[Federal Register Volume 85, Number 106 (Tuesday, June 2, 2020)]
[Proposed Rules]
[Pages 33914-34048]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-08533]



[[Page 33913]]

Vol. 85

Tuesday,

No. 106

June 2, 2020

Part III





Department of Commerce





-----------------------------------------------------------------------





National Oceanic and Atmospheric Administration





-----------------------------------------------------------------------





50 CFR Part 218





Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to the U.S. Navy Training and Testing Activities in the Northwest 
Training and Testing (NWTT) Study Area; Proposed Rule

  Federal Register / Vol. 85, No. 106 / Tuesday, June 2, 2020 / 
Proposed Rules  

[[Page 33914]]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[200417-0114]
RIN 0648-BJ30


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to the U.S. Navy Training and Testing Activities in the 
Northwest Training and Testing (NWTT) Study Area

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

ACTION: Proposed rule; request for comments and information.

-----------------------------------------------------------------------

SUMMARY: NMFS has received a request from the U.S. Navy (Navy) to take 
marine mammals incidental to training and testing activities conducted 
in the Northwest Training and Testing (NWTT) Study Area. Pursuant to 
the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on 
its proposal to issue regulations and subsequent Letters of 
Authorization (LOAs) to the Navy to incidentally take marine mammals 
during the specified activities. NMFS will consider public comments 
prior to issuing any final rule and making final decisions on the 
issuance of the requested LOAs. Agency responses to public comments 
will be provided in the notice of the final decision. The Navy's 
activities qualify as military readiness activities pursuant to the 
MMPA, as amended by the National Defense Authorization Act for Fiscal 
Year 2004 (2004 NDAA).

DATES: Comments and information must be received no later than July 17, 
2020.

ADDRESSES: You may submit comments on this document, identified by 
NOAA-NMFS-2020-0055, by any of the following methods:
     Electronic submission: Submit all electronic public 
comments via the Federal e-Rulemaking Portal. Go to 
www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2020-0055, click the 
``Comment Now!'' icon, complete the required fields, and enter or 
attach your comments.
     Mail: Submit written comments to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service, 1315 East-West Highway, Silver 
Spring, MD 20910.
    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 on 
www.regulations.gov without change. All personal identifying 
information (e.g., name, address), 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 Navy's application and other supporting documents and 
documents cited herein may be obtained online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems 
accessing these documents, please use the contact listed here (see FOR 
FURTHER INFORMATION CONTACT).

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

SUPPLEMENTARY INFORMATION:

Purpose of Regulatory Action

    These proposed regulations, issued under the authority of the MMPA 
(16 U.S.C. 1361 et seq.), would provide the framework for authorizing 
the take of marine mammals incidental to the Navy's training and 
testing activities (which qualify as military readiness activities) 
from the use of sonar and other transducers, in-water detonations, and 
potential vessel strikes based on Navy movement in the NWTT Study Area. 
The Study Area includes air and water space off the coast of 
Washington, Oregon, and northern California; in the Western Behm Canal, 
Alaska; and portions of waters of the Strait of Juan de Fuca and Puget 
Sound, including Navy pierside and harbor locations in Puget Sound (see 
Figure 1-1 of the Navy's rulemaking/LOA application).
    NMFS received an application from the Navy requesting seven-year 
regulations and authorizations to incidentally take individuals of 
multiple species of marine mammals (``Navy's rulemaking/LOA 
application'' or ``Navy's application''). Take is anticipated to occur 
by Level A harassment and Level B harassment as well as a very small 
number of serious injuries or mortalities incidental to the Navy's 
training and testing activities.

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA 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 issued or, if the taking 
is limited to harassment, the public is provided with notice of the 
proposed incidental take authorization and provided the opportunity to 
review and submit comments.
    An authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stocks and will not have an unmitigable adverse impact on the 
availability of the species or stocks for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and 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 such species or stocks for 
taking for certain subsistence uses (referred to in this rule as 
``mitigation measures''); and requirements pertaining to the monitoring 
and reporting of such takings. The MMPA defines ``take'' to mean to 
harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or 
kill any marine mammal. The Preliminary Analysis and Negligible Impact 
Determination section below discusses the definition of ``negligible 
impact.''
    The NDAA for Fiscal Year 2004 (2004 NDAA) (Pub. L. 108-136) amended 
section 101(a)(5) of the MMPA to remove the ``small numbers'' and 
``specified geographical region'' provisions indicated above and 
amended the definition of ``harassment'' as applied to a ``military 
readiness activity.'' The definition of harassment for military 
readiness activities (Section 3(18)(B) of the MMPA) is (i) 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 (ii) 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

[[Page 33915]]

point where such behavioral patterns are abandoned or significantly 
altered (Level B harassment). In addition, the 2004 NDAA amended the 
MMPA as it relates to military readiness activities such that the least 
practicable adverse impact analysis shall include consideration of 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    More recently, Section 316 of the NDAA for Fiscal Year 2019 (2019 
NDAA) (Pub. L. 115-232), signed on August 13, 2018, amended the MMPA to 
allow incidental take rules for military readiness activities under 
section 101(a)(5)(A) to be issued for up to seven years. Prior to this 
amendment, all incidental take rules under section 101(a)(5)(A) were 
limited to five years.

Summary and Background of Request

    On March 11, 2019, NMFS received an application from the Navy for 
authorization to take marine mammals by Level A harassment and Level B 
harassment incidental to training and testing activities (which qualify 
as military readiness activities) from the use of sonar and other 
transducers and in-water detonations in the NWTT Study Area over a 
seven-year period beginning when the current authorization expires. In 
addition, the Navy requested incidental take authorization by serious 
injury or mortality for up to three takes of large whales from vessel 
strikes over the seven-year period. We received revised applications on 
June 6, 2019 and June 21, 2019 which provided revisions in the take 
number estimates and vessel strike analysis and Navy's rulemaking/LOA 
application was found to be adequate and complete. On August 6, 2019 
(84 FR 38225), we published a notice of receipt (NOR) of application in 
the Federal Register, requesting comments and information related to 
the Navy's request for 30 days. We reviewed and considered all comments 
and information received on the NOR in development of this proposed 
rule. On October 4, 2019, the Navy submitted an amendment to its 
application which incorporated new Southern Resident killer whale 
offshore density information, and on December 19, 2019, the Navy 
submitted an amendment to its application which incorporated revised 
testing activity numbers.
    The following types of training and testing, which are classified 
as military readiness activities pursuant to the MMPA, as amended by 
the 2004 NDAA, would be covered under the regulations and LOAs (if 
authorized): Anti-submarine warfare (sonar and other transducers, 
underwater detonations), mine warfare (sonar and other transducers, 
underwater detonations), surface warfare (underwater detonations), and 
other testing and training (sonar and other transducers). The 
activities would not include pile driving/removal or use of air guns.
    This would be the third time NMFS has promulgated incidental take 
regulations pursuant to the MMPA relating to similar military readiness 
activities in the NWTT Study Area, following those effective from 
November 9, 2010 through November 8, 2015 (75 FR 69275; November 10, 
2010) and from November 9, 2015 through November 8, 2020 (80 FR 73555; 
November 24, 2015).
    The Navy's mission is to organize, train, equip, and maintain 
combat-ready naval forces capable of winning wars, deterring 
aggression, and maintaining freedom of the seas. This mission is 
mandated by Federal law (10 U.S.C. 8062), which requires the readiness 
of the naval forces of the United States. The Navy executes this 
responsibility in part by training and testing at sea, often in 
designated operating areas (OPAREA) and testing and training ranges. 
The Navy must be able to access and utilize these areas and associated 
sea space and air space in order 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 ships, aircraft, weapons, combat systems, sensors, and 
related equipment, and conducts scientific research activities to 
achieve and maintain military readiness.
    The Navy has been conducting training and testing activities in the 
NWTT Study Area for decades, with some activities dating back to at 
least the early 1900s. The tempo and types of training and testing 
activities have fluctuated because of the introduction of new 
technologies, the evolving nature of international events, advances in 
warfighting doctrine and procedures, and changes in force structure 
(e.g., organization of ships, submarines, aircraft, weapons, and 
personnel). Such developments influence the frequency, duration, 
intensity, and location of required training and testing activities, 
however the Navy's proposed activities for the period of this proposed 
rule would be largely a continuation of ongoing activities. In addition 
to ongoing activities, the Navy is proposing some new training 
activities such as torpedo exercise--submarine training and unmanned 
underwater vehicle training.\1\ The Navy is also proposing some new 
testing activities, including: At-sea sonar testing, mine 
countermeasure and neutralization testing, mine detection and 
classification testing, kinetic energy weapon testing, propulsion 
testing, undersea warfare testing, vessel signature evaluation, 
acoustic and oceanographic research, radar and other system testing, 
and simulant testing.\2\
---------------------------------------------------------------------------

    \1\ Some of the activities included here are new to the 2019 
NWTT DSEIS/OEIS, but are not new to the Study Area. TORPEX--SUB 
activity was previously analyzed in 2010 as part of the Sinking 
Exercise. The Sinking Exercise is no longer conducted in the NWTT 
Study Area and the TORPEX--SUB activity is now a separate activity 
included in the NWTT DSEIS/OEIS. Unmanned underwater vehicle 
activity was analyzed in 2010 as a testing activity, but is now 
being included as a training activity.
    \2\ Mine detection and classification testing was analyzed in 
2010 in the Inland waters, but was not previously analyzed in the 
Offshore waters. Vessel signature evaluation testing was analyzed in 
2010 as a component to other activities, but is included in the list 
of new activities because it was not previously identified as an 
independent activity.
---------------------------------------------------------------------------

    The Navy's rulemaking/LOA application reflects the most up-to-date 
compilation of training and testing activities deemed necessary by 
senior Navy leadership to accomplish military readiness requirements. 
The types and numbers of activities included in the proposed rule 
account for fluctuations in training and testing in order to meet 
evolving or emergent military readiness requirements. These proposed 
regulations would cover training and testing activities that would 
occur for a seven-year period following the expiration of the current 
MMPA authorization for the NWTT Study Area, which expires on November 
8, 2020.

Description of the Specified Activity

    The Navy requests authorization to take marine mammals incidental 
to conducting training and testing activities. The Navy has determined 
that acoustic and explosives stressors are most likely to result in 
impacts on marine mammals that could rise to the level of harassment, 
and NMFS concurs with this determination. Detailed descriptions of 
these activities are provided in Chapter 2 of the 2019 NWTT Draft 
Supplemental Environmental Impact Statement (SEIS)/Overseas EIS (OEIS) 
(2019 NWTT DSEIS/OEIS) (https://www.nwtteis.com) and in the Navy's 
rulemaking/LOA application (https://www.fisheries.noaa.gov/national/
marine-mammal-protection/incidental-take-authorizations-military-
readiness-activities) and are summarized here.

[[Page 33916]]

Dates and Duration

    The specified activities would occur at any time during the seven-
year period of validity of the regulations. The proposed number of 
training and testing activities are described in the Detailed 
Description of the Specified Activities section (Tables 3 through 4).

Geographical Region

    The NWTT Study Area is composed of established maritime operating 
and warning areas in the eastern North Pacific Ocean region, including 
areas of the Strait of Juan de Fuca, Puget Sound, and Western Behm 
Canal in southeastern Alaska. The Study Area includes air and water 
space within and outside Washington state waters, within Alaska state 
waters, and outside state waters of Oregon and Northern California 
(Figure 1). The eastern boundary of the Offshore Area portion of the 
Study Area is 12 nautical miles (nmi) off the coastline for most of the 
Study Area, including southern Washington, Oregon, and Northern 
California. The Offshore Area includes the ocean all the way to the 
coastline only along that part of the Washington coast that lies 
beneath the airspace of W-237 and the Olympic Military Operating Area 
(MOA) and the Washington coastline north of the Olympic MOA. The Study 
Area includes four existing range complexes and facilities: The 
Northwest Training Range Complex, the Keyport Range Complex, Carr Inlet 
Operations Area, and the Southeast Alaska Acoustic Measurement Facility 
(Western Behm Canal, Alaska). In addition to these range complexes, the 
Study Area also includes Navy pierside locations where sonar 
maintenance and testing occurs as part of overhaul, modernization, 
maintenance, and repair activities at Naval Base Kitsap, Bremerton; 
Naval Base Kitsap, Bangor; and Naval Station Everett. Additional detail 
can be found in Chapter 2 of the Navy's rulemaking/LOA application.
BILLING CODE 3510-22-P

[[Page 33917]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.002

BILLING CODE 3510-22-C

[[Page 33918]]

Primary Mission Areas

    The Navy categorizes many of its training and testing activities 
into functional warfare areas called primary mission areas. The Navy's 
proposed activities for NWTT generally fall into the following six 
primary mission areas: Air warfare; anti-submarine warfare; electronic 
warfare; expeditionary warfare; mine warfare; and surface warfare. Most 
activities conducted in NWTT are categorized under one of these primary 
mission areas; activities that do not fall within one of these areas 
are listed as ``other activities.'' Each warfare community (surface, 
subsurface, aviation, and expeditionary warfare) may train in some or 
all of these primary mission areas. The research and acquisition 
community also categorizes most, but not all, of its testing activities 
under these primary mission areas. A description of the sonar, 
munitions, targets, systems, and other material used during training 
and testing activities within these primary mission areas is provided 
in Appendix A (Navy Activities Descriptions) of the 2019 NWTT DSEIS/
OEIS.
    The Navy describes and analyzes the effects of its activities 
within the 2019 NWTT DSEIS/OEIS. In its assessment, the Navy concluded 
that sonar and other transducers and underwater detonations were the 
stressors most likely to result in impacts on marine mammals that could 
rise to the level of harassment as defined under the MMPA. Therefore, 
the Navy's rulemaking/LOA application provides the Navy's assessment of 
potential effects from these stressors in terms of the various warfare 
mission areas in which they would be conducted. Those mission areas 
include the following:
     Anti-submarine warfare (sonar and other transducers, 
underwater detonations);
     expeditionary warfare;
     mine warfare (sonar and other transducers, underwater 
detonations);
     surface warfare (underwater detonations); and
     other (sonar and other transducers).
    The Navy's training and testing activities in air warfare and 
electronic warfare do not involve sonar and other transducers, 
underwater detonations, or any other stressors that could result in 
harassment, serious injury, or mortality of marine mammals. Therefore, 
the activities in air warfare and electronic warfare are not discussed 
further in this proposed rule, but are analyzed fully in the 2019 NWTT 
DSEIS/OEIS.
Anti-Submarine Warfare
    The mission of anti-submarine warfare is to locate, neutralize, and 
defeat hostile submarine forces that threaten Navy surface forces. 
Anti-submarine warfare can involve various assets such as aircraft, 
ships, and submarines which 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 
(exercise and explosive), missiles, countermeasure systems, and 
underwater surveillance and communications systems. Tests may be 
conducted as part of a large-scale 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 (at the shoreline), riparian (along a 
river), or coastal environments. Expeditionary warfare is wide ranging 
and includes defense of harbors, operation of remotely operated 
vehicles, defense against swimmers, and boarding/seizure operations. 
Expeditionary warfare training activities include underwater 
construction team training, dive and salvage operations, and insertion/
extraction via air, surface, and subsurface platforms.
Mine Warfare
    The mission of mine warfare is to detect, classify, and avoid or 
neutralize (disable) mines to protect Navy ships and submarines and to 
maintain free access to ports and shipping lanes. Mine warfare also 
includes training and testing in offensive mine laying to gain control 
of or deny the enemy access to sea space. Naval mines can be laid by 
ships, submarines, or aircraft.
    Mine warfare training includes exercises in which ships, aircraft, 
submarines, underwater vehicles, unmanned vehicles, or marine mammal 
detection systems search for mine shapes. Personnel train to destroy or 
disable mines by attaching underwater 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 acoustic, optical, and magnetic detectors intended to hunt, 
locate, and record the positions of mines for avoidance or subsequent 
neutralization. Mine warfare testing and development falls into two 
primary categories: Mine detection and classification, and mine 
countermeasure and neutralization testing. Mine detection and 
classification testing involves the use of air, surface, and subsurface 
vessels; it 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/unmanned surface vehicle-based system that may involve the 
deployment of a towed neutralization system.
    A small percentage of mine warfare activities require the use of 
high-explosives to evaluate and confirm the ability of the system or 
the crews conducting the training to neutralize a high-explosive mine 
under operational conditions. 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.

[[Page 33919]]

Surface Warfare
    The mission of surface warfare is to obtain control of sea space 
from which naval forces may operate, which entails offensive action 
against surface targets while also defending against aggressive actions 
by enemy forces. In the conduct of 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 surface-to-surface gunnery and 
missile exercises, air-to-surface gunnery and missile exercises, 
submarine missile or torpedo launch events, and other munitions against 
surface targets.
    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 munitions 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 Activities
    The Navy conducts other training and testing activities in the 
Study Area that fall outside of the primary mission areas, but support 
overall readiness. Surface ship crews conduct Maritime Security 
Operations events, including maritime security escorts for Navy vessels 
such as Fleet Ballistic Missile Submarines; Visit, Board, Search, and 
Seizure; Maritime Interdiction Operations; Force Protection; Anti-
Piracy Operations, Acoustic Component Testing, Cold Water Support, and 
Hydrodynamic and Maneuverability testing. Anti-terrorism/Force-
protection training will occur as small boat attacks against moored 
ships at one of the Navy's piers inside Puget Sound. Pierside and at-
sea maintenance of ship and submarine sonar is required for systems 
upkeep and systems evaluation.

Description of Stressors

    The Navy uses a variety of sensors, platforms, weapons, and other 
devices, including ones used to ensure the safety of Sailors, to meet 
its mission. Training and testing with these systems may introduce 
acoustic (sound) energy or shock waves from explosives into the 
environment. The proposed training and testing activities were 
evaluated to identify specific components that could act as stressors 
by having direct or indirect impacts on the environment. 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 (including 
prey species) within the NWTT Study Area. Each description contains a 
list of activities that may generate the stressor. Stressor/resource 
interactions that were determined to have de minimis or no impacts 
(e.g., vessel noise, aircraft noise, weapons noise, and explosions in 
air) were not carried forward for analysis in the Navy's rulemaking/LOA 
application. No Major Training Exercises (MTEs) or Sinking Exercise 
(SINKEX) events are proposed in the NWTT Study Area. NMFS reviewed the 
Navy's analysis and conclusions on de minimis sources and finds them 
complete and supportable.

Acoustic Stressors

    Acoustic stressors include acoustic signals emitted into the water 
for a specific purpose, such as sonar, other transducers (devices that 
convert energy from one form to another--in this case, into sound 
waves), incidental sources of broadband sound produced as a byproduct 
of vessel movement, aircraft transits, and use of weapons or other 
deployed objects. 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.
    In order to better organize and facilitate the analysis of 
approximately 300 sources of underwater sound used in training and 
testing activities by the Navy, including sonar and other transducers 
and explosives, a series of source classifications, or source bins, 
were developed. The source classification bins do not include the 
broadband noise produced incidental to vessel and aircraft transits and 
weapons firing. Noise produced from vessel, aircraft, and weapons 
firing activities are not carried forward because those activities were 
found to have de minimis or no impacts, as stated above.
    The use of source classification bins provides the following 
benefits:
     Provides the ability for new sensors or munitions to be 
covered 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 a precautionary approach to all impact estimates, 
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) 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 
Navy 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, or listen. In this proposed rule, the terms 
sonar and other transducers will be used to indicate active sound 
sources unless otherwise specified.
    The Navy employs 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, 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, bottom type, water 
depth, temperature, and salinity. The sound received at a particular 
location will be different than near the source due to the

[[Page 33920]]

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 Concepts) of the 2019 NWTT DSEIS/OEIS. Because 
of the complexity of analyzing sound propagation in the ocean 
environment, the Navy relies on acoustic models in its environmental 
analyses that consider sound source characteristics and varying ocean 
conditions across the Study Area.
    The sound sources and platforms typically used in naval activities 
analyzed in the Navy's rulemaking/LOA application are described in 
Appendix A (Navy Activities Descriptions) of the 2019 NWTT DSEIS/OEIS. 
Sonars and other transducers used to obtain and transmit information 
underwater during Navy training and testing 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 feet (ft) 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 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. 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, and at temporary minefields close to strategic ports and harbors, 
or at targets of opportunity such as navigation buoys. Kingfisher mode 
on vessels is most likely to be used when transiting to and from port. 
Sound sources used for imaging could be used throughout the NWTT Study 
Area.

Navigation and Safety

    Similar to commercial and private vessels, Navy 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 (such as underwater modems), 
provide location (pingers), or send a single brief release signal to 
bottom-mounted devices (acoustic release) may be used throughout the 
NWTT Study Area. These sources typically have low duty cycles and are 
usually only used when it is desirable to send a detectable acoustic 
message.

Classification of Sonar and Other Transducers

    Sonars and other transducers are grouped into classes that share an 
attribute, such as frequency range or purpose. As detailed below, 
classes are further sorted by bins based on the frequency or bandwidth; 
source level; and, when warranted, the application in which the source 
would be used. Unless stated otherwise, a reference distance of 1 meter 
(m) 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 and 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:
    [cir] Greater than 160 decibels (dB) referenced to 1 micropascal 
(re: 1 [mu]Pa), but less than 180 dB re: 1 [mu]Pa;
    [cir] Equal to 180 dB re: 1 [mu]Pa and up to 200 dB re: 1 [mu]Pa; 
and
    [cir] Greater than 200 dB re: 1 [mu]Pa.
     Application in which the source would be used:
    [cir] Sources with similar functions that have similar 
characteristics, such as pulse length (duration of each pulse), beam 
pattern, and duty cycle.
    The bins used for classifying active sonars and transducers that 
are quantitatively analyzed in the Study Area are shown in Table 1. 
While general parameters or source characteristics are shown in the 
table, actual source parameters are classified.

Table 1--Sonar and Other Transducers Quantitatively Analyzed in the NWTT
                               Study Area
------------------------------------------------------------------------
      Source class category            Bin             Description
------------------------------------------------------------------------
Low-Frequency (LF): Sources that  LF4            LF sources equal to 180
 produce signals less than 1 kHz. LF5             dB and up to 200 dB.
                                                 LF sources less than
                                                  180 dB.
Mid-Frequency (MF): Tactical and  MF1            Hull-mounted surface
 non-tactical sources that        .............   ship sonars (e.g., AN/
 produce signals between 1 and    MF1K            SQS-53C and AN/SQS-
 10 kHz.                                          60).
                                                 Kingfisher mode
                                                  associated with MF1
                                                  sonars.

[[Page 33921]]

 
                                  MF2            Hull-mounted surface
                                                  ship sonars (e.g., AN/
                                                  SQS-56).
                                  MF3            Hull-mounted submarine
                                                  sonars (e.g., AN/BQQ-
                                                  10).
                                  MF4            Helicopter-deployed
                                                  dipping sonars (e.g.,
                                                  AN/AQS-22).
                                  MF5            Active acoustic
                                                  sonobuoys (e.g.,
                                                  DICASS).
                                  MF6            Underwater sound signal
                                                  devices (e.g., MK 84
                                                  SUS).
                                  MF9            Sources (equal to 180
                                                  dB and up to 200 dB)
                                                  not otherwise binned.
                                  MF10           Active sources (greater
                                                  than 160 dB, but less
                                                  than 180 dB) not
                                                  otherwise binned.
                                  MF11           Hull-mounted surface
                                                  ship sonars with an
                                                  active duty cycle
                                                  greater than 80%.
                                  MF12           Towed array surface
                                                  ship sonars with an
                                                  active duty cycle
                                                  greater than 80%.
High-Frequency (HF): Tactical     HF1            Hull-mounted submarine
 and non-tactical sources that    HF3             sonars (e.g., AN/BQQ-
 produce signals between 10 and                   10).
 100 kHz.                                        Other hull-mounted
                                                  submarine sonars
                                                  (classified).
                                  HF4            Mine detection,
                                                  classification, and
                                                  neutralization sonar
                                                  (e.g., AN/SQS-20).
                                  HF5            Active sources (greater
                                                  than 200 dB) not
                                                  otherwise binned.
                                  HF6            Sources (equal to 180
                                                  dB and up to 200 dB)
                                                  not otherwise binned.
                                  HF8            Hull-mounted surface
                                                  ship sonars (e.g., AN/
                                                  SQS-61).
                                  HF9            Weapon-emulating sonar
                                                  source.
Very High-Frequency (VHF):        VHF1           Active sources greater
 Tactical and non-tactical        VHF2            than 200 dB.
 sources that produce signals                    Active sources with a
 greater than 100 kHz but less                    source level less than
 than 200 kHz.                                    200 dB.
Anti-Submarine Warfare (ASW):     ASW1           MF systems operating
 Tactical sources (e.g., active   ASW2            above 200 dB.
 sonobuoys and acoustic           ASW3           MF Multistatic Active
 countermeasures systems) used                    Coherent sonobuoy
 during ASW training and testing                  (e.g., AN/SSQ-125).
 activities.                                     MF towed active
                                                  acoustic
                                                  countermeasure systems
                                                  (e.g., AN/SLQ-25).
                                  ASW4           MF expendable active
                                                  acoustic device
                                                  countermeasures (e.g.,
                                                  MK 3).
                                  ASW5 \1\       MF sonobuoys with high
                                                  duty cycles.
Torpedoes (TORP): Active          TORP1          Lightweight torpedo
 acoustic signals produced by     .............   (e.g., MK 46, MK 54,
 torpedoes.                       TORP2           or Anti-Torpedo
                                                  Torpedo).
                                                 Heavyweight torpedo
                                                  (e.g., MK 48).
                                  TORP3          Heavyweight torpedo
                                                  (e.g., MK 48).
Looking Sonar (FLS): Forward or   FLS2           HF sources with short
 upward looking object avoidance                  pulse lengths, narrow
 sonars used for ship navigation                  beam widths, and
 and safety.                                      focused beam patterns.
Acoustic Modems (M): Sources      M3             MF acoustic modems
 used to transmit data.                           (greater than 190 dB).
Synthetic Aperture Sonars (SAS):  SAS2           HF SAS systems.
 Sonars used to form high-
 resolution images of the
 seafloor.
Broadband Sound Sources (BB):     BB1            MF to HF mine
 Sonar systems with large         BB2             countermeasure sonar.
 frequency spectra, used for                     HF to VHF mine
 various purposes.                                countermeasure sonar.
------------------------------------------------------------------------
\1\ Formerly ASW2 in the 2015-2020 (Phase II) rulemaking.

Explosive Stressors

    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 in 
the warhead, the type of explosive material, the boundaries and 
characteristics of the propagation medium, and the detonation depth in 
water. The net explosive weight, which is the explosive power of a 
charge expressed as the equivalent weight of trinitrotoluene (TNT), 
accounts for the first two parameters. The effects of these factors are 
explained in Appendix D (Acoustic and Explosive Concepts) of the 2019 
NWTT DSEIS/OEIS. The activities analyzed in the Navy's rulemaking/LOA 
application that use explosives are described in Appendix A (Navy 
Activities Descriptions) of the 2019 NWTT DSEIS/OEIS. Explanations of 
the terminology and metrics used when describing explosives are 
provided in Appendix D (Acoustic and Explosive Concepts) of the 2019 
NWTT DSEIS/OEIS.
Explosives in Water
    Explosive detonations during training and testing activities are 
associated with high-explosive munitions, including, but not limited 
to, bombs, missiles, naval gun shells, torpedoes, mines, demolition 
charges, and explosive sonobuoys. Explosive detonations during training 
and testing involving the use of high-explosive munitions, including 
bombs, missiles, and naval gun shells, could 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 could be detonated in the water column or on the 
ocean bottom. Detonations would typically occur in waters greater than 
200 ft in depth, and greater than 50 nmi from shore, with the exception 
of mine countermeasure and neutralization testing proposed in the 
Offshore Area, and existing mine warfare areas in Inland Waters (i.e., 
Crescent Harbor and Hood Canal Explosive Ordnance Disposal Training 
Ranges). Mine countermeasure and neutralization testing is a new 
proposed testing activity that would occur closer to shore than other 
in-water explosive activities

[[Page 33922]]

analyzed in the 2015 NWTT Final EIS/OEIS for the Offshore Area of the 
NWTT Study Area. This activity would occur in waters 3 nmi or greater 
from shore in the Quinault Range Site (outside the Olympic Coast 
National Marine Sanctuary), or 12 nmi or greater from shore elsewhere 
in the Offshore Area. Two of the three events would involve the use of 
explosives, and would typically occur in water depths shallower than 
1,000 ft. The two multi-day events (1-10 days per event) would include 
up to 36 E4 explosives (>2.5-5 lb net explosive weight) and 5 E7 
explosives (>20-60 lb net explosive weight). In order to better 
organize and facilitate the analysis of explosives used by the Navy 
during training and testing that could detonate in water or at the 
water surface, explosive classification bins were developed. The use of 
explosive classification bins provides the same benefits discussed 
above and as described for acoustic source classification bins in 
Section 1.4.1 (Acoustic Stressors) of the Navy's rulemaking/LOA 
application.
    Explosives detonated in water are binned by net explosive weight. 
The bins of explosives that are proposed for use in the Study Area are 
shown in Table 2 below.

 Table 2--Explosive Sources Quantitatively Analyzed That Could Be Used Underwater or at the Water Surface in the
                                                   Study Area
----------------------------------------------------------------------------------------------------------------
                                    Net explosive weight    Example explosive
               Bin                          (lb)                 source          Modeled detonation depths (ft)
----------------------------------------------------------------------------------------------------------------
E1..............................                 0.1-0.25  Medium-caliber      0.3, 60.
                                                            projectiles.
E2..............................                >0.25-0.5  Medium-caliber      0.3.
                                                            projectiles.
E3..............................                 >0.5-2.5  Explosive Ordnance  33, 60.
                                                            Disposal Mine
                                                            Neutralization.
E4..............................                   >2.5-5  Mine                197, 262, 295, 394.
                                                            Countermeasure
                                                            and
                                                            Neutralization.
E5..............................                    >5-10  Large-caliber       0.3.
                                                            projectile.
E7..............................                   >20-60  Mine                33, 98, 230, 295.
                                                            Countermeasure
                                                            and
                                                            Neutralization.
E8..............................                  >60-100  Lightweight         150.
                                                            torpedo.
E10.............................                 >250-500  1,000 lb bomb.....  0.3.
E11.............................                 >500-650  Heavyweight         300, 656.
                                                            torpedo.
----------------------------------------------------------------------------------------------------------------
Notes: Net Explosive Weight refers to the equivalent amount of TNT, the actual weight of a munition may be
  larger due to other components; in = inch(es), lb = pound(s), ft = feet.

    Propagation of explosive pressure waves in water is highly 
dependent on environmental characteristics such as bathymetry, bottom 
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 Concepts) of the 2019 NWTT DSEIS/
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 Navy relies on acoustic models in its environmental 
analyses that consider sound source characteristics and varying ocean 
conditions across the Study Area.
Explosive Fragments
    Marine mammals could be exposed to fragments from underwater 
explosions associated with the specified activities. When explosive 
ordnance (e.g., bomb or missile) detonates, fragments of the weapon are 
thrown at high-velocity from the detonation point, which can injure or 
kill marine mammals if they are struck. These fragments may be of 
variable size and are ejected at supersonic speed from the detonation. 
The casing fragments will be ejected at velocities much greater than 
debris from any target due to the proximity of the casing to the 
explosive material. Risk of fragment injury reduces exponentially with 
distance as the fragment density is reduced. Fragments underwater tend 
to be larger than fragments produced by in-air explosions (Swisdak and 
Montaro, 1992). Underwater, the friction of the water would quickly 
slow these fragments to a point where they no longer pose a threat. 
Opposingly, the blast wave from an explosive detonation moves 
efficiently through the seawater. Because the ranges to mortality and 
injury due to exposure to the blast wave are likely to far exceed the 
zone where fragments could injure or kill an animal, the ranges for 
assessing the likelihood of mortality and injury from a blast, which 
are also used to inform mitigation zones, are assumed to encompass risk 
due to fragmentation.

Other Stressor--Vessel Strike

    NMFS also considered the chance that a vessel utilized in training 
or testing activities could strike a marine mammal. Vessel strikes have 
the potential to result in incidental take from serious injury and/or 
mortality. Vessel strikes are not specific to any particular training 
or testing activity, but rather are a limited, sporadic, and incidental 
result of Navy vessel movement during training and testing activities 
within a 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; Douglas et al., 2008; Laggner, 2009; Lammers et 
al., 2003; Van der Hoop et al., 2012; Van der Hoop et al., 2013), 
although reviews of the literature on ship 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 (Conn and Silber, 2013; 
Gende et al., 2011; Silber et al., 2010; Vanderlaan and Taggart, 2007; 
Wiley et al., 2016). For large vessels, speed and angle of approach can 
influence the severity of a strike.
    Navy vessels transit at speeds that are optimal for fuel 
conservation and to meet training and testing requirements. Vessels 
used as part of the proposed Specified Activities include ships, 
submarines, unmanned vessels, and boats ranging in size from small, 22 
ft (7 m) rigid hull inflatable boats to aircraft carriers with lengths 
up to 1,092 ft (333 m). The average speed of large Navy ships ranges 
between 10 and 15 knots (kn) and submarines generally operate at speeds 
in the range of 8 to 13 kn, while a few specialized vessels can travel 
at faster speeds. Small craft (for

[[Page 33923]]

purposes of this analysis, less than 60 ft (18 m) in length) have much 
more variable speeds (0 to 50+ kn, dependent on the activity), but 
generally range from 10 to 14 kn. From unpublished Navy data, average 
median speed for large Navy ships in the other Navy ranges from 2011-
2015 varied from 5 to 10 kn with variations by ship class and location 
(i.e., slower speeds close to the coast). Similar patterns would occur 
in the NWTT Study Area. A full description of Navy vessels that are 
used during training and testing activities can be found in Chapter 2 
(Description of Proposed Action and Alternatives) of the 2019 NWTT 
DSEIS/OEIS.
    While these speeds are representative of most events, some vessels 
need to temporarily operate outside of these parameters for certain 
times or during certain activities. 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. 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 will be dead in the water or moving slowly ahead to maintain 
steerage.
    Large Navy vessels (greater than 60 ft (18 m) in length) within the 
offshore areas of range complexes and testing ranges operate 
differently from commercial vessels in ways that may reduce potential 
whale collisions. 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 be stopped within a distance appropriate 
to the prevailing circumstances and conditions.

Detailed Description of Proposed Activities

Proposed Training and Testing Activities

    The training and testing activities that the Navy proposes to 
conduct in the NWTT Study Area are summarized in Table 3 (training) and 
Table 4 (testing). The tables are organized according to primary 
mission areas and include the activity name, associated stressor(s) of 
Navy's activities, description and duration of the activity, sound 
source bin, the areas where the activities are conducted in the NWTT 
Study Area, and the number of activities. Under the ``Annual # of 
Events'' column, events show either a single number or a range of 
numbers to indicate the maximum number of times that activity could 
occur during any single year. The ``7-Year # of Events'' is the maximum 
number of times an activity would occur over the 7-year period of 
proposed regulations. For further information regarding the primary 
platform used (e.g., ship or aircraft type) see Appendix A (Training 
and Testing Activities Descriptions) of the 2019 NWTT DSEIS/OEIS.
    The Navy's proposed activities reflect a representative year of 
training and testing to account for the natural fluctuation of training 
and testing cycles and deployment schedules that generally prevents the 
maximum level of activities from occurring year after year in any 7-
year period. As shown in the tables of activities, the number of some 
activities may vary from year to year, and the level of variability can 
differ by activity. Still, the annual analysis assumes a ``maximum'' 
year. For the purposes of this request, the Navy assumes that some 
unit-level training would be conducted using synthetic means (e.g., 
simulators). Additionally, the request assumes that some unit-level 
active sonar training and some testing will be completed during other 
scheduled activities.

                             Table 3--Proposed Training Activities Analyzed for the Seven-Year Period in the NWTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                         Annual   7-Year
   Stressor category         Activity                  Description              Typical  duration      Source bin         Location        # of     # of
                                                                                                                                         events   events
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Anti-Submarine Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic; Explosive...  Torpedo Exercise-- Submarine crews search for, track,   8 hours..........  TORP2............  Offshore Area         0-2        5
                         Submarine          and detect submarines. Event would                                         >12 nmi from
                         (TORPEX--Sub).     include one MK-48 torpedo used                                             land.
                                            during this event.
Acoustic..............  Tracking           Helicopter crews search for, track,  2-4 hours........  MF4, MF5.........  Offshore Area         0-2        5
                         Exercise--Helico   and detect submarines.                                                     >12 nmi from
                         pter (TRACKEX--                                                                               land.
                         Helo).
Acoustic..............  Tracking           Maritime patrol aircraft crews       2-8 hours........  ASW2, ASW5, MF5,   Offshore Area         373    2,611
                         Exercise--Mariti   search for, track, and detect                           TORP1.             >12 nmi from
                         me Patrol          submarines.                                                                land.
                         Aircraft
                         (TRACKEX--MPA).
Acoustic..............  Tracking           Surface ship crews search for,       2-4 hours........  ASW3, MF1, MF11..  Offshore Area...       62      434
                         Exercise--Ship     track, and detect submarines.
                         (TRACKEX--Ship).
Acoustic..............  Tracking           Submarine crews search for, track,   8 hours..........  HF1, MF3.........  Offshore Area...   75-100      595
                         Exercise--Submar   and detect submarines.
                         ine (TRACKEX--
                         Sub).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Mine Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Civilian Port      Maritime security personnel train    Multiple days....  HF4, SAS2........  Inland Waters...      0-1        5
                         Defense--Homelan   to protect civilian ports and
                         d Security Anti-   harbors against enemy efforts to
                         Terrorism/Force    interfere with access to those
                         Protection         ports.
                         Exercises.

[[Page 33924]]

 
Explosive.............  Mine               Personnel disable threat mines       Up to 4 hours....  E3...............  Crescent Harbor        12       84
                         Neutralization--   using explosive charges.                                                   EOD Training
                         Explosive                                                                                     Range, Hood
                         Ordnance                                                                                      Canal EOD
                         Disposal (EOD).                                                                               Training Range.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Surface Warfare
--------------------------------------------------------------------------------------------------------------------------------------------------------
Explosive.............  Bombing Exercise   Fixed-wing aircrews deliver bombs    1 hour...........  E10..............  Offshore Area (W-   * 0-2        5
                         (Air-to-Surface)   against surface targets.                                                   237) >50 nmi
                         (BOMBEX [A-S]).                                                                               from land.
Explosive.............  Gunnery Exercise   Surface ship crews fire large- and   Up to 3 hours....  E1, E2, E5.......  Offshore Area        * 90      504
                         (Surface-to-       medium-caliber guns at surface                                             >50 nmi from
                         Surface)--Ship     targets.                                                                   land.
                         (GUNEX [S-S]--
                         Ship).
Explosive.............  Missile Exercise   Fixed-wing aircrews simulate firing  2 hours..........  E10..............  Offshore Area (W-     0-2        5
                         (Air-to-Surface)   precision-guided missiles, using                                           237) >50 nmi
                         (MISSILEX [A-S]).  captive air training missiles                                              from land.
                                            (CATMs) against surface targets.
                                            Some activities include firing a
                                            missile with a high-explosive (HE)
                                            warhead.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Other Training
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic..............  Submarine Sonar    Maintenance of submarine sonar and   Up to 1 hour.....  LF5, MF3.........  NBK Bangor, NBK        26      182
                         Maintenance.       other system checks are conducted                                          Bremerton, and
                                            pierside or at sea.                                                        Offshore Area
                                                                                                                       >12 nmi from
                                                                                                                       land.
Acoustic..............  Surface Ship       Maintenance of surface ship sonar    Up to 4 hours....  MF1..............  NBK Bremerton,         25      175
                         Sonar              and other system checks are                                                NS Everett, and
                         Maintenance.       conducted pierside or at sea.                                              Offshore Area
                                                                                                                       >12 nmi from
                                                                                                                       land.
Acoustic..............  Unmanned           Unmanned underwater vehicle          Up to 24 hours...  FLS2, M3.........  Inland Waters,         60      420
                         Underwater         certification involves training                                            Offshore Area.
                         Vehicle 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.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* (Counts only the explosive events).


                             Table 4--Proposed Testing Activities Analyzed for the Seven-Year Period in the NWTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                         Annual   7-Year
       Stressor category              Activity            Description        Typical duration       Source bin           Location         # of     # of
                                                                                                                                         events   events
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Naval Sea Systems Command Testing Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Anti-Submarine Warfare:
    Acoustic..................  Anti-Submarine       Ships and their       4-8 hours of active  ASW1, ASW2, ASW3,   Offshore Area.....       44      308
                                 Warfare Testing.     supporting            sonar use.           ASW5, MF1K, MF4,
                                                      platforms (rotary-                         MF5, MF10, MF11,
                                                      wing aircraft and                          MF12, TORP1.
                                                      unmanned aerial
                                                      systems) detect,
                                                      localize, and
                                                      prosecute
                                                      submarines.
    Acoustic..................  At-Sea Sonar         At-sea testing to     From 4 hours to 11   ASW3, HF1, HF5,     Offshore Area.....        4       28
                                 Testing.             ensure systems are    days.                M3, MF3.           Inland Waters           4-6       34
                                                      fully functional in                       ASW3, HF5, TORP1..   (DBRC).
                                                      an open ocean
                                                      environment.
    Acoustic..................  Countermeasure       Countermeasure        From 4 hours to 6    ASW3, ASW4, HF8,    Offshore Area            14       98
                                 Testing.             testing involves      days.                MF1, TORP2.         (QRS).             .......  .......
                                                      the testing of                            ASW3, ASW4........  ..................       29      203
                                                      systems that will                         ..................  Inland Waters       .......  .......
                                                      detect, localize,                         ASW4..............   (DBRC, Keyport           1        5
                                                      and track incoming                                             Range Site).
                                                      weapons, including                                            Western Behm
                                                      marine vessel                                                  Canal, AK.
                                                      targets.
                                                      Countermeasures may
                                                      be systems to
                                                      obscure the
                                                      vessel's location
                                                      or systems to
                                                      rapidly detect,
                                                      track, and counter
                                                      incoming threats.
                                                      Testing includes
                                                      surface ship
                                                      torpedo defense
                                                      systems and marine
                                                      vessel stopping
                                                      payloads.

