a relative sense of where larger
portions of the species are being taken by the Action Proponents'
activities and where there is a higher likelihood that the same
individuals are being taken across multiple days and where that number
of days might be higher. It also provides a relative picture of the
scale of impacts on each species.
In the ocean, unlike a modeling simulation with static animals, the
transient nature of sonar use makes it unlikely to repeatedly expose
the same individual animals within a short period, for example, within
one specific exercise. However, some repeated exposures across
different activities could occur over the year with more resident
species. In short, we expect the total anticipated takes represent
exposures of a smaller number of individuals of which some could be
exposed multiple times, but based on the nature of the Action
Proponents' activities and the movement patterns of marine mammals, it
is unlikely that any particular subset would be taken over more than
several sequential days (with a few possible exceptions discussed in
the species-specific conclusions). In other cases, such as activities
that overlap habitat of small and resident populations, repeated
exposures of the same individuals may be more likely given the
likelihood that a smaller number of animals would routinely use the
affected habitat.
When calculating the proportion of a population taken (e.g., the
number of takes divided by population abundance), which can also be
helpful in estimating the number of days over which some individuals
may be taken, it is important to choose an appropriate population
estimate against which to make the comparison. Herein, NMFS considers
two potential abundance estimates, the SARs and the NMSDD abundance
estimates. The SARs, where available, provide the official population
estimate for a given species or stock in U.S. waters in a given year.
These estimates are typically generated from the most recent shipboard
and/or aerial surveys conducted, and in some cases, the estimates show
substantial year-to-year variability. When the stock is known to range
well outside of U.S. Exclusive Economic Zone (EEZ) boundaries,
population estimates based on surveys conducted only within the U.S.
EEZ are known to be underestimates. The NMSDD-derived abundance
estimates are abundances for within the boundaries described for the
density database for the California and Hawaii Study Areas only and,
therefore, differ from some SAR abundance estimates. For the California
Study Area, the NMSDD abundances are based on the extent of the west
coast density models, which include areas off the Baja California
peninsula of Mexico to the south but are truncated to the north and
west of the California portion of the Study Area as shown in the
Density Technical Report. For some species, the NMSDD abundances are
based on density models that extend up to the northern extent of the
west coast U.S. EEZ, beyond the HCTT Study Area. These are noted in the
table. In some instances, even this larger extent does not cover the
full range of a species or stock. For the Hawaii Study Area, the NMSDD
abundances are based on a buffer around the Hawaiian island chain.
Thus, island-associated species are encompassed, but abundances of
wider-ranging species may be underestimated.
The SAR and NMSDD abundance estimates can differ substantially
because these estimates may be based on different methods and data
sources. For example, the SARs only consider data from the past 8 year
period, whereas the NMSDD considers a longer data history. Further, the
SARs estimate the number of animals in a population but not spatial
densities. NMSDD uses predictive density models to estimate species
presence, even where sighting data is limited or lacking altogether.
Each density model is limited to the variables and assumptions
considered by the original data source provider. NMFS considered these
factors and others described in the Density Technical Report when
comparing the estimated takes to current population abundances for each
species or stock.
In consideration of the factors described above, to estimate
repeated impacts across large areas relative to species geographic
distributions, comparing the impacts predicted in NAEMO to abundances
predicted using the NMSDD models is usually preferable. By comparing
estimated take to the NMSDD abundance estimates, impacts and abundance
estimates are based on the same underlying assumptions about a species'
presence. NMFS has compared the estimated take to the NMSDD abundance
estimates herein for all stocks, with the exception of stocks where the
abundance information fits into one of the following scenarios, in
which case NMFS concluded that comparison to the SAR abundance estimate
is more appropriate: (1) a species' or stocks' range extends beyond the
U.S. EEZ and the SAR abundance estimate is greater than the NMSDD
abundance. For highly migratory species (e.g., large whales) or those
whose geographic distribution extends beyond the boundaries of the HCTT
Study Area (e.g., Alaska stocks), comparisons to the SAR are
appropriate. Many of the stocks present in the HCTT Study Area have
ranges significantly larger than the HCTT Study Area, and that
abundance is captured by the SAR. Therefore, comparing the estimated
takes to an abundance, in this case the SAR abundance, which represents
the total population, may be more appropriate than modeled abundances
for only the HCTT Study Area; and (2) when the current minimum
population estimate in the SAR is greater than the NMSDD abundance,
regardless of whether the stock range extends beyond the EEZ. The NMSDD
and SAR abundance estimates are both included in table 89, table 91,
table 93, table 95, table 97, and table 99, and each table indicates
which stock abundance estimate was selected for comparison to the take
estimate for each species or stock.
Temporary Threshold Shift
NMFS and the Navy have estimated that all species of marine mammals
may incur some level of TTS from active sonar. As mentioned previously,
in general, TTS can last from a few minutes to days, be of varying
degree, and occur across various frequency bandwidths, all of which
determine the severity of the impacts on the affected individual, which
can range from minor to more severe. Table 41 through table 51 indicate
the number of takes by TTS that may be incurred by different species
from exposure to active sonar, air guns, pile driving, and explosives.
The TTS incurred by an animal is primarily characterized by three
characteristics:
1. Frequency--Available data suggest that most TTS occurs in the
frequency range of the source up to one octave higher than the source
(with the maximum TTS at \1/2\ octave above) (Finneran 2015; Southall
et al., 2019). The Navy's MF anti-submarine warfare sources, which are
the highest power and most numerous sources and the ones that cause the
most take by TTS, utilize the 1-10 kHz frequency band, which suggests
that if TTS were to be

[[Page 32282]]

induced by any of these MF sources it would be in a frequency band
somewhere between approximately 1 and 20 kHz, which is in the range of
communication calls for many odontocetes, but below the range of the
echolocation signals used for foraging. There are fewer hours of HF
source use and the sounds would attenuate more quickly, plus they have
lower source levels, but if an animal were to incur TTS from these
sources, it would cover a higher frequency range (sources are between
10 and 100 kHz, which means that TTS could range up to the highest
frequencies audible to VHF cetaceans, approaching 200 kHz), which could
overlap with the range in which some odontocetes communicate or
echolocate. However, HF systems are typically used less frequently and
for shorter time periods than surface ship and aircraft MF systems, so
TTS from HF sources is less likely than from MF sources. There are
fewer LF sources and the majority are used in the more readily
mitigated testing environment, and TTS from LF sources would most
likely occur below 2 kHz, which is in the range where many mysticetes
communicate and also where other auditory cues are located (waves,
snapping shrimp, fish prey). Also of note, the majority of sonar
sources from which TTS may be incurred occupy a narrow frequency band,
which means that the TTS incurred would also be across a narrower band
(i.e., not affecting the majority of an animal's hearing range).
2. Degree of the shift (i.e., by how many dB the sensitivity of the
hearing is reduced)--Generally, both the degree of TTS and the duration
of TTS will be greater if the marine mammal is exposed to a higher
level of energy (which would occur when the peak SPL is higher or the
duration is longer). The threshold for the onset of TTS was discussed
previously in this proposed rule. An animal would have to approach
closer to the source or remain in the vicinity of the sound source
appreciably longer to increase the received SEL, which would be
difficult considering the Lookouts and the nominal speed of an active
sonar vessel (10-15 kn (18.5-27.8 km/hr)) and the relative motion
between the sonar vessel and the animal. In the TTS studies discussed
in the Potential Effects of Specified Activities on Marine Mammals and
Their Habitat section, some using exposures of almost an hour in
duration or up to 217 SEL, most of the TTS induced was 15 dB or less,
though Finneran et al. (2007) induced 43 dB of TTS with a 64-second
exposure to a 20 kHz source measured via auditory steady-state response
(auditory evoked potential measurement). The SQS-53 (MFAS) hull-mounted
sonar (MF1) nominally emits a short (i.e., 1-second) ping typically
every 50 seconds, incurring those levels of TTS due to this source is
highly unlikely. Sources with higher duty cycles, such as MF1C (high
duty cycle hull-mounted sonar) produce longer ranges to effects and
contribute to auditory effects from this action. Since most hull-
mounted sonar, such as the SQS-53, engaged in anti-submarine warfare
training would be moving at between 10 and 15 kn (18.5 to 27.8 km/hr)
and nominally pinging every 50 seconds, the vessel will have traveled a
minimum distance of approximately 843.2 ft (257 m) during the time
between those pings. For a Navy vessel moving at a nominal 10 kn (18.5
km/hr), it is unlikely a marine mammal would track with the ship and
could maintain speed parallel to the ship to receive adequate energy
over successive pings to suffer TTS. In general, there is a higher
potential for TTS associated with sources with higher duty cycles, like
continuous hull-mounted sonars, compared to those sources that are
intermittent or have lower duty cycles (Kastelein et al., 2015). Though
high duty cycle or continuous hull-mounted sonars make up a small
percentage of the Navy's overall MFAS activities.
In short, given the anticipated duration and levels of sound
exposure, we would not expect marine mammals to incur more than
relatively low levels of TTS in most cases for sonar exposure. To add
context to this degree of TTS, individual marine mammals may regularly
experience variations of 6 dB differences in hearing sensitivity in
their lifetime (Finneran et al., 2000; Finneran et al., 2002; Schlundt
et al., 2000).
3. Duration of TTS (recovery time)--As discussed in the Potential
Effects of Specified Activities on Marine Mammals and Their Habitat
section, TTS laboratory studies using exposures of up to an hour in
duration or up to 217 dB SEL, most individuals recovered within 1 day
(or less, often in minutes) (Kastelein, 2020b). One study resulted in a
recovery that took 4 days (Finneran et al., 2015; Southall et al.,
2019). However, there is evidence that repeated exposures resulting in
TTS could potentially lead to residual threshold shifts that persist
for longer durations and can result in PTS (Reichmuth et al., 2019).
Compared to laboratory studies, marine mammals are likely to
experience lower SELs from sonar used in the HCTT Study Area due to
movement of the source and animals, and because of the lower duty
cycles typical of higher power sources (though some of the Navy MF1C
sources have higher duty cycles). Therefore, TTS resulting from MFAS
would likely be of lesser magnitude and duration compared to laboratory
studies. Also, for the same reasons discussed in the Preliminary
Analysis and Negligible Impact Determination--Diel Cycle section, and
because of the short distance between the source and animals needed to
reach high SELs, it is unlikely that animals would be exposed to the
levels necessary to induce TTS in subsequent time periods such that
hearing recovery is impeded. Additionally, though the frequency range
of TTS that marine mammals might incur would overlap with some of the
frequency ranges of their vocalization types, the frequency range of
TTS from MFAS would not usually span the entire frequency range of one
vocalization type, much less span all types of vocalizations or other
critical auditory cues.
As a general point, the majority of the TTS takes are the result of
exposure to hull-mounted MFAS, with fewer from explosives (broad-band
lower frequency sources), and even fewer from LFAS or HFAS sources
(narrower band). As described above, we expect the majority of these
takes to be in the form of mild, short-term (minutes to hours),
narrower band (only affecting a portion of the animal's hearing range)
TTS. This means that for one to several times per year, for several
minutes, maybe a few hours, or at most in limited circumstances a few
days, a taken individual will have diminished hearing sensitivity
(i.e., more than natural variation, but nowhere near total deafness).
More often than not, such an exposure would occur within a narrower
mid- to higher frequency band that may overlap part (but not all) of a
communication, echolocation, or predator range, but sometimes across a
lower or broader bandwidth. The significance of TTS is also related to
the auditory cues that are germane within the time period that the
animal incurs the TTS. For example, if an odontocete has TTS at
echolocation frequencies, but incurs it at night when it is resting and
not feeding, it may not be as impactful. In short, the expected results
of any one of these limited number of mild TTS occurrences could be
that: (1) it does not overlap signals that are pertinent to that animal
in the given time period; (2) it overlaps parts of signals that are
important to the animal, but not in a manner that impairs
interpretation; or (3) it reduces detectability of an important signal
to a small degree for a

[[Page 32283]]

short amount of time--in which case the animal may be aware and be able
to compensate (but there may be slight energetic cost), or the animal
may have some reduced opportunities (e.g., to detect prey) or reduced
capabilities to react with maximum effectiveness (e.g., to detect a
predator or navigate optimally). However, it is unlikely that
individuals would experience repeated or high degree TTS overlapping in
frequency and time with signals critical for behaviors that would
impact overall fitness.
Auditory Masking or Communication Impairment
The ultimate potential impacts of masking on an individual (if it
were to occur) are similar to those discussed for TTS, but an important
difference is that masking only occurs during the time of the signal,
versus TTS, which continues beyond the duration of the signal.
Fundamentally, masking is referred to as a chronic effect because one
of the key harmful components of masking is its duration--the fact that
an animal would have reduced ability to hear or interpret critical cues
becomes much more likely to cause a problem the longer it occurs. Also
inherent in the concept of masking is the fact that the potential for
the effect is only present during the times that the animal and the
source are in close enough proximity for the effect to occur (and
further, this time period would need to coincide with a time that the
animal was utilizing sounds at the masked frequency). As our analysis
has indicated, because of the relative movement of vessels and the
sound sources primarily involved in this proposed rule, we do not
expect the exposures with the potential for masking to be of a long
duration.
Masking is fundamentally more of a concern at lower frequencies,
because low frequency signals propagate significantly farther than
higher frequencies and because they are more likely to overlap both the
narrower LF calls of mysticetes, as well as many non-communication cues
such as fish and invertebrate prey, and geologic sounds that inform
navigation. Masking is also more of a concern from continuous sources
(versus intermittent sonar signals) where there is no quiet time
between pulses and detection and interpretation of auditory signals is
likely more challenging. For these reasons, dense aggregations of, and
long exposure to, continuous LF activity are much more of a concern for
masking, whereas comparatively short-term exposure to the predominantly
intermittent pulses of often narrow frequency range MFAS or HFAS, or
explosions are not expected to result in a meaningful amount of
masking. While the Action Proponents occasionally use LF and more
continuous sources, it is not in the contemporaneous aggregate amounts
that would be expected to accrue to degrees that would have the
potential to affect reproductive success or survival. Additional detail
is provided below.
Standard hull-mounted MFAS typically pings every 50 seconds. Some
hull-mounted anti-submarine sonars can also be used in an object
detection mode known as ``Kingfisher'' mode (e.g., used on vessels when
transiting to and from port) where pulse length is shorter but pings
are much closer together in both time and space since the vessel goes
slower when operating in this mode, and during which an increased
likelihood of masking in the vicinity of vessel could be expected. For
the majority of other sources, the pulse length is significantly
shorter than hull-mounted active sonar, on the order of several
microseconds to tens of milliseconds. Some of the vocalizations that
many marine mammals make are less than 1 second long, so, for example
with hull-mounted sonar, there would be a 1 in 50 chance (only if the
source was in close enough proximity for the sound to exceed the signal
that is being detected) that a single vocalization might be masked by a
ping. However, when vocalizations (or series of vocalizations) are
longer than the 1 second pulse of hull-mounted sonar, or when the
pulses are only several microseconds long, the majority of most
animals' vocalizations would not be masked.
Most anti-submarine warfare sonars and countermeasures use MF
frequencies and a few use LF and HF frequencies. Most of these sonar
signals are limited in the temporal, frequency, and spatial domains.
The duration of most individual sounds is short, lasting up to a few
seconds each. A few systems operate with higher duty cycles or nearly
continuously, but they typically use lower power, which means that an
animal would have to be closer, or in the vicinity for a longer time,
to be masked to the same degree as by a higher level source.
Nevertheless, masking could occasionally occur at closer ranges to
these high-duty cycle and continuous active sonar systems, but, as
described previously, it would be expected to be of a short duration.
While data are lacking on behavioral responses of marine mammals to
continuously active sonars, mysticete species are known to habituate to
novel and continuous sounds (Nowacek et al., 2004), suggesting that
they are likely to have similar responses to high-duty cycle sonars.
Furthermore, most of these systems are hull-mounted on surface ships
with the ships moving at least 10 kn (18.5 km/hr), and it is unlikely
that the ship and the marine mammal would continue to move in the same
direction and the marine mammal subjected to the same exposure due to
that movement. Most anti-submarine warfare activities are
geographically dispersed and last for only a few hours, often with
intermittent sonar use even within this period. Most anti-submarine
warfare sonars also have a narrow frequency band (typically less than
one-third octave). These factors reduce the likelihood of sources
causing significant masking. HF signals (above 10 kHz) attenuate more
rapidly in the water due to absorption than do lower frequency signals,
thus producing only a very small zone of potential masking. If masking
or communication impairment were to occur briefly, it would more likely
be in the frequency range of MFAS (the more powerful source), which
overlaps with some odontocete vocalizations (but few mysticete
vocalizations); however, it would likely not mask the entirety of any
particular vocalization, communication series, or other critical
auditory cue, because the signal length, frequency, and duty cycle of
the MFAS/HFAS signal does not perfectly resemble the characteristics of
any single marine mammal species' vocalizations.
Other sources used in the Action Proponents' training and testing
that are not explicitly addressed above, many of either higher
frequencies (meaning that the sounds generated attenuate even closer to
the source) or used less frequently, would be expected to contribute to
masking over far smaller areas and/or times. For the reasons described
here, any limited masking that could potentially occur would be minor
and short-term.
In conclusion, masking is more likely to occur in the presence of
broadband, relatively continuous noise sources such as from vessels;
however, the duration of temporal and spatial overlap with any
individual animal and the spatially separated sources that the Action
Proponents use would not be expected to result in more than short-term,
low impact masking that would not affect reproduction or survival.
Auditory Injury from Sonar Acoustic Sources and Explosives and Non-
Auditory Injury from Explosives
Table 41 through table 51 indicate the number of takes of each
species by Level A harassment in the form of auditory injury resulting
from exposure to active sonar and/or explosives is estimated to

[[Page 32284]]

occur, and table 54 indicates the totals across all activities. The
number of takes estimated to result from auditory injury annually from
sonar, air guns, and explosives for each species/stock from all
activities combined ranges from 0 to 1,235 (the 1,235 is for the CA/OR/
WA stock of Dall's porpoise). Thirty-two stocks have the potential to
incur non-auditory injury from explosives, and the number of
individuals from any given stock from all activities combined ranges
from 1 to 71 (the 71 is for the CA/OR/WA stock of short-beaked common
dolphin). As described previously, the Navy's model likely
overestimates the number of injurious takes to some degree.
Nonetheless, these Level A harassment take numbers represent the
maximum number of instances in which marine mammals would be reasonably
expected to incur auditory and/or non-auditory injury, and we have
analyzed them accordingly.
If a marine mammal is able to approach a surface vessel within the
distance necessary to incur auditory injury in spite of the mitigation
measures, the likely speed of the vessel (nominally 10-15 kn (18.5-27.8
km/hr)) and relative motion of the vessel would make it very difficult
for the animal to remain in range long enough to accumulate enough
energy to result in more than a mild case of auditory injury. As
discussed previously in relation to TTS, the likely consequences to the
health of an individual that incurs auditory injury can range from mild
to more serious and is dependent upon the degree of auditory injury and
the frequency band associated with auditory injury. The majority of any
auditory injury incurred as a result of exposure to Navy sources would
be expected to be in the 2-20 kHz range (resulting from the most
powerful hull-mounted sonar) and could overlap a small portion of the
communication frequency range of many odontocetes, whereas other marine
mammal groups have communication calls at lower frequencies. Because of
the broadband nature of explosives, auditory injury incurred from
exposure to explosives would occur over a lower, but wider, frequency
range. Permanent loss of some degree of hearing is a normal occurrence
for older animals, and many animals are able to compensate for the
shift, both in old age or at younger ages as the result of stressor
exposure. While a small loss of hearing sensitivity may include some
degree of energetic costs for compensating or may mean some small loss
of opportunities or detection capabilities, at the expected scale it
would be unlikely to impact behaviors, opportunities, or detection
capabilities to a degree that would interfere with reproductive success
or survival.
The Action Proponents implement mitigation measures (described in
the Proposed Mitigation Measures section) during explosive activities,
including delaying detonations when a marine mammal is observed in the
mitigation zone. Nearly all explosive events would occur during
daylight hours thereby improving the sightability of marine mammals and
mitigation effectiveness. Observing for marine mammals during the
explosive activities would include visual and passive acoustic
detection methods (the latter when they are available and part of the
activity) before the activity begins, in order to cover the mitigation
zones that can range from 200 yd (183 m) to 2,500 yd (2,286 m)
depending on the source (e.g., explosive sonobuoy, explosive torpedo,
explosive bombs), and 2.5 nmi (4.6 km) for sinking exercises (see table
60 through table 69).
The type and amount of take by Level A harassment are indicated for
all species and species groups in table 89, table 91, table 93, table
95, table 97, and table 99. Generally speaking, non-auditory injuries
from explosives could range from minor lung injuries (which is the most
sensitive organ and first to be affected) that consist of some short-
term reduction of health and fitness immediately following the injury
that heals quickly and will not have any discernible long-term effects,
up to more impactful permanent injuries across multiple organs that may
cause health problems and negatively impact reproductive success (i.e.,
increase the time between pregnancies or even render reproduction
unlikely) but fall just short of a ``serious injury'' by virtue of the
fact that the animal is not expected to die. Nonetheless, due to the
Navy's mitigation and detection capabilities, we would not expect
marine mammals to typically be exposed to a more severe blast located
closer to the source--so the impacts likely would be less severe. In
addition, most non-auditory injuries and mortalities or serious
injuries are predicted for stocks with medium to large group sizes,
mostly delphinids, which increases sightability. It is still difficult
to evaluate how these injuries may or may not impact an animal's
fitness; however, these effects are only seen in limited numbers
(single digits for all but three stocks) and mostly in species of
moderate, high, and very high abundances. In short, it is unlikely that
any, much less all, of the limited number of injuries accrued to any
one stock would result in reduced reproductive success of any
individuals; even if a few injuries did result in reduced reproductive
success of individuals, the status of the affected stocks are such that
it would not be expected to adversely impact rates of reproduction (and
auditory injury of the low severity anticipated here is not expected to
affect the survival of any individual marine mammals).
Serious Injury and Mortality
NMFS is authorizing a very limited number of serious injuries or
mortalities that could occur in the event of a vessel strike or as a
result of marine mammal exposure to explosive detonations. We note here
that the takes from potential vessel strikes or explosive exposures
enumerated below could result in non-serious injury, but their worst
potential outcome (i.e., mortality) is analyzed for the purposes of the
negligible impact determination.
The MMPA requires that PBR be estimated in SARs and that it be used
in applications related to the management of take incidental to
commercial fisheries (i.e., the take reduction planning process
described in section 118 of the MMPA and the determination of whether a
stock is ``strategic'' as defined in section 3 of the MMPA). While
nothing in the statute requires the application of PBR outside the
management of commercial fisheries interactions with marine mammals,
NMFS recognizes that as a quantitative metric, PBR may be useful as a
consideration when evaluating the impacts of other human-caused
activities on marine mammal stocks. Outside the commercial fishing
context, and in consideration of all known human-caused mortality, PBR
can help inform the potential effects of M/SI requested to be
authorized under section 101(a)(5)(A) of the MMPA. As noted by NMFS and
the U.S. FWS in our implementing regulations for the 1986 amendments to
the MMPA (54 FR 40341, September 29, 1989), the Services consider many
factors, when available, in making a negligible impact determination,
including, but not limited to, the status of the species or stock
relative to OSP (if known); whether the recruitment rate for the
species or stock is increasing, decreasing, stable, or unknown; the
size and distribution of the population; and existing impacts and
environmental conditions. In this multi-factor analysis, PBR can be a
useful indicator for when, and to what extent, the agency should take
an especially close look at the circumstances associated with the
potential mortality, along with any other factors that could influence
annual rates of recruitment or survival.

[[Page 32285]]

Below we describe how PBR is considered in NMFS M/SI analysis.
Please see the 2020 Northwest Training and Testing Final Rule (85 FR
72312, November 12, 2020) for a background discussion of PBR and how it
was adopted for use authorizing incidental take under MMPA section
101(a)(5)(A) for specified activities such as the Action Proponent's
training and testing in the HCTT Study Area.
When considering PBR during evaluation of effects of M/SI under
MMPA section 101(a)(5)(A), we utilize a two-tiered analysis for each
stock for which M/SI is proposed for authorization:
Tier 1: Compare the total human-caused average annual M/SI estimate
from all sources, including the M/SI proposed for authorization from
the specific activity, to PBR. If the total M/SI estimate is less than
or equal to PBR, then the specific activity is considered to have a
negligible impact on that stock. If the total M/SI estimate (including
from the specific activity) exceeds PBR, conduct the Tier 2 analysis.
Tier 2: Evaluate the estimated M/SI from the specified activity
relative to the stock's PBR. If the M/SI from the specified activity is
less than or equal to 10 percent of PBR and other major sources of
human-caused mortality have mitigation in place, then the individual
specified activity is considered to have a negligible impact on that
stock. If the estimate exceeds 10 percent of PBR, then, absent other
mitigating factors, the specified activity could be considered likely
to have a non-negligible impact on that stock and additional analysis
is necessary.
Additional detail regarding the two tiers of the evaluation are
provided below.
As indicated above, the goal of the Tier 1 assessment is to
determine whether total annual human-caused mortality, including from
the specified activity, would exceed PBR. To aid in the Tier 1
evaluation and get a clearer picture of the amount of annual M/SI that
remains without exceeding PBR, for each species or stock, we first
calculate a ``residual PBR,'' which equals PBR minus the ongoing annual
human-caused M/SI (i.e., Residual PBR = PBR-(annual M/SI estimate from
the SAR + other M/SI authorized under section 101(a)(5)(A) of the
MMPA). If the ongoing human-caused M/SI from other sources does not
exceed PBR, then residual PBR is a positive number, and we consider how
the proposed authorized incidental M/SI from the specified activities
being evaluated compares to residual PBR using the Tier 1 framework in
the following paragraph. If the ongoing anthropogenic mortality from
other sources already exceeds PBR, then residual PBR is a negative
number and we move to the Tier 2 discussion further below to consider
the M/SI from the specific activities.
To reiterate, the Tier 1 analysis overview in the context of
residual PBR, if the M/SI from the specified activity does not exceed
PBR, the impacts of the authorized M/SI on the species or stock are
generally considered to be negligible. As a simplifying analytical tool
in the Tier 1 evaluation, we first consider whether the M/SI from the
specified activities could cause incidental M/SI that is less than 10
percent of residual PBR, which we consider an ``insignificance
threshold.'' If so, we consider M/SI from the specified activities to
represent an insignificant incremental increase in ongoing
anthropogenic M/SI for the marine mammal stock in question that alone
will clearly not adversely affect annual rates of recruitment and
survival and for which additional analysis or discussion of the
anticipated M/SI is not required because the negligible impact standard
clearly will not be exceeded on that basis alone.
When the M/SI from the specified activity is above the
insignificance threshold in the Tier 1 evaluation, it does not indicate
that the M/SI associated with the specified activities is necessarily
approaching a level that would exceed negligible impact. Rather, it is
used as a cue to look more closely if and when the M/SI for the
specified activity approaches residual PBR, as it becomes increasingly
necessary (the closer the M/SI from the specified activity is to 100
percent residual PBR) to carefully consider whether there are other
factors that could affect reproduction or survival, such as take by
Level A and/or Level B harassment that has been predicted to impact
reproduction or survival of individuals, or other considerations such
as information that illustrates high uncertainty involved in the
calculation of PBR for some stocks. Recognizing that the impacts of
harassment of any authorized incidental take (by Level A or Level B
harassment from the specified activities) would not combine with the
effects of the authorized M/SI to adversely affect the stock through
effects on recruitment or survival, if the proposed authorized M/SI for
the specified activity is less than residual PBR, the M/SI, alone,
would be considered to have a negligible impact on the species or
stock. If the proposed authorized M/SI is greater than residual PBR,
then the assessment should proceed to Tier 2.
For the Tier 2 evaluation, recognizing that the total annual human-
caused M/SI exceeds PBR, we consider whether the incremental effects of
the proposed authorized M/SI for the specified activity, specifically,
would be expected to result in a negligible impact on the affected
species or stocks. For the Tier 2 assessment, consideration of other
factors (positive or negative), including those described above (e.g.,
the certainty in the data underlying PBR and the impacts of any
harassment authorized for the specified activity), as well as the
mitigation in place to reduce M/SI from other activities is especially
important to assessing the impacts of the M/SI from the specified
activity on the species or stock. PBR is a conservative metric and not
sufficiently precise to serve as an absolute predictor of population
effects upon which mortality caps would appropriately be based. For
example, in some cases stock abundance (which is one of three key
inputs into the PBR calculation) is underestimated because marine
mammal survey data within the U.S. EEZ are used to calculate the
abundance even when the stock range extends well beyond the U.S. EEZ.
An underestimate of abundance could result in an underestimate of PBR.
Alternatively, we sometimes may not have complete M/SI data beyond the
U.S. EEZ to compare to PBR, which could result in an overestimate of
residual PBR. The accuracy and certainty around the data that feed any
PBR calculation, such as the abundance estimates, must be carefully
considered to evaluate whether the calculated PBR accurately reflects
the circumstances of the particular stock.
As referenced above, in some cases the ongoing human-caused
mortality from activities other than those being evaluated already
exceeds PBR and, therefore, residual PBR is negative. In these cases,
any additional mortality, no matter how small, and no matter how small
relative to the mortality caused by other human activities, would
result in greater exceedance of PBR. PBR is helpful in informing the
analysis of the effects of mortality on a species or stock because it
is important from a biological perspective to be able to consider how
the total mortality in a given year may affect the population. However,
section 101(a)(5)(A) of the MMPA indicates that NMFS shall authorize
the requested incidental take from a specified activity if we find that
``the total of such taking [i.e., from the specified activity] will
have a negligible impact on such species or stock.'' In other words,
the task under

[[Page 32286]]

the statute is to evaluate the impact of the applicant's anticipated
take on the species or stock, not the impact of take by other entities.
Neither the MMPA nor NMFS' implementing regulations call for
consideration of other unrelated activities and their impacts on the
species or stock.
Accordingly, we may find that the impacts of the taking from the
specified activity may (alone) be negligible even when total human-
caused mortality from all activities exceeds PBR (in the context of a
particular species or stock). Specifically, where the authorized M/SI
would be less than or equal to 10 percent of PBR and management
measures are being taken to address M/SI from the other contributing
activities (i.e., other than the specified activities covered by the
incidental take authorization under consideration), the impacts of the
authorized M/SI would be considered negligible. In addition, we must
also still determine that any impacts on the species or stock from
other types of take (i.e., harassment) caused by the applicant do not
combine with the impacts from mortality or serious injury addressed
here to result in adverse effects on the species or stock through
effects on annual rates of recruitment or survival.
As noted above, while PBR is useful in informing the evaluation of
the effects of M/SI in MMPA section 101(a)(5)(A) determinations, it is
one consideration to be assessed in combination with other factors and
is not determinative. For example, as explained above, the accuracy and
certainty of the data used to calculate PBR for the species or stock
must be considered. And we reiterate the considerations discussed above
for why it is not appropriate to consider PBR an absolute cap in the
application of this guidance. Accordingly, we use PBR as a trigger for
concern while also considering other relevant factors to provide a
reasonable and appropriate means of evaluating the effects of potential
mortality on rates of recruitment and survival, while acknowledging
that it is possible for total human-caused M/SI to exceed PBR (or for
the M/SI from the specified activity to exceed 10 percent of PBR in the
case where other human-caused mortality is exceeding PBR, as described
in the last paragraph) by some small amount and still make a negligible
impact determination under MMPA section 101(a)(5)(A).
We note that on June 17, 2020, NMFS finalized Procedure 02-204-02,
Criteria for Determining Negligible Impact under MMPA section
101(a)(5)(E) (see https://www.fisheries.noaa.gov/national/laws-policies/protected-resources-policy-directives). The guidance
explicitly notes the differences in the negligible impact
determinations required under section 101(a)(5)(E), as compared to
sections 101(a)(5)(A) and 101(a)(5)(D), and specifies that the
procedure in that document is limited to how the agency conducts
negligible impact analyses for commercial fisheries under section
101(a)(5)(E). In this proposed rule, NMFS has described its method for
considering PBR to evaluate the effects of potential mortality in the
negligible impact analysis. NMFS has reviewed the 2020 guidance and
determined that our consideration of PBR in the evaluation of mortality
as described above and in the proposed rule remains appropriate for use
in the negligible impact analysis for the Action proponent's activities
under section 101(a)(5)(A).
Our evaluation of the M/SI for each of the species and stocks for
which mortality or serious injury could occur follows.
We first consider maximum potential incidental M/SI from the vessel
strike analysis for the affected large whales (table 87) and from the
Action Proponents' explosive detonations for the affected small
cetaceans and pinnipeds (table 88) in consideration of NMFS' threshold
for identifying insignificant M/SI take. By considering the maximum
potential incidental M/SI in relation to PBR and ongoing sources of
anthropogenic mortality, as described above, we begin our evaluation of
whether the potential incremental addition of M/SI through vessel
strikes and explosive detonations may affect the species' or stocks'
annual rates of recruitment or survival. We also consider the
interaction of those mortalities with incidental taking of that species
or stock by harassment pursuant to the specified activity.
Based on the methods discussed previously, NMFS is proposing to
authorize seven mortalities of large whales due to vessel strike over
the course of the 7-year rule, five by the Navy and two by the Coast
Guard (table 87). Across the 7-year duration of the rule, four takes by
mortality (annual average of 0.57 takes) of fin whale (CA/OR/WA stock)
could occur and are proposed for authorization; three takes by
mortality (annual average of 0.43 takes) of gray whale (Eastern North
Pacific stock) and humpback whale (Hawaii stock) could occur and are
proposed for authorization; two takes by mortality (annual average of
0.29 takes) of blue whale (Eastern North Pacific stock), sei whale
(Eastern North Pacific), and humpback whale (Mainland Mexico-CA/OR/WA
and Central America/Southern Mexico-CA/OR/WA stocks (Mexico and Central
America DPSs, respectively)) could occur and are proposed for
authorization; one take by mortality (annual average of 0.14 takes) of
the Hawaii stock of sperm whale could occur and is proposed for
authorization. To calculate the annual average of M/SI by vessel
strike, we divided the 7-year proposed take by serious injury or
mortality by seven.