[[Page 33925]]

 
    Acoustic..................  Pierside-Sonar       Pierside testing to   Up to 3 weeks......  ASW3, HF3, MF1,     Inland Waters (NS     88-99      635
                                 Testing.             ensure systems are                         MF2, MF3, MF9,      Everett, NBK
                                                      fully functional in                        MF10, MF12.         Bangor, NBK
                                                      a controlled                                                   Bremerton).
                                                      pierside
                                                      environment prior
                                                      to at-sea test
                                                      activities.
    Acoustic..................  Submarine Sonar      Pierside, moored,     Up to 3 weeks......  HF6, MF9..........  Western Behm            1-2       10
                                 Testing/             and underway                                                   Canal, AK.
                                 Maintenance.         testing of
                                                      submarine systems
                                                      occurs periodically
                                                      following major
                                                      maintenance periods
                                                      and for routine
                                                      maintenance.
    Acoustic; Explosive.......  Torpedo (Explosive)  Air, surface, or      1-2 hours during     E8, E11, ASW3,      Offshore Area >50         4       28
                                 Testing.             submarine crews       daylight only.       HF1, HF6, MF1,      nmi from land.
                                                      employ explosive                           MF3, MF4, MF5,
                                                      and non-explosive                          MF6, TORP1, TORP2.
                                                      torpedoes against
                                                      artificial targets.
    Acoustic..................  Torpedo (Non-        Air, surface, or      Up to 2 weeks......  ASW3, ASW4, HF1,    Offshore Area.....       22      154
                                 explosive) Testing.  submarine crews                            HF5, HF6, MF1,
                                                      employ non-                                MF3, MF4, MF5,
                                                      explosive torpedoes                        MF6, MF9, MF10,
                                                      against targets,                           TORP1, TORP2.
                                                      submarines, or
                                                      surface vessels.
                                                                                                HF6, LF4, TORP1,    Inland Waters            61      427
                                                                                                 TORP2, TORP3.       (DBRC).
Mine Warfare:
    Acoustic; Explosive.......  Mine Countermeasure  Air, surface, and     1-10 days..........  E4, E7, HF4.......  Offshore Area.....        3       15
                                 and Neutralization   subsurface vessels                        HF4...............  Inland Waters.....        3       13
                                 Testing.             neutralize threat
                                                      mines and mine-like
                                                      objects.
    Acoustic..................  Mine Detection and   Air, surface, and     Up to 24 days......  BB1, BB2, LF4.....  Offshore Area             1        7
                                 Classification       subsurface vessels                        BB1, BB2, HF4, LF4   (QRS).                  42      294
                                 Testing.             and systems detect                                            Inland Waters
                                                      and classify mines                                             (DBRC, Keyport
                                                      and mine-like                                                  Range Site).
                                                      objects. Vessels
                                                      also assess their
                                                      potential
                                                      susceptibility to
                                                      mines and mine-like
                                                      objects.
Unmanned Systems:
    Acoustic..................  Unmanned Underwater  Testing involves the  Typically 1-2 days,  FLS2, HF5, TORP1,   Offshore Area         38-39      269
                                 Vehicle Testing.     production or         up to multiple       VHF1.               (QRS).             371-379    2,615
                                                      upgrade of unmanned   months.             DS3, FLS2, HF5,     Inland Waters
                                                      underwater                                 HF9, M3, SAS2,      (DBRC, Keyport
                                                      vehicles. This may                         VHF1, TORP1.        Range Site, Carr
                                                      include testing of                                             Inlet).
                                                      mission
                                                      capabilities (e.g.,
                                                      mine detection),
                                                      evaluating the
                                                      basic functions of
                                                      individual
                                                      platforms, or
                                                      conducting complex
                                                      events with
                                                      multiple vehicles.
Vessel Evaluation:
    Acoustic..................  Undersea Warfare     Ships demonstrate     Up to 10 days......  ASW3, ASW4, HF4,    Offshore Area.....     1-12       27
                                 Testing.             capability of                              MF1, MF4, MF5,
                                                      countermeasure                             MF6, MF9, TORP1,
                                                      systems and                                TORP2.
                                                      underwater
                                                      surveillance,
                                                      weapons engagement,
                                                      and communications
                                                      systems. This tests
                                                      ships' ability to
                                                      detect, track, and
                                                      engage undersea
                                                      targets.
Other Testing:
    Acoustic..................  Acoustic and         Research using        Up to 14 days......  LF4, MF9..........  Offshore Area             1        7
                                 Oceanographic        active                                                         (QRS).                   3       21
                                 Research.            transmissions from                                            Inland Waters
                                                      sources deployed                                               (DBRC, Keyport
                                                      from ships,                                                    Range Site).
                                                      aircraft, and
                                                      unmanned underwater
                                                      vehicles. Research
                                                      sources can be used
                                                      as proxies for
                                                      current and future
                                                      Navy systems.
    Acoustic..................  Acoustic Component   Various surface       1 day to multiple    HF3, HF6, LF5, MF9  Western Behm          13-18       99
                                 Testing.             vessels, moored       months.                                  Canal, AK.
                                                      equipment, and
                                                      materials are
                                                      tested to evaluate
                                                      performance in the
                                                      marine environment.
    Acoustic..................  Cold Water Support.  Fleet training for    8 hours............  HF6...............  Inland Waters             4       28
                                                      divers in a cold                                               (Keyport Range     .......  .......
                                                      water environment,                                             Site, DBRC, Carr         1        7
                                                      and other diver                                                Inlet).
                                                      training related to                                           Western Behm
                                                      Navy divers                                                    Canal, AK.
                                                      supporting range/
                                                      test site
                                                      operations and
                                                      maintenance.

[[Page 33926]]

 
    Acoustic..................  Post-Refit Sea       Following periodic    8 hours............  HF9, M3, MF10.....  Inland Waters            30      210
                                 Trial.               maintenance periods                                            (DBRC).
                                                      or repairs, sea
                                                      trials are
                                                      conducted to
                                                      evaluate submarine
                                                      propulsion, sonar
                                                      systems, and other
                                                      mechanical tests.
    Acoustic..................  Semi-Stationary      Semi-stationary       From 10 minutes to   HF6, HF9, LF4,      Inland Waters           120      840
                                 Equipment Testing.   equipment (e.g.,      multiple days.       MF9, VHF2.          (DBRC, Keyport     .......  .......
                                                      hydrophones) is                           HF6, HF9..........   Range Site).           2-3       12
                                                      deployed to                                                   Western Behm
                                                      determine                                                      Canal, AK.
                                                      functionality.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Naval Air Systems Command Testing Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Anti-Submarine Warfare:
    Acoustic; Explosive.......  Tracking Test--      The test evaluates    4-8 flight hours...  E1, E3, ASW2,       Offshore Area.....        8       56
                                 Maritime Patrol      the sensors and                            ASW5, MF5, MF6.
                                 Aircraft.            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.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Summary of Acoustic and Explosive Sources Analyzed for Training and 
Testing

    Tables 5 through 8 show the acoustic and explosive source classes, 
bins, and quantity used in either hours or counts associated with the 
Navy's proposed training and testing activities over a seven-year 
period in the NWTT Study Area that were analyzed in the Navy's 
rulemaking/LOA application. Table 5 describes the acoustic source 
classes (i.e., low-frequency (LF), mid-frequency (MF), and high-
frequency (HF)) and numbers that could occur over seven years under the 
proposed training activities. Acoustic source bin use in the proposed 
activities would vary annually. The seven-year totals for the proposed 
training activities take into account that annual variability.

 Table 5--Acoustic Source Class Bins Analyzed and Numbers Used for Seven-Year Period for Training Activities in
                                               the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                                                        7-Year
       Source class category                Bin             Description         Unit       Annual       total
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF): Sources that     LF5               LF sources less than         H             1            5
 produce signals less than 1 kHz.                       180 dB.
Mid-Frequency (MF): Tactical and     MF1               Hull-mounted surface         H           164        1,148
 non-tactical sources that produce                      ship sonars (e.g.,
 signals between 1 and 10 kHz.                          AN/SQS-53C and AN/
                                                        SQS-61).
                                     MF3               Hull-mounted                 H            70          490
                                                        submarine sonars
                                                        (e.g., AN/BQQ-10).
                                     MF4               Helicopter-deployed          H           0-1            1
                                                        dipping sonars
                                                        (e.g., AN/AQS-22 and
                                                        AN/AQS-13).
                                     MF5               Active acoustic               C      918-926        6,443
                                                        sonobuoys (e.g.,
                                                        DICASS).
                                     MF11              Hull-mounted surface         H            16          112
                                                        ship sonars with an
                                                        active duty cycle
                                                        greater than 80%.
High-Frequency (HF): Tactical and    HF1               Hull-mounted                 H            48          336
 non-tactical sources that produce                      submarine sonars
 signals between 10 and 100 kHz.                        (e.g., AN/BQQ-10).
                                     HF4               Mine detection,              H          0-65          269
                                                        classification, and
                                                        neutralization sonar
                                                        (e.g., AN/SQS-20).
Anti-Submarine Warfare (ASW):        ASW2              MF Multistatic Active         C          350        2,450
 Tactical sources (e.g., active                         Coherent sonobuoy
 sonobuoys and acoustic                                 (e.g., AN/SSQ-125).
 countermeasures systems) used
 during ASW training and testing
 activities.
                                     ASW3              MF towed active              H            86          602
                                                        acoustic
                                                        countermeasure
                                                        systems (e.g., AN/
                                                        SLQ-25).
                                     ASW5              MF sonobuoys with            H            50          350
                                                        high duty cycles.
Torpedoes (TORP): Source classes     TORP1             Lightweight torpedo           C           16          112
 associated with the active                             (e.g., MK 46, MK 54,
 acoustic signals produced by                           or Anti-Torpedo
 torpedoes.                                             Torpedo).
                                     TORP2             Heavyweight torpedo           C          0-2            5
                                                        (e.g., MK 48).
Forward Looking Sonar (FLS):         FLS2              HF sources with short        H           240        1,680
 Forward or upward looking object                       pulse lengths,
 avoidance sonars used for ship                         narrow beam widths,
 navigation and safety.                                 and focused beam
                                                        patterns.

[[Page 33927]]

 
Acoustic Modems (M): Systems used    M3                MF acoustic modems           H            30          210
 to transmit data through the water.                    (greater than 190
                                                        dB).
Synthetic Aperture Sonars (SAS):     SAS2              HF SAS systems.......        H         0-561        2,353
 Sonars in which active acoustic
 signals are post-processed to form
 high-resolution images of the
 seafloor.
----------------------------------------------------------------------------------------------------------------
Notes: H = hours; C = count.

    Table 6 describes the acoustic source classes and numbers that 
could occur over seven years under the proposed testing activities. 
Acoustic source bin use in the proposed activities would vary annually. 
The seven-year totals for the proposed testing activities take into 
account that annual variability.

  Table 6--Acoustic Source Class Bins Analyzed and Numbers Used for Seven-Year Period for Testing Activities in
                                               the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                                                        7-Year
       Source class category                Bin             Description         Unit       Annual       total
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF): Sources that     LF4               LF sources equal to          H           177        1,239
 produce signals less than 1 kHz.                       180 dB and up to 200
                                                        dB.
                                     LF5               LF sources less than         H          0-18           23
                                                        180 dB.
Mid-Frequency (MF): Tactical and     MF1               Hull-mounted surface         H        20-169          398
 non-tactical sources that produce                      ship sonars (e.g.,
 signals between 1 and 10 kHz.                          AN/SQS-53C and AN/
                                                        SQS-61).
                                     MF1K              Kingfisher mode              H            48          336
                                                        associated with MF1
                                                        sonars.
                                     MF2               Hull-mounted surface         H            32          224
                                                        ship sonars (e.g.,
                                                        AN/SQS-56).
                                     MF3               Hull-mounted                 H         34-36          239
                                                        submarine sonars
                                                        (e.g., AN/BQQ-10).
                                     MF4               Helicopter-deployed          H         41-50          298
                                                        dipping sonars
                                                        (e.g., AN/AQS-22 and
                                                        AN/AQS-13).
                                     MF5               Active acoustic               C      300-673        2,782
                                                        sonobuoys (e.g.,
                                                        DICASS).
                                     MF6               Active underwater             C       60-232          744
                                                        sound signal devices
                                                        (e.g., MK 84 SUS).
                                     MF9               Active sources (equal        H       644-959        5,086
                                                        to 180 dB and up to
                                                        200 dB) not
                                                        otherwise binned.
                                     MF10              Active sources               H           886        6,197
                                                        (greater than 160
                                                        dB, but less than
                                                        180 dB) not
                                                        otherwise binned.
                                     MF11              Hull-mounted surface         H            48          336
                                                        ship sonars with an
                                                        active duty cycle
                                                        greater than 80
                                                        percent.
                                     MF12              Towed array surface          H           100          700
                                                        ship sonars with an
                                                        active duty cycle
                                                        greater than 80
                                                        percent.
High-Frequency (HF): Tactical and    HF1               Hull-mounted                 H            10           68
 non-tactical sources that produce                      submarine sonars
 signals between 10 and 100 kHz.                        (e.g., AN/BQQ-10).
                                     HF3               Other hull-mounted           H          1-19           30
                                                        submarine sonars
                                                        (classified).
                                     HF4               Mine detection,              H   1,860-1,868       11,235
                                                        classification, and
                                                        neutralization sonar
                                                        (e.g., AN/SQS-20).
                                     HF5               Active sources               H       352-400        2,608
                                                        (greater than 200
                                                        dB) not otherwise
                                                        binned.
                                     HF6               Active sources (equal        H   1,705-1,865       12,377
                                                        to 180 dB and up to
                                                        200 dB) not
                                                        otherwise binned.
                                     HF8               Hull-mounted surface         H            24          168
                                                        ship sonars (e.g.,
                                                        AN/SQS-61).
                                     HF9               Weapon emulating             H           257        1,772
                                                        sonar source.
Very High-Frequency (VHF): Tactical  VHF1              Very high frequency          H           320        2,240
 and non-tactical sources that                          sources greater than
 produce signals greater than 100                       200 dB.
 kHz but less than 200 kHz.
                                     VHF2              Active sources with a        H           135          945
                                                        frequency greater
                                                        than 100 kHz, up to
                                                        200 kHz with a
                                                        source level less
                                                        than 200 dB.
Anti-Submarine Warfare (ASW):        ASW1              MF systems operating         H            80          560
 Tactical sources (e.g., active                         above 200 dB.
 sonobuoys and acoustic
 countermeasures systems) used
 during ASW training and testing
 activities.
                                     ASW2              MF systems operating          C          240        1,680
                                                        above 200 dB.
                                     ASW3              MF towed active              H     487-1,015        4,091
                                                        acoustic
                                                        countermeasure
                                                        systems (e.g., AN/
                                                        SLQ-25).

[[Page 33928]]

 
                                     ASW4              MF expendable active          C  1,349-1,389        9,442
                                                        acoustic device
                                                        countermeasures
                                                        (e.g., MK 3).
                                     ASW5              MF sonobuoys with            H            80          560
                                                        high duty cycles.
Torpedoes (TORP): Source classes     TORP1             Lightweight torpedo           C      298-360        2,258
 associated with the active                             (e.g., MK 46, MK 54,
 acoustic signals produced by                           or Anti-Torpedo
 torpedoes.                                             Torpedo).
                                     TORP2             Heavyweight torpedo           C      332-372        2,324
                                                        (e.g., MK 48).
                                     TORP3             Heavyweight torpedo           C            6           42
                                                        test (e.g., MK 48).
Forward Looking Sonar (FLS):         FLS2              HF sources with short        H            24          168
 Forward or upward looking object                       pulse lengths,
 avoidance sonars used for ship                         narrow beam widths,
 navigation and safety.                                 and focused beam
                                                        patterns.
Acoustic Modems (M): Systems used    M3                MF acoustic modems           H         1,088        7,616
 to transmit data through the water.                    (greater than 190
                                                        dB).
Synthetic Aperture Sonars (SAS):     SAS2              HF SAS systems.......        H         1,312        9,184
 Sonars in which active acoustic
 signals are post-processed to form
 high-resolution images of the
 seafloor.
Broadband Sound Sources (BB): Sonar  BB1               MF to HF mine                H            48          336
 systems with large frequency                           countermeasure sonar.
 spectra, used for various purposes.
                                     BB2               HF to VHF mine               H            48          336
                                                        countermeasure sonar.
----------------------------------------------------------------------------------------------------------------
Notes: H = hours; C = count.

    Table 7 describes the explosive source classes and numbers that 
could occur over seven years under the proposed training activities. 
Under the proposed activities bin use would vary annually, and the 
seven-year totals for the proposed training activities take into 
account that annual variability.

 Table 7--Explosive Source Class Bins Analyzed and Numbers Used for Seven-Year Period for Training Activities in
                                               the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                         Net explosive
                  Bin                    weight  (lb)   Example explosive source      Annual       7-Year total
----------------------------------------------------------------------------------------------------------------
E1....................................        0.1-0.25  Medium-caliber                    60-120             672
                                                         projectiles.
E2....................................       >0.25-0.5  Medium-caliber                    65-130             728
                                                         projectiles.
E3....................................        >0.5-2.5  Explosive Ordnance                     6              42
                                                         Disposal Mine
                                                         Neutralization.
E5....................................           >5-10  Large-caliber projectile          56-112             628
E10...................................        >250-500  1,000 lb bomb...........             0-4               9
----------------------------------------------------------------------------------------------------------------
Notes: (1) Net explosive weight refers to the equivalent amount of TNT. The actual weight of a munition may be
  larger due to other components. lb = pound(s), ft = feet.

    Table 8 describes the explosive source classes and numbers that 
could occur over seven years under the proposed testing activities. 
Under the proposed activities bin use would vary annually, and the 
seven-year totals for the proposed testing activities take into account 
that annual variability.

 Table 8--Explosive Source Class Bins Analyzed and Numbers Used for Seven-Year Period for Testing Activities in
                                               the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                         Net explosive
                  Bin                    weight  (lb)   Example explosive source      Annual       7-Year total
----------------------------------------------------------------------------------------------------------------
E1....................................        0.1-0.25  SUS buoy................               8              56
E3....................................        >0.5-2.5  Explosive sonobuoy......              72             504
E4....................................          >2.5-5  Mine Countermeasure and               36             180
                                                         Neutralization.
E7....................................          >20-60  Mine Countermeasure and                5              25
                                                         Neutralization.
E8....................................         >60-100  Lightweight torpedo.....               4              28
E11...................................        >500-650  Heavyweight torpedo.....               4              28
----------------------------------------------------------------------------------------------------------------
Notes: (1) Net explosive weight refers to the equivalent amount of TNT. The actual weight of a munition may be
  larger due to other components. lb = pound(s), ft = feet.


[[Page 33929]]

Vessel Movement

    Vessels used as part of the proposed activities include ships, 
submarines, unmanned vessels, and boats ranging in size from small, 22 
ft rigid hull inflatable boats to aircraft carriers with lengths up to 
1,092 ft. Large ships greater than 60 ft generally operate at speeds in 
the range of 10-15 kn for fuel conservation. Submarines generally 
operate at speeds in the range of 8-13 kn in transits and less than 
those speeds for certain tactical maneuvers. Small craft (for purposes 
of this discussion--less than 60 ft in length) have much more variable 
speeds (dependent on the mission). While these speeds are 
representative of most events, some vessels 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. 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 will be dead in the water or moving slowly ahead to maintain 
steerage.
    The number of military vessels used in the NWTT Study Area varies 
based on military training and testing requirements, deployment 
schedules, annual budgets, and other unpredictable factors. Many 
training and testing activities involve the use of vessels. These 
activities could be widely dispersed throughout the NWTT Study Area, 
but would be typically conducted near naval ports, piers, and range 
areas. Training and testing activities involving vessel movements occur 
intermittently and are variable in duration, ranging from a few hours 
to up to two weeks. There is no seasonal differentiation in military 
vessel use. Large vessel movement primarily occurs with the majority of 
the traffic flowing between the installations and the Operating Areas 
(OPAREAS). Smaller support craft would be more concentrated in the 
coastal waters in the areas of naval installations, ports, and ranges. 
The number of activities that include the use of vessels for training 
events is lower (approximately 10 percent) than the number for testing 
activities. Testing can occur jointly with a training event, in which 
case that testing activity could be conducted from a training vessel.
    Additionally, a variety of smaller craft will be operated within 
the NWTT Study Area. Small craft types, sizes, and speeds vary. During 
training and testing, speeds generally range from 10-14 kn; however, 
vessels can and will, on occasion, operate within the entire spectrum 
of their specific operational capabilities. In all cases, the vessels/
craft will be operated in a safe manner consistent with the local 
conditions.

Standard Operating Procedures

    For training and testing to be effective, personnel must be able to 
safely use their sensors and weapon systems as they are intended to be 
used in military missions and combat operations and to their optimum 
capabilities. 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 benefits to 
environmental, socioeconomic, public health and safety, and cultural 
resources.
    Navy standard operating procedures have been developed and refined 
over years of experience and are broadcast via numerous naval 
instructions and manuals, including, but not limited to the following 
materials:
     Ship, submarine, and aircraft safety manuals;
     Ship, submarine, and aircraft standard operating manuals;
     Fleet Area Control and Surveillance Facility range 
operating instructions;
     Fleet exercise publications and instructions;
     Naval Sea Systems Command test range safety and standard 
operating instructions;
     Navy-instrumented range operating procedures;
     Naval shipyard sea trial agendas;
     Research, development, test, and evaluation plans;
     Naval gunfire safety instructions;
     Navy planned maintenance system instructions and 
requirements;
     Federal Aviation Administration regulations; and
     International Regulations for Preventing Collisions at 
Sea.
    Because standard operating procedures are essential to safety and 
mission success, the Navy considers them to be part of the proposed 
Specified Activities, and has included them in the environmental 
analysis. Standard operating procedures that are recognized as having a 
potential benefit to marine mammals during training and testing 
activities are noted below and discussed in more detail within the 2019 
NWTT DSEIS/OEIS.
     Vessel Safety;
     Weapons Firing Procedures;
     Target Deployment Safety; and
     Towed In-Water Device Safety.
    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 
environmental impacts). Information on mitigation measures is provided 
in the Proposed Mitigation section below. Additional information on 
standard operating procedures is presented in Section 2.3.3 (Standard 
Operating Procedures) in the 2019 NWTT DSEIS/OEIS.

Description of Marine Mammals and Their Habitat in the Area of the 
Specified Activities

    Marine mammal species and their associated stocks that have the 
potential to occur in the NWTT Study Area are presented in Table 9 
along with an abundance estimate, an associated coefficient of 
variation value, and best and minimum abundance estimates. The Navy 
requests authorization to take individuals of 29 marine mammal species 
by Level A harassment and Level B harassment incidental to training and 
testing activities from the use of sonar and other transducers and in-
water detonations. In addition, the Navy requests authorization for 
three takes of large whales by serious injury or mortality from vessel 
strikes over the seven-year period. Currently, the Southern Resident 
killer whale has critical habitat designated under the Endangered 
Species Act (ESA) in the NWTT Study Area (described below). However, 
NMFS has recently published two proposed rules, proposing new or 
revised ESA-designated critical habitat for humpback whales (84 FR 
54354; October 9, 2019) and Southern Resident killer whales (84 FR 
49214; September 19, 2019).
    Information on the status, distribution, abundance, population 
trends, habitat, and ecology of marine mammals in the NWTT Study Area 
may be found in Chapter 4 of the Navy's rulemaking/LOA application. 
NMFS has reviewed this information and found it to be accurate and 
complete. Additional information on the general biology and ecology of 
marine mammals is included in the 2019 NWTT DSEIS/OEIS. Table 9 
incorporates data from the U.S. Pacific and the Alaska Marine Mammal 
Stock Assessment Reports (SARs; Carretta et al., 2019; Muto et al., 
2019) and the most recent revised data in the draft SARs (see https://www.fisheries.noaa .gov/national/marine-mammal-protection/draft-marine-
mammal-stock-assessment-reports); as well as incorporates the best 
available science, including monitoring data from the Navy's marine 
mammal research efforts.

[[Page 33930]]

Species Not Included in the Analysis

    The species carried forward for analysis (and described in Table 9 
below) are those likely to be found in the NWTT 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). Several species that 
may be present in the northwest Pacific Ocean have an extremely low 
probability of presence in the NWTT Study Area. These species are 
considered extralimital (not anticipated to occur in the Study Area) or 
rare (occur in the Study Area sporadically, but sightings are rare). 
These species/stocks include the Eastern North Pacific stock of Bryde's 
whale (Balaenoptera edeni), Eastern North Pacific stock of North 
Pacific right whale (Eubalaena japonica), false killer whale (Pseudorca 
crassidens), long-beaked common dolphin (Delphinus capensis), Western 
U.S. stock of Steller sea lion (Eumetopias jubatus), and Alaska stock 
of Cuvier's beaked whale (Ziphius cavirostris). Despite rare stranding 
or sighting reports, the Study Area is outside the normal range of the 
Eastern North Pacific stock of Bryde's whale and the California stock 
of the long-beaked common dolphin. The Study Area is also outside the 
normal range of the false killer whale's distribution in the Pacific 
Ocean. The Eastern North Pacific stock of North Pacific right whale is 
estimated to have an abundance of 31 individuals (Muto et al., 2020) 
and is anticipated to be extremely rare in the Study Area. The Western 
U.S. stock of Steller sea lions is considered rare in the Offshore Area 
of the Study Area, and is not expected to occur in the Inland Waters 
portion of the Study Area. In Western Behm Canal, there is a low 
probability of juvenile male Steller sea lion occurrence from the 
Western U.S. stock, however these individuals are anticipated to be 
very rare. Finally, the Alaska stock of Cuvier's beaked whales is not 
expected to occur in either the Offshore Area or Inland Waters of the 
NWTT Study Area, and are considered extralimital in Western Behm Canal 
as this area does not overlap with their range of distribution. NMFS 
agrees with the Navy's assessment that these species are unlikely to 
occur in the NWTT Study Area and they are not discussed further.

                                              Table 9--Marine Mammal Occurrence Within the NWTT Study Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    ESA/MMPA    Stock abundance                                  Occurrence
                                                                     status;   (CV, Nmin,  most            Annual --------------------------------------
         Common name            Scientific name        Stock        strategic  recent abundance    PBR     M/SI 3
                                                                     (Y/N) 1       survey) 2                         Offshore      Inland      Western
                                                                                                                       area        waters     Behm Canal
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray whale...............  Eschrichtius      Eastern North     -, -, N     26.960 (0.05,         801      139  Seasonal...  Seasonal...  ...........
                                robustus.         Pacific.                      25,849, 2016).
Family Balaenopteridae
 (rorquals):
    Blue whale...............  Balaenoptera      Eastern North     E, D, S     1,496 (0.44,          1.2   >=19.4  Seasonal...
                                musculus.         Pacific.                      1,050, 2014).
    Fin whale................  Balaenoptera      Northeast         E, D, S     3,168 (0.26,          5.1      0.4                            Rare.
                                physalus.         Pacific.                      2,554, 2013)
                                                                                \4\.
                                                 CA/OR/WA........  E, D, S     9,029 (0.12,           81   >=43.5  Seasonal...  Rare.......  ...........
                                                                                8,127, 2014).
    Humpback whale...........  Megaptera         Central North     T/E,\5\ D,  10,103 (0.3,           83       25  Regular....  Regular....  Regular.
                                novaeangliae.     Pacific.          S           7,891, 2006).
                                                 CA/OR/WA........  T/E,\5\ D,  2,900 (0.05,         16.7   >=42.1  Regular....  Regular....  Regular.
                                                                    S           2,784, 2014).
    Minke whale..............  Balaenoptera      Alaska..........  -, -, N     UNK.............      UND        0                            Rare.
                                acutorostrata.
                                                 CA/OR/WA........  -, -, N     636 (0.72, 369,       3.5    >=1.3  Regular....  Seasonal...
                                                                                2014).
    Sei whale................  Balaenoptera      Eastern North     E, D, S     519 (0.4, 374,       0.75    >=0.2  Regular....  ...........  ...........
                                borealis.         Pacific.                      2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale..............  Physeter          CA/OR/WA........  E, D, S     1.997 (0.57,          2.5      0.4  Rare.......
                                macrocephalus.                                  1,270, 2014).
Family Kogiidae:
    Dwarf sperm whale........  Kogia sima......  CA/OR/WA........  -, -, N     UNK.............      UND        0  Rare.......
    Pygmy sperm whale........  Kogia breviceps.  CA/OR/WA........  -, -, N     4,111 (1.12,         19.2        0  Regular....
                                                                                1,924, 2014).
Family Ziphiidae (beaked
 whales):
    Baird's beaked whale.....  Berardius         CA/OR/WA........  -, -, N     2,697 (0.6,            16        0  Regular....
                                bairdii.                                        1,633, 2014).
    Cuvier's beaked whale....  Ziphius           CA/OR/WA........  -, -, N     3,274 (0.67,           21    < 0.1  Regular....
                                cavirostris.                                    2,059, 2014).
3Mesoplodont beaked whales...  Mesoplodon        CA/OR/WA........  -, -, N     3,044 (0.54,           20      0.1  Regular....
                                species.                                        1,967, 2014).
Family Delphinidae:
    Common bottlenose dolphin  Tursiops          CA/OR/WA          -, -, N     1,924 (0.54,           11    >=1.6  Regular....
                                truncatus.        Offshore.                     1,255, 2014).
    Killer whale.............  Orcinus orca....  Eastern North     -, -, N     2,347 (UNK,            24        1                            Regular.
                                                  Pacific Alaskan               2,347, 2012)
                                                  Resident.                     \6\.
                                                 Eastern North     -, -, N     302 (UNK, 302,        2.2      0.2  Seasonal...  Seasonal...  ...........
                                                  Pacific                       2018) \6\.
                                                  Northern
                                                  Resident.
                                                 West Coast        -, -, N     243 (UNK, 243,        2.4        0  Regular....  Regular....  Regular.
                                                  Transient.                    2009).
                                                 Eastern North     -, -, N     300 (0.1, 276,        2.8        0  Regular....               Regular.
                                                  Pacific                       2012).
                                                  Offshore.
                                                 Eastern North     E, D, Y     75 (NA, 75,          0.13        0  Seasonal...  Regular....  ...........
                                                  Pacific                       2018).
                                                  Southern
                                                  Resident.
    Northern right whale       Lissodelphus      CA/OR/WA........  -, -, N     26,556 (0.44,         179      3.8  Regular....
     dolphin.                   borealis.                                       18,608, 2014).
    Pacific white-sided        Lagenorhynchus    North Pacific...  -, -, N     26,880 (UNK, NA,      UND        0                            Regular.
     dolphin.                   obliquidens.                                    1990).
                                                 CA/OR/WA........  -, -, N     26,814 (0.28,         191      7.5  Regular....  Regular....  ...........
                                                                                21,195, 2014).
    Risso's dolphin..........  Grampus griseus.  CA/OR/WA........  -, -, N     6,336 (0.32,           46    >=3.7  Regular....  Rare.......  ...........
                                                                                4,817, 2014).
    Short-beaked common        Delphinus         CA/OR/WA........  -, -, N     969,861 (0.17,      8,393  [egr]40  Regular....  Rare.......  ...........
     dolphin.                   delphis.                                        839,325, 2014).
    Short-finned pilot whale.  Globicephala      CA/OR/WA........  -, -, N     836 (0.79, 466,       4.5      1.2  Regular....  Rare.......  ...........
                                macrorhynchus.                                  2014).
    Striped dolphin..........  Stenella          CA/OR/WA........  -, -, N     29,211 (0.2,          238    >=0.8  Regular....
                                coeruleoalba.                                   24,782, 2014).
Family Phocoenidae
 (porpoises):
    Dall's porpoise..........  Phocoenoides      Alaska..........  -, -, N     83,400 (0.097,        UND       38                            Regular.
                                dalli.                                          NA, 1991).

[[Page 33931]]

 
                                                 CA/OR/WA........  -, -, N     25,750 (0.45,         172      0.3  Regular....  Regular....  ...........
                                                                                17,954, 2014).
    Harbor porpoise..........  Phocoena          Southeast Alaska  -, -, Y     1,354 (0.12,           12       34                            Regular.
                                phocoena.                                       1,224, 2012).
                                                 Northern OR/WA    -, -, N     21,487 (0.44,         151      >=3  Regular....
                                                  Coast.                        15, 123, 2011).
                                                 Northern CA/      -, -, N     35,769 (0.52,         475    >=0.6  Regular....
                                                  Southern OR.                  23,749, 2011).
                                                 Washington        -, -, N     11,233 (0.37,          66    >=7.2               Regular....  ...........
                                                  Inland Waters.                8,308, 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals
 and sea lions):
    California sea lion......  Zalophus          U.S.............  -, -, N     257,606 (NA,       14,011    >=321  Seasonal...  Regular....  ...........
                                californianus.                                  233,515, 2014).
    Guadalupe fur seal.......  Arctocephalus     Mexico to         T, D, Y     34,187 (NA,         1,062    >=3.8  Seasonal...
                                townsendi.        California.                   31,109, 2013).
    Northern fur seal........  Callorhinus       Eastern Pacific.  -, D, Y     620,660 (0.2,      11,295      399  Regular....               Seasonal.
                                ursinus.                                        525,333, 2016).
                                                 California......  -, -, N     14,050 (NA,           451      1.8  Regular....
                                                                                7,524, 2013).
    Steller sea lion.........  Eumetopias        Eastern U.S.....  -, -, N     43,201 (NA,         2,592      113  Regular....  Seasonal...  Regular.
                                jubatus.                                        43,201, 2017)
                                                                                \7\.
Family Phocidae (earless
 seals):
    Harbor seal..............  Phoca vitulina..  Southeast Alaska  -, -, N     27,659 (UNK,          746       40                            Regular.
                                                  (Clarence                     24,854, 2015).
                                                  Strait).
                                                 OR/WA Coast.....  -, -, N     UNK.............      UND     10.6  Regular....  Seasonal...  ...........
                                                 California......  -, -, N     30,968 (0.157,      1,641       43  Regular....
                                                                                27,348, 2012).
                                                 Washington        -, -, N     UNK.............      UND      9.8  Seasonal...  Regular....  ...........
                                                  Northern Inland
                                                  Waters.
                                                 Hood Canal......  -, -, N     UNK.............      UND      0.2  Seasonal...  Regular....  ...........
                                                 Southern Puget    -, -, N     UNK.............      UND      3.4  Seasonal...  Regular....  ...........
                                                  Sound.
    Northern Elephant seal...  Mirounga          California......  -, -, N     179,000 (NA,        4,882      8.8  Regular....  Regular....  Seasonal.
                                angustirostris.                                 81,368, 2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 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 potential biological removal (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.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-
  assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For the Eastern
  North Pacific Southern Resident stock of killer whales Nbest/Nmin are based on a direct count of individually identifiable animals. The population
  size of the U.S. stock of California sea lion was estimated from a 1975-2014 time series of pup counts (Lowry et al. 2017), combined with mark-
  recapture estimates of survival rates (DeLong et al. 2017, Laake et al. 2018). The population size of the Mexico to California stock of Guadalupe fur
  seals was estimated from pup count data collected in 2013 and a range of correction factors applied to pup counts to account for uncounted age classes
  and pre-census pup mortality (Garc[iacute]a-Aguilar et al. 2018). The population size of the California stock of Northern fur seals was estimated from
  pup counts multiplied by an expansion factor (San Miguel Island) and maximum pup, juvenile, and adult counts (Farrallon Islands) at rookeries. The
  population size of the Eastern U.S. stock of Steller sea lions was estimated from pup counts and non-pup counts at rookeries in Southeast Alaska,
  British Columbia, Oregon, and California. The population size of the California stock of Northern Elephant seals was estimated from pup counts at
  rookeries multiplied by the inverse of the expected ratio of pups to total animals (McCann, 1985; Lowry et al., 2014).
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality and serious injury (M/SI) 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.
\4\ SAR reports this stock abundance assessment as provisional and notes that it is an underestimate for the entire stock because it is based on surveys
  which covered only a small portion of the stock's range.
\5\ Humpback whales in the Central North Pacific stock and the CA/OR/WA stock are from three Distinct Population Segments (DPSs) based on animals
  identified in breeding areas in Hawaii, Mexico, and Central America. Both stocks and all three DPSs co-occur in the NWTT Study Area.
\6\ Stock abundance estimate is based on counts of individual animals identified from photo-identification catalogues. Surveys for abundance estimates
  of these stocks are conducted infrequently.
\7\ Stock abundance estimate is the best estimate counts, which have not been corrected to account for animals at sea during abundance surveys.
Note--Unknown (UNK); Undetermined (UND); Not Applicable (NA); California (CA); Oregon (OR); Washington (WA).

    Below, we include 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 (UME) have been designated.

Critical Habitat

    Currently, only the distinct population segment (DPS) of Southern 
Resident killer whale (SRKW) has ESA-designated critical habitat in the 
NWTT Study Area. NMFS has recently published two proposed rules, 
however, proposing new or revised ESA-designated critical habitat for 
SRKW (84 FR 49214; September 19, 2019) and humpback whales (84 FR 
54354; October 9, 2019).
    NMFS designated critical habitat for the SRKW DPS on November 29, 
2006 (71 FR 69054) in inland waters of Washington State. Based on the 
natural history of the SRKWs and their habitat needs, NMFS identified 
physical or biological features essential to the conservation of the 
SRKW 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. ESA-designated critical habitat consists of 
three areas: (1) The Summer Core Area in Haro Strait and waters around 
the San Juan Islands; (2) Puget Sound; and (3) the Strait of Juan de 
Fuca, which comprise approximately 2,560 square miles (mi\2\) (6,630 
square kilometers (km\2\)) of marine habitat. In designating critical 
habitat, NMFS considered economic impacts and impacts to national 
security, and concluded the benefits of exclusion of 18 military sites, 
comprising approximately 112 mi\2\ (291 km\2\), outweighed the benefits 
of inclusion because of national security impacts.
    On January 21, 2014, NMFS received a petition requesting revisions 
to the SRKW critical habitat designation. The petition requested NMFS 
revise critical habitat to include ``inhabited marine waters along the 
West Coast of the United States that constitute essential foraging and 
wintering areas,'' specifically the region between Cape Flattery, 
Washington and Point Reyes, California extending from the coast to a 
distance of 47.2 mi (76 km) offshore.

[[Page 33932]]

The petition also requested NMFS adopt a fourth essential habitat 
feature in both current and expanded critical habitat relating to in-
water sound levels. On September 19, 2019 (84 FR 54354), NMFS published 
a proposed rule proposing to revise the critical habitat designation 
for the SRKW DPS by designating six new areas (using the same essential 
features determined in 2006) along the U.S. West Coast. Specific new 
areas proposed along the U.S. West Coast include 15,626.6 mi\2\ 
(40,472.7 km\2\) of marine waters between the 6.1 m (20 ft) depth 
contour and the 200 m (656.2 ft) depth contour from the U.S. 
international border with Canada south to Point Sur, California.
    On March 15, 2018, several non-governmental organizations filed a 
lawsuit seeking court-ordered deadlines for the issuance of proposed 
and final rules to designate ESA critical habitat for the Central 
American, Mexico, and Western North Pacific DPSs of humpback whales. In 
2018, NMFS convened a critical habitat review team to assess and 
evaluate information in support of critical habitat designation for 
these DPSs. On October 9, 2019 (84 FR 54354), NMFS published a proposed 
rule proposing ESA-designated critical habitat areas located off the 
coasts of California, Oregon, Washington, and Alaska, including areas 
within the NWTT Study Area. Based on consideration of national security 
and economic impacts, NMFS also proposed to exclude multiple areas from 
the designation for each DPS.

Biologically Important Areas

    Biologically Important Areas (BIAs) include areas of known 
importance for reproduction, feeding, or migration, or areas where 
small and resident populations are known to occur (Van Parijs, 2015). 
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 may be found here: https://cetsound.noaa.gov/biologically-important-area-map.
    BIAs off the West Coast of the continental United States with the 
potential to overlap portions of the NWTT Study Area include the 
following feeding and migration areas: Northern Puget Sound Feeding 
Area for gray whales (March-May); Northwest Feeding Area for gray 
whales (May-November); Northbound Migration Phase A for gray whales 
(January-July); Northbound Migration Phase B for gray whales (March-
July); Northern Washington Feeding Area for humpback whales (May-
November); Stonewall and Heceta Bank Feeding Area for humpback whales 
(May-November); and Point St. George Feeding Area for humpback whales 
(July-November) (Calambokidis et al., 2015).
    When comparing the geographic area of the NWTT Study Area with the 
BIAs off the West Coast of the continental United States, there is no 
direct spatial overlap between the Study Area and four of the offshore 
gray whale feeding areas--Grays Harbor, WA; Depoe Bay, OR; Cape Blanco 
and Orford Reef, OR; and Pt. St. George, CA. The NWTT Study Area does 
overlap with the Northwest WA gray whale feeding area and the Northern 
Puget Sound gray whale feeding area. There is no overlap of the gray 
whale migration corridor BIAs and the NWTT Study Area, with the 
exception of a portion of the Northwest coast of Washington 
approximately from Pacific Beach and extending north to the Strait of 
Juan de Fuca. The offshore Northern WA humpback whale feeding area is 
located entirely within the NWTT Study Area boundaries. The humpback 
whale feeding area at Stonewall and Hecta Bank only partially overlaps 
with the Study Area, and the feeding area at Point St. George has 
extremely limited overlap with the Study Area. All proposed activities 
occurring in the Offshore Area of the Study Area could potentially 
occur in these BIAs, except activities limited to greater than 50 nmi 
from shore (as described in the Proposed Mitigation Measures section). 
To mitigate impacts to marine mammals in these BIAs, the Navy would 
implement several procedural mitigation measures and mitigation areas 
(described in the Proposed Mitigation Measures section).

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 or regulate 
activities that could destroy, cause the loss of, or injure sanctuary 
resources pursuant to the regulations for that sanctuary and other 
applicable law (15 CFR part 922). NMSs 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 whenever their activities are likely to 
destroy, cause the loss of, or injure a sanctuary resource. One NMS, 
the Olympic Coast NMS managed by the Office of National Marine 
Sanctuaries, is located within the offshore portion of the NWTT Study 
Area (for a map of the location of this NMS see Chapter 6 of the 2019 
NWTT DSEIS/OEIS and Figure 6-1).
    The Olympic Coast NMS includes 3,188 mi\2\ of marine waters and 
submerged lands off the Olympic Peninsula coastline. The sanctuary 
extends 25-50 mi. (40.2-80.5 km) seaward, covering much of the 
continental shelf and portions of three major submarine canyons. The 
boundaries of the sanctuary as defined in the Olympic Coast NMS 
regulations (15 CFR part 922, subpart O) extend from Koitlah Point, due 
north to the United States/Canada international boundary, and seaward 
to the 100-fathom isobath (approximately 180 m in depth). The seaward 
boundary of the sanctuary follows the 100-fathom isobath south to a 
point due west of Copalis River, and cuts across the tops of Nitinat, 
Juan de Fuca, and the Quinault Canyons. The shoreward boundary of the 
sanctuary is at the mean lower low-water line when adjacent to American 
Indian lands and state lands, and includes the intertidal areas to the 
mean higher high-water line when adjacent to federally managed lands. 
When adjacent to rivers and streams, the sanctuary boundary cuts across 
the mouths but does not extend up river or up stream. The Olympic Coast 
NMS includes many types of productive marine habitats including kelp 
forests, subtidal reefs, rocky and sand intertidal zones, submarine 
canyons, rocky deep-sea habitat, and plankton-rich upwelling zones. 
These habitats support the Sanctuary's rich biodiversity which includes 
29 species of marine mammals that reside in or migrate through the 
Sanctuary (Office of National Marine Sanctuaries 2008). Additional 
information on the Olympic Coast NMS can be found at https://olympiccoast.noaa.gov.

Unusual Mortality Events (UMEs)

    An UME is defined under Section 410(6) of the MMPA as a stranding 
that is unexpected; involves a significant die-off of any marine mammal 
population; and demands immediate response. Three UMEs with ongoing 
investigations in the NWTT Study Area that inform our analysis are 
discussed below. The California sea lion UME in

[[Page 33933]]

California is still open, but will be closed soon. The Guadalupe fur 
seal UME in California and the gray whale UME along the west coast of 
North America are active and involve ongoing investigations.
California Sea Lion UME
    From January 2013 through September 2016, a greater than expected 
number of young malnourished California sea lions (Zalophus 
californianus) stranded along the coast of California. Sea lions 
stranding from an early age (6-8 months old) through two years of age 
(hereafter referred to as juveniles) were consistently underweight 
without other disease processes detected. Of the 8,122 stranded 
juveniles attributed to the UME, 93 percent stranded alive (n = 7,587, 
with 3,418 of these released after rehabilitation) and 7 percent (n = 
531) stranded dead. Several factors are hypothesized to have impacted 
the ability of nursing females and young sea lions to acquire adequate 
nutrition for successful pup rearing and juvenile growth. In late 2012, 
decreased anchovy and sardine recruitment (CalCOFI data, July 2013) may 
have led to nutritionally stressed adult females. Biotoxins were 
present at various times throughout the UME, and while they were not 
detected in the stranded juvenile sea lions (whose stomachs were empty 
at the time of stranding), biotoxins may have impacted the adult 
females' ability to support their dependent pups by affecting their 
cognitive function (e.g., navigation, behavior towards their 
offspring). Therefore, the role of biotoxins in this UME, via its 
possible impact on adult females' ability to support their pups, is 
unclear. The proposed primary cause of the UME was malnutrition of sea 
lion pups and yearlings due to ecological factors. These factors 
included shifts in distribution, abundance and/or quality of sea lion 
prey items around the Channel Island rookeries during critical sea lion 
life history events (nursing by adult females, and transitioning from 
milk to prey by young sea lions). These prey shifts were most likely 
driven by unusual oceanographic conditions at the time due to the 
``Warm Water Blob'' and El Ni[ntilde]o. This investigation will soon be 
closed. Please refer to: https://www.fisheries.noaa.gov/national/
marine-life-distress/2013-2017-california-sea-lion-unusual-mortality-
event-california for more information on this UME.
Guadalupe Fur Seal UME
    Increased strandings of Guadalupe fur seals began along the entire 
coast of California in January 2015 and were eight times higher than 
the historical average (approximately 10 seals/yr). Strandings have 
continued since 2015 and remained well above average through 2019. 
Numbers by year are as follows: 2015 (98), 2016 (76), 2017 (62), 2018 
(45), 2019 (116), 2020 (3 as of March 6, 2020). The total number of 
Guadalupe fur seals stranding in California from January 1, 2015, 
through March 6, 2020, in the UME is 400. Additionally, strandings of 
Guadalupe fur seals became elevated in the spring of 2019 in Washington 
and Oregon; subsequently, strandings for seals in these two states have 
been added to the UME starting from January 1, 2019. The current total 
number of strandings in Washington and Oregon is 94 seals, including 91 
in 2019 and 3 in 2020 of 3/6/2020. Strandings are seasonal and 
generally peak in April through June of each year. The Guadalupe fur 
seal strandings have been mostly weaned pups and juveniles (1-2 years 
old) with both live and dead strandings occurring. Current findings 
from the majority of stranded animals include primary malnutrition with 
secondary bacterial and parasitic infections. The California portion of 
this UME was occurring in the same area as the 2013-2016 California sea 
lion UME. This investigation is ongoing. Please refer to: https://www.fisheries.noaa.gov/national/marine-life-distress/2015-2019-
guadalupe-fur-seal-unusual-mortality-event-california for more 
information on this UME.
Gray Whale UME
    Since January 1, 2019, elevated gray whale strandings have occurred 
along the west coast of North America, from Mexico to Canada. As of 
March 13, 2020, there have been a total of 264 strandings along the 
coasts of the United States, Canada, and Mexico, with 129 of those 
strandings occurring along the U.S. coast. Of the strandings on the 
U.S. coast, 48 have occurred in Alaska, 35 in Washington, 6 in Oregon, 
and 40 in California. Partial necropsy examinations conducted on a 
subset of stranded whales have shown evidence of poor to thin body 
condition. As part of the UME investigation process, NOAA is assembling 
an independent team of scientists to coordinate with the Working Group 
on Marine Mammal Unusual Mortality Events to review the data collected, 
sample stranded whales, and determine the next steps for the 
investigation. Please refer to: https://www.fisheries.noaa.gov/
national/marine-life-distress/2019-gray-whale-unusual-mortality-event-
along-west-coast for more information on this UME.

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. Current data indicate that 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) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 dB 
threshold from the normalized composite audiograms, with the exception 
for lower limits for low-frequency cetaceans where the lower bound was 
deemed to be biologically implausible and the lower bound from Southall 
et al. (2007) retained. The functional groups and the associated 
frequencies are indicated below (note that these frequency ranges 
correspond to the range for the composite group, with the entire range 
not necessarily reflecting the capabilities of every species within 
that group):
     Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 Hz and 35 kHz;
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members of the genera Kogia and Cephalorhynchus; including two members 
of the genus Lagenorhynchus, on the basis of recent echolocation data 
and genetic data): Generalized hearing is estimated to occur between 
approximately 275 Hz and 160 kHz;
     Pinnipeds in water; Phocidae (true seals): Generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kHz; 
and

[[Page 33934]]

     Pinnipeds in water; Otariidae (eared seals): Generalized 
hearing is estimated to occur between 60 Hz and 39 kHz.
    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more details concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of the available 
information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a discussion of the ways that components of 
the specified activity may impact marine mammals and their habitat. The 
Estimated Take of Marine Mammals section later in this rule includes a 
quantitative analysis of the number of instances of take that could 
occur from these activities. 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 through effects on annual rates of 
recruitment or survival.
    The Navy has requested authorization for the take of marine mammals 
that may occur incidental to training and testing activities in the 
NWTT Study Area. The Navy analyzed potential impacts to marine mammals 
from acoustic and explosive sources and from vessel use in its 
rulemaking/LOA application. NMFS carefully reviewed the information 
provided by the Navy along with independently reviewing applicable 
scientific research and literature and other information to evaluate 
the potential effects of the Navy's activities on marine mammals, which 
are presented in this section.
    Other potential impacts to marine mammals from training and testing 
activities in the NWTT Study Area were analyzed in the 2019 NWTT DSEIS/
OEIS, in consultation with NMFS as a cooperating agency, and determined 
to be unlikely to result in marine mammal take. This includes serious 
injury or mortality from explosives. Therefore, the Navy has 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 cause the take of marine mammals: 
Exposure to acoustic or explosive stressors including non-impulsive 
(sonar and other transducers) and impulsive (explosives) 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 (permanent threshold shift 
(PTS) and 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 trauma, 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 from 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 rise to the 
level of a take. 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

    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, non-auditory physical or 
physiological effects, behavioral disturbance, stress, and masking 
(Richardson et al., 1995; Gordon et al., 2004; 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 
hearing loss, 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. 
Note that in the following discussion, we refer in many cases to a 
review article concerning studies of noise-induced hearing loss 
conducted from 1996-2015 (i.e., Finneran, 2015). For study-specific 
citations, please see that work. We first describe general 
manifestations of acoustic effects before providing discussion specific 
to the Navy's activities.
    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 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

[[Page 33935]]

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 
mortality (Yelverton et al., 1973). Non-auditory physiological effects 
or injuries that theoretically might occur in marine mammals exposed to 
high level underwater sound or as a secondary effect of extreme 
behavioral reactions (e.g., change in dive profile as a result of an 
avoidance reaction) 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).

Acoustic Sources

Direct Physiological Effects
    Non-impulsive sources of sound can cause direct physiological 
effects including noise-induced loss of hearing sensitivity (or 
``threshold shift''), nitrogen decompression, acoustically-induced 
bubble growth, and injury due to sound-induced acoustic resonance. Only 
noise-induced hearing loss is anticipated to occur due to the Navy's 
activities. Acoustically-induced (or mediated) bubble growth and other 
pressure-related physiological impacts are addressed briefly below, but 
are not expected to result from the Navy's activities. Separately, an 
animal's behavioral reaction to an acoustic exposure might lead to 
physiological effects that might ultimately lead to injury or death, 
which is discussed later in the Stranding subsection.

Hearing Loss--Threshold Shift

    Marine mammals exposed to high-intensity sound, or to lower-
intensity sound for prolonged periods, can experience hearing threshold 
shift, which is the loss of hearing sensitivity at certain frequency 
ranges after cessation of sound (Finneran, 2015). Threshold shift can 
be permanent (PTS), in which case the loss of hearing sensitivity is 
not fully recoverable, or temporary (TTS), in which case the animal's 
hearing threshold would recover over time (Southall et al., 2007). TTS 
can last from minutes or hours to days (i.e., there is recovery back to 
baseline/pre-exposure levels), 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 auditory injury 
(e.g., neural degeneration), as TTS increases, the likelihood that 
additional exposure sound pressure level (SPL) or duration will result 
in PTS or other injury also increases (see also the 2019 NWTT DSEIS/
OEIS for additional discussion). Exposure thresholds for the occurrence 
of PTS or other auditory injury 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 PTS or other injury. The specific upper limit of TTS is based on 
experimental data showing amounts of TTS that have not resulted in PTS 
or injury. In other words, we do not need to know the exact functional 
relationship between TTS and PTS or other injury, we only need to know 
the upper limit for TTS before some PTS or injury is possible. In 
severe cases of PTS, 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).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). PTS 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 TTS to constitute 
auditory injury.
    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 sound exposure 
level (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). However, some more recent 
studies concluded that for all noise exposure situations the equal 
energy relationship may not be the best indicator to predict TTS onset 
levels (Mooney et al., 2009a and 2009b; Kastak et al., 2007). 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, with sound 
exposures of equal energy, those that were quieter (lower SPL) with 
longer duration were found to induce TTS onset at lower levels than 
those of louder (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). For example, one short but loud (higher 
SPL) sound exposure may induce the same impairment as one longer but 
softer (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 PTS, at least in terrestrial mammals (Kryter, 1985; Lonsbury-
Martin et al., 1987).
    PTS is considered auditory injury (Southall et al., 2007). 
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).
    The NMFS Acoustic Technical Guidance (NMFS, 2018), which was used 
in the assessment of effects for this rule, compiled, interpreted, and

[[Page 33936]]

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. More recently, 
Southall et al. (2019a) evaluated Southall et al. (2007) and used 
updated scientific information to propose revised noise exposure 
criteria to predict onset of auditory effects in marine mammals (i.e., 
PTS and TTS onset). Southall et al. (2019a) note that the quantitative 
processes described and the resulting exposure criteria (i.e., 
thresholds and auditory weighting functions) are largely identical to 
those in Finneran (2016) and NMFS (2018). They only differ in that the 
Southall et al. (2019a) exposure criteria are more broadly applicable 
as they include all marine mammal species (rather than only those under 
NMFS jurisdiction) for all noise exposures (both in air and underwater 
for amphibious species) and, while the hearing group compositions are 
identical, they renamed the hearing groups.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019a) for 
summaries), however for cetaceans, published data on the onset of TTS 
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, and California sea 
lions. These studies examine hearing thresholds measured in marine 
mammals before and after exposure to intense sounds. The difference 
between the pre-exposure and post-exposure thresholds 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 2019 NWTT DSEIS/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.
     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 low frequencies, 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 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 
(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 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

[[Page 33937]]

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 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 PTS on 
an animal could also range in severity, although it is considered 
generally more serious than TTS because it is a permanent condition. 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.

Acoustically-Induced Bubble Formation Due to Sonars and Other Pressure-
Related Impacts

    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.
    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 referenced to (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 10 m (33 ft) 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 (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 (decompression sickness) 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 (Jepson et al., 2003; Fernandez et al., 2005; 
Fern[aacute]ndez et al., 2012). 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 (ELs) 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, 2012) 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 MF/HF sonar 
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 Nitrogen Decompression 
subsection of the 2019 NWTT DSEIS/OEIS, marine mammals 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.

[[Page 33938]]

    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, Cuvier's 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 
Cuvier's 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 Cuvier's 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 Cuvier's 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 
beaked and Cuvier's 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 Cuvier's 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 MF 
active sonars 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.

Injury Due to Sonar-Induced Acoustic Resonance

    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 
(National Oceanic and Atmospheric Administration, 2002). They modeled 
and evaluated the likelihood that Navy mid-frequency sonar (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 mid-frequency or low-
frequency sonar; 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 mid-frequency sonar 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 Navy's proposed activities.
Physiological Stress
    There is growing interest in monitoring and assessing the impacts 
of stress responses to sound in marine animals. Classic stress 
responses begin when an animal's central nervous system perceives a 
potential threat to its homeostasis. That perception triggers stress 
responses regardless of whether a

[[Page 33939]]

stimulus actually threatens the animal; the mere perception of a threat 
is sufficient to trigger a stress response (Moberg, 2000; Sapolsky et 
al., 2005; Seyle, 1950). Once an animal's central nervous system 
perceives a threat, it mounts a biological response or defense that 
consists of a combination of the four general biological defense 
responses: Behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses.
    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.
    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 hypothalmus-pituitary-adrenal 
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.
    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, which impairs those functions that experience the diversion. 
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'' (Seyle, 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. Note that these examples involved a long-term (days or 
weeks) stress response exposure to stimuli.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments in both laboratory and free-ranging animals (for 
examples see, 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 2019 NWTT DSEIS/OEIS) that our 
understanding of the functions of various stress hormones (for example, 
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.
    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, and social interactions 
with members of the same species 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 (Fair et al., 2014; Meissner et al., 2015; 
Rolland et al., 2012). Anthropogenic stressors potentially include such 
things as fishery interactions, pollution, tourism, and ocean noise.
    Acoustically induced stress in marine mammals is not well 
understood. There are ongoing efforts to improve our understanding of 
how stressors impact marine mammal populations (e.g., King et al., 
2015; New et al., 2013a; New et al., 2013b; Pirotta et al., 2015a), 
however little data exist on the consequences of sound-induced stress 
response (acute or chronic). Factors potentially affecting a marine 
mammal's response to a stressor include the individual's life history 
stage, sex, age, reproductive status, overall physiological and 
behavioral plasticity, 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, 2001a)). Stress responses due to exposure to 
anthropogenic sounds or other stressors and their effects on marine 
mammals have been reviewed (Fair and Becker, 2000; Romano et al., 
2002b) and, more rarely, studied in wild populations (e.g., Romano et 
al., 2002a). For example, Rolland et al. (2012) found that noise 
reduction from reduced ship traffic in the Bay of Fundy was associated 
with decreased stress in North Atlantic right whales. These and other 
studies lead to a reasonable expectation that some marine mammals will 
experience physiological stress responses upon exposure to acoustic 
stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    Other research has also investigated the impact from vessels (both 
whale-watching and general vessel traffic noise), and demonstrated 
impacts do occur (Bain, 2002; Erbe, 2002; Lusseau, 2006; Williams et 
al., 2006; Williams et al., 2009; Noren et al., 2009; Read et al., 
2014; Rolland et al., 2012; Skarke et al., 2014; Williams et al., 2013; 
Williams et al., 2014a; Williams et al., 2014b; Pirotta et al., 2015). 
This body of research has generally investigated impacts associated 
with the presence of chronic stressors, which differ significantly from 
the proposed Navy training and testing

[[Page 33940]]

vessel activities in the NWTT Study Area. For example, in an analysis 
of energy costs to killer whales, Williams et al. (2009) suggested that 
whale-watching in Canada's Johnstone Strait resulted in lost feeding 
opportunities due to vessel disturbance, which could carry higher costs 
than other measures of behavioral change might suggest. Ayres et al. 
(2012) reported on research in the Salish Sea (Washington state) 
involving the measurement of southern resident killer whale fecal 
hormones to assess two potential threats to the species recovery: Lack 
of prey (salmon) and impacts to behavior from vessel traffic. Ayres et 
al. (2012) suggested that the lack of prey overshadowed any population-
level physiological impacts on southern resident killer whales from 
vessel traffic. In a conceptual model developed by the Population 
Consequences of Acoustic Disturbance (PCAD) working group, serum 
hormones were identified as possible indicators of behavioral effects 
that are translated into altered rates of reproduction and mortality 
(NRC, 2005). The Office of Naval Research hosted a workshop (Effects of 
Stress on Marine Mammals Exposed to Sound) in 2009 that focused on this 
topic (ONR, 2009). Ultimately, the PCAD working group issued a report 
(Cochrem, 2014) that summarized information compiled from 239 papers or 
book chapters relating to stress in marine mammals and concluded that 
stress responses can last from minutes to hours and, while we typically 
focus on adverse stress responses, stress response is part of a natural 
process to help animals adjust to changes in their environment and can 
also be either neutral or beneficial.
    Most sound-induced stress response studies in marine mammals have 
focused on acute responses to sound either by measuring catecholamines 
or by measuring heart rate as an assumed proxy for an acute stress 
response. Belugas demonstrated no catecholamine response to the 
playback of oil drilling sounds (Thomas et al., 1990) 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 bottlenose dolphin exposed to the same 
seismic water gun signals did not demonstrate a catecholamine response, 
but did demonstrate a statistically significant elevation in 
aldosterone (Romano et al., 2004), albeit the increase was within the 
normal daily variation observed in this species (St. Aubin et al., 
1996). Increases in heart rate were observed in 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 
(Miksis et al., 2001). Unfortunately, in this study, it cannot be 
determined whether the increase in heart rate was due to stress or an 
anticipation of being reunited with the dolphin to which the 
vocalization belonged. Similarly, a young beluga's heart rate was 
observed to increase 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 may have acclimated to the noise exposure. Kvadsheim et 
al. (2010) 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 bradycardia (decrease in heart rate) was not impacted by the 
sonar exposure. Similarly, Thompson et al. (1998) observed a rapid but 
short-lived decrease in heart rates in harbor and grey seals exposed to 
seismic air guns (cited in Gordon et al., 2003). Williams et al. (2017) 
recently monitored the heart rates of narwhals released from capture 
and found that a profound dive bradycardia persisted, even though 
exercise effort increased dramatically as part of their escape response 
following release. Thus, although some limited evidence suggests that 
tachycardia might occur as part of the acute stress response of animals 
that are at the surface, the dive bradycardia persists during diving 
and might be enhanced in response to an acute stressor.
    Despite the limited amount of data available on sound-induced 
stress responses for marine mammals exposed to anthropogenic sounds, 
studies of other marine animals and terrestrial animals would also lead 
us to expect that some marine mammals experience physiological stress 
responses and, perhaps, physiological responses that would be 
classified as ``distress'' upon exposure to high-frequency, mid-
frequency, and low-frequency sounds. For example, Jansen (1998) 
reported on the relationship between acoustic exposures and 
physiological responses that are indicative of stress responses in 
humans (e.g., elevated respiration and increased heart rates). Jones 
(1998) reported on reductions in human performance when faced with 
acute, repetitive exposures to acoustic disturbance. Trimper et al. 
(1998) reported on the physiological stress responses of osprey to low-
level aircraft noise while Krausman et al. (2004) reported on the 
auditory and physiological stress responses of endangered Sonoran 
pronghorn to military overflights. However, take due to aircraft noise 
is not anticipated as a result of the Navy's activities. Smith et al. 
(2004a, 2004b) identified noise-induced physiological transient stress 
responses in hearing-specialist fish (i.e., goldfish) that accompanied 
short- and long-term hearing losses. Welch and Welch (1970) reported 
physiological and behavioral stress responses that accompanied damage 
to the inner ears of fish and several mammals.
Auditory Masking
    Sound can disrupt behavior through masking, or interfering with, an 
animal's ability to detect, recognize, or discriminate between acoustic 
signals of interest (e.g., those used for intraspecific communication 
and social interactions, prey detection, predator avoidance, or 
navigation) (Richardson et al., 1995; Erbe and Farmer, 2000; Tyack, 
2000; Erbe et al., 2016). 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 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 the 2019 NWTT DSEIS/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

[[Page 33941]]

foraging, and leaving an area, to both signalers and receivers, in an 
attempt to compensate for noise levels (Erbe et al., 2016).
    In humans, significant masking of tonal signals occurs as a result 
of exposure to noise in a narrow band of similar frequencies. As the 
sound level increases, though, the detection of frequencies above those 
of the masking stimulus decreases also. This principle is expected to 
apply to marine mammals as well because of common biomechanical 
cochlear properties across taxa.
    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 (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. 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. (1995b) argued that the maximum radius of 
influence of an industrial 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, Finneran and Branstetter, 2013; Johnson et al., 1989; 
Southall et al., 2000) of the animal or the background noise level 
present. Industrial 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 (e.g., Erbe, 2008), 
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., Branstetter et al., 2013).
    The echolocation calls of toothed whales are subject to masking by 
high-frequency sound. 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). There is also evidence that the directional hearing 
abilities of odontocetes are useful in reducing masking at the high-
frequencies these cetaceans use to echolocate, but not at the low-to-
moderate frequencies they use to communicate (Zaitseva et al., 1980). A 
study by Nachtigall and Supin (2008) 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 (often called 
``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; Cur[eacute] 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 off British Columbia are 
frequently targeted by mammal-eating killer whales. The seals 
acoustically 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 attend to 
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; these 
findings indicate that some recognition of predator cues could be 
missed if the killer whale vocalizations were masked. 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 manmade 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 ship 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). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from commercial vessel

[[Page 33942]]

traffic), contribute to elevated ambient sound levels, thus 
intensifying masking.

Impaired Communication

    In addition to making it more difficult for animals to perceive and 
recognize acoustic cues in their environment, anthropogenic sound 
presents separate challenges for animals that are vocalizing. When they 
vocalize, animals are aware of environmental conditions that affect the 
``active space'' (or communication space) of their vocalizations, which 
is the maximum area within which their vocalizations can be detected 
before it drops to the level of ambient noise (Brenowitz, 2004; Brumm 
et al., 2004; Lohr et al., 2003). Animals are also aware of 
environmental conditions that affect whether listeners can discriminate 
and recognize their vocalizations from other sounds, which is more 
important than simply detecting that a vocalization is occurring 
(Brenowitz, 1982; Brumm et al., 2004; Dooling, 2004, Marten and Marler, 
1977; Patricelli et al., 2006). Most species that vocalize have evolved 
with an ability to make adjustments to their vocalizations to increase 
the signal-to-noise ratio, active space, and recognizability/
distinguishability of their vocalizations in the face of temporary 
changes in background noise (Brumm et al., 2004; Patricelli et al., 
2006). Vocalizing animals can make adjustments to vocalization 
characteristics such as the frequency structure, amplitude, temporal 
structure, and temporal delivery (repetition rate), or may cease to 
vocalize.
    Many animals will combine several of these strategies to compensate 
for high levels of background noise. Anthropogenic sounds that reduce 
the signal-to-noise ratio of animal vocalizations, increase the masked 
auditory thresholds of animals listening for such vocalizations, or 
reduce the active space of an animal's vocalizations impair 
communication between animals. Most animals that vocalize have evolved 
strategies to compensate for the effects of short-term or temporary 
increases in background or ambient noise on their songs or calls. 
Although the fitness consequences of these vocal adjustments are not 
directly known in all instances, like most other trade-offs animals 
must make, some of these strategies probably come at a cost (Patricelli 
et al., 2006). Shifting songs and calls to higher frequencies may also 
impose energetic costs (Lambrechts, 1996). For example, in birds, 
vocalizing more loudly in noisy environments may have energetic costs 
that decrease the net benefits of vocal adjustment and alter a bird's 
energy budget (Brumm, 2004; Wood and Yezerinac, 2006).
    Marine mammals are also known to make vocal changes in response to 
anthropogenic noise. In cetaceans, vocalization changes have been 
reported from exposure to anthropogenic noise sources such as sonar, 
vessel noise, and seismic surveying (see the following for examples: 
Gordon et al., 2003; Di Iorio and Clark, 2010; Hatch et al., 2012; Holt 
et al., 2008; Holt et al., 2011; Lesage et al., 1999; McDonald et al., 
2009; Parks et al., 2007, Risch et al., 2012, Rolland et al., 2012), as 
well as changes in the natural acoustic environment (Dunlop et al., 
2014). Vocal changes can be temporary, or can be persistent. For 
example, model simulation suggests that the increase in starting 
frequency for the North Atlantic right whale upcall over the last 50 
years resulted in increased detection ranges between right whales. The 
frequency shift, coupled with an increase in call intensity by 20 dB, 
led to a call detectability range of less than 3 km to over 9 km 
(Tennessen and Parks, 2016). Holt et al. (2008) measured killer whale 
call source levels and background noise levels in the one to 40 kHz 
band and reported that the whales increased their call source levels by 
one dB SPL for every one dB SPL increase in background noise level. 
Similarly, another study on St. Lawrence River belugas reported a 
similar rate of increase in vocalization activity in response to 
passing vessels (Scheifele et al., 2005). Di Iorio and Clark (2010) 
showed that blue whale calling rates vary in association with seismic 
sparker survey activity, with whales calling more on days with surveys 
than on days without surveys. They suggested that the whales called 
more during seismic survey periods as a way to compensate for the 
elevated noise conditions.
    In some cases, these vocal changes may have fitness consequences, 
such as an increase in metabolic rates and oxygen consumption, as 
observed in bottlenose dolphins when increasing their call amplitude 
(Holt et al., 2015). A switch from vocal communication to physical, 
surface-generated sounds such as pectoral fin slapping or breaching was 
observed for humpback whales in the presence of increasing natural 
background noise levels, indicating that adaptations to masking may 
also move beyond vocal modifications (Dunlop et al., 2010).
    While these changes all represent possible tactics by the sound-
producing animal to reduce the impact of masking, the receiving animal 
can also reduce masking by using active listening strategies such as 
orienting to the sound source, moving to a quieter location, or 
reducing self-noise from hydrodynamic flow by remaining still. The 
temporal structure of noise (e.g., amplitude modulation) may also 
provide a considerable release from masking through comodulation 
masking release (a reduction of masking that occurs when broadband 
noise, with a frequency spectrum wider than an animal's auditory filter 
bandwidth at the frequency of interest, is amplitude modulated) 
(Branstetter and Finneran, 2008; Branstetter et al., 2013). Signal type 
(e.g., whistles, burst-pulse, sonar clicks) and spectral 
characteristics (e.g., frequency modulated with harmonics) may further 
influence masked detection thresholds (Branstetter et al., 2016; 
Cunningham et al., 2014).

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 Navy's low-frequency active sonar (LFAS)/mid-frequency active 
sonar (MFAS)/high-frequency active sonar (HFAS) training and testing 
exercises. Additionally, almost all affected species' vocal repertoires 
span across the frequencies of these sonar sources used by the Navy. 
The closer the characteristics of the masking signal to the signal of 
interest, the more likely masking is to occur. Masking by low-frequency 
or mid-frequency active sonar (LFAS and 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 of most sonars.
    As described in additional detail the 2019 NWTT DSEIS/OEIS, newer 
high-duty cycle or continuous active sonars have more potential to mask 
vocalizations. These sonars transmit more frequently (greater than 80 
percent duty cycle) than traditional sonars, but at a substantially 
lower source level. HFAS, such as pingers that operate at

[[Page 33943]]

higher repetition rates (e.g., 2-10 kHz with harmonics up to 19 kHz, 76 
to 77 pings per minute) (Culik et al., 2001), 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 mid-frequency cetaceans. Continuous 
noise at the same frequency of communicative vocalizations may cause 
disruptions to communication, social interactions, acoustically 
mediated cooperative behaviors, and important environmental cues. There 
is also the potential for the mid-frequency sonar signals to mask 
important environmental cues (e.g., predator or conspectic acoustic 
cues), possibly affecting survivorship for targeted animals. While 
there are currently no available 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).

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, 
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 the 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 modelled 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 (for 
examples see: Holt et al., 2008; Holt et al., 2011; Gervaise et al., 
2012; Williams et al., 2013; Hermannsen et al., 2014; Papale et al., 
2015; Liu et al., 2017).

Behavioral Response/Disturbance

    Behavioral responses to sound are highly variable and context-
specific. 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) 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). Related to the sound itself, the perceived nearness 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), and 
familiarity of the sound may affect the way an animal responds to the 
sound (Southall et al., 2007, DeRuiter et al., 2013). 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. 
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. For example, Goldbogen et al. (2013) demonstrated 
that individual behavioral state was critically important in 
determining response of blue whales to sonar, noting that some 
individuals engaged in deep (>50 m) feeding behavior had greater dive 
responses than those in shallow feeding or non-feeding conditions. Some 
blue whales in the Goldbogen et al. (2013) study that were engaged in 
shallow feeding behavior demonstrated no clear changes in diving or 
movement even when received levels (RLs) were high (~160 dB re: 
1[mu]Pa) for exposures to 3-4 kHz sonar signals, while others showed a 
clear response at exposures at lower received levels of sonar and 
pseudorandom noise.
    Studies by DeRuiter et al. (2012) 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. 
(2013) examined behavioral responses of Cuvier's beaked whales to MF 
sonar and found that whales responded strongly at low received levels 
(RL of 89-127 dB re: 1[mu]Pa) by ceasing normal fluking and 
echolocation, swimming rapidly away, and extending both dive duration 
and subsequent non-foraging intervals when

[[Page 33944]]

the sound source was 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 [mu]Pa) from distant sonar exercises (118 km away) did not 
elicit such responses, suggesting that context may moderate reactions.
    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., is 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 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., 2012 and 2013; 
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. The following subsections provide examples of behavioral 
responses that provide an idea of the variability in behavioral 
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, or 
extrapolated from closely related species when no information exists, 
along with contextual factors.
Flight Response
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, being a component of 
marine mammal strandings associated with sonar activities (Evans and 
England, 2001). If marine mammals respond to Navy vessels that are 
transmitting active sonar in the same way that they might respond to a 
predator, their probability of flight responses should increase when 
they perceive that Navy vessels are approaching them directly, because 
a direct approach may convey detection and intent to capture (Burger 
and Gochfeld, 1981, 1990; Cooper, 1997, 1998). There are limited data 
on flight response for marine mammals in water; however, there are 
examples of this response in species on land. For instance, the 
probability of flight responses in Dall's sheep Ovis dalli dalli (Frid, 
2001), hauled-out ringed seals Phoca hispida (Born et al., 1999), 
Pacific brant (Branta bernicl nigricans), and Canada geese (B. 
canadensis) increased as a helicopter or fixed-wing aircraft more 
directly approached groups of these animals (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).
Response to Predator
    As discussed earlier, evidence suggests that at least some marine 
mammals have the ability to acoustically identify potential predators. 
For example, harbor seals that reside in the coastal waters off British 
Columbia are frequently targeted by certain groups of killer whales, 
but not others. The seals discriminate between the calls of threatening 
and non-threatening killer whales (Deecke et al., 2002), a capability 
that should increase survivorship while reducing the energy required 
for attending to and responding to all killer whale calls. The 
occurrence of masking or hearing impairment provides a means by which 
marine mammals may be prevented from responding to the acoustic cues 
produced by their predators. Whether or not this is a

[[Page 33945]]

possibility depends on the duration of the masking/hearing impairment 
and the likelihood of encountering a predator during the time that 
predator cues are impeded.
Alteration of Diving or Movement
    Changes in dive behavior can vary widely. They may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Ng and Leung, 2003; Nowacek et al.; 2004; Goldbogen et 
al., 2013a, 2013b). Variations in dive behavior may reflect 
interruptions in biologically significant activities (e.g., foraging) 
or they may be of little biological significance. Variations in dive 
behavior may also expose an animal to potentially harmful conditions 
(e.g., increasing the chance of ship-strike) or may serve as an 
avoidance response that enhances survivorship. The impact of a 
variation in diving resulting from an acoustic exposure depends on what 
the animal is doing at the time of the exposure and the type and 
magnitude of the response.
    Nowacek et al. (2004) reported disruptions of dive behaviors in 
foraging North Atlantic right whales when exposed to an alerting 
stimulus, an action, they noted, that could lead to an increased 
likelihood of ship strike. However, the whales did not respond to 
playbacks of either right whale social sounds or vessel noise, 
highlighting the importance of the sound characteristics in producing a 
behavioral reaction. Conversely, Indo-Pacific humpback dolphins have 
been observed to dive for longer periods of time in areas where vessels 
were present and/or approaching (Ng and Leung, 2003). In both of these 
studies, the influence of the sound exposure cannot be decoupled from 
the physical presence of a surface vessel, thus complicating 
interpretations of the relative contribution of each stimulus to the 
response. Indeed, the presence of surface vessels, their approach, and 
speed of approach, seemed to be significant factors in the response of 
the Indo-Pacific humpback dolphins (Ng and Leung, 2003). Low-frequency 
signals of the Acoustic Thermometry of Ocean Climate (ATOC) sound 
source were not found to affect dive times of humpback whales in 
Hawaiian waters (Frankel and Clark, 2000) or to overtly affect elephant 
seal dives (Costa et al., 2003). They did, however, produce subtle 
effects that varied in direction and degree among the individual seals, 
illustrating the equivocal nature of behavioral effects and consequent 
difficulty in defining and predicting them. Lastly, as noted 
previously, DeRuiter et al. (2013) noted that distance from a sound 
source may moderate marine mammal reactions in their study of Cuvier's 
beaked whales, which showed the whales swimming rapidly and silently 
away when a sonar signal was 3.4-9.5 km away while showing no such 
reaction to the same signal when the signal was 118 km away even though 
the received levels were similar.
Foraging
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Harris et al., 2017; Madsen et al., 2006a; Nowacek et al.; 2004; 
Yazvenko et al., 2007). A determination of whether foraging disruptions 
incur fitness consequences would require information on or estimates of 
the energetic requirements of the affected individuals and the 
relationship between prey availability, foraging effort and success, 
and the life history stage of the animal.
    Noise from seismic surveys was not found to impact the feeding 
behavior in western grey whales off the coast of Russia (Yazvenko et 
al., 2007). Visual tracking, passive acoustic monitoring, and movement 
recording tags were used to quantify sperm whale behavior prior to, 
during, and following exposure to air gun arrays at received levels in 
the range 140-160 dB at distances of 7-13 km, following a phase-in of 
sound intensity and full array exposures at 1-13 km (Madsen et al., 
2006a; Miller et al., 2009). Sperm whales did not exhibit horizontal 
avoidance behavior at the surface. However, foraging behavior may have 
been affected. The sperm whales exhibited 19 percent less vocal (buzz) 
rate during full exposure relative to post exposure, and the whale that 
was approached most closely had an extended resting period and did not 
resume foraging until the air guns had ceased firing. The remaining 
whales continued to execute foraging dives throughout exposure; 
however, swimming movements during foraging dives were six percent 
lower during exposure than control periods (Miller et al., 2009). These 
data raise concerns that air gun surveys may impact foraging behavior 
in sperm whales, although more data are required to understand whether 
the differences were due to exposure or natural variation in sperm 
whale behavior (Miller et al., 2009).
    Balaenopterid whales exposed to moderate low-frequency signals 
similar to the ATOC sound source demonstrated no variation in foraging 
activity (Croll et al., 2001), whereas five out of six North Atlantic 
right whales exposed to an acoustic alarm interrupted their foraging 
dives (Nowacek et al., 2004). Although the received SPLs were similar 
in the latter two studies, the frequency, duration, and temporal 
pattern of signal presentation were different. These factors, as well 
as differences in species sensitivity, are likely contributing factors 
to the differential response. Blue whales exposed to mid-frequency 
sonar in the Southern California Bight were less likely to produce low 
frequency calls usually associated with feeding behavior (Melc[oacute]n 
et al., 2012). However, Melc[oacute]n et al. (2012) were unable to 
determine if suppression of low frequency calls reflected a change in 
their feeding performance or abandonment of foraging behavior and 
indicated that implications of the documented responses are unknown. 
Further, it is not known whether the lower rates of calling actually 
indicated a reduction in feeding behavior or social contact since the 
study used data from remotely deployed, passive acoustic monitoring 
buoys. In contrast, blue whales increased their likelihood of calling 
when ship noise was present, and decreased their likelihood of calling 
in the presence of explosive noise, although this result was not 
statistically significant (Melc[oacute]n et al., 2012). Additionally, 
the likelihood of an animal calling decreased with the increased 
received level of mid-frequency sonar, beginning at a SPL of 
approximately 110-120 dB re: 1 [mu]Pa (Melc[oacute]n et al., 2012). 
Results from behavioral response studies in Southern California waters 
indicated that, in some cases and at low received levels, tagged blue 
whales responded to mid-frequency sonar but that those responses were 
were generally brief, of low to moderate severity, and highly dependent 
on exposure context (Southall et al., 2011; Southall et al., 2012b, 
Southall et al., 2019b). Information on or estimates of the energetic 
requirements of the individuals and the relationship between prey 
availability, foraging effort and success, and the life history stage 
of the animal will help better inform a

[[Page 33946]]

determination of whether foraging disruptions incur fitness 
consequences. Surface feeding blue whales did not show a change in 
behavior in response to mid-frequency simulated and real sonar sources 
with received levels between 90 and 179 dB re: 1 [mu]Pa, but deep 
feeding and non-feeding whales showed temporary reactions including 
cessation of feeding, reduced initiation of deep foraging dives, 
generalized avoidance responses, and changes to dive behavior. The 
behavioral responses they observed were generally brief, of low to 
moderate severity, and highly dependent on exposure context (behavioral 
state, source-to-whale horizontal range, and prey availability) 
(DeRuiter et al., 2017; Goldbogen et al., 2013b; Sivle et al., 2015). 
Goldbogen et al. (2013b) indicate that disruption of feeding and 
displacement could impact individual fitness and health. However, for 
this to be true, we would have to assume that an individual whale could 
not compensate for this lost feeding opportunity by either immediately 
feeding at another location, by feeding shortly after cessation of 
acoustic exposure, or by feeding at a later time. There is no 
indication this is the case, particularly since unconsumed prey would 
likely still be available in the environment in most cases following 
the cessation of acoustic exposure.
    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. In fact, when the prey field was mapped and used 
as a covariate in similar models looking for a response in the same 
blue whales, the response in deep-feeding behavior by blue whales was 
even more apparent, reinforcing the need for contextual variables to be 
included when assessing behavioral responses (Friedlaender et al., 
2016).
Breathing
    Respiration naturally varies with different behaviors and 
variations in respiration rate as a function of acoustic exposure can 
be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Mean exhalation rates of gray whales at rest and while 
diving were found to be unaffected by seismic surveys conducted 
adjacent to the whale feeding grounds (Gailey et al., 2007). Studies 
with captive harbor porpoises showed increased respiration rates upon 
introduction of acoustic alarms (Kastelein et al., 2001; Kastelein et 
al., 2006a) and emissions for underwater data transmission (Kastelein 
et al., 2005). However, exposure of the same acoustic alarm to a 
striped dolphin under the same conditions did not elicit a response 
(Kastelein et al., 2006a), again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure.
Social Relationships
    Social interactions between mammals can be affected by noise via 
the disruption of communication signals or by the displacement of 
individuals. Disruption of social relationships therefore depends on 
the disruption of other behaviors (e.g., avoidance, masking, etc.). 
Sperm whales responded to military sonar, apparently from a submarine, 
by dispersing from social aggregations, moving away from the sound 
source, remaining relatively silent, and becoming difficult to approach 
(Watkins et al., 1985). In contrast, sperm whales in the Mediterranean 
that were exposed to submarine sonar continued calling (J. Gordon pers. 
comm. cited in Richardson et al., 1995). Long-finned pilot whales 
exposed to three types of disturbance--playbacks of killer whale 
sounds, naval sonar exposure, and tagging--resulted in increased group 
sizes (Visser et al., 2016). In response to sonar, pilot whales also 
spent more time at the surface with other members of the group (Visser 
et al., 2016). However, social disruptions must be considered in 
context of the relationships that are affected. While some disruptions 
may not have deleterious effects, others, such as long-term or repeated 
disruptions of mother/calf pairs or interruption of mating behaviors, 
have the potential to affect the growth and survival or reproductive 
effort/success of individuals.
Vocalizations (Also See Auditory Masking Section)
    Vocal changes in response to anthropogenic noise can occur across 
the repertoire of sound production modes used by marine mammals, such 
as whistling, echolocation click production, calling, and singing. 
Changes in vocalization behavior that may result in response to 
anthropogenic noise can occur for any of these modes and may result 
from a need to compete with an increase in background noise or may 
reflect an increased vigilance or a startle response. For example, in 
the presence of potentially masking signals (low-frequency active 
sonar), humpback whales have been observed to increase the length of 
their songs (Miller et al., 2000; Fristrup et al., 2003). A similar 
compensatory effect for the presence of low-frequency vessel noise has 
been suggested for right whales; right whales have been 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; Roland et al., 2012). Killer whales off the northwestern 
coast of the United States have been observed to increase the duration 
of primary calls once a threshold in observing vessel density (e.g., 
whale watching) was reached, which has been suggested as a response to 
increased masking noise produced by the vessels (Foote et al., 2004; 
NOAA, 2014b). In contrast, both sperm and pilot whales potentially 
ceased sound production during the Heard Island feasibility test 
(Bowles et al., 1994), although it cannot be absolutely determined 
whether the inability to acoustically detect the animals was due to the 
cessation of sound production or the displacement of animals from the 
area.
    Cerchio et al. (2014) used passive acoustic monitoring to document 
the presence of singing humpback whales off the coast of northern 
Angola and to opportunistically test for the effect of seismic survey 
activity on the number of singing whales. Two recording units were 
deployed between March and December 2008 in the offshore environment; 
numbers of singers were counted every hour. Generalized Additive Mixed 
Models were used to assess the effect of survey day (seasonality), hour 
(diel variation), moon phase, and received levels of noise (measured 
from a single pulse during each ten-minute sampled period) on singer 
number. The number of singers significantly decreased with increasing 
received level of noise, suggesting that humpback whale communication 
was disrupted to some extent by the survey activity.
    Castellote et al. (2012) reported acoustic and behavioral changes 
by fin whales in response to shipping and air gun noise. Acoustic 
features of fin

[[Page 33947]]

whale song notes recorded in the Mediterranean Sea and northeast 
Atlantic Ocean were compared for areas with different shipping noise 
levels and traffic intensities and during an air gun survey. During the 
first 72 hours of the survey, a steady decrease in song received levels 
and bearings to singers indicated that whales moved away from the 
acoustic source and out of a Navy study area. This displacement 
persisted for a time period well beyond the 10-day duration of air gun 
activity, providing evidence that fin whales may avoid an area for an 
extended period in the presence of increased noise. The authors 
hypothesize that fin whale acoustic communication is modified to 
compensate for increased background noise and that a sensitization 
process may play a role in the observed temporary displacement.
    Seismic pulses at average received levels of 131 dB re: 1 
micropascal squared per second ([mu]Pa2-s) caused blue whales to 
increase call production (Di Iorio and Clark, 2010). In contrast, 
McDonald et al. (1995) tracked a blue whale with seafloor seismometers 
and reported that it stopped vocalizing and changed its travel 
direction at a range of 10 km from the seismic vessel (estimated 
received level 143 dB re: 1 [mu]Pa peak-to-peak). Blackwell et al. 
(2013) found that bowhead whale call rates dropped significantly at 
onset of air gun use at sites with a median distance of 41-45 km from 
the survey. Blackwell et al. (2015) expanded this analysis to show that 
whales actually increased calling rates as soon as air gun signals were 
detectable before ultimately decreasing calling rates at higher 
received levels (i.e., 10-minute cumulative sound exposure level (cSEL) 
of ~127 dB). Overall, these results suggest that bowhead whales may 
adjust their vocal output in an effort to compensate for noise before 
ceasing vocalization effort and ultimately deflecting from the acoustic 
source (Blackwell et al., 2013, 2015). Captive bottlenose dolphins 
sometimes vocalized after an exposure to impulse sound from a seismic 
water gun (Finneran et al., 2010a). These studies demonstrate that even 
low levels of noise received far from the noise source can induce 
changes in vocalization and/or behavioral responses.
Avoidance
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors. Richardson et al. (1995) noted that avoidance reactions are 
the most obvious manifestations of disturbance in marine mammals. 
Avoidance is qualitatively different from the flight response, but also 
differs in the magnitude of the response (i.e., directed movement, rate 
of travel, etc.). Oftentimes avoidance is temporary, and animals return 
to the area once the noise has ceased. Acute avoidance responses have 
been observed in captive porpoises and pinnipeds exposed to a number of 
different sound sources (Kastelein et al., 2001; Finneran et al., 2003; 
Kastelein et al., 2006a; Kastelein et al., 2006b). Short-term avoidance 
of seismic surveys, low frequency emissions, and acoustic deterrents 
have also been noted in wild populations of odontocetes (Bowles et al., 
1994; Goold, 1996; 1998; Stone et al., 2000; Morton and Symonds, 2002) 
and to some extent in mysticetes (Gailey et al., 2007). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann et 
al., 2006). Longer term or repetitive/chronic displacement for some 
dolphin groups and for manatees has been suggested to be due to the 
presence of chronic vessel noise (Haviland-Howell et al., 2007; Miksis-
Olds et al., 2007). Gray whales have been reported deflecting from 
customary migratory paths in order to avoid noise from air gun surveys 
(Malme et al., 1984). Humpback whales showed avoidance behavior in the 
presence of an active air gun array during observational studies and 
controlled exposure experiments in western Australia (McCauley et al., 
2000a).
    As discussed earlier, Forney et al. (2017) detailed the potential 
effects of noise on marine mammal populations with high site fidelity, 
including displacement and auditory masking, noting that a lack of 
observed response does not imply absence of fitness costs and that 
apparent tolerance of disturbance may have population-level impacts 
that are less obvious and difficult to document. Avoidance of overlap 
between disturbing noise and areas and/or times of particular 
importance for sensitive species may be critical to avoiding 
population-level impacts because (particularly for animals with high 
site fidelity) there may be a strong motivation to remain in the area 
despite negative impacts. Forney et al. (2017) stated that, for these 
animals, remaining in a disturbed area may reflect a lack of 
alternatives rather than a lack of effects. The authors discuss several 
case studies, including western Pacific gray whales, which are a small 
population of mysticetes believed to be adversely affected by oil and 
gas development off Sakhalin Island, Russia (Weller et al., 2002; 
Reeves et al., 2005). Western gray whales display a high degree of 
interannual site fidelity to the area for foraging purposes, and 
observations in the area during air gun surveys have shown the 
potential for harm caused by displacement from such an important area 
(Weller et al., 2006; Johnson et al., 2007). Forney et al. (2017) also 
discuss beaked whales, noting that anthropogenic effects in areas where 
they are resident could cause severe biological consequences, in part 
because displacement may adversely affect foraging rates, reproduction, 
or health, while an overriding instinct to remain could lead to more 
severe acute effects.
    In 1998, the Navy conducted a Low Frequency Sonar Scientific 
Research Program (LFS SRP) specifically to study behavioral responses 
of several species of marine mammals to exposure to LF sound, including 
one phase that focused on the behavior of gray whales to low frequency 
sound signals. The objective of this phase of the LFS SRP was to 
determine whether migrating gray whales respond more strongly to 
received levels, sound gradient, or distance from the source, and to 
compare whale avoidance responses to an LF source in the center of the 
migration corridor versus in the offshore portion of the migration 
corridor. A single source was used to broadcast LFAS sounds at received 
levels of 170-178 dB re: 1 [mu]Pa. The Navy reported that the whales 
showed some avoidance responses when the source was moored one mile 
(1.8 km) offshore, and located within the migration path, but the 
whales returned to their migration path when they were a few kilometers 
beyond the source. When the source was moored two miles (3.7 km) 
offshore, responses were much less, even when the source level was 
increased to achieve the same received levels in the middle of the 
migration corridor as whales received when the source was located 
within the migration corridor (Clark et al., 1999). In addition, the 
researchers noted that the offshore whales did not seem to avoid the 
louder offshore source.
    Also during the LFS SRP, researchers sighted numerous odontocete 
and pinniped species in the vicinity of the sound exposure tests with 
LFA sonar. The MF and HF hearing specialists present in California and 
Hawaii showed no immediately obvious responses or changes in sighting 
rates as a function of source conditions. Consequently, the researchers

[[Page 33948]]

concluded that none of these species had any obvious behavioral 
reaction to LFA sonar signals at received levels similar to those that 
produced only minor short-term behavioral responses in the baleen 
whales (i.e., LF hearing specialists). Thus, for odontocetes, the 
chances of injury and/or significant behavioral responses to LFA sonar 
would be low given the MF/HF specialists' observed lack of response to 
LFA sounds during the LFS SRP and due to the MF/HF frequencies to which 
these animals are adapted to hear (Clark and Southall, 2009).
    Maybaum (1993) conducted sound playback experiments to assess the 
effects of MFAS on humpback whales in Hawaiian waters. Specifically, 
she exposed focal pods to sounds of a 3.3-kHz sonar pulse, a sonar 
frequency sweep from 3.1 to 3.6 kHz, and a control (blank) tape while 
monitoring behavior, movement, and underwater vocalizations. The two 
types of sonar signals differed in their effects on the humpback 
whales, but both resulted in avoidance behavior. The whales responded 
to the pulse by increasing their distance from the sound source and 
responded to the frequency sweep by increasing their swimming speeds 
and track linearity. In the Caribbean, sperm whales avoided exposure to 
mid-frequency submarine sonar pulses, in the range of 1,000 Hz to 
10,000 Hz (IWC, 2005).
    Kvadsheim et al. (2007) conducted a controlled exposure experiment 
in which killer whales fitted with D-tags were exposed to mid-frequency 
active sonar (Source A: A 1.0 second upsweep 209 dB at 1-2 kHz every 10 
seconds for 10 minutes; Source B: with a 1.0 second upsweep 197 dB at 
6-7 kHz every 10 seconds for 10 minutes). When exposed to Source A, a 
tagged whale and the group it was traveling with did not appear to 
avoid the source. When exposed to Source B, the tagged whales along 
with other whales that had been carousel feeding, where killer whales 
cooperatively herd fish schools into a tight ball towards the surface 
and feed on the fish which have been stunned by tailslaps, and 
subsurface feeding (Simila, 1997) ceased feeding during the approach of 
the sonar and moved rapidly away from the source. When exposed to 
Source B, Kvadsheim et al. (2007) reported that a tagged killer whale 
seemed to try to avoid further exposure to the sound field by the 
following behaviors: Immediately swimming away (horizontally) from the 
source of the sound; engaging in a series of erratic and frequently 
deep dives that seemed to take it below the sound field; or swimming 
away while engaged in a series of erratic and frequently deep dives. 
Although the sample sizes in this study are too small to support 
statistical analysis, the behavioral responses of the killer whales 
were consistent with the results of other studies.
    Southall et al. (2007) reviewed the available literature on marine 
mammal hearing and physiological and behavioral responses to human-made 
sound with the goal of proposing exposure criteria for certain effects. 
This peer-reviewed compilation of literature is very valuable, though 
Southall et al. (2007) note that not all data are equal and some have 
poor statistical power, insufficient controls, and/or limited 
information on received levels, background noise, and other potentially 
important contextual variables. Such data were reviewed and sometimes 
used for qualitative illustration, but no quantitative criteria were 
recommended for behavioral responses. All of the studies considered, 
however, contain an estimate of the received sound level when the 
animal exhibited the indicated response.
    In the Southall et al. (2007) publication, for the purposes of 
analyzing responses of marine mammals to anthropogenic sound and 
developing criteria, the authors differentiate between single pulse 
sounds, multiple pulse sounds, and non-pulse sounds. LFAS/MFAS/HFAS are 
considered non-pulse sounds. Southall et al. (2007) summarize the 
studies associated with low-frequency, mid-frequency, and high-
frequency cetacean and pinniped responses to non-pulse sounds, based 
strictly on received level, in Appendix C of their article (referenced 
and summarized in the following paragraphs).
    The studies that address responses of low-frequency cetaceans to 
non-pulse sounds include data gathered in the field and related to 
several types of sound sources (of varying similarity to active sonar) 
including: Vessel noise, drilling and machinery playback, low-frequency 
M-sequences (sine wave with multiple phase reversals) playback, 
tactical low-frequency active sonar playback, drill ships, ATOC source, 
and non-pulse playbacks. These studies generally indicate no (or very 
limited) responses to received levels in the 90 to 120 dB re: 1 [mu]Pa 
range and an increasing likelihood of avoidance and other behavioral 
effects in the 120 to 160 dB re: 1 [mu]Pa range. As mentioned earlier, 
though, contextual variables play a very important role in the reported 
responses and the severity of effects are not linear when compared to 
received level. Also, few of the laboratory or field datasets had 
common conditions, behavioral contexts, or sound sources, so it is not 
surprising that responses differ.
    The studies that address responses of mid-frequency cetaceans to 
non-pulse sounds include data gathered both in the field and the 
laboratory and related to several different sound sources (of varying 
similarity to active sonar) including: Pingers, drilling playbacks, 
ship and ice-breaking noise, vessel noise, Acoustic Harassment Devices 
(AHDs), Acoustic Deterrent Devices (ADDs), MFAS, and non-pulse bands 
and tones. Southall et al. (2007) were unable to come to a clear 
conclusion regarding the results of these studies. In some cases, 
animals in the field showed significant responses to received levels 
between 90 and 120 dB re: 1 [mu]Pa, while in other cases these 
responses were not seen in the 120 to 150 dB re: 1 [mu]Pa range. The 
disparity in results was likely due to contextual variation and the 
differences between the results in the field and laboratory data 
(animals typically responded at lower levels in the field).
    The studies that address responses of high-frequency cetaceans to 
non-pulse sounds include data gathered both in the field and the 
laboratory and related to several different sound sources (of varying 
similarity to active sonar) including: Pingers, AHDs, and various 
laboratory non-pulse sounds. All of these data were collected from 
harbor porpoises. Southall et al. (2007) concluded that the existing 
data indicate that harbor porpoises are likely sensitive to a wide 
range of anthropogenic sounds at low received levels (~90 to 120 dB re: 
1 [mu]Pa), at least for initial exposures. All recorded exposures above 
140 dB re: 1 [mu]Pa induced profound and sustained avoidance behavior 
in wild harbor porpoises (Southall et al., 2007). Rapid habituation was 
noted in some but not all studies. There are no data to indicate 
whether other high frequency cetaceans are as sensitive to 
anthropogenic sound as harbor porpoises.
    The studies that address the responses of pinnipeds in water to 
non-impulsive sounds include data gathered both in the field and the 
laboratory and related to several different sound sources including: 
AHDs, ATOC, various non-pulse sounds used in underwater data 
communication, underwater drilling, and construction noise. Few studies 
existed with enough information to include them in the analysis. The 
limited data suggested that exposures to non-pulse sounds between 90 
and 140 dB re: 1 [mu]Pa generally do not result in strong behavioral 
responses in pinnipeds in water, but no data exist at higher received 
levels.