[[Page 32287]]

Table 87--Summary Information Related to Mortalities Requested for Vessel Strike,
2025-2032
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Fisheries Recent UME
interactions (Y/N); Annual 7-Year
(Y/N); Annual M/ NWTT Potential Residual number of Annual 7-Year proposed proposed Total Total 7-
Stock Total annual rate SI due to authorized biological PBR (PBR strandings, proposed proposed authorized authorized annual year
Common name Stock abundance annual M/ of M/SI vessel take removal minus year authorized authorized take take proposed proposed
SI \a\ from collision (annual) (PBR) annual M/ declared take take (Coast (Coast authorized authorized
fisheries SI) (since (Navy) (Navy) Guard) Guard) take take
interactions 2014)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale............................ Eastern North Pacific *. 3,233 >=18.6 Y; >=0.61 0.6 0 4.1 -14.5 N 0.14 1 0.14 1 0.29 2
Fin whale............................. California/Oregon/ 12,304 >=43.4 Y; >=0.41 6.45 0.29 80 36.31 N 0.43 3 0.14 1 0.57 4
Washington *.
Humpback whale........................ Mainland Mexico-- 3,741 22 Y; 11.4 2.6 0.29 b 43 20.71 N 0.14 1 0.14 1 0.29 2
California-Oregon-
Washington * \b\.
Humpback whale........................ Central America/Southern 1,603 14.9 Y; 8.1 6.45 0.29 c 3.5 -11.69 N 0.14 1 0.14 1 0.29 2
Mexico--California-
Oregon-Washington * \c\.
Sperm whale........................... Hawai[revaps]iHawai[reva 6,062 0 N; 0 UNK 0 18 18 N 0.14 1 0.00 0 0.14 1
ps]i*.
Gray whale............................ Eastern North Pacific... 26,960 131 Y; 9.3 1.8 0.14 801 669.86 Y; 690; 0.29 2 0.14 1 0.43 3
2019
Humpback whale........................ Hawai[revaps]i \b\...... 11,278 27.09 Y; 8.39 5.4 0.29 b 127 99.62 Y; 52; 2015 0.29 2 0.14 1 0.43 3
Sei whale............................. Eastern North Pacific... 864 0 Unk 0 0 1.25 1.25 N 0.14 1 0.14 1 0.29 2
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Unk = Unknown. N/A = Not Applicable. NMFS is proposing to authorize seven takes by serious injury or mortality by vessel strike total across the 7-year duration of the proposed rule, five takes by the Navy and two takes by the
Coast Guard.
* Stock abundance from NMSDD.
\a\ This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock as indicated in the SAR and includes M/SI from fisheries interactions and other sources.
\b\ In 2022, the Central North Pacific stock of humpback whale was split into the Mainland Mexico-California-Oregon-Washington and Hawaii stocks. The 2020 NWTT final rule (85 FR 72312, November 12, 2020) authorized two takes of the
Central North Pacific stock. Given the stock structure change, NMFS has assumed that the two strikes could occur to either the Mainland Mexico--CA/OR/WA stock or the Hawaii stock.
\c\ The 2020 NWTT final rule (85 FR 72312, November 12, 2020) authorized two takes of the CA/OR/WA stock of humpback whale. Given the stock structure change, NMFS has assumed that the two strikes could occur to the Central America/
Southern Mexico- CA/OR/WA stock.

[[Page 32288]]

The Action Proponents also requested a limited number of takes by
M/SI from explosives. Across the 7-year duration of the rule, NMFS is
proposing to authorize 107 takes by M/SI (annual average of 15.29
takes) of short-beaked common dolphin (CA/OR/WA stock), 27 takes by M/
SI (annual average of 3.86 takes) of California sea lion (U.S. stock),
17 takes by M/SI (annual average of 2.43 takes) of long-beaked common
dolphin (California stock), 7 takes by M/SI (annual average of 1 take)
of harbor seal (California stock), 4 takes by M/SI (annual average of
0.57 takes) of short-finned pilot whale (CA/OR/WA stock), 2 takes by M/
SI (annual average of 0.29 takes) of bottlenose dolphin (Hawaii pelagic
stock), Pacific white-sided dolphin (CA/OR/WA stock), pantropical
spotted dolphin (Baja California Peninsula Mexico population), and
rough-toothed dolphin (Hawaii stock), and 1 take by M/SI (annual
average of 0.14 takes) of bottlenose dolphin (O[revaps]ahu stock),
Northern right whale dolphin (CA/OR/WA stock), striped dolphin (CA/OR/
WA stock), and Guadalupe fur seal (Mexico stock) (table 88). To
calculate the annual average of M/SI from explosives, we divided the 7-
year proposed take by serious injury or mortality by seven (table 88),
the same method described for vessel strikes.

[[Page 32289]]

Table 88--Summary Information Related to HCTT Serious Injury or Mortality From Explosives
[2025-2032]
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annual
proposed take 7-Year
Fisheries interactions SWFSC NWTT Residual Recent UME (Y/N); by serious proposed take
Stock Total (Y/N); annual rate of authorized authorized PBR (PBR number of strandings, injury or by serious
Species Stock abundance annual M/ M/SI from fisheries take take PBR minus year declared (since mortality (all injury or Population trend
SI \a\ interactions (annual) (annual) annual M/ 2014) action mortality (all
\b\ \b\ SI) \c\ proponents) action
\d\ proponents)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Short-finned pilot whale.......... California/Oregon/ 836 1.2 Y; 1.2 0.40 0 4.5 2.90 N 0.57 4 Unk.
Washington.
Bottlenose dolphin................ Hawaii Pelagic *..... 25,120 0 N; 0 0 0 158 158 N 0.29 2 Unk.
Bottlenose dolphin................ O[revaps]ahu *....... 113 Unk Unk 0 0 1 Unk N 0.14 1 Unk.
Long-beaked common dolphin........ California *......... 209,100 >=29.7 Y; >=26.5 2.8 0 668 635.5 N 2.43 17 Unk.
Northern right whale dolphin...... California/Oregon/ 68,935 >=6.6 Y; >=6.6 2.20 0 163 154.20 N 0.14 1 Unk.
Washington *.
Pacific white-sided dolphin....... California/Oregon/ 107,775 7 Y; 4 \c\ 8.2 0 279 263.8 N 0.29 2 Unk.
Washington *.
Pantropical spotted dolphin....... Baja California 70,889 Unk Unk 0 0 Unk Unk N 0.29 2 Unk.
Peninsula Mexico *.
Rough-toothed dolphin............. Hawaii *............. 106,193 3.2 Y; 3.2 0 0 511 507.8 N 0.29 2 Unk.
Short-beaked common dolphin....... California/Oregon/ 1,049,117 >=30.5 Y; >=30.5 2.8 0 8,889 8,856 N 15.29 107 Unk, possibly
Washington *. increasing.
Striped dolphin................... California/Oregon/ 160,551 >=4 Y; >=4.0 2.8 0 225 218.2 N 0.14 1 Unk.
Washington *.
California sea lion............... U.S.................. 257,606 >321 Y; >=197 6 0 14,011 13,684 N 3.86 27 Stable.
Guadalupe fur seal................ Mexico............... 63,850 >=10.0 Y; >=7.2 0 0 1,959 1,949 Y; 715; 2015 0.14 1 Increasing.
Harbor seal....................... California........... 30,968 43 Y; 30 \d\ 2.8 0 1,641 1,595 N 1 7 Decreasing.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Unk = Unknown.
* Stock abundance from NMSDD.
\a\ This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock as indicated in the SAR and includes M/SI from fisheries interactions and other sources.
\b\ These columns represents the annual authorized take by mortality in the 2021 LOA for Southwest Fisheries Science Center (SWFSC) Fisheries and Ecosystem Research Activities and the 2020 LOAs for U.S. Navy Northwest Training and
Testing (NWTT) Study Area.
\c\ The SWFSC final rule (86 FR 3840, January 15, 2021) authorizes 41 takes by M/SI of Pacific white-sided dolphin over the 5-year duration of the final rule (i.e., 8.2 annually). These takes could be of multiple stocks; however,
NMFS has conservatively assumed that all of the takes would occur to the CA/OR/WA stock.
\d\ The SWFSC final rule (86 FR 3840, January 15, 2021) authorizes 14 takes by M/SI of harbor seals over the 5-year duration of the final rule (i.e., 2.8 annually). These takes could be of multiple stocks; however, NMFS has
conservatively assumed that all of the takes would occur to the California stock.

[[Page 32290]]

As described above, NMFS M/SI analysis includes two Tiers and our
discussion is organized into sections that mirror that framework, as
applicable. Specifically, we standardly first address stocks analyzed
within Tier 1 (i.e., those for which total known human-caused M/SI is
below PBR (i.e., the M/SI from the specified activity is below residual
PBR)), considering those with proposed M/SI both below and above the
insignificance threshold. Then, if applicable, we discuss stocks for
which total mortality exceeds PBR in a Tier 2 analysis in which we
compare the proposed M/SI of the specified activity alone against PBR
and consider other factors as necessary. Of note, for some stocks total
M/SI is not known, in which case a Tier 1 analysis is not possible and,
therefore, we move directly to a Tier 2 analysis. In rare cases, PBR
itself cannot be calculated, in which case we consider other known
factors and/or surrogate stocks to inform the NID analysis.
Stocks With Total Average Annual Human-Caused M/SI Below PBR (Tier 1)
and Proposed M/SI Is Below the Insignificance Threshold--
As noted above, for a species or stock with M/SI proposed for
authorization less than 10 percent of residual PBR, we consider M/SI
from the specified activities to represent a clearly insignificant
incremental increase in ongoing anthropogenic M/SI that alone (i.e., in
the absence of any other take and barring any other unusual
circumstances) will clearly not adversely affect annual rates of
recruitment and survival. In this case, as shown in table 87 and table
88, the following species or stocks have potential or estimated take by
M/SI from vessel strike and explosives, respectively, and proposed for
authorization below their insignificance threshold: fin whale (CA/OR/WA
stock); humpback whale (Mainland Mexico- CA/OR/WA and Hawaii stocks);
gray whale (Eastern North Pacific stock); sperm whale (Hawaii stock);
bottlenose dolphin (Hawaii pelagic stock); long-beaked common dolphin
(California stock); northern right whale dolphin (CA/OR/WA stock);
Pacific white-sided dolphin (CA/OR/WA stock); rough-toothed dolphin
(Hawaii stock); short-beaked common dolphin (CA/OR/WA stock); striped
dolphin (CA/OR/WA stock); California sea lion (U.S. stock); Guadalupe
fur seal (Mexico stock); and harbor seal (California stock). For the
stocks with authorized M/SI below the insignificance threshold, there
are no other known factors, information, or unusual circumstances that
indicate anticipated M/SI below the insignificance threshold could have
adverse effects on annual rates of recruitment or survival and they are
not discussed further.
Stocks With Total Average Annual Human-Caused M/SI Below PBR (Tier 1)
and Proposed Authorized M/SI Is Above the Insignificance Threshold--
Sei Whale (Eastern North Pacific Stock)
For sei whales (Eastern North Pacific stock), PBR is currently set
at 1.25. The total annual M/SI is 0, yielding a residual PBR of 1.25.
NMFS is proposing to authorize one M/SI for the Navy and one for the
Coast Guard over the 7-year duration of the rule (two total; indicated
as 0.29 annually for the purposes of comparing to PBR and evaluating
overall effects on annual rates of recruitment and survival), which
leaves a PBR remainder of 0.96.
As described above, if the total M/SI estimate is less than or
equal to PBR, which is the case here, then the specific activity is
considered to have a negligible impact on that stock. Although the M/SI
from take proposed here for the specified activity is above the
insignificance threshold, as described above, that does not indicate
that the M/SI associated with the specified activities is necessarily
approaching a level that would exceed negligible impact. Rather, it is
used as a cue to look more closely if and when the M/SI for the
specified activity approaches residual PBR, as it becomes increasingly
necessary (the closer the M/SI from the specified activity is to 100
percent residual PBR) to carefully consider whether there are other
factors that could affect reproduction or survival. Here, the M/SI is
not closely approaching residual PBR (PBR remainder is 0.96) and there
are no other factors that would suggest that the authorized mortality
(alone) would have more than a negligible impact on this stock.
As described previously, NMFS must also ensure that impacts by the
applicant on the species or stock from other types of take (i.e.,
harassment) do not combine with the impacts from mortality to adversely
affect the species or stock via impacts on annual rates of recruitment
or survival, which occurs further below in the Group and Species-
Specific Analyses section.
Additionally of note, management measures are in place to address
M/SI caused by other activities. The Channel Islands NMS staff
coordinates, collects, and monitors whale sightings in and around the
Vessel Speed Reduction (VSR) zones and the Channel Islands NMS region.
The seasonally established Southern California VSR zone spans from
Point Arguello to Dana Point, including the Traffic Separation Schemes
in the Santa Barbara Channel and San Pedro Channel. Vessels transiting
the area from May 1 through December 15, 2025 are recommended to
exercise caution and voluntarily reduce speed to 10 kn (18.5 km per
hour) or less. While the VSR zone is aimed at reducing risk of fatal
vessel strike of blue, humpback, and fin whales, this measure is also
anticipated to reduce risk to sei whales (note, this is an expanded
timeframe from the Whale Advisory Zone discussed in the 2020 HSTT final
rule, which spanned June through November, though the effective period
could change in future years). Channel Island NMS observers collect
information from aerial surveys conducted by NOAA, the U.S. Coast
Guard, California Department of Fish and Game, and U.S. Navy chartered
aircraft. Information on seasonal presence, movement, and general
distribution patterns of large whales is shared with mariners, NMFS
Office of Protected Resources, U.S. Coast Guard, California Department
of Fish and Game, the Santa Barbara Museum of Natural History, the
Marine Exchange of Southern California, and whale scientists. Real time
and historical whale observation data collected from multiple sources
can be viewed on the Point Blue Whale Database.
As stated in the 2023 SAR, the California swordfish drift gillnet
fishery is the most likely U.S. fishery to interact with Eastern North
Pacific sei whales, though there are zero estimated annual takes from
this fishery given no observed entanglements from 1990-2021 across
9,246 observed fishing sets (Carretta et al. (2022)). NMFS established
the Pacific Offshore Cetacean Take Reduction Team (POCTRT) in 1996 and
prepared an associated Plan to reduce the risk of M/SI via fisheries
interactions incidental to the California/Oregon thresher shark/
swordfish drift gillnet fishery. In 1997, NMFS published final
regulations formalizing the requirements of the Plan, including the use
of pingers following several specific provisions and the employment of
Skipper education workshops. While the POCTRT is still active, the
fishery is expected to be phased out entirely by 2027 following passage
of the Driftnet Modernization and Bycatch Reduction Act by the U.S.
Congress in 2022. As such, within 2 years of the effective period of
this proposed rule, NMFS

[[Page 32291]]

does not anticipate mortality from this fishery.
Short-Finned Pilot Whale (CA/OR/WA Stock)
For the CA/OR/WA stock of short-finned pilot whale, PBR is
currently set at 4.5, the total annual M/SI is estimated at 1.2, and
the total annual authorized take from SWFSC Fisheries and Ecosystem
Research Activities in the California Current is 0.4, yielding a
residual PBR of 2.9. NMFS is proposing to authorize four M/SIs (U.S.
Navy only) over the 7-year duration of the rule (indicated as 0.57
annually for the purposes of comparing to PBR and evaluating overall
effects on annual rates of recruitment and survival), which leaves a
PBR remainder of 2.33.
As described above, if the total M/SI estimate is less than or
equal to PBR, which is the case here, then the specific activity is
considered to have a negligible impact on that stock. Although the M/SI
from take proposed here for the specified activity is above the
insignificance threshold, as described above, that does not indicate
that the M/SI associated with the specified activities is necessarily
approaching a level that would exceed negligible impact. Rather, it is
used as a cue to look more closely if and when the M/SI for the
specified activity approaches residual PBR, as it becomes increasingly
necessary (the closer the M/SI from the specified activity is to 100
percent residual PBR) to carefully consider whether there are other
factors that could affect reproduction or survival. Here, the M/SI is
not closely approaching residual PBR (PBR remainder is 2.33) and there
are no other factors that would suggest that the authorized mortality
(alone) would have more than a negligible impact on this stock.
As described previously, NMFS must also ensure that impacts by the
applicant on the species or stock from other types of take (i.e.,
harassment) do not combine with the impacts from mortality to adversely
affect the species or stock via impacts on annual rates of recruitment
or survival, which occurs further below in the Group and Species-
Specific Analyses section.
As reported in the SAR, the total annual M/SI of this stock (1.2)
is from the CA/OR thresher shark/swordfish drift gillnet fishery. NMFS
established the POCTRT in 1996 and prepared an associated Plan to
reduce the risk of M/SI via fisheries interactions incidental to the
California/Oregon thresher shark/swordfish drift gillnet fishery. In
1997, NMFS published final regulations formalizing the requirements of
the Plan, including the use of pingers following several specific
provisions and the employment of Skipper education workshops. While the
POCTRT is still active, the fishery is expected to be phased out
entirely by 2027 following passage of the Driftnet Modernization and
Bycatch Reduction Act by the U.S. Congress in 2022. As such, within 2
years of the effective period of this proposed rule, NMFS does not
anticipate additional mortality from this fishery.
Stocks With Total Average Annual Human-Caused Mortality Above PBR (Tier
2)--
Blue Whale (Eastern North Pacific Stock)
For blue whales (Eastern North Pacific stock), PBR is currently set
at 4.1 and the total annual M/SI is estimated at greater than or equal
to 18.6, yielding a residual PBR of -14.5. NMFS is proposing to
authorize one M/SI for the Navy and one for the Coast Guard over the 7-
year duration of the rule (two total; indicated as 0.29 annually for
the purposes of comparing to PBR and evaluating overall effects on
annual rates of recruitment and survival), which leaves a PBR remainder
of -14.79. However, given that the negligible impact determination is
based on the assessment of take of the activity being analyzed, when
total annual mortality from human activities is higher, but the impacts
from the specific activity being analyzed are very small, NMFS may
still find the incremental impact of the authorized take from a
specified activity is negligible even if total human-caused mortality
exceeds PBR. Specifically, for example, if the authorized mortality is
less than 10 percent of PBR and management measures are being taken to
address serious injuries and mortalities from the other activities
causing mortality (i.e., other than the specified activities covered by
the incidental take authorization in consideration). When those
considerations are applied here, the lethal take proposed for
authorization (0.29 annually) of blue whales from the Eastern North
Pacific stock is less than 10 percent of PBR (which is 4.1), and there
are management measures in place to address M/SI from activities other
than those the Action Proponents are conducting (as discussed below).
Immediately below, we explain the information that supports our finding
that the Action Proponents' M/SI proposed for authorization is not
expected to result in more than a negligible impact on this stock. As
described previously, NMFS must also ensure that impacts by the
applicant on the species or stock from other types of take (i.e.,
harassment) do not combine with the impacts from mortality to adversely
affect the species or stock via impacts on annual rates of recruitment
or survival, which occurs further below in the Group and Species-
Specific Analyses section.
The 2018 draft SAR and the more recent SARs incorporate a method to
estimate annual deaths by vessel strike utilizing an encounter theory
model that combined species distribution models of whale density,
vessel traffic characteristics, and whale movement patterns obtained
from satellite-tagged animals in the region to estimate encounters that
would result in mortality (Rockwood et al. 2017). The model predicts 18
annual mortalities of blue whales from vessel strikes, which, with the
additional M/SI of 1.54 from fisheries interactions, results in the
current estimate of residual PBR being -15.4. Although NMFS' Permits
and Conservation Division in the Office of Protected Resources has
independently reviewed the vessel strike model and its results and
agrees that it is appropriate for estimating blue whale mortality by
vessel strike on the U.S. West Coast, for analytical purposes we also
note that if the historical method were used to predict vessel strike
(i.e., using observed mortality by vessel strike, or 0.6, instead of
18), then total human-caused mortality including the Action Proponents'
potential take would not exceed PBR. We further note that the authors
(Rockwood et al. 2017) do not suggest that vessel strike suddenly
increased to 18 recently. In fact, the model is not specific to a year,
but rather offers a generalized prediction of vessel strike off the
U.S. West Coast. Therefore, if the Rockwood et al. (2017) model is an
accurate representation of vessel strike, then similar levels of vessel
strike have been occurring in past years as well. Put another way, if
the model is correct, for some number of years total-human-caused
mortality has been significantly underestimated and PBR has been
similarly exceeded by a notable amount, and yet, the Eastern North
Pacific stock of blue whales remains stable, nevertheless.
NMFS' 2023 SAR states that the current population trend is unknown,
though there may be evidence of a population size increase since the
1990s. The SAR further cites to Monnahan et al. (2015), which used a
population dynamics model to estimate that the Eastern North Pacific
blue whale population was at 97 percent of carrying capacity in 2013
and to suggest

[[Page 32292]]

that the observed lack of a population increase since the early 1990s
was explained by density dependence, not impacts from vessel strike.
This would mean that this stock of blue whales shows signs of stability
and is not increasing in population size because the population size is
at or nearing carrying capacity for its available habitat. In fact, we
note that this population has maintained this status throughout the
years that the Navy has consistently tested and trained at similar
levels (with similar vessel traffic) in areas that overlap with blue
whale occurrence, which would be another indicator of population
stability.
Monnahan et al. (2015) modeled vessel numbers, vessel strikes, and
the population of the Eastern North Pacific blue whale population from
1905 out to 2050 using a Bayesian framework to incorporate informative
biological information and assign probability distributions to
parameters and derived quantities of interest. The authors tested
multiple scenarios with differing assumptions, incorporated
uncertainty, and further tested the sensitivity of multiple variables.
Their results indicated that there is no immediate threat (i.e.,
through 2050) to the population from any of the scenarios tested, which
included models with 10 and 35 strike mortalities per year. Broadly,
the authors concluded that, unlike other blue whale stocks, the Eastern
North Pacific blue whales have recovered from 70 years of whaling and
are in no immediate threat from vessel strikes. They further noted that
their conclusion conflicts with the depleted and strategic designation
under the MMPA as well as PBR specifically.
As discussed, we also take into consideration management measures
in place to address M/SI caused by other activities. The Channel
Islands NMS staff coordinates, collects, and monitors whale sightings
in and around the VSR zones and the Channel Islands NMS region. Redfern
et al. (2013) note that the most risky area for blue whales is the
Santa Barbara Channel, where shipping lanes intersect with common
feeding areas. The seasonally established Southern California VSR zone
spans from Point Arguello to Dana Point, including the Traffic
Separation Schemes in the Santa Barbara Channel and San Pedro Channel.
Vessels transiting the area from May 1 through December 15, 2025 are
recommended to exercise caution and voluntarily reduce speed to 10 kn
(18.5 km per hour) or less for blue, humpback, and fin whales. Channel
Island NMS observers collect information from aerial surveys conducted
by NOAA, the U.S. Coast Guard, California Department of Fish and Game,
and U.S. Navy chartered aircraft. Information on seasonal presence,
movement, and general distribution patterns of large whales is shared
with mariners, NMFS Office of Protected Resources, U.S. Coast Guard,
California Department of Fish and Game, the Santa Barbara Museum of
Natural History, the Marine Exchange of Southern California, and whale
scientists. Real time and historical whale observation data collected
from multiple sources can be viewed on the Point Blue Whale Database.
In addition to management measures for vessel strike, NMFS is in the
process of developing a new Take Reduction Team to address the
incidental M/SI of humpback and blue whales in several trap/pot
fisheries along the West Coast of the U.S. The Team is expected to be
in place by November 30, 2025. Additional information is available on
NMFS' website at: https://www.fisheries.noaa.gov/west-coast/marine-mammal-protection/west-coast-take-reduction-team
The loss of a male would have far less, if any, effect on
population rates and, absent any information suggesting that one sex is
more likely to be struck than another, we can reasonably assume that
there is a 50 percent chance that each of the two strikes proposed for
authorization by this proposed rulemaking would be a male, thereby
further decreasing the likelihood of impacts on the population rate. In
situations like this where potential M/SI is fractional, consideration
must be given to the lessened impacts anticipated due to the likely
absence of M/SI in 5 or 6 of the 7 years and the fact that each of the
strikes could be a male.
Lastly, we reiterate that PBR is a conservative metric and also not
sufficiently precise to serve as an absolute predictor of population
effects upon which mortality caps would appropriately be based. As
noted above, Wade et al. (1998), authors of the paper from which the
current PBR equation is derived, note that ``[e]stimating incidental
mortality in 1 year to be greater than the PBR calculated from a single
abundance survey does not prove the mortality will lead to depletion;
it identifies a population worthy of careful future monitoring and
possibly indicates that mortality-mitigation efforts should be
initiated.'' The information included here indicates that the current
population trend of this blue whale stock is unknown but likely
approaching carrying capacity and has leveled off because of density-
dependence, not human-caused mortality, in spite of what might be
otherwise indicated from the calculated PBR. Further, potential M/SI
proposed for authorization is below 10 percent of PBR and management
actions are in place to minimize vessel strike from other vessel
activity in one of the highest-risk areas for strikes. Based on the
presence of the factors described above, we do not expect lethal take
from Action Proponents' activities, alone, to adversely affect Eastern
North Pacific blue whales through effects on annual rates of
recruitment or survival. Nonetheless, the fact that total human-caused
mortality exceeds PBR necessitates close attention to the remainder of
the impacts (i.e., harassment) on the Eastern North Pacific stock of
blue whales from the Navy's activities to ensure that the total takes
proposed for authorization have a negligible impact on the species or
stock. Therefore, this information will be considered in combination
with our assessment of the impacts of harassment takes proposed for
authorization in the Group and Species-Specific Analyses section that
follows.
Humpback Whale (Central America/Southern Mexico CA/OR/WA Stock)
For humpback whales (Central America/Southern Mexico CA/OR/WA
stock), PBR is currently set at 3.5, the total annual M/SI is estimated
at greater than or equal to 14.9, and the 2020 NWTT final rule
authorizes 0.29 takes by mortality annually, yielding a residual PBR of
-11.69. NMFS is proposing to authorize one M/SI for the Navy and one
for the Coast Guard over the 7-year duration of the rule (two total;
indicated as 0.29 annually for the purposes of comparing to PBR and
evaluating overall effects on annual rates of recruitment and
survival), which leaves a PBR remainder of -11.98.
However, given that the negligible impact determination is based on
the assessment of take of the activity being analyzed, when total
annual mortality from human activities is higher, but the impacts from
the specific activity being analyzed are very small, NMFS may still
find the incremental impact of the authorized take from a specified
activity is negligible even if total human-caused mortality exceeds
PBR. Specifically, for example, if the authorized mortality is less
than 10 percent of PBR and management measures are being taken to
address serious injuries and mortalities from the other activities
causing mortality (i.e., other than the specified activities covered by
the incidental take authorization in consideration). When those

[[Page 32293]]

considerations are applied here, the lethal take proposed for
authorization (0.29 annually) of humpback whales from the Central
America/Southern Mexico CA/OR/WA stock is less than 10 percent of PBR
(which is 3.5), and there are management measures in place to address
M/SI from activities other than those the Action Proponents are
conducting (as discussed below). Immediately below, we explain the
information that supports our finding that the Action Proponents' M/SI
proposed for authorization is not expected to result in more than a
negligible impact on this stock. As described previously, NMFS must
also ensure that impacts by the applicant on the species or stock from
other types of take (i.e., harassment) do not combine with the impacts
from mortality to adversely affect the species or stock via impacts on
annual rates of recruitment or survival, which occurs further below in
the Group and Species-Specific Analyses section.
The 2018 draft SAR and the more recent SARs rely on a new method to
estimate annual deaths by vessel strike utilizing an encounter theory
model that combined species distribution models of whale density,
vessel traffic characteristics, and whale movement patterns obtained
from satellite-tagged animals in the region to estimate encounters that
would result in mortality (Rockwood et al. 2017). The model predicts 22
annual mortalities of humpback whales from vessel strikes, and the SAR
attributes 6.45 of those strikes to the Central America/Southern
Mexico-CA/OR/WA stock. With the additional M/SI of 8.1 from fisheries
interactions, 0.35 from marine debris, recreational, and tribal
fisheries, and 0.29 from vessel strike authorized in the NWTT final
rule, results in the current estimate of residual PBR being -11.69.
Although NMFS' Permits and Conservation Division in the Office of
Protected Resources has independently reviewed the vessel strike model
and its results and agrees that it is appropriate for estimating
humpback whale mortality by vessel strike on the U.S. West Coast, for
analytical purposes we also note that if the historical method were
used to predict vessel strike (i.e., using observed mortality by vessel
strike, or 0.6, instead of 18), then total human-caused mortality
including the Action Proponents' potential take would not exceed PBR.
We further note that the authors (Rockwood et al. 2017) do not suggest
that vessel strike suddenly increased to 22 recently. In fact, the
model is not specific to a year, but rather offers a generalized
prediction of vessel strike off the U.S. West Coast. Therefore, if the
Rockwood et al. (2017) model is an accurate representation of vessel
strike, then similar levels of vessel strike have been occurring in
past years as well. Put another way, if the model is correct, for some
number of years total-human-caused mortality has been significantly
underestimated and PBR has been similarly exceeded by a notable amount,
and yet, the Central America/Southern Mexico-CA/OR/WA stock of humpback
whales is increasing nevertheless.
As discussed, we also take into consideration management measures
in place to address M/SI caused by other activities. The Channel
Islands NMS staff coordinates, collects, and monitors whale sightings
in and around the VSR zones and the Channel Islands NMS region. The
seasonally established Southern California VSR zone spans from Point
Arguello to Dana Point, including the Traffic Separation Schemes in the
Santa Barbara Channel and San Pedro Channel. Vessels transiting the
area from May 1 through December 15, 2025 are recommended to exercise
caution and voluntarily reduce speed to 10 kn (18.5 km per hour) or
less for blue, humpback, and fin whales. Channel Island NMS observers
collect information from aerial surveys conducted by NOAA, the U.S.
Coast Guard, California Department of Fish and Game, and U.S. Navy
chartered aircraft. Information on seasonal presence, movement, and
general distribution patterns of large whales is shared with mariners,
NMFS Office of Protected Resources, U.S. Coast Guard, California
Department of Fish and Game, the Santa Barbara Museum of Natural
History, the Marine Exchange of Southern California, and whale
scientists. Real time and historical whale observation data collected
from multiple sources can be viewed on the Point Blue Whale Database.
In addition to management measures for vessel strike, NMFS is in the
process of developing a new Take Reduction Team to address the
incidental M/SI of humpback and blue whales in several trap/pot
fisheries along the West Coast of the U.S. The Team is expected to be
in place by November 30, 2025. Additional information is available on
NMFS' website at: https://www.fisheries.noaa.gov/west-coast/marine-mammal-protection/west-coast-take-reduction-team.
The loss of a male would have far less, if any, effect on
population rates and absent any information suggesting that one sex is
more likely to be struck than another, we can reasonably assume that
there is a 50 percent chance that each of the two strikes proposed for
authorization by this proposed rulemaking would be a male, thereby
further decreasing the likelihood of impacts on the population rate. In
situations like this where potential M/SI is fractional, consideration
must be given to the lessened impacts anticipated due to the likely
absence of M/SI in 5 or 6 of the 7 years and the fact that each of the
strikes could be a male.
Lastly, we reiterate that PBR is a conservative metric and also not
sufficiently precise to serve as an absolute predictor of population
effects upon which mortality caps would appropriately be based. As
noted above, Wade et al. (1998), authors of the paper from which the
current PBR equation is derived, note that ``[e]stimating incidental
mortality in 1 year to be greater than the PBR calculated from a single
abundance survey does not prove the mortality will lead to depletion;
it identifies a population worthy of careful future monitoring and
possibly indicates that mortality-mitigation efforts should be
initiated.'' Further, potential M/SI proposed for authorization is
below 10 percent of PBR and management actions are in place to minimize
vessel strike from other vessel activity and efforts are underway to
minimize M/SI from trap/pot fisheries along the U.S. West Coast. Based
on the presence of the factors described above, we do not expect lethal
take from Action Proponents' activities, alone, to adversely affect
Central America/Southern Mexico-CA/OR/WA humpback whales through
effects on annual rates of recruitment or survival. Nonetheless, the
fact that total human-caused mortality exceeds PBR necessitates close
attention to the remainder of the impacts (i.e., harassment) on the
Central America/Southern Mexico-CA/OR/WA stock of humpback whales from
the Action Proponents' activities to ensure that the total takes
proposed for authorization have a negligible impact on the species or
stock. Therefore, this information will be considered in combination
with our assessment of the impacts of harassment takes proposed for
authorization in the Group and Species-Specific Analyses section that
follows.
Stocks for Which Total Average Annual Mortality Is Not Known--
Bottlenose Dolphin (O[revaps]ahu Stock)
For bottlenose dolphin (O[revaps]ahu stock), PBR is currently set
at 1. The total annual M/SI is unknown, and therefore a residual PBR
cannot be calculated. NMFS is proposing to authorize one M/SI over the
7-year duration of the rule

[[Page 32294]]