[[Page 33949]]

    In 2007, the first in a series of behavioral response studies (BRS) 
on deep diving odontocetes conducted by NMFS, Navy, and other 
scientists showed one Blainville's beaked whale responding to an MFAS 
playback. Tyack et al. (2011) indicates that the playback began when 
the tagged beaked whale was vocalizing at depth (at the deepest part of 
a typical feeding dive), following a previous control with no sound 
exposure. The whale appeared to stop clicking significantly earlier 
than usual, when exposed to MF signals in the 130-140 dB (rms) received 
level range. After a few more minutes of the playback, when the 
received level reached a maximum of 140-150 dB, the whale ascended on 
the slow side of normal ascent rates with a longer than normal ascent, 
at which point the exposure was terminated. The results are from a 
single experiment and a greater sample size is needed before robust and 
definitive conclusions can be drawn. Tyack et al. (2011) also indicates 
that Blainville's beaked whales appear to be sensitive to noise at 
levels well below expected TTS (~160 dB re: 1[mu] Pa). This sensitivity 
was manifested by an adaptive movement away from a sound source. This 
response was observed irrespective of whether the signal transmitted 
was within the band width of MFAS, which suggests that beaked whales 
may not respond to the specific sound signatures. Instead, they may be 
sensitive to any pulsed sound from a point source in this frequency 
range of the MFAS transmission. The response to such stimuli appears to 
involve the beaked whale increasing the distance between it and the 
sound source. Overall the results from the 2007-2008 study showed a 
change in diving behavior of the Blainville's beaked whale to playback 
of MFAS and predator sounds (Boyd et al., 2008; Southall et al., 2009; 
Tyack et al., 2011).
    Stimpert et al. (2014) tagged a Baird's beaked whale, which was 
subsequently exposed to simulated MFAS. Received levels of sonar on the 
tag increased to a maximum of 138 dB re: 1 [mu]Pa, which occurred 
during the first exposure dive. Some sonar received levels could not be 
measured due to flow noise and surface noise on the tag.
    Reaction to mid-frequency sounds included premature cessation of 
clicking and termination of a foraging dive, and a slower ascent rate 
to the surface. Results from a similar behavioral response study in 
southern California waters were presented for the 2010-2011 field 
season (Southall et al., 2011; DeRuiter et al., 2013b). DeRuiter et al. 
(2013b) presented results from two Cuvier's beaked whales that were 
tagged and exposed to simulated MFAS during the 2010 and 2011 field 
seasons of the southern California behavioral response study. The 2011 
whale was also incidentally exposed to MFAS from a distant naval 
exercise. Received levels from the MFAS signals from the controlled and 
incidental exposures were calculated as 84-144 and 78-106 dB re: 1 
[mu]Pa rms, respectively. Both whales showed responses to the 
controlled exposures, ranging from initial orientation changes to 
avoidance responses characterized by energetic fluking and swimming 
away from the source. However, the authors did not detect similar 
responses to incidental exposure to distant naval sonar exercises at 
comparable received levels, indicating that context of the exposures 
(e.g., source proximity, controlled source ramp-up) may have been a 
significant factor. Specifically, this result suggests that caution is 
needed when using marine mammal response data collected from smaller, 
nearer sound sources to predict at what received levels animals may 
respond to larger sound sources that are significantly farther away--as 
the distance of the source appears to be an important contextual 
variable and animals may be less responsive to sources at notably 
greater distances. Cuvier's beaked whale responses suggested particular 
sensitivity to sound exposure as consistent with results for 
Blainville's beaked whale. Similarly, beaked whales exposed to sonar 
during British training exercises stopped foraging (DSTL, 2007), and 
preliminary results of controlled playback of sonar may indicate 
feeding/foraging disruption of killer whales and sperm whales (Miller 
et al., 2011).
    In the 2007-2008 Bahamas study, playback sounds of a potential 
predator--a killer whale--resulted in a similar but more pronounced 
reaction, which included longer inter-dive intervals and a sustained 
straight-line departure of more than 20 km from the area (Boyd et al., 
2008; Southall et al., 2009; Tyack et al., 2011). The authors noted, 
however, that the magnified reaction to the predator sounds could 
represent a cumulative effect of exposure to the two sound types since 
killer whale playback began approximately two hours after MF source 
playback. Pilot whales and killer whales off Norway also exhibited 
horizontal avoidance of a transducer with outputs in the mid-frequency 
range (signals in the 1-2 kHz and 6-7 kHz ranges) (Miller et al., 
2011). Additionally, separation of a calf from its group during 
exposure to MFAS playback was observed on one occasion (Miller et al., 
2011, 2012). Miller et al. (2012) noted that this single observed 
mother-calf separation was unusual for several reasons, including the 
fact that the experiment was conducted in an unusually narrow fjord 
roughly one km wide and that the sonar exposure was started unusually 
close to the pod including the calf. Both of these factors could have 
contributed to calf separation. In contrast, preliminary analyses 
suggest that none of the pilot whales or false killer whales in the 
Bahamas showed an avoidance response to controlled exposure playbacks 
(Southall et al., 2009).
    In the 2010 BRS study, researchers again used controlled exposure 
experiments to carefully measure behavioral responses of individual 
animals to sound exposures of MFAS and pseudo-random noise. For each 
sound type, some exposures were conducted when animals were in a 
surface feeding (approximately 164 ft (50 m) or less) and/or 
socializing behavioral state and others while animals were in a deep 
feeding (greater than 164 ft (50 m)) and/or traveling mode. The 
researchers conducted the largest number of controlled exposure 
experiments on blue whales (n=19) and of these, 11 controlled exposure 
experiments involved exposure to the MFAS sound type. For the majority 
of controlled exposure experiment transmissions of either sound type, 
they noted few obvious behavioral responses detected either by the 
visual observers or on initial inspection of the tag data. The 
researchers observed that throughout the controlled exposure experiment 
transmissions, up to the highest received sound level (absolute RMS 
value approximately 160 dB re: 1 [mu]Pa with signal-to-noise ratio 
values over 60 dB), two blue whales continued surface feeding behavior 
and remained at a range of around 3,820 ft (1,000 m) from the sound 
source (Southall et al., 2011). In contrast, another blue whale (later 
in the day and greater than 11.5 mi (18.5 km; 10 nmi) from the first 
controlled exposure experiment location) exposed to the same stimulus 
(MFA) while engaged in a deep feeding/travel state exhibited a 
different response. In that case, the blue whale responded almost 
immediately following the start of sound transmissions when received 
sounds were just above ambient background levels (Southall et al., 
2011). The authors note that this kind of temporary avoidance behavior 
was not evident in any of the nine controlled exposure experiments 
involving blue whales

[[Page 33950]]

engaged in surface feeding or social behaviors, but was observed in 
three of the ten controlled exposure experiments for blue whales in 
deep feeding/travel behavioral modes (one involving MFA sonar; two 
involving pseudo-random noise) (Southall et al., 2011). The results of 
this study, as well as the results of the DeRuiter et al. (2013) study 
of Cuvier's beaked whales discussed above, further illustrate the 
importance of behavioral context in understanding and predicting 
behavioral responses.
    Through analysis of the behavioral response studies, a preliminary 
overarching effect of greater sensitivity to all anthropogenic 
exposures was seen in beaked whales compared to the other odontocetes 
studied (Southall et al., 2009). Therefore, recent studies have focused 
specifically on beaked whale responses to active sonar transmissions or 
controlled exposure playback of simulated sonar on various military 
ranges (Defence Science and Technology Laboratory, 2007; Claridge and 
Durban, 2009; Moretti et al., 2009; McCarthy et al., 2011; Miller et 
al., 2012; Southall et al., 2011, 2012a, 2012b, 2013, 2014; Tyack et 
al., 2011). In the Bahamas, Blainville's beaked whales located on the 
instrumented range will move off-range during sonar use and return only 
after the sonar transmissions have stopped, sometimes taking several 
days to do so (Claridge and Durban 2009; Moretti et al., 2009; McCarthy 
et al., 2011; Tyack et al., 2011). Moretti et al. (2014) used 
recordings from seafloor-mounted hydrophones at the Atlantic Undersea 
Test and Evaluation Center (AUTEC) to analyze the probability of 
Blainsville's beaked whale dives before, during, and after Navy sonar 
exercises.
    Southall et al. (2016) indicates that results from Tyack et al. 
(2011), Miller et al. (2015), Stimpert et al. (2014), and DeRuiter et 
al. (2013) beaked whale studies demonstrate clear, strong, and 
pronounced but varied behavioral changes including avoidance with 
associated energetic swimming and cessation of individual foraging 
dives at quite low received levels (~100 to 135 dB re: 1 Pa) for 
exposures to simulated or active MF military sonars (1-8 kHz) with 
sound sources approximately 2-5 km away. Similar responses by beaked 
whales to sonar have been documented by Stimpert et al., 2014, Falcone 
et al., 2017, DiMarzio et al., 2018, and Joyce et al., 2019. However, 
there are a number of variables influencing response or non-response 
including source distance (close vs. far), received sound levels, and 
other contextual variables such as other sound sources (e.g., vessels, 
etc.) (Manzano-Roth et al., 2016, Falcone et al., 2017, Harris et al., 
2018). Wensveen et al. (2019) found northern bottlenose whales to avoid 
sonar out to distances of 28 km, but these distances are well in line 
with those observed on Navy ranges (Manzano-Roth et al., 2016; Joyce et 
al., 2019) where the animals return once the sonar has ceased. 
Furthermore, beaked whales have also shown response to other non-sonar 
anthropogenic sounds such as commercial shipping and echosounders (Soto 
et al., 2006, Pirotta et al., 2012, Cholewiak et al., 2017). Pirotta et 
al. (2012) documented broadband ship noise causing a significant change 
in beaked whale behavior up to at least 5.2 km away from the vessel. 
Even though beaked whales appear to be sensitive to anthropogenic 
sounds, the level of response at the population level does not appear 
to be significant based on over a decade of research at two heavily 
used Navy training areas in the Pacific (Falcone et al., 2012, Schorr 
et al., 2014, DiMarzio et al., 2018, Schorr et al., 2019). With the 
exception of seasonal patterns, DiMarzio et al. (2018) did not detect 
any changes in annual Cuvier's beaked whale abundance estimates in 
Southern California derived from passive acoustic echolocation 
detections over nine years (2010-2018). Similar results for 
Blainville's beaked whales abundance estimates over several years was 
documented in Hawaii (Henderson et al., 2016;, DiMarzio et al., 2018). 
Visually, there have been documented repeated sightings in southern 
California of the same individual Cuvier's beaked whales over 10 years, 
sightings of mother-calf pairs, and recently sightings of the same 
mothers with their second calf (Falcone et al., 2012; Schorr et al., 
2014; Schorr et al., 2019; Schorr, unpublished data).
    Baleen whales have shown a variety of responses to impulse sound 
sources, including avoidance, reduced surface intervals, altered 
swimming behavior, and changes in vocalization rates (Richardson et 
al., 1995; Gordon et al., 2003; Southall, 2007). While most bowhead 
whales did not show active avoidance until within 8 km of seismic 
vessels (Richardson et al., 1995), some whales avoided vessels by more 
than 20 km at received levels as low as 120 dB re: 1 [mu]Pa rms. 
Additionally, Malme et al. (1988) observed clear changes in diving and 
respiration patterns in bowheads at ranges up to 73 km from seismic 
vessels, with received levels as low as 125 dB re: 1 [mu]Pa.
    Gray whales migrating along the United States West Coast showed 
avoidance responses to seismic vessels by 10 percent of animals at 164 
dB re: 1 [micro]Pa, and by 90 percent of animals at 190 dB re: 1 
[micro]Pa, with similar results for whales in the Bering Sea (Malme, 
1986; 1988). In contrast, noise from seismic surveys was not found to 
impact feeding behavior or exhalation rates while resting or diving in 
western gray whales off the coast of Russia (Yazvenko et al., 2007; 
Gailey et al., 2007).
    Humpback whales showed avoidance behavior at ranges of five to 
eight km from a seismic array during observational studies and 
controlled exposure experiments in western Australia (McCauley, 1998; 
Todd et al., 1996). 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 and a shift to a higher incidence 
of net entanglement closer to the noise source.
    The strongest baleen whale response in any behavioral response 
study was observed in a minke whale in the 3S2 study, which responded 
at 146 dB re: 1 [micro]Pa by strongly avoiding the sound source 
(Kvadsheim et al., 2017; Sivle et al., 2015). Although the minke whale 
increased its swim speed, directional movement, and respiration rate, 
none of these were greater than rates observed in baseline behavior, 
and its dive behavior remained similar to baseline dives. A minke whale 
tagged in the Southern California behavioral response study also 
responded by increasing its directional movement, but maintained its 
speed and dive patterns, and so did not demonstrate as strong of a 
response (Kvadsheim et al., 2017). In addition, the 3S2 minke whale 
demonstrated some of the same avoidance behavior during the controlled 
ship approach with no sonar, indicating at least some of the response 
was to the vessel (Kvadsheim et al., 2017). 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, 
and increased again in the days after training was completed. 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. Similarly, minke 
whale detections made using Marine Acoustic Recording Instruments off 
Jacksonville, FL, were reduced or ceased altogether during periods of 
sonar use (Simeone et al., 2015; U.S. Department of the Navy, 2013b), 
especially with an increased ping rate (Charif et al., 2015).

[[Page 33951]]

Orientation
    A shift in an animal's resting state or an attentional change via 
an orienting response represent behaviors that would be considered mild 
disruptions if occurring alone. As previously mentioned, the responses 
may co-occur with other behaviors; for instance, an animal may 
initially orient toward a sound source, and then move away from it. 
Thus, any orienting response should be considered in context of other 
reactions that may occur.
Continued Pre-Disturbance Behavior and Habituation
    Under some circumstances, some of the individual marine mammals 
that are exposed to active sonar transmissions will continue their 
normal behavioral activities. In other circumstances, individual 
animals will respond to sonar transmissions at lower received levels 
and move to avoid additional exposure or exposures at higher received 
levels (Richardson et al., 1995).
    It is difficult to distinguish between animals that continue their 
pre-disturbance behavior without stress responses, animals that 
continue their behavior but experience stress responses (that is, 
animals that cope with disturbance), and animals that habituate to 
disturbance (that is, they may have experienced low-level stress 
responses initially, but those responses abated over time). Watkins 
(1986) reviewed data on the behavioral reactions of fin, humpback, 
right, and minke whales that were exposed to continuous, broadband low-
frequency shipping and industrial noise in Cape Cod Bay. He concluded 
that underwater sound was the primary cause of behavioral reactions in 
these species of whales and that the whales responded behaviorally to 
acoustic stimuli within their respective hearing ranges. Watkins also 
noted that whales showed the strongest behavioral reactions to sounds 
in the 15 Hz to 28 kHz range, although negative reactions (avoidance, 
interruptions in vocalizations, etc.) were generally associated with 
sounds that were either unexpected, too loud, suddenly louder or 
different, or perceived as being associated with a potential threat 
(such as an approaching ship on a collision course). In particular, 
whales seemed to react negatively when they were within 100 m of the 
source or when received levels increased suddenly in excess of 12 dB 
relative to ambient sounds. At other times, the whales ignored the 
source of the signal and all four species habituated to these sounds. 
Nevertheless, Watkins concluded that whales ignored most sounds in the 
background of ambient noise, including sounds from distant human 
activities even though these sounds may have had considerable energies 
at frequencies well within the whales' range of hearing. Further, he 
noted that of the whales observed, fin whales were the most sensitive 
of the four species, followed by humpback whales; right whales were the 
least likely to be disturbed and generally did not react to low-
amplitude engine noise. By the end of his period of study, Watkins 
(1986) concluded that fin and humpback whales had generally habituated 
to the continuous and broad-band noise of Cape Cod Bay while right 
whales did not appear to change their response. As mentioned above, 
animals that habituate to a particular disturbance may have experienced 
low-level stress responses initially, but those responses abated over 
time. In most cases, this likely means a lessened immediate potential 
effect from a disturbance. However, there is cause for concern where 
the habituation occurs in a potentially more harmful situation. For 
example, animals may become more vulnerable to vessel strikes once they 
habituate to vessel traffic (Swingle et al., 1993; Wiley et al., 1995).
    Aicken et al. (2005) monitored the behavioral responses of marine 
mammals to a new low-frequency active sonar system used by the British 
Navy (the United States Navy considers this to be a mid-frequency 
source as it operates at frequencies greater than 1,000 Hz). During 
those trials, fin whales, sperm whales, Sowerby's beaked whales, long-
finned pilot whales, Atlantic white-sided dolphins, and common 
bottlenose dolphins were observed and their vocalizations were 
recorded. These monitoring studies detected no evidence of behavioral 
responses that the investigators could attribute to exposure to the 
low-frequency active sonar during these trials.

Explosive Sources

    Underwater explosive detonations 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. 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.
    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. Blast effects are greatest at the gas-liquid 
interface (Landsberg, 2000). Gas-containing organs, particularly the 
lungs and gastrointestinal tract, are especially susceptible (Goertner, 
1982; Hill, 1978; Yelverton et al., 1973). 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 (small red or purple spots caused by bleeding in 
the skin), and slight hemorrhaging (Yelverton et al., 1973).
    Because the ears are the most sensitive to pressure, 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).

Further Potential Effects of Behavioral Disturbance on Marine Mammal 
Fitness

    The different ways that 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. There

[[Page 33952]]

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.
    One consequence of behavioral avoidance results in the altered 
energetic expenditure of marine mammals because energy is required to 
move and avoid surface vessels or the sound field associated with 
active sonar (Frid and Dill, 2002). Most animals can avoid that 
energetic cost by swimming away at slow speeds or speeds that minimize 
the cost of transport (Miksis-Olds, 2006), as has been demonstrated in 
Florida manatees (Miksis-Olds, 2006).
    Those energetic costs increase, however, when animals shift from a 
resting state, which is designed to conserve an animal's energy, to an 
active state that consumes energy the animal would have conserved had 
it not been disturbed. Marine mammals that have been disturbed by 
anthropogenic noise and vessel approaches are commonly reported to 
shift from resting to active behavioral states, which would imply that 
they incur an energy cost.
    Morete et al. (2007) reported that undisturbed humpback whale cows 
that were accompanied by their calves were frequently observed resting 
while their calves circled them (milling). When vessels approached, the 
amount of time cows and calves spent resting and milling, respectively, 
declined significantly. These results are similar to those reported by 
Scheidat et al. (2004) for the humpback whales they observed off the 
coast of Ecuador.
    Constantine and Brunton (2001) reported that bottlenose dolphins in 
the Bay of Islands, New Zealand engaged in resting behavior just 5 
percent of the time when vessels were within 300 m, compared with 83 
percent of the time when vessels were not present. However, Heenehan et 
al. (2016) report that results of a study of the response of Hawaiian 
spinner dolphins to human disturbance suggest that the key factor is 
not the sheer presence or magnitude of human activities, but rather the 
directed interactions and dolphin-focused activities that elicit 
responses from dolphins at rest. This information again illustrates the 
importance of context in regard to whether an animal will respond to a 
stimulus. Miksis-Olds (2006) and Miksis-Olds et al. (2005) reported 
that Florida manatees in Sarasota Bay, Florida, reduced the amount of 
time they spent milling and increased the amount of time they spent 
feeding when background noise levels increased. Although the acute 
costs of these changes in behavior are not likely to exceed an animal's 
ability to compensate, the chronic costs of these behavioral shifts are 
uncertain.
    Attention is the cognitive process of selectively concentrating on 
one aspect of an animal's environment while ignoring other things 
(Posner, 1994). Because animals (including humans) have limited 
cognitive resources, there is a limit to how much sensory information 
they can process at any time. The phenomenon called ``attentional 
capture'' occurs when a stimulus (usually a stimulus that an animal is 
not concentrating on or attending to) ``captures'' an animal's 
attention. This shift in attention can occur consciously or 
subconsciously (for example, when an animal hears sounds that it 
associates with the approach of a predator) and the shift in attention 
can be sudden (Dukas, 2002; van Rij, 2007). Once a stimulus has 
captured an animal's attention, the animal can respond by ignoring the 
stimulus, assuming a ``watch and wait'' posture, or treat the stimulus 
as a disturbance and respond accordingly, which includes scanning for 
the source of the stimulus or ``vigilance'' (Cowlishaw et al., 2004).
    Vigilance is normally an adaptive behavior that helps animals 
determine the presence or absence of predators, assess their distance 
from conspecifics, or to attend cues from prey (Bednekoff and Lima, 
1998; Treves, 2000). Despite those benefits, however, vigilance has a 
cost of time; when animals focus their attention on specific 
environmental cues, they are not attending to other activities such as 
foraging or resting. These effects have generally not been demonstrated 
for marine mammals, but studies involving fish and terrestrial animals 
have shown that increased vigilance may substantially reduce feeding 
rates (Saino, 1994; Beauchamp and Livoreil, 1997; Fritz et al., 2002; 
Purser and Radford, 2011). Animals will spend more time being vigilant, 
which may translate to less time foraging or resting, when disturbance 
stimuli approach them more directly, remain at closer distances, have a 
greater group size (e.g., multiple surface vessels), or when they co-
occur with times that an animal perceives increased risk (e.g., when 
they are giving birth or accompanied by a calf). An example of this 
concept with terrestrial species involved bighorn sheep and Dall's 
sheep, which dedicated more time being vigilant, and less time resting 
or foraging, when aircraft made direct approaches over them (Frid, 
2001; Stockwell et al., 1991). Vigilance has also been documented in 
pinnipeds at haul-out sites where resting may be disturbed when seals 
become alerted and/or flush into the water due to a variety of 
disturbances, which may be anthropogenic (noise and/or visual stimuli) 
or due to other natural causes such as other pinnipeds (Richardson et 
al., 1995; Southall et al., 2007; VanBlaricom, 2010; and Lozano and 
Hente, 2014).
    Chronic disturbance can cause population declines through reduction 
of fitness (e.g., decline in body condition) and subsequent reduction 
in reproductive success, survival, or both (e.g., Harrington and 
Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). For example, 
Madsen (1994) reported that pink-footed geese (Anser brachyrhynchus) in 
undisturbed habitat gained body mass and had about a 46 percent 
reproductive success rate compared with geese in disturbed habitat 
(being consistently scared off the fields on which they were foraging) 
which did not gain mass and had a 17 percent reproductive success rate. 
Similar reductions in reproductive success have been reported for mule 
deer (Odocoileus hemionus) disturbed by all-terrain vehicles (Yarmoloy 
et al., 1988), caribou (Rangifer tarandus caribou) disturbed by seismic 
exploration blasts (Bradshaw et al., 1998), and caribou disturbed by 
low-elevation military jet fights (Luick et al., 1996, Harrington and 
Veitch, 1992). Similarly, a study of elk (Cervus elaphus) that were 
disturbed experimentally by pedestrians concluded that the ratio of 
young to mothers was inversely related to disturbance rate (Phillips 
and Alldredge, 2000). However, Ridgway et al. (2006) reported that 
increased vigilance in bottlenose dolphins exposed to sound over a 
five-day period in open-air, open-water enclosures in

[[Page 33953]]

San Diego Bay did not cause any sleep deprivation or stress effects 
such as changes in cortisol or epinephrine levels.
    The primary mechanism by which increased vigilance and disturbance 
appear to affect the fitness of individual animals is by disrupting an 
animal's time budget and, as a result, reducing the time they might 
spend foraging and resting (which increases an animal's activity rate 
and energy demand while decreasing their caloric intake/energy). An 
example of this concept with terrestrial species involved a study of 
grizzly bears (Ursus horribilis) that reported that bears disturbed by 
hikers reduced their energy intake by an average of 12 kilocalories/min 
(50.2 x 103 kiloJoules/min), and spent energy fleeing or acting 
aggressively toward hikers (White et al., 1999).
    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 (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 an increased energy output of 3-4 
percent, which suggests that a management action based on avoiding 
interference with foraging might be particularly effective.
    On a related note, many animals perform vital functions, such as 
feeding, resting, traveling, and socializing, on a diel cycle (24-hr 
cycle). Behavioral reactions to noise exposure (such as disruption of 
critical life functions, displacement, or avoidance of important 
habitat) are more likely to be significant for fitness if they last 
more than one diel cycle or recur on subsequent days (Southall et al., 
2007). Consequently, a behavioral response lasting less than one day 
and not recurring on subsequent days is not considered particularly 
severe unless it could directly affect reproduction or survival 
(Southall et al., 2007). It is important to note the difference between 
behavioral reactions lasting or recurring over multiple days and 
anthropogenic activities lasting or recurring over multiple days. For 
example, just because at-sea exercises last for multiple days does not 
necessarily mean that individual animals will be either exposed to 
those activity-related stressors (i.e., sonar) for multiple days or 
further, exposed in a manner that would result in sustained multi-day 
substantive behavioral responses.
    Stone (2015a) reported data from at-sea observations during 1,196 
airgun surveys from 1994 to 2010. When large arrays of airguns 
(considered to be 500 in\3\ or more) were firing, lateral displacement, 
more localized avoidance, or other changes in behavior were evident for 
most odontocetes. However, significant responses to large arrays were 
found only for the minke whale and fin whale. Behavioral responses 
observed included changes in swimming or surfacing behavior, with 
indications that cetaceans remained near the water surface at these 
times. Cetaceans were recorded as feeding less often when large arrays 
were active. Monitoring of gray whales during an air gun survey 
included recording whale movements and respirations pre-, during-, and 
post-seismic survey (Gailey et al., 2016). Behavioral state and water 
depth were the best `natural' predictors of whale movements and 
respiration and, after considering natural variation, none of the 
response variables were significantly associated with survey or vessel 
sounds.
    In order to understand how the effects of activities may or may not 
impact species and stocks of marine mammals, it is necessary to 
understand not only what the likely disturbances are going to be, but 
how those disturbances may affect the reproductive success and 
survivorship of individuals, and then how those impacts to individuals 
translate to population-level effects. Following on the earlier work of 
a committee of the U.S. National Research Council (NRC, 2005), New et 
al. (2014), in an effort termed the Potential Consequences of 
Disturbance (PCoD), outline an updated conceptual model of the 
relationships linking disturbance to changes in behavior and 
physiology, health, vital rates, and population dynamics. 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). 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 whales, Ziphidae 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 are very specific models with very 
specific data requirements that 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 (sperm whale, Farmer et al. (2018); California sea 
lion, McHuron et al. (2018); and blue whale, Pirotta, et al. (2018a)). 
These models continue to add to refinement to the approaches to the 
population consequences of disturbance (PCOD) framework. Such models 
also help identify what data inputs require further investigation. 
Pirotta et al.

[[Page 33954]]

(2018b) provides a review of the PCOD framework with details on each 
step of the process and approaches to applying real data or simulations 
to achieve each step.

Stranding and Mortality

    The definition for a stranding under title IV of the MMPA is that 
(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 
MMPA section 410(3)). 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, ship 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 (Geraci et al., 
1976; Eaton, 1979, Odell et al., 1980; Best, 1982), 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 2017).
    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; DeVries et al., 2003; 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 (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., 2016b; 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 2006-2017, there were 19,430 cetacean 
strandings and 55,833 pinniped strandings (75,263 total) (P. Onens, 
NMFS, pers comm., 2019). 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 is in the Navy's 
Technical Report on Marine Mammal Strandings Associated with U.S. Navy 
Sonar Activities (U.S. Navy Marine Mammal Program & Space and Naval 
Warfare Systems Command Center Pacific, 2017).
    Worldwide, there have been several efforts to identify 
relationships between cetacean mass stranding events and military 
active sonar (Cox et al., 2006, Hildebrand, 2004; IWC, 2005; Taylor et 
al., 2004). For example, based on a review of mass stranding events 
around the world consisting of two or more individuals of Cuvier's 
beaked whales, records from the International Whaling Commission (IWC) 
(2005) show that a quarter (9 of 41) were associated with concurrent 
naval patrol, explosion, maneuvers, or MFAS. 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 Cuvier's 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 Cuvier's 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 
(Phocoena phocoena) (Norman et al., 2004, Wright et al., 2013) and 
common dolphin (Delphinus delphis) (Jepson and Deaville 2009).

Strandings Associated With Impulsive Sound

Silver Strand
    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-yd (640.1 m) exclusion zone around the 
explosive charge, monitored by personnel in a safety boat and 
participants in a dive boat. Approximately five 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. 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 68 km north of the detonation), which might also have 
been related to this event. Association of the

[[Page 33955]]

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 U.S. 
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
    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.
Gulf of California, Mexico
    One stranding event was contemporaneous with and reasonably 
associated spatially with the use of seismic air guns. This event 
occurred in the Gulf of California, coincident with seismic reflection 
profiling by the R/V Maurice Ewing operated by Columbia University's 
Lamont-Doherty Earth Observatory and involved two Cuvier's beaked 
whales (Hildebrand, 2004). The vessel had been firing an array of 20 
air guns with a total volume of 8,500 in\3\ (Hildebrand, 2004; Taylor 
et al., 2004).

Strandings Associated With Active Sonar

    Over the past 21 years, there have been five stranding events 
coincident with U.S. Navy MF active sonar 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 & 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 mid-frequency active sonar 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 Rim of the Pacific (RIMPAC) exercises, between 150 and 
200 usually pelagic melon-headed whales occupied the shallow waters of 
Hanalei Bay, Kauai, 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 (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 multi-beam 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 mid-frequency active sonar 
use and a small 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 Cuvier's beaked whales stranded atypically (in both time and 
space) along a 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, 2005a). 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, 2005a). The robust condition of the animals, 
plus the

[[Page 33956]]

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 Cuvier's 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 
hrs 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/SQS-56, moved through the channel 
while emitting sonar pings approximately every 24 seconds. Of the 17 
cetaceans that stranded over a 36-hour period (Cuvier's beaked whales, 
Blainville's beaked whales, minke whales, and a spotted dolphin), seven 
animals died on the beach (five Cuvier's beaked whales, one 
Blainville's beaked whale, and the 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, ship 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 Cuvier's beaked whales were found 
atypically 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 (Woods Hole 
Oceanographic Institution, 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 post mortem 
(Woods Hole Oceanographic Institution, 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 intercochlear 
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 (Woods Hole 
Oceanographic Institution, 2005). 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)

[[Page 33957]]

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 Cuvier's beaked whales, one Blainville's beaked whale, and 
one Gervais' beaked whale were necropsied, 6 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 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, Kauai, Hawaii for over 28 
hrs. Attendees of a canoe blessing observed the animals entering the 
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 the Bay on the afternoon 
of July 4, 2004, and was found dead in the 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 the 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 et 
al. (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 event was spatially and temporally correlated with 
RIMPAC. Official sonar training and tracking exercises in the Pacific 
Missile Range Facility (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 nine 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'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 the 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 bay. If the animals responded 
negatively to these signals, it may have contributed to their continued 
presence in the 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

[[Page 33958]]

use, the animals were herded out of the 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 Kauai; (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 the bay.
    A separate event involving melon-headed whales and rough-toothed 
dolphins took place over the same period of time in the Northern 
Mariana 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 et 
al., 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 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 
Cuvier's 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).

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

[[Page 33959]]

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. (2005) 
found that slow ascent rates from deep dives and long periods of time 
spent within 50 m of the surface were typical for both Cuvier's 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 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 mid-frequency active sonar 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 (such as 
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 (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. 
(2001) 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 2 km) and long (as long as 90 
minutes) foraging dives; (2) relatively slow, controlled ascents; and 
(3) a series of ``bounce'' dives between 100 and 400 m in depth (see 
also 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 72 
m for Cuvier's beaked whale), perhaps as a consequence of an extended 
avoidance reaction 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; Fern[aacute]ndez et al., 2012) 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., 2007). 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.
    If marine mammals respond to a Navy 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 Navy vessels are approaching them directly, because a direct 
approach may convey detection and intent to capture (Burger and 
Gochfeld, 1981, 1990; Cooper, 1997, 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 Dall's sheep (Ovis dalli dalli) 
(Frid 2001a, b), ringed seals (Phoca hispida) (Born et al., 1999), 
Pacific brant (Branta bernic 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 Acoustically-Induced Bubble Formation Due 
to Sonars and Other Pressure-related 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 reactions 
(such as atypical diving behavior) that secondarily cause bubble 
formation and tissue damage; and (5) the extent the post mortem 
artifacts introduced by decomposition before sampling, handling, 
freezing, or necropsy procedures affect interpretation of observed 
lesions.

Strandings in the NWTT Study Area

    Stranded marine mammals are reported along the entire western coast 
of the United States each year. Marine mammals strand due to natural or

[[Page 33960]]

anthropogenic causes; 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., 2017b; Helker 
et al., 2017; National Marine Fisheries Service, 2016). Stranding 
events that are associated with active UMEs on the Northwest Coast of 
the United States (inclusive of the NWTT Study Area) were previously 
discussed in the Description of Marine Mammals and Their Habitat in the 
Area of the Specified Activities section.
    From 2007-2016, 43,125 marine mammal strandings were confirmed by 
the West Coast Marine Mammal Stranding Network including 33,569 in 
California (including areas outside the NWTT Study Area), 3,776 in 
Oregon, and 5,780 in Washington (10 year Data Summary Report, West 
Coast Marine Mammal Stranding Network 2017). The most common marine 
mammal to strand in the NWTT Study Area was pinnipeds, which comprise 
94 percent of strandings in California, 90 percent of strandings in 
Oregon, and 89 percent of strandings in Washington. The next most 
common group was odontocetes, with harbor porpoises being the most 
common species. Gray whales were reported to be the most common large 
whale species to strand on the U.S. West Coast in all states. Where 
evidence of human interaction can be determined (9 percent as reported 
in the 10-year summary), the most common source of interaction on the 
U.S. West Coast was fishery interaction for pinnipeds, small cetaceans 
and large whales. The Behm Canal portion of the Study Area is a very 
small portion of the Southeast Regional Subarea of the Alaska Marine 
Mammal Stranding Network. A 10-year summary report is not available in 
this region however, in 2019 there were 40 confirmed strandings in the 
entire Southeast Regional Subarea, and 30 of these strandings were 
harbor seals or Steller sea lions.
    One stranding event has been investigated for a possible link to 
Navy activities in the NWTT Study Area. Between May 2 and June 2, 2003, 
approximately 16 strandings involving 15 harbor porpoises and one 
Dall's porpoise in the Eastern Strait of Juan de Fuca and Haro Strait 
were reported to the Northwest Marine Mammal Stranding Network. Given 
that the USS SHOUP was known to have operated sonar in the Haro strait 
on May 5, 2003, and that behavioral reactions of killer whales were 
possibly linked to these sonar operations, NMFS undertook an analysis 
of whether sonar caused the strandings of the porpoises (National 
Marine Fisheries Service, 2005). NMFS determined that the 2003 
strandings and similar harbor porpoise strandings over the following 
years were normal given a number of factors as described in Huggins et 
al. (2015). The 2015 NWTT FEIS/OEIS includes a comprehensive review of 
all strandings and the events involving the USS SHOUP on May 5, 2003. 
Additional information on this event is available in the Navy's 
Technical Report on Marine Mammal Strandings Associated with U.S. Navy 
Sonar Activities (U.S. Department of the Navy, 2017b). In the years 
since the SHOUP incident, annual numbers of stranded porpoises have 
been comparable (and sometimes higher) and have also shown similar 
causes of death (when determinable) to the causes of death noted in the 
SHOUP investigation (Huggins et al., 2015).

Marine Mammal Habitat

    The Navy's 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 2019 NWTT DSEIS/OEIS and was determined by the Navy to have no 
effect on marine mammal habitat. Based on the information below and the 
supporting information included in the 2019 NWTT DSEIS/OEIS, NMFS has 
determined that the proposed training and training 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 reaction 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 (pressure-
related injuries), and mortality.
    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) (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 Navy 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.

[[Page 33961]]

    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 (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 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 Navy 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, Navy 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 & 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 mid-frequency active sonar. 
Doksaeter et al. (2009; 2012) reported no behavioral responses to mid-
frequency naval sonar by Atlantic herring; specifically, no escape 
reactions (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. (2014) 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 reactions 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 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.
    For fishes exposed to Navy 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 are 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.

[[Page 33962]]

Long-term consequences for fish populations, including key prey species 
within the NWTT Study Area, would not be expected.
    Vessels and in-water devices do not normally collide with adult 
fish, 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 NWTT Study Area. Any 
isolated cases of a Navy 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 reactions 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., 2017b). 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. (2017b) 
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. (2017a) and 
Fewtrell and McCauley (2012) used are not similar and were much lower 
than typical Navy sources within the NWTT Study Area. Nor do the 
studies address the issue of individual displacement outside of a zone 
of impact when exposed to sound. 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.
    Explosions could 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 NWTT 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 recent 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 airgun 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 1.2 km. In 
order to have significant impacts on r-selected species such as 
plankton, the spatial or temporal scale of impact must be large in 
comparison with the ecosystem concerned (McCauley et al., 2017). 
Therefore, 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

[[Page 33963]]

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 (Hawkins et al., 2014). 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 NWTT 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 
(communication during feeding, mating, and other social activities), 
other animals (finding prey or avoiding predators), and the physical 
environment (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 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 (as in the use of air gun arrays) or for Navy training and 
testing purposes (as in the use of sonar and explosives and other 
acoustic sources). Anthropogenic noise varies widely in its frequency, 
content, duration, and loudness, and these characteristics greatly 
influence the potential habitat-mediated effects to marine mammals 
(please also see the previous discussion on ``Masking''), 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; Francis and Barber, 2013; 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., 
2014; 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 NWTT Study 
Area is temporary and transitory. Any anthropogenic noise attributed to 
training and testing activities in the NWTT 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 water quality 
constituents into the water column. Based on the analysis of the 2019 
NWTT DSEIS/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 in (0.15-0.3 m) away 
from degrading ordnance, the concentrations of these compounds

[[Page 33964]]

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 Navy within the NWTT 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 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 could occur or the maximum amount that is reasonably likely 
to occur, depending on the type of take and the methods used to 
estimate it, as described in detail below. NMFS coordinated closely 
with the Navy in the development of their incidental take application, 
and preliminarily agrees that the methods the Navy has put forth 
described herein to estimate take (including the model, thresholds, and 
density estimates), and the resulting numbers estimated for 
authorization, are appropriate and based on the best available science.
    Takes would be predominantly in the form of harassment, but a small 
number of mortalities are also possible. For a military readiness 
activity, the MMPA defines ``harassment'' as (i) 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 (ii) 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).
    Proposed authorized takes would primarily be in the form of Level B 
harassment, as use of the acoustic and explosive sources (i.e., sonar 
and explosives) is most likely to result in the 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 disruption) or TTS for 
marine mammals. 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 training and testing activities. Lastly, no more 
than three serious injuries or mortalities total (over the seven-year 
period) of large whales could potentially occur through vessel 
collisions. 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 
ship strike (and the associated serious injury or mortality) would 
occur.
    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 
will be taken by Level B harassment (in this case, as defined in the 
military readiness definition of Level B harassment included above) or 
incur some degree of temporary or permanent hearing impairment; (2) the 
area or volume of water that will 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 
experience a disruption in behavior patterns to a point where they are 
abandoned or significantly altered, or to incur TTS (equated to Level B 
harassment) or PTS of some degree (equated to Level A harassment). 
Thresholds have also been developed to identify the pressure levels 
above which animals may incur non-auditory injury from exposure to 
pressure waves from explosive detonation.
    Despite the quickly 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 
behavioral Level B 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 conservative 
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 Level B 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 Level B harassment thresholds are the most 
appropriate method for predicting behavioral Level B harassment given 
the best available science and the associated uncertainty.
Hearing Impairment (TTS/PTS) and Tissue Damage and Mortality
    NMFS' Acoustic Technical Guidance (NMFS, 2018) identifies dual 
criteria to assess auditory injury (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 Acoustic Technical Guidance also 
identifies criteria to predict TTS, which is not considered injury and 
falls into the Level B harassment category. The Navy's planned activity 
includes the use of non-impulsive (sonar) and impulsive (explosives) 
sources.
    These thresholds (Tables 10 and 11) were developed by compiling and 
synthesizing the best available science and soliciting input multiple 
times from both the public and peer reviewers. The references, 
analysis, and methodology used in the development of the thresholds are 
described in Acoustic Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/
marine-mammal-acoustic-technical-guidance.