(indicated as 0.14 annually for the purposes of comparing to PBR and
evaluating overall effects on annual rates of recruitment and
survival).
Given that the negligible impact determination is based on the
assessment of take of the activity being analyzed, even if total annual
mortality from human activities is higher, but the impacts from the
specific activity being analyzed are very small, NMFS may still find
the incremental impact of the authorized take from a specified activity
is to be negligible even if total human-caused mortality exceeds PBR.
As such, the incremental impact of the authorized take from a specified
activity may also be negligible where total annual M/SI is unknown. An
unknown total annual M/SI is a cue to look more closely if and when the
M/SI for the specified activity approaches PBR (e.g., consider whether
there are mitigation measures in place for other potential sources of
M/SI), as it becomes increasingly necessary (the closer the M/SI from
the specified activity is to PBR) to carefully consider whether there
are other factors that could affect reproduction or survival. Here, the
M/SI proposed for authorization is 0.14 annually, which does not
closely approach PBR (PBR is 1.0), there are management measures in
place to address M/SI from activities other than those the Action
Proponents are conducting (as discussed below), and there are no other
factors that would suggest that the authorized mortality (alone) would
have more than a negligible impact on this stock. Immediately below, we
explain the information that supports our finding that the Action
Proponents' M/SI proposed for authorization is not expected to result
in more than a negligible impact on this stock. As described
previously, NMFS must also ensure that impacts by the applicant on the
species or stock from other types of take (i.e., harassment) do not
combine with the impacts from mortality to adversely affect the species
or stock via impacts on annual rates of recruitment or survival, which
occurs further below in the Group and Species-Specific Analyses
section.
As reported in the SAR, while information about fishery-related
mortality is limited for this stock, Hawaii fisheries use gear types
that cause mortality and serious injury to marine mammals in other U.S.
fisheries, including gillnets and hook-and-line, and mortality reports
indicate that nearshore fisheries are a risk for bottlenose dolphins in
Hawaii. However, gillnetting around Maui and much of O[revaps]ahu is
banned by state regulation, and in areas where gillnetting is
permitted, fishermen are required to monitor their gillnets for bycatch
every 30 minutes.
In this case, 0.14 M/SI means one mortality in 1 of the 7 years and
zero mortalities in 6 of those 7 years. Therefore, the Action
Proponents would not be contributing to the total human-caused
mortality at all in 6 of the 7, or 85.7 percent, of the years covered
by this proposed rulemaking. That means that even if an O[revaps]ahu
bottlenose dolphin were to be lethally taken from explosives, in 6 of
the 7 years, there could be no effect on annual rates of recruitment or
survival from Navy-caused M/SI. Additionally, the loss of a male would
have far less, if any, effect on population rates and absent any
information suggesting that one sex is more likely to be struck than
another, we can reasonably assume that there is a 50 percent chance
that the single mortality proposed for authorization by this proposed
rulemaking would be a male, thereby further decreasing the likelihood
of impacts on the population rate. In situations like this where
potential M/SI is fractional, consideration must be given to the
lessened impacts anticipated due to the absence of M/SI in 6 of the 7
years and the fact that the single mortality could be a male. Lastly,
we reiterate that PBR is a conservative metric and also not
sufficiently precise to serve as an absolute predictor of population
effects upon which mortality caps would appropriately be based. This is
especially important given the minor difference between zero and one
across the 7-year period covered by this proposed rulemaking, which is
the smallest distinction possible when considering mortality. As noted
above, Wade et al. (1998), authors of the paper from which the current
PBR equation is derived, note that ``[e]stimating incidental mortality
in 1 year to be greater than the PBR calculated from a single abundance
survey does not prove the mortality will lead to depletion; it
identifies a population worthy of careful future monitoring and
possibly indicates that mortality-mitigation efforts should be
initiated.'' Further, management actions are in place that minimize
fishery interactions. Based on the presence of the factors described
above, we do not expect lethal take from the Action Proponents'
activities, alone, to adversely affect O[revaps]ahu bottlenose dolphins
through effects on annual rates of recruitment or survival.
Nonetheless, the fact that total human-caused mortality is unknown, and
PBR is low, necessitates close attention to the remainder of the
impacts (i.e., harassment) on the O[revaps]ahu stock of bottlenose
dolphins from the Action Proponents' activities to ensure that the
total takes proposed for authorization have a negligible impact on the
species or stock. Therefore, this information will be considered in
combination with our assessment of the impacts of authorized harassment
takes in the Group and Species-Specific Analyses section that follows.
Stocks for Which PBR Is Unknown--
Pantropical Spotted Dolphin (Baja California Peninsula Mexico
Population)
The Baja California Peninsula Mexico population of pantropical
spotted dolphins are not a NMFS-managed stock, and therefore, PBR and
annual M/SI metrics are not available. NMFS is proposing to authorize
two M/SIs over the 7-year duration of the rule (indicated as 0.29
annually for the purposes of evaluating overall effects on annual rates
of recruitment and survival).
Immediately below, we explain the information that supports our
finding that the Action Proponents' M/SI proposed for authorization is
not expected to result in more than a negligible impact on this stock.
As described previously, NMFS must also ensure that impacts by the
applicant on the species or stock from other types of take (i.e.,
harassment) do not combine with the impacts from mortality to adversely
affect the species or stock via impacts on annual rates of recruitment
or survival, which occurs further below in the Group and Species-
Specific Analyses section.
Given that this is not a NMFS-managed stock, some metrics are not
available for this population, including PBR. PBR values are calculated
by NMFS as the level of annual removal from a stock that will allow
that stock to equilibrate within OSP at least 95 percent of the time,
and is the product of factors relating to the minimum population
estimate of the stock (Nmin), the productivity rate of the
stock at a small population size, and a recovery factor. The
productivity rate is estimated as one-half of the estimated or
theoretical maximum rate of population growth for the stock if it were
small. In this case, NMFS estimates the productivity rate to be one
half the default maximum net growth rate for cetaceans (one half of 4
percent). Recovery factors range from 0.1 to 1, with smaller factors
applied to more at-risk species. Given the unknowns of this population
NMFS used 0.1. Nmin is not

[[Page 32295]]

available, and therefore, NMFS relies on the NMSDD abundance estimate
of 70,889 to estimate PBR. As such, using the NMSDD abundance estimate,
PBR is estimated to be 141.78 (70,889 x (0.5 x 4 percent) x (0.1). (Of
note, if PBR was calculating using an estimated Nmin of half
of the NMSDD abundance estimate (35,445), PBR would be 70.89.)
Given that the negligible impact determination is based on the
assessment of take of the activity being analyzed, even if total annual
mortality from human activities is higher, but the impacts from the
specific activity being analyzed are very small, NMFS may still find
the incremental impact of the authorized take from a specified activity
is to be negligible even if total human-caused mortality exceeds PBR.
As such, the incremental impact of the authorized take from a specified
activity may also be negligible where total annual M/SI is unknown. An
unknown total annual M/SI is a cue to look more closely if and when the
M/SI for the specified activity approaches PBR (e.g., consider whether
there are mitigation measures in place for other potential sources of
M/SI), as it becomes increasingly necessary (the closer the M/SI from
the specified activity is to PBR) to carefully consider whether there
are other factors that could affect reproduction or survival. Here, the
M/SI proposed for authorization is 0.29 annually, which does not
closely approach our PBR estimate above (PBR is estimated as 141.78,
potentially as low as 70.89), and there are no other factors that would
suggest that the authorized mortality (alone) would have more than a
negligible impact on this stock. Immediately below, we explain the
information that supports our finding that the Action Proponents' M/SI
proposed for authorization is not expected to result in more than a
negligible impact on this stock. As described previously, NMFS must
also ensure that impacts by the applicant on the species or stock from
other types of take (i.e., harassment) do not combine with the impacts
from mortality to adversely affect the species or stock via impacts on
annual rates of recruitment or survival, which occurs further below in
the Group and Species-Specific Analyses section.
The loss of a male would have far less, if any, effect on
population rates and absent any information suggesting that one sex is
more likely to be struck than another, we can reasonably assume that
there is a 50 percent chance that any single mortality proposed for
authorization by this proposed rulemaking would be a male, thereby
further decreasing the likelihood of impacts on the population rate. In
situations like this where potential M/SI is fractional, consideration
must be given to the lessened impacts anticipated due to the absence of
M/SI in 5 or 6 of the 7 years and the fact that any single mortality
could be a male.
Based on the presence of the factors described above, we do not
expect lethal take from the Action Proponents' activities, alone, to
adversely affect the Baja California Peninsula Mexico population of
pantropical spotted dolphins through effects on annual rates of
recruitment or survival. Nonetheless, the fact that total human-caused
mortality is unknown necessitates close attention to the remainder of
the impacts (i.e., harassment) on the Baja California Peninsula Mexico
population of pantropical spotted dolphins from the Action Proponents'
activities to ensure that the total takes proposed for authorization
have a negligible impact on the species or stock. Therefore, this
information will be considered in combination with our assessment of
the impacts of authorized harassment takes in the Group and Species-
Specific Analyses section that follows.

Group and Species-Specific Analyses

In this section, we build on the general analysis that applies to
all marine mammals in the HCTT Study Area from the previous sections.
We first include information and analysis that applies to mysticetes
or, separately, odontocetes or pinnipeds, and then within those three
sections, more specific information that applies to smaller groups,
where applicable, and the affected species or stocks. The specific
authorized take numbers are also included in the analyses below, and so
here we provide some additional context and discussion regarding how we
consider the authorized take numbers in those analyses.
The maximum amount and type of incidental take of marine mammals
reasonably likely to occur and therefore proposed to be authorized from
exposures to sonar and other active acoustic sources and explosions
during the 7-year activity period are shown in table 37, table 38,
table 39, and table 40, and the subset attributable to ship shock
trials is included in table 49.
In the discussions below, the estimated takes by Level B harassment
represent instances of take, not the number of individuals taken (the
much lower and less frequent Level A harassment takes are far more
likely to be associated with separate individuals), and in some cases
individuals may be taken more than one time. As part of our evaluation
of the magnitude and severity of impacts to marine mammal individuals
and the species, and specifically in an effort to better understand the
degree to which the modeled and estimated takes likely represent
repeated takes of the individuals of a given species/stock, we consider
the total annual numbers of take by harassment (auditory injury, non-
auditory injury, TTS, and behavioral disturbance) for species or stocks
as compared to their associated abundance estimates--specifically, take
numbers higher than the stock abundance clearly indicate that some
number of individuals are being taken on more than one day in the year,
and broadly higher or lower ratios of take to abundance may reasonably
be considered to equate to higher or lower likelihood of repeated
takes, respectively, other potentially influencing factors being equal.
In addition to the mathematical consideration of estimated take
compared to abundance, we also consider other factors or circumstances
that may influence the likelihood of repeated takes, where known, such
as circumstances where activities resulting in take are focused in an
area and time (e.g., instrumented ranges or a homeport, or long-
duration activities such as MTEs) and/or where the same individual
marine mammals are known to congregate over longer periods of time
(e.g., pinnipeds at a haulout, mysticetes in a known foraging area, or
resident odontocetes with smaller home ranges). Similarly, and all else
being equal, estimated takes that are largely focused in one region
and/or season (see table 89, table 91, table 93, table 95, table 97,
and table 99) may indicate a higher likelihood of repeated takes of the
same individuals.
Occasional, milder behavioral responses are unlikely to cause long-
term consequences for individual animals or populations, and even if
some smaller subset of the takes are in the form of a longer (several
hours or a day) and more severe response, if they are not expected to
be repeated over a comparatively longer duration of sequential days,
impacts to individual fitness are not anticipated. Nearly all studies
and experts agree that infrequent exposures of a single day or less are
unlikely to impact an individual's overall energy budget (Farmer et
al., 2018b; Harris et al., 2018; King et al., 2015; NAS, 2017; New et
al., 2014; Southall et al., 2007; Villegas-Amtmann et al., 2015;
Hoekendijk et al., 2018; Wisniewska et al., 2018; Czapanskiy et al.,
2021; Pirotta, 2022). Generally speaking, and in the case of most

[[Page 32296]]

species impacted by the proposed activities, in the cases where some
number of individuals may reasonably be expected to be taken on more
than one day within a year, that number of days would be comparatively
small and also with no reason to expect that those takes would occur on
sequential days. In the rarer cases of species where individuals might
be expected to be taken on a comparatively higher number of days of the
year and there are reasons to think that these days might be sequential
or clumped together, the likely impacts of this situation are discussed
explicitly in the species discussions.
To assist in understanding what this analysis means, we clarify a
few issues related to estimated takes and the analysis here. An
individual that incurs AUD INJ or TTS may sometimes, for example, also
be subject to behavioral disturbance at the same time. As described
above in this section, the degree of auditory injury, and the degree
and duration of TTS, expected to be incurred from the Navy's activities
are not expected to impact marine mammals such that their reproduction
or survival could be affected. Similarly, data do not suggest that a
single instance in which an animal accrues auditory injury or TTS and
is also subjected to behavioral disturbance would result in impacts to
reproduction or survival. Alternately, we recognize that if an
individual is subjected to behavioral disturbance repeatedly for a
longer duration and on consecutive days, effects could accrue to the
point that reproductive success is impacted. Accordingly, in analyzing
the number of takes and the likelihood of repeated and sequential
takes, we consider the total takes, not just the takes by Level B
harassment by behavioral disturbance, so that individuals potentially
exposed to both threshold shift and behavioral disturbance are
appropriately considered. The number of takes by Level A harassment by
auditory injury are so low (and zero in some cases) compared to
abundance numbers that it is considered highly unlikely that any
individual would be taken at those levels more than once.
Use of sonar and other transducers would typically be transient and
temporary. The majority of acoustic effects to most marine mammal
stocks from sonar and other active sound sources during the specified
military readiness activities would be primarily from anti-submarine
warfare events. On the less severe end, exposure to comparatively lower
levels of sound at a detectably greater distance from the animal, for a
few or several minutes, could result in a behavioral response such as
avoiding an area that an animal would otherwise have moved through or
fed in, or breaking off one or a few feeding bouts. More severe
behavioral effects could occur when an animal gets close enough to the
source to receive a comparatively higher level of sound, is exposed
continuously to one source for a longer time or is exposed
intermittently to different sources throughout a day. Such effects
might result in an animal having a more severe flight response and
leaving a larger area for a day or more or potentially losing feeding
opportunities for a day. However, such severe behavioral effects are
expected to occur infrequently. In addition to the proximity to the
source, the type of activity and the season and location during which
an animal is exposed can inform the impacts. These factors, including
the numbers and types of effects that are estimated in areas known to
be biologically important for certain species are discussed in the
group and species-specific sections, below.
As described in the Proposed Mitigation Measures section, this
proposed rule includes mitigation measures that would reduce the
probability and/or severity of impacts expected to result from acute
exposure to acoustic sources or explosives, vessel strike, and impacts
to marine mammal habitat. Specifically, the Action Proponents would use
a combination of delayed starts, powerdowns, and shutdowns to avoid
mortality or serious injury, minimize the likelihood or severity of AUD
INJ or non-auditory injury, and reduce instances of TTS or more severe
behavioral disturbance caused by acoustic sources or explosives. The
Action Proponents would also implement multiple time/area restrictions
that would reduce take of marine mammals in areas or at times where
they are known to engage in important behaviors, such as calving, where
the disruption of those behaviors would have a higher probability of
resulting in impacts on reproduction or survival of individuals that
could lead to population-level impacts.
These time/area restrictions include a Hawaii Island Marine Mammal
Mitigation Area, a Hawaii 4-Islands Marine Mammal Mitigation Area,
Northern California Large Whale Mitigation Area, Central California
Large Whale Mitigation Area, Southern California Blue Whale Mitigation
Area, California Large Whale Real-Time Notification Mitigation Area,
and San Nicolas Island Pinniped Haulout Mitigation Area as well as
Hawaii Humpback Whale Awareness Messages and California Large Whale
Awareness Messages. The Southern California Blue Whale Mitigation Area
is discussed in the blue whale section below. However, it is important
to note that measures in that area, while developed to protect blue
whales, would also benefit other marine mammals in those areas.
Therefore, they are discussed here also.
Within the Hawaii Island Marine Mammal Mitigation Area, the Action
Proponents must not use more than 300 hours of MF1 surface ship hull-
mounted mid-frequency active sonar or 20 hours of helicopter dipping
sonar (a mid-frequency active sonar source) annually and must not
detonate in-water explosives (including underwater explosives and
explosives deployed against surface targets). Mitigation in this area
is designed to reduce exposure of numerous small and resident marine
mammal populations (including Blainville's beaked whales, bottlenose
dolphins, goose-beaked whales, dwarf sperm whales, false killer whales,
melon-headed whales, pantropical spotted dolphins, pygmy killer whales,
rough-toothed dolphins, short-finned pilot whales, and spinner
dolphins), humpback whales within important seasonal reproductive
habitat, and Hawaiian monk seals within critical habitat, to levels of
sound that have the potential to cause injurious or behavioral impacts.
Within the Hawaii 4-Islands Marine Mammal Mitigation Area, from
November 15-April 15, the Action Proponents must not use MF1 surface
ship hull-mounted mid-frequency active sonar. The Action Proponents
must not detonate in-water explosives (including underwater explosives
and explosives deployed against surface targets) within the mitigation
area (year-round). This mitigation would prevent exposure of humpback
whales in high-density seasonal reproductive habitats (e.g., north of
Maui and Moloka[revaps]i), Main Hawaiian Islands insular false killer
whales in high seasonal occurrence areas, and numerous small and
resident marine mammal populations that occur year-round (including
bottlenose dolphins, pantropical spotted dolphins, and spinner
dolphins, and Hawaiian monk seals) to explosives that have the
potential to cause injury, mortality, or behavioral disturbance, and
would minimize exposure of humpback whales in high-density seasonal
reproductive habitats (e.g., north of Maui and Moloka[revaps]i) and
Main Hawaiian Islands insular false killer whales in high seasonal
occurrence areas to levels of sound that have the potential to cause
injurious or behavioral impacts.

[[Page 32297]]

Within the Northern California Large Whale Mitigation Area, Central
California Large Whale Mitigation Area, and Southern California Blue
Whale Mitigation Area, from June 1-October 31, the Action Proponents
must not use more than 300 hours of MF1 surface ship hull-mounted mid-
frequency active sonar (excluding normal maintenance and systems
checks) total during training and testing within these three areas.
This measure would reduce exposure of blue whales, fin whales, gray
whales, and humpback whales in important seasonal foraging, migratory,
and calving habitats to levels of sound that have the potential to
cause injurious or behavioral impacts. Additionally, during the same
June 1-October 31 period, within the portion of the mitigation area off
San Diego, the Action Proponents must not detonate in-water explosives
(including underwater explosives and explosives deployed against
surface targets) during large-caliber (>=57 mm (2.24 inch)) gunnery,
torpedo, bombing, and missile (including 2.75-inch (7 cm) rockets)
training and testing. This measure would reduce exposure of large
whales within important seasonal foraging habitats to explosives that
have the potential to cause injury, mortality, or behavioral
disturbance.
Within the California Large Whale Real-Time Notification Mitigation
Area, the Action Proponents would issue real-time notifications to
alert Action Proponent vessels operating in the vicinity of large whale
aggregations (four or more whales) sighted within 1 nmi (1.9 km) of an
Action Proponent vessel within an area of the Southern California Range
Complex (between 32-33 degrees North and 117.2-119.5 degrees West).
Lookouts must use the information from the real-time notifications to
inform their visual observations of applicable mitigation zones. The
real-time notification area encompasses the locations of recent (2009,
2021, 2023) vessel strikes, and historic strikes where precise latitude
and longitude were known.
Within the San Nicolas Island Pinniped Haulout Mitigation Area,
Navy personnel must implement multiple measures that would minimize in-
air launch noise and physical disturbance to pinnipeds hauled out on
beaches, as well as to continue assessing baseline pinniped
distribution/abundance and potential changes in pinniped use of these
beaches after launch events.
Last, the Hawaii Humpback Whale Awareness Messages and California
Large Whale Awareness Messages would alert applicable assets (and their
Lookouts) transiting and training or testing in the Hawaii Range
Complex or on the U.S. West Coast to the possible presence of
concentrations of large whales during certain periods of the year.
Lookouts must use that knowledge to help inform their visual
observations during military readiness activities that involve vessel
movements, active sonar, in-water explosives (including underwater
explosives and explosives deployed against surface targets), or the
deployment of non-explosive ordnance against surface targets in the
mitigation area. These messages would minimize potential large whale
vessel interactions and exposure to acoustic, explosive, and physical
disturbance and strike stressors that have the potential to cause
mortality, injury, or behavioral disturbance during reproductive
seasons, foraging and migration seasons, and to resident whales.
In addition to the nature and context of the disturbance, including
whether take occurs in a known BIA, species-specific factors affect the
severity of impacts to individual animals and population consequences
of disturbance. Keen et al. (2021) identifies three population
consequences of disturbance themes: life history traits, environmental
conditions, and disturbance source characteristics. Life history traits
considered in Keen et al. (2021) include movement ecology (whether
animals are resident, nomadic, or migratory), reproductive strategy
(capital breeders, income breeders, or mixed), body size (based on size
and life stage), and pace of life (slow or fast).
Regarding movement ecology, resident animals that have small home
ranges relative to the size and duration of an impact zone would have a
higher risk of repeated exposures to an ongoing activity. Animals that
are nomadic over a larger range may have less predictable risk of
repeated exposure. For resident and nomadic populations, overlap of a
stressor with feeding or reproduction depends more on time of year
rather than location in their habitat range. In contrast, migratory
animals may have higher or reduced potential for exposure during
feeding and reproduction based on both location, time of the year, and
duration of an activity. The risk of repeated exposure during
individual events may be lower during migration as animals maintain
directed transit through an area.
Reproduction is energetically expensive for female marine mammals,
and reproductive strategy can influence an animal's sensitivity to
disturbance. Mysticetes and phocids are capital breeders. Capital
breeders rely on their capital, or energy stores, to migrate, maintain
pregnancy, and nurse a calf. Capital breeders would be more resilient
to short-term foraging disruption due to their reliance on built-up
energy reserves, but are vulnerable to prolonged foraging impacts
during gestation. Otariids and most odontocetes are income breeders,
which rely on some level of income, or regular foraging, to give birth
and nurse a calf. Income breeders would be more sensitive to the
consequences of disturbances that impact foraging during lactation.
Some species exhibit traits of both, such as beaked whales.
Smaller animals require more food intake per unit body mass than
large animals. They must consume food on a regular basis and are likely
to be non-migratory and income breeders. The smallest odontocetes, the
porpoises, must maintain high metabolisms to maintain thermoregulation
and cannot rely on blubber stores for long periods of time, whereas
larger odontocetes can more easily thermoregulate. The larger size of
other odontocetes is an adaptation for deep diving that allows them to
access high quality mesopelagic and bathypelagic prey. Both small and
large odontocetes have lower foraging efficiency than the large whales.
The filter-feeding large whales (i.e., mysticetes) consume most of
their food within several months of the year and rely on extensive
lipid reserves for the remainder of the year. The metabolism of
mysticetes allows for fasting while seeking prey patches during
foraging season and prolonged periods of fasting outside of foraging
season (Goldbogen et al., 2023). Their energy stores support capital
breeding and long migrations. The effect of a temporary feeding
disturbance is likely to have inconsequential impacts to a mysticete,
but may be consequential for small cetaceans. Despite their relatively
smaller size, amphibious pinnipeds have lower thermoregulatory
requirements because they spend a portion of time on land. For purposes
of this assessment, marine mammals were generally categorized as small
(less than 10 ft (3.05 m)), medium (10-30 ft (3.05-9.1 m)), or large
(more than 30 ft (9.1 m)) based on length.
Populations with a fast pace of life are characterized by early age
of maturity, high birth rates, and short life spans, whereas
populations with a slow pace of life are characterized by later age of
maturity, low birth rates, and long life spans. The consequences of
disturbance in these populations differ. Although reproduction in
populations with a fast pace of life are more sensitive to foraging
disruption, these populations are quick to recover. Reproduction in
populations with a slow pace of life is

[[Page 32298]]

resilient to foraging disruption, but late maturity and low birth rates
mean that long-term impacts to breeding adults have a longer-term
effect on population growth rates. Pace of life was categorized for
each species in this analysis by comparing age at sexual maturity,
birth rate interval, life span, body size, and feeding and reproductive
strategy.
Southall et al. (2023) also identified factors that inform a
population's vulnerability. The authors describe a framework to assess
risk to populations from specific industry impact scenarios at
different locations or times of year. While this approach may not be
suitable for many military readiness activities, for which alternate
spatial or seasonal scenarios are not usually feasible, the concepts
considered in that framework's population vulnerability assessment are
useful in this analysis, including population status (endangered or
threatened), population trend (decreasing, stable, or increasing),
population size, and chronic exposure to other anthropogenic or
environmental stressors (e.g., fisheries interactions, pollution,
etc.). These factors are also considered when assessing the overall
vulnerability of a stock to repeated effects from acoustic and
explosive stressors.
In consideration of the factors outlined above, if impacts to
individuals increase in magnitude or severity such that repeated and
sequential higher severity impacts occur (the probability of this goes
up for an individual the higher total number of takes it has) or the
total number of moderate to more severe impacts increases
substantially, especially if occurring across sequential days, then it
becomes more likely that the aggregate effects could potentially
interfere with feeding enough to reduce energy budgets in a manner that
could impact reproductive success via longer cow-calf intervals,
terminated pregnancies, or calf mortality. It is important to note that
these impacts only accrue to females, which only comprise approximately
50 percent of the population. Based on energetic models, it takes
energetic impacts of a significantly greater magnitude to cause the
death of an adult marine mammal, and females will always terminate a
pregnancy or stop lactating before allowing their health to
deteriorate. Also, the death of an adult female has significantly more
impact on population growth rates than reductions in reproductive
success, while the death of an adult male has very little effect on
population growth rates. However, as previously explained, such severe
impacts from the specified activities would be very infrequent and not
considered likely to occur at all for most species and stocks. We note
that the negligible impact analysis is inherently a two-tiered
assessment that first evaluates the anticipated impacts of the
activities on marine mammals individuals, and then if impacts are
expected to reproduction or survival of any individuals further
evaluates the effects of those individual impacts on rates of
reproduction and survival of the species or stock, in the context of
the status of the species or stock. The analyses below in some cases
address species collectively if they occupy the same functional hearing
group (i.e., very-low, low, high, and very high-frequency cetaceans),
share similar life history strategies, and/or are known to behaviorally
respond similarly to acoustic stressors. Because some of these groups
or species share characteristics that inform the impact analysis
similarly, it would be duplicative to repeat the same analysis for each
species. In addition, similar species typically have the same hearing
capabilities and behaviorally respond in the same manner.
Thus, our analysis below considers the effects of the specified
activities on each affected species or stock even where discussion is
organized by functional hearing group and/or information is evaluated
at the group level. Where there are meaningful differences between a
species or stock that would further differentiate the analysis, they
are either described within the section or the discussion for those
species or stocks is included as a separate part of each section.
Specifically, we first give broad descriptions of the mysticete,
odontocete, and pinniped groups and then differentiate into further
groups as appropriate below.
Mysticetes
This section builds on the broader discussion above and brings
together the discussion of the different types and amounts of take that
different stocks will incur, the applicable mitigation for each stock,
and the status and life history of the stocks to support the negligible
impact determinations for each stock. We have already described above
why we believe the incremental addition of the limited number of low-
level auditory injury takes will not have any meaningful effect towards
inhibiting reproduction or survival. We have also described in this
section above the unlikelihood of any masking or habitat impacts having
effects that would impact the reproduction or survival of any of the
individual marine mammals affected by the Action Proponents'
activities. For mysticetes, there is no predicted non-auditory injury
from explosives for any stocks except the CA/OR/WA stock of fin whale
and the Mainland Mexico-CA/OR/WA stock of humpback whale. Regarding the
severity of individual takes by Level B harassment by behavioral
disturbance for mysticetes, the majority of these responses are
anticipated to occur at received levels below 172 dB, and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Much of the
discussion below focuses on the behavioral effects and the mitigation
measures that reduce the probability or severity of effects in
biologically important areas or other habitat. Because there are
multiple stock-specific factors in relation to the status of the
species, as well as mortality take due to vessel strike for several
stocks, at the end of the section we break out stock-specific findings.
In table 89 below for mysticetes, we indicate the total annual
mortality, Level A harassment, and Level B harassment, and a number
indicating the instances of total take as a percentage of abundance.
In table 90 below, we indicate the status, life history traits,
important habitats, and threats that inform our analysis of the
potential impacts of the estimated take on the affected mysticete
stocks.

[[Page 32299]]

Table 89--Annual Estimated Take by Level B Harassment, Level A Harassment, and Mortality and Related Information for Mysticetes in the HCTT Study Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
annual
Maximum Maximum Maximum Maximum harassment Season(s) with 50 Region(s) with 40
Marine mammal species Stock NMFS stock NMSDD annual annual annual annual as percent of take or percent of take or
abundance abundance Level B Level A mortality take percentage greater greater
harassment harassment of stock
abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale........................ Eastern North Pacific 26,960 10,863 16,711 167 0.43 16,878 63 Cold (99 percent).... SOCAL (98 percent).
Gray Whale........................ Western North Pacific 290 110 169 2 0 171 59 Cold (100 percent)... SOCAL (97 percent).
Blue Whale........................ Central North Pacific 133 170 92 1 0 93 55 Cold (70 percent).... HRC (95 percent).
Blue Whale........................ Eastern North Pacific 1,898 3,233 4,571 27 0.29 4,598 142 Warm (56 percent).... SOCAL (87 percent).
Bryde's Whale..................... Eastern Tropical UNK 69 322 5 0 327 474 Cold (56 percent).... SOCAL (89 percent).
Pacific.
Bryde's Whale..................... Hawaii............... 791 766 409 3 0 412 52 Cold (57 percent).... HRC (93 percent).
Fin Whale......................... Hawaii............... 203 226 86 1 0 87 38 Cold (75 percent).... HRC (97 percent).
Fin Whale......................... California/Oregon/ 11,065 12,304 13,501 55 0.57 13,557 110 Warm (70 percent).... SOCAL (52 percent).
Washington.
Humpback Whale.................... Central America/ 1,496 1,603 1,888 19 0.29 1,907 119 Cold (71 percent).... SOCAL (56 percent).
Southern Mexico--
California-Oregon-
Washington.
Humpback Whale.................... Mainland Mexico-- 3,477 3,741 4,449 44 0.29 4,493 120 Cold (71 percent).... SOCAL (58 percent).
California-Oregon-
Washington.
Humpback Whale.................... Hawaii............... 11,278 9,806 3,034 24 0.43 3,058 27 Cold (99 percent).... HRC (98 percent).
Minke Whale....................... Hawaii............... 438 509 296 3 0 299 59 Cold (70 percent).... HRC (96 percent).
Minke Whale....................... California/Oregon/ 915 1,342 2,993 32 0 3,025 225 N/A.................. SOCAL (75 percent).
Washington.
Sei Whale......................... Hawaii............... 391 452 253 2 0 255 56 Cold (69 percent).... HRC (95 percent).
Sei Whale......................... Eastern North Pacific 864 155 302 3 0.29 305 35 Cold (58 percent).... SOCAL (72 percent).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UNK = Unknown. NMSDD abundances are averages only within the U.S. EEZ.
* Indicates which abundance estimate was used to calculate the maximum annual take as a percentage of abundance, either the NMFS SARs (Carretta et al., 2024; Young, 2024) or the NMSDD (table
2.4-1 in appendix A of the application). Please refer to the Mysticetes section for details on which abundance estimate was selected.

[[Page 32300]]

Table 90--Life History Traits, Important Habitat, and Threats to Dolphins in the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annual
BIAs II for mortality/
ESA- designated Hawaii (Kratofil serious
Marine mammal species Stock ESA status MMPA status Movement ecology Body size Reproductive Pace of life Chronic risk UME, oil critical et al., 2023) and Population trend PBR injury
strategy factors spill, other habitat West Coast (from other
(Calambokidis et human
al., 2024) activities)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gray Whale..................... Eastern North Not listed....... Not depleted, not Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. Yes: F-BIA Parent Increasing....... 801 131
Pacific. strategic. fisheries and Core; M-BIA
interactions, Parent and
habitat Child; R-BIA.
degradation,
pollution, vessel
disturbance,
ocean noise,
subsistence
hunting.
Gray Whale..................... Western North Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 0.12 UNK
Pacific. Strategic. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise,
subsistence
hunting.
Blue Whale..................... Central North Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 0.1 0
Pacific. Strategic. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Blue Whale..................... Eastern North Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. Yes: F-BIA Parent Unk, possibly 4.1 >=18.6
Pacific. Strategic. fisheries and Core. increasing.
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.

[[Page 32301]]

Bryde's Whale.................. Eastern Tropical Not listed....... Not depleted, not Unknown, likely Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. UND UNK
Pacific. strategic. migratory. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Bryde's Whale.................. Hawaii............ Not listed....... Not depleted, not Unknown, likely Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 6.2 0
strategic. migratory. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Fin Whale...................... Hawaii............ Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 0.2 0
Strategic. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Fin Whale...................... California/Oregon/ Endangered....... Depleted, Migratory-........ Large........ Capital............ Slow......... Vessel strikes, No........... No............. Yes: F-BIA Parent Unk.............. 80 >=43.4
Washington. Strategic. resident (SOCAL).. fisheries and Core.
interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Humpback Whale................. Central America/ Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... Yes............ Yes: F-BIA Parent Increasing....... 3.5 14.9
Southern Mexico-- Strategic. fisheries and Core.
California-Oregon- interactions,
Washington. habitat
degradation,
pollution, vessel
disturbance,
ocean noise.

[[Page 32302]]

Humpback Whale................. Mainland Mexico-- Threatened....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... Yes............ Yes: F-BIA Parent Unk.............. 43 22
California-Oregon- Strategic. fisheries and Core.
Washington. interactions,
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Humpback Whale................. Hawaii............ Not listed....... Not depleted, not Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. Yes: R-BIA MHI Unk.............. 127 27.09
strategic. fisheries and MHI-Core
interactions, Parent and Child.
habitat
degradation,
pollution, vessel
disturbance,
ocean noise.
Minke Whale.................... Hawaii............ Not listed....... Not depleted, not Migratory......... Med-Large.... Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 2.1 0
strategic. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance.
Minke Whale.................... California/Oregon/ Not listed....... Not depleted, not Migratory-resident Med-Large.... Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 4.1 >=0.19
Washington. strategic. fisheries
interactions,
habitat
degradation,
pollution, vessel
disturbance.
Sei Whale...................... Hawaii............ Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 0.4 0.2
Strategic. fisheries
interactions,
ocean noise.

[[Page 32303]]

Sei Whale...................... Eastern North Endangered....... Depleted, Migratory......... Large........ Capital............ Slow......... Vessel strikes, No........... No............. No............... Unk.............. 1.25 UNK
Pacific. Strategic. fisheries
interactions,
ocean noise.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UND = Undetermined, Unk = Unknown.