[[Page 33965]]



 Table 10--Acoustic Thresholds Identifying the Onset of TTS and PTS for
        Non-Impulsive Sound Sources by Functional Hearing Groups
------------------------------------------------------------------------
                                                Non-impulsive
                                   -------------------------------------
     Functional hearing group       TTS threshold SEL  PTS threshold SEL
                                        (weighted)         (weighted)
------------------------------------------------------------------------
Low-Frequency Cetaceans...........                179                199
Mid-Frequency Cetaceans...........                178                198
High-Frequency Cetaceans..........                153                173
Phocid Pinnipeds (Underwater).....                181                201
Otarid Pinnipeds (Underwater).....                199                219
------------------------------------------------------------------------
Note: SEL thresholds in dB re: 1 [mu]Pa\2\s.

    Based on the best available science, the Navy (in coordination with 
NMFS) used the acoustic and pressure thresholds indicated in Table 11 
to predict the onset of TTS, PTS, tissue damage, and mortality for 
explosives (impulsive) and other impulsive sound sources.

                         Table 11--Onset of TTS, PTS, Tissue Damage, and Mortality thresholds for Marine Mammals for Explosives
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Weighted onset      Weighted  onset   Mean onset  slight  Mean onset  slight      Mean onset
    Functional hearing group            Species             TTS \1\               PTS          GI  tract injury      lung  injury          mortality
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-frequency cetaceans.........  All mysticetes....  168 dB SEL or 213   183 dB SEL or 219   237 dB Peak SPL...  Equation 1........  Equation 2.
                                                       dB Peak SPL.        dB Peak SPL.
Mid-frequency cetaceans.........  Most delphinids,    170 dB SEL or 224   185 dB SEL or 230   237 dB Peak SPL...
                                   medium and large    dB Peak SPL.        dB Peak SPL.
                                   toothed whales.
High-frequency cetaceans........  Porpoises and       140 dB SEL or 196   155 dB SEL or 202   237 dB Peak SPL...
                                   Kogia spp.          dB Peak SPL.        dB Peak SPL.
Phocidae........................  Harbor seal,        170 dB SEL or 212   185 dB SEL or 218   237 dB Peak SPL...
                                   Hawaiian monk       dB Peak SPL.        dB Peak SPL.
                                   seal, Northern
                                   elephant seal.
Otariidae.......................  California sea      188 dB SEL or 226   203 dB SEL or 232   237 dB Peak SPL...
                                   lion, Guadalupe     dB Peak SPL.        dB Peak SPL.
                                   fur seal,
                                   Northern fur seal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
Equation 1: 47.5M1/3 (1+[DRm/10.1])1/6 Pa-sec.
Equation 2: 103M1/3 (1+[DRm/10.1])1/6 Pa-sec.
M = mass of the animals in kg.
DRm = depth of the receiver (animal) in meters.
SPL = sound pressure level.
\1\ Peak thresholds are unweighted.

    The criteria used to assess the onset of TTS and PTS due to 
exposure to sonars (non-impulsive, see Table 10 above) are discussed 
further in the Navy's rulemaking/LOA application (see Hearing Loss from 
Sonar and Other Transducers in Chapter 6, Section 6.4.2.1, Methods for 
Analyzing Impacts from Sonars and Other Transducers). Refer to the 
``Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects 
Analysis (Phase III)'' report (U.S. Department of the Navy, 2017c) for 
detailed information on how the criteria and thresholds were derived. 
Non-auditory injury (i.e., other than PTS) and mortality from sonar and 
other transducers is so unlikely as to be discountable under normal 
conditions for the reasons explained under the Potential Effects of 
Specified Activities on Marine Mammals and Their Habitat section--
Acoustically Mediated Bubble Growth and other Pressure-related Injury 
and is therefore not considered further in this analysis.
Behavioral Harassment
    Though significantly driven by received level, the onset of Level B 
harassment by behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source (e.g., frequency, predictability, duty cycle), the environment 
(e.g., bathymetry), and the receiving animals (hearing, motivation, 
experience, demography, behavioral context) and can be difficult to 
predict (Ellison et al., 2011; Southall et al., 2007). Based on what 
the available science indicates and the practical need to use 
thresholds based on a factor, or factors, that are both predictable and 
measurable for most activities, NMFS uses generalized acoustic 
thresholds based primarily on received level (and distance in some 
cases) to estimate the onset of Level B behavioral harassment.

Sonar

    As noted above, the Navy coordinated with NMFS to develop Level B 
behavioral harassment thresholds specific to their military readiness 
activities utilizing active sonar. These behavioral response thresholds 
are used to estimate the number of animals that

[[Page 33966]]

may exhibit a behavioral response that rises to the level of a take 
when exposed to sonar and other transducers. The way the criteria were 
derived is discussed in detail in the ``Criteria and Thresholds for 
U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)'' report 
(U.S. Department of the Navy, 2017c). Developing the Level B harassment 
behavioral 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. 
NMFS has carefully reviewed the Navy's Level B behavioral thresholds 
and establishment of 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 sonar and 
other transducers and for calculating take and to support the 
determinations made in this proposed rule.
    As discussed above, marine mammal responses to sound (some of which 
are considered disturbances that rise to the level of a take) 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 
that there is support for considering alternative approaches for 
estimating Level B behavioral harassment. Although the statutory 
definition of Level B harassment for military readiness activities 
means that a natural behavior pattern of a marine mammal is 
significantly altered or abandoned, the current state of science for 
determining those thresholds is somewhat unsettled.
    In its analysis of impacts associated with sonar acoustic sources 
(which was coordinated with NMFS), the Navy used an updated 
conservative approach that likely overestimates the number of takes by 
Level B harassment due to behavioral disturbance and response. Many of 
the behavioral responses identified using the Navy's quantitative 
analysis are most likely to be of moderate severity as described in the 
Southall et al. (2007) 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 
Navy's quantitative analysis, many reactions are predicted from 
exposure to sound that may exceed an animal's Level B behavioral 
harassment threshold for only a single exposure (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.'' The Navy and NMFS have used the best available science to 
address the challenging differentiation between significant and non-
significant behavioral reactions (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 reactions as take), which 
likely results in some degree of overestimation of behavioral Level B 
harassment. We consider application of this behavioral Level B 
harassment threshold, 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). 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.
    In the Navy's acoustic impact analyses during Phase II (the 
previous phase of Navy testing and training, 2013-2018, see also Navy's 
``Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects 
Analysis Technical Report'', 2012), the likelihood of behavioral Level 
B harassment in response to sonar and other transducers was based on a 
probabilistic function (termed a behavioral response function--BRF), 
that related the likelihood (i.e., probability) of a behavioral 
response (at the level of a Level B harassment) to the received SPL. 
The BRF was used to estimate the percentage of an exposed population 
that is likely to exhibit Level B harassment due to altered behaviors 
or behavioral disturbance at a given received SPL. This BRF relied on 
the assumption that sound poses a negligible risk to marine mammals if 
they are exposed to SPL below a certain ``basement'' value. Above the 
basement exposure SPL, the probability of a response increased with 
increasing SPL. Two BRFs were used in Navy acoustic impact analyses: 
BRF1 for mysticetes and BRF2 for other species. BRFs were not used for 
beaked whales during Phase II analyses. Instead, a step function at an 
SPL of 140 dB re: 1 [mu]Pa was used for beaked whales as the threshold 
to predict Level B harassment by behavioral disturbance.
    Developing the behavioral Level B harassment criteria for Phase III 
(the current phase of Navy training and testing activities) involved 
multiple steps: all available behavioral response studies conducted 
both in the field and on captive animals were examined to understand 
the breadth of behavioral responses of marine mammals to sonar and 
other transducers (See also Navy's ``Criteria and Thresholds for U.S. 
Navy Acoustic and Explosive Effects Analysis (Phase III) Technical 
Report'', 2017). Six behavioral response field studies with 
observations of 14 different marine mammal species reactions to sonar 
or sonar-like signals and 6 captive animal behavioral studies with 
observations of 8 different species reactions to sonar or sonar-like 
signals were used to provide a robust data set for the derivation of 
the Navy's Phase III marine mammal behavioral response criteria. All 
behavioral response research that has been published since the 
derivation of the Navy's Phase III criteria (c.a. December 2016) has 
been examined and is consistent with the current behavioral response 
functions. Marine mammal species were placed into behavioral criteria 
groups based on their known or suspected behavioral sensitivities to 
sound. In most cases these divisions were driven by taxonomic 
classifications (e.g., mysticetes, pinnipeds). The data from the 
behavioral studies were analyzed by looking for significant responses, 
or lack thereof, for each experimental session.
    The Navy used cutoff distances beyond which the potential of 
significant behavioral responses (and therefore Level B harassment) is 
considered to be unlikely (see Table 12 below). These distances were 
determined by examining all available published field observations of 
behavioral reactions to sonar or sonar-like signals that included the 
distance between the sound source and the marine mammal. The longest 
distance, rounded up to the nearest 5-km increment, was chosen as the 
cutoff distance for each behavioral criteria group (i.e. odontocetes, 
mysticetes, and beaked whales). For animals within the cutoff distance, 
behavioral response functions for each behavioral criteria group based 
on a received SPL as presented in Chapter 6, Section 6.4.2.1 (Methods 
for Analyzing Impacts from Sonars and other Transducers) of the Navy's 
rulemaking/LOA application were used to predict the probability of

[[Page 33967]]

a potential significant behavioral response. For training and testing 
events that contain multiple platforms or tactical sonar sources that 
exceed 215 dB re: 1 [mu]Pa at 1 m, this cutoff distance is 
substantially increased (i.e., doubled) from values derived from the 
literature. The use of multiple platforms and intense sound sources are 
factors that probably increase responsiveness in marine mammals overall 
(however, we note that helicopter dipping sonars were considered in the 
intense sound source group, despite lower source levels, because of 
data indicating that marine mammals are sometimes more responsive to 
the less predictable employment of this source). There are currently 
few behavioral observations under these circumstances; therefore, the 
Navy conservatively predicted significant behavioral responses that 
would rise to Level B harassment at farther ranges than shown in Table 
12, versus less intense events.

  Table 12--Cutoff Distances for Moderate Source Level, Single Platform
   Training and Testing Events and for All Other Events With Multiple
   Platforms or Sonar With Source Levels at or Exceeding 215 dB re: 1
                            [micro]Pa at 1 m.
------------------------------------------------------------------------
                                           Moderate  SL/
                                              single      High  SL/multi-
             Criteria group                  platform         platform
                                              cutoff          cutoff
                                           distance (km)  distance  (km)
------------------------------------------------------------------------
Odontocetes.............................              10              20
Pinnipeds...............................               5              10
Mysticetes..............................              10              20
Beaked Whales...........................              25              50
Harbor Porpoise.........................              20              40
------------------------------------------------------------------------
Notes: dB re: 1 [mu]Pa at 1 m = decibels referenced to 1 micropascal at
  1 meter, km = kilometer, SL = source level.

    The range to received sound levels in 6-dB steps from five 
representative sonar bins and the percentage of animals that may be 
taken by Level B harassment under each behavioral response function are 
shown in Tables 13 through 17. Cells are shaded if the mean range value 
for the specified received level exceeds the distance cutoff range for 
a particular hearing group and therefore are not included in the 
estimated take. See Chapter 6, Section 6.4.2.1 (Methods for Analyzing 
Impacts from Sonars and Other Transducers) of the Navy's rulemaking/LOA 
application for further details on the derivation and use of the 
behavioral response functions, thresholds, and the cutoff distances to 
identify takes by Level B harassment, which were coordinated with NMFS. 
As noted previously, NMFS carefully reviewed, and contributed to, the 
Navy's proposed behavioral Level B harassment thresholds and cutoff 
distances for each behavioral criteria group, and agrees that these 
methods represent the best available science at this time for 
determining impacts to marine mammals from sonar and other transducers.
    Table 13 illustrates the maximum likely percentage of exposed 
individuals taken at the indicated received level and associated range 
(in which marine mammals would be reasonably expected to experience a 
disruption in behavior patterns to a point where they are abandoned or 
significantly altered) for low-frequency active sonar (LFAS).
BILLING CODE 3510-22-P

[[Page 33968]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.014

    Tables 14 through 16 identify the maximum likely percentage of 
exposed individuals taken at the indicated received level and 
associated range for mid-frequency active sonar (MFAS).

[[Page 33969]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.003


[[Page 33970]]


[GRAPHIC] [TIFF OMITTED] TP02JN20.004


[[Page 33971]]


[GRAPHIC] [TIFF OMITTED] TP02JN20.005

    Table 17 identifies the maximum likely percentage of exposed 
individuals taken at the indicated received level and associated range 
for high-frequency active sonar (HFAS).

[[Page 33972]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.006

BILLING CODE 3510-22-C
Explosives
    Phase III explosive criteria for behavioral Level B harassment 
thresholds for marine mammals is the functional hearing groups' TTS 
onset threshold (in SEL) minus 5 dB (see Table 18 below and Table 11 
for the TTS thresholds for explosives) for events that contain multiple 
impulses from explosives underwater. This was the same approach as 
taken in Phase II for explosive analysis. See the ``Criteria and 
Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase 
III)'' report (U.S. Department of the Navy, 2017c) for detailed 
information on how the criteria and thresholds were derived. NMFS 
continues to concur that this approach represents the best available 
science for determining impacts to marine mammals from explosives.

  Table 18--Behavioral Level B Harassment Thresholds for Explosives for
                             Marine Mammals
------------------------------------------------------------------------
                                    Functional hearing          SEL
             Medium                       group             (weighted)
------------------------------------------------------------------------
Underwater.....................  Low-frequency cetaceans             163
Underwater.....................  Mid-frequency cetaceans             165
Underwater.....................  High-frequency                      135
                                  cetaceans.
Underwater.....................  Phocids................             165
Underwater.....................  Otariids...............             183
------------------------------------------------------------------------
Note: Weighted SEL thresholds in dB re: 1 [mu]Pa\2\s underwater.

Navy's Acoustic Effects Model
    The Navy's Acoustic Effects Model calculates sound energy 
propagation from sonar and other transducers and explosives during 
naval activities and the sound received by animat dosimeters. Animat 
dosimeters are virtual representations of marine mammals distributed in 
the area around the modeled naval activity and each dosimeter records 
its individual sound ``dose.'' The model bases the distribution of 
animats over the NWTT Study Area on the density values in the Navy 
Marine Species Density Database 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

[[Page 33973]]

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.
    Assumptions in the Navy model intentionally err on the side of 
overestimation when there are unknowns. Naval activities are modeled as 
though they would occur regardless of proximity to marine mammals, 
meaning that no mitigation is considered (i.e., no power down or shut 
down modeled) and without any avoidance of the activity by the animal. 
The final step of the quantitative analysis of acoustic effects is to 
consider the implementation of mitigation and the possibility that 
marine mammals would avoid continued or repeated sound exposures. For 
more information on this process, see the discussion in the Take 
Requests subsection 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 impacts caused by individual training and 
testing exercises. 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 the Navy's Acoustic 
Effects Model is provided in the technical report ``Quantifying 
Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and 
Analytical Approach for Phase III Training and Testing'' (U.S. 
Department of the Navy, 2018).
Sonar and Other Transducers and Explosives
Range to Effects
    The following section provides range to effects for sonar and other 
active acoustic sources as well as explosives to specific acoustic 
thresholds determined using the Navy Acoustic Effects Model. 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
    The ranges to received sound levels in 6-dB steps from five 
representative sonar bins and the percentage of the total number of 
animals that may exhibit a significant behavioral response (and 
therefore Level B harassment) under each behavioral response function 
are shown in Tables 13 through 17 above. See Chapter 6, Section 6.4.2.1 
(Methods for Analyzing Impacts from Sonars and Other Transducers) of 
the Navy's rulemaking/LOA application for additional details on the 
derivation and use of the behavioral response functions, thresholds, 
and the cutoff distances that are used to identify Level B behavioral 
harassment.
    The ranges to PTS for five representative sonar systems for an 
exposure of 30 seconds is shown in Table 19 relative to the marine 
mammal's functional hearing group. This period (30 seconds) was chosen 
based on examining the maximum amount of time a marine mammal would 
realistically be exposed to levels that could cause the onset of PTS 
based on platform (e.g., ship) speed and a nominal animal swim speed of 
approximately 1.5 m per second. The ranges provided in the table 
include the average range to PTS, as well as the range from the minimum 
to the maximum distance at which PTS is possible for each hearing 
group.

           Table 19--Range to Permanent Threshold Shift (Meters) for Five Representative Sonar Systems
----------------------------------------------------------------------------------------------------------------
                                                 Approximate PTS (30 seconds) ranges (meters) \1\
          Hearing group          -------------------------------------------------------------------------------
                                   Sonar bin HF4   Sonar bin LF4   Sonar bin MF1   Sonar bin MF4   Sonar bin MF5
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........      38 (22-85)         0 (0-0)    195 (80-330)      30 (30-40)        9 (8-11)
Low-frequency cetaceans.........         0 (0-0)         2 (1-3)     67 (60-110)      15 (15-17)         0 (0-0)
Mid-frequency cetaceans.........         1 (0-3)         0 (0-0)      16 (16-19)         3 (3-3)         0 (0-0)
Otariids........................         0 (0-0)         0 (0-0)         6 (6-6)         0 (0-0)         0 (0-0)
Phocids.........................         0 (0-0)         0 (0-0)      46 (45-75)      11 (11-12)         0 (0-0)
----------------------------------------------------------------------------------------------------------------
\1\ PTS ranges extend from the sonar or other transducer sound source to the indicated distance. The average
  range to PTS is provided as well as the range from the estimated minimum to the maximum range to PTS in
  parentheses.
Notes: HF = high-frequency, LF = low-frequency, MF = mid-frequency, PTS = permanent threshold shift.

    The tables below illustrate the range to TTS for 1, 30, 60, and 120 
seconds from five representative sonar systems (see Tables 20 through 
24).

     Table 20--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin LF4 Over a Representative Range of
                                     Environments Within the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                Approximate TTS ranges (meters) \1\
                                                 ---------------------------------------------------------------
                  Hearing group                                            Sonar bin LF4
                                                 ---------------------------------------------------------------
                                                     1 second       30 seconds      60 seconds      120 seconds
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........................         0 (0-0)         0 (0-0)         0 (0-0)         1 (0-1)

[[Page 33974]]

 
Low-frequency cetaceans.........................      22 (19-30)     32 (25-230)     41 (30-230)     61 (45-100)
Mid-frequency cetaceans.........................         0 (0-0)         0 (0-0)         0 (0-0)         0 (0-0)
Otariids........................................         0 (0-0)         0 (0-0)         0 (0-0)         0 (0-0)
Phocids.........................................         2 (1-3)         4 (3-4)         4 (4-5)         7 (6-9)
----------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone
  in which animals are expected to suffer TTS extends from onset-PTS to the distance indicated. The average
  range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in
  parentheses.
Notes: HF = high-frequency, TTS = temporary threshold shift.


     Table 21--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF1 Over a Representative Range of
                                     Environments Within the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                Approximate TTS ranges (meters) \1\
                                                 ---------------------------------------------------------------
                  Hearing group                                            Sonar bin MF1
                                                 ---------------------------------------------------------------
                                                     1 second       30 seconds      60 seconds      120 seconds
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........................      2,466 (80-      2,466 (80-      3,140 (80-      3,740 (80-
                                                          6,275)          6,275)         10,275)         13,525)
Low-frequency cetaceans.........................      1,054 (80-      1,054 (80-      1,480 (80-      1,888 (80-
                                                          2,775)          2,775)          4,525)          5,275)
Mid-frequency cetaceans.........................    225 (80-380)    225 (80-380)    331 (80-525)    411 (80-700)
Otariids........................................     67 (60-110)     67 (60-110)    111 (80-170)    143 (80-250)
Phocids.........................................  768 (80-2,025)  768 (80-2,025)      1,145 (80-      1,388 (80-
                                                                                          3,275)          3,775)
----------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone
  in which animals are expected to suffer TTS extends from onset-PTS to the distance indicated. The average
  range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in
  parentheses. Ranges for 1 second and 30 second periods are identical for Bin MF1 because this system nominally
  pings every 50 seconds; therefore, these periods encompass only a single ping.
Notes: MF = mid-frequency, TTS = temporary threshold shift.


     Table 22--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF4 Over a Representative Range of
                                     Environments Within the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                           Approximate TTS ranges (meters) \1\
                                       -------------------------------------------------------------------------
             Hearing group                                            Sonar bin MF4
                                       -------------------------------------------------------------------------
                                           1 second       30 seconds      60 seconds           120 seconds
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans..............   279 (220-600)       647 (420-       878 (500-         1,205 (525-2,275)
                                                                1,275)          1,525)
Low-frequency cetaceans...............     87 (85-110)   176 (130-320)   265 (190-575)             477 (290-975)
Mid-frequency cetaceans...............      22 (22-25)      35 (35-45)      50 (45-55)                71 (70-85)
Otariids..............................         8 (8-8)      15 (15-17)      19 (19-23)                25 (25-30)
Phocids...............................      66 (65-80)   116 (110-200)   173 (150-300)             303 (240-675)
----------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone
  in which animals are expected to suffer TTS extends from onset-PTS to the distance indicated. The average
  range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in
  parentheses.
Notes: MF = mid-frequency, TTS = temporary threshold shift.


     Table 23--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin MF5 Over a Representative Range of
                                     Environments Within the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                Approximate TTS ranges (meters) \1\
                                                 ---------------------------------------------------------------
                  Hearing group                                            Sonar bin MF5
                                                 ---------------------------------------------------------------
                                                     1 second       30 seconds      60 seconds      120 seconds
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........................   115 (110-180)   115 (110-180)   174 (150-390)   292 (210-825)
Low-frequency cetaceans.........................      11 (10-13)      11 (10-13)      17 (16-19)      24 (23-25)
Mid-frequency cetaceans.........................         6 (0-9)         6 (0-9)      12 (11-14)      18 (17-22)
Otariids........................................         0 (0-0)         0 (0-0)         0 (0-0)         0 (0-0)

[[Page 33975]]

 
Phocids.........................................        9 (8-11)        9 (8-11)      15 (14-17)      22 (21-25)
----------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone
  in which animals are expected to suffer TTS extends from onset-PTS to the distance indicated. The average
  range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in
  parentheses.
Notes: MF = mid-frequency, TTS = temporary threshold shift.


     Table 24--Ranges to Temporary Threshold Shift (Meters) for Sonar Bin HF4 Over a Representative Range of
                                     Environments Within the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                                Approximate TTS Ranges (meters) \1\
                                                 ---------------------------------------------------------------
                  Hearing group                                            Sonar bin HF4
                                                 ---------------------------------------------------------------
                                                     1 second       30 seconds      60 seconds      120 seconds
----------------------------------------------------------------------------------------------------------------
High-frequency cetaceans........................    236 (60-675)    387 (60-875)  503 (60-1,025)  637 (60-1,275)
Low-frequency cetaceans.........................         2 (0-3)         3 (1-6)         5 (3-8)        8 (5-12)
Mid-frequency cetaceans.........................       12 (7-20)      21 (12-40)      29 (17-60)      43 (24-90)
Otariids........................................         0 (0-0)         0 (0-0)         0 (0-0)         1 (0-1)
Phocids.........................................         3 (0-5)        6 (4-10)        9 (5-15)       14 (8-25)
----------------------------------------------------------------------------------------------------------------
\1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone
  in which animals are expected to suffer TTS extends from onset-PTS to the distance indicated. The average
  range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in
  parentheses.
Notes: HF = high-frequency, TTS = temporary threshold shift.

Explosives
    The following section provides the range (distance) over which 
specific physiological or behavioral effects are expected to occur 
based on the explosive criteria (see Chapter 6, Section 6.5.2 (Impacts 
from Explosives) of the Navy's rulemaking/LOA application and the 
``Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects 
Analysis (Phase III)'' report (U.S. Department of the Navy, 2017c)) and 
the explosive propagation calculations from the Navy Acoustic Effects 
Model (see Chapter 6, Section 6.5.2.2 (Impact Ranges for Explosives) of 
the Navy's rulemaking/LOA application). The range to effects are shown 
for a range of explosive bins, from E1 (up to 0.25 lb net explosive 
weight) to E11 (greater than 500 lb to 650 lb net explosive weight) 
(Tables 25 through 31). 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, PTS, and non-auditory injury. NMFS has reviewed the range distance 
to effect data provided by the Navy 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 adequate 
mitigation ranges to avoid higher level effects, especially 
physiological effects to marine mammals. For additional information on 
how ranges to impacts from explosions were estimated, see the technical 
report ``Quantifying Acoustic Impacts on Marine Mammals and Sea 
Turtles: Methods and Analytical Approach for Phase III Training and 
Testing'' (U.S. Navy, 2018).
    Tables 25 through 29 show the minimum, average, and maximum ranges 
to onset of auditory and likely behavioral effects that rise to the 
level of Level B harassment for high-frequency cetaceans based on the 
developed thresholds. Ranges are provided for a representative source 
depth and cluster size (the number of rounds fired, or buoys dropped, 
within a very short duration) for each bin. 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. Ranges to non-auditory injury and mortality are shown 
in Tables 30 and 31, respectively.
    Table 25 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for high-frequency cetaceans based on the developed 
thresholds.

                  Table 25--SEL-Based Ranges to Onset PTS, Onset TTS, and Behavioral Reaction (in Meters) for High-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Range to effects for explosives: High-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Source depth
                     Bin                             (m)        Cluster size       Range to PTS (m)         Range to TTS (m)     Range to behavioral (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1...........................................             0.1               1            361 (350-370)      1,108 (1,000-1,275)      1,515 (1,025-2,025)
                                                                           18        1,002 (925-1,025)      2,404 (1,275-4,025)      3,053 (1,275-5,025)
E2...........................................             0.1               1            439 (420-450)      1,280 (1,025-1,775)      1,729 (1,025-2,525)

[[Page 33976]]

 
                                                                            5            826 (775-875)      1,953 (1,275-3,025)      2,560 (1,275-4,275)
E3...........................................              10               1        1,647 (160-3,525)       2,942 (160-10,275)       3,232 (160-12,275)
                                                                           12        3,140 (160-9,525)       3,804 (160-17,525)       3,944 (160-21,775)
                                                        18.25               1          684 (550-1,000)      2,583 (1,025-5,025)      4,217 (1,525-7,525)
                                                                           12      1,774 (1,025-3,775)     5,643 (1,775-10,025)     7,220 (2,025-13,275)
E4...........................................              10               2        1,390 (950-3,025)      5,250 (2,275-8,275)     7,004 (2,775-11,275)
                                                           30               2        1,437 (925-2,775)      4,481 (1,525-7,775)     5,872 (2,775-10,525)
                                                           70               2        1,304 (925-2,275)      3,845 (2,525-7,775)      5,272 (3,525-9,525)
                                                           90               2        1,534 (900-2,525)      5,115 (2,525-7,525)     6,840 (3,275-10,275)
E5...........................................             0.1               1          940 (850-1,025)      2,159 (1,275-3,275)      2,762 (1,275-4,275)
                                                                           20      1,930 (1,275-2,775)      4,281 (1,775-6,525)      5,176 (2,025-7,775)
E7...........................................              10               1      2,536 (1,275-3,775)     6,817 (2,775-11,025)     8,963 (3,525-14,275)
                                                           30               1      1,916 (1,025-4,275)     5,784 (2,775-10,525)     7,346 (2,775-12,025)
E8...........................................           45.75               1      1,938 (1,275-4,025)     4,919 (1,775-11,275)     5,965 (2,025-15,525)
E10..........................................             0.1               1      1,829 (1,025-2,775)      4,166 (1,775-6,025)      5,023 (2,025-7,525)
E11..........................................            91.4               1      3,245 (2,025-6,775)     6,459 (2,525-15,275)     7,632 (2,775-19,025)
                                                          200               1      3,745 (3,025-5,025)     7,116 (4,275-11,275)     8,727 (5,025-15,025)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (meters) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances (due to varying propagation
  environments), which are in parentheses.
Notes: PTS = permanent threshold shift, SEL = sound exposure level, TTS = temporary threshold shift.

    Table 26 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for low-frequency cetaceans based on the developed 
thresholds.

                   Table 26--SEL-Based Ranges to Onset PTS, Onset TTS, and Behavioral Reaction (in Meters) for Low-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Range to effects for explosives: Low-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Source depth                                                                       Range to behavioral
                     Bin                          (meters)      Cluster size    Range to PTS (meters)    Range to TTS (meters)           (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1...........................................             0.1               1               52 (50-55)            221 (120-250)            354 (160-420)
                                                                           18            177 (110-200)            656 (230-875)          836 (280-1,025)
E2...........................................             0.1               1               66 (55-70)            276 (140-320)            432 (180-525)
                                                                            5             128 (90-140)            512 (200-650)            735 (250-975)
E3...........................................              10               1            330 (160-550)        1,583 (160-4,025)        2,085 (160-7,525)
                                                                           12        1,177 (160-2,775)       2,546 (160-11,775)       2,954 (160-17,025)
                                                        18.25               1            198 (180-220)        1,019 (490-2,275)        1,715 (625-4,025)
                                                                           12          646 (390-1,025)        3,723 (800-9,025)     6,399 (1,025-46,525)
E4...........................................              10               2            462 (400-600)      3,743 (2,025-7,025)     6,292 (2,525-13,275)
                                                           30               2            527 (330-950)      3,253 (1,775-4,775)      5,540 (2,275-8,275)
                                                           70               2            490 (380-775)      3,026 (1,525-4,775)      5,274 (2,275-7,775)
                                                           90               2            401 (360-500)      3,041 (1,275-4,525)      5,399 (1,775-9,275)
E5...........................................             0.1               1            174 (100-260)            633 (220-850)          865 (270-1,275)
                                                                           20            550 (200-700)        1,352 (420-2,275)        2,036 (700-4,275)
E7...........................................              10               1        1,375 (875-2,525)     7,724 (3,025-15,025)    11,787 (4,525-25,275)
                                                           30               1        1,334 (675-2,025)     7,258 (2,775-11,025)    11,644 (4,525-24,275)
E8...........................................           45.75               1        1,227 (575-2,525)     3,921 (1,025-17,275)     7,961 (1,275-48,525)
E10..........................................             0.1               1            546 (200-700)        1,522 (440-5,275)       3,234 (850-30,525)
E11..........................................            91.4               1        2,537 (950-5,525)    11,249 (1,775-50,775)    37,926 (6,025-94,775)
                                                          200               1      2,541 (1,525-4,775)     7,407 (2,275-43,275)    42,916 (6,275-51,275)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (meters) is shown with the minimum and maximum distances due to varying propagation environments in parentheses. Values depict the
  range produced by SEL hearing threshold criteria levels.
Notes: PTS = permanent threshold shift, SEL = sound exposure level, TTS = temporary threshold shift.

    Table 27 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for mid-frequency cetaceans based on the developed 
thresholds.

[[Page 33977]]



                   Table 27--SEL-Based Ranges to Onset PTS, Onset TTS, and Behavioral Reaction (in Meters) for Mid-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Range to effects for explosives: Mid-frequency cetaceans \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                            Range to
                              Bin                                 Source depth    Cluster size      Range to PTS       Range to TTS        behavioral
                                                                    (meters)                          (meters)           (meters)           (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.............................................................             0.1               1         25 (25-25)      118 (110-120)      203 (190-210)
                                                                                             18        96 (90-100)      430 (410-440)      676 (600-700)
E2.............................................................             0.1               1         30 (30-30)      146 (140-150)      246 (230-250)
                                                                                              5         64 (60-65)      298 (290-300)      493 (470-500)
E3.............................................................              10               1        61 (50-100)      512 (160-750)    928 (160-2,025)
                                                                                             12      300 (160-625)  1,604 (160-3,525)  2,085 (160-5,525)
                                                                          18.25               1         40 (35-40)      199 (180-280)      368 (310-800)
                                                                                             12      127 (120-130)    709 (575-1,000)  1,122 (875-2,525)
E4.............................................................              10               2         73 (70-75)      445 (400-575)    765 (600-1,275)
                                                                             30               2         71 (65-90)    554 (320-1,025)    850 (525-1,775)
                                                                             70               2         63 (60-85)      382 (320-675)    815 (525-1,275)
                                                                             90               2         59 (55-85)      411 (310-900)    870 (525-1,275)
E5.............................................................             0.1               1         79 (75-80)      360 (350-370)      575 (525-600)
                                                                                             20      295 (280-300)    979 (800-1,275)  1,442 (925-1,775)
E7.............................................................              10               1      121 (110-130)    742 (575-1,275)  1,272 (875-2,275)
                                                                             30               1      111 (100-130)    826 (500-1,775)  1,327 (925-2,275)
E8.............................................................           45.75               1      133 (120-170)    817 (575-1,525)  1,298 (925-2,525)
E10............................................................             0.1               1      273 (260-280)    956 (775-1,025)  1,370 (900-1,775)
E11............................................................            91.4               1      242 (220-310)      1,547 (1,025-      2,387 (1,275-
                                                                                                                               3,025)             4,025)
                                                                            200               1      209 (200-300)      1,424 (1,025-      2,354 (1,525-
                                                                                                                               2,025)             3,775)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (meters) is shown with the minimum and maximum distances due to varying propagation environments in parentheses.
Note: PTS = permanent threshold shift, SEL = sound exposure level, TTS = temporary threshold shift.

    Table 28 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for otariid pinnipeds based on the developed thresholds.

                          Table 28--SEL-Based Ranges to Onset PTS, Onset TTS, and Behavioral Reaction (in Meters) for Otariids
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Range to effects for explosives: Otariids \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                            Range to
                              Bin                                 Source depth    Cluster size      Range to PTS       Range to TTS        behavioral
                                                                    (meters)                          (meters)           (meters)           (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1.............................................................             0.1               1            7 (7-8)         34 (30-35)         58 (55-60)
                                                                                             18         25 (25-25)      124 (120-130)      208 (200-210)
E2.............................................................             0.1               1           9 (9-10)         43 (40-45)         72 (70-75)
                                                                                              5         19 (19-20)         88 (85-90)      145 (140-150)
E3.............................................................              10               1         21 (18-25)      135 (120-210)      250 (160-370)
                                                                                             12        82 (75-100)      551 (160-875)    954 (160-2,025)
                                                                          18.25               1         15 (15-15)         91 (85-95)      155 (150-160)
                                                                                             12         53 (50-55)      293 (260-430)      528 (420-825)
E4.............................................................              10               2         30 (30-30)      175 (170-180)      312 (300-350)
                                                                             30               2         25 (25-25)      176 (160-250)      400 (290-750)
                                                                             70               2         26 (25-35)      148 (140-200)      291 (250-400)
                                                                             90               2         26 (25-35)      139 (130-190)      271 (250-360)
E5.............................................................             0.1               1         25 (24-25)      111 (110-120)      188 (180-190)
                                                                                             20         93 (90-95)      421 (390-440)      629 (550-725)
E7.............................................................              10               1         60 (60-60)      318 (300-360)      575 (500-775)
                                                                             30               1         53 (50-65)      376 (290-700)    742 (500-1,025)
E8.............................................................           45.75               1         55 (55-55)      387 (310-750)    763 (525-1,275)
E10............................................................             0.1               1         87 (85-90)      397 (370-410)      599 (525-675)
E11............................................................            91.4               1      100 (100-100)    775 (550-1,275)  1,531 (900-3,025)
                                                                            200               1        94 (90-100)      554 (525-700)  1,146 (900-1,525)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (meters) is shown with the minimum and maximum distances due to varying propagation environments in parentheses.
Notes: PTS = permanent threshold shift, SEL = sound exposure level, TTS = temporary threshold shift.

    Table 29 shows the minimum, average, and maximum ranges to onset of 
auditory and likely behavioral effects that rise to the level of Level 
B harassment for phocid pinnipeds based on the developed thresholds.

[[Page 33978]]



                           Table 29--SEL-Based Ranges to Onset PTS, Onset TTS, and Behavioral Reaction (in Meters) for Phocids
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Range to effects for explosives: Phocids \1\
---------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Source depth                                                                       Range to behavioral
                     Bin                          (meters)      Cluster size    Range to PTS (meters)    Range to TTS (meters)           (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1...........................................             0.1               1               47 (45-50)            219 (210-230)            366 (350-370)
                                                                           18            171 (160-180)            764 (725-800)      1,088 (1,025-1,275)
E2...........................................             0.1               1               59 (55-60)            273 (260-280)            454 (440-460)
                                                                            5            118 (110-120)            547 (525-550)            881 (825-925)
E3...........................................              10               1            185 (160-260)        1,144 (160-2,775)        1,655 (160-4,525)
                                                                           12          760 (160-1,525)        2,262 (160-8,025)       2,708 (160-12,025)
                                                        18.25               1            112 (110-120)            628 (500-950)        1,138 (875-2,525)
                                                                           12            389 (330-625)      2,248 (1,275-4,275)      4,630 (1,275-8,525)
E4...........................................              10               2            226 (220-240)        1,622 (950-3,275)      3,087 (1,775-5,775)
                                                           30               2            276 (200-600)      1,451 (1,025-2,275)      2,611 (1,775-4,275)
                                                           70               2            201 (180-280)      1,331 (1,025-1,775)      2,403 (1,525-3,525)
                                                           90               2            188 (170-270)        1,389 (975-2,025)      2,617 (1,775-3,775)
E5...........................................             0.1               1            151 (140-160)            685 (650-700)        1,002 (950-1,025)
                                                                           20            563 (550-575)      1,838 (1,275-2,275)      2,588 (1,525-3,525)
E7...........................................              10               1            405 (370-490)      3,185 (1,775-6,025)     5,314 (2,275-11,025)
                                                           30               1            517 (370-875)      2,740 (1,775-4,275)      4,685 (3,025-7,275)
E8...........................................           45.75               1          523 (390-1,025)      2,502 (1,525-6,025)     3,879 (2,025-10,275)
E10..........................................             0.1               1            522 (500-525)      1,800 (1,275-2,275)      2,470 (1,525-3,275)
E11..........................................            91.4               1        1,063 (675-2,275)     5,043 (2,775-10,525)     7,371 (3,275-18,025)
                                                          200               1            734 (675-850)      5,266 (3,525-9,025)     7,344 (5,025-12,775)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance (meters) is shown with the minimum and maximum distances due to varying propagation environments in parentheses.
Notes: PTS = permanent threshold shift, SEL = sound exposure level, TTS = temporary threshold shift.

    Table 30 shows the minimum, average, and maximum ranges due to 
varying propagation conditions to non-auditory injury as a function of 
animal mass and explosive bin (i.e., net explosive weight). Ranges to 
gastrointestinal tract injury typically exceed ranges to slight lung 
injury; therefore, the maximum range to effect is not mass-dependent. 
Animals within these water volumes 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 30--Ranges \1\ to Non-Auditory Injury (in Meters) for All Marine
                          Mammal Hearing Groups
------------------------------------------------------------------------
                                                           Range to non-
                                                             auditory
                           Bin                                injury
                                                           (meters) \1\
------------------------------------------------------------------------
E1......................................................      12 (11-13)
E2......................................................      16 (15-16)
E3......................................................      25 (25-45)
E4......................................................      31 (23-50)
E5......................................................      40 (40-40)
E7......................................................    104 (80-190)
E8......................................................   149 (130-210)
E10.....................................................   153 (100-400)
E11.....................................................   419 (350-725)
------------------------------------------------------------------------
\1\ Distances in meters (m). Average distance is shown with the minimum
  and maximum distances due to varying propagation environments in
  parentheses. Modeled ranges based on peak pressure for a single
  explosion generally exceed the modeled ranges based on impulse
  (related to animal mass and depth).

    Ranges to mortality, based on animal mass, are shown in Table 31 
below.

                     Table 31--Ranges \1\ to Mortality (in Meters) for All Marine Mammal Hearing Groups as a Function of Animal Mass
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Range to mortality (meters) for various animal mass intervals (kg) \1\
                           Bin                           -----------------------------------------------------------------------------------------------
                                                               10 kg          250 kg         1,000 kg        5,000 kg        25,000 kg       72,000 kg
--------------------------------------------------------------------------------------------------------------------------------------------------------
E1......................................................         3 (2-3)         1 (0-3)         0 (0-0)         0 (0-0)         0 (0-0)         0 (0-0)
E2......................................................         4 (3-5)         2 (1-3)         1 (0-1)         0 (0-0)         0 (0-0)         0 (0-0)
E3......................................................       10 (9-20)        5 (3-20)         2 (1-5)         0 (0-3)         0 (0-1)         0 (0-1)
E4......................................................      13 (11-19)        7 (4-13)         3 (2-4)         2 (1-3)         1 (1-1)         1 (0-1)
E5......................................................      13 (11-15)        7 (4-11)         3 (3-4)         2 (1-3)         1 (1-1)         1 (0-1)
E7......................................................      49 (40-80)      27 (15-60)      13 (10-20)        9 (5-12)         4 (4-6)         3 (2-4)
E8......................................................      65 (60-75)      34 (22-55)      17 (14-20)       11 (9-13)         6 (5-6)         5 (4-5)
E10.....................................................      43 (40-50)      25 (16-40)      13 (11-16)        9 (7-11)         5 (4-6)         4 (3-4)
E11.....................................................    185 (90-230)     90 (30-170)      40 (30-50)      28 (23-30)      15 (13-16)       11 (9-13)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Average distance to mortality (meters) is depicted above the minimum and maximum distances, which are in parentheses for each animal mass interval.
Notes: kg = kilogram.


[[Page 33979]]

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). The result provides one 
single density estimate value for each species across broad geographic 
areas. This is the general approach applied in estimating cetacean 
abundance in NMFS' Stock Assessment Reports (SARs). Although the single 
value provides a good average estimate of abundance (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 developed by NMFS' 
Southwest Fisheries Science Center has been used to estimate cetacean 
densities (Barlow et al., 2009; Becker et al., 2010, 2012a, b, c, 2014, 
2016; Ferguson et al., 2006a; Forney et al., 2012, 2015; Redfern et 
al., 2006). 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 estimate the impacts of 
Navy activities on marine species. However, in many places, ship 
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 marine species density for large oceanic regions, 
the Navy reviews, critically assesses, and prioritizes 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 Navy Marine Species Density Database (NMSDD), which 
includes seasonal density values for every marine mammal species and 
stock present within the NWTT Study Area. This database is described in 
the technical report titled ``U.S. Navy Marine Species Density Database 
Phase III for the Northwest Training and Testing Study Area'' (U.S. 
Department of the Navy, 2019), hereafter referred to as the Density 
Technical Report. NMFS vetted all cetacean densities by the Navy prior 
to use in the Navy's acoustic analysis for the current NWTT rulemaking 
process.
    A variety of density data and density models are needed in order to 
develop a density database that encompasses the entirety of the NWTT 
Study Area. Because this data is collected using different methods with 
varying amounts of accuracy and uncertainty, the Navy has developed a 
hierarchy to ensure the most accurate data is used when available. The 
Density Technical Report describes these models in detail and provides 
detailed explanations of the models applied to each species density 
estimate. The below list describes models in order of preference.
    1. Spatial density models are preferred and used when available 
because they provide an estimate with the least amount of uncertainty 
by deriving estimates for divided segments of the sampling area. These 
models (see Becker et al., 2016; Forney et al., 2015) predict spatial 
variability of animal presence as a function of habitat variables 
(e.g., sea surface temperature, seafloor depth, etc.). This model is 
developed for areas, species, and, when available, specific timeframes 
(months or seasons) with sufficient survey data; therefore, this model 
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 (stratified) into sub-
regions, and a density is predicted for each sub-region (see Barlow, 
2016; Becker et al., 2016; Bradford et al., 2017; Campbell et al., 
2014; Jefferson et al., 2014). 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 
from land and aerial surveys designed to cover a specific geographic 
area (see Carretta et al., 2015). 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. 
Although relative environmental suitability (RES) models provide 
estimates for areas of the oceans that have not been surveyed using 
information on species occurrence and inferred habitat associations and 
have been used in past density databases, these models were not used in 
the current quantitative analysis.
    The Navy describes some of the challenges of interpreting the 
results of the quantitative analysis summarized above and described in 
the Density Technical Report: ``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

[[Page 33980]]

population is perfect, and with regards to marine mammal 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 (U.S. Department of 
the Navy, 2017a).''
    The Navy's estimate of abundance (based on density estimates used 
in the NWTT Study Area) utilizes NMFS' SARs, except for species with 
high site fidelity/smaller home ranges within the NWTT Study Area, 
relative to their geographic distribution (e.g., harbor seals). For 
harbor seals in the inland waters, more up-to-date, site specific 
population estimates were available. 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 NWTT 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.

Take Request

    The 2019 NWTT DSEIS/OEIS considered all training and testing 
activities proposed to occur in the NWTT Study Area that have the 
potential to result in the MMPA defined take of marine mammals. The 
Navy determined that the three stressors below could result in the 
incidental taking of marine mammals. NMFS has reviewed the Navy's 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 Navy's planned activities.
     Acoustics (sonar and other transducers);
     Explosives (explosive shock wave and sound, assumed to 
encompass the risk due to fragmentation); and
     Vessel strike
    Acoustic and explosive sources have the potential to result in 
incidental takes of marine mammals by harassment and injury. Vessel 
strikes have the potential to result in incidental take from injury, 
serious injury, and/or mortality.
    The quantitative analysis process used for the 2019 NWTT DSEIS/OEIS 
and the Navy's take request in the rulemaking/LOA application to 
estimate potential exposures to marine mammals resulting from acoustic 
and explosive stressors is detailed in the technical report titled 
Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods 
and Analytical Approach for Phase III Training and Testing (U.S. 
Department of the Navy, 2018). The Navy Acoustic Effects Model 
estimates acoustic and explosive effects without taking mitigation into 
account; therefore, the model overestimates predicted impacts on marine 
mammals within mitigation zones. To account for mitigation for marine 
species in the take estimates, the Navy conducts a quantitative 
assessment of mitigation. The Navy conservatively quantifies the manner 
in which procedural mitigation is expected to reduce the risk for 
model-estimated PTS for exposures to sonars and for model-estimated 
mortality for exposures to explosives, based on species sightability, 
observation area, visibility, and the ability to exercise positive 
control over the sound source. Where the analysis indicates mitigation 
would effectively reduce risk, the model-estimated PTS are considered 
reduced to TTS and the model-estimated mortalities are considered 
reduced to injury. For a complete explanation of the process for 
assessing the effects of mitigation, see the Navy's rulemaking/LOA 
application and the technical report titled Quantifying Acoustic 
Impacts on Marine Mammals and Sea Turtles: Methods and Analytical 
Approach for Phase III Training and Testing (U.S. Department of the 
Navy, 2018). The extent to which the mitigation areas reduce impacts on 
the affected species is addressed separately in the Preliminary 
Analysis and Negligible Impact Determination section.
    The Navy assessed the effectiveness of its procedural mitigation 
measures on a per-scenario basis for four factors: (1) Species 
sightability, (2) a Lookout's ability to observe the range to PTS (for 
sonar and other transducers) and range to mortality (for explosives), 
(3) the portion of time when mitigation could potentially be conducted 
during periods of reduced daytime visibility (to include inclement 
weather and high sea-state) and the portion of time when mitigation 
could potentially be conducted at night, and (4) the ability for sound 
sources to be positively controlled (e.g., powered down).
    During training and testing 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, as a conservative approach to assigning 
mitigation effectiveness factors, the Navy elected to only account for 
the minimum number of required Lookouts used for each activity; 
therefore, the mitigation effectiveness factors may underestimate the 
likelihood that some marine mammals may be detected during activities 
that are supported by additional personnel who may also be observing 
the mitigation zone.
    The Navy used the equations in the below sections to calculate the 
reduction in model-estimated mortality impacts due to implementing 
procedural mitigation.
    Equation 1:

Mitigation Effectiveness = Species Sightability x Visibility x 
Observation Area x Positive Control

    Species Sightability is the ability to detect marine mammals and is 
dependent on the animal's presence at the surface and the 
characteristics of the animal that influence its sightability. The Navy 
considered applicable data from the best available science to 
numerically approximate the sightability of marine mammals and 
determined the standard ``detection probability'' referred to as g(0) 
is most appropriate. Also, Visibility = 1-sum of individual visibility 
reduction factors; Observation Area = portion of impact range that can 
be continuously observed during an event; and Positive Control = 
positive control factor of all sound sources involving mitigation. For 
further details on these mitigation effectiveness factors please refer 
to the technical report titled Quantifying Acoustic Impacts on Marine 
Mammals and Sea Turtles: Methods and Analytical Approach for Phase III 
Training and

[[Page 33981]]

Testing (U.S. Department of the Navy, 2018).
    To quantify the number of marine mammals predicted to be sighted by 
Lookouts in the injury zone during implementation of procedural 
mitigation for sonar and other transducers, the species sightability is 
multiplied by the mitigation effectiveness scores and number of model-
estimated PTS impacts, as shown in the equation below:
    Equation 2:

Number of Animals Sighted by Lookouts = Mitigation Effectiveness x 
Model-Estimated Impacts

    The marine mammals sighted by Lookouts in the injury zone during 
implementation of mitigation, as calculated by the equation above, 
would avoid being exposed to these higher level impacts. To quantify 
the number of marine mammals predicted to be sighted by Lookouts in the 
mortality zone during implementation of procedural mitigation during 
events using explosives, the species sightability is multiplied by the 
mitigation effectiveness scores and number of model-estimated mortality 
impacts, as shown in equation 1 above. The marine mammals predicted to 
be sighted in the mortality zone by Lookouts during implementation of 
procedural mitigation, as calculated by the above equation 2, are 
predicted to avoid exposure in these ranges. The Navy corrects the 
category of predicted impact for the number of animals sighted within 
the mitigation zone, but does not modify the total number of animals 
predicted to experience impacts from the scenario. For example, the 
number of animals sighted (i.e., number of animals that will avoid 
mortality) is first subtracted from the model-predicted mortality 
impacts, and then added to the model-predicted injurious impacts.
    The NAEMO (animal movement) model overestimates the number of 
marine mammals that would be exposed to sound sources that could cause 
PTS because the model does not consider horizontal movement of animats, 
including avoidance of high intensity sound exposures. Therefore, the 
potential for animal avoidance is considered separately. At close 
ranges and high sound levels, avoidance of the area immediately around 
the sound source is one of the assumed behavioral responses for marine 
mammals. Animal avoidance refers to the movement out of the immediate 
injury zone for subsequent exposures, not wide-scale area avoidance. 
Various researchers have demonstrated that cetaceans can perceive the 
location and movement of a sound source (e.g., vessel, seismic source, 
etc.) relative to their own location and react with responsive movement 
away from the source, often at distances of 1 km or more (Au & 
Perryman,1982; Jansen et al., 2010; Richardson et al., 1995; Tyack et 
al., 2011; Watkins, 1986; W[uuml]rsig et al., 1998) A marine mammal's 
ability to avoid a sound source and reduce its cumulative sound energy 
exposure would reduce risk of both PTS and TTS. However, the 
quantitative analysis conservatively only considers the potential to 
reduce some instances of PTS by accounting for marine mammals swimming 
away to avoid repeated high-level sound exposures. All reductions in 
PTS impacts from likely avoidance behaviors are instead considered TTS 
impacts.
    NMFS coordinated with the Navy in the development of this 
quantitative method to address the effects of procedural mitigation on 
acoustic and explosive exposures and takes, and NMFS independently 
reviewed and concurs with the Navy that it is appropriate to 
incorporate the quantitative assessment of mitigation into the take 
estimates based on the best available science. For additional 
information on the quantitative analysis process and mitigation 
measures, refer to the technical report titled Quantifying Acoustic 
Impacts on Marine Mammals and Sea Turtles: Methods and Analytical 
Approach for Phase III Training and Testing (U.S. Department of the 
Navy, 2018) and Chapter 6 (Take Estimates for Marine Mammals) and 
Chapter 11 (Mitigation Measures) of the Navy's rulemaking/LOA 
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 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 Navy's 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, the NAEMO model is the result of a NMFS-led Center for 
Independent Experts (CIE) review of the components used in earlier 
models. The acoustic propagation component of the NAEMO model (CASS/
GRAB) is accredited by the Oceanographic and Atmospheric Master Library 
(OAML), and many of the environmental variables used in the NAEMO model 
come from approved OAML databases and are based on in-situ data 
collection. The animal density components of the NAEMO model 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 the Duke University habitat-based density models, 
have been published in peer reviewed literature. Others like the 
Atlantic Marine Assessment Program for Protected Species, which was 
conducted by NMFS Science Centers, have undergone quality assurance and 
quality control (QA/QC) processes. Finally, the NAEMO model simulation 
components underwent 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 Navy's methods, including the method for 
incorporating mitigation and avoidance, are the most appropriate 
methods for predicting PTS, tissue damage, TTS, and behavioral 
disruption. But even with the consideration of mitigation and 
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 PTS, tissue damage, 
TTS, or behavioral disruption.

[[Page 33982]]

Summary of Requested Take From Training and Testing Activities
    Based on the methods discussed in the previous sections and the 
Navy's model and quantitative assessment of mitigation, the Navy 
provided its take estimate and request for authorization of takes 
incidental to the use of acoustic and explosive sources for training 
and testing activities both annually (based on the maximum number of 
activities that could occur per 12-month period) and over the seven-
year period covered by the Navy's rulemaking/LOA application. The 
following species/stocks present in the NWTT Study Area were modeled by 
the Navy and estimated to have 0 takes of any type from any activity 
source: Eastern North Pacific Northern Resident stock of killer whales, 
Western North Pacific stock of gray whales, and California stock of 
harbor seals. NMFS has reviewed the Navy's 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.
Estimated Harassment Take From Training and Testing Activities
    For training and testing activities, Tables 32 and 33 summarize the 
Navy's take estimate and request and the annual and maximum amount and 
type of Level A harassment and Level B harassment for the seven-year 
period that NMFS concurs is reasonably expected to occur by species and 
stock. Note that take by Level B harassment includes both behavioral 
disruption and TTS. Tables 6-14-41 (sonar and other transducers) and 6-
56-71 (explosives) in Section 6 of the Navy's rulemaking/LOA 
application provide the comparative amounts of TTS and behavioral 
disruption for each species and stock annually, noting that if a 
modeled marine mammal was ``taken'' through exposure to both TTS and 
behavioral disruption in the model, it was recorded as a TTS.

 Table 32--Annual and Seven-Year Total Species-Specific Take Estimates Proposed for Authorization From Acoustic
              and Explosive Sound Source Effects for all Training Activities in the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                              Annual                       7-Year total
            Species                   Stock      ---------------------------------------------------------------
                                                      Level B         Level A         Level B         Level A
----------------------------------------------------------------------------------------------------------------
                                                  Order Cetacea
----------------------------------------------------------------------------------------------------------------
                                       Suborder Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
 (rorquals):
    Blue whale *..............  Eastern North                  2               0              11               0
                                 Pacific.
    Fin whale *...............  Northeast                      0               0               0               0
                                 Pacific.
                                California/                   54               0             377               0
                                 Oregon/
                                 Washington.
    Sei whale *...............  Eastern North                 30               0             206               0
                                 Pacific.
    Minke whale...............  Alaska..........               0               0               0               0
                                California/                  110               0             767               0
                                 Oregon/
                                 Washington.
    Humpback whale *..........  Central North                  5               0              31               0
                                 Pacific.
                                California/                    4               0              32               0
                                 Oregon/
                                 Washington.
Family Eschrichtiidae (gray
 whale):
    Gray whale................  Eastern North                  2               0              10               0
                                 Pacific.
----------------------------------------------------------------------------------------------------------------
                                      Suborder Odontoceti (toothed whales)
----------------------------------------------------------------------------------------------------------------
Family Delphinidae (dolphins):
    Bottlenose dolphin........  California/                    5               0              33               0
                                 Oregon/
                                 Washington
                                 Offshore.
    Killer whale..............  Alaska Resident.               0               0               0               0
                                Eastern North                 68               0             478               0
                                 Pacific
                                 Offshore.
                                West Coast                    78               0             538               0
                                 Transient.
                                Southern                       3               0              15               0
                                 Resident
                                 [cross5].
    Northern right whale        California/                7,941               0          55,493               0
     dolphin.                    Oregon/
                                 Washington.
    Pacific white-sided         North Pacific...               0               0               0               0
     dolphin.
                                California/                5,284               0          36,788               0
                                 Oregon/
                                 Washington.
    Risso's dolphin...........  California/                2,286               0          15,972               0
                                 Oregon/
                                 Washington.
    Short-beaked common         California/                1,165               0           8,124               0
     dolphin.                    Oregon/
                                 Washington.
    Short-finned pilot whale..  California/                   57               0             398               0
                                 Oregon/
                                 Washington.
    Striped dolphin...........  California/                  439               0           3,059               0
                                 Oregon/
                                 Washington.
Family Kogiidae (Kogia
 species):
    Kogia species Pygmy.......  California/                  381               0           2,664               0
                                 Oregon/
                                 Washington.
Family Phocoenidae
 (porpoises):
    Dall's porpoise...........  Alaska..........               0               0               0               0
                                California/               13,299               8          92,793              48
                                 Oregon/
                                 Washington.
    Harbor porpoise...........  Southeast Alaska               0               0               0               0
                                Northern Oregon/             299               0           2,092               0
                                 Washington
                                 Coast.
                                Northern                      21               0             145               0
                                 California/
                                 Southern Oregon.
                                Washington                12,315              43          79,934             291
                                 Inland Waters.
Family Physeteridae (sperm
 whale):
    Sperm whale *.............  California/                  512               0           3,574               0
                                 Oregon/
                                 Washington.
Family Ziphiidae (beaked
 whales):
    Baird's beaked whale......  California/                  556               0           3,875               0
                                 Oregon/
                                 Washington.
    Cuvier's beaked whale.....  California/                1,462               0          10,209               0
                                 Oregon/
                                 Washington.

[[Page 33983]]

 
    Mesoplodon species........  California/                  652               0           4,549               0
                                 Oregon/
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                               Suborder Pinnipedia
----------------------------------------------------------------------------------------------------------------
Family Otariidae (sea lions
 and fur seals):
    California sea lion.......  U.S. Stock......           3,624               0          25,243               0
    Steller sea lion..........  Eastern U.S.....             108               0             743               0
    Guadalupe fur seal *......  Mexico..........             608               0           4,247               0
    Northern fur seal.........  Eastern Pacific.           2,134               0          14,911               0
                                California......              43               0             300               0
Family Phocidae (true seals):
    Harbor seal...............  Southeast                      0               0               0               0
                                 Alaska--Clarenc
                                 e Strait.
                                Oregon/                        0               0               0               0
                                 Washington
                                 Coastal.
                                Washington                   669               5           3,938              35
                                 Northern Inland
                                 Waters.
                                Hood Canal......           2,686               1          18,662               5
                                Southern Puget             1,090               1           6,657               6
                                 Sound.
    Northern elephant seal....  California......           1,909               1          13,324               1
----------------------------------------------------------------------------------------------------------------
* ESA-listed species (all stocks) within the NWTT Study Area.
[cross5] Only designated stocks are ESA-listed.


 Table 33--Annual and Seven-Year Total Species-Specific Take Estimates Proposed for Authorization From Acoustic
              and Explosive Sound Source Effects for all Training Activities in the NWTT Study Area
----------------------------------------------------------------------------------------------------------------
                                                              Annual                       7-Year total
            Species                   Stock      ---------------------------------------------------------------
                                                      Level B         Level A         Level B         Level A
----------------------------------------------------------------------------------------------------------------
                                                  Order Cetacea
----------------------------------------------------------------------------------------------------------------
                                       Suborder Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
 (rorquals):
    Blue whale *..............  Eastern North                  8               0              38               0
                                 Pacific.
    Fin whale *...............  Northeast                      2               0              10               0
                                 Pacific.
                                California/                   81               0             392               0
                                 Oregon/
                                 Washington.
    Sei whale *...............  Eastern North                 53               0             258               0
                                 Pacific.
    Minke whale...............  Alaska..........               2               0               9               0
                                California/                  192               0             916               0
                                 Oregon/
                                 Washington.
    Humpback whale *..........  Central North                110               0             578               0
                                 Pacific.
                                California/                   89               0             460               0
                                 Oregon/
                                 Washington.
Family Eschrichtiidae (gray
 whale):
    Gray whale................  Eastern North                 41               0             189               0
                                 Pacific.
----------------------------------------------------------------------------------------------------------------
                                      Suborder Odontoceti (toothed whales)
----------------------------------------------------------------------------------------------------------------
Family Delphinidae (dolphins):
    Bottlenose dolphin........  California/                    3               0              14               0
                                 Oregon/
                                 Washington
                                 Offshore.
    Killer whale..............  Alaska Resident.              34               0             202               0
                                Eastern North                 89               0             412               0
                                 Pacific
                                 Offshore.
                                West Coast                   154               0             831               0
                                 Transient.
                                Southern                      48               0             228               0
                                 Resident
                                 [cross5].
    Northern right whale        California/               13,759               1          66,457               7
     dolphin.                    Oregon/
                                 Washington.
    Pacific white-sided         North Pacific...             101               0             603               0
     dolphin.
                                California/               15,681               1          76,980               8
                                 Oregon/
                                 Washington.
    Risso's dolphin...........  California/                4,069               0          19,637               0
                                 Oregon/
                                 Washington.
    Short-beaked common         California/                  984               0           3,442               0
     dolphin.                    Oregon/
                                 Washington.
    Short-finned pilot whale..  California/                   31               0             126               0
                                 Oregon/
                                 Washington.
    Striped dolphin...........  California/                  344               0           1,294               0
                                 Oregon/
                                 Washington.
Family Kogiidae (Kogia
 species):
    Kogia species.............  California/                  501               1           2,376               9
                                 Oregon/
                                 Washington.
Family Phocoenidae
 (porpoises):
    Dall's porpoise...........  Alaska..........             638               0           3,711               0
                                California/               20,398              90          98,470             523
                                 Oregon/
                                 Washington.
    Harbor porpoise...........  Southeast Alaska             130               0             794               0
                                Northern Oregon/          52,113             103         265,493             525
                                 Washington
                                 Coast.

[[Page 33984]]

 
                                Northern                   2,018              86          12,131             432
                                 California/
                                 Southern Oregon.
                                Washington                17,228             137         115,770             930
                                 Inland Waters.
Family Physeteridae (sperm
 whale):
    Sperm whale *.............  California/                  327               0           1,443               0
                                 Oregon/
                                 Washington.
Family Ziphiidae (beaked
 whales):
    Baird's beaked whale......  California/                  420               0           1,738               0
                                 Oregon/
                                 Washington.
    Cuvier's beaked whale.....  California/                1,077               0           4,979               0
                                 Oregon/
                                 Washington.
    Mesoplodon species........  California/                  470               0           2,172               0
                                 Oregon/
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                               Suborder Pinnipedia
----------------------------------------------------------------------------------------------------------------
Family Otariidae (sea lions
 and fur seals):
    California sea lion.......  U.S. Stock......          20,474               1          93,906               5
    Steller sea lion..........  Eastern U.S.....           2,130               0          10,745               0
    Guadalupe fur seal *......  Mexico..........             887               0           4,022               0
    Northern fur seal.........  Eastern Pacific.           9,458               0          45,813               0
                                California......             189               0             920               0
Family Phocidae (true seals):
    Harbor seal...............  Southeast                  2,352               0          13,384               0
                                 Alaska--Clarenc
                                 e Strait.
                                Oregon/                    1,180               2           6,222              11
                                 Washington
                                 Coastal.
                                Washington                   578               0           3,227               0
                                 Northern Inland
                                 Waters.
                                Hood Canal......          58,784               0         396,883               0
                                Southern Puget             5,748               3          39,511              24
                                 Sound.
    Northern elephant seal....  California......           2,935               3          14,120              18
----------------------------------------------------------------------------------------------------------------
* ESA-listed species (all stocks) within the NWTT Study Area.
[cross5] Only designated stocks are ESA-listed.

Estimated Take From Vessel Strikes 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 occasional fatalities to cetaceans (Berman-Kowalewski et al., 2010; 
Calambokidis, 2012; Douglas et al., 2008; Laggner 2009; Lammers et al., 
2003). Records of collisions date back to the early 17th century, and 
the worldwide number of collisions 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; Lemon et al., 2006; 
Lusseau, 2003; Lusseau, 2006; Magalhaes et al., 2002; Nowacek et al., 
2001; Richter et al., 2003; Scheidat et al., 2004; Simmonds, 2005; 
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). Water disturbance may also be a factor. 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 Navy is conducting training or testing 
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 collisions 
(Nowacek et al., 2004). These species are primarily large, slow moving 
whales.
    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 ship to detect a 
marine mammal and avoid a collision depends on a variety of factors, 
including environmental conditions, ship 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. For example, Vanderlaan and Taggart 
(2007) found that between vessel speeds of 8.6 and 15 knots, the 
probability that a vessel strike is lethal increases from 0.21 to 0.79. 
Large whales also do not have to be at the water's surface to be 
struck. Silber et al. (2010) found 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.

[[Page 33985]]

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:
     Many military ships have their bridges positioned closer 
to the bow, offering better visibility ahead of the ship (compared to a 
commercial merchant vessel);
     There are often aircraft associated with the training or 
testing activity (which can serve as Lookouts), which can more readily 
detect cetaceans in the vicinity of a vessel or ahead of a vessel's 
present course before crew on the vessel would be able to detect them;
     Military ships are generally more maneuverable than 
commercial merchant vessels, and if cetaceans are spotted in the path 
of the ship, could be capable of changing course more quickly;
     The crew size on military vessels is generally larger than 
merchant ships, allowing for stationing more trained Lookouts on the 
bridge. At all times when Navy 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. Additional 
Lookouts, beyond those already stationed on the bridge and on 
navigation teams, are positioned as Lookouts during some training 
events; and
     When submerged, submarines are generally slow moving (to 
avoid detection) and therefore marine mammals at depth with a submarine 
are likely able to avoid collision with the submarine. When a submarine 
is transiting on the surface, there are Lookouts serving the same 
function as they do on surface ships.
    Vessel strike to marine mammals is not associated with any specific 
training or testing activity but is rather an extremely limited and 
sporadic, but possible, accidental result of Navy vessel movement 
within the NWTT Study Area or while in transit.
    Data from the ports of Vancouver, British Columbia; Seattle, 
Washington; and Tacoma, Washington indicate there were more than 7,000 
commercial vessel transits in 2017 associated with visits to just those 
ports (The Northwest Seaport Alliance, 2018; Vancouver Fraser Port 
Authority). This number of vessel transits does not account for other 
vessel traffic in the Strait of Juan de Fuca or Puget Sound including 
commercial ferries, tourist vessels, or recreational vessels. 
Additional commercial traffic in the NWTT Study Area also includes 
vessels transiting offshore along the Pacific coast, bypassing ports in 
Canada and Washington; traffic associated with ports to the south along 
the coast of Washington and in Oregon; and vessel traffic in Southeast 
Alaska (Nuka Research & Planning Group, 2012). Navy vessel traffic 
accounts for only a small portion of vessel activities in the NWTT 
Study Area. The Navy has, in total, the following homeported 
operational vessels: 2 Aircraft carriers, 6 destroyers, 14 submarines, 
and 22 smaller security vessels with a combined annual total of 241 
Navy vessel transits (see Appendix A (Navy Activities Descriptions) of 
the 2019 DSEIS/OEIS for descriptions of the number of vessels used 
during the various types of Navy's proposed activities). Activities 
involving military vessel movement would be widely dispersed throughout 
the NWTT Study Area.
    Navy vessel strike records have been kept since 1995, and since 
1995 there have been two recorded strikes of whales by Navy vessels (or 
vessels being operated on behalf of the Navy) in the NWTT Study Area. 
Neither strike was associated with training or testing activities. The 
first strike occurred in 2012 by a Navy destroyer off the southern 
coast of Oregon while in transit to San Diego. The whale was suspected 
to be a minke whale due to the appearance and size (25 ft, dark with 
white belly), however the Navy could not rule out the possibility that 
it was a juvenile fin whale. The whale was observed swimming after the 
strike and no blood or injury was sighted. The second strike occurred 
in 2016 by a U.S. Coast Guard cutter operating on behalf of the Navy as 
part of a Maritime Security Operation escort vessel in the Strait of 
Juan de Fuca. The whale was positively identified as a humpback whale. 
It was observed for 10 minutes post-collision and appeared normal at 
the surface. There was no blood observed in the water and the whale 
subsequently swam away.
    In order to account for the potential risk from vessel movement 
within the NWTT Study Area within the seven-year period in particular, 
the Navy requested incidental takes based on probabilities derived from 
a Poisson distribution using ship strike data between 2009-2018 in the 
NWTT Study Area (the time period from when current mitigation measures 
to reduce the likelihood of vessel strikes were instituted until the 
Navy conducted the analysis for the Navy's application), as well as 
historical at-sea days in the NWTT Study Area from 2009-2018 and 
estimated potential at-sea days for the period from 2020 to 2027 
covered by the requested regulations. This distribution predicted the 
probabilities of a specific number of strikes (n = 0, 1, 2, etc.) over 
the period from 2020 to 2027. The analysis for the period of 2020 to 
2027 is described in detail in Chapter 6.6 (Vessel Strike Analysis) of 
the Navy's rulemaking/LOA application.
    For the same reasons listed above, describing why a Navy vessel 
strike is comparatively unlikely, it is highly unlikely that a Navy 
vessel would strike a whale, dolphin, porpoise, or pinniped without 
detecting it and, accordingly, NMFS is confident that the Navy's 
reported strikes are accurate and appropriate for use in the analysis. 
Specifically, Navy ships have multiple Lookouts, including on the 
forward part of the ship that can visually detect a hit animal, in the 
unlikely event ship personnel do not feel the strike. Unlike the 
situation for non-Navy ships engaged in commercial activities, NMFS and 
the Navy have no evidence that the Navy has struck a whale and not 
detected it. Navy's strict internal procedures and mitigation 
requirements include reporting of any vessel strikes of marine mammals, 
and the Navy's 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 actually get reported.
    The Navy used those two whale strikes in their calculations to 
determine the number of strikes likely to result from their activities 
and evaluated data beginning in 2009. The Navy's Marine Species 
Awareness Training was first used in 2006 and was fully integrated 
across the Navy in 2009, which is why the Navy uses 2009 as the date to 
begin the analysis. The adoption of additional mitigation measures to 
address ship strike also began in 2009, and will remain in place along 
with additional mitigation measures during the seven years of this 
rule. The probability analysis concluded that there was a 26 percent 
chance that zero whales would be struck by Navy vessels over the seven-
year period, and a 35, 24, 11, and 4 percent chance that one, two, 
three, or four whales, respectively, would be struck over the seven-
year period (with a 74 percent chance total that at least one whale 
would be struck over the seven-year period). Therefore, the Navy 
estimates, and NMFS agrees, that there is some probability that the 
Navy could strike, and take by serious injury or

[[Page 33986]]

mortality, up to three large whales incidental to training and testing 
activities within the NWTT Study Area over the course of the seven 
years.
    Small whales, delphinids, porpoises, and pinnipeds are not expected 
to be struck by Navy vessels. In addition to the reasons listed above 
that make it unlikely that the Navy will hit a large whale (more 
maneuverable ships, larger crew, etc.), the following are the 
additional reasons that vessel strike of dolphins, small whales, 
porpoises, and pinnipeds is considered very unlikely. Dating back more 
than 20 years and for as long as it has kept records, the Navy has no 
records of individuals of these groups being struck by a vessel as a 
result of Navy activities and, further, their smaller size and 
maneuverability make a strike unlikely. Also, NMFS has never received 
any reports from other authorized activities indicating that these 
species have been struck by vessels. Worldwide ship strike records show 
little evidence of strikes of these groups from the shipping sector and 
larger vessels and the majority of the Navy's 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. Based on this information, 
NMFS concurs with the Navy's assessment and recognizes the potential 
for incidental take by vessel strike of large whales only (i.e., no 
dolphins, small whales, porpoises, or pinnipeds) over the course of the 
seven-year regulations from training and testing activities.
    Taking into account the available information regarding how many of 
any given stock could be struck and therefore should be authorized for 
take, NMFS considered three factors in addition to those considered in 
the Navy's request: (1) The relative likelihood of hitting one stock 
versus another based on available strike data from all vessel types as 
denoted in the SARs, (2) whether the Navy has ever definitively struck 
an individual from a particular species or stock in the NWTT Study 
Area, and if so, how many times, and (3) whether there are records that 
an individual from a particular species or stock has been struck by any 
vessel in the NWTT Study Area, and if so, how many times (based on ship 
strike records provided by the NMFS West Coast Region in February 
2020). To address number (1) above, NMFS compiled information from 
NMFS' SARs on detected annual rates of large whale serious injury or 
mortality (M/SI) from vessel collisions (Table 34). The annual rates of 
large whale serious injury or mortality from vessel collisions from the 
SARs help inform the relative susceptibility of large whale species to 
vessel strike in NWTT Study Area as recorded systematically over the 
last five years (the period used for the SARs). However, we note that 
the SARs present strike data from the stock's entire range, which is 
much larger than the NWTT Study Area, and available ship strike records 
show that the majority of strikes that occur off the United States West 
Coast occur in southern California. We summed the annual rates of 
serious injury or mortality from vessel collisions as reported in the 
SARs, then divided each species' annual rate by this sum to get the 
proportion of strikes for each species/stock. To inform the likelihood 
of striking a particular species of large whale, we multiplied the 
proportion of striking each species by the probability of striking at 
least one whale (i.e., 74 percent, as described by the Navy's 
probability analysis above). We note that these probabilities vary from 
year to year as the average annual mortality for a given five-year 
window in the SAR changes; however, over the years and through changing 
SARs, stocks tend to consistently maintain a relatively higher or 
relatively lower likelihood of being struck (and we include the annual 
averages from 2017 SARs in Table 34 to illustrate).
    The probabilities calculated as described above are then considered 
in combination with the information indicating the species that the 
Navy has definitively hit in the NWTT Study Area since 1995 (since they 
started tracking consistently) and the species that are known to have 
been struck by any vessel (through regional stranding data) in the NWTT 
Study Area. We also note that Rockwood et al. (2017) modeled the likely 
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 will hit those stocks.
    For each indicated stock, Table 34 includes the percent likelihood 
of hitting an individual whale once based on SAR data, total strikes 
from Navy vessels (from 1995), total strikes from any vessel (from 2000 
from regional stranding data), and modeled vessel strikes from Rockwood 
et al. (2017). The last column indicates the annual serious injury or 
mortality proposed for authorization.

                                  Table 34--Summary of Factors Considered in Determining the Number of Individuals in Each Stock Potentially Struck by a Vessel
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                      Percent
                                                                                          Annual rate  Annual rate   likelihood  Total known
                                                                                             of M/SI      of M/SI    of hitting   strikes in  Total known    Rockwood       MMPA
                                                                                              from         from      individual     OR, WA,       navy        et al.      proposed      Annual
              ESA status                        Species                   Stock              vessel       vessel        from     northern CA  strikes  in     (2017)     authorized    proposed
                                                                                           collision    collision     species/    (from 2000  NWTT  study    modeled       takes      authorized
                                                                                           (observed    (observed    stock once  to present)      area        vessel    (from the 3      take
                                                                                           from 2017    from 2019    (from 2019      \1\                   strikes \5\     total)
                                                                                             SARs)     Draft SARs)  Draft SARs)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Listed...............................  Blue whale..............  Eastern North Pacific..            0          0.4          3.7                                     18            0            0
                                       Fin whale...............  Northeast Pacific......          0.2          0.4          3.7       \2\ 10                                      2         0.29
                                                                 CA/OR/WA...............          1.8          1.6         14.8       \2\ 10                        43            2         0.29
                                       Sei whale...............  Eastern North Pacific..            0          0.2         1.85                                                   0            0
                                       Humpback whale..........  CA/OR/WA (Mexico and             1.1          2.1       19.425        \3\ 4        \4\ 1           22            2         0.29
                                                                  Central America DPS).
                                       Sperm whale.............  CA/OR/WA...............          0.2            0            0            3                                      1         0.14
Not Listed...........................  Minke whale.............  Alaska.................            0            0            0                                                   0            0
                                                                 CA/OR/WA...............            0            0            0            1            1                         1         0.14
                                       Gray whale..............  Eastern North Pacific..            2          0.8          7.4            9                                      1         0.14
                                       Humpback whale..........  Central North Pacific            2.6          2.5       23.125        \3\ 4        \4\ 1                         2         0.29
                                                                  (Hawaii DPS).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Only one ship strike was reported in California in the NWTT Study Area (which is limited to Humbolt and Del Norte Counties). This strike occurred in 2004 in Humbolt County and was not
  identified to species.
\2\ A total of 10 fin whale strikes are reported in the regional stranding database, however no information on stock is provided. As these two stocks of fin whales are known to overlap
  spatially and temporally in the NWTT Study Area, the 10 reported strikes could come from either stock or a combination of both stocks.
\3\ A total of 4 humpback whales strikes are reported in the regional stranding database, however no information on stock is provided. As these two stocks of humpback whales are known to
  overlap spatially and temporally in the NWTT Study Area, the 4 reported strikes could come from either stock or a combination of both stocks.
\4\ One humpback whale was reported as struck by a U.S. Coast Guard cutter operating on behalf of the Navy, however it was not possible for the Navy to determine which stock this whale came
  from. As these two stocks of humpback whales are known to overlap spatially and temporally in the NWTT Study Area, this whale could have come from either stock.

[[Page 33987]]

 
\5\ Rockwood et al. modeled likely annual vessel strikes off the West Coast for these three species only.

    Accordingly, stocks that have no record of having been struck by 
any vessel are considered unlikely to be struck by the Navy in the 
seven-year period of the rule. Stocks that have never been struck by 
the Navy, have rarely been struck by other vessels, and have a low 
likelihood of being struck based on the SAR calculation and a low 
relative abundance (Eastern North Pacific stock of blue whales, Eastern 
North Pacific stock of sei whales, and Alaska stock of minke whales) 
are also considered unlikely to be struck by the Navy during the seven-
year rule. This rules out all but seven stocks.
    The two stocks of humpback whales (CA/OR/WA and Central North 
Pacific) and two stocks of fin whales (CA/OR/WA and Northeast Pacific) 
are known to overlap spatially and temporally in the NWTT Study Area, 
and it is not possible to distinguish the difference between 
individuals of these stocks based on visual sightings in the field. The 
Navy has previously struck a humpback whale in the NWTT Study Area and 
it is the second most common species struck by any vessel in the Study 
Area based on stranding data. Based on the SAR data, the two stocks of 
humpback whales also have the highest likelihood of being struck. 
Though the Navy has not definitively struck a fin whale in the NWTT 
Study Area (noting that the Navy could not rule out that the minke 
whale strike could have been a juvenile fin whale), fin whales are the 
most common species struck by any vessel in the Study Area based on 
stranding data. Based on the SAR data, the CA/OR/WA stock has the third 
highest likelihood of being struck. Based on all of these factors, it 
is considered reasonably likely that humpback whales (from either the 
CA/OR/WA or Central North Pacific stocks) could be struck twice and fin 
whales (from either the CA/OR/WA or Northeast Pacific stocks) could be 
struck twice during the seven-year rule.
    Based on the SAR data, the CA/OR/WA stock of sperm whales and CA/
OR/WA stock of minke whales have a very low likelihood of being struck. 
However, 3 sperm whales have been struck by non-Navy vessels in the 
NWTT Study Area (in 2002, 2007, and 2012) and the Navy has previously 
struck a minke whale in the NWTT Study Area. Therefore, we consider it 
reasonable to predict that an individual from each of these stocks 
could be struck by the Navy once during the seven-year rule. Finally, 
based on stranding data, gray whales are the second most commonly 
struck whale in the NWTT Study Area and the SAR data indicates that on 
average, 0.8 whales from this stock are struck throughout the stock's 
range each year. Based on these data, we consider it reasonable to 
predict that an individual from the Eastern North Pacific stock of gray 
whales could be struck by the Navy once during the seven-year rule.
    In conclusion, although it is generally unlikely that any whales 
will be struck in a year, based on the information and analysis above, 
NMFS anticipates that no more than three whales have the potential to 
be taken by serious injury or mortality over the seven-year period of 
the rule. Of those three whales over the seven years, no more than two 
may come from any of the following species/stocks: Fin whale (which may 
come from either the Northeast Pacific or CA/OR/WA stock) and humpback 
whale (which may come from either the Central North Pacific or CA/OR/WA 
stock). Additionally, of those three whales over the seven years no 
more than one may come from any of the following species/stocks: Sperm 
whale (CA/OR/WA stock), minke whale (CA/OR/WA stock), and gray whale 
(Eastern North Pacific stock). Accordingly, NMFS has evaluated under 
the negligible impact standard the M/SI of 0.14 or 0.29 whales annually 
from each of these species or stocks (i.e., 1 or 2 takes, respectively, 
divided by seven years to get the annual number), along with the 
expected incidental takes by harassment. We do not anticipate, nor 
propose to authorize, ship strike takes to blue whales (Eastern North 
Pacific stock), minke whales (Alaska stock), or sei whales (Eastern 
North Pacific stock).

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.
    In Conservation Council for Hawaii v. National Marine Fisheries 
Service, 97 F. Supp. 3d 1210, 1229 (D. Haw. 2015), the Court stated 
that NMFS ``appear[s] to think [it] satisf[ies] the statutory `least 
practicable adverse impact' requirement with a `negligible impact' 
finding.'' More recently, expressing similar concerns in a challenge to 
a U.S. Navy Surveillance Towed Array Sensor System Low Frequency Active 
Sonar (SURTASS LFA) incidental take rule (77 FR 50290), the Ninth 
Circuit Court of Appeals in Natural Resources Defense Council (NRDC) v. 
Pritzker, 828 F.3d 1125, 1134 (9th Cir. 2016), stated, ``[c]ompliance 
with the `negligible impact' requirement does not mean there [is] 
compliance with the `least practicable adverse impact' standard.'' As 
the Ninth Circuit noted in its opinion, however, the Court was 
interpreting the statute without the benefit of NMFS' formal 
interpretation. We state here explicitly that NMFS is in full agreement 
that the ``negligible impact'' and ``least practicable adverse impact'' 
requirements are distinct, even though both statutory standards refer 
to species and stocks. With that in mind, we provide further 
explanation of our interpretation of least practicable adverse impact, 
and explain what distinguishes it from the negligible impact standard. 
This discussion is consistent with previous rules we have published, 
such as the Navy's Hawaii-Southern California Training and Testing 
(HSTT) rule (83 FR 66846; December 27, 2018), Atlantic Fleet Training 
and Testing (AFTT) rule (84 FR 70712; December 23, 2019), and Mariana 
Islands Training and Testing (MITT) proposed rule (85 FR 5782; January 
31, 2020).
    Before NMFS can issue incidental take regulations under section 
101(a)(5)(A) of the MMPA, it must make a finding that the total taking 
will have a ``negligible impact'' on the affected ``species or stocks'' 
of marine mammals. NMFS' and U.S. Fish and Wildlife Service's 
implementing regulations for section 101(a)(5) both define ``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 and 50 CFR 18.27(c)). 
Recruitment (i.e., reproduction) and survival rates are used to 
determine

[[Page 33988]]

population growth rates \3\ and, therefore are considered in evaluating 
population level impacts.
---------------------------------------------------------------------------

    \3\ A growth rate can be positive, negative, or flat.
---------------------------------------------------------------------------

    As stated in the preamble to the proposed rule for the MMPA 
incidental take implementing regulations, not every population-level 
impact violates the negligible impact requirement. The negligible 
impact standard does not require a finding that the anticipated take 
will have ``no effect'' on population numbers or growth rates: The 
statutory standard does not require that the same recovery rate be 
maintained, rather that no significant effect on annual rates of 
recruitment or survival occurs. The key factor is the significance of 
the level of impact on rates of recruitment or survival. (54 FR 40338, 
40341-42; September 29, 1989).
    While some level of impact on population numbers or growth rates of 
a species or stock may occur and still satisfy the negligible impact 
requirement--even without consideration of mitigation--the least 
practicable adverse impact provision separately requires NMFS to 
prescribe means of effecting the least practicable adverse impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, 50 CFR 
216.102(b), which are typically identified as mitigation measures.\4\
---------------------------------------------------------------------------

    \4\ For purposes of this discussion, we omit reference to the 
language in the standard for least practicable adverse impact that 
says we also must mitigate for subsistence impacts because they are 
not at issue in this rule.
---------------------------------------------------------------------------

    The negligible impact and least practicable adverse impact 
standards in the MMPA both call for evaluation at the level of the 
``species or stock.'' The MMPA does not define the term ``species.'' 
However, Merriam-Webster Dictionary defines ``species'' to include 
``related organisms or populations potentially capable of 
interbreeding.'' See www.merriam-webster.com/dictionary/species 
(emphasis added). Section 3(11) of the MMPA defines ``stock'' as a 
group of marine mammals of the same species or smaller taxa in a common 
spatial arrangement that interbreed when mature. The definition of 
``population'' is a group of interbreeding organisms that represents 
the level of organization at which speciation begins. www.merriam-webster.com/dictionary/population. The definition of ``population'' is 
strikingly similar to the MMPA's definition of ``stock,'' with both 
involving groups of individuals that belong to the same species and 
located in a manner that allows for interbreeding. In fact under MMPA 
section 3(11), the term ``stock'' in the MMPA is interchangeable with 
the statutory term ``population stock.'' Both the negligible impact 
standard and the least practicable adverse impact standard call for 
evaluation at the level of the species or stock, and the terms 
``species'' and ``stock'' both relate to populations; therefore, it is 
appropriate to view both the negligible impact standard and the least 
practicable adverse impact standard as having a population-level focus.
    This interpretation is consistent with Congress' statutory findings 
for enacting the MMPA, nearly all of which are most applicable at the 
species or stock (i.e., population) level. See MMPA section 2 (finding 
that it is species and population stocks that are or may be in danger 
of extinction or depletion; that it is species and population stocks 
that should not diminish beyond being significant functioning elements 
of their ecosystems; and that it is species and population stocks that 
should not be permitted to diminish below their optimum sustainable 
population level). Annual rates of recruitment (i.e., reproduction) and 
survival are the key biological metrics used in the evaluation of 
population-level impacts, and accordingly these same metrics are also 
used in the evaluation of population level impacts for the least 
practicable adverse impact standard.
    Recognizing this common focus of the least practicable adverse 
impact and negligible impact provisions on the ``species or stock'' 
does not mean we conflate the two standards; despite some common 
statutory language, we recognize the two provisions are different and 
have different functions. First, a negligible impact finding is 
required before NMFS can issue an incidental take authorization. 
Although it is acceptable to use the mitigation measures to reach a 
negligible impact finding (see 50 CFR 216.104(c)), no amount of 
mitigation can enable NMFS to issue an incidental take authorization 
for an activity that still would not meet the negligible impact 
standard. Moreover, even where NMFS can reach a negligible impact 
finding--which we emphasize does allow for the possibility of some 
``negligible'' population-level impact--the agency must still prescribe 
measures that will affect the least practicable amount of adverse 
impact upon the affected species or stock.
    Section 101(a)(5)(A)(i)(II) requires NMFS to issue, in conjunction 
with its authorization, binding--and enforceable--restrictions (in the 
form of regulations) setting forth how the activity must be conducted, 
thus ensuring the activity has the ``least practicable adverse impact'' 
on the affected species or stocks. In situations where mitigation is 
specifically needed to reach a negligible impact determination, section 
101(a)(5)(A)(i)(II) also provides a mechanism for ensuring compliance 
with the ``negligible impact'' requirement. Finally, the least 
practicable adverse impact standard also requires consideration of 
measures for marine mammal habitat, with particular attention to 
rookeries, mating grounds, and other areas of similar significance, and 
for subsistence impacts, whereas the negligible impact standard is 
concerned solely with conclusions about the impact of an activity on 
annual rates of recruitment and survival.\5\ In NRDC v. Pritzker, the 
Court stated, ``[t]he statute is properly read to mean that even if 
population levels are not threatened significantly, still the agency 
must adopt mitigation measures aimed at protecting marine mammals to 
the greatest extent practicable in light of military readiness needs.'' 
Pritzker at 1134 (emphases added). This statement is consistent with 
our understanding stated above that even when the effects of an action 
satisfy the negligible impact standard (i.e., in the Court's words, 
``population levels are not threatened significantly''), still the 
agency must prescribe mitigation under the least practicable adverse 
impact standard. However, as the statute indicates, the focus of both 
standards is ultimately the impact on the affected ``species or 
stock,'' and not solely focused on or directed at the impact on 
individual marine mammals.
---------------------------------------------------------------------------

    \5\ Outside of the military readiness context, mitigation may 
also be appropriate to ensure compliance with the ``small numbers'' 
language in MMPA sections 101(a)(5)(A) and (D).
---------------------------------------------------------------------------

    We have carefully reviewed and considered the Ninth Circuit's 
opinion in NRDC v. Pritzker in its entirety. While the Court's 
reference to ``marine mammals'' rather than ``marine mammal species or 
stocks'' in the italicized language above might be construed as holding 
that the least practicable adverse impact standard applies at the 
individual ``marine mammal'' level, i.e., that NMFS must require 
mitigation to minimize impacts to each individual marine mammal unless 
impracticable, we believe such an interpretation reflects an incomplete 
appreciation of the Court's holding. In our view, the opinion as a 
whole turned on the Court's determination that NMFS had not given 
separate and independent meaning to the least practicable adverse 
impact standard apart from the negligible impact standard, and further, 
that the Court's use of the term ``marine mammals'' was not addressing 
the

[[Page 33989]]

question of whether the standard applies to individual animals as 
opposed to the species or stock as a whole. We recognize that while 
consideration of mitigation can play a role in a negligible impact 
determination, consideration of mitigation measures extends beyond that 
analysis. In evaluating what mitigation measures are appropriate, NMFS 
considers the potential impacts of the Specified Activities, the 
availability of measures to minimize those potential impacts, and the 
practicability of implementing those measures, as we describe below.