[[Page 32304]]

Gray Whale (Eastern North Pacific and Western North Pacific Stocks)--
Gray whales from the Eastern North Pacific stock are not listed
under the ESA and are not considered as depleted or strategic under the
MMPA, while gray whales from the Western North Pacific stock are listed
as endangered under the ESA and depleted and strategic under the MMPA.
Both stocks are migratory and most likely to be in the California Study
Area during their migrations from winter to spring within 10 km (5.4
nmi) of the coast. Some gray whales transit further offshore in
Southern California when making straight line transits south of Point
Conception to and from Mexico. Gray whales face several chronic
anthropogenic and non-anthropogenic risk factors, including vessel
strikes, fisheries interactions, habitat degradation, pollution, vessel
disturbance, ocean noise, and subsistence hunting, among others.
The current stock abundance estimate of the Eastern North Pacific
stock of gray whale is 26,960 animals and for the Western North Pacific
stock is 290 animals. There are no UMEs or other factors that cause
particular concern for these stocks. As described in the Description of
Marine Mammals and Their Habitat in the Area of the Specified
Activities section, the HCTT Study Area overlaps eight BIAs for the
Eastern North Pacific stock, including three feeding, four migratory,
and one reproductive for the nearshore migratory corridor used by cow/
calf pairs. As shown in table 89, the maximum annual allowable
instances of take under this proposed rule by Level A harassment and
Level B harassment are 167 and 16,711, respectively. As indicated, the
rule also allows for up to three takes by serious injury or mortality
over the course of the 7-year rule, the impacts of which are discussed
above in the Serious Injury and Mortality section.
There are no known biologically important areas for the Western
North Pacific stock of gray whale in the HCTT Study Area, though the
Western North Pacific stock may use the same migratory areas as the
Eastern North Pacific stock while migrating to wintering areas in
Mexico (Calambokidis et al., 2024). As shown in table 89, the maximum
annual allowable instances of take under this proposed rule by Level A
harassment and Level B harassment are 2 and 169, respectively. No
mortality is anticipated or proposed for authorization, nor is any non-
auditory injury. The total take allowable across all 7 years of the
rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with gray whale communication or other important low-frequency cues.
Any associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Gray whales are
large-bodied capital breeders with a slow pace of life and are
therefore generally less susceptible to impacts from shorter duration
foraging disruptions. Further, as described in the Group and Species-
Specific Analyses section above and the Proposed Mitigation Measures
section, mitigation measures are expected to further reduce the
potential severity of impacts through real-time operational measures
that minimize higher level/longer duration exposures and time/area
measures that reduce impacts in high value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of take, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, given the
number of takes by harassment as compared to the stock/species
abundance (see table 89), and the fact that a portion of the takes of
the Eastern North Pacific occur in BIAs, it is likely that some portion
of the individuals taken are taken repeatedly over a limited number of
days. However, given the variety of activity types that contribute to
take across separate exercises conducted at different times and in
different areas, and the fact that many result from transient
activities conducted at sea, it is unlikely that repeated takes would
occur either in numbers across sequential days in a manner likely to
impact foraging success and energetics or other behaviors such that
reproduction or survival of any individuals is likely to be impacted.
Given the magnitude and severity of the impacts discussed above to
the Western North Pacific stock (considering annual take maxima and the
total across 7 years) and their habitat, and in consideration of the
required mitigation measures and other information presented, the
Action Proponents' activities are unlikely to result in impacts on the
reproduction or survival of any individuals and, thereby, unlikely to
affect annual rates of recruitment or survival. For the Eastern North
Pacific stock, as analyzed and described in the Serious Injury and
Mortality section, given the status of the stock and in consideration
of other ongoing anthropogenic mortality (fisheries interactions,
vessel strike), the M/SI proposed for authorization (three over the
course of the 7-year rule, or 0.43 annually) would not, alone, nor in
combination with the impacts of the take by harassment discussed above
(which is not expected to impact the reproduction or survival of any
individuals), be expected to adversely affect rates of recruitment and
survival for any of this stock. For these reasons, we have determined
that the total take (considering annual maxima and across 7 years)
anticipated and proposed for authorization would have a negligible
impact on the Eastern North Pacific and Western North Pacific stocks of
gray whale.
Blue Whale (Central North Pacific and Eastern North Pacific Stocks)--
Blue whales are listed as endangered under the ESA and as both
depleted and strategic under the MMPA. Both stocks of blue whales are
migratory populations that can occur near the coast, over the
continental shelf, and in oceanic waters. Blue whales face several
chronic anthropogenic and non-anthropogenic risk factors, including
vessel strike, fisheries interactions, habitat degradation, pollution,
vessel disturbance, and ocean noise, among others.
The Navy's NMSDD estimates the Central North Pacific stock
abundance as 170, and the Eastern North Pacific stock abundance as
3,233. The Central North Pacific stock's primary range is outside of
the HCTT Study Area. There are no UMEs or other factors that cause

[[Page 32305]]

particular concern for this stock, and there are no known biologically
important areas for the Central North Pacific stock of blue whales in
the HCTT Study Area. This stock migrates from their feeding grounds in
the Gulf of Alaska to Hawaii in winter. While they occur in the Hawaii
Study Area, they are not sighted frequently or year-round. As shown in
table 89, the maximum annual allowable instances of take under this
proposed rule by Level A harassment and Level B harassment is 1 and 92,
respectively. No mortality is anticipated or proposed for
authorization, nor is any non-auditory injury. The total take allowable
across all 7 years of the rule is indicated in table 54.
For the Eastern North Pacific stock, there are no UMEs or other
factors that cause additional concern for this stock. As described in
the Description of Marine Mammals and Their Habitat in the Area of the
Specified Activities section, the HCTT Study Area overlaps a feeding
BIA for the Eastern North Pacific stock (Calambokidis et al., 2024).
The Eastern North Pacific stock of blue whales is a migratory
population that can occur near the coast, over the continental shelf,
and in deep oceanic waters from the northern Gulf of Alaska to the
eastern tropical Pacific. This stock forages in their hierarchical
feeding BIAs off California in warmer months (June-November). In recent
years, the Eastern North Pacific stock has been reported to spend more
time (averaging over 8 months) on feeding grounds in the Southern
California Bight. The highest densities of blue whales are predicted
along nearshore southern California where most impacts would occur, so
blue whales may be impacted while foraging in the designated BIAs. As
shown in table 89, the maximum annual allowable instances of take under
this proposed rule by Level A Harassment and Level B harassment is 27
and 4,571, respectively. As indicated, the rule also allows for up to
two takes by serious injury or mortality over the course of the 7-year
rule, the impacts of which are discussed above in the Serious Injury
and Mortality section. The total take allowable across all 7 years of
the rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with blue whale communication or other important low-frequency cues.
Any associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Blue whales are
large-bodied capital breeders with a slow pace of life, and are
therefore generally less susceptible to impacts from shorter duration
foraging disruptions. Further, as described in the Group and Species-
Specific Analyses section above and the Proposed Mitigation Measures
section, mitigation measures are expected to further reduce the
potential severity of impacts through real-time operational measures
that minimize higher level/longer duration exposures and time/area
measures that reduce impacts in high value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, for the
Central North Pacific stock, given the lower number of takes by
harassment as compared to the stock/species abundance (see table 89),
their migratory movement pattern, and the absence of take concentrated
in areas in which animals are known to congregate, it is unlikely that
any individual blue whales from the Central North Pacific stock would
be taken on more than a limited number of days within a year and,
therefore, the anticipated behavioral disturbance is not expected to
affect reproduction or survival. For the Eastern North Pacific stock,
given the number of takes by harassment as compared to the stock/
species abundance (see table 89) and the fact that a portion of the
takes occur in BIAs, it is likely that some portion of the individuals
taken are taken repeatedly over a limited number of days. However,
given the variety of activity types that contribute to take across
separate exercises conducted at different times and in different areas
(i.e., not concentrated within a specific region and season), and the
fact that many result from transient activities conducted at sea, it is
unlikely that repeated takes would occur either in numbers or clumped
across sequential days in a manner likely to impact foraging success
and energetics or other behaviors such that reproduction or survival of
any individuals is likely to be impacted.
Given the magnitude and severity of the impacts discussed above to
the Central North Pacific stock of blue whales (considering annual take
maxima and the total across 7 years) and their habitat, and in
consideration of the required mitigation measures and other information
presented, the Action Proponents' activities are not expected to result
in impacts on the reproduction or survival of any individuals, much
less affect annual rates of recruitment or survival. For the Eastern
North Pacific stock, as analyzed and described in the Serious Injury
and Mortality section, given the status of the stock, and in
consideration of other ongoing anthropogenic mortality (fisheries
interactions, vessel strike), the M/SI proposed for authorization (two
over the course of the 7-year rule, or 0.29 annually) would not, alone,
nor in combination with the impacts of the take by harassment discussed
above (which is not expected to impact the reproduction or survival of
any individuals), be expected to adversely affect rates of recruitment
and survival for any of this stock. For these reasons, we have
determined that the total take (considering annual maxima and across 7
years) anticipated and proposed for authorization would have a
negligible impact on the Eastern North Pacific and Central North
Pacific stocks of blue whale.
Bryde's Whale (Eastern Tropical Pacific and Hawaii Stocks)--
Little is known about the movements of Bryde's whales in the Study
Area, but seasonal shifts in their distribution occur toward and away
from the equator in winter and summer. Therefore, both populations of
Bryde's whales are at least somewhat migratory populations that travel
within their tropical and subtropical ranges year-round. There are no
known biologically important areas for Bryde's whales in the HCTT Study
Area. Bryde's whales face several chronic anthropogenic and non-
anthropogenic risk factors, including vessel strike, fisheries
interactions,

[[Page 32306]]

habitat degradation, pollution, vessel disturbance, and ocean noise,
among others.
Bryde's whales in the Eastern Tropical Pacific have not been
designated as a stock under the MMPA, are not ESA-listed, and there is
no current reported population trend. The Navy's NMSDD estimates the
Eastern Tropical Pacific Bryde's whale is 69 animals. As shown in table
89, the maximum annual allowable instances of take under this proposed
rule by Level A harassment and Level B harassment is 5 and 322,
respectively. No mortality is anticipated or proposed for
authorization, nor is any non-auditory injury. The total take allowable
across all 7 years of the rule is indicated in table 54.
The Hawaii stock of Bryde's whale is not listed as threatened or
endangered under the ESA and is not considered depleted or strategic
under the MMPA. The current stock abundance estimate of the Hawaii
stock of Bryde's whale is 791 animals. The stock's primary range
extends outside of the HCTT Study Area. There are no UMEs or other
factors that cause particular concern for this stock. Bryde's whales
are the only baleen whale found in Hawaiian waters year-round, and the
only mysticete in Hawaii that does not undergo predictable north-south
seasonal migrations. However, Bryde's whales occur mostly in offshore
waters of the North Pacific. As shown in table 89, the maximum annual
allowable instances of take under this proposed rule by Level A
harassment and Level B harassment is 3 and 409, respectively. No
mortality is anticipated or proposed for authorization, nor is any non-
auditory injury. The total take allowable across all 7 years of the
rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with Bryde's whale communication or other important low-frequency cues.
Any associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Bryde's whales
are large-bodied capital breeders with a slow pace of life, and are
therefore generally less susceptible to impacts from shorter duration
foraging disruptions. Further, as described in the Group and Species-
Specific Analyses section above and the Proposed Mitigation Measures
section, mitigation measures are expected to further reduce the
potential severity of impacts to the Hawaii stock through real-time
operational measures that minimize higher level/longer duration
exposures and time/area measures that reduce impacts in high value
habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, given the
number of takes by harassment as compared to the stock/species
abundance (see table 89), it is likely that some portion of the
individuals taken from the Eastern Tropical Pacific stock are taken
repeatedly over a moderate number of days. However, given the variety
of activity types that contribute to take across separate exercises
conducted at different times and in different areas, and the fact that
many result from transient activities conducted at sea, it is unlikely
that repeated takes would occur either in numbers or clumped across
sequential days in a manner likely to impact foraging success and
energetics or other behaviors such that reproduction or survival of any
individuals is likely to be impacted. For the Hawaii stock, given the
lower number of takes by harassment as compared to the stock/species
abundance (see table 89), their migratory movement pattern, and the
absence of take concentrated in areas in which animals are known to
congregate, it is unlikely that any individual Bryde's whales from the
Hawaii stock would be taken on more than a limited number of days
within a year and, therefore, the anticipated behavioral disturbance is
not expected to affect reproduction or survival.
Given the magnitude and severity of the impacts discussed above to
Bryde's whales in the Eastern Tropical Pacific (considering annual take
maxima and the total across 7 years) and their habitat, and in
consideration of the required mitigation measures and other information
presented, the Action Proponents' activities are not expected to result
in impacts on the reproduction or survival of any individuals, much
less affect annual rates of recruitment or survival. For these reasons,
we have determined that the take anticipated and proposed for
authorization would have a negligible impact on the Eastern Tropical
Pacific and Hawaii stocks of Bryde's whale.
Fin Whale (Hawaii and CA/OR/WA Stocks)--
Fin whales are listed as endangered under the ESA and depleted and
strategic under the MMPA. Fin whales have higher abundances in
temperate and polar waters, and are not frequently seen in warm,
tropical waters. Fin whales face several chronic anthropogenic and non-
anthropogenic risk factors, including vessel strike, fisheries
interactions, habitat degradation, pollution, vessel disturbance, and
ocean noise, among others.
The Navy's NMSDD estimates the abundance of the Hawaii stock of fin
whale is 226 and the CA/OR/WA stock of fin whale is 12,304. There are
no UMEs or other factors that cause particular concern for these
stocks, and there are no known biologically important areas for the
Hawaii stock of fin whale in the HCTT Study Area. The Hawaii stock of
fin whales are not sighted frequently or year-round, and likely only
migrate to the Hawaii portion of the HCTT Study Area during fall and
winter. As shown in table 89, the maximum annual allowable instances of
take under this proposed rule by Level A Harassment and Level B
harassment is 1 and 86, respectively. No mortality is anticipated or
proposed for authorization, nor is any non-auditory injury. The total
take allowable across all 7 years of the rule is indicated in table 54.
For the CA/OR/WA stock, as described in the Description of Marine
Mammals and Their Habitat in the Area of the Specified Activities
section, the HCTT Study Area overlaps a feeding BIA (Parent and Child)
for this stock (Calambokidis et al., 2024). This stock of fin whales is
a migratory-resident population that travels along the entire U.S. west
coast and may be present

[[Page 32307]]

throughout the year in southern and central California. There are
generally higher densities farther offshore in the summer and fall, and
closer to shore in winter and spring. As shown in table 89, the maximum
annual allowable instances of take under this proposed rule by Level A
Harassment and Level B harassment is 55 and 13,501, respectively. The
rule allows for a limited number of takes by non-auditory injury (1
animal). As indicated, the rule also allows for up to four takes by
serious injury or mortality over the course of the 7-year rule, the
impacts of which are discussed above in the Serious Injury and
Mortality section. The total take allowable across all 7 years of the
rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with fin whale communication and other important low-frequency cues.
Any associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness. The rule also allows for a limited number of takes by non-
auditory injury (i.e., 1 animal) for this stock. As described above in
the Auditory Injury from Sonar Acoustic Sources and Explosives and Non-
Auditory Injury from Explosives section, given the limited number of
potential exposures and the anticipated effectiveness of the mitigation
measures in minimizing the pressure levels to which any individuals are
exposed, these non-auditory injuries are unlikely to be of a nature or
level that would impact reproduction or survival.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Fin whales are
large-bodied capital breeders with a slow pace of life and are
therefore generally less susceptible to impacts from shorter duration
foraging disruptions. Further, as described in the Group and Species-
Specific Analyses section above and the Proposed Mitigation Measures
section, mitigation measures are expected to further reduce the
potential severity of impacts through real-time operational measures
that minimize higher level/longer duration exposures and time/area
measures that reduce impacts in high value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, given the
number of takes by harassment as compared to the stock/species
abundance (see table 89) and the fact that a portion of the takes occur
in BIAs for the CA/OR/WA stock, it is likely that some portion of the
individuals of each stock are taken repeatedly over a limited number of
days. However, given the variety of activity types that contribute to
take across separate exercises conducted at different times and in
different areas, and the fact that many result from transient
activities conducted at sea, it is unlikely that repeated takes would
occur either in numbers or clumped across sequential days in a manner
likely to impact foraging success and energetics or other behaviors
such that reproduction or survival of any individuals is likely to be
impacted.
Fin whales have the largest hierarchal feeding BIAs spanning the
coast of California from June to November, which overlap more with PMSR
and SOCAL compared to NOCAL, as the core BIAs are generally farther
offshore in northern California. Impacts would be attributable to
various activities in summer and fall (warm season), with most impacts
occurring in southern California year-round. However, this stock is
migratory and Navy activities are not anticipated to overlap a large
portion of the BIAs, leaving large areas of important foraging habitat
available.
Given the magnitude and severity of the impacts discussed above to
the Hawaii stock of fin whales (considering annual take maxima and the
total across 7 years) and their habitat, and in consideration of the
required mitigation measures and other information presented, the
Action Proponents' activities are unlikely to result in impacts on the
reproduction or survival of any individuals and, thereby, unlikely to
affect annual rates of recruitment or survival. For the CA/OR/WA stock,
as analyzed and described in the Serious Injury and Mortality section,
given the status of the stock and in consideration of other ongoing
anthropogenic mortality (fisheries interactions, vessel strike), the M/
SI proposed for authorization (three over the course of the 7-year
rule, or 0.57 annually) would not, alone, nor in combination with the
impacts of the take by harassment discussed above (which is not
expected to impact the reproduction or survival of any individuals), be
expected to adversely affect rates of recruitment and survival for any
of this stock. For these reasons, we have determined that the total
take (considering annual maxima and across 7 years) anticipated and
proposed for authorization would have a negligible impact on the CA/OR/
WA and Hawaii stocks of fin whale.
Humpback Whale (Central America/Southern Mexico--CA/OR/WA, Mainland
Mexico--CA/OR/WA, and Hawaii Stocks)--
Humpback whales occur throughout the HCTT Study Area, and the two
stocks (Central America/Southern Mexico--CA/OR/WA and Mainland Mexico--
CA/OR/WA) found in the California portion of the Study Area most
abundant in shelf and slope waters which are areas of high productivity
and often sighted near shore, while also frequently moving through deep
offshore waters during migration. In the Hawaii portion of the Study
Area, the Hawaii of humpback whales occur seasonally in nearshore
waters surrounding the main Hawaiian Islands during breeding season
(typically December through May). The HCTT Study Area overlaps ESA-
designated critical habitat for the endangered Central America DPS and
the Mexico DPS of humpback whales along the west coast (86 FR 21082,
April 21, 2021), as described in the Description of Marine Mammals in
the Area of Specified Activities section. There are no UMEs or other
factors that cause particular concern for these stocks. The HCTT Study
Area overlaps a feeding BIA (Parent and Core) for the two stocks found
in California (Calambokidis et al., 2024), and a reproductive BIA
(Parent and Child) for the Hawaii stock (Kratofil et al., 2023).
Humpback whales face several anthropogenic and non-anthropogenic risk
factors, including vessel strikes, fisheries interactions, habitat
degradation, pollution, vessel disturbance, and ocean noise, among
others.

[[Page 32308]]

The Central America/Southern Mexico--CA/OR/WA stock (Central
America DPS) of humpback whale is listed as endangered under the ESA
and as both depleted and strategic under the MMPA. The Navy's NMSDD
estimates this stock size is 1,603. As shown in table 89, the maximum
annual allowable instances of take under this proposed rule by Level A
harassment and Level B harassment is 19 and 1,888, respectively. As
indicated, the rule also allows for up to two takes by serious injury
or mortality over the course of the 7-year rule, the impacts of which
are discussed above in the Serious Injury and Mortality section.
The Mainland Mexico--CA/OR/WA stock (part of the Mexico DPS) of
humpback whale is listed as threatened under the ESA and as both
depleted and strategic under the MMPA. The Navy's NMSDD estimates this
stock size is 3,741. As shown in table 89, the maximum annual allowable
instances of take under this proposed rule by Level A harassment and
Level B harassment is 44 and 4,449 respectively. The rule allows for a
limited number of takes by non-auditory injury (i.e., 1 animal). As
described above, given the limited number of potential exposures and
the anticipated effectiveness of the mitigation measures in minimizing
the pressure levels to which any individuals are exposed, these
injuries are unlikely to impact reproduction or survival. As indicated,
the rule also allows for up to two takes by serious injury or mortality
over the course of the 7-year rule, the impacts of which are discussed
above in the Serious Injury and Mortality section.
The Hawaii stock of humpback whale is not listed as endangered
under the ESA and as neither depleted nor strategic under the MMPA. The
current stock abundance estimate of the Hawaii stock (Hawaii DPS) is
11,278. The stock's primary range extends outside of the HCTT Study
Area. As shown in table 89, the maximum annual allowable instances of
take under this proposed rule by Level A harassment and Level B
harassment is 24 and 3,034, respectively. As indicated, the rule also
allows for up to three takes by serious injury or mortality over the
course of the 7-year rule, the impacts of which are discussed above in
the Serious Injury and Mortality section. The total take allowable for
each stock across all 7 years of the rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with humpback whale communication or other important low-frequency
cues. Any associated lost opportunities or capabilities individuals
might experience as a result of TTS would not be at a level or duration
that would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness. The rule also allows for one take by non-auditory injury for
the Mainland Mexico-CA/OR/WA stock. As described above, given the
limited number of potential exposures and the anticipated effectiveness
of the mitigation measures in minimizing the pressure levels to which
any individuals are exposed, this non-auditory injury is unlikely to be
of a nature or level that would impact reproduction or survival.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Humpback whales
are large-bodied capital breeders with a slow pace of life and are
therefore generally less susceptible to impacts from shorter duration
foraging disruptions. Further, as described in the Group and Species-
Specific Analyses section above and the Proposed Mitigation Measures
section, mitigation measures are expected to further reduce the
potential severity of impacts through real-time operational measures
that minimize higher level/longer duration exposures and time/area
measures that reduce impacts in high value habitat. In particular, for
the Mainland Mexico-CA/OR/WA stock, this proposed rulemaking includes
the Northern California Large Whale Mitigation Area and Central
California Large Whale Mitigation Area. Within this area from June 1-
October 31, the Action Proponents must not use more than 300 hours of
MF1 surface ship hull-mounted mid-frequency active sonar (excluding
normal maintenance and systems checks) total during training and
testing within the combination of this mitigation area, the Central
California Large Whale Mitigation Area, and the Southern California
Blue Whale Mitigation Area. These restrictions would reduce exposure of
humpback whales in important seasonal foraging, migratory, and calving
habitats to levels of sound that have the potential to cause injurious
or behavioral impacts.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, for the
Mainland Mexico-CA/OR/WA and Central America/Southern Mexico-CA/OR/WA
stocks, given the number of takes by harassment as compared to the
stock/species abundance (see table 89) and the fact that a portion of
the takes of both stocks occur in BIAs, it is likely that some portion
of the individuals taken are taken repeatedly over a limited number of
days. However, given the variety of activity types that contribute to
take across separate exercises conducted at different times and in
different areas, and the fact that many result from transient
activities conducted at sea, it is unlikely that repeated takes would
occur either in numbers or clumped across sequential days in a manner
likely to impact foraging success and energetics or other behaviors
such that reproduction or survival of any individuals is likely to be
impacted. Further, these stocks are migratory, and although some
impacts to these stocks would occur in critical habitat and BIAs
important for foraging off the coast of California, there are large
areas available outside of the Study Area that contain high-quality
foraging habitat for both stocks. Further, the majority of impacts to
these stocks are anticipated to occur during the cold season, a portion
of which (December to February) the BIAs for feeding are not considered
to be active.
For the Hawaii stock, given the lower number of takes by harassment
as compared to the stock/species abundance (see table 89), their
migratory movement pattern, and the absence of take concentrated in
areas in which animals are known to congregate, it is unlikely that any
individual humpback whales from the Hawaii stock would be taken on more
than a limited number of days within a year and, therefore, the
anticipated behavioral disturbance is not expected to affect
reproduction or survival.
For all three stocks, as described in the Serious Injury and
Mortality section, given the status of the stocks, and in consideration
of other ongoing

[[Page 32309]]

anthropogenic mortality, the amount of allowed M/SI take proposed here
would not, alone, nor in combination with the impacts of the take by
harassment discussed above (which is not expected to impact the
reproduction or survival of any individuals), be expected to adversely
affect rates of recruitment and survival. For these reasons, we have
determined that the total take (considering annual maxima and across 7
years) anticipated and proposed for authorization would have a
negligible impact on the Central America/Southern Mexico-CA/OR/WA,
Mainland Mexico-CA/OR/WA, and Hawaii stocks of humpback whales.
Minke Whale (Hawaii and CA/OR/WA Stocks)--
Minke whales in the HCTT Study Area are not listed as threatened or
endangered under the ESA, and neither the Hawaii stock nor the CA/OR/WA
stock are considered depleted or strategic under the MMPA. There are no
UMEs or other factors that cause particular concern for either stock
and there are no known biologically important areas for minke whales in
the HCTT Study Area. Minke whales face several chronic anthropogenic
and non-anthropogenic risk factors, including vessel strike, fisheries
interactions, habitat degradation, pollution, vessel disturbance, and
disease, among others.
The Navy's NMSDD estimates the abundance of the Hawaii stock of
minke whale is 509 animals and the CA/OR/WA stock of minke whale is
1,342 animals. The stock's primary range extends outside of the HCTT
Study Area. The Hawaii stock generally congregates in Hawaiian water in
the colder months (fall to spring) and migrates to more productive
areas in winter. As shown in table 89, the maximum annual allowable
instances of take under this proposed rule by Level A harassment and
Level B harassment is 3 and 296, respectively. The CA/OR/WA stock can
be found year-round in southern California, generally congregating in
nearshore waters over the continental shelf off California, and has low
variability in annual distribution patterns. As shown in table 89, the
maximum annual allowable instances of take under this proposed rule by
Level A harassment and Level B harassment is 32 and 2,993,
respectively. No mortality is anticipated or proposed for authorization
for either stock, nor is any non-auditory injury. The total take
allowable across all 7 years of the rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration, and mostly not in a frequency band that would be expected to
interfere with minke whale communication or other important low-
frequency cues. Any associated lost opportunities or capabilities
individuals might experience as a result of TTS would not be at a level
or duration that would be expected to impact reproductive success or
survival. For similar reasons, while auditory injury impacts last
longer, the low anticipated levels of AUD INJ that could be reasonably
expected to result from these activities are unlikely to have any
effect on fitness.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Minke whales
are medium-to-large-bodied capital breeders with a slow pace of life
and are therefore generally less susceptible to impacts from shorter
duration foraging disruptions. Further, as described in the Group and
Species-Specific Analyses section above and the Proposed Mitigation
Measures section, mitigation measures are expected to further reduce
the potential severity of impacts through real-time operational
measures that minimize higher level/longer duration exposures and time/
area measures that reduce impacts in high value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, for the
Hawaii stock, given the lower number of takes by harassment as compared
to the stock/species abundance (see table 89), their migratory movement
pattern, and the absence of take concentrated in areas in which animals
are known to congregate, it is unlikely that any individual minke
whales from the Hawaii stock would be taken on more than a limited
number of days within a year and, therefore, the anticipated behavioral
disturbance is not expected to affect reproduction or survival. For the
CA/OR/WA stock, given the number of takes by harassment as compared to
the stock/species abundance (see table 89), it is likely that some
portion of the individuals taken are taken repeatedly over a limited to
moderate number of days. However, given the variety of activity types
that contribute to take across separate exercises conducted at
different times and in different areas, and the fact that many result
from transient activities conducted at sea, it is unlikely that
repeated takes would occur either in numbers or clumped across
sequential days in a manner likely to impact foraging success and
energetics or other behaviors such that reproduction or survival of any
individuals is likely to be impacted.
Given the magnitude and severity of the impacts discussed above to
the CA/OR/WA and Hawaii stocks of minke whale (considering annual take
maxima and the total across 7 years) and their habitat, and in
consideration of the required mitigation measures and other information
presented, the Action Proponents' activities are not expected to result
in impacts on the reproduction or survival of any individuals, much
less affect annual rates of recruitment or survival. For these reasons,
we have determined that the take by harassment anticipated and proposed
for authorization would have a negligible impact on the Hawaii and CA/
OR/WA stocks of minke whales.
Sei Whale (Hawaii and Eastern North Pacific Stocks)--
Sei whales are listed as endangered under the ESA and as both
depleted and strategic under the MMPA. Sei whales generally have higher
abundances in the cold and deep water of the open ocean. There are no
UMEs or other factors that cause particular concern for either stock,
and there are no known biologically important areas for sei whales in
the HCTT Study Area. Sei whales face several chronic anthropogenic and
non-anthropogenic risk factors, including vessel strike, fisheries
interactions, and ocean noise, among others.
The Navy's NMSDD estimates the abundance of the Hawaii stock is 452
and the Eastern North Pacific stock is 864 animals. The Hawaii stock's
primary range is outside of the HCTT Study Area. This stock is
migratory and not frequently detected in Hawaii, traveling from their
cold subpolar latitudes to Hawaii in the winter, where they are more
likely to be on the Hawaii Range Complex in the cold season. As shown
in table 89, the maximum annual allowable instances of take under this
proposed rule by Level A harassment and Level B harassment is 2 and
253, respectively. No mortality of the Hawaii

[[Page 32310]]

stock is anticipated or proposed for authorization, nor is any non-
auditory injury.
The Eastern North Pacific stock occurs year-round in deep offshore
waters of California and is likely to occur in the Transit Corridor of
the HCTT Study Area. The Eastern North Pacific stock seasonally
migrates, though to a lesser extent compared to other large whales. As
shown in table 89, the maximum annual allowable instances of take under
this proposed rule by Level A harassment and Level B harassment is 3
and 302, respectively. As indicated, the rule also allows for up to two
takes by serious injury or mortality over the course of the 7-year
rule, the impacts of which are discussed above in the Serious Injury
and Mortality section. The total take allowable across all 7 years of
the rule for both stocks is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with sei whale communication or other important low-frequency cues. Any
associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Sei whales are
large-bodied capital breeders with a slow pace of life and are
therefore generally less susceptible to impacts from shorter duration
foraging disruptions. Further, as described in the Group and Species-
Specific Analyses section above and the Proposed Mitigation Measures
section, mitigation measures are expected to further reduce the
potential severity of impacts through real-time operational measures
that minimize higher level/longer duration exposures and time/area
measures that reduce impacts in high value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, given the
lower number of takes by harassment as compared to the stock/species
abundance (see table 89), their migratory movement pattern, and the
absence of take concentrated in areas in which animals are known to
congregate, it is unlikely that any individual from either stock would
be taken on more than a limited number of days within a year and,
therefore, the anticipated behavioral disturbance is not expected to
affect reproduction or survival.
Given the magnitude and severity of the impacts discussed above to
the Hawaii stock of sei whales (considering annual take maxima and the
total across 7 years) and their habitat, and in consideration of the
required mitigation measures and other information presented, the
Action Proponents' activities are not expected to result in impacts on
the reproduction or survival of any individuals, much less affect
annual rates of recruitment or survival. For the CA/OR/WA stock, as
analyzed and described in the Serious Injury and Mortality section
above, given the status of the stock, the M/SI proposed for
authorization for CA/OR/WA sei whales (two over the course of the 7-
year rule, or 0.29 annually) would not, alone, be expected to adversely
affect the stock through rates of recruitment or survival. Given the
magnitude and severity of the take by harassment discussed above and
any anticipated habitat impacts, and in consideration of the required
mitigation measures and other information presented, the take by
harassment proposed for authorization is unlikely to result in impacts
on the reproduction or survival of any individuals and, thereby,
unlikely to affect annual rates of recruitment or survival either alone
or in combination with the M/SI proposed for authorization. For these
reasons, we have determined that the take by harassment anticipated and
proposed for authorization would have a negligible impact on the Hawaii
and CA/OR/WA stocks of sei whales.
Odontocetes
This section builds on the broader discussion above and brings
together the discussion of the different types and amounts of take that
different stocks will incur, the applicable mitigation for each stock,
and the status and life history of the stocks to support the negligible
impact determinations for each stock. We have already described above
why we believe the incremental addition of the limited number of low-
level auditory injury takes will not have any meaningful effect towards
inhibiting reproduction or survival. We have also described above in
this section the unlikelihood of any masking or habitat impacts having
effects that would impact the reproduction or survival of any of the
individual marine mammals affected by the Action Proponents'
activities. Some odontocete stocks have predicted non-auditory injury
from explosives, discussed further below. Regarding the severity of
individual takes by Level B harassment by behavioral disturbance for
odontocetes, the majority of these responses are anticipated to occur
at received levels below 178 dB for most odontocete species and below
154 dB for sensitive species (i.e., beaked whales and harbor porpoises,
for which a lower behavioral disturbance threshold is applied), and
last from a few minutes to a few hours, at most, with associated
responses most likely in the form of moving away from the source,
foraging interruptions, vocalization changes, or disruption of other
social behaviors, lasting from a few minutes to several hours. Much of
the discussion below focuses on the behavioral effects and the
mitigation measures that reduce the probability or severity of effects
in biologically important areas or other habitats. Because there are
multiple stock-specific factors in relation to the status of the
species, as well as mortality take for several stocks, at the end of
the section we break out stock- or group-specific findings.
In table 91 (sperm whales, dwarf sperm whales, and pygmy sperm
whales), table 93 (beaked whales), table 95 (dolphins and small
whales), table 97 (porpoises), and table 99 (pinnipeds) below, we
indicate the total annual mortality, Level A harassment, and Level B
harassment, and a number indicating the instances of total take as a
percentage of abundance.
In table 92 (sperm whales, dwarf sperm whales, and pygmy sperm
whales), table 94 (beaked whales), table 96 (dolphins and small
whales), table 98 (porpoises), and table 100 (pinnipeds), below, we
indicate the status, life history traits, important habitats, and
threats that inform our analysis of the potential impacts of the
estimated take on the affected odontocete stocks.

[[Page 32311]]

Table 91--Annual Estimated Take by Level B Harassment, Level A harassment, and Mortality and Related Information for Pacific Stocks of Sperm Whale, Dwarf Sperm Whale, and Pygmy Sperm Whale in
the HCTT Study
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
annual
Maximum Maximum Maximum Maximum harassment Season(s) with 50 Region(s) with 40
Marine mammal species Stock NMFS stock NMSDD annual annual annual annual as percent of take or percent of take or
abundance abundance Level B Level A mortality take percentage greater greater
harassment harassment of stock
abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm Whale........................ Hawaii............... 5,707 6,062 1,649 1 0.14 1,650 27 Cold (55 percent).... HRC (94 percent).
Sperm Whale........................ California/Oregon/ 2,606 4,549 3,891 3 0 3,894 86 Cold (55 percent).... SOCAL (70 percent).
Washington.
Dwarf Sperm Whale.................. Hawaii............... UNK 43,246 45,224 915 0 46,139 107 Cold (54 percent).... HRC (93 percent).
Dwarf Sperm Whale.................. California/Oregon/ UNK 2,462 5,664 94 0 5,758 234 Cold (57 percent).... SOCAL (75 percent).
Washington.
Pygmy Sperm Whale.................. Hawaii............... 42,083 48,589 45,787 936 0 46,723 96 Cold (54 percent).... HRC (93 percent).
Pygmy Sperm Whale.................. California/Oregon/ 4,111 2,462 5,615 107 0 5,722 139 Cold (59 percent).... SOCAL (74 percent).
Washington.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UNK = Unknown. NMSDD abundances are averages only within the U.S. EEZ.
* Indicates which abundance estimate was used to calculate the maximum annual take as a percentage of abundance, either the NMFS SARs (Carretta et al., 2024; Young, 2024) or the NMSDD (table
2.4-1 in appendix A of the application). Please refer to the Odontocetes section for details on which abundance estimate was selected.