Implementation of Least Practicable Adverse Impact Standard

    Given the NRDC v. Pritzker decision, we discuss here 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 Navy's 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, and their availability 
for subsistence uses (where relevant). This analysis considers such 
things as the nature of the potential adverse impact (such as 
likelihood, scope, and range), the likelihood that the measure will be 
effective if implemented, and the likelihood of successful 
implementation; and
    (2) The practicability of the measures 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 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 (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.\6\ 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.
---------------------------------------------------------------------------

    \6\ We recognize the least practicable adverse impact standard 
requires consideration of measures that will address minimizing 
impacts on the availability of the species or stocks for subsistence 
uses where relevant. Because subsistence uses are not implicated for 
this action, we do not discuss them. However, a similar framework 
would apply for evaluating those measures, taking into account the 
MMPA's directive that we make a finding of no unmitigable adverse 
impact on the availability of the species or stocks for taking for 
subsistence, and the relevant implementing regulations.
---------------------------------------------------------------------------

    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 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

[[Page 33990]]

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 (either 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 potential biological 
removal (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, such as 
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 MMPA section 
101(a)(5)(A)(ii)).

Assessment of Mitigation Measures for NWTT Study Area

    NMFS has fully reviewed the specified activities and the mitigation 
measures included in the Navy's rulemaking/LOA application and the 2019 
NWTT DSEIS/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 Navy in the development of the Navy's 
initially proposed measures, which are informed by years of 
implementation and monitoring. A complete discussion of the Navy's 
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 2019 NWTT DSEIS/OEIS. The process described in 
Chapter 5 (Mitigation) and Appendix K (Geographic Mitigation 
Assessment) of the 2019 NWTT DSEIS/OEIS robustly supported NMFS' 
independent evaluation of whether the mitigation measures would meet 
the least practicable adverse impact standard. The Navy would be 
required to implement the mitigation measures identified in this rule 
for the full seven 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.
    Overall the Navy has agreed to procedural mitigation measures that 
would reduce the probability and/or severity of impacts expected to 
result from acute exposure to acoustic sources or explosives, ship 
strike, and impacts to marine mammal habitat. Specifically, the Navy 
would use a combination of delayed starts, powerdowns, and shutdowns to 
avoid mortality or serious injury, minimize the likelihood or severity 
of PTS or other injury, and reduce instances of TTS or more severe 
behavioral disruption caused by acoustic sources or explosives. The 
Navy 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.
    The Navy assessed the practicability of the proposed measures in 
the context of personnel safety, practicality of implementation, and 
their impacts on the Navy's ability to meet their Title 10 requirements 
and found that the measures are supportable. As described in more 
detail below, NMFS has independently evaluated the measures the Navy 
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 will 
significantly and adequately reduce impacts on the affected marine 
mammal species and stocks and their habitat and, further, be 
practicable for Navy implementation. Therefore, the mitigation measures 
assure that the Navy's activities will have the least practicable 
adverse impact on the species or stocks and their habitat.
    The Navy also evaluated numerous measures in the 2019 NWTT DSEIS/
OEIS that were not included in the Navy's rulemaking/LOA application, 
and NMFS independently reviewed and preliminarily concurs with the 
Navy's analysis that their inclusion was not appropriate under the 
least practicable adverse impact standard based on our assessment. The 
Navy considered these additional potential mitigation measures in two 
groups. First, Chapter 5 (Mitigation) of the 2019 NWTT DSEIS/OEIS, in 
the Measures Considered but Eliminated section, includes 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. 
Appendix K (Geographic Mitigation Assessment) of the 2019 NWTT DSEIS/
OEIS includes an in-depth analysis of

[[Page 33991]]

time/area restrictions that have been recommended over time or 
previously implemented as a result of litigation (outside of the NWTT 
Study Area). As described in Chapter 5 (Mitigation) of the 2019 NWTT 
DSEIS/OEIS, commenters sometimes recommend that the Navy reduce its 
overall amount of training, reduce explosive use, modify its sound 
sources, completely replace live training with computer simulation, or 
include 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 2019 NWTT DSEIS/
OEIS, the Navy needs to train and test in the conditions in which it 
fights--and these types of modifications fundamentally change the 
activity in a manner that would not support the purpose and need for 
the training and testing (i.e., are entirely impracticable) and 
therefore are not considered further. NMFS finds the Navy's explanation 
for why adoption of these recommendations would unacceptably undermine 
the purpose of the testing and training persuasive. After independent 
review, NMFS finds Navy's judgment on the impacts of potential 
mitigation measures to personnel safety, practicality of 
implementation, and the effectiveness of training and testing within 
the NWTT Study Area persuasive, and for these reasons, NMFS finds that 
these measures do not meet the least practicable adverse impact 
standard because they are not practicable.
    Second, in Chapter 5 (Mitigation) of the 2019 NWTT DSEIS/OEIS, the 
Navy evaluated additional potential procedural 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 Navy's analysis, the measures would have significant direct 
negative effects on mission effectiveness and are considered 
impracticable (see Chapter 5 Mitigation of 2019 NWTT DSEIS/OEIS). NMFS 
independently reviewed the Navy's 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.
    Last, Appendix K (Geographic Mitigation Assessment) of the 2019 
NWTT DSEIS/OEIS describes a comprehensive method for analyzing 
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 that area for 
training, considering proximity to training ranges and emergency 
landing fields and other issues). For most of the areas that were 
considered in the 2019 NWTT DSEIS/OEIS but not included in this rule, 
the Navy found that the mitigation was not warranted because the 
anticipated reduction of adverse impacts on marine mammal species and 
their habitat was not sufficient to offset the impracticability of 
implementation. 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 Navy's analysis in Chapter 5 Mitigation and 
Appendix K Geographic Mitigation Assessment of the 2019 NWTT DSEIS/
OEIS, which considers 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 Navy ruled out in the 2019 NWTT DSEIS/
OEIS. Below are the mitigation measures that NMFS determined will 
ensure the least practicable adverse impact on all affected species and 
their habitat, including the specific considerations for military 
readiness activities. The following sections describe the mitigation 
measures that would be implemented in association with the training and 
testing activities analyzed in this document. The mitigation measures 
are organized into two categories: Procedural mitigation and mitigation 
areas.

Procedural Mitigation

    Procedural mitigation is mitigation that the Navy would implement 
whenever and wherever an applicable training or testing activity takes 
place within the NWTT Study Area. The Navy customizes procedural 
mitigation for each applicable activity category or stressor. 
Procedural mitigation generally involves: (1) The use of one or more 
trained Lookouts to diligently observe for specific biological 
resources (including marine mammals) within a mitigation zone, (2) 
requirements for Lookouts to immediately communicate sightings of 
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 first procedural 
mitigation (Table 35) is designed to aid Lookouts and other applicable 
Navy personnel with their observation, environmental compliance, and 
reporting responsibilities. The remainder of the procedural mitigation 
measures (Tables 36 through 49) are organized by stressor type and 
activity category and include acoustic stressors (i.e., active sonar, 
weapons firing noise), explosive stressors (i.e., sonobuoys, torpedoes, 
medium-caliber and large-caliber projectiles, missiles, bombs, mine 
counter-measure and neutralization activities, mine neutralization 
involving Navy divers), and physical disturbance and strike stressors 
(i.e., vessel movement, towed in-water devices, small-, medium-, and 
large-caliber non-explosive practice munitions, non-explosive missiles, 
non-explosive bombs and mine shapes).

     Table 35--Procedural Mitigation for Environmental Awareness and
                                Education
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     All training and testing activities, as applicable.
Mitigation Requirements:
     Appropriate personnel (including civilian personnel)
     involved in mitigation and training or testing activity reporting
     under the specified activities will 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:

[[Page 33992]]

 
        --Introduction to the U.S. Navy 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 Navy training and testing
         activities. The material explains why environmental compliance
         is important in supporting the Navy's 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.
        --U.S. Navy 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 software tool.
        --U.S. Navy 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.
------------------------------------------------------------------------

Procedural Mitigation for Acoustic Stressors
    Mitigation measures for acoustic stressors are provided in Tables 
36 and 37.
Procedural Mitigation for Active Sonar
    Procedural mitigation for active sonar is described in Table 36 
below.

            Table 36--Procedural Mitigation for Active Sonar
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Low-frequency active sonar, mid-frequency active sonar,
     high-frequency active sonar:
        --For vessel-based active sonar activities, mitigation applies
         only to sources that are positively controlled and deployed
         from manned surface vessels (e.g., sonar sources towed from
         manned surface platforms).
        --For aircraft-based active sonar activities, mitigation applies
         only to sources that are positively controlled and deployed
         from manned aircraft that do not operate at high altitudes
         (e.g., rotary-wing aircraft). Mitigation does not apply to
         active sonar sources deployed from unmanned aerial systems or
         aircraft operating at high altitudes (e.g., maritime patrol
         aircraft).
Number of Lookouts and Observation Platform:
     Hull-mounted sources:
        --1 Lookout: Platforms with space or manning restrictions while
         underway (at the forward part of a small boat or ship) and
         platforms using active sonar while moored or at anchor
         (including pierside).
        --2 Lookouts: Platforms without space or manning restrictions
         while underway (at the forward part of the ship).
     Sources that are not hull-mounted:
        --1 Lookout on the ship or aircraft conducting the activity.
Mitigation Requirements:
     Mitigation zones:
        --1,000 yd power down, 500 yd power down, and 200 yd or 100 yd
         shut down for low-frequency active sonar >=200 decibels (dB)
         and hull-mounted mid-frequency active sonar.
        --200 yd or 100 yd shut down for low-frequency active sonar <200
         dB, mid-frequency active sonar sources that are not hull-
         mounted, and high-frequency active sonar.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of active sonar transmission.
     During the activity:
        --Low-frequency active sonar >=200 decibels (dB) and hull-
         mounted mid-frequency active sonar: Observe the mitigation zone
         for marine mammals; power down active sonar transmission by 6
         dB if a marine mammal is observed within 1,000 yd of the sonar
         source; power down an additional 4 dB (10 dB total) if a marine
         mammal is observed within 500 yd; cease transmission if a
         cetacean in the NWTT Offshore Area, NWTT Inland Area, or
         Western Behm Canal is observed within 200 yd; cease
         transmission if a pinniped in the NWTT Offshore Area or Western
         Behm Canal is observed within 200 yd and cease transmission if
         a pinniped in NWTT Inland Waters is observed within 100 yd
         (except if hauled out on, or in the water near, man-made
         structures and vessels).
        --Low-frequency active sonar <200 dB, mid-frequency active sonar
         sources that are not hull-mounted, and high-frequency active
         sonar: Observe the mitigation zone for marine mammals; cease
         transmission if a cetacean or pinniped in the NWTT Offshore
         Area or Western Behm Canal is observed within 200 yd of the
         sonar source; cease transmission if a pinniped in NWTT Inland
         Waters is observed within 100 yd (except if hauled out on, or
         in the water near, man-made structures and vessels).
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:

[[Page 33993]]

 
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone 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) until one of the
         following conditions has been met: (1) The animal is observed
         exiting the mitigation zone; (2) the animal is thought to have
         exited the mitigation zone based on a determination of its
         course, speed, and movement relative to the sonar source; (3)
         the mitigation zone has been clear from any additional
         sightings for 10 minutes for aircraft-deployed sonar sources or
         30 minutes for vessel-deployed sonar sources; (4) for mobile
         activities, the active sonar source has transited a distance
         equal to double that of the mitigation zone size beyond the
         location of the last sighting; or (5) for activities using hull-
         mounted sonar, the Lookout concludes that dolphins are
         deliberately closing in on the ship to ride the ship's bow
         wave, and are therefore out of the main transmission axis of
         the sonar (and there are no other marine mammal sightings
         within the mitigation zone).
------------------------------------------------------------------------

Procedural Mitigation for Weapons Firing Noise
    Procedural mitigation for weapons firing noise is described in 
Table 37 below.

        Table 37--Procedural Mitigation for Weapons Firing Noise
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Weapons firing noise associated with large-caliber gunnery
     activities.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on the ship conducting the firing;
        --Depending on the activity, the Lookout could be the same one
         described in Table 40 for Explosive Medium-Caliber and Large-
         Caliber Projectiles or Table 47 for Small-, Medium-, and Large-
         Caliber Non-Explosive Practice Munitions.
Mitigation Requirements:
     Mitigation zone:
        --30[deg] on either side of the firing line out to 70 yd from
         the muzzle of the weapon being fired.
     Prior to the initial start of the activity:
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of weapons firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease weapons firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         weapons firing) until one of the following conditions has been
         met: (1) The animal is observed exiting the mitigation zone;
         (2) the animal is thought to have exited the mitigation zone
         based on a determination of its course, speed, and movement
         relative to the firing ship; (3) the mitigation zone has been
         clear from any additional sightings for 30 minutes; or (4) for
         mobile activities, the firing ship has transited a distance
         equal to double that of the mitigation zone size beyond the
         location of the last sighting.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Stressors
    Mitigation measures for explosive stressors are provided in Tables 
38 through 44.
Procedural Mitigation for Explosive Sonobuoys
    Procedural mitigation for explosive sonobuoys is described in Table 
38 below.

         Table 38--Procedural Mitigation for Explosive Sonobuoys
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive sonobuoys.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft or on a small boat.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zone:
        --600 yd. around an explosive sonobuoy.
     Prior to the initial start of the activity (e.g., during
     deployment of a sonobuoy field, which typically lasts 20-30
     minutes):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Conduct passive acoustic monitoring for marine mammals; use
         information from detections to assist visual observations.
        --Visually observe the mitigation zone for marine mammals; if
         observed, relocate or delay the start of sonobuoy or source/
         receiver pair detonations.

[[Page 33994]]

 
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease sonobuoy or source/receiver pair detonations.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following conditions has been
         met: (1) The animal is observed exiting the mitigation zone;
         (2) the animal is thought to have exited the mitigation zone
         based on a determination of its course, speed, and movement
         relative to the sonobuoy; or (3) the mitigation zone has been
         clear from any additional sightings for 10 minutes when the
         activity involves aircraft that have fuel constraints, or 30
         minutes when the activity involves aircraft that are not
         typically fuel constrained.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe for marine mammals in the vicinity of where detonations
         occurred; if any injured or dead marine mammals are observed,
         follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Torpedoes
    Procedural mitigation for explosive torpedoes is described in Table 
39 below.

         Table 39--Procedural Mitigation for Explosive Torpedoes
------------------------------------------------------------------------
                    Procedural Mitigation Description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive torpedoes.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zone:
        --2,100 yd around the intended impact location.
     Prior to the initial start of the activity (e.g., during
     deployment of the target):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Conduct passive acoustic monitoring for marine mammals; use
         information from detections to assist visual observations.
        --Visually observe the mitigation zone for marine mammals; if
         observed, relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; or (3) the mitigation zone has
         been clear from any additional sightings for 10 minutes when
         the activity involves aircraft that have fuel constraints, or
         30 minutes when the activity involves aircraft that are not
         typically fuel constrained.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe for marine mammals in the vicinity of where detonations
         occurred; if any injured or dead marine mammals are observed,
         follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Medium-Caliber and Large-Caliber 
Projectiles
    Procedural mitigation for Explosive Medium-Caliber and Large-
Caliber Projectiles is described in Table 40 below.

[[Page 33995]]



 Table 40--Procedural Mitigation for Explosive Medium-Caliber and Large-
                           Caliber Projectiles
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Gunnery activities using explosive medium-caliber and large-
     caliber projectiles:
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout on the vessel conducting the activity:
        --For activities using explosive large-caliber projectiles,
         depending on the activity, the Lookout could be the same as the
         one described in Table 37 for Weapons Firing Noise.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zones:
        --600 yd around the intended impact location for explosive
         medium-caliber projectiles.
        --1,000 yd around the intended impact location for explosive
         large-caliber projectiles.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; (3) the mitigation zone has been
         clear from any additional sightings for 30 minutes for vessel-
         based firing; or (4) for activities using mobile targets, the
         intended impact location has transited a distance equal to
         double that of the mitigation zone size beyond the location of
         the last sighting.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe for marine mammals in the vicinity of where detonations
         occurred; if any injured or dead marine mammals are observed,
         follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Missiles
    Procedural mitigation for explosive missiles is described in Table 
41 below.

         Table 41--Procedural Mitigation for Explosive Missiles
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Aircraft-deployed explosive missiles:
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zone:
        --2,000 yd around the intended impact location.
     Prior to the initial start of the activity (e.g., during a
     fly-over of the mitigation zone):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; or (3) the mitigation zone has
         been clear from any additional sightings for 10 minutes when
         the activity involves aircraft that have fuel constraints, or
         30 minutes when the activity involves aircraft that are not
         typically fuel constrained.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe for marine mammals in the vicinity of where detonations
         occurred; if any injured or dead marine mammals are observed,
         follow established incident reporting procedures.

[[Page 33996]]

 
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Bombs
    Procedural mitigation for explosive bombs is described in Table 42 
below.

           Table 42--Procedural Mitigation for Explosive Bombs
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive bombs.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in the aircraft conducting the
     activity.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zone:
        --2,500 yd around the intended target.
     Prior to the initial start of the activity (e.g., when
     arriving on station):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of bomb deployment.
     During the activity (e.g., during target approach):
        --Observe the mitigation zone for marine mammals; if observed,
         cease bomb deployment.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         bomb deployment) until one of the following conditions has been
         met: (1) The animal is observed exiting the mitigation zone;
         (2) the animal is thought to have exited the mitigation zone
         based on a determination of its course, speed, and movement
         relative to the intended target; (3) the mitigation zone has
         been clear from any additional sightings for 10 minutes; or (4)
         for activities using mobile targets, the intended target has
         transited a distance equal to double that of the mitigation
         zone size beyond the location of the last sighting.
     After completion of the activity (e.g., prior to
     maneuvering off station):
        --When practical (e.g., when platforms are not constrained by
         fuel restrictions or mission-essential follow-on commitments),
         observe for marine mammals in the vicinity of where detonations
         occurred; if any injured or dead marine mammals are observed,
         follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Mine Countermeasure and 
Neutralization Activities
    Procedural mitigation for explosive mine countermeasure and 
neutralization activities is described in Table 43 below.

  Table 43--Procedural Mitigation for Explosive Mine Countermeasure and
                        Neutralization Activities
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive mine countermeasure and neutralization
     activities.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on a vessel or in an aircraft when
     implementing the smaller mitigation zone.
     2 Lookouts (one positioned in an aircraft and one on a
     small boat) when implementing the larger mitigation zone.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zones:
        --600 yd around the detonation site for activities using <=5 lb
         net explosive weight.
        --2,100 yd around the detonation site for activities using >5-60
         lb net explosive weight.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station; typically, 10 minutes when the activity
     involves aircraft that have fuel constraints, or 30 minutes when
     the activity involves aircraft that are not typically fuel
     constrained):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of detonations.
     During the activity:

[[Page 33997]]

 
        --Observe for marine mammals; if observed, cease detonations.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following conditions has been
         met: (1) The animal is observed exiting the mitigation zone;
         (2) the animal is thought to have exited the mitigation zone
         based on a determination of its course, speed, and movement
         relative to detonation site; or (3) the mitigation zone has
         been clear from any additional sightings for 10 minutes when
         the activity involves aircraft that have fuel constraints, or
         30 minutes when the activity involves aircraft that are not
         typically fuel constrained.
     After completion of the activity (typically 10 minutes when
     the activity involves aircraft that have fuel constraints, or 30
     minutes when the activity involves aircraft that are not typically
     fuel constrained):
        --Observe for marine mammals in the vicinity of where
         detonations occurred; if any injured or dead marine mammals are
         observed, follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
------------------------------------------------------------------------

Procedural Mitigation for Explosive Mine Neutralization Activities 
lnvolving Navy Divers
    Procedural mitigation for explosive mine neutralization activities 
involving Navy divers is described in Table 44 below.

    Table 44--Procedural Mitigation for Explosive Mine Neutralization
                    Activities Involving Navy Divers
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Explosive mine neutralization activities involving Navy
     divers.
Number of Lookouts and Observation Platform:
     2 Lookouts on two small boats with one Lookout each, one of
     which will be a Navy biologist.
     All divers placing the charges on mines will support the
     Lookouts while performing their regular duties and will report
     applicable sightings to the lead Lookout, the supporting small
     boat, or the Range Safety Officer.
     If additional platforms are participating in the activity,
     personnel positioned in those assets (e.g., safety observers,
     evaluators) will support observing the mitigation zone for marine
     mammals while performing their regular duties.
Mitigation Requirements:
     Mitigation zone:
        --500 yd around the detonation site during activities using >0.5-
         2.5 lb net explosive weight.
     Prior to the initial start of the activity (starting 30
     minutes before the first planned detonation):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of detonations.
        --The Navy will ensure the area is clear of marine mammals for
         30 minutes prior to commencing a detonation.
        --A Navy biologist will serve as the lead Lookout and will make
         the final determination that the mitigation zone is clear of
         any biological resource sightings prior to the commencement of
         a detonation. The Navy biologist will maintain radio
         communication with the unit conducting the event and the other
         Lookout.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease detonations.
        --To the maximum extent practicable depending on mission
         requirements, safety, and environmental conditions, boats will
         position themselves near the midpoint of the mitigation zone
         radius (but outside of the detonation plume and human safety
         zone), will position themselves on opposite sides of the
         detonation location, and will travel in a circular pattern
         around the detonation location with one Lookout observing
         inward toward the detonation site and the other observing
         outward toward the perimeter of the mitigation zone.
        --The Navy will use only positively controlled charges (i.e., no
         time-delay fuses).
        --The Navy will use the smallest practicable charge size for
         each activity.
        --Activities will be conducted in Beaufort sea state number 2
         conditions or better and will not be conducted in low
         visibility conditions.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         detonations) until one of the following conditions has been
         met: (1) The animal is observed exiting the mitigation zone;
         (2) the animal is thought to have exited the mitigation zone
         based on a determination of its course, speed, and movement
         relative to the detonation site; or (3) the mitigation zone has
         been clear from any additional sightings for 30 minutes.
     After each detonation and the completion of an activity
     (for 30 minutes):
        --Observe for marine mammals in the vicinity of where
         detonations occurred and immediately downstream of the
         detonation location; if any injured or dead marine mammals are
         observed, follow established incident reporting procedures.
        --If additional platforms are supporting this activity (e.g.,
         providing range clearance), these assets will assist in the
         visual observation of the area where detonations occurred.
     Additional requirements:
        --At the Hood Canal Explosive Ordnance Disposal Range and
         Crescent Harbor Explosive Ordnance Disposal Range, naval units
         will obtain permission from the appropriate designated Command
         authority prior to conducting explosive mine neutralization
         activities involving the use of Navy divers.

[[Page 33998]]

 
        --At the Hood Canal Explosive Ordnance Disposal Range, during
         February, March, and April (the juvenile migration period for
         Hood Canal Summer Run Chum), the Navy will not use explosives
         in bin E3 (>0.5-2.5 lb net explosive weight), and will instead
         use explosives in bin E0 (<0.1 lb net explosive weight).
        --At the Hood Canal Explosive Ordnance Disposal Range, during
         August, September, and October (the adult migration period for
         Hood Canal summer-run chum and Puget Sound Chinook), the Navy
         will avoid the use of explosives in bin E3 (>0.5-2.5 lb net
         explosive weight), and will instead use explosive bin E0 (<0.1
         lb net explosive weight) to the maximum extent practicable
         unless necessitated by mission requirements.
        --At the Crescent Harbor Explosive Ordnance Disposal Range, the
         Navy will conduct explosive activities at least 1,000 m from
         the closest point of land to avoid or reduce impacts on fish
         (e.g., bull trout) in nearshore habitat areas.
------------------------------------------------------------------------

Procedural Mitigation for Physical Disturbance and Strike Stressors
    Mitigation measures for physical disturbance and strike stressors 
are provided in Tables 45 through 49.
Procedural Mitigation for Vessel Movement
    Procedural mitigation for vessel movement is described in Table 45 
below.

           Table 45--Procedural Mitigation for Vessel Movement
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Vessel movement:
        --The mitigation will not be applied if: (1) The vessel's safety
         is threatened, (2) the vessel is restricted in its ability to
         maneuver (e.g., during launching and recovery of aircraft or
         landing craft, during towing activities, when mooring, during
         Transit Protection Program exercises or other events involving
         escort vessels), (3) the vessel is operated autonomously, or
         (4) when impractical based on mission requirements (e.g.,
         during test body retrieval by range craft).
Number of Lookouts and Observation Platform:
     1 Lookout on the vessel that is underway.
Mitigation Requirements:
     Mitigation zones:
        --500 yd (for surface ships other than small boats) around
         whales.
        --200 yd (for surface ships other than small boats) around all
         marine mammals other than whales (except bow-riding dolphins
         and pinnipeds hauled out on man-made navigational structures,
         port structures, and vessels).
        --100 yd (for small boats, such as range craft) around marine
         mammals (except bow-riding dolphins and pinnipeds hauled out on
         man-made navigational structures, port structures, and
         vessels).
     During the activity:
        --When underway, observe the mitigation zone for marine mammals;
         if observed, maneuver to maintain distance.
     Additional requirements:
        --Prior to Small Boat Attack exercises at Naval Station Everett,
         Naval Base Kitsap Bangor, or Naval Base Kitsap Bremerton, Navy
         event planners will coordinate with Navy biologists during the
         event planning process. Navy biologists will work with NMFS to
         determine the likelihood of marine mammal presence in the
         planned training location. Navy biologists will notify event
         planners of the likelihood of species presence as they plan
         specific details of the event (e.g., timing, location,
         duration). The Navy will provide additional environmental
         awareness training to event participants. The training will
         alert participating ship and aircraft crews to the possible
         presence of marine mammals in the training location. Lookouts
         will use the information to assist their visual observation of
         applicable mitigation zones and to aid in the implementation of
         procedural mitigation.
        --If a marine mammal vessel strike occurs, the Navy will follow
         the established incident reporting procedures.
------------------------------------------------------------------------

Procedural Mitigation for Towed In-Water Devices

       Table 46--Procedural Mitigation for Towed In-Water Devices
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Towed in-water devices:
        --Mitigation applies to devices towed from a manned surface
         platform or manned aircraft, or when a manned support craft is
         already participating in an activity involving in-water devices
         being towed by unmanned platforms.
        --The mitigation will not be applied if the safety of the towing
         platform or in-water device is threatened.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on the towing platform or support
     craft.
Mitigation Requirements:
     Mitigation zones:
        --250 yd (for in-water devices towed by aircraft or surface
         ships other than small boats) around marine mammals (except bow-
         riding dolphins and pinnipeds hauled out on man-made
         navigational structures, port structures, and vessels).

[[Page 33999]]

 
        --100 yd (for in-water devices towed by small boats, such as
         range craft) around marine mammals (except bow-riding dolphins
         and pinnipeds hauled out on man-made navigational structures,
         port structures, and vessels).
     During the activity (i.e., when towing an in-water device):
        --Observe the mitigation zone for marine mammals; if observed,
         maneuver to maintain distance.
------------------------------------------------------------------------

Procedural Mitigation for Small-, Medium-, and Large-Caliber Non-
Explosive Practice Munitions

 Table 47--Procedural Mitigation for Small-, Medium-, and Large-Caliber
                    Non-Explosive Practice Munitions
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Gunnery activities using small-, medium-, and large-caliber
     non-explosive practice munitions:
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout positioned on the platform conducting the
     activity.
     Depending on the activity, the Lookout could be the same as
     the one described in Table 37 for Weapons Firing Noise.
Mitigation Requirements:
     Mitigation zone:
        --200 yd around the intended impact location.
     Prior to the initial start of the activity (e.g., when
     maneuvering on station):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting before or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; (3) the mitigation zone has been
         clear from any additional sightings for 10 minutes for aircraft-
         based firing or 30 minutes for vessel-based firing; or (4) for
         activities using a mobile target, the intended impact location
         has transited a distance equal to double that of the mitigation
         zone size beyond the location of the last sighting.
------------------------------------------------------------------------

Procedural Mitigation for Non-Explosive Missiles

       Table 48--Procedural Mitigation for Non-Explosive Missiles
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Aircraft-deployed non-explosive missiles:
        --Mitigation applies to activities using a surface target.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
Mitigation Requirements:
     Mitigation zone:
        --900 yd around the intended impact location.
     Prior to the initial start of the activity (e.g., during a
     fly-over of the mitigation zone):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of firing.
     During the activity:
        --Observe the mitigation zone for marine mammals; if observed,
         cease firing.
     Commencement/recommencement conditions after a marine
     mammal sighting prior to or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         firing) until one of the following conditions has been met: (1)
         The animal is observed exiting the mitigation zone; (2) the
         animal is thought to have exited the mitigation zone based on a
         determination of its course, speed, and movement relative to
         the intended impact location; or (3) the mitigation zone has
         been clear from any additional sightings for 10 minutes when
         the activity involves aircraft that have fuel constraints, or
         30 minutes when the activity involves aircraft that are not
         typically fuel constrained.
------------------------------------------------------------------------


[[Page 34000]]

Procedural Mitigation for Non-Explosive Bombs and Mine Shapes

 Table 49--Procedural Mitigation for Non-Explosive Bombs and Mine Shapes
------------------------------------------------------------------------
                    Procedural mitigation description
-------------------------------------------------------------------------
Stressor or Activity:
     Non-explosive bombs.
     Non-explosive mine shapes during mine laying activities.
Number of Lookouts and Observation Platform:
     1 Lookout positioned in an aircraft.
Mitigation Requirements:
     Mitigation zone:
        --1,000 yd around the intended target.
     Prior to the initial start of the activity (e.g., when
     arriving on station):
        --Observe the mitigation zone for floating vegetation; if
         observed, relocate or delay the start until the mitigation zone
         is clear.
        --Observe the mitigation zone for marine mammals; if observed,
         relocate or delay the start of bomb deployment or mine laying.
     During the activity (e.g., during approach of the target or
     intended minefield location):
        --Observe the mitigation zone for marine mammals; if observed,
         cease bomb deployment or mine laying.
     Commencement/recommencement conditions after a marine
     mammal sighting prior to or during the activity:
        --The Navy will allow a sighted marine mammal to leave the
         mitigation zone prior to the initial start of the activity (by
         delaying the start) or during the activity (by not recommencing
         bomb deployment or mine laying) until one of the following
         conditions has been met: (1) The animal is observed exiting the
         mitigation zone; (2) the animal is thought to have exited the
         mitigation zone based on a determination of its course, speed,
         and movement relative to the intended target or minefield
         location; (3) the mitigation zone has been clear from any
         additional sightings for 10 minutes; or (4) for activities
         using mobile targets, the intended target has transited a
         distance equal to double that of the mitigation zone size
         beyond the location of the last sighting.
------------------------------------------------------------------------

Mitigation Areas

    In addition to procedural mitigation, the Navy would implement 
mitigation measures within mitigation areas to avoid or minimize 
potential impacts on marine mammals. A full technical analysis (for 
which the methods were summarized above) of the mitigation areas that 
the Navy considered for marine mammals is provided in Appendix K 
(Geographic Mitigation Assessment) of the 2019 NWTT DSEIS/OEIS. The 
Navy took into account public comments received on the 2019 NWTT DSEIS/
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 2015-2020 regulations to further reduce impacts to 
marine mammals.
    Information on the mitigation measures that the Navy will implement 
within mitigation areas is provided in Table 50 (see below). The 
mitigation applies year-round unless specified otherwise in the table.
    NMFS conducted an independent analysis of the mitigation areas that 
the Navy proposed, which are described below. NMFS preliminarily 
concurs with the Navy's analysis, which indicates that the measures in 
these mitigation areas are both practicable and will reduce the 
likelihood or severity of adverse impacts to marine mammal species or 
their habitat in the manner described in the Navy's analysis and this 
rule. NMFS is heavily reliant on the Navy's description of operational 
practicability, since the Navy is best equipped to describe the degree 
to which a given mitigation measure affects personnel safety or mission 
effectiveness, and is practical to implement. The Navy considers 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 or severity of adverse 
impacts to marine mammal species or their habitat in the Preliminary 
Analysis and Negligible Impact Determination section.

  Table 50--Geographic Mitigation Areas for Marine Mammals in the NWTT
                               Study Area
------------------------------------------------------------------------
                       Mitigation area description
-------------------------------------------------------------------------
Stressor or Activity:
     Sonar.
     Explosives.
     Physical disturbance and strikes.
Mitigation Requirements:
     Marine Species Coastal Mitigation Area (year-round):
        --Within 50 nmi from shore in the Marine Species Coastal
         Mitigation Area, the Navy will not conduct: (1) Explosive
         training activities, (2) explosive testing activities (with the
         exception of explosive Mine Countermeasure and Neutralization
         Testing activities), and (3) non-explosive missile training
         activities. Should national security present a requirement to
         conduct these activities in the mitigation area, naval units
         will obtain permission from the appropriate designated Command
         authority prior to commencement of the activity. The Navy will
         provide NMFS with advance notification and include information
         about the event in its annual activity reports to NMFS.
        --Within 20 nmi from shore in the Marine Species Coastal
         Mitigation Area, the Navy will not conduct non-explosive large-
         caliber gunnery training activities and non-explosive bombing
         training activities. Should national security present a
         requirement to conduct these activities in the mitigation area,
         naval units will obtain permission from the appropriate
         designated Command authority prior to commencement of the
         activity. The Navy will provide NMFS with advance notification
         and include information about the event in its annual activity
         reports to NMFS.

[[Page 34001]]

 
        --Within 12 nmi from shore in the Marine Species Coastal
         Mitigation Area, the Navy will not conduct: (1) Non-explosive
         small- and medium-caliber gunnery training activities, (2) non-
         explosive torpedo training activities, and (3) Anti-Submarine
         Warfare Tracking Exercise--Helicopter, Maritime Patrol
         Aircraft, Ship, or Submarine training activities. Should
         national security present a requirement to conduct these
         activities in the mitigation area, naval units will obtain
         permission from the appropriate designated Command authority
         prior to commencement of the activity. The Navy will provide
         NMFS with advance notification and include information about
         the event in its annual activity reports to NMFS.
     Olympic Coast National Marine Sanctuary Mitigation Area
     (year-round):
        --Within the Olympic Coast National Marine Sanctuary Mitigation
         Area, the Navy will not conduct more than 32 hours of MF1 mid-
         frequency active sonar during training annually and will not
         conduct non-explosive bombing training activities. Should
         national security present a requirement to conduct more than 32
         hours of MF1 mid-frequency active sonar during training
         annually or conduct non-explosive bombing training activities
         in the mitigation area, naval units will obtain permission from
         the appropriate designated Command authority prior to
         commencement of the activity. The Navy will provide NMFS with
         advance notification and include information about the event in
         its annual activity reports to NMFS.
        --Within the Olympic Coast National Marine Sanctuary Mitigation
         Area, the Navy will not conduct more than 33 hours of MF1 mid-
         frequency active sonar during testing annually (except within
         the portion of the mitigation area that overlaps the Quinault
         Range Site) and will not conduct explosive Mine Countermeasure
         and Neutralization Testing activities. Should national security
         present a requirement for the Navy to conduct more than 33
         hours of MF1 mid-frequency active sonar during testing annually
         (except within the portion of the mitigation area that overlaps
         the Quinault Range Site) or conduct explosive Mine
         Countermeasure and Neutralization Testing activities in the
         mitigation area, naval units will obtain permission from the
         appropriate designated Command authority prior to commencement
         of the activity. The Navy will provide NMFS with advance
         notification and include information about the event in its
         annual activity reports to NMFS.
     Stonewall and Heceta Bank Humpback Whale Mitigation Area
     (May 1-November 30):
        --Within the Stonewall and Heceta Bank Humpback Whale Mitigation
         Area, the Navy will not use MF1 mid-frequency active sonar or
         explosives during training and testing from May 1 to November
         30. Should national security present a requirement to use MF1
         mid-frequency active sonar or explosives during training and
         testing from May 1 to November 30, naval units will obtain
         permission from the appropriate designated Command authority
         prior to commencement of the activity. The Navy will provide
         NMFS with advance notification and include information about
         the event in its annual activity reports to NMFS.
     Point St. George Humpback Whale Mitigation Area (July 1-
     November 30):
        --Within the Point St. George Humpback Whale Mitigation Area,
         the Navy will not use MF1 mid-frequency active sonar or
         explosives during training and testing from July 1 to November
         30. Should national security present a requirement to use MF1
         mid-frequency active sonar or explosives during training and
         testing from July 1 to November 30, naval units will obtain
         permission from the appropriate designated Command authority
         prior to commencement of the activity. The Navy will provide
         NMFS with advance notification and include information about
         the event in its annual activity reports to NMFS.
     Puget Sound and Strait of Juan de Fuca Mitigation Area
     (year-round):
        --Within the Puget Sound and Strait of Juan de Fuca Mitigation
         Area, the Navy will require units to obtain approval from the
         appropriate designated Command authority prior to: (1) The use
         of hull-mounted mid-frequency active sonar during training
         while underway, and (2) conducting ship and submarine active
         sonar pierside maintenance or testing.
        --Within the Puget Sound and Strait of Juan de Fuca Mitigation
         Area for Civilian Port Defense--Homeland Security Anti-
         Terrorism/Force Protection Exercises, Navy event planners will
         coordinate with Navy biologists during the event planning
         process. Navy biologists will work with NMFS to determine the
         likelihood of gray whale and Southern Resident Killer Whale
         presence in the planned training location. Navy biologists will
         notify event planners of the likelihood of species presence as
         they plan specific details of the event (e.g., timing,
         location, duration). The Navy will ensure environmental
         awareness of event participants. Environmental awareness will
         help alert participating ship and aircraft crews to the
         possible presence of marine mammals in the training location,
         such as gray whales and Southern Resident Killer Whales.
     Northern Puget Sound Gray Whale Mitigation Area (March 1-
     May 31):
        --Within the Northern Puget Sound Gray Whale Mitigation Area,
         the Navy will not conduct Civilian Port Defense--Homeland
         Security Anti-Terrorism/Force Protection Exercises from March 1
         to May 31. Should national security present a requirement to
         conduct Civilian Port Defense--Homeland Security Anti-Terrorism/
         Force Protection Exercises from March 1 to May 31, naval units
         will obtain permission from the appropriate designated Command
         authority prior to commencement of the activity. The Navy will
         provide NMFS with advance notification and include information
         about the event in its annual activity reports to NMFS.
------------------------------------------------------------------------

BILLING CODE 3510-22-P

[[Page 34002]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.007

BILLING CODE 3510-22-C

[[Page 34003]]

Mitigation Conclusions

    NMFS has carefully evaluated the Navy's proposed mitigation 
measures--many of which were developed with NMFS' input during the 
previous phases of Navy training and testing authorizations but several 
of which are new since implementation of the current 2015 to 2020 
regulations--and considered a broad range of other measures (i.e., the 
measures considered but eliminated in the 2019 NWTT DSEIS/OEIS, which 
reflect many of the comments that have arisen via NMFS or public input 
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 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 Navy's proposed measures, as well as 
other measures considered by the Navy and NMFS, 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 Navy's 
activities and the proposed mitigation measures. While NMFS has 
preliminarily determined that the Navy's 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, the proposed 
mitigation measures may be refined, modified, removed, or added to 
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 in 
the NWTT Study Area for over 20 years, it developed a formal marine 
species monitoring program in support of the MMPA and ESA 
authorizations in 2009. This robust 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 
(www.navymarinespeciesmonitoring.us) and the data on the Ocean 
Biogeographic Information System Spatial Ecological Analysis of 
Megavertebrate Populations (OBIS-SEAMAP) (http://seamap.env.duke.edu/).
    The Navy will continue collecting monitoring data to inform our 
understanding of the occurrence of marine mammals in the NWTT Study 
Area; the likely exposure of marine mammals to stressors of concern in 
the NWTT 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 Navy 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 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 Navy through the regulatory process for previous Navy at-sea 
training and testing activities.

Integrated Comprehensive Monitoring Program

    The Navy's Integrated Comprehensive Monitoring Program (ICMP) is 
intended to coordinate marine species monitoring efforts across all 
regions and to allocate the most appropriate level and type of effort 
for each range complex based on a set of standardized objectives, and 
in acknowledgement of regional expertise and resource availability. The 
ICMP is designed to be flexible, scalable, and adaptable through the 
adaptive management and strategic planning processes to periodically 
assess progress and reevaluate objectives. This process includes 
conducting an annual adaptive management review meeting, at which the 
Navy and NMFS jointly consider the prior-year goals, monitoring 
results, and related scientific advances to determine if monitoring 
plan modifications are warranted to more effectively address program 
goals. Although the ICMP does not specify actual monitoring field work 
or individual projects, it does establish a matrix of goals and 
objectives that have been developed in coordination with NMFS. As the 
ICMP is implemented through the Strategic Planning Process, detailed 
and specific studies will be developed which support the Navy's and 
NMFS top-level monitoring goals. In essence, the ICMP directs that 
monitoring activities relating to the effects of Navy training and 
testing activities on marine species should be designed to contribute 
towards or accomplish 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 of 
species);
     An increase in the understanding of the nature, scope, or 
context of the

[[Page 34004]]

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 expended materials), through better understanding of one 
or more of the following: (1) The nature of the action and its 
surrounding environment (e.g., sound-source characterization, 
propagation, and ambient noise levels), (2) the affected species (e.g., 
life history or dive patterns), (3) the likely co-occurrence of marine 
mammals and ESA-listed marine species with the action (in whole or 
part), and (4) 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 (1) the long-term fitness 
and survival of an individual; or (2) 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 Navy complies with the incidental take regulations and LOAs and the 
ESA 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.

Strategic Planning Process for Marine Species Monitoring

    The Navy also developed the Strategic Planning Process for Marine 
Species Monitoring, which serves to guide the investment of resources 
to most efficiently address ICMP objectives and intermediate scientific 
objectives developed through this process. The Strategic Planning 
Process establishes the guidelines and processes necessary to develop, 
evaluate, and fund individual projects based on objective scientific 
study questions. The process uses an underlying framework designed 
around intermediate scientific objectives and a conceptual framework 
incorporating a progression of knowledge spanning occurrence, exposure, 
response, and consequence. The Strategic Planning Process for Marine 
Species Monitoring is used to set overarching intermediate scientific 
objectives; develop individual monitoring project concepts; evaluate, 
prioritize, and select specific monitoring projects to fund or continue 
supporting for a given fiscal year; execute and manage selected 
monitoring projects; and report and evaluate progress and results. This 
process addresses relative investments to different range complexes 
based on goals across all range complexes, and monitoring would 
leverage multiple techniques for data acquisition and analysis whenever 
possible. More information on the Strategic Planning Process for Marine 
Species Monitoring including results, reports, and publications, is 
also available online (http://www.navymarinespeciesmonitoring.us/).