[[Page 32312]]

Table 92--Life History Traits, Important Habitat, and Threats to Sperm Whale, Dwarf Sperm Whale, and Pygmy Sperm Whale in the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annual
BIAs II for Hawaii mortality/
(Kratofil et al., serious
Marine mammal species Stock ESA status MMPA status Movement ecology Body size Reproductive Pace of life Chronic risk UME, oil spill, ESA- designated 2023) and West Population PBR injury
strategy factors other critical habitat Coast trend (from other
(Calambokidis et human
al., 2024) activities)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm Whale.................... Hawaii............ Endangered....... Depleted, Resident-migratory Large........... Income......... Slow......... Vessel strikes, No............. No.............. No................ Unk............ 18 0
Strategic. fisheries
interactions,
ocean noise,
marine debris,
disease.
Sperm Whale.................... California/Oregon/ Endangered....... Depleted, Migratory-resident Large........... Income......... Slow......... Vessel strikes, No............. No.............. No................ Stable......... 4 0.52
Washington. Strategic. fisheries
interactions,
ocean noise,
marine debris,
disease.
Dwarf Sperm Whale.............. Hawaii............ Not listed....... Not depleted, not Migratory, Small-Med....... Income......... Fast......... Fisheries No............. No.............. Yes: S-BIA Parent Unk............ UND 0
strategic. nomadic, resident. interactions, and Child HI-Core.
marine debris,
ocean noise.
Dwarf Sperm Whale.............. California/Oregon/ Not listed....... Not depleted, not Migratory, Small-Med....... Income......... Fast......... Fisheries No............. No.............. No................ Unk............ UND 0
Washington. strategic. nomadic, resident. interactions,
marine debris,
ocean noise.
Pygmy Sperm Whale.............. Hawaii............ Not listed....... Not depleted, not Migratory, Small-Med....... Income......... Fast......... Fisheries No............. No.............. Yes: S-BIA O MN HI Unk............ 257 0
strategic. nomadic, resident. interactions,
marine debris,
ocean noise.
Pygmy Sperm Whale.............. California/Oregon/ Not listed....... Not depleted, not Migratory, Small-Med....... Income......... Fast......... Fisheries No............. No.............. No................ Unk............ 19.2 0
Washington. strategic. nomadic, resident. interactions,
marine debris,
ocean noise.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UND = Undetermined, Unk = Unknown.

[[Page 32313]]

Sperm Whales, Dwarf Sperm Whales, and Pygmy Sperm Whales--
Sperm Whale (Hawaii and CA/OR/WA Stocks)
Sperm whales are listed as endangered under the ESA and are
considered depleted and strategic under the MMPA. The Navy's NMSDD
estimate for the Hawaii stock is 6,062 animals and for the CA/OR/WA
stock is 4,549 animals. There are no UMEs or other factors that cause
particular concern for these stocks, and there are no known
biologically important areas for the sperm whales in the HCTT Study
Area. Sperm whales generally have higher abundances in deep water and
areas of high productivity and are somewhat migratory, but their
movement ecology is demographically dependent. The Hawaii stock is
residential and occurs in Hawaiian waters year-round, while the CA/OR/
WA stock is somewhat migratory, with some individuals leaving warm
waters in summer to travel north to their arctic feeding grounds and
returning south in the fall and winter. Sperm whales face several
chronic anthropogenic and non-anthropogenic risk factors, including
vessel strike, fisheries interactions, pollution, ocean noise, and
disease, among others.
As shown in table 91, the maximum annual allowable instances of
take under this proposed rule by Level A harassment and Level B
harassment is 1 (Hawaii stock) and 3 (CA/OR/WA stock), and 1,649
(Hawaii stock) to 3,891 (CA/OR/WA stock), respectively. As indicated,
the rule also allows for up to one take by serious injury or mortality
of Hawaii sperm whales over the course of the 7-year rule, the impacts
of which are discussed above in the Serious Injury and Mortality
section. The total take allowable for each stock across all 7 years of
the rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with sperm whale communication or other important low-frequency cues.
Any associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 178 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Sperm whales
are large-bodied income breeders with a slow pace of life and are
likely more resilient to missed foraging opportunities due to acoustic
disturbance than smaller odontocetes. However, they may be more
susceptible to impacts due to lost foraging opportunities during
reproduction, especially if they occur during lactation (Farmer et al.,
2018b). Further, as described in the Group and Species-Specific
Analyses section above and the Proposed Mitigation Measures section,
mitigation measures are expected to further reduce the potential
severity of impacts through real-time operational measures that
minimize higher level/longer duration exposures and time/area measures
that reduce impacts in high value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. For both stocks of sperm
whales, given the lower number of takes by harassment as compared to
the stock/species abundance (see table 91), and the absence of take
concentrated in areas in which animals are known to congregate, it is
unlikely that any individual sperm whales would be taken on more than a
limited number of days within a year and, therefore, the anticipated
behavioral disturbance is not expected to affect reproduction or
survival.
Given the magnitude and severity of the impacts discussed above to
sperm whales (considering annual take maxima and the total across 7
years) and their habitat, and in consideration of the required
mitigation measures and other information presented, the proposed take
by harassment is not expected to impact the reproduction or survival of
any individuals nor, as described previously, is the mortality proposed
for authorization expected to adversely affect the species or stock.
For these reasons, we have determined that the take anticipated and
proposed for authorization would have a negligible impact on the Hawaii
and CA/OR/WA stocks of sperm whale.
Dwarf Sperm Whale (Hawaii and CA/OR/WA Stocks) and Pygmy Sperm Whale
(Hawaii and CA/OR/WA Stocks)
Neither dwarf sperm whales nor pygmy sperm whales are listed under
the ESA, and none of the stocks are considered depleted or strategic
under the MMPA. The current stock abundance of the CA/OR/WA stock of
pygmy sperm whale is 4,111 animals, and the stock abundances from
Navy's NMSDD are 2,426 (CA/OR/WA stock of dwarf sperm whale), 43,246
(Hawaii stock of dwarf sperm whale), and 48,589 (Hawaii stock of pygmy
sperm whale). There are no UMEs or other factors that cause particular
concern for these stocks. As described in the Description of Marine
Mammals and Their Habitat in the Area of the Specified Activities
section, the HCTT Study Area overlaps two known BIAs for small and
resident populations of the Hawaii stocks of dwarf and pygmy sperm
whale. Dwarf and pygmy sperm whales face several chronic anthropogenic
and non-anthropogenic risk factors, including fisheries interactions,
marine debris, and ocean noise, among others.
As shown in table 91, the maximum annual allowable instances of
take under this proposed rule by Level A Harassment and Level B
harassment is: 915 and 45,224 for the Hawaii stock of dwarf sperm
whale, respectively; 94 and 5,664 for the CA/OR/WA stock of dwarf sperm
whale, respectively; 936 and 45,787 for the Hawaii stock of pygmy sperm
whale, respectively; and 107 and 5,615 for the CA/OR/WA stock of pygmy
sperm whale, respectively. No mortality is anticipated or proposed for
authorization. The rule allows for a limited number of takes by non-
auditory injury (one each for the Hawaii stocks of dwarf and pygmy
sperm whales). As described above, given the limited number of
potential exposures and the anticipated effectiveness of the mitigation
measures in minimizing the pressure levels to which any individuals are
exposed, these injuries are unlikely to impact reproduction or
survival. The total take allowable across all 7 years of the rule is
indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be

[[Page 32314]]

lower-level, of short duration (from minutes to, at most, several hours
or less than a day), and mostly not in a frequency band that would be
expected to interfere with dwarf and pygmy sperm whale communication,
overlap more than a relatively narrow portion of the vocalization range
of any single species or stock, or preclude detection or interpretation
of important low-frequency cues. Any associated lost opportunities or
capabilities individuals might experience as a result of TTS would not
be at a level or duration that would be expected to impact reproductive
success or survival. For similar reasons, while auditory injury impacts
last longer, the low anticipated levels of AUD INJ that could be
reasonably expected to result from these activities are unlikely to
have any effect on fitness. The rule also allows for a limited number
of takes by non-auditory injury (one per stock) for the Hawaii stocks
of dwarf and pygmy sperm whales. As described above in the Auditory
Injury from Sonar Acoustic Sources and Explosives and Non-Auditory
Injury from Explosives section, given the limited number of potential
exposures and the anticipated effectiveness of the mitigation measures
in minimizing the pressure levels to which any individuals are exposed,
these non-auditory injuries are unlikely to be of a nature or level
that would impact reproduction or survival for either of the Hawaii
stocks of dwarf and pygmy sperm whales.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 178 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Dwarf and pygmy
sperm whales are small-to-medium-bodied income breeders with a fast
pace of life. They are generally more sensitive to missed foraging
opportunities than larger odontocetes, especially during lactation, but
would be quick to recover given their fast pace of life. Further, as
described in the Group and Species-Specific Analyses section above and
the Proposed Mitigation Measures section, mitigation measures are
expected to further reduce the potential severity of impacts through
real-time operational measures that minimize higher level/longer
duration exposures and time/area measures that reduce impacts in high
value habitat. In particular, this proposed rulemaking includes a
Hawaii Island Marine Mammal Mitigation Area, within which the Action
Proponents must not use more than 300 hours of MF1 surface ship hull-
mounted mid-frequency active sonar or 20 hours of helicopter dipping
sonar (a mid-frequency active sonar source) annually and must not
detonate in-water explosives (including underwater explosives and
explosives deployed against surface targets). These restrictions would
reduce exposure of numerous small and resident marine mammal
populations, including dwarf and pygmy sperm whales, to levels of sound
from sonar or explosives that have the potential to cause injury or
mortality, thereby reducing the likelihood of those effects and,
further, minimizing the severity of behavioral disturbance.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, given the
number of takes by harassment as compared to the stock/species
abundance (see table 91) and the fact that a portion of the takes occur
in BIAs for the Hawaii stocks, it is likely that some portion of the
individuals taken are taken repeatedly over a limited to moderate
number of days. However, given the variety of activity types that
contribute to take across separate exercises conducted at different
times and in different areas, and the fact that many result from
transient activities conducted at sea, it is unlikely that repeated
takes would occur either in numbers or clumped across sequential days
in a manner likely to impact foraging success and energetics or other
behaviors such that reproduction or survival of any individuals is
likely to be impacted.
Given the magnitude and severity of the impacts discussed above to
dwarf and pygmy sperm whale stocks in the HCTT Study Area (considering
annual take maxima and the total across 7 years) and their habitats,
and in consideration of the required mitigation measures and other
information presented, the Action Proponents' activities are not
expected to result in impacts on the reproduction or survival of any
individuals, much less affect annual rates of recruitment or survival.
For these reasons, we have determined that the take anticipated and
proposed for authorization would have a negligible impact on the Hawaii
and CA/OR/WA stocks of dwarf and pygmy sperm whales.
Beaked Whales--
This section builds on the broader odontocete discussion above
(i.e., that information applies to beaked whales as well), and brings
together the discussion of the different types and amounts of take that
different beaked whale species and stocks will likely incur, any
additional applicable mitigation, and the status of the species and
stocks to support the negligible impact determinations for each species
or stock.

Table 93--Annual Estimated Take by Level B Harassment, Level A Harassment, and Mortality and Related Information for Beaked Whales in the HCTT Study Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
annual
Maximum Maximum Maximum Maximum harassmen Season(s) with 50 Region(s) with 40
Marine mammal species Stock NMFS stock NMSDD annual annual annual annual as percent of take or percent of take or
abundance abundance Level B Level A mortality take percentage greater greater
harassment harassment of stock
abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Baird's Beaked Whale.............. California/Oregon/ 1,363 871 10,174 0 0 10,174 746 Cold (54 percent).... SOCAL (58 percent).
Washington.
Blainville's Beaked Whale......... Hawaii............... 1,132 1,300 7,542 0 0 7,542 580 Cold (55 percent).... HRC (94 percent).
Goose-Beaked Whale................ Hawaii............... 4,431 5,116 30,359 0 0 30,359 593 Cold (55 percent).... HRC (94 percent).
Goose-Beaked Whale................ California/Oregon/ 5,454 13,531 166,816 2 0 166,818 1233 Cold (54 percent).... SOCAL (82 percent).
Washington.

[[Page 32315]]

Longman's Beaked Whale............ Hawaii............... 2,550 2,940 18,316 1 0 18,317 623 Cold (56 percent).... HRC (94 percent).
Mesoplodont Beaked Whale.......... California/Oregon/ 3,044 7,534 92,839 2 0 92,841 1232 Cold (55 percent).... SOCAL (76 percent).
Washington.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UNK = Unknown. NMSDD abundances are averages only within the U.S. EEZ.
* Indicates which abundance estimate was used to calculate the maximum annual take as a percentage of abundance, either the NMFS SARs (Carretta et al., 2024; Young, 2024) or the NMSDD (table
2.4-1 in appendix A of the application). Please refer to the Odontocetes section for details on which abundance estimate was selected.

[[Page 32316]]

Table 94--Life History Traits, Important Habitat, and Threats to Beaked Whales in the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annual
BIAs II for Hawaii mortality/
ESA- designated (Kratofil et al., serious
Marine mammal species Stock ESA status MMPA status Movement ecology Body size Reproductive Pace of life Chronic risk UME, oil critical 2023) and West Population trend PBR injury
strategy factors spill, other habitat Coast (from other
(Calambokidis et human
al., 2024) activities)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Baird's Beaked Whale........... California/Oregon/ Not listed....... Not depleted, not Nomadic, resident. Large........ Mixed.............. Slow......... Fisheries No........... No............. No................ Stable, possibly 8.9 >=0.2
Washington. strategic. interactions, increasing.
ocean noise.
Blainville's Beaked Whale...... Hawaii............ Not listed....... Not depleted, not Nomadic, resident. Med.......... Mixed.............. Med.......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. 5.6 0
strategic. interactions, and Child O MN HI.
ocean noise.
Goose-Beaked Whale............. Hawaii............ Not listed....... Not depleted, not Nomadic, resident. Med.......... Mixed.............. Med.......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. 32 0
strategic. interactions, and Child HI-Core.
ocean noise.
Goose-Beaked Whale............. California/Oregon/ Not listed....... Not depleted, not Nomadic, resident. Med.......... Mixed.............. Med.......... Fisheries No........... No............. No................ Unk.............. 42 <0.1
Washington. strategic. interactions,
ocean noise.
Longman's Beaked Whale......... Hawaii............ Not listed....... Not depleted, not Nomadic-resident.. Med.......... Mixed.............. Med.......... Fisheries No........... No............. No................ Unk.............. 15 0
strategic. interactions,
ocean noise.
Mesoplodont Beaked Whale....... California/Oregon/ Not listed....... Not depleted, not Resident-nomadic.. Med.......... Mixed.............. Med.......... Fisheries No........... No............. No................ Unk, possibly 20 0.1
Washington. strategic. interactions, increasing.
ocean noise.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, Unk = Unknown.

[[Page 32317]]

These stocks are not listed as endangered or threatened under the
ESA, and they are not considered depleted or strategic under the MMPA.
The stock abundance estimates range from 1,300 (Hawaii stock of
Blainville's beaked whale, NMSDD) to 13,531 (CA/OR/WA stock of goose-
beaked whale, NMSDD). There are no UMEs or other factors that cause
particular concern for these stocks in the HCTT Study Area. As
described in the Description of Marine Mammals and Their Habitat in the
Area of the Specified Activities section, the HCTT Study Area overlaps
two known biologically important areas for small and resident
populations for the Hawaii stocks of Blainville's and goose-beaked
whales. Beaked whales face several chronic anthropogenic and non-
anthropogenic risk factors, including fisheries interactions, and ocean
noise, among others.
As shown in table 93, the maximum annual allowable instances of
take under this proposed rule by Level A harassment and Level B
Harassment range from 0 to 2, and 7,542 and 166,816, respectively. No
mortality is anticipated or proposed for authorization, nor is any non-
auditory injury. The total take allowable across all 7 years of the
rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with echolocation, overlap more than a relatively narrow portion of the
vocalization range of any single species or stock, or preclude
detection or interpretation of important low-frequency cues. Any
associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on fitness
on the CA/OR/WA stocks of goose- and mesoplodont beaked whales and the
Hawaii stock of Longman's beaked whales.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 154 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Beaked whales
are medium-to-large-bodied odontocetes with a medium pace of life and
likely moderately resilient to missed foraging opportunities due to
acoustic disturbance. They are mixed breeders (i.e., behaviorally
income breeders), and they demonstrate capital breeding strategies
during gestation and lactation (Keen et al., 2021), so they may be more
vulnerable to prolonged loss of foraging opportunities during
gestation. Further, as described in the Group and Species-Specific
Analyses section above and the Proposed Mitigation Measures section,
mitigation measures are expected to further reduce the potential
severity of impacts through real-time operational measures that
minimize higher level/longer duration exposures and time/area measures
that reduce impacts in high value habitat. In particular, this proposed
rulemaking includes a Hawaii Island Marine Mammal Mitigation Area,
within which the Action Proponents must not use more than 300 hours of
MF1 surface ship hull-mounted mid-frequency active sonar or 20 hours of
helicopter dipping sonar (a mid-frequency active sonar source) annually
and must not detonate in-water explosives (including underwater
explosives and explosives deployed against surface targets). These
restrictions would reduce exposure of numerous small and resident
marine mammal populations, including the Hawaii stocks of Blainville's
and goose-beaked whales, to levels of sound from sonar or explosives
that have the potential to cause injury or mortality, thereby reducing
the likelihood of those effects and, further, minimizing the severity
of behavioral disturbance.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, given the
number of takes by harassment as compared to the stock/species
abundance (see table 93), it is likely that some portion of the
individuals taken are taken repeatedly over a moderate number of days.
However, given the variety of activity types that contribute to take
across separate exercises conducted at different times and in different
areas, and the fact that many result from transient activities
conducted at sea, it is unlikely that repeated takes would occur
clumped across sequential days in a manner likely to impact foraging
success and energetics or other behaviors such that reproduction or
survival of any individuals is likely to be impacted.
Given the magnitude and severity of the impacts discussed above to
beaked whale stock/species (considering annual take maxima and the
total across 7 years) and their habitat, and in consideration of the
required mitigation measures and other information presented, the
Action Proponents' activities are not expected to result in impacts on
the reproduction or survival of any individuals, much less affect
annual rates of recruitment or survival. For these reasons, we have
determined that the take anticipated and proposed for authorization
would have a negligible impact on the CA/OR/WA stocks of Baird's,
goose-, and mesoplodont beaked whales, and the Hawaii stocks of
Blainville's, goose-, and Longman's beaked whale stocks.
Dolphins and Small Whales--
Of the 39 stocks of dolphins and small whales (Delphinidae) for
which incidental take is proposed for authorization (see table 95), one
is listed as endangered under the ESA and depleted and strategic under
the MMPA: the Main Hawaiian Islands Insular stock of false killer
whale. While not ESA-listed, the Hawaii Pelagic stock of false killer
whale is considered strategic under the MMPA. As shown in table 95 and
table 96, these delphinids vary in stock abundance, body size, and
movement ecology from, for example, the small-bodied, nomadic CA/OR/WA
stock of short-beaked common dolphin with NMSDD abundance estimate of
1,049,117, to the medium-sized small and resident Main Hawaiian Islands
Insular stock of false killer whale with an estimated abundance of 138.
The HCTT Study Area overlaps ESA-designated critical habitat for the
Main Hawaiian Islands Insular stock of false killer whale (83 FR 35062,
July 24, 2018), as well as BIAs for the following small and resident
populations: false killer whale (Main Hawaiian Islands Insular and
Northwest Hawaiian Islands stocks), melon-headed whale (Hawaiian
Islands and Kohala Resident stocks), short-finned pilot whale (Hawaii
stock), bottlenose dolphin (Maui Nui, Hawaii Island, Kaua[revaps]i/
Ni[revaps]ihau, and O[revaps]ahu stocks), pantropical spotted dolphins
(Maui Nui, Hawaii Island, and O[revaps]ahu stocks), rough-toothed
dolphin (Hawaii stock), and spinner dolphin (Hawaii Island,
Kaua[revaps]i/Ni[revaps]ihau, and O[revaps]ahu/4

[[Page 32318]]

Islands Region stocks). These areas are described in the Description of
Marine Mammals and Their Habitat in the Area of Specified Activities
section. Delphinids face a number of chronic anthropogenic and non-
anthropogenic risk factors including fishery interactions, biotoxins,
chemical contaminants, illegal feeding/harassment, ocean noise, oil
spills and energy exploration, vessel strikes, and swim with dolphin
programs, the impacts of which vary depending whether the stock is more
coastal (e.g., swim with dolphin programs occur mostly with coastally-
distributed spinner dolphins), more or less deep-diving (e.g.,
entanglement more common in deep divers like pygmy killer whales and
pilot whales), and other behavioral differences (e.g., vessels strikes
more concern for killer whales). There are no known UMEs or other
factors that cause particular concern for these stocks.

[[Page 32319]]

Table 95--Annual Estimated Take by Level B harassment, Level A Harassment, and Mortality and Related Information for Dolphins in the HCTT Study Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
annual Greatest degree
Maximum Maximum Maximum Maximum harassment Season(s) with Region(s) with any individual
Marine mammal species Stock NMFS stock NMSDD annual annual annual annual as 50 percent of 40 percent of expected to be
abundance abundance Level B Level A mortality take percentage take or greater take or greater taken repeatedly
harassment harassment of stock across multiple
abundance days
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
False Killer Whale............ Main Hawaiian 138 98 169 0 0 169 122 Warm (53 HRC (100 Limited number
Islands Insular. percent), Cold percent). of days.
(46 percent).
False Killer Whale............ Northwest 477 477 191 0 0 191 40 Cold (68 HRC (100 Limited number
Hawaiian Islands. percent). percent). of days.
False Killer Whale............ Hawaii Pelagic... 5,528 2,400 1,670 1 0 1,671 30 Cold (52 HRC (95 percent) Zero to limited
percent). number of days.
False Killer Whale............ Baja California N/A 1,990 2,537 2 0 2,539 128 Cold (58 SOCAL (100 Limited number
Peninsula Mexico. percent). percent). of days.
Killer Whale.................. Hawaii........... 161 198 127 0 0 127 64 Cold (51 HRC (95 percent) Zero to limited
percent). number of days.
Killer Whale.................. Eastern North 300 155 1,023 4 0 1,027 342 Cold (61 SOCAL (88 Limited to
Pacific Offshore. percent). percent). moderate number
of days.
Killer Whale.................. West Coast 349 26 55 0 0 55 16 Warm (56 NOCAL (58 Zero to limited
Transient. percent). percent). number of days.
Melon-Headed Whale............ Hawaiian Islands. 40,647 46,949 31,456 13 0 31,469 67 Cold (53 HRC (96 percent) Limited number
percent). of days.
Melon-Headed Whale............ Kohala Resident UNK 447 56 0 0 56 13 Warm (77 HRC (100 Zero to limited
(Hawaii). percent). percent). number of days.
Pygmy Killer Whale............ Hawaii........... 10,328 11,928 8,895 3 0 8,898 75 N/A............. HRC (95 percent) Zero to limited
number of days.
Pygmy Killer Whale............ California--Baja N/A 874 795 0 0 795 91 Warm (100 SOCAL (84 Zero to limited
California percent). percent). number of days.
Peninsula Mexico.
Short-Finned Pilot Whale...... Hawaii........... 19,242 23,117 17,304 7 0 17,311 75 Cold (53 HRC (97 percent) Limited number
percent). of days.
Short-Finned Pilot Whale...... California/Oregon/ 836 831 4,279 11 0.57 4,291 513 Cold (60 SOCAL (85 Moderate number
Washington. percent). percent). of days.
Bottlenose Dolphin............ Maui Nui......... 64 65 326 0 0 326 502 N/A............. HRC (100 Moderate number
percent). of days.
Bottlenose Dolphin............ Hawaii Island.... 136 138 9 0 0 9 7 Cold (80 HRC (100 Zero to limited
percent). percent). number of days.
Bottlenose Dolphin............ Hawaii Pelagic... 24,669 25,120 43,313 25 0.29 43,338 173 Cold (52 HRC (100 Limited number
percent). percent). of days.
Bottlenose Dolphin............ Kaua[revaps]i/ 112 113 1,460 0 0 1,460 1,292 Cold (59 HRC (100 High number of
Ni[revaps]ihau. percent). percent). days.
Bottlenose Dolphin............ O[revaps]ahu..... 112 113 7,232 6 0.14 7,238 6,405 Cold (54 HRC (100 High number of
percent). percent). days.
Bottlenose Dolphin............ California 453 182 1,350 7 0 1,357 300 Cold (60 SOCAL (98 Limited to
Coastal. percent). percent). moderate number
of days.
Bottlenose Dolphin............ California/Oregon/ 3,477 42,395 28,058 15 0 28,073 66 Warm (65 SOCAL (93 Zero to limited
Washington percent). percent). number of days.
Offshore.
Fraser's Dolphin.............. Hawaii........... 40,960 47,288 35,480 8 0 35,488 75 Cold 51 percent) HRC (97 percent) Zero to limited
number of days.
Long-Beaked Common Dolphin.... California....... 83,379 209,100 296,878 152 2.43 297,032 142 Warm (54 SOCAL (82 Limited number
percent). percent). of days.
Northern Right Whale Dolphin.. California/Oregon/ 29,285 68,935 45,514 21 0.14 45,535 66 Cold (75 NOCAL (41 Zero to limited
Washington. percent). percent). number of days.
Pacific White-Sided Dolphin... California/Oregon/ 34,999 107,775 69,210 42 0.29 69,252 64 Cold (59 SOCAL (53 Zero to limited
Washington. percent). percent). number of days.
Pantropical Spotted Dolphin... Maui Nui......... UNK 2,674 2,373 4 0 2,377 89 N/A............. HRC (100 Limited number
percent). of days.
Pantropical Spotted Dolphin... Hawaii Island.... UNK 8,674 6,024 7 0 6,031 70 Warm (51 HRC (100 Limited number
percent). percent). of days.

[[Page 32320]]

Pantropical Spotted Dolphin... Hawaii Pelagic... 67,313 62,395 44,390 19 0 44,409 71 Cold (55 HRC (97 percent) Zero to limited
percent). number of days.
Pantropical Spotted Dolphin... O[revaps]ahu..... UNK 1,491 6,426 6 0 6,432 431 Warm (51 HRC (100 Moderate number
percent). percent). of days.
Pantropical Spotted Dolphin... Baja California N/A 70,889 97,626 47 0.29 97,673 138 Cold (55 SOCAL (100 Limited number
Peninsula Mexico. percent). percent). of days.
Risso's Dolphin............... Hawaii........... 6,979 8,649 6,558 4 0 6,562 76 N/A............. HRC (95 percent) Zero to limited
number of days.
Risso's Dolphin............... California/Oregon/ 6,336 19,357 43,833 21 0 43,854 227 Cold (54 SOCAL (87 Limited to
Washington. percent). percent). moderate number
of days.
Rough-Toothed Dolphin......... Hawaii........... 83,915 106,193 96,873 36 0.29 96,909 91 Cold (53 HRC (97 percent) Limited number
percent). of days.
Short-Beaked Common Dolphin... California/Oregon/ 1,056,308 1,049,117 2,169,554 877 15.29 2,170,446 207 Warm (53 SOCAL (82 Limited to
Washington. percent). percent). moderate number
of days.
Spinner Dolphin............... Hawaii Pelagic... N/A 6,807 4,544 2 0 4,546 67 Cold (54 HRC (95 percent) Zero to limited
percent). number of days.
Spinner Dolphin............... Hawaii Island.... 665 670 110 1 0 111 17 Warm (60 HRC (100 Zero to limited
percent). percent). number of days.
Spinner Dolphin............... Kaua[revaps]i/ N/A 606 4,446 2 0 4,448 734 Cold (65 HRC (100 Moderate number
Ni[revaps]ihau. percent). percent). of days.
Spinner Dolphin............... O[revaps]ahu/4 N/A 355 1,201 1 0 1,202 339 Warm (63 HRC (100 Limited to
Islands Region. percent). percent). moderate number
of days.
Striped Dolphin............... Hawaii Pelagic... 64,343 68,909 37,782 12 0 37,794 55 Cold (53 HRC (95 percent) Zero to limited
percent). number of days.
Striped Dolphin............... California/Oregon/ 29,988 160,551 133,399 44 0.14 133,443 83 Warm (55 SOCAL (87 Zero to limited
Washington. percent). percent). number of days.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UNK = Unknown. NMSDD abundances are averages only within the U.S. EEZ.
* Indicates which abundance estimate was used to calculate the maximum annual take as a percentage of abundance, either the NMFS SARs (Carretta et al., 2024; Young, 2024) or the NMSDD (table
2.4-1 in appendix A of the application). Please refer to the Odontocetes section for details on which abundance estimate was selected.

Table 96--Life History Traits, Important Habitat, and Threats to Dolphins in the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annual
BIAs II for mortality/
ESA- designated Hawaii (Kratofil serious
Marine mammal species Stock ESA status MMPA status Movement ecology Body size Reproductive Pace of life Chronic risk UME, oil critical et al., 2023) and Population trend PBR injury
strategy factors spill, other habitat West Coast (from other
(Calambokidis et human
al., 2024) activities)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
False Killer Whale............. Main Hawaiian Endangered....... Depleted, Resident-nomadic.. Med.......... Income............. Med.......... Fisheries No........... Yes............ Yes: S-BIA Parent Decreasing....... 0.3 0.1
Islands Insular. Strategic. interactions, and Child MHI-
contaminants. Core.
False Killer Whale............. Northwest Hawaiian Not listed....... Not depleted, not Resident, nomadic. Med.......... Income............. Med.......... Fisheries No........... No............. Yes: S-BIA....... Unk.............. 1.43 0.16
Islands. strategic. interactions,
contaminants.

[[Page 32321]]

False Killer Whale............. Hawaii Pelagic.... Not listed....... Not depleted, Nomadic........... Med.......... Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 36 47
Strategic. interactions,
contaminants.
False Killer Whale............. Baja California N/A.............. N/A............... Unk............... Med.......... Income............. Med.......... Fisheries No........... No............. No............... Unk.............. ...... ...........
Peninsula Mexico. interactions,
contaminants.
Killer Whale................... Hawaii............ Not listed....... Not depleted, not Nomadic........... Large........ Income............. Slow......... Fisheries No........... No............. No............... Unk.............. 0.8 0
strategic. interactions.
Killer Whale................... Eastern North Not listed....... Not depleted, not Nomadic........... Large........ Income............. Slow......... Fisheries No........... No............. No............... Stable........... 2.8 0
Pacific Offshore. strategic. interactions,
vessel strikes,
ocean noise.
Killer Whale................... West Coast Not listed....... Not depleted, not Nomadic........... Large........ Income............. Slow......... Fisheries No........... No............. No............... Unk.............. 3.5 0.4
Transient. strategic. interactions,
vessel strikes,
ocean noise.
Melon-Headed Whale............. Hawaiian Islands.. Not listed....... Not depleted, not Resident-nomadic.. Small........ Income............. Med.......... Fisheries No........... No............. Yes: S-BIA....... Unk.............. 233 0
strategic. interactions,
ocean noise.
Melon-Headed Whale............. Kohala Resident Not listed....... Not depleted, not Resident.......... Small........ Income............. Med.......... Fisheries No........... No............. Yes: S-BIA....... Unk.............. UND 0
(Hawaii). strategic. interactions,
ocean noise.
Pygmy Killer Whale............. Hawaii............ Not listed....... Not depleted, not Resident, nomadic. Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 59 0
strategic. interactions,
ocean noise.
Pygmy Killer Whale............. California--Baja N/A.............. N/A............... Unk............... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. ...... ...........
California interactions,
Peninsula Mexico. ocean noise.
Short-Finned Pilot Whale....... Hawaii............ Not listed....... Not depleted, not Nomadic........... Med.......... Income............. Slow......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. 159 0.2
strategic. interactions. and Child MHI-
Western
community,
Central
community,
Eastern
community.
Short-Finned Pilot Whale....... California/Oregon/ Not listed....... Not depleted, not Nomadic........... Med.......... Income............. Slow......... Fisheries No........... No............. No............... Unk.............. 4.5 1.2
Washington. strategic. interactions.
Bottlenose Dolphin............. Maui Nui.......... Not listed....... Not depleted, not Resident.......... Small-Med.... Income............. Med.......... Entanglement...... No........... No............. Yes: S-BIA Parent Unk.............. 0.6 UNK
strategic. and Child.
Bottlenose Dolphin............. Hawaii Island..... Not listed....... Not depleted, not Resident.......... Small-Med.... Income............. Med.......... Fisheries No........... No............. Yes: S-BIA....... Unk.............. 1 >0.2
strategic. interactions.

[[Page 32322]]

Bottlenose Dolphin............. Hawaii Pelagic.... Not listed....... Not depleted, not Nomadic........... Small-Med.... Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 158 0
strategic. interactions.
Bottlenose Dolphin............. Kaua[revaps]i/ Not listed....... Not depleted, not Resident.......... Small-Med.... Income............. Med.......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. 0.9 UNK
Ni[revaps]ihau. strategic. interactions. and Child.
Bottlenose Dolphin............. O[revaps]ahu...... Not listed....... Not depleted, not Resident.......... Small-Med.... Income............. Med.......... Entanglement...... No........... No............. Yes: S-BIA Parent Unk.............. 1 UNK
strategic. and Child.
Bottlenose Dolphin............. California Coastal Not listed....... Not depleted, not Nomadic........... Small-Med.... Income............. Med.......... Biotoxins, No........... No............. No............... Stable, possibly 2.7 >=2.0
strategic. chemical increasing.
contaminants,
fisheries
interactions,
habitat
alteration,
illegal feeding
and harassment,
ocean noise, oil
spills and energy
exploration,
vessel strikes.
Bottlenose Dolphin............. California/Oregon/ Not listed....... Not depleted, not Nomadic........... Small-Med.... Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 19.7 >=0.82
Washington strategic. interactions.
Offshore.
Fraser's Dolphin............... Hawaii............ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Fast......... Fisheries No........... No............. No............... Unk.............. 241 0
strategic. interactions.
Long-Beaked Common Dolphin..... California........ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 668 >=29.7
strategic. interactions,
exposure to
underwater
detonations in
coastal waters.
Northern Right Whale Dolphin... California/Oregon/ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 163 >=6.6
Washington. strategic. interactions.

[[Page 32323]]

Pacific White-Sided Dolphin.... California/Oregon/ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Entanglement, No........... No............. No............... Unk.............. 279 7
Washington. strategic. fisheries
interactions.
Pantropical Spotted Dolphin.... Maui Nui.......... Not listed....... Not depleted, not Resident.......... Small........ Income............. Med.......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. UND UNK
strategic. interactions. and Child.
Pantropical Spotted Dolphin.... Hawaii Island..... Not listed....... Not depleted, not Resident.......... Small........ Income............. Med.......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. UND UNK
strategic. interactions. and Child.
Pantropical Spotted Dolphin.... Hawaii Pelagic.... Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 538 0
strategic. interactions.
Pantropical Spotted Dolphin.... O[revaps]ahu...... Not listed....... Not depleted, not Resident.......... Small........ Income............. Med.......... Fisheries No........... No............. Yes: S-BIA Parent Unk.............. UND UNK
strategic. interactions. and Child.
Pantropical Spotted Dolphin.... Baja California N/A.............. N/A............... Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. UNK UNK
Peninsula Mexico. interactions.
Risso's Dolphin................ Hawaii............ Not listed....... Not depleted, not Nomadic........... Small-Med.... Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 53 0
strategic. interactions.
Risso's Dolphin................ California/Oregon/ Not listed....... Not depleted, not Nomadic........... Small-Med.... Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 46 >=3.7
Washington. strategic. interactions.
Rough-Toothed Dolphin.......... Hawaii............ Not listed....... Not depleted, not Resident, nomadic. Small........ Income............. Med.......... Fisheries No........... No............. Yes: S-BIA MNHI, Unk.............. 511 3.2
strategic. interactions. Parent and Child
KN O.
Short-Beaked Common Dolphin.... California/Oregon/ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk, possibly 8,889 >=30.5
Washington. strategic. interactions, increasing.
exposure to
underwater
detonations in
coastal waters.
Spinner Dolphin................ Hawaii Pelagic.... Not listed....... Not depleted, not Nomadic........... Small........ Income............. Fast......... Fisheries No........... No............. No............... Unk.............. UND 0
strategic. interactions,
ocean noise.
Spinner Dolphin................ Hawaii Island..... Not listed....... Not depleted, not Nomadic........... Small........ Income............. Fast......... Swim with the No........... No............. Yes: S-BIA....... Unk.............. 6.2 >=1.0
strategic. dolphin programs,
ocean noise,
fisheries
interactions.

[[Page 32324]]

Spinner Dolphin................ Kaua[revaps]i/ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Fast......... Swim with the No........... No............. Yes: S-BIA....... Unk.............. UND UNK
Ni[revaps]ihau. strategic. dolphin programs,
ocean noise,
fisheries
interactions.
Spinner Dolphin................ O[revaps]ahu/4 Not listed....... Not depleted, not Nomadic........... Small........ Income............. Fast......... Swim with the No........... No............. Yes: S-BIA....... Unk.............. UND >=0.4
Islands Region. strategic. dolphin programs,
ocean noise,
fisheries
interactions.
Striped Dolphin................ Hawaii Pelagic.... Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 511 0
strategic. interactions.
Striped Dolphin................ California/Oregon/ Not listed....... Not depleted, not Nomadic........... Small........ Income............. Med.......... Fisheries No........... No............. No............... Unk.............. 225 >=4
Washington. strategic. interactions.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UND = Undetermined, Unk = Unknown.

[[Page 32325]]

As shown in table 95, the maximum annual allowable instances of
take by Level B harassment for delphinid stocks ranges from 9 (Hawaii
Island stock of bottlenose dolphin) to 2,169,554 for the CA/OR/WA stock
of short-beaked common dolphin, with 14 stocks below 2,000, five stocks
above 70,000, and the remainder between 2,000 and 70,000. Take by Level
A harassment is 0 for 9 of the 39 stocks, between 1 and 15 for 20
stocks, and above 15 for 10 stocks. As indicated, the rule also allows
for take by M/SI for 10 stocks (the CA/OR/WA stocks of short-finned
pilot whale, northern right whale dolphin, Pacific white-sided dolphin,
short-beaked common dolphin, and striped dolphin; the Hawaii Pelagic
and O[revaps]ahu stocks of bottlenose dolphin; the California stock of
long-beaked common dolphin; the Baja California Peninsula Mexico
population of pantropical spotted dolphin; and the Hawaii stock of
rough-toothed dolphin), the impacts of which are discussed above in the
Serious Injury and Mortality section. The total take allowable across
all 7 years of the rule is indicated in table 54.
All delphinid stocks are expected to incur some number of takes in
the form of TTS. As described in the Auditory Injury from Sonar
Acoustic Sources and Explosives and Non-Auditory Injury from Explosives
section above, these temporary hearing impacts are expected to be
lower-level, of short duration (from minutes to at most several hours
or less than a day), and mostly not in a frequency band that would be
expected to interfere with delphinid echolocation, overlap more than a
relatively narrow portion of the vocalization range of any single
species or stock, or preclude detection or interpretation of important
low-frequency cues. Any associated lost opportunities or capabilities
individuals might experience as a result of TTS would not be at a level
or duration that would be expected to impact reproductive success or
survival. About three-quarters of the affected delphinid stocks will
incur some number of takes by AUD INJ, over half of those stocks will
incur take in the single digits, with only two stocks exceeding 45
(long- and short-beaked common dolphin). For reasons similar to those
discussed for TTS, while auditory injury impacts last longer, given the
anticipated effectiveness of mitigation measures and the likelihood
that individuals are expected to avoid higher levels associated with
more severe impacts, the lower anticipated levels of AUD INJ that could
be reasonably expected to result from these activities are unlikely to
affect the fitness of any individuals. Two stocks are projected to
incur notably higher numbers of take by AUD INJ (128 for the California
stock of long-beaked common dolphin and 806 for the CA/OR/WA stock of
short-beaked common dolphin) and while the conclusions above are still
applicable, it is further worth noting that these two stocks have
relatively large abundances and limited annual mortality as compared to
PBR. The rule also allows for a limited number of takes by non-auditory
injury (i.e., 1-71) for 19 stocks (less than 5 takes for all stocks
except for the California stock of long-beaked common dolphin and the
CA/OR/WA stock of short-beaked common dolphin). As described above in
the Auditory Injury from Sonar Acoustic Sources and Explosives and Non-
Auditory Injury from Explosives section, given the limited number of
potential exposures and the anticipated effectiveness of the mitigation
measures in minimizing the pressure levels to which any individuals are
exposed, these non-auditory injuries are unlikely to be of a nature or
level that would impact reproduction or survival, with the exception of
long- and short-beaked common dolphins.
Due to the larger number of long- and short-beaked common dolphin
individuals predicted to be exposed annually to levels associated with
non-auditory injury (24 and 71, respectively), it is more likely that
some subset of these individuals could potentially be injured in a
manner that would result in them foregoing reproduction for a year (up
to 4 long-beaked and 13 short-beaked common dolphins). A year of
foregone reproduction for a male is generally meaningless to population
rates unless the animal ultimately dies. M/SI have been modeled for
this activity separately, and NMFS does not anticipate that these non-
auditory injuries would result in mortality, for young or adults.
Neither stock is considered depleted or strategic. While the population
trends of these stocks are not known (though the SAR notes that the CA/
OR/WA stock of short-beaked common dolphin is possibly increasing),
they are not considered depleted or strategic, and total annual
mortality is well below PBR for each stock. Importantly, the increase
in a calving interval by a year would have far less of an impact on a
population rate than a mortality would and, accordingly, the number of
instances of foregone reproduction predicted here would not be expected
to adversely affect this stock through effects on annual rates of
recruitment or survival.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 178 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Delphinids are
income breeders with a medium pace of life, meaning that while they can
be sensitive to the consequences of disturbances that impact foraging
during lactation, from a population standpoint, they can be moderately
quick to recover. Further, as described in the Group and Species-
Specific Analyses section (and the Proposed Mitigation Measures
section), mitigation measures are expected to further reduce the
potential severity of impacts through real-time operational measures
that minimize higher level/longer duration exposures and time/area
measures that reduce impacts in higher value habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In the case of over half
of the delphinid stocks (see the ``Greatest degree any individual
expected to be taken repeatedly across multiple days'' column in table
95), given the low number of takes by harassment as compared to the
stock/species abundance alone, and also in consideration of their
nomadic movement pattern and whether take is concentrated in areas in
which animals are known to congregate, it is unlikely that these
individual delphinids would be taken on more than a limited number of
days within a year and, therefore, the anticipated behavioral
disturbance is not expected to affect reproduction or survival. In the
case of the rest of the stocks, given the number of takes by harassment
as compared to the stock/species abundance, it is likely that some
portion of the individuals taken are taken repeatedly over a small to
moderate number of days (as indicated in the ``Greatest degree any
individual expected to be taken repeatedly across multiple days''
column in table 95), with two stocks (Kaua[revaps]i/Ni[revaps]ihau and
O[revaps]ahu stocks of bottlenose dolphins) likely to be taken over a
high number of days. However, given the variety of activity types that
contribute to take across separate exercises conducted at

[[Page 32326]]

different times and in different areas, and the fact that many result
from transient activities conducted at sea, for all stocks except
Kaua[revaps]i/Ni[revaps]ihau and O[revaps]ahu stocks of bottlenose
dolphins (addressed below), it is unlikely that the anticipated small
to moderate number of repeated takes for a given individual would occur
clumped across sequential days in a manner likely to impact foraging
success and energetics or other behaviors such that reproduction or
survival of any individuals are likely to be impacted. Further, many of
these stocks are nomadic and, apart from the small resident
populations, there are no known foraging areas or other areas within
which delphinids are known to congregate for important behaviors, and
for most stocks, the takes are not concentrated within a specific
region and season.
Regarding the magnitude of repeated takes for the Kaua[revaps]i/
Ni[revaps]ihau and O[revaps]ahu stocks of bottlenose dolphins, given
the number of takes by harassment as compared to the stock/species
abundance and the small resident populations, it is more likely that
some number of individuals would experience a comparatively higher
number of repeated takes over a potentially fair number of sequential
days. Due to the higher number of repeated takes focused within the
stocks' limited ranges, it is thereby more likely that a portion of the
individuals (approximately 50 percent of which would be female) could
be repeatedly interrupted during foraging in a manner and amount such
that impacts to the energy budgets of a limited number of females (from
either losing feeding opportunities or expending considerable energy
moving away from sound sources or finding alternative feeding options)
could cause them to forego reproduction for a year (noting that
bottlenose dolphin calving intervals are typically 3 or more years).
Energetic impacts to males are generally meaningless to population
rates unless they cause death, and it takes extreme energy deficits
beyond what would ever be likely to result from these activities to
cause the death of an adult marine mammal, male or female. The
population trends of these stocks are unknown, and neither are
considered depleted or strategic. Importantly, the increase in a
calving interval by a year would have far less of an impact on a
population rate than a mortality would and, accordingly, a limited
number of instances of foregone reproduction would not be expected to
adversely affect these stocks through effects on annual rates of
recruitment or survival (noting also that no mortality is predicted or
authorized for the Kaua[revaps]i/Ni[revaps]ihau stock, and 0.14 annual
mortality is authorized for the O[revaps]ahu stock). Further, of note,
use of in-water explosives (including underwater explosives and
explosives deployed against surface targets) is prohibited within the
Hawaii 4-Islands Marine Mammal Mitigation Area. This measure would be
prevent exposure of these stocks to explosives that have the potential
to cause injury, mortality or behavioral disturbance within that area.
Further, within the same area, mitigation from November 15 to April 15
prohibiting use of MF1 surface ship hull-mounted mid-frequency active
sonar would reduce exposure of these stocks to levels of sound that
have the potential to cause injurious or behavioral impacts.
Given the magnitude and severity of the take by harassment
discussed above and any anticipated habitat impacts, and in
consideration of the required mitigation measures and other information
presented, the Action Proponents' activities are unlikely to result in
impacts on the reproduction or survival of any individuals of delphinid
stocks, with the exception of the 10 stocks for which takes by M/SI are
predicted and the 1 stock for which an increased calving interval could
potentially occur. Regarding the Kaua[revaps]i/Ni[revaps]ihau and
O[revaps]ahu stocks of bottlenose dolphins, as described above, we do
not anticipate the relatively limited number of individuals that might
be taken over repeated days within the year in a manner that results in
a year of foregone reproduction to adversely affect the stock through
effects on rates of recruitment or survival, given the status of the
stocks. Regarding the CA/OR/WA stock of short-finned pilot whale,
Hawaii Pelagic and O[revaps]ahu stocks of bottlenose dolphin,
California stock of long-beaked common dolphin, CA/OR/WA stock of
Northern right whale dolphin, CA/OR/WA stock of Pacific white-sided
dolphin, Baja California Peninsula Mexico population of pantropical
spotted dolphin, Hawaii stock of rough-toothed dolphin, CA/OR/WA stock
of short-beaked common dolphin, and CA/OR/WA stock of striped dolphin,
as described in the Serious Injury and Mortality section, given the
status of the stocks and in consideration of other ongoing
anthropogenic mortality (where known), the amount of allowed M/SI take
proposed here would not alone, nor in combination with the impacts of
the take by harassment discussed above (which are not expected to
impact the reproduction or survival of any individuals for those
stocks), be expected to adversely affect rates of recruitment and
survival. For these reasons, we have determined that the total take
(considering annual maxima and across 7 years) anticipated and proposed
for authorization would have a negligible impact on all delphinid
species and stocks.
Porpoises--
Neither Dall's porpoise nor harbor porpoise are listed as
endangered or threatened under the ESA, and none of the porpoise stocks
are considered depleted or strategic under the MMPA. The Navy's NMSDD
estimate for the CA/OR/WA stock of Dall's porpoise is 61,840, and the
stock abundances of harbor porpoises range from 3,885 (Navy's NMSDD) to
15,303 (SAR). There are no UMEs or other factors that cause particular
concern for this stock. As described in the Description of Marine
Mammals and Their Habitat in the Area of the Specified Activities
section, the HCTT Study Area overlaps two small and resident population
BIAs for the Monterey Bay and Morro Bay stocks of harbor porpoise
(Calambokidis et al., 2015). There is no ESA-designated critical
habitat for Dall's or harbor porpoise as neither species is ESA-listed.
Dall's porpoises can be found from Baja California, Mexico, to the
northern Bering Sea. They shift their distribution southward during
cooler-water periods on both interannual and seasonal time scales. They
primarily congregate in shelf and slope waters and decrease
substantially in waters warmer than 17[deg]C (63 [deg]F). Harbor
porpoises generally have higher abundances in shallow waters (less than
200 m (656 ft)) and near shore, but they sometimes move into deeper
offshore waters. However, this species has no overlap with nearshore or
offshore areas in the SOCAL Range Complex (e.g., San Diego, SOAR) or
the southern nearshore portions of PMSR (e.g., Port Hueneme). Dall's
and harbor porpoises face several chronic anthropogenic and non-
anthropogenic risk factors, including fishing gear, fisheries
interactions, and ocean noise (including acoustic deterrent devices or
``seal bombs'' in the case of harbor porpoises), among others.

[[Page 32327]]

Table 97--Annual Estimated Take by Level B harassment, Level A harassment, and Mortality and Related Information for Porpoises in the HCTT Study Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
annual
Maximum Maximum Maximum Maximum harassment Season(s) with 50 Region(s) with 40
Marine mammal species Stock NMFS stock NMSDD annual annual annual annual as percent of take or percent of take or
abundance abundance level B level A mortality take percentage greater greater
harassment harassment of stock
abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dall's Porpoise.................... California/Oregon/ 16,498 61,840 59,619 1,237 0 60,856 98 Cold (82 percent)..... SOCAL (48 percent)
Washington.
Harbor Porpoise.................... Monterey Bay.......... 3,760 4,530 2,179 0 0 2,179 48 Cold (71 percent)..... NOCAL (100 percent)
Harbor Porpoise.................... Morro Bay............. 4,191 3,885 4,373 88 0 4,461 115 Cold (74 percent)..... PMSR (99 percent)
Harbor Porpoise.................... Northern California/ 15,303 1,961 481 0 0 481 3 Cold (68 percent)..... NOCAL (100 percent)
Southern Oregon.
Harbor Porpoise.................... San Francisco/Russian 7,777 9,974 9,960 26 0 9,986 100 Cold (61 percent)..... NOCAL (100 percent)
River.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UNK = Unknown. NMSDD abundances are averages only within the U.S. EEZ.
* Indicates which abundance estimate was used to calculate the maximum annual take as a percentage of abundance, either the NMFS SARs (Carretta et al., 2024; Young, 2024) or the NMSDD (table
2.4-1 in appendix A of the application). Please refer to the Odontocetes section for details on which abundance estimate was selected.

Table 98--Life History Traits, Important Habitat, and Threats to Porpoises in the HCTT Study Area
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
BIAs II for
Hawaii Annual
Pace UME, Oil ESA- (Kratofil et Mortality/
Marine Mammal Species Stock ESA Status MMPA Status Movement Body Reproductive of Chronic Risk Spill, Designated al., 2023) and Population PBR Serious Injury
Ecology Size Strategy Life Factors Other Critical West Coast Trend (from other
Habitat (Calambokidis human
et al., 2024) activities)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Dall's Porpoise.............. California/ Not listed.... Not depleted, Nomadic....... Small.. Income........... Fast.. Fishing gear No....... No............ No............ Unk.......... 99 >=0.66
Oregon/ not strategic. fisheries
Washington. interactions.
Harbor Porpoise.............. Monterey Bay.... Not listed.... Not depleted, Resident...... Small.. Income........... Fast.. Fisheries No....... No............ Yes: S-BIA.... Increasing... 35 >=0.2
not strategic. interactions,
ocean noise
(including
acoustic
deterrent
devices or
``seal bombs'').
Harbor Porpoise.............. Morro Bay....... Not listed.... Not depleted, Resident...... Small.. Income........... Fast.. Fisheries No....... No............ Yes: S-BIA.... Increasing... 65 0
not strategic. interactions,
ocean noise
(including
acoustic
deterrent
devices or
``seal bombs'').
Harbor Porpoise.............. Northern Not listed.... Not depleted, Resident...... Small.. Income........... Fast.. Fisheries No....... No............ No............ Unk.......... 195 0
California/ not strategic. interactions,
Southern Oregon. ocean noise
(including
acoustic
deterrent
devices or
``seal bombs'').
Harbor Porpoise.............. San Francisco/ Not listed.... Not depleted, Resident...... Small.. Income........... Fast.. Fisheries No....... No............ No............ Stable....... 73 >=0.4
Russian River. not strategic. interactions,
ocean noise
(including
acoustic
deterrent
devices or
``seal bombs'').
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UND = Undetermined, Unk = Unknown.

[[Page 32328]]

As shown in table 97, the maximum annual allowable instances of
take of Dall's porpoise under this proposed rule by Level A harassment
and Level B harassment is 1,237 and 59,619, respectively, while the
maximum allowable take of harbor porpoise by Level A harassment and
Level B harassment is 88 (Morro Bay stock) and 9,960 (San Francisco/
Russian River stock), respectively. No mortality is anticipated or
proposed for authorization. The rule allows for a limited number of
takes by non-auditory injury (two for Dall's porpoise, one for the
Morro Bay stock of harbor porpoise). As described above, given the
limited number of potential exposures and the anticipated effectiveness
of the mitigation measures in minimizing the pressure levels to which
any individuals are exposed, these injuries are unlikely to impact
reproduction or survival. The total take allowable across all 7 years
of the rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as VHF cetaceans, Dall's and harbor porpoises are more susceptible to
auditory impacts in mid- to high frequencies and from explosives than
other species. As described in the Temporary Threshold Shift section
above, any takes in the form of TTS are expected to be lower-level, of
short duration (even the longest recovering in less than a day), and
mostly not in a frequency band that would be expected to interfere with
porpoise communication or other important auditory cues. Any associated
lost opportunities or capabilities individuals might experience as a
result of TTS would not be at a level or duration that would be
expected to impact reproductive success or survival. For similar
reasons, while auditory injury impacts last longer, the low anticipated
levels of AUD INJ that could be reasonably expected to result from
these activities are unlikely to have any effect on fitness. The rule
also allows for a limited number of takes by non-auditory injury for
Dall's porpoise and the Morro Bay stock of harbor porpoise (two and
one, respectively). As described above in the Auditory Injury from
Sonar Acoustic Sources and Explosives and Non-Auditory Injury from
Explosives section, given the limited number of potential exposures and
the anticipated effectiveness of the mitigation measures in minimizing
the pressure levels to which any individuals are exposed, these non-
auditory injuries are unlikely to be of a nature or level that would
impact reproduction or survival for these stocks.
Harbor porpoises are more susceptible to behavioral disturbance
than other species. They are highly sensitive to many sound sources and
generally demonstrate strong avoidance of most types of acoustic
stressors. The information currently available regarding harbor
porpoises suggests a very low threshold level of response for both
captive (Kastelein et al., 2000; Kastelein et al., 2005) and wild
(Johnston, 2002) animals. Southall et al. (2007) concluded that harbor
porpoises are likely sensitive to a wide range of anthropogenic sounds
at low received levels (approximately 90 to 120 dB). Research and
observations of harbor porpoises for other locations show that this
species is wary of human activity and will display profound avoidance
behavior for anthropogenic sound sources in many situations at levels
down to 120 dB re: 1 [micro]Pa (Southall et al., 2007). Harbor
porpoises routinely avoid and swim away from large, motorized vessels
(Barlow 1988; Evans et al., 1994; Palka and Hammond, 2001; Polacheck
and Thorpe, 1990). Accordingly, and as described in the Estimated Take
of Marine Mammals section, the threshold for behavioral disturbance is
lower for harbor porpoises, and the number of estimated takes is
higher, with many occurring at lower received levels than other taxa.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 154 dB SPL and last from a
few minutes to a few hours, at most. Associated responses would likely
include avoidance, foraging interruptions, vocalization changes, or
disruption of other social behaviors, lasting from a few minutes to
several hours and not likely to exceed 24 hours.
As small odontocetes and income breeders with a fast pace of life,
Dall's and harbor porpoises are less resilient to missed foraging
opportunities than larger odontocetes. Although reproduction in
populations with a fast pace of life are more sensitive to foraging
disruption, these populations are quick to recover. Further, as
described in the Group and Species-Specific Analyses section and the
Proposed Mitigation Measures section, mitigation measures are expected
to further reduce the potential severity of impacts through real-time
operational measures that minimize higher level/longer duration
exposures and time/area measures that reduce impacts in high value
habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. In this case, for the
Monterey Bay and Morro Bay stocks of harbor porpoise, given the number
of takes by harassment as compared to the stock/species abundance (see
table 97) and the small resident populations, it is likely that some
portion of the individuals taken are taken repeatedly over a limited
number of days. However, given the variety of activity types that
contribute to take across separate exercises conducted at different
times and in different areas, and the fact that many result from
transient activities conducted at sea, it is unlikely that repeated
takes would occur either in numbers or clumped across sequential days
in a manner likely to impact foraging success and energetics or other
behaviors such that reproduction or survival of any individuals is
likely to be impacted.
Given the magnitude and severity of the impacts discussed above to
Dall's porpoises and harbor porpoises (considering annual take maxima
and the total across 7 years) and their habitat, and in consideration
of the required mitigation measures and other information presented,
the Action Proponents' activities are unlikely to result in impacts on
the reproduction or survival of any individuals and, thereby, unlikely
to affect annual rates of recruitment or survival. For these reasons,
we have determined that the take by harassment anticipated and proposed
for authorization would have a negligible impact on Dall's porpoise and
all four stocks of harbor porpoises.
Pinnipeds
This section builds on the broader discussion above and brings
together the discussion of the different types and amounts of take that
different pinniped stocks will incur, the applicable mitigation for
each stock, and the status and life history of the stocks to support
the negligible impact determinations for each. We have already
described above why we believe the incremental addition of the moderate
number of low-level auditory injury takes will not have any meaningful
effect towards inhibiting reproduction or survival. We have also
described above in this section the unlikelihood of any masking or
habitat impacts having effects that would impact the reproduction or
survival of any of the individual marine mammals affected by the Action
Proponents' activities. Regarding the severity of individual takes by
Level B harassment by behavioral disturbance for pinnipeds, the
majority of these

[[Page 32329]]

responses are anticipated to occur at received levels below 172 dB, and
last from a few minutes to a few hours, at most, with associated
responses most likely in the form of moving away from the source,
foraging interruptions, vocalization changes, or disruption of other
social behaviors, lasting from a few minutes to several hours.
In table 99 below for pinnipeds, we indicate the total annual
mortality, Level A harassment, and Level B harassment, and a number
indicating the instances of total take as a percentage of abundance. In
table 100 below, we indicate the status, life history traits, important
habitats, and threats that inform our analysis of the potential impacts
of the estimated take on the affected pinniped stocks.

Table 99--Annual Estimated Take by Level B Harassment, Level A Harassment, and Mortality and Related Information for Pinnipeds in the HCTT Study Area
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
annual
Maximum Maximum Maximum Maximum harassment Season(s) with 50 Region(s) with 40
Marine mammal species Stock NMFS stock NMSDD annual annual annual annual as percent of take or percent of take or
abundance abundance Level B Level A mortality take percentage greater greater
harassment harassment of stock
abundance
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion............... U.S.................. 257,606 199,121 1,899,749 723 3.86 1,900,476 738 Cold (53 percent).... SOCAL (74 percent).
Guadalupe Fur Seal................ Mexico............... 63,850 48,780 347,553 54 0.14 347,607 544 N/A.................. SOCAL (82 percent).
Northern Fur Seal................. Eastern Pacific...... 612,765 89,110 33,195 12 0 33,207 5 Cold (86 percent).... NOCAL (47 percent),
PMSR (53 percent).
Northern Fur Seal................. California........... 19,634 14,115 22,098 10 0 22,108 113 Cold (58 percent).... PMSR (71 percent).
Steller Sea Lion.................. Eastern.............. 36,308 3,181 999 3 0 1,002 3 Cold (56 percent).... NOCAL (48 percent),
SOCAL (49 percent).
Harbor Seal....................... California........... 30,968 13,343 71,463 261 1.00 71,725 232 N/A.................. SOCAL (92 percent).
Hawaiian Monk Seal................ Hawaii............... 1,605 967 1,104 6 0 1,110 69 Cold (54 percent).... HRC (99 percent).
Northern Elephant Seal............ California Breeding.. 194,907 49,526 118,514 111 0 118,625 61 Cold (62 percent).... SOCAL (57 percent).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UNK = Unknown. NMSDD abundances are averages only within the U.S. EEZ.
* Indicates which abundance estimate was used to calculate the maximum annual take as a percentage of abundance, either the NMFS SARs (Carretta et al., 2024; Young, 2024) or the NMSDD (table
2.4-1 in appendix A of the application). Please refer to the Pinnipeds section for details on which abundance estimate was selected.

[[Page 32330]]

Table 100--Life History Traits, Important Habitat, and Threats to Pinnipeds in the HCTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annual
BIAs II for Hawaii mortality/
ESA- designated (Kratofil et al., serious
Marine mammal species Stock ESA status MMPA status Movement ecology Body size Reproductive Pace of life Chronic risk UME, oil critical 2023) and West Population PBR injury
strategy factors spill, other habitat Coast trend (from other
(Calambokidis et human
al., 2024) activities)
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion............ U.S............... Not listed....... Not depleted, not Resident-migratory Small........ Income............. Fast......... Fisheries No........... No............. No................ Stable........ 14,011 >321
strategic. interactions,
power plant
entrainment,
illegal
harassment,
habitat
degradation,
vessel strike,
chemical
contaminants.
Guadalupe Fur Seal............. Mexico............ Threatened....... Depleted, Migratory......... Small........ Income............. Fast......... Fisheries No........... No............. No................ Increasing.... 1,959 >=10.0
Strategic. interactions,
intentional
illegal killing/
harassment.
Northern Fur Seal.............. Eastern Pacific... Not listed....... Depleted, Migratory......... Small........ Income............. Fast......... Fisheries No........... No............. No................ Decreasing.... 11,151 296
Strategic. interactions,
intentional
killing/
harassment,
chemical
contaminants.
Northern Fur Seal.............. California........ Not listed....... Not depleted, not Resident.......... Small........ Income............. Fast......... Fisheries No........... No............. No................ Variable...... 527 >=1.2
strategic. interactions.
Steller Sea Lion............... Eastern........... Not listed....... Not depleted, not Resident.......... Small........ Income............. Fast......... Fisheries No........... No............. No................ Increasing.... 2,178 93.2
strategic. interactions,
harassment/.
Harbor Seal.................... California........ Not listed....... Not depleted, not Resident.......... Small........ Capital............ Fast......... Disturbance at No........... No............. No................ Decreasing.... 1,641 43
strategic. rookeries,
commercial
aquaculture,
illegal
intentional
killing, chemical
contaminants.
Hawaiian Monk Seal............. Hawaii............ Endangered....... Depleted, Resident.......... Small........ Capital............ Fast......... Fisheries No........... Yes............ No................ Increasing.... 5.3 >=4.8
Strategic. interactions,
illegal
harassment,
habitat
degradation.
Northern Elephant Seal......... California Not listed....... Not depleted, not Migratory......... Small-Med.... Capital............ Fast......... Fisheries No........... No............. No................ Increasing.... 5,328 11.2
Breeding. strategic. interactions,
illegal
harassment,
chemical
contaminants.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, UND = Undetermined, Unk = Unknown.

[[Page 32331]]

The Hawaiian monk seal (a NMFS Species in the Spotlight) and
Guadalupe fur seal are listed as endangered and threatened,
respectively, under the ESA and are considered depleted and strategic
under the MMPA. Northern fur seals are not listed as endangered or
threatened under the ESA, but the Eastern Pacific stock is considered
depleted and strategic under the MMPA. The remaining pinniped stocks
for which incidental take is proposed for authorization (see table 99)
are neither ESA-listed nor considered depleted or strategic under the
MMPA.
As shown in table 99 and table 100, these pinnipeds vary in stock
abundance and movement ecology from, for example, the resident Hawaii
stock of Hawaiian monk seal with an estimated abundance of 1,605
animals to the migratory Eastern Pacific stock of Northern fur seal
with an estimated abundance of 612,765 animals. The HCTT Study Area
overlaps the Hawaiian monk seal ESA-designated critical habitat (51 FR
16047, April 30, 1986; 53 FR 18988, May 26, 1988; 80 FR 50925, August
21, 2015), as described in the Description of Marine Mammals in the
Area of Specified Activities section, and there are no known BIAs for
pinnipeds that overlap the HCTT Study Area. There are no UMEs or other
factors that cause additional concern for these stocks. Pinnipeds face
a number of chronic anthropogenic and non-anthropogenic risk factors
including fisheries interactions, illegal harassment, habitat
degradation, disease, intentional killing/harassment, chemical
contaminants, power plant entrainment, vessel strike, harmful algal
blooms, commercial aquaculture, and harassment/disturbance at
rookeries.
As shown in table 99, the maximum annual allowable instances of
take by Level B harassment for pinnipeds ranges from 999 (Eastern stock
of Steller sea lion) to 1,899,749 (U.S. stock of California sea lion),
with 3 stocks below 23,000, 5 stocks above 23,000, and California sea
lion being the only stock over 348,000. Take by Level A harassment is
at or below 12 for four stocks, and above 12 for four stocks. As
described above, given the limited number of potential exposures and
the anticipated effectiveness of the mitigation measures in minimizing
the pressure levels to which any individuals are exposed, these
injuries are unlikely to impact reproduction or survival. No mortality
is anticipated or proposed for authorization for any pinniped stocks
except the U.S. stock of California sea lion, Mexico stock of Guadalupe
fur seal, and California stock of harbor seal. For those three stocks,
the rule also allows for up to 27, 1, and 7 takes by serious injury or
mortality, respectively, over the course of the 7-year rule, the
impacts of which are discussed above in the Serious Injury and
Mortality section. The total take proposed for authorization across all
7 years of the rule is indicated in table 54.
Regarding the potential takes associated with auditory impairment,
as described in the Auditory Injury from Sonar Acoustic Sources and
Explosives and Non-Auditory Injury from Explosives section above, any
takes in the form of TTS are expected to be lower-level, of short
duration (from minutes to, at most, several hours or less than a day),
and mostly not in a frequency band that would be expected to interfere
with pinniped communication or other important auditory cues. Any
associated lost opportunities or capabilities individuals might
experience as a result of TTS would not be at a level or duration that
would be expected to impact reproductive success or survival. For
similar reasons, while auditory injury impacts last longer, the low
anticipated levels of AUD INJ that could be reasonably expected to
result from these activities are unlikely to have any effect on
fitness.
The rule also allows for a limited number of takes by non-auditory
injury (1 to 57) for 7 of the 8 stocks (less than five takes for all
stocks except for the U.S. stock of California sea lion and California
stock of harbor seal). As described above in the Auditory Injury from
Sonar Acoustic Sources and Explosives and Non-Auditory Injury from
Explosives section, given the limited number of potential exposures and
the anticipated effectiveness of the mitigation measures in minimizing
the pressure levels to which any individuals are exposed, these non-
auditory injuries are unlikely to be of a nature or level that would
impact reproduction or survival of these stocks, with the exception of
the U.S. stock of California sea lion and California stock of harbor
seal.
Due to the larger number of California sea lion and California
stock of harbor seal individuals predicted to be exposed annually to
levels associated with non-auditory injury (57 and 7, respectively), it
is more likely that some subset of these individuals could potentially
be injured in a manner that would result in them foregoing reproduction
for a year (up to 10 California sea lions and 1 harbor seal). A year of
foregone reproduction for a male is generally meaningless to population
rates unless the animal ultimately dies. M/SI have been modeled for
this activity separately, and NMFS does not anticipate that these non-
auditory injuries would result in mortality, for young or adults. The
U.S. stock of California sea lion is considered stable. While the
population trend of the California stock of harbor seal is decreasing,
neither of these stocks are considered depleted or strategic, and total
annual mortality is well below PBR for both stocks. Importantly, the
increase in a pupping interval by a year would have far less of an
impact on a population rate than a mortality would and, accordingly,
the number of instances of foregone reproduction predicted here would
not be expected to adversely affect this stock through effects on
annual rates of recruitment or survival.
Regarding the likely severity of any single instance of take by
behavioral disturbance, as described above, the majority of the
predicted exposures are expected to be below 172 dB SPL and last from a
few minutes to a few hours, at most, with associated responses most
likely in the form of moving away from the source, foraging
interruptions, vocalization changes, or disruption of other social
behaviors, lasting from a few minutes to several hours. Pinnipeds are
small-bodied (or small to medium-bodied) income breeders with a fast
pace of life but have a relatively lower energy requirement for their
body size, which may moderate any impact due to foraging disruption.
Further, as described in the Group and Species-Specific Analyses
section above and in the Proposed Mitigation Measures section,
mitigation measures are expected to further reduce the potential
severity of impacts through real-time operational measures that
minimize higher level/longer duration exposures and time/area measures
that reduce impacts in high value habitat. In particular, this proposed
rulemaking includes a Hawaii Island Marine Mammal Mitigation Area and a
Hawaii 4-Islands Marine Mammal Mitigation Area which would reduce
exposure of Hawaiian monk seals to levels of sound that have the
potential to cause injury or behavioral impacts, including within a
portion of Hawaiian monk seal critical habitat.
As described above, in addition to evaluating the anticipated
impacts of the single instances of takes, it is important to understand
the degree to which individual marine mammals may be disturbed
repeatedly across multiple days of the year. Given the number of takes
by harassment as compared to the stock/species abundance alone (see
table 99), and also in consideration of their movement pattern and
whether

[[Page 32332]]

take is concentrated in areas in which animals are known to congregate,
it is unlikely that these individual pinnipeds would be taken on more
than a limited number of days within a year (with the exception of
California sea lion for which some individuals may be taken on a
limited to moderate number of days within a year) and, therefore, the
anticipated behavioral disturbance is not expected to affect
reproduction or survival. However, given the variety of activity types
that contribute to take across separate exercises conducted at
different times and in different areas, and the fact that many result
from transient activities conducted at sea, it is unlikely that
repeated takes would occur either in numbers or clumped across
sequential days in a manner likely to impact foraging success and
energetics or other behaviors such that reproduction or survival of any
individuals is likely to be impacted. Further, many of these stocks are
migratory and apart from the small resident populations, there are no
known foraging areas or other areas within which animals are known to
congregate for important behaviors, and for most stocks, the predicted
takes are not concentrated within a specific region and season.
Given the magnitude and severity of the take by harassment
discussed above and any anticipated habitat impacts, and in
consideration of the required mitigation measures and other information
presented, the Action Proponents' activities are unlikely to result in
impacts on the reproduction or survival of any individuals of pinniped
stocks, with the exception of the three stocks for which takes by M/SI
are predicted and the two stocks for which an increased pupping
interval could potentially occur. Regarding the U.S. stock of
California sea lion and California stock of harbor seal, as described
above, we do not anticipate the relatively limited number of
individuals that might be taken by non-auditory injury in a manner that
results in a year of foregone reproduction to adversely affect the
stock through effects on rates of recruitment or survival, given the
status of the stocks. Regarding the U.S. stock of California sea lion,
Mexico stock of Guadalupe fur seal, and California stock of harbor
seal, as described in the Serious Injury and Mortality section, given
the status of the stocks and in consideration of other ongoing
anthropogenic mortality, the amount of allowed M/SI take proposed here
would not alone, nor in combination with the impacts of the take by
harassment discussed above (which are not expected to impact the
reproduction or survival of any individuals for those stocks), be
expected to adversely affect rates of recruitment and survival. For
these reasons, we have determined that the total take (considering
annual maxima and across 7 years) anticipated and proposed for
authorization would have a negligible impact on all pinniped species
and stocks.

Preliminary Determination

Based on the analysis contained herein of the likely effects of the
specified activities on marine mammals and their habitat, and taking
into consideration the implementation of the proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the specified activity will have a negligible impact
on all affected marine mammal species or stocks.

Unmitigable Adverse Impact Analysis and Determination

There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.

Classification

Endangered Species Act

There are 10 marine mammal species under NMFS jurisdiction that are
listed as endangered or threatened under the ESA with confirmed or
possible occurrence in the HCTT Study Area: blue whale, fin whale, gray
whale, humpback whale, sei whale, sperm whale, killer whale, false
killer whale, Guadalupe fur seal, and Hawaiian monk seal. The humpback
whale (86 FR 21082, April 21, 2021), killer whale (71 FR 69054,
November 29, 2006; revised August 2, 2021 (86 FR 41668)), false killer
whale (83 FR 35062, July 24, 2018), and Hawaiian monk seal (51 FR
16047, April 30, 1986; revised in 1988 (53 FR 18988, May 26, 1988) and
in 2015 (80 FR 50925, August 21, 2015)) have critical habitat
designated under the ESA in the HCTT Study Area.
The Action Proponents will consult with NMFS pursuant to section 7
of the ESA for the HCTT Study Area activities. NMFS will also consult
internally on the issuance of the regulations and three LOAs under
section 101(a)(5)(A) of the MMPA.

National Marine Sanctuaries Act

The Action Proponents and NMFS will work with NOAA's Office of
National Marine Sanctuaries to fulfill our responsibilities under the
National Marine Sanctuaries Act as warranted and will complete any NMSA
requirements prior to a determination on the issuance of the final rule
and LOAs.

National Environmental Policy Act

To comply with the National Environmental Policy Act of 1969 (NEPA)
(42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review its proposed actions with respect to potential impacts
on the human environment. Accordingly, NMFS plans to adopt the 2024
HCTT Draft EIS/OEIS for the HCTT Study Area, provided our independent
evaluation of the document finds that it includes adequate information
analyzing the effects on the human environment of issuing regulations
and LOAs under the MMPA. NMFS is a cooperating agency on the 2024 HCTT
Draft EIS/OEIS and has worked extensively with the Navy in developing
the document. The 2024 HCTT Draft EIS/OEIS was made available for
public comment at: https://www.nepa.navy.mil/hctteis/, which also
provides additional information about the NEPA process, from December
13, 2024, to February 11, 2025. We will review all comments prior to
concluding our NEPA process and making a final decision on the MMPA
rulemaking and request for LOAs.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
MMPA rule and request for LOAs.

Executive Order 12866

The Office of Management and Budget has determined that this
proposed rule is not significant for purposes of Executive Order 12866.

Executive Order 14192

This proposed rule is not an Executive Order 14192 regulatory
action because this rule is not significant under Executive Order
12866.

Regulatory Flexibility Act

Pursuant to the Regulatory Flexibility Act (RFA), the Chief Counsel
for Regulation of the Department of Commerce has certified to the Chief
Counsel for Advocacy of the Small Business Administration that this
proposed rule, if adopted, would not have a significant economic impact
on a substantial number of small entities.

[[Page 32333]]

The Regulatory Flexibility Act (RFA) requires Federal agencies to
prepare an analysis of a rule's impact on small entities whenever the
agency is required to publish a notice of proposed rulemaking. However,
a Federal agency may certify, pursuant to 5 U.S.C. 605(b), that the
action will not have a significant economic impact on a substantial
number of small entities. The Action Proponents are the only entities
that would be affected by this proposed rulemaking, and the Action
Proponents are not a small governmental jurisdiction, small
organization, or small business, as defined by the RFA. Any
requirements imposed by an LOA issued pursuant to these regulations,
and any monitoring or reporting requirements imposed by these
regulations, would be applicable only to the Action Proponents. NMFS
does not expect the issuance of these regulations or the associated
LOAs to result in any impacts to small entities pursuant to the RFA.
Because this action, if adopted, would directly affect only the Action
Proponents and not any small entities, NMFS concludes that the action
would not result in a significant economic impact on a substantial
number of small entities. As a result, an initial regulatory
flexibility analysis is not required and none has been prepared.

List of Subjects in 50 CFR Part 218

Administrative practice and procedure, Endangered and threatened
species, Fish, Fisheries, Marine mammals, Penalties, Reporting and
recordkeeping requirements, Transportation, Wildlife.

Dated: July 10, 2025.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.

For reasons set forth in the preamble, NMFS proposes to amend 50
CFR part 218 as follows:

PART 218--REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE
MAMMALS

0
1. The authority citation for part 218 continues to read as follows:

Authority: 16 U.S.C. 1361 et seq.

0
2. Revise subpart H of part 218 to read as follows:
Subpart H--Taking and Importing Marine Mammals; Military Readiness
Activities in the Hawaii-California Training and Testing Study Area
Sec.
218.70 Specified activity and geographical region.
218.71 Effective dates.
218.72 Permissible methods of taking.
218.73 Prohibitions.
218.74 Mitigation requirements.
218.75 Requirements for monitoring and reporting.
218.76 Letters of Authorization.
218.77 Modifications of Letters of Authorization.
218.78-218.79 [Reserved]

Subpart H--Taking and Importing Marine Mammals; Military Readiness
Activities in the Hawaii-California Training and Testing Study Area

Sec. 218.70 Specified activity and geographical region.

(a) Regulations in this subpart apply only to the U.S. Navy
(including the U.S. Marine Corps; Navy), U.S. Coast Guard (Coast
Guard), and U.S. Army (collectively referred to as the ``Action
Proponents'') for the taking of marine mammals that occurs in the area
described in paragraph (b) of this section and that occurs incidental
to the activities listed in paragraph (c) of this section. Requirements
imposed on the Action Proponents must be implemented by those persons
they authorize or funds to conduct activities on their behalf.
(b) The taking of marine mammals by the Action Proponents under
this subpart may be authorized in Letters of Authorization (LOAs) only
if it occurs within the Hawaii-California Training and Testing (HCTT)
Study Area. The HCTT Study Area includes areas in the north-central
Pacific Ocean, from California west to Hawaii and the International
Date Line, and including the Hawaii Range Complex (HRC), Southern
California (SOCAL) Range Complex, Point Mugu Sea Range (PMSR), Silver
Strand Training Complex, and the Northern California (NOCAL) Range
Complex. Figure 1 to this paragraph (b) shows the location of the HCTT
Study Area.
(c) The taking of marine mammals by the Action Proponents is only
authorized if it occurs incidental to the Action Proponents conducting
military readiness activities, including the following:
(1) Amphibious warfare;
(2) Anti-submarine warfare;
(3) Expeditionary warfare;
(4) Mine warfare;
(5) Surface warfare;
(6) Vessel evaluation;
(7) Unmanned systems;
(8) Acoustic and oceanographic science and technology;
(9) Vessel movement;
(10) Land-based launches; and
(11) Other training and testing activities.
BILLING CODE 3510-22-P

Figure 1 to Paragraph (b)--HCTT Study Area

[[Page 32334]]

[GRAPHIC] [TIFF OMITTED] TP16JY25.002

BILLING CODE 3510-22-C

Sec. 218.71 Effective dates.

Regulations in this subpart are effective from December 21, 2025,
through December 20, 2032.

Sec. 218.72 Permissible methods of taking.

(a) Under LOAs issued pursuant to Sec. Sec. 216.106 of this
chapter and this subpart, the Holder of the LOA (hereinafter ``Action
Proponent'') may incidentally, but not intentionally, take marine
mammals within the area described in Sec. 218.70(b) by Level A
harassment and Level B harassment associated with the use of active
sonar and other acoustic sources and explosives, as well as serious
injury or mortality associated with vessel strikes and explosives,
provided the activity is in compliance with all terms, conditions, and
requirements of this subpart and the applicable LOAs.
(b) The incidental take of marine mammals by the activities listed
in Sec. 218.70(c) is limited to the following species:

Table 1 to Paragraph (b)
------------------------------------------------------------------------
Species Stock
------------------------------------------------------------------------
Gray whale............................. Eastern North Pacific.
Gray whale............................. Western North Pacific.
Blue whale............................. Central North Pacific.
Blue whale............................. Eastern North Pacific.
Bryde's whale.......................... Eastern Tropical Pacific.
Bryde's whale.......................... Hawaii.
Fin whale.............................. Hawaii.
Fin whale.............................. California/Oregon/Washington.
Humpback whale......................... Central America/Southern Mexico-
California-Oregon-Washington.
Humpback whale......................... Mainland Mexico-California-
Oregon-Washington.

[[Page 32335]]

Humpback whale......................... Hawaii.
Minke whale............................ Hawaii.
Minke whale............................ California/Oregon/Washington.
Sei whale.............................. Hawaii.
Sei whale.............................. Eastern North Pacific.
Sperm whale............................ Hawaii.
Sperm whale............................ California/Oregon/Washington.
Dwarf sperm whale...................... Hawaii.
Dwarf sperm whale...................... California/Oregon/Washington.
Pygmy sperm whale...................... Hawaii.
Pygmy sperm whale...................... California/Oregon/Washington.
Baird's beaked whale................... California/Oregon/Washington.
Blainville's beaked whale.............. Hawaii.
Goose-beaked whale..................... Hawaii.
Goose-beaked whale..................... California/Oregon/Washington.
Longman's beaked whale................. Hawaii.
Mesoplodont beaked whale............... California/Oregon/Washington.
False killer whale..................... Main Hawaiian Islands Insular.
False killer whale..................... Northwest Hawaiian Islands.
False killer whale..................... Hawaii Pelagic.
False killer whale..................... Baja California Peninsula
Mexico population.
Killer whale........................... Hawaii.
Killer whale........................... Eastern North Pacific Offshore.
Killer whale........................... West Coast Transient.
Melon-headed whale..................... Hawaiian Islands.
Melon-headed whale..................... Kohala Resident (Hawaii).
Pygmy killer whale..................... Hawaii.
Pygmy killer whale..................... California-Baja California
Peninsula Mexico population.
Short-finned pilot whale............... Hawaii.
Short-finned pilot whale............... California/Oregon/Washington.
Bottlenose dolphin..................... Maui Nui.
Bottlenose dolphin..................... Hawaii Island.
Bottlenose dolphin..................... Hawaii Pelagic.
Bottlenose dolphin..................... Kaua[revaps]i/Ni[revaps]ihau.
Bottlenose dolphin..................... O[revaps]ahu.
Bottlenose dolphin..................... California Coastal.
Bottlenose dolphin..................... California/Oregon/Washington
Offshore.
Fraser's dolphin....................... Hawaii.
Long-beaked common dolphin............. California.
Northern right whale dolphin........... California/Oregon/Washington.
Pacific white-sided dolphin............ California/Oregon/Washington.
Pantropical spotted dolphin............ Maui Nui.
Pantropical spotted dolphin............ Hawaii Island.
Pantropical spotted dolphin............ Hawaii Pelagic.
Pantropical spotted dolphin............ O[revaps]ahu.
Pantropical spotted dolphin............ Baja California Peninsula
Mexico population.
Risso's dolphin........................ Hawaii.
Risso's dolphin........................ California/Oregon/Washington.
Rough-toothed dolphin.................. Hawaii.
Short-beaked common dolphin............ California/Oregon/Washington.
Spinner dolphin........................ Hawaii Pelagic.
Spinner dolphin........................ Hawaii Island.
Spinner dolphin........................ Kaua[revaps]i/Ni[revaps]ihau.
Spinner dolphin........................ O[revaps]ahu/4 Islands Region.
Striped dolphin........................ Hawaii Pelagic.
Striped dolphin........................ California/Oregon/Washington.
Dall's porpoise........................ California/Oregon/Washington.
Harbor porpoise........................ Monterey Bay.
Harbor porpoise........................ Morro Bay.
Harbor porpoise........................ Northern California/Southern
Oregon.
Harbor porpoise........................ San Francisco/Russian River.
California sea lion.................... U.S.
Guadalupe fur seal..................... Mexico.
Northern fur seal...................... Eastern Pacific.
Northern fur seal...................... California.
Steller sea lion....................... Eastern.
Harbor seal............................ California.
Hawaiian monk seal..................... Hawaii.
Northern elephant seal................. California Breeding.
------------------------------------------------------------------------

[[Page 32336]]

Sec. 218.73 Prohibitions.

(a) Except incidental take described in Sec. 218.72 and authorized
by a LOA issued under this subpart, it shall be unlawful for any person
to do the following in connection with the activities described in this
subpart:
(1) Violate, or fail to comply with, the terms, conditions, and
requirements of this subpart or a LOA issued under Sec. Sec. 216.106
and this subpart;
(2) Take any marine mammal not specified in Sec. 218.72(b);
(3) Take any marine mammal specified in Sec. 218.72(b) in any
manner other than as specified in the LOAs; or
(4) Take a marine mammal specified in Sec. 218.72(b) after NMFS
determines such taking results in more than a negligible impact on the
species or stock of such marine mammal.
(b) [Reserved]

Sec. 218.74 Mitigation requirements.

(a) When conducting the activities identified in Sec. 218.70(c),
the mitigation measures contained in this section and any LOA issued
under this subpart must be implemented by Action Proponent personnel or
contractors who are trained according to the requirements in the LOA.
If Action Proponent contractors are serving in a role similar to Action
Proponent personnel, Action Proponent contractors must follow the
mitigation applicable to Action Proponent personnel. These mitigation
measures include, but are not limited to:
(1) Activity-based mitigation. Activity-based mitigation is
mitigation that the Action Proponents must implement whenever and
wherever an applicable military readiness activity takes place within
the HCTT Study Area. The Action Proponents must implement the
mitigation described in paragraphs (a)(1)(i) through (a)(1)(xxii) of
this section, except as provided in paragraph (a)(1)(xxiii).
(i) Active acoustic sources with power down and shut down
capabilities. For active acoustic sources with power down and shutdown
capabilities (low-frequency active sonar >=200 dB, mid-frequency active
sonar sources that are hull mounted on a surface ship (including
surfaced submarines), and broadband and other active acoustic sources
>200 dB):
(A) Mitigation zones and requirements. During use of active
acoustic sources with power down and shutdown capabilities, the
following mitigation zone requirements apply:
(1) At 1,000 yd (914.4 m) from a marine mammal, Action Proponent
personnel must power down active acoustic sources by 6 decibels (dB)
total.
(2) At 500 yd (457.2 m) from a marine mammal, Action Proponent
personnel must power down active acoustic sources by an additional 4 dB
(10 dB total).
(3) At 200 yd (182.9 m) from a marine mammal, Action Proponent
personnel must shut down active acoustic sources.
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in or on one of the following: aircraft; pierside,
moored, or anchored vessel; underway vessel with space/crew
restrictions (including small boats); or underway vessel already
participating in the event that is escorting (and has positive control
over sources used, deployed, or towed by) an unmanned platform.
(2) Two Lookouts on an underway vessel without space or crew
restrictions.
(3) Lookouts must use information from passive acoustic detections
to inform visual observations when passive acoustic devices are already
being used in the event.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of using active acoustic sources (e.g.,
while maneuvering on station).
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during use of active acoustic
sources.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing or powering up active sonar transmission). The
wait period for this activity is 30 minutes for activities conducted
from vessels and for activities conducted by aircraft that are not fuel
constrained and 10 minutes for activities involving aircraft that are
fuel constrained (e.g., rotary-wing aircraft, fighter aircraft).
(ii) Active acoustic sources with shut down capabilities only (no
power down capability). For active acoustic sources with shut down
capabilities only (no power down capability) (low-frequency active
sonar <200 dB, mid-frequency active sonar sources that are not hull
mounted on a surface ship (e.g., dipping sonar, towed arrays), high-
frequency active sonar, air guns, and broadband and other active
acoustic sources <200 dB):
(A) Mitigation zones and requirements. During use of active
acoustic sources with shut down capabilities only, the following
mitigation zone requirements apply:
(1) At 200 yd (182.9 m) from a marine mammal, Action Proponent
personnel must shut down active acoustic sources.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in or on one of the following: aircraft; pierside,
moored, or anchored vessel; underway vessel with space/crew
restrictions (including small boats); or underway vessel already
participating in the event that is escorting (and has positive control
over sources used, deployed, or towed by) an unmanned platform.
(2) Two Lookouts on an underway vessel without space or crew
restrictions.
(3) Lookouts must use information from passive acoustic detections
to inform visual observations when passive acoustic devices are already
being used in the event.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of using active acoustic sources (e.g.,
while maneuvering on station).
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during use of active acoustic
sources.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing or powering up active sonar transmission). The
wait period for this activity is 30 minutes for activities conducted
from vessels and for activities conducted by aircraft that are not fuel
constrained and 10 minutes for activities involving aircraft that are
fuel constrained (e.g., rotary-wing aircraft, fighter aircraft).
(iii) Pile driving and extraction. For pile driving and extraction:
(A) Mitigation zones and requirements. During vibratory and impact
pile driving and extraction, the following mitigation zone requirements
apply:

[[Page 32337]]

(1) Action Proponent personnel must cease pile driving or
extraction if a marine mammal is sighted within 5 yd (4.6 m) of a pile
being driven or extracted.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in or on one of the following: shore, pier, or
small boat.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals and floating vegetation for 15 minutes prior to the
initial start of pile driving or pile extraction.
(2) Action Proponent personnel must observe the mitigation zone for
marine mammals during pile driving or extraction.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing vibratory or impact pile driving or extraction).
The wait period for this activity is 15 minutes.
(iv) Weapons firing noise. For weapons firing noise:
(A) Mitigation zones and requirements. During explosive and non-
explosive large-caliber (57 mm and larger) gunnery firing noise
(surface-to-surface and surface-to-air), the following mitigation zone
requirements apply:
(1) Action Proponent personnel must cease weapons firing if a
marine mammal is sighted within 30 degrees on either side of the firing
line out to 70 yd (64 m) from the gun muzzle (cease fire).
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on a vessel.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals and floating vegetation immediately prior to the initial
start of large-caliber gun firing (e.g., during target deployment).
(2) Action Proponent personnel must observe the mitigation zone for
marine mammals during large-caliber gun firing.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing explosive and non-explosive large-caliber gunnery
firing noise (surface-to-surface and surface-to-air)). The wait period
for this activity is 30 minutes.
(v) Explosive bombs. For explosive bombs:
(A) Mitigation zones and requirements. During the use of explosive
bombs of any net explosive weight (NEW), the following mitigation zone
requirements apply:
(1) Action Proponent personnel must cease explosive bomb use if a
marine mammal is sighted within 2,500 yd (2,286 m) from the intended
target.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in an aircraft.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of bomb delivery (e.g., when arriving on
station).
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during bomb delivery. If a marine
mammal is visibly injured or killed as a result of detonation,
explosives use in the event must be suspended immediately.
(3) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals. If any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of explosive bombs of any NEW). The wait
period for this activity is 10 minutes.
(vi) Explosive gunnery. For explosive gunnery:
(A) Mitigation zones and requirements. During air-to-surface
medium-caliber (larger than 50 caliber and less than 57 mm), surface-
to-surface medium-caliber, and surface-to-surface large-caliber
explosive gunnery, the following mitigation zone requirements apply:
(1) Action Proponent personnel must cease air-to-surface medium-
caliber use if a marine mammal is sighted within 200 yd (182.9 m) of
the intended impact location.
(2) Action Proponent personnel must cease surface-to-surface
medium-caliber use if a marine mammal is sighted within 600 yd (548.6
m) of the intended impact location.
(3) Action Proponent personnel must cease surface-to-surface large-
caliber use if a marine mammal is sighted within 1,000 yd (914.4 m) of
the intended impact location.
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on a vessel or in an aircraft.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of gun firing (e.g., while maneuvering on
station).
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during gunnery fire. If a marine
mammal is visibly injured or killed as a result of detonation,
explosives use in the event must be suspended immediately.
(3) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals. If any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing air-to-surface medium-caliber, surface-to-surface
medium-caliber, surface-to-surface large-caliber explosive gunnery).
The wait period for this activity is 30 minutes for activities
conducted from vessels and for activities conducted by aircraft that
are not fuel constrained and 10 minutes for activities involving
aircraft that are fuel constrained (e.g., rotary-wing aircraft, fighter
aircraft).
(vii) Explosive underwater demolition multiple charge--mat weave
and obstacle loading. For explosive underwater demolition multiple

[[Page 32338]]

charge--mat weave and obstacle loading:
(A) Mitigation zones and requirements. During the use of explosive
underwater demolition multiple charge--mat weave and obstacle loading
of any NEW, the following mitigation zone requirements apply:
(1) Action Proponent personnel must cease explosive underwater
demolition multiple charge--mat weave and obstacle loading if a marine
mammal is sighted within 700 yd (640 m) of the detonation site.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) Two Lookouts, one on a small boat and one on shore from an
elevated platform.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) The Lookout positioned on a small boat must observe the
mitigation zone for marine mammals and floating vegetation for 30
minutes prior to the first detonation.
(2) The Lookout positioned on shore must use binoculars to observe
for marine mammals for 10 minutes prior to the first detonation.
(3) Action Proponent personnel must observe the mitigation zone for
marine mammals during detonations. If a marine mammal is visibly
injured or killed as a result of detonation, explosives use in the
event must be suspended immediately.
(4) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals. If any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of explosive underwater demolition multiple
charge--mat weave and obstacle loading of any NEW). The wait period for
this activity is 10 minutes (determined by the Lookout on shore).
(viii) Explosive mine countermeasure and neutralization (no
divers). For explosive mine countermeasure and neutralization (no
divers):
(A) Mitigation zones and requirements. During explosive mine
countermeasure and neutralization using 0.1-5 pound (lb) (0.05-2.3
kilogram (kg)) NEW and >5 lb (2.3 kg) NEW, the following mitigation
zone requirements apply:
(1) Action Proponent personnel must cease 0.1-5 lb (0.05-2.3 kg)
NEW use if a marine mammal is sighted within 600 yd (548.6 m) from the
detonation site.
(2) Action Proponent personnel must cease >5 lb (2.3 kg) NEW use if
a marine mammal is sighted within 2,100 yd (1,920.2 m) from the
detonation site.
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on a vessel or in an aircraft during 0.1-5 lb
(0.05-2.3 kg) NEW use.
(2) Two Lookouts, one on a small boat and one in an aircraft during
>5 lb (2.3 kg) NEW use.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of detonations (e.g., while maneuvering on
station; typically, 10 or 30 minutes depending on fuel constraints).
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals, concentrations of seabirds, and
individual foraging seabirds (in the water and not on shore) during
detonations or fuse initiation. If a marine mammal is visibly injured
or killed as a result of detonation, explosives use in the event must
be suspended immediately.
(3) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for 10 or 30 minutes (depending on
fuel constraints) for injured or dead marine mammals. If any injured or
dead marine mammals are observed, Action Proponent personnel must
follow established incident reporting procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing explosive mine countermeasure and neutralization
using 0.1-5 pound (lb) (0.05-2.3 kilogram (kg)) NEW and >5 lb (2.3 kg)
NEW). The wait period for this activity is 30 minutes for activities
conducted from vessels and for activities conducted by aircraft that
are not fuel constrained and 10 minutes for activities involving
aircraft that are fuel constrained (e.g., rotary-wing aircraft, fighter
aircraft).
(ix) Explosive mine neutralization (with divers). For explosive
mine neutralization (with divers):
(A) Mitigation zones and requirements. During explosive mine
neutralization (with divers) using 0.1-20 lb (0.05-9.1 kg) NEW
(positive control), 0.1-29 lb (0.05-13.2 kg) NEW (time-delay), and >20-
60 lb (9.1-27.2 kg) NEW (positive control), the following mitigation
zone requirements apply:
(1) Action Proponent personnel must cease 0.1-20 lb (0.05-9.1 kg)
NEW (positive control) use if a marine mammal is sighted within 500 yd
(457.2 m) of the detonation site (cease fire).
(2) Action Proponent personnel must cease 0.1-29 lb (0.05-13.2 kg)
NEW (time-delay) and >20-60 lb (9.1-27.2 kg) NEW (positive control) use
if a marine mammal is sighted within 1,000 yd (914.4 m) of the
detonation site (cease fire).
(B) Lookout requirements. The following Lookout requirements apply:
(1) Lookouts in two small boats (one Lookout per boat), or one
small boat and one rotary-wing aircraft (with one Lookout each), and
one Lookout on shore for shallow-water events during 0.1-20 lb (0.05-
9.1 kg) NEW (positive control) use.
(2) Four Lookouts in two small boats (two Lookouts per boat) and
one additional Lookout in an aircraft if used in the event during 0.1-
29 lb (0.05-13.2 kg) NEW (time-delay) and >20-60 lb (9.1-27.2 kg) NEW
(positive control) use.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Time-delay devices must be set not to exceed 10 minutes.
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of detonations or fuse initiation for
positive control events (e.g., while maneuvering on station) or for 30
minutes prior for time-delay events.
(3) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals, concentrations of seabirds, and
individual foraging seabirds (in the water and not on shore) during
detonations or fuse initiation. If a marine mammal is visibly injured
or killed as a result of detonation, explosives use in the event must
be suspended immediately.

[[Page 32339]]

(4) When practical based on mission, safety, and environmental
conditions:
(i) Boats must observe from the mitigation zone radius mid-point.
(ii) When two boats are used, boats must observe from opposite
sides of the mine location.
(iii) Platforms must travel a circular pattern around the mine
location.
(iv) Boats must have one Lookout observe inward toward the mine
location and one Lookout observe outward toward the mitigation zone
perimeter.
(v) Divers must be part of the Lookout Team.
(5) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for 30 minutes for injured or dead
marine mammals. If any injured or dead marine mammals are observed,
Action Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing explosive mine neutralization (with divers) using
0.1-20 lb (0.05-9.1 kg) NEW (positive control), 0.1-29 lb (0.05-13.2
kg) NEW (time-delay), and >20-60 lb (9.1-27.2 kg) NEW (positive
control)). The wait period for this activity is 30 minutes for
activities conducted from vessels and for activities conducted by
aircraft that are not fuel constrained and 10 minutes for activities
involving aircraft that are fuel constrained (e.g., rotary-wing
aircraft, fighter aircraft).
(x) Explosive missiles and rockets. For explosive missiles and
rockets:
(A) Mitigation zones and requirements. During the use of explosive
missiles and rockets using 0.6-20 lb (0.3-9.1 kg) NEW (air-to-surface)
and >20-500 lb (9.1-226.8 kg) NEW (air-to-surface), the following
mitigation zone requirements apply:
(1) Action Proponent personnel must cease 0.6-20 lb (0.3-9.1 kg)
NEW (air-to-surface) use if a marine mammal is sighted within 900 yd
(823 m) of the intended impact location (cease fire).
(2) Action Proponent personnel must cease >20-500 lb (9.1-226.8 kg)
NEW (air-to-surface) use if a marine mammal is sighted within 2,000 yd
(1,828.8 m) of the intended impact location (cease fire).
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in an aircraft.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals and floating vegetation immediately
prior to the initial start of missile or rocket delivery (e.g., during
a fly-over of the mitigation zone).
(2) Action Proponent personnel must observe the applicable
mitigation zone for marine mammals during missile or rocket delivery.
If a marine mammal is visibly injured or killed as a result of
detonation, explosives use in the event must be suspended immediately.
(3) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals. If any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of explosive missiles and rockets using 0.6-20
lb (0.3-9.1 kg) NEW (air-to-surface) and >20-500 lb (9.1-226.8 kg) NEW
(air-to-surface)). The wait period for this activity is 30 minutes for
activities conducted by aircraft that are not fuel constrained and 10
minutes for activities involving aircraft that are fuel constrained
(e.g., rotary-wing aircraft, fighter aircraft).
(xi) Explosive sonobuoys and research-based sub-surface explosives.
For explosive sonobuoys and research-based sub-surface explosives:
(A) Mitigation zones and requirements. During the use of explosive
sonobuoys and research-based sub-surface explosives using any NEW of
sonobuoys and 0.1-5 lb (0.05-2.3 kg) NEW for other types of sub-surface
explosives used in research applications, the following mitigation zone
requirements apply:
(1) Action Proponent personnel must cease use of explosive
sonobuoys and research-based sub-surface explosives using any NEW of
sonobuoys and 0.1-5 lb (0.05-2.3 kg) NEW for other types of sub-surface
explosives used in research applications if a marine mammal is sighted
within 600 yd (548.6 m) of the device or detonation sites (cease fire).
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on a small boat or in an aircraft.
(2) Conduct passive acoustic monitoring for marine mammals; use
information from detections to assist visual observations.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals and floating vegetation immediately prior to the initial
start of detonations (e.g., during sonobuoy deployment, which typically
lasts 20-30 minutes).
(2) Action Proponent personnel must observe the mitigation zone for
marine mammals during detonations. If a marine mammal is visibly
injured or killed as a result of detonation, explosives use in the
event must be suspended immediately.
(3) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals. If any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of explosive sonobuoys and research-based sub-
surface explosives using any NEW of sonobuoys and 0.1-5 lb (0.05-2.3
kg) NEW for other types of sub-surface explosives used in research
applications). The wait period for this activity is 30 minutes for
activities conducted from vessels and for activities conducted by
aircraft that are not fuel constrained and 10 minutes for activities
involving aircraft that are fuel constrained (e.g., rotary-wing
aircraft, fighter aircraft).
(xii) Explosive torpedoes. For explosive torpedoes:
(A) Mitigation zones and requirements. During the use of explosive
torpedoes of any NEW, the following mitigation zone requirements apply:
(1) Action Proponent personnel must cease use of explosive
torpedoes of any NEW if a marine mammal is sighted within 2,100 yd
(1,920.2 m) of the intended impact location.
(2) [Reserved]

[[Page 32340]]

(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in an aircraft.
(2) Conduct passive acoustic monitoring for marine mammals; use
information from detections to assist visual observations.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals, floating vegetation, and jellyfish aggregations
immediately prior to the initial start of detonations (e.g., during
target deployment).
(2) Action Proponent personnel must observe the mitigation zone for
marine mammals and jellyfish aggregations during torpedo launches. If a
marine mammal is visibly injured or killed as a result of detonation,
explosives use in the event must be suspended immediately.
(3) After the event, when practical, Action Proponent personnel
must observe the detonation vicinity for injured or dead marine
mammals. If any injured or dead marine mammals are observed, Action
Proponent personnel must follow established incident reporting
procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of explosive torpedoes of any NEW). The wait
period for this activity is 30 minutes for activities conducted from
vessels and for activities conducted by aircraft that are not fuel
constrained and 10 minutes for activities involving aircraft that are
fuel constrained (e.g., rotary-wing aircraft, fighter aircraft).
(xiii) Ship shock trials. For ship shock trials:
(A) Mitigation zones and requirements. During ship shock trials
using any NEW, the following mitigation zone requirements apply:
(1) Action Proponent personnel must cease ship shock trials of any
NEW if a marine mammal is sighted within 3.5 nmi (6.5 km) of the target
ship hull (cease fire).
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) On the day of the event, 10 observers (Lookouts and third-party
observers combined), spread between aircraft or multiple vessels as
specified in the event-specific mitigation plan.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must develop a detailed, event-
specific monitoring and mitigation plan in the year prior to the event
and provide it to NMFS for review.
(2) Beginning at first light on days of detonation, until the
moment of detonation (as allowed by safety measures) Action Proponent
personnel must observe the mitigation zone for marine mammals, floating
vegetation, jellyfish aggregations, large schools of fish, and flocks
of seabirds. If a marine mammal is visibly injured or killed as a
result of detonation, explosives use in the event must be suspended
immediately.
(3) If any injured or dead marine mammals are observed after an
individual detonation, Action Proponent personnel must follow
established incident reporting procedures and halt any remaining
detonations until Action Proponent personnel can consult with NMFS and
review or adapt the event-specific mitigation plan, if necessary.
(4) During the 2 days following the event (minimum) and up to 7
days following the event (maximum), and as specified in the event-
specific mitigation plan, Action Proponent personnel must observe the
detonation vicinity for injured or dead marine mammals.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing ship shock trials). The wait period for this
activity is 30 minutes.
(xiv) Sinking Exercises. For Sinking Exercises (SINKEX):
(A) Mitigation zones and requirements. During SINKEX using any NEW,
the following mitigation zone requirements apply:
(1) Action Proponent personnel must cease SINKEX of any NEW if a
marine mammal is sighted within 2.5 nmi (4.6 km) of the target ship
hull (cease fire).
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) Two Lookouts, one on a vessel and one in an aircraft.
(2) Conduct passive acoustic monitoring for marine mammals; use
information from detections to assist visual observations.
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) During aerial observations for 90 minutes prior to the initial
start of weapon firing, Action Proponent personnel must observe the
mitigation zone for marine mammals, floating vegetation, and jellyfish
aggregations.
(2) From the vessel during weapon firing, and from the aircraft and
vessel immediately after planned or unplanned breaks in weapon firing
of more than 2 hours, Action Proponent personnel must observe the
mitigation zone for marine mammals. If a marine mammal is visibly
injured or killed as a result of detonation, explosives use in the
event must be suspended immediately.
(3) Action Proponent personnel must observe the detonation vicinity
for injured or dead marine mammals for 2 hours after sinking the vessel
or until sunset, whichever comes first. If any injured or dead marine
mammals are observed, Action Proponent personnel must follow
established incident reporting procedures.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing SINKEX). The wait period for this activity is 30
minutes.
(xv) Non-explosive aerial-deployed mines and bombs. For non-
explosive aerial-deployed mines and bombs:
(A) Mitigation zones and requirements. During the use of non-
explosive aerial-deployed mines and non-explosive bombs, the following
mitigation zone requirements apply:
(1) Action Proponent personnel must cease using non-explosive
aerial-deployed mines and non-explosive bombs if a marine mammal is
sighted within 1,000 yd (914.4 m) of the intended target (cease fire).
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in an aircraft.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals and floating vegetation immediately prior to the initial
start of mine or bomb delivery (e.g., when arriving on station).

[[Page 32341]]

(2) Action Proponent personnel must observe the mitigation zone for
marine mammals during mine or bomb delivery. If a marine mammal is
visibly injured or killed as a result of detonation, explosives use in
the event must be suspended immediately.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of non-explosive aerial-deployed mines and
non-explosive bombs). The wait period for this activity is 10 minutes.
(xvi) Non-explosive gunnery. For non-explosive gunnery:
(A) Mitigation zones and requirements. During the use of non-
explosive surface-to-surface large-caliber ordnance, non-explosive
surface-to-surface and air-to-surface medium-caliber ordnance, and non-
explosive surface-to-surface and air-to-surface small-caliber ordnance,
the following mitigation zone requirements apply:
(1) Action Proponent personnel must cease non-explosive surface-to-
surface large-caliber ordnance, non-explosive surface-to-surface and
air-to-surface medium-caliber ordnance, and non-explosive surface-to-
surface and air-to-surface small-caliber ordnance use if a marine
mammal is sighted within 200 yd (182.9 m) of the intended impact
location (cease fire).
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on a vessel or in an aircraft.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals and floating vegetation immediately prior to the start
of gun firing (e.g., while maneuvering on station).
(2) Action Proponent personnel must observe the mitigation zone for
marine mammals during gunnery firing.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of non-explosive surface-to-surface large-
caliber ordnance, non-explosive surface-to-surface and air-to-surface
medium-caliber ordnance, and non-explosive surface-to-surface and air-
to-surface small-caliber ordnance). The wait period for this activity
is 30 minutes for activities conducted from vessels and for activities
conducted by aircraft that are not fuel constrained and 10 minutes for
activities involving aircraft that are fuel constrained (e.g., rotary-
wing aircraft, fighter aircraft).
(xvii) Non-explosive missiles and rockets. For non-explosive
missiles and rockets:
(A) Mitigation zones and requirements. During the use of non-
explosive missiles and rockets (air-to-surface), the following
mitigation zone requirements apply:
(1) Action Proponent personnel must cease non-explosive missile and
rocket (air-to-surface) use if a marine mammal is sighted within 900 yd
(823 m) of the intended impact location.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout in an aircraft.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals and floating vegetation immediately prior to the start
of missile or rocket delivery (e.g., during a fly-over of the
mitigation zone).
(2) Action Proponent personnel must observe the mitigation zone for
marine mammals during missile or rocket delivery.
(D) Commencement or recommencement conditions. Action Proponent
personnel must ensure one of the commencement or recommencement
conditions in Sec. 218.74(a)(1)(xxii) is met prior to the initial
start of the activity (by delaying the start) or during the activity
(by not recommencing use of non-explosive missiles and rockets (air-to-
surface)). The wait period for this activity is 30 minutes for
activities conducted by aircraft that are not fuel constrained and 10
minutes for activities involving aircraft that are fuel constrained
(e.g., rotary-wing aircraft, fighter aircraft).
(xviii) Manned surface vessels. For manned surface vessels:
(A) Mitigation zones and requirements. During the use of manned
surface vessels, including surfaced submarines, the following
mitigation zone requirements apply:
(1) Underway manned surface vessels must maneuver themselves (which
may include reducing speed) to maintain the following distances as
mission and circumstances allow:
(i) 500 yd (457.2 m) from whales.
(ii) 200 yd (182.9 m) from other marine mammals.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One or more Lookouts on manned underway surface vessels in
accordance with the most recent navigation safety instruction.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals immediately prior to manned surface vessels getting
underway and while underway.
(2) [Reserved]
(xix) Unmanned vehicles. For unmanned vehicles:
(A) Mitigation zones and requirements. During the use of unmanned
surface vehicles and unmanned underwater vehicles already being
escorted (and operated under positive control) by a manned surface
support vessel, the following mitigation zone requirements apply:
(1) A surface support vessel that is already participating in the
event, and has positive control over the unmanned vehicle, must
maneuver the unmanned vehicle (which may include reducing its speed) to
ensure it maintains the following distances as mission and
circumstances allow:
(i) 500 yd (457.2 m) from whales.
(ii) 200 yd (182.9 m) from other marine mammals.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on a surface support vessel that is already
participating in the event, and has positive control over the unmanned
vehicle.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals immediately prior to unmanned vehicles getting underway
and while underway.
(2) [Reserved]
(xx) Towed in-water devices. For towed in-water devices:
(A) Mitigation zones and requirements. During the use of in-water
devices towed by an aircraft, a manned surface vessel, or an Unmanned
Surface Vehicle or Unmanned Underwater

[[Page 32342]]

Vehicle already being escorted (and operated under positive control) by
a manned surface vessel, the following mitigation zone requirements
apply:
(1) Manned towing platforms, or surface support vessels already
participating in the event that have positive control over an unmanned
vehicle that is towing an in-water device, must maneuver itself or the
unmanned vehicle (which may include reducing speed) to ensure towed in-
water devices maintain the following distances as mission and
circumstances allow:
(i) 250 yd (228.6 m) from marine mammals.
(ii) [Reserved]
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on the manned towing vessel or aircraft, or on a
surface support vessel that is already participating in the event and
has positive control over an unmanned vehicle that is towing an in-
water device.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals immediately prior to and while in-water devices are
being towed.
(2) [Reserved]
(xxi) Net deployment. For net deployment:
(A) Mitigation zones and requirements. During net deployment for
testing of an Unmanned Underwater Vehicle, the following mitigation
zone requirements apply:
(1) If a marine mammal is sighted within 500 yd (457.2 m) of the
deployment location, the support vessel will:
(i) Delay deployment of nets until the mitigation zone has been
clear for 15 minutes.
(ii) Recover nets if they are deployed.
(2) [Reserved]
(B) Lookout requirements. The following Lookout requirements apply:
(1) One Lookout on the support vessel.
(2) [Reserved]
(C) Mitigation zone observation. Action Proponent personnel must
observe the mitigation zones in accordance with the following:
(1) Action Proponent personnel must observe the mitigation zone for
marine mammals for 15 minutes prior to the deployment of nets and while
nets are deployed.
(2) Nets must be deployed during daylight hours only.
(xxii) Commencement or recommencement conditions. Action Proponents
must not commence or recommence an activity after a marine mammal is
observed within a relevant mitigation zone until one of the following
conditions has been met:
(A) Observed exiting. A Lookout observes the animal exiting the
mitigation zone;
(B) Concluded to have exited. A Lookout concludes that the animal
has exited the mitigation zone based on its observed course, speed, and
movement relative to the mitigation zone;
(C) Clear from additional sightings. A Lookout affirms the
mitigation zone has been clear from additional sightings for the
activity-specific wait period; or
(D) Platform or target transit. For mobile events, the platform or
target has transited a distance equal to double the mitigation zone
size beyond the location of the last sighting.
(xxiii) Exceptions to activity-based mitigation for acoustic and
explosive stressors and non-explosive ordnance. Activity-based
mitigation for acoustic and explosive stressors and non-explosive
ordnance will not apply to:
(A) Acoustic sources not operated under positive control (e.g.,
moored oceanographic sources);
(B) Acoustic sources used for safety of navigation (e.g.,
fathometers);
(C) Acoustic sources used or deployed by aircraft operating at high
altitudes (e.g., bombs deployed from high altitude (since personnel
cannot effectively observe the surface of the water));
(D) Acoustic sources used, deployed, or towed by unmanned platforms
except when escort vessels are already participating in the event and
have positive control over the source;
(E) Acoustic sources used by submerged submarines (e.g., sonar
(since they cannot conduct visual observation));
(F) De minimis acoustic sources (e.g., those >200 kHz);
(G) Vessel-based, unmanned vehicle-based, or towed in-water
acoustic sources when marine mammals (e.g., dolphins) are determined to
be intentionally swimming at the bow or alongside or directly behind
the vessel, vehicle, or device (e.g., to bow-ride or wake-ride);
(H) Explosives deployed by aircraft operating at high altitudes;
(I) Explosives deployed by submerged submarines, except for
explosive torpedoes;
(J) Explosives deployed against aerial targets;
(K) Explosives during vessel-launched or shore-launched missile or
rocket events;
(L) Explosives used at or below the de minimis threshold;
(M) Explosives deployed by unmanned platforms except when escort
vessels are already participating in the event and have positive
control over the explosive;
(N) Non-explosive ordnance deployed by aircraft operating at high
altitudes;
(O) Non-explosive ordnance deployed against aerial targets and
land-based targets;
(P) Non-explosive ordnance deployed during vessel- or shore-
launched missile or rocket events; and
(Q) Non-explosive ordnance deployed by unmanned platforms except
when escort vessels are already participating in the event and have
positive control over ordnance deployment.
(xxiv) Exceptions to activity-based mitigation for physical
disturbance and strike stressors. Activity-based mitigation for
physical disturbance and strike stressors will not be implemented:
(A) By submerged submarines;
(B) By unmanned vehicles except when escort vessels are already
participating in the event and have positive control over the unmanned
vehicle movements;
(C) When marine mammals (e.g., dolphins) are determined to be
intentionally swimming at the bow, alongside the vessel or vehicle, or
directly behind the vessel or vehicle (e.g., to bow-ride or wake-ride);
(D) When pinnipeds are hauled out on man-made navigational
structures, port structures, and vessels;
(E) By manned surface vessels and towed in-water devices actively
participating in cable laying during Modernization & Sustainment of
Ranges activities; and
(F) When impractical based on mission requirements (e.g., during
certain aspects of amphibious exercises).
(2) Geographic mitigation areas. The Action Proponents must
implement the geographic mitigation requirements described in
paragraphs (a)(2)(i) through (a)(2)(xi) of this section.
(i) Hawaii Island marine mammal mitigation area. Figure 1 to this
paragraph (a)(2) shows the location of the mitigation areas. Within the
Hawaii Island marine mammal mitigation area, the following requirements
apply (year-round):
(A) Surface ship hull-mounted mid-frequency active sonar. The
Action Proponents must not use more than 300 hours of MF1 surface ship
hull-mounted mid-frequency active sonar or 20 hours of helicopter
dipping sonar (a mid-frequency active sonar source) annually within the
mitigation area.

[[Page 32343]]

(B) In-water explosives. The Action Proponents must not detonate
in-water explosives (including underwater explosives and explosives
deployed against surface targets) within the mitigation area.
(ii) Hawaii 4-Islands marine mammal mitigation area. Figure 1 to
this paragraph (a)(2) shows the location of the mitigation areas.
Within the Hawaii 4-Islands marine mammal mitigation area, the
following requirements apply:
(A) Surface ship hull-mounted mid-frequency active sonar. From
November 15-April 15, the Action Proponents must not use MF1 surface
ship hull-mounted mid-frequency active sonar within the mitigation
area.
(B) In-water explosives. The Action Proponents must not detonate
in-water explosives (including underwater explosives and explosives
deployed against surface targets) within the mitigation area (year-
round).
(iii) Hawaii humpback whale special reporting mitigation area.
Figure 1 to this paragraph (a)(2) shows the location of the mitigation
areas. Within the Hawaii humpback whale special reporting mitigation
area, the following requirements apply:
(A) Surface ship hull-mounted mid-frequency active sonar. The
Action Proponents must report the total hours of MF1 surface ship hull-
mounted mid-frequency active sonar used from November through May in
the mitigation area in their training and testing activity reports
submitted to NMFS.
(B) [Reserved]
(iv) Hawaii humpback whale awareness notification mitigation area.
Figure 1 to this paragraph (a)(2) shows the location of the mitigation
areas. Within the Hawaii humpback whale awareness notification
mitigation area, the following requirements apply:
(A) Hawaii humpback whale awareness notification mitigation area
notifications. The Action Proponents must broadcast awareness
notification messages to alert applicable assets (and their Lookouts)
transiting and training or testing in the Hawaii Range Complex to the
possible presence of concentrations of humpback whales from November
through May.
(B) Visual observations. Lookouts must use that knowledge to help
inform their visual observations during military readiness activities
that involve vessel movements, active sonar, in-water explosives
(including underwater explosives and explosives deployed against
surface targets), or the deployment of non-explosive ordnance against
surface targets in the mitigation area.
(v) Northern California large whale mitigation area. Figure 2 to
this paragraph (a)(2) shows the location of the mitigation areas.
Within the Northern California large whale mitigation area, the
following requirements apply:
(A) Surface ship hull-mounted mid-frequency active sonar. From June
1-October 31, the Action Proponents must not use more than 300 hours of
MF1 surface ship hull-mounted mid-frequency active sonar (excluding
normal maintenance and systems checks) total during training and
testing within the combination of this mitigation area, the Central
California Large Whale Mitigation Area, and the Southern California
Blue Whale Mitigation Area.
(B) [Reserved]
(vi) Central California large whale mitigation area. Figure 2 to
this paragraph (a)(2) shows the location of the mitigation areas.
Within the Central California large whale mitigation area, the
following requirements apply:
(A) Surface ship hull-mounted mid-frequency active sonar. From June
1-October 31, the Action Proponents must not use more than 300 hours of
MF1 surface ship hull-mounted mid-frequency active sonar (excluding
normal maintenance and systems checks) total during training and
testing within the combination of this mitigation area, the Northern
California Large Whale Mitigation Area, and the Southern California
Blue Whale Mitigation Area.
(B) [Reserved]
(vii) Southern California blue whale mitigation area. Figure 2 to
this paragraph (a)(2) shows the location of the mitigation areas.
Within the Southern California blue whale mitigation area, the
following requirements apply:
(A) Surface ship hull-mounted mid-frequency active sonar. From June
1-October 31, the Action Proponents must not use more than 300 hours of
MF1 surface ship hull-mounted mid-frequency active sonar (excluding
normal maintenance and systems checks) total during training and
testing within the combination of this mitigation area, the Northern
California Large Whale Mitigation Area, and the Central California
Large Whale Mitigation Area.
(B) In-water explosives. From June 1-October 31, the Action
Proponents must not detonate in-water explosives (including underwater
explosives and explosives deployed against surface targets) during
large-caliber gunnery, torpedo, bombing, and missile (including 2.75-
inch rockets) training and testing.
(viii) California large whale awareness messages. Figure 2 to this
paragraph (a)(2) shows the location of the mitigation areas. For
California large whale awareness messages, the following requirements
apply:
(A) California large whale awareness messages. The Action
Proponents must broadcast awareness messages to alert applicable assets
(and their Lookouts) transiting and training or testing off the U.S.
West Coast to the possible presence of concentrations of large whales,
including gray whales (November-March), fin whales (November-May), and
mixed concentrations of blue, humpback, and fin whales that may occur
based on predicted oceanographic conditions for a given year (e.g.,
May-November, April-November).
(B) [Reserved]
(ix) California large whale real-time notification mitigation area.
Figure 2 to this paragraph (a)(2) shows the location of the mitigation
areas. Within the California large whale real-time notification
mitigation area, the following requirements apply:
(A) California large whale real-time notification mitigation area
notifications. The Action Proponents will issue real-time notifications
to alert Action Proponent vessels operating in the vicinity of large
whale aggregations (four or more whales) sighted within 1 nmi (1.9 km)
of an Action Proponent vessel within an area of the Southern California
Range Complex (between 32-33 degrees North and 117.2-119.5 degrees
West).
(B) [Reserved]
(x) San Nicolas Island pinniped haulout mitigation area. Figure 2
to this paragraph (a)(2) shows the location of the mitigation areas.
Within the San Nicolas Island pinniped haulout mitigation area, the
following requirements apply:
(A) Haulouts. Navy personnel must not enter pinniped haulout or
rookery areas. Personnel may be adjacent to pinniped haulouts and
rookery prior to and following a launch for monitoring purposes.
(B) Missile and target use. Missiles and targets must not cross
over pinniped haulout areas at altitudes less than 305 m (1,000 ft),
except in emergencies or for real-time security incidents. For unmanned
aircraft systems (UAS), the following minimum altitudes will be
maintained over pinniped haulout areas and rookeries: Class 0-2 UAS
will maintain a minimum altitude of 300 ft; Class 3 UAS will maintain a
minimum altitude of

[[Page 32344]]

500 ft; Class 4 or 5 UAS will not be flown below 1,000 ft.
(C) Number of events. The Navy may not conduct more than 40 launch
events annually and 10 launch events at night annually.
(D) Scheduling. Launch events must be scheduled to avoid the peak
pinniped pupping seasons (from January through July) to the maximum
extent practicable.
(E) Monitoring plan. The Navy must implement a monitoring plan
using video and acoustic monitoring of up to three pinniped haulout
areas and rookeries during launch events that include missiles or
targets that have not been previously monitored for at least three
launch events.
(F) Review of launch procedure. The Navy must review the launch
procedure and monitoring methods, in cooperation with NMFS, if any
incidents of injury or mortality of a pinniped are discovered during
post-launch surveys, or if surveys indicate possible effects to the
distribution, size, or productivity of the affected pinniped
populations as a result of the specified activities. If necessary,
appropriate changes will be made through modification to the LOA prior
to conducting the next launch of the same vehicle.
(xi) National security requirement. Should national security
require the Action Proponents to exceed a requirement(s) in paragraphs
(a)(2)(i) through (a)(2)(x) of this section, Action Proponent personnel
must provide NMFS with advance notification and include the information
(e.g., sonar hours, explosives usage) in its annual activity reports
submitted to NMFS.
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Figure 1 to Paragraph (a)(2)--Geographic Mitigation Areas for Marine
Mammals in the Hawaii Study Area

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[GRAPHIC] [TIFF OMITTED] TP16JY25.003

Figure 2 to Paragraph (a)(2)--Geographic Mitigation Areas for Marine
Mammals in the California Study Area

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[GRAPHIC] [TIFF OMITTED] TP16JY25.004

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(b) [Reserved]

Sec. 218.75 Requirements for monitoring and reporting.

The Action Proponents must implement the following monitoring and
reporting requirements when conducting the specified activities:
(a) Notification of take. If the Action Proponent reasonably
believes that the specified activity identified in Sec. 218.70
resulted in the mortality or serious injury of any marine mammals, or
in any Level A harassment or Level B harassment of marine mammals not
identified in this subpart, then the Action Proponent shall notify NMFS
immediately or as soon as operational security considerations allow.
(b) Monitoring and reporting under the LOAs. The Action Proponents
must conduct all monitoring and reporting required under the LOAs.

[[Page 32347]]

(c) Notification of injured, live stranded, or dead marine mammals.
Action Proponent personnel must abide by the Notification and Reporting
Plan, which sets out notification, reporting, and other requirements
when dead, injured, or live stranded marine mammals are detected. The
Notification and Reporting Plan is available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
(d) Annual HCTT Study Area marine species monitoring report. The
Action Proponents must submit an annual HCTT Study Area marine species
monitoring report describing the implementation and results from the
previous calendar year. Data collection methods will be standardized
across range complexes and the HCTT Study Area to allow for comparison
in different geographic locations. The draft report must be submitted
to the Director, Office of Protected Resources, NMFS, annually. NMFS
will submit comments or questions on the report, if any, within 3
months of receipt. The report will be considered final after the Action
Proponents have addressed NMFS' comments, or 3 months after submittal
of the draft if NMFS does not provide comments on the draft report. The
report must describe progress of knowledge made with respect to
intermediate scientific objectives within the HCTT Study Area
associated with the Integrated Comprehensive Monitoring Program (ICMP).
Similar study questions must be treated together so that progress on
each topic can be summarized across all Navy ranges. The report need
not include analyses and content that do not provide direct assessment
of cumulative progress on the monitoring plan study questions.
(e) Quick look reports. In the event that the sound levels analyzed
in promulgation of these regulations were exceeded within a given
reporting year, the Action Proponents must submit a preliminary
report(s) detailing the exceedance within 21 days after the anniversary
date of issuance of the LOAs.
(f) Annual HCTT Training and Testing Reports. Regardless of whether
analyzed sound levels were exceeded, the Navy must submit a detailed
report (HCTT Annual Training Exercise Report and Testing Activity
Report) and the Coast Guard and Army must each submit a detailed report
(HCTT Annual Training Exercise Report) to the Director, Office of
Protected Resources, NMFS annually. NMFS will submit comments or
questions on the reports, if any, within 1 month of receipt. The
reports will be considered final after the Action Proponents have
addressed NMFS' comments, or 1 month after submittal of the drafts if
NMFS does not provide comments on the draft reports. The annual reports
must contain a summary of all sound sources used (total hours or
quantity (per the LOAs) of each bin of sonar or other non-impulsive
source; total annual number of each type of explosive exercises; and
total annual expended/detonated rounds (missiles, bombs, sonobuoys,
etc.) for each explosive bin). The annual reports must also contain
cumulative sonar and explosive use quantity from previous years'
reports through the current year. Additionally, if there were any
changes to the sound source allowance in the reporting year, or
cumulatively, the reports would include a discussion of why the change
was made and include analysis to support how the change did or did not
affect the analysis in the 2024 HCTT Draft EIS/OEIS and MMPA final
rule. The annual reports must also include the details regarding
specific requirements associated with the mitigation areas listed in
paragraph (f)(4) of this section. The analysis in the detailed report
must be based on the accumulation of data from the current year's
report and data collected from previous annual reports. The detailed
reports shall also contain special reporting for the Hawaii Humpback
Whale Special Reporting Mitigation Area, as described in the LOAs. The
final annual/close-out reports at the conclusion of the authorization
period (year 7) will also serve as the comprehensive close-out reports
and include both the final year annual incidental take compared to
annual authorized incidental take as well as a cumulative 7-year
incidental take compared to 7-year authorized incidental take. The HCTT
Annual Training and Testing Reports must include the specific
information described in the LOAs.
(1) MTEs. This section of the report must contain the following
information for MTEs completed that year in the HCTT Study Area.
(i) Exercise information (for each MTE). For exercise information
(for each MTE):
(A) Exercise designator.
(B) Date that exercise began and ended.
(C) Location.
(D) Number and types of active sonar sources used in the exercise.
(E) Number and types of passive acoustic sources used in exercise.
(F) Number and types of vessels, aircraft, and other platforms
participating in each exercise.
(G) Total hours of all active sonar source operation.
(H) Total hours of each active sonar source bin.
(I) Wave height (high, low, and average) during exercise.
(ii) Individual marine mammal sighting information for each
sighting in each exercise where mitigation was implemented. For
individual marine mammal sighting information for each sighting in each
exercise where mitigation was implemented:
(A) Date, time, and location of sighting.
(B) Species (if not possible, indication of whale/dolphin/
pinniped).
(C) Number of individuals.
(D) Initial Detection Sensor (e.g., passive sonar, Lookout).
(E) Indication of specific type of platform observation was made
from (including, for example, what type of surface vessel or testing
platform).
(F) Length of time observers maintained visual contact with marine
mammal.
(G) Sea state.
(H) Visibility.
(I) Sound source in use at the time of sighting.
(J) Indication of whether animal was less than 200 yd (182.9 m),
200 to 500 yd (182.9 to 457.2 m), 500 to 1,000 yd (457.2 m to 914.4 m),
1,000 to 2,000 yd (914.4 m to 1,828.8 m), or greater than 2,000 yd
(1,828.8 m) from sonar source.
(K) Whether operation of sonar sensor was delayed, or sonar was
powered or shut down, and the length of the delay.
(L) If source in use was hull-mounted, true bearing of animal from
the vessel, true direction of vessel's travel, and estimation of
animal's motion relative to vessel (opening, closing, parallel).
(M) Lookouts must report, in plain language and without trying to
categorize in any way, the observed behavior of the animal(s) (such as
animal closing to bow ride, paralleling course/speed, floating on
surface and not swimming, etc.) and if any calves were present.
(iii) An evaluation (based on data gathered during all of the MTEs)
of the effectiveness of mitigation measures designed to minimize the
received level to which marine mammals may be exposed. For an
evaluation (based on data gathered during all of the MTEs) of the
effectiveness of mitigation measures designed to minimize the received
level to which marine mammals may be exposed:
(A) This evaluation must identify the specific observations that
support any conclusions the Navy reaches about the effectiveness of the
mitigation.
(B) [Reserved]

[[Page 32348]]

(2) Sinking Exercises. This section of the report must include the
following information for each SINKEX completed that year in the HCTT
Study Area:
(i) Exercise information. For exercise information:
(A) Location.
(B) Date and time exercise began and ended.
(C) Total hours of observation by Lookouts before, during, and
after exercise.
(D) Total number and types of explosive source bins detonated.
(E) Number and types of passive acoustic sources used in exercise.
(F) Total hours of passive acoustic search time.
(G) Number and types of vessels, aircraft, and other platforms
participating in exercise.
(H) Wave height in feet (high, low, and average) during exercise.
(I) Narrative description of sensors and platforms utilized for
marine mammal detection and timeline illustrating how marine mammal
detection was conducted.
(ii) Individual marine mammal observation (by Action Proponent
Lookouts) information for each sighting where mitigation was
implemented. For individual marine mammal observation (by Action
Proponent Lookouts) information for each sighting where mitigation was
implemented:
(A) Date/Time/Location of sighting.
(B) Species (if not possible, indicate whale, dolphin, or
pinniped).
(C) Number of individuals.
(D) Initial detection sensor (e.g., sonar or Lookout).
(E) Length of time observers maintained visual contact with marine
mammal.
(F) Sea state.
(G) Visibility.
(H) Whether sighting was before, during, or after detonations/
exercise, and how many minutes before or after.
(I) Distance of marine mammal from actual detonations (or target
spot if not yet detonated): Less than 200 yd (182.9 m), 200 to 500 yd
(182.9 to 457.2 m), 500 to 1,000 yd (457.2 m to 914.4 m), 1,000 to
2,000 yd (914.4 m to 1,828.8 m), or greater than 2,000 yd (1,828.8 m).
(J) Lookouts must report the observed behavior of the animal(s) in
plain language and without trying to categorize in any way (such as
animal closing to bow ride, paralleling course/speed, floating on
surface and not swimming etc.), including speed and direction and if
any calves were present.
(K) The report must indicate whether explosive detonations were
delayed, ceased, modified, or not modified due to marine mammal
presence and for how long.
(L) If observation occurred while explosives were detonating in the
water, indicate munition type in use at time of marine mammal
detection.
(3) Summary of sources used. This section of the report must
include the following information summarized from the authorized sound
sources used in all training and testing events:
(i) Totals for sonar or other acoustic source bins. Total annual
hours or quantity (per the LOA) of each bin of sonar or other acoustic
sources (e.g., pile driving and air gun activities); and
(ii) Total for explosive bins. Total annual expended/detonated
ordnance (missiles, bombs, sonobuoys, etc.) for each explosive bin.
(4) Special Reporting for Geographic Mitigation Areas. This section
of the report must contain the following information for activities
conducted in geographic mitigation areas in the HCTT Study Area:
(i) Hawaii Humpback Whale Special Reporting Mitigation Area. The
Action Proponents must report the total hours of MF1 surface ship hull-
mounted mid-frequency active sonar used from November through May in
the mitigation area.
(ii) National security requirement. If an Action Proponent(s)
invokes the national security requirement described in Sec. 218.74
(a)(2)(xi), the Action Proponent personnel must include information
about the event in its Annual HCTT Training and Testing Report.
(g) MTE sonar exercise notification. The Action Proponents must
submit to NMFS (contact as specified in the LOAs) an electronic report
within 15 calendar days after the completion of any MTE indicating:
(1) Location. Location of the exercise;
(2) Dates. Beginning and end dates of the exercise; and
(3) Type. Type of exercise.

Sec. 218.76 Letters of Authorization.

(a) To incidentally take marine mammals pursuant to this subpart,
the Action Proponents must apply for and obtain LOAs.
(b) An LOA, unless suspended or revoked, may be effective for a
period of time not to exceed the expiration date of this subpart.
(c) In the event of projected changes to the activity or to
mitigation, monitoring, or reporting measures (excluding changes made
pursuant to the adaptive management provision of Sec. 218.77(c)(1))
required by an LOA, the Action Proponent must apply for and obtain a
modification of the LOA as described in Sec. 218.77.
(d) Each LOA will set forth:
(1) Permissible methods of incidental taking;
(2) Geographic areas for incidental taking;
(3) Means of effecting the least practicable adverse impact (i.e.,
mitigation) on the species and stocks of marine mammals and their
habitat; and
(4) Requirements for monitoring and reporting.
(e) Issuance of the LOA(s) must be based on a determination that
the level of taking is consistent with the findings made for the total
taking allowable under the regulations of this subpart.
(f) Notice of issuance or denial of the LOA(s) will be published in
the Federal Register within 30 days of a determination.

Sec. 218.77 Modifications of Letters of Authorization.

(a) An LOA issued under Sec. Sec. 216.106 of this chapter and
218.76 for the activity identified in Sec. 218.70(c) shall be
modified, upon request by the LOA Holder, provided that:
(1) The specified activity and mitigation, monitoring, and
reporting measures, as well as the anticipated impacts, are the same as
those described and analyzed for the regulations in this subpart
(excluding changes made pursuant to the adaptive management provision
in paragraph (c)(1) of this section); and
(2) NMFS determines that the mitigation, monitoring, and reporting
measures required by the previous LOAs under this subpart were
implemented.
(b) For LOA modification requests by the applicants that include
changes to the activity or to the mitigation, monitoring, or reporting
measures (excluding changes made pursuant to the adaptive management
provision in paragraph (c)(1) of this section), the LOA should be
modified provided that:
(1) NMFS determines that the change(s) to the activity or the
mitigation, monitoring or reporting do not change the findings made for
the regulations and do not result in more than a minor change in the
total estimated number of takes (or distribution by species or stock or
years), and
(2) NMFS may publish a notice of proposed modified LOA in the
Federal Register, including the associated analysis of the change, and
solicit public comment before issuing the LOA.
(c) An LOA issued under Sec. Sec. 216.106 and 218.76 of this
chapter for the activities identified in Sec. 218.70(c) may be
modified by NMFS Office of Protected Resources under the following
circumstances:

[[Page 32349]]

(1) After consulting with the Action Proponents regarding the
practicability of the modifications, through adaptive management, NMFS
may modify (including remove, revise or add to) the existing
mitigation, monitoring, or reporting measures if doing so creates a
reasonable likelihood of more effectively accomplishing the goals of
the mitigation and monitoring measures set forth in this subpart.
(i) Possible sources of data that could contribute to the decision
to modify the mitigation, monitoring, or reporting measures in an LOA
include, but are not limited to:
(A) Results from the Action Proponents' monitoring report and
annual exercise reports from the previous year(s);
(B) Results from other marine mammal and/or sound research or
studies; or
(C) Any information that reveals marine mammals may have been taken
in a manner, extent, or number not authorized by this subpart or
subsequent LOAs.
(ii) If, through adaptive management, the modifications to the
mitigation, monitoring, or reporting measures are substantial, NMFS
shall publish a notice of proposed LOA(s) in the Federal Register and
solicit public comment.
(2) If the NMFS Office of Protected Resources determines that an
emergency exists that poses a significant risk to the well-being of the
species or stocks of marine mammals specified in LOAs issued pursuant
to Sec. Sec. 216.106 of this chapter and 218.76, a LOA may be modified
without prior notice or opportunity for public comment. Notice would be
published in the Federal Register within 30 days of the action.

Sec. Sec. 218.78-218.79 [Reserved]

[FR Doc. 2025-13258 Filed 7-15-25; 8:45 am]
BILLING CODE 3510-22-P