Past and Current Monitoring in the NWTT Study Area

    The monitoring program has undergone significant changes since the 
first rule was issued for the NWTT Study Area in 2010, which highlights 
the monitoring program's evolution 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. This includes in the NWTT 
Study Area, for example, (a) satellite tagging of blue whales, fin 
whales, humpback whales, and Southern Resident killer whales; (b) 
analysis of existing passive acoustic monitoring datasets; and (c) 
line-transect aerial surveys for marine mammals in Puget Sound, 
Washington.
    Numerous publications, dissertations, and conference presentations 
have resulted from research conducted under the marine species 
monitoring program (https://www.navymarinespeciesmonitoring.us/reading-room/publications/), leading to a significant contribution to the body 
of marine mammal science. Publications on occurrence, distribution, and 
density 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 Office of Naval Research) 
and demonstration-validation (e.g., Living Marine Resources) 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 Atlantic Fleet Training and Testing Study Area in the 
Atlantic Ocean, and various other ranges. Publications from the Living 
Marine Resources and Office of Naval Research 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 procedural 
mitigations as monitoring. Data are collected by shipboard personnel on 
hours spent training, hours of observation, hours of sonar, and marine 
mammals 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

[[Page 34005]]

sonar use and explosive detonations within the NWTT 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 training and testing activities within the 
NWTT 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 typically supports 
several monitoring projects in the NWTT 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/. Projects can be either major multi-year efforts, or 
one to two-year special studies. The emphasis on monitoring in the 
Pacific Northwest is directed towards collecting and analyzing tagging 
data related to the occurrence of blue whales, fin whales, humpback 
whales, and Southern Resident killer whales. In 2017, researchers 
deployed 28 tags on blue whales and one tag on a fin whale off southern 
and central California (Mate et al., 2017). Detailed analyses for the 
2017 tagging effort are ongoing and will be available later in a final 
report and posted at https://www.navymarinespeciesmonitoring.us/. 
Humpback whales have been tagged with satellite tags, and biopsy 
samples have been collected (Mate et al., 2017). Location information 
on Southern Resident killer whales was provided via satellite tag data 
and acoustic detections (Hanson et al., 2018). Also, distribution of 
Chinook salmon (a key prey species of Southern Resident killer whales) 
in coastal waters from Alaska to Northern California was studied 
(Shelton et al., in review). Future monitoring efforts in the NWTT 
Study Area are anticipated to continue along the same objectives: 
Determining the species and populations of marine mammals present and 
potentially exposed to Navy training and testing activities in the NWTT 
Study Area, through tagging, passive acoustic monitoring, refined 
modeling, photo identification, biopsies, and visual monitoring.

Adaptive Management

    The proposed regulations governing the take of marine mammals 
incidental to Navy training and testing activities in the NWTT Study 
Area contain an adaptive management component. Our understanding of the 
effects of Navy training and testing 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 seven-year regulations.
    The reporting requirements associated with this 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 Navy 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: http://www.navymarinespeciesmonitoring.us.
    There are several different reporting requirements pursuant to the 
current regulations. All of these reporting requirements would be 
continued under this proposed rule for the seven-year period.

Notification of Injured, Live Stranded or Dead Marine Mammals

    The Navy 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 NWTT Monitoring Report

    The Navy would submit an annual report to NMFS of the NWTT 
monitoring describing the implementation and results from the previous 
calendar year. Data collection methods would be standardized across 
Pacific Range Complexes including the MITT, HSTT, NWTT, and Gulf of 
Alaska (GOA) Study Areas to allow for comparison in different 
geographic locations. The draft of the annual monitoring report would 
be submitted either three months after the end of the calendar year or 
three months after the conclusion of the monitoring year, to be 
determined by the Adaptive Management process. NMFS will submit 
comments or questions on the report, if any, within one month of 
receipt. The report will be considered final after the Navy has 
addressed NMFS' comments, or one month after submittal of the draft if 
NMFS does not provide comments on the draft report. Such a report would 
describe progress of knowledge made with respect to intermediate 
scientific objectives within the NWTT Study Area associated with the 
ICMP. Similar study questions would be treated together so that 
summaries can be provided for each topic area. The report need not 
include analyses and content that do not provide direct assessment of 
cumulative progress on the monitoring plan study questions. NMFS would 
submit comments on the draft monitoring report, if any, within three 
months of receipt. The report would be considered final after the Navy 
has addressed NMFS' comments, or three months after the submittal of 
the draft if NMFS does not have comments.
    As an alternative, the Navy may submit a Pacific-Range Complex 
annual

[[Page 34006]]

Monitoring Plan report to fulfill this requirement. Such a report 
describes progress of knowledge made with respect to monitoring study 
questions across multiple Navy ranges associated with the ICMP. Similar 
study questions would be treated together so that progress on each 
topic is summarized across multiple Navy ranges. The report need not 
include analyses and content that does not provide direct assessment of 
cumulative progress on the monitoring study question. This would 
continue to allow the Navy to provide a cohesive monitoring report 
covering multiple ranges (as per ICMP goals), rather than entirely 
separate reports for the NWTT, GOA, MITT, and HSTT Study Areas.

Annual NWTT Training Exercise Report and Testing Activity Reports

    Each year, the Navy would submit one preliminary report (Quick Look 
Report) to NMFS detailing the status of applicable sound sources within 
21 days after the anniversary of the date of issuance of the LOA. Each 
year, the Navy would also submit a detailed report (NWTT Annual 
Training Exercise Report and Testing Activity Report) to NMFS within 
three months after the one-year anniversary of the date of issuance of 
the LOA. NMFS will submit comments or questions on the report, if any, 
within one month of receipt. The report will be considered final after 
the Navy has addressed NMFS' comments, or one month after submittal of 
the draft if NMFS does not provide comments on the draft report. The 
annual report would contain 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 (missiles, bombs, 
sonobuoys, etc.) for each explosive bin). The annual report 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 report 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 NWTT EIS/OEIS and MMPA final rule. The 
annual report 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 final annual/close-out report at the conclusion of the 
authorization period (year seven) would also serve as the comprehensive 
close-out report and include both the final year annual use compared to 
annual authorization as well as a cumulative seven-year annual use 
compared to seven-year authorization. Information included in the 
annual reports may be used to inform future adaptive management of 
activities within the NWTT Study Area.
    The Annual NWTT Training Exercise Report and Testing Activity Navy 
report (classified or unclassified versions) could be consolidated with 
other exercise reports from other range complexes in the Pacific Ocean 
for a single Pacific Exercise Report, if desired.

Other Reporting and Coordination

    The Navy 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 
(currently, every two years a joint Pacific-Atlantic meeting is held); 
and
     Annual Adaptive Management meetings that also include the 
Marine Mammal Commission (recently modified to occur in conjunction 
with the annual monitoring technical review meeting).

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. For Level A 
harassment or Level B harassment (as presented in Tables 32 and 33), in 
addition to considering estimates of the number of marine mammals that 
might be taken 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 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 rise to the level 
of takes both annually and over the seven-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 to 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 serious injury or mortality (hereafter referred to as 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 Navy's 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 training 
and testing activities. The Description of the Specified Activity 
section describes annual activities. There may be some flexibility in 
the exact number of hours,

[[Page 34007]]

items, or detonations that may vary from year to year, but take totals 
would not exceed the maximum annual totals and seven-year totals 
indicated in Tables 32 and 33. 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 a 
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 Tables 32 and 33, given that some of the 
anticipated effects of the Navy's training and testing activities on 
marine mammals are expected to be relatively similar in nature. 
However, below that, we 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 Navy's 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 Navy's harassment take request is based on its model and 
quantitative assessment of mitigation, which NMFS reviewed and concurs 
appropriately predicts the maximum amount of harassment that is 
reasonably likely to occur. The model calculates sound energy 
propagation from sonar, other active acoustic sources, and explosives 
during naval 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 model intentionally err on the side of overestimation when 
there are unknowns. Naval activities are modeled as though they would 
occur regardless of proximity to marine mammals, meaning that no 
mitigation is considered (e.g., no power down or shut down) and without 
any avoidance of the activity by the animal. The final step of the 
quantitative analysis of acoustic effects, which occurs after the 
modeling (as described in the Estimated Take of Marine Mammals 
section), is to consider the implementation of mitigation and the 
possibility that marine mammals would avoid continued or repeated sound 
exposures. NMFS provided input to, independently reviewed, and 
concurred with the Navy on this process and the Navy's analysis, which 
is described in detail in Section 6 of the Navy's rulemaking/LOA 
application, was used to quantify harassment takes for this rule.
    Generally speaking, the Navy 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 evoke a response of equal 
magnitude (DeRuiter 2012). The estimated number of Level A harassment 
and Level B harassment takes does not equate to the number of 
individual animals the Navy expects 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 seven-year period. These instances may represent either 
brief exposures (seconds or minutes) or, in some cases, longer 
durations of exposure within a day. 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 to give us a 
relative sense of where a larger portion of a species is being taken by 
Navy activities, 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 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 a small subset of 
animals is being repeatedly taken over a high number of sequential 
days, the overall magnitude 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 very minimal impact) 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 Navy activities and the movement patterns of marine 
mammals, it is unlikely that individuals from most stocks would be 
taken over more than a few sequential days. 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 any individuals would be taken a 
significant portion of the days of the year, much less that many of the 
days of disturbance would be sequential.
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

[[Page 34008]]

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 Navy's 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.
Behavioral Response
    The estimates calculated using the behavioral response function do 
not differentiate between the different types of behavioral responses 
that rise to the level of Level B harassments. As described in the 
Navy's application, the Navy identified (with NMFS' input) the types of 
behaviors that would be considered a take (moderate behavioral 
responses as characterized in Southall et al. (2007) (e.g., altered 
migration paths or dive profiles, interrupted nursing, breeding or 
feeding, or avoidance) that also would be expected to continue for the 
duration of an exposure). The Navy 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 that are used to predict how many instances 
of Level B behavioral harassment occur in a day. Take estimates alone 
do not provide information regarding the potential fitness or other 
biological consequences of the reactions 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 training and testing 
activities would be primarily from ASW events. Unlike other Navy 
training and testing Study Areas, no major training exercises (MTEs) 
are proposed in the NWTT Study Area. In the range of potential 
behavioral effects that might expect to be 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 one 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. A less severe exposure of this nature 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 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.
    To help assess this, for sonar (LFAS/MFAS/HFAS) used in the NWTT 
Study Area, the Navy provided information estimating the percentage of 
animals that may be taken by Level B harassment under each behavioral 
response function that would occur within 6-dB increments (percentages 
discussed below in the Group and Species-Specific Analyses section). 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 (such as distance) are also 
important. The majority of Level B harassment takes are expected to be 
in the form of milder responses (i.e., lower-level exposures that still 
rise to the level of take, but would likely be less severe in the range 
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 Navy activities might necessarily be expected to 
potentially result in more severe responses (see the Group and Species-
Specific Analyses section below for more detailed information). To 
fully understand the likely impacts of the predicted/proposed 
authorized take on an individual (i.e., what is the likelihood or 
degree of fitness impacts), one must look closely at the available 
contextual information, such as the duration of likely exposures and 
the likely severity of the exposures (e.g., whether they will occur for 
a longer duration over sequential days or the comparative sound level 
that will be received). Ellison et al. (2012) and Moore and Barlow 
(2013), among others emphasize the importance of context (e.g., 
behavioral state of the animals, distance from the sound source, etc.) 
in evaluating behavioral responses of marine mammals to acoustic 
sources.
Diel Cycle
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing on a diel cycle (24-hour cycle). Behavioral 
reactions 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 reactions 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 
ASW activities, typically include vessels that are continuously moving 
at speeds typically 10-15 kn, or higher, and likely cover large areas 
that are relatively far from shore (typically more than 3 nmi from 
shore) and in waters greater than 600 ft deep. Additionally marine 
mammals are

[[Page 34009]]

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 Navy does 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 Navy conducts 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 Appendix A (Navy Activity 
Descriptions) of the 2019 NWTT DSEIS/OEIS. Sonar used during ASW would 
impart the greatest amount of acoustic energy of any category of sonar 
and other transducers analyzed in the Navy's rulemaking/LOA application 
and include hull-mounted, towed, line array, sonobuoy, helicopter 
dipping, and torpedo sonars. Most ASW sonars are MFAS (1-10 kHz); 
however, some sources may use higher or lower frequencies. ASW training 
activities using hull mounted sonar proposed for the NWTT Study Area 
generally last for only a few hours (see Table 3). Some ASW testing 
activities range from several hours, to days, to up to 3 weeks for 
Pierside-Sonar Testing and Submarine Sonar Testing/Maintenance (see 
Table 4). 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 
does not typically conduct successive ASW exercises in the same 
locations. Given the average length of ASW exercises (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 scheduled to occur over a short 
duration (1-8 hours); however Mine Countermeasure and Neutralization 
Testing would last 1-10 days (see Tables 3 and 4). The explosive 
component of these activities only lasts for minutes. Although 
explosive exercises 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. All of 
these factors make it unlikely that individuals would be exposed to the 
exercise for extended periods or on consecutive 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 (and 
further corrected to account for mitigation and avoidance). 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. 
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 in 
no more than one day, or that some smaller number were exposed in one 
day but a few of those individuals were exposed multiple days within a 
year and a few were not exposed at all. Where the 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 Navy 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 to each 
species.
    In the ocean, unlike a modeling simulation with static animals, 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, some 
repeated exposures across different activities could occur over the 
year with more resident species. In short, we expect that 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 Navy's 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).
    When calculating the proportion of a population affected by takes 
(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. The SARs, 
where available, provide the official population estimate for a given 
species or stock in U.S. waters in a given year (and are typically 
based solely on the most recent survey data). 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 information used to estimate 
take includes the best available survey abundance data to model density 
layers. Accordingly, in calculating the percentage of takes versus 
abundance for each species in order to assist in understanding both the 
percentage of the species affected, as well as how many days across a 
year individuals could be taken, we use the data most appropriate for 
the situation. For all species and stocks except for a few stocks of 
harbor seals for which SAR data are unavailable and Navy abundance 
surveys of the inland areas of the NWTT Study Area are used, the most 
recent NMFS SARs are used to calculate the proportion of a population 
affected by takes.
    The estimates found in NMFS' SARs remain the official estimates of 
stock abundance where they are current. These estimates are typically 
generated from the most recent shipboard and/or aerial surveys 
conducted. In some cases, NMFS' abundance estimates show substantial 
year-to-year variability. However, for highly migratory species (e.g., 
large whales) or those whose geographic distribution extends well

[[Page 34010]]

beyond the boundaries of the NWTT Study Area (e.g., populations with 
distribution along the entire eastern Pacific Ocean rather than just 
the NWTT Study Area), comparisons to the SAR are appropriate. Many of 
the stocks present in the NWTT Study Area have ranges significantly 
larger than the NWTT Study Area and that abundance is captured by the 
SAR. A good descriptive example is migrating large whales, which 
traverse the NWTT Study Area for several days to weeks on their 
migrations. Therefore, at any one time there may be a stable number of 
animals, but over the course of the entire year the entire population 
may pass through the NWTT Study Area. 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 NWTT Study Area.
Temporary Threshold Shift
    NMFS and the Navy have estimated that all species of marine mammals 
may sustain 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. Tables 52-57 indicate the 
number of takes by TTS that may be incurred by different species from 
exposure to active sonar and explosives. The TTS sustained by an animal 
is primarily classified by three characteristics:
    1. Frequency--Available data (of mid-frequency hearing specialists 
exposed to mid- or high-frequency sounds; Southall et al., 2007) 
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). The Navy's MF sources, which are the highest power and most 
numerous sources and the ones that cause the most take, utilize the 1-
10 kHz frequency band, which suggests that if TTS were to be induced by 
any of these MF sources it would be in a frequency band somewhere 
between approximately 2 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 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 these sources is unlikely. 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 
non-communication 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). This frequency provides 
information about the cues to which a marine mammal may be temporarily 
less sensitive, but not the degree or duration of sensitivity loss. TTS 
from explosives would be broadband.
    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 dB level is higher or 
the duration is longer). The threshold for the onset of TTS was 
discussed previously in this 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) 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. However, since any hull-mounted sonar such as the SQS-53 
(MFAS), emits a ping typically every 50 seconds, incurring those levels 
of TTS is highly unlikely. Since any hull-mounted sonar, such as the 
SQS-53, engaged in anti-submarine warfare training would be moving at 
between 10 and 15 knots and nominally pinging every 50 seconds, the 
vessel will have traveled a minimum distance of approximately 257 m 
during the time between those pings. A scenario could occur where an 
animal does not leave the vicinity of a ship or travels a course 
parallel to the ship, however, the close distances required make TTS 
exposure unlikely. For a Navy vessel moving at a nominal 10 knots, it 
is unlikely a marine mammal could maintain speed parallel to the ship 
and receive adequate energy over successive pings to suffer TTS.
    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 (i.e., single digits of sensitivity loss). 
To add context to this degree of TTS, individual marine mammals may 
regularly experience variations of 6 dB differences in hearing 
sensitivity across time (Finneran et al., 2000, 2002; Schlundt et al., 
2000).
    3. Duration of TTS (recovery time)--In the TTS laboratory studies 
(as 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, almost all individuals 
recovered within 1 day (or less, often in minutes), although in one 
study (Finneran et al., 2007), recovery took 4 days.
    Based on the range of degree and duration of TTS reportedly induced 
by exposures to non-pulse sounds of energy higher than that to which 
free-swimming marine mammals in the field are likely to be exposed 
during LFAS/MFAS/HFAS training and testing exercises in the NWTT Study 
Area, it is unlikely that marine mammals would ever sustain a TTS from 
MFAS that alters their sensitivity by more than 20 dB for more than a 
few hours--and any incident of TTS would likely be far less severe due 
to the short duration of the majority of the events and the speed of a 
typical vessel, especially given the fact that the higher power sources 
resulting in TTS are predominantly intermittent, which have been shown 
to result in shorter durations of TTS. Also, for the same reasons 
discussed in the Preliminary Analysis and Negligible Impact 
Determination--Diel Cycle section, and because of the short distance 
within which animals would need to approach the sound source, it is 
unlikely that animals would be exposed to the levels necessary to 
induce TTS in subsequent time periods such that their recovery is 
impeded. Additionally, though the frequency range of TTS that marine 
mammals might sustain 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

[[Page 34011]]

frequency range of one vocalization type, much less span all types of 
vocalizations or other critical auditory cues.
    Tables 52-57 indicate the number of incidental takes by TTS for 
each species that are likely to result from the Navy's activities. As a 
general point, the majority of these TTS takes are the result of 
exposure to hull-mounted MFAS (MF narrower band sources), 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 (single-
digit), 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 to maybe a few hours at 
most each, a taken individual will have slightly diminished hearing 
sensitivity (slightly 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 is not impactful. In short, the expected 
results of any one of these small 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 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, given the small number of times that any individual might 
incur TTS, the low degree of TTS and the short anticipated duration, 
and the low likelihood that one of these instances would occur in a 
time period in which the specific TTS overlapped the entirety of a 
critical signal, it is unlikely that TTS of the nature expected to 
result from the Navy activities would result in behavioral changes or 
other impacts that would impact any individual's (of any hearing 
sensitivity) reproduction or survival.
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 is occurring. 
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 
species involved in this rule, we do not expect the exposures with the 
potential for masking to be of a long duration. In addition, masking is 
fundamentally more of a concern at lower frequencies, because low 
frequency signals propagate significantly further 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 within which auditory signals can be detected and 
interpreted. 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 Navy occasionally uses LF and more continuous 
sources, it is not in the contemporaneous aggregate amounts that would 
accrue to a masking concern. Specifically, the nature of the activities 
and sound sources used by the Navy do not support the likelihood of a 
level of masking accruing 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. 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 
one 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 one second, 
masking would not occur. Additionally, when the pulses are only several 
microseconds long, the majority of most animals' vocalizations would 
not be masked.
    Most ASW 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 when the source and animal are in 
close proximity. While data are lacking on behavioral responses of 
marine mammals to continuously active sonars, mysticete species are 
known to be able 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, 
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

[[Page 34012]]

ASW activities are geographically dispersed and last for only a few 
hours, often with intermittent sonar use even within this period. Most 
ASW 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 Navy 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 lower 
amounts of operation, are similarly not expected to result in masking. 
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 Navy 
uses would not be expected to result in more than short-term, low 
impact masking that would not affect reproduction or survival.
PTS from Sonar Acoustic Sources and Explosives and Tissue Damage from 
Explosives
    Tables 52 through 57 indicate the number of individuals of each 
species for which Level A harassment in the form of PTS resulting from 
exposure to active sonar and/or explosives is estimated to occur. The 
number of individuals to potentially incur PTS annually (from sonar and 
explosives) for each species/stock ranges from 0 to 180 (the 180 is for 
the Inland Washington stock of harbor porpoise), but is more typically 
0 or 1. No species/stocks have the potential to incur tissue damage 
from sonar or explosives.
    Data suggest that many marine mammals would deliberately avoid 
exposing themselves to the received levels of active sonar necessary to 
induce injury by moving away from or at least modifying their path to 
avoid a close approach. Additionally, in the unlikely event that an 
animal approaches the sonar-emitting vessel at a close distance, NMFS 
has determined that the mitigation measures (i.e., shutdown/powerdown 
zones for active sonar) would typically ensure that animals would not 
be exposed to injurious levels of sound. As discussed previously, the 
Navy utilizes both aerial (when available) and passive acoustic 
monitoring (during ASW exercises, passive acoustic detections are used 
as a cue for Lookouts' visual observations when passive acoustic assets 
are already participating in an activity) in addition to Lookouts on 
vessels to detect marine mammals for mitigation implementation. As 
discussed previously, the Navy utilized a post-modeling quantitative 
assessment to adjust the take estimates based on avoidance and the 
likely success of some portion of the mitigation measures. As is 
typical in predicting biological responses, it is challenging to 
predict exactly how avoidance and mitigation will affect the take of 
marine mammals, and therefore the Navy erred on the side of caution in 
choosing a method that would more likely still overestimate the take by 
PTS to some degree. Nonetheless, these modified Level A harassment take 
numbers represent the maximum number of instances in which marine 
mammals would be reasonably expected to incur PTS, and we have analyzed 
them accordingly.
    If a marine mammal is able to approach a surface vessel within the 
distance necessary to incur PTS in spite of the mitigation measures, 
the likely speed of the vessel (nominally 10-15 kn) 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 PTS. As discussed previously in relation to TTS, the 
likely consequences to the health of an individual that incurs PTS can 
range from mild to more serious dependent upon the degree of PTS and 
the frequency band it is in. The majority of any PTS 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. Regardless of the frequency band, the more 
important point in this case is that any PTS accrued as a result of 
exposure to Navy activities would be expected to be of a small amount 
(single digits). 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 Navy implements 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 to 
improve the sightability of marine mammals and thereby improve 
mitigation effectiveness. Observing for marine mammals during the 
explosive activities would include visual and passive acoustic 
detection methods (when they are available and part of the activity) 
before the activity begins, in order to cover the mitigation zones that 
can range from 600 yds (656 m) to 2,500 yds (2,286 m) depending on the 
source (e.g., explosive sonobuoy, explosive torpedo, explosive bombs; 
see Tables 38-44). For all of these reasons, the proposed mitigation 
measures associated with explosives are expected to be effective in 
preventing tissue damage to any potentially affected species, and no 
species are anticipated to incur tissue damage during the period of the 
proposed rule.
Serious Injury and Mortality
    NMFS is authorizing a very small number of serious injuries or 
mortalities that could occur in the event of a ship strike. We note 
here that the takes from potential ship strikes enumerated below could 
result in non-serious injury, but their worst potential outcome 
(mortality) is analyzed for the purposes of the negligible impact 
determination.
    In addition, we discuss here the connection, and differences, 
between the legal mechanisms for authorizing incidental take under 
section 101(a)(5) for activities such as the Navy's testing and 
training in the NWTT Study Area, and for authorizing incidental take 
from commercial fisheries. In 1988, Congress amended the MMPA's 
provisions for

[[Page 34013]]

addressing incidental take of marine mammals in commercial fishing 
operations. Congress directed NMFS to develop and recommend a new long-
term regime to govern such incidental taking (see MMC, 1994). The need 
to develop a system suited to the unique circumstances of commercial 
fishing operations led NMFS to suggest a new conceptual means and 
associated regulatory framework. That concept, PBR, and a system for 
developing plans containing regulatory and voluntary measures to reduce 
incidental take for fisheries that exceed PBR were incorporated as 
sections 117 and 118 in the 1994 amendments to the MMPA. In 
Conservation Council for Hawaii v. National Marine Fisheries Service, 
97 F. Supp. 3d 1210 (D. Haw. 2015), which concerned a challenge to 
NMFS' regulations and LOAs to the Navy for activities assessed in the 
2013-2018 HSTT MMPA rulemaking, the Court ruled that NMFS' failure to 
consider PBR when evaluating lethal takes in the negligible impact 
analysis under section 101(a)(5)(A) violated the requirement to use the 
best available science.
    PBR is defined in section 3 of the MMPA as ``the maximum number of 
animals, not including natural mortalities, that may be removed from a 
marine mammal stock while allowing that stock to reach or maintain its 
optimum sustainable population'' (OSP) and, although not controlling, 
can be one measure considered among other factors when evaluating the 
effects of M/SI on a marine mammal species or stock during the section 
101(a)(5)(A) process. OSP is defined in section 3 of the MMPA as ``the 
number of animals which will result in the maximum productivity of the 
population or the species, keeping in mind the carrying capacity of the 
habitat and the health of the ecosystem of which they form a 
constituent element.'' Through section 2, an overarching goal of the 
statute is to ensure that each species or stock of marine mammal is 
maintained at or returned to its OSP.
    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. Determination of appropriate values for these three 
elements incorporates significant precaution, such that application of 
the parameter to the management of marine mammal stocks may be 
reasonably certain to achieve the goals of the MMPA. For example, 
calculation of the minimum population estimate (Nmin) 
incorporates the level of precision and degree of variability 
associated with abundance information, while also providing reasonable 
assurance that the stock size is equal to or greater than the estimate 
(Barlow et al., 1995), typically by using the 20th percentile of a log-
normal distribution of the population estimate. In general, the three 
factors are developed on a stock-specific basis in consideration of one 
another in order to produce conservative PBR values that appropriately 
account for both imprecision that may be estimated, as well as 
potential bias stemming from lack of knowledge (Wade, 1998).
    Congress called for PBR to be applied within the management 
framework for commercial fishing incidental take under section 118 of 
the MMPA. As a result, PBR cannot be applied appropriately outside of 
the section 118 regulatory framework without consideration of how it 
applies within the section 118 framework, as well as how the other 
statutory management frameworks in the MMPA differ from the framework 
in section 118. PBR was not designed and is not used as an absolute 
threshold limiting commercial fisheries. Rather, it serves as a means 
to evaluate the relative impacts of those activities on marine mammal 
stocks. Even where commercial fishing is causing M/SI at levels that 
exceed PBR, the fishery is not suspended. When M/SI exceeds PBR in the 
commercial fishing context under section 118, NMFS may develop a take 
reduction plan, usually with the assistance of a take reduction team. 
The take reduction plan will include measures to reduce and/or minimize 
the taking of marine mammals by commercial fisheries to a level below 
the stock's PBR. That is, where the total annual human-caused M/SI 
exceeds PBR, NMFS is not required to halt fishing activities 
contributing to total M/SI but rather utilizes the take reduction 
process to further mitigate the effects of fishery activities via 
additional bycatch reduction measures. In other words, under section 
118 of the MMPA, PBR does not serve as a strict cap on the operation of 
commercial fisheries that may incidentally take marine mammals.
    Similarly, to the extent PBR may be relevant when considering the 
impacts of incidental take from activities other than commercial 
fisheries, using it as the sole reason to deny (or issue) incidental 
take authorization for those activities would be inconsistent with 
Congress's intent under section 101(a)(5), NMFS' long-standing 
regulatory definition of ``negligible impact,'' and the use of PBR 
under section 118. The standard for authorizing incidental take for 
activities other than commercial fisheries under section 101(a)(5) 
continues to be, among other things that are not related to PBR, 
whether the total taking will have a negligible impact on the species 
or stock. Nowhere does section 101(a)(5)(A) reference use of PBR to 
make the negligible impact finding or authorize incidental take through 
multi-year regulations, nor does its companion provision at 
101(a)(5)(D) for authorizing non-lethal incidental take under the same 
negligible-impact standard. NMFS' MMPA implementing regulations state 
that take has a negligible impact when it does not ``adversely affect 
the species or stock through effects on annual rates of recruitment or 
survival''--likewise without reference to PBR. When Congress amended 
the MMPA in 1994 to add section 118 for commercial fishing, it did not 
alter the standards for authorizing non-commercial fishing incidental 
take under section 101(a)(5), implicitly acknowledging that the 
negligible impact standard under section 101(a)(5) is separate from the 
PBR metric under section 118. In fact, in 1994 Congress also amended 
section 101(a)(5)(E) (a separate provision governing commercial fishing 
incidental take for species listed under the ESA) to add compliance 
with the new section 118 but retained the standard of the negligible 
impact finding under section 101(a)(5)(A) (and section 101(a)(5)(D)), 
showing that Congress understood that the determination of negligible 
impact and application of PBR may share certain features but are, in 
fact, different.
    Since the introduction of PBR in 1994, NMFS had used the concept 
almost entirely within the context of implementing sections 117 and 118 
and other commercial fisheries management-related provisions of the 
MMPA. Prior to the Court's ruling in Conservation Council for Hawaii v. 
National Marine Fisheries Service and consideration of PBR in a series 
of section 101(a)(5) rulemakings, there were a few examples where PBR 
had informed agency deliberations under other MMPA sections and 
programs, such as playing a role in the issuance of a few scientific 
research permits and subsistence takings. But as the Court found when 
reviewing examples of past PBR consideration in Georgia Aquarium v. 
Pritzker, 135 F. Supp. 3d 1280 (N.D. Ga. 2015), where NMFS had 
considered PBR outside the commercial fisheries context, ``it has 
treated PBR as only one `quantitative tool' and [has not used it]

[[Page 34014]]

as the sole basis for its impact analyses.'' Further, the agency's 
thoughts regarding the appropriate role of PBR in relation to MMPA 
programs outside the commercial fishing context have evolved since the 
agency's early application of PBR to section 101(a)(5) decisions. 
Specifically, NMFS' denial of a request for incidental take 
authorization for the U.S. Coast Guard in 1996 seemingly was based on 
the potential for lethal take in relation to PBR and did not appear to 
consider other factors that might also have informed the potential for 
ship strike in relation to negligible impact (61 FR 54157; October 17, 
1996).
    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), but nothing in the 
statute requires the application of PBR outside the management of 
commercial fisheries interactions with marine mammals. Nonetheless, 
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 101(a)(5)(A). As noted by NMFS and the U.S. Fish and 
Wildlife Service in our implementation 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.
    When considering PBR during evaluation of effects of M/SI under 
section 101(a)(5)(A), we first calculate a metric for each species or 
stock that incorporates information regarding ongoing anthropogenic M/
SI from all sources into the PBR value (i.e., PBR minus the total 
annual anthropogenic mortality/serious injury estimate in the SAR), 
which is called ``residual PBR.'' (Wood et al., 2012). We first focus 
our analysis on residual PBR because it incorporates anthropogenic 
mortality occurring from other sources. If the ongoing human-caused 
mortality from other sources does not exceed PBR, then residual PBR is 
a positive number, and we consider how the anticipated or potential 
incidental M/SI from the activities being evaluated compares to 
residual PBR using the 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 consider the M/SI from 
the activities being evaluated as described further below.
    When ongoing total anthropogenic mortality from the applicant's 
specified activities does not exceed PBR and residual PBR is a positive 
number, as a simplifying analytical tool we first consider whether the 
specified activities could cause incidental M/SI that is less than 10 
percent of residual PBR (the ``insignificance threshold,'' see below). 
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 (i.e., in the absence of 
any other take) will not adversely affect annual rates of recruitment 
and survival. As such, this amount of M/SI would not be expected to 
affect rates of recruitment or survival in a manner resulting in more 
than a negligible impact on the affected stock unless there are other 
factors that could affect reproduction or survival, such as Level A 
and/or Level B harassment, or other considerations such as information 
that illustrates uncertainty involved in the calculation of PBR for 
some stocks. In a few prior incidental take rulemakings, this threshold 
was identified as the ``significance threshold,'' but it is more 
accurately labeled an insignificance threshold, and so we use that 
terminology here. Assuming that any additional incidental take by Level 
A or Level B harassment from the activities in question would not 
combine with the effects of the authorized M/SI to exceed the 
negligible impact level, the anticipated M/SI caused by the activities 
being evaluated would have a negligible impact on the species or stock. 
However, M/SI above the 10 percent insignificance threshold does not 
indicate that the M/SI associated with the specified activities is 
approaching a level that would necessarily exceed negligible impact. 
Rather, the 10 percent insignificance threshold is meant only to 
identify instances where additional analysis of the anticipated M/SI is 
not required because the negligible impact standard clearly will not be 
exceeded on that basis alone.
    Where the anticipated M/SI is near, at, or above residual PBR, 
consideration of other factors (positive or negative), including those 
outlined above, as well as mitigation is especially important to 
assessing whether the M/SI will have a negligible impact 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. M/SI that exceeds PBR may still potentially be found 
to be negligible in light of other factors that offset concern, 
especially when robust mitigation and adaptive management provisions 
are included.
    In Conservation Council for Hawaii v. National Marine Fisheries 
Service, which involved the challenge to NMFS' issuance of LOAs to the 
Navy in 2013 for activities in the HSTT Study Area, the Court reached a 
different conclusion, stating, ``Because any mortality level that 
exceeds PBR will not allow the stock to reach or maintain its OSP, such 
a mortality level could not be said to have only a `negligible impact' 
on the stock.'' As described above, the Court's statement fundamentally 
misunderstands the two terms and incorrectly indicates that these 
concepts (PBR and ``negligible impact'') are directly connected, when 
in fact nowhere in the MMPA is it indicated that these two terms are 
equivalent.
    Specifically, PBR was designed as a tool for evaluating mortality 
and is defined as the number of animals that

[[Page 34015]]

can be removed while ``allowing that stock to reach or maintain its 
[OSP].'' OSP is defined as a population that falls within a range from 
the population level that is the largest supportable within the 
ecosystem to the population level that results in maximum net 
productivity, and thus is an aspirational management goal of the 
overall statute with no specific timeframe by which it should be met. 
PBR is designed to ensure minimal deviation from this overarching goal, 
with the formula for PBR typically ensuring that growth towards OSP is 
not reduced by more than 10 percent (or equilibrates to OSP 95 percent 
of the time). As PBR is applied by NMFS, it provides that growth toward 
OSP is not reduced by more than 10 percent, which certainly allows a 
stock to ``reach or maintain its [OSP]'' in a conservative and 
precautionary manner--and we can therefore clearly conclude that if PBR 
were not exceeded, there would not be adverse effects on the affected 
species or stocks. Nonetheless, it is equally clear that in some cases 
the time to reach this aspirational OSP level could be slowed by more 
than 10 percent (i.e., total human-caused mortality in excess of PBR 
could be allowed) without adversely affecting a species or stock 
through effects on its rates of recruitment or survival. Thus even in 
situations where the inputs to calculate PBR are thought to accurately 
represent factors such as the species' or stock's abundance or 
productivity rate, it is still possible for incidental take to have a 
negligible impact on the species or stock even where M/SI exceeds 
residual PBR or PBR.
    As noted 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 (such as is 
specifically discussed for the CA/OR/WA stock of humpback whales 
below), 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 the statute is to evaluate the applicant's 
anticipated take in relation to their take's impact on the species or 
stock, not other entities' impacts on the species or stock. Neither the 
MMPA nor NMFS' implementing regulations call for consideration of other 
unrelated activities and their impacts on the species or stock. In 
fact, in response to public comments on the implementing regulations 
NMFS explained that such effects are not considered in making 
negligible impact findings under section 101(a)(5), although the extent 
to which a species or stock is being impacted by other anthropogenic 
activities is not ignored. Such effects are reflected in the baseline 
of existing impacts as reflected in the species' or stock's abundance, 
distribution, reproductive rate, and other biological indicators.
    NMFS guidance for commercial fisheries provides insight when 
evaluating the effects of an applicant's incidental take as compared to 
the incidental take caused by other entities. Parallel to section 
101(a)(5)(A), section 101(a)(5)(E) of the MMPA provides that NMFS shall 
allow the incidental take of ESA-listed endangered or threatened marine 
mammals by commercial fisheries if, among other things, the incidental 
M/SI from the commercial fisheries will have a negligible impact on the 
species or stock. As discussed earlier, the authorization of incidental 
take resulting from commercial fisheries and authorization for 
activities other than commercial fisheries are under two separate 
regulatory frameworks. However, when it amended the statute in 1994 to 
provide a separate incidental take authorization process for commercial 
fisheries, Congress kept the requirement of a negligible impact 
determination for this one category of species, thereby applying the 
standard to both programs. Therefore, while the structure and other 
standards of the two programs differ such that evaluation of negligible 
impact under one program may not be fully applicable to the other 
program (e.g., the regulatory definition of ``negligible impact'' at 50 
CFR 216.103 applies only to activities other than commercial fishing), 
guidance on determining negligible impact for commercial fishing take 
authorizations can be informative when considering incidental take 
outside the commercial fishing context. In 1999, NMFS published 
criteria for making a negligible impact determination pursuant to 
section 101(a)(5)(E) of the MMPA in a notice of proposed permits for 
certain fisheries (64 FR 28800; May 27, 1999). Criterion 2 stated if 
total human-related serious injuries and mortalities are greater than 
PBR, and fisheries-related mortality is less than 0.1 PBR, individual 
fisheries may be permitted if management measures are being taken to 
address non-fisheries-related serious injuries and mortalities. When 
fisheries-related serious injury and mortality is less than 10 percent 
of the total, the appropriate management action is to address 
components that account for the major portion of the total. This 
criterion addresses when total human-caused mortality is exceeding PBR, 
but the activity being assessed is responsible for only a small portion 
of the mortality. The analytical framework we use here appropriately 
incorporates elements of the one developed for use under section 
101(a)(5)(E) and because the negligible impact determination under 
section 101(a)(5)(A) focuses on the activity being evaluated, it is 
appropriate to utilize the parallel concept from the framework for 
section 101(a)(5)(E).
    Accordingly, we are using a similar criterion in our negligible 
impact analysis under section 101(a)(5)(A) to evaluate the relative 
role of an applicant's incidental take when other sources of take are 
causing PBR to be exceeded, but the take of the specified activity is 
comparatively small. Where this occurs, we may find that the impacts of 
the taking from the specified activity may (those impacts alone, before 
we have considered the combined effects from any harassment take) be 
negligible even when total human-caused mortality from all activities 
exceeds PBR if (in the context of a particular species or stock): The 
authorized mortality or serious injury would be less than or equal to 
10 percent of PBR and management measures are being taken to address 
serious injuries and mortalities from the other activities (i.e., other 
than the specified activities covered by the incidental take 
authorization under consideration). We must also determine, though, 
that 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 to result in adverse effects on the 
species or stock through effects on annual rates of recruitment or 
survival.
    As discussed above, however, while PBR is useful in informing the 
evaluation of the effects of M/SI in section 101(a)(5)(A) 
determinations, it is just one consideration to be assessed in 
combination with other factors and is not determinative, including 
because, as explained above, the accuracy and certainty of the data 
used to calculate PBR for the species or stock must be

[[Page 34016]]

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 to exceed PBR (or exceed 10 percent of PBR in the 
case where other human-caused mortality is exceeding PBR but the 
specified activity being evaluated is an incremental contributor, as 
described in the last paragraph) by some small amount and still make a 
negligible impact determination 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. No M/SI are 
anticipated from the Navy's sonar activities or use of explosives. We 
first consider maximum potential incidental M/SI from the Navy's ship 
strike analysis for the affected mysticetes and sperm whales (see Table 
51) 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, we 
begin our evaluation of whether the potential incremental addition of 
M/SI through Navy's ship strikes 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 believes that 
mortal takes of three large whales may occur over the course of the 
seven-year rule. Of the three total M/SI takes, the rule would 
authorize no more than two from any of the following species/stocks 
over the seven-year period: Fin whale (which may come from either the 
Northeast Pacific or CA/OR/WA stock) and humpback whale (which may come 
from either the Central North Pacific or CA/OR/WA stock). Of the three 
total M/SI takes, the rule also would authorize no more than one 
mortality from any of the following species/stocks over the seven-year 
period: Sperm whale (CA/OR/WA stock), minke whale (CA/OR/WA stock), and 
gray whale (Eastern North Pacific stock). We do not anticipate, nor 
authorize, ship strike takes to blue whale (Eastern North Pacific 
stock), minke whale (Alaska stock), or sei whale (Eastern North Pacific 
stock). This means an annual average of 0.14 whales from each species 
or stock where one mortality may occur and an annual average of 0.29 
whales from each species or stock where two mortalities may occur, as 
described in Table 51, is proposed for authorization (i.e., 1 or 2 
takes over 7 years divided by 7 to get the annual number).

                                                    Table 51--Summary Information related to Mortalities Requested for Ship Strike, 2020-2027
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Annual
                                                                    proposed                 Fisheries      Vessel                           Residual
                                                                      NWTT                 interactions   collisions  Annual Navy             PBR-PBR
                                                                   authorized     Total        (Y/N);       (Y/N);        HSTT                 minus                              Recent  UME (Y/
           Species  (stock)             Stock  abundance  (Nbest)    take by   annual  M/   annual rate  annual rate   authorized   PBR *    annual M/      Stock trend \*4\        N);  number
                                                    *                serious    SI * \2\   of M/SI from     of M/SI   take  (2018-            SI and                                 and year
                                                                    injury or                fisheries       from      2023) \5\               HSTT                                (since 2007)
                                                                    mortality              interactions     vessel                          authorized
                                                                       \1\                       *       collision *                          take \3\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale (Northeast Pacific).........  3,168....................        0.29         0.4          N; 0       Y; 0.4            0      5.1         4.7  [uarr]..................               N
Fin whale (CA/OR/WA)..................  9,029....................        0.29      >=43.5      Y; >=0.5        Y; 43          0.4       81        37.1  [uarr]..................               N
Humpback whale (Central North Pacific)  10,103...................        0.29          25        Y; 9.5   \6\ Y; 3.9          0.4       83        57.6  [uarr]..................               N
Humpback whale (CA/OR/WA).............  2,900....................        0.29      >=42.1     Y; >=17.3        Y; 22          0.2     33.4        -8.9  Stable ([uarr]                         N
                                                                                                                                                         (historically).
Sperm whale (CA/OR/WA)................  1,997....................        0.14         0.4        Y; 0.4         N; 0            0      2.5         2.1  Unknown.................               N
Minke whale (CA/OR/WA)................  636......................        0.14       >=1.3      Y; >=1.3         N; 0            0      3.5         2.2  Unknown.................               N
Gray whale (Eastern North Pacific)....  26,960...................        0.14         139        Y; 9.6       Y; 0.8          0.4      801       661.6  [uarr]..................    Y, 264, 2019
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Presented in the 2019 draft SARs or most recent SAR.
\1\ This column represents the annual take by serious injury or mortality by vessel collision and was calculated by the number of mortalities proposed for authorization divided by seven years
  (the length of the rule and LOAs).
\2\ This column represents the total number of incidents of M/SI that could potentially accrue to the specified species or stock. This number comes from the SAR, but deducts the takes accrued
  from either NMFS Science Center research activities or Navy strikes authorized for training and testing activities. No NMFS Science Center or Navy M/SI takes for these stocks are recorded in
  the SARs and no NMFS Science Center M/SI incidental takes have been authorized.
\3\ This value represents the calculated PBR minus the average annual estimate of ongoing anthropogenic mortalities (i.e., total annual human-caused M/SI column and the annual authorized take
  from the HSTT column). This value represents the total PBR for the stock in the stock's entire range.
\4\ See relevant SARs for more information regarding stock status and trends.
\5\ This column represents annual M/SI take authorized through NMFS' current 5-year HSTT regulations/LOAs (83 FR 66846). Note that NMFS has proposed to replace the current HSTT regulations
  with 7-year regulations (84 FR 48388) which propose to authorize the same number of M/SI for the same species/stocks, but over a 7-year period rather than a 5-year period (resulting in
  slightly lower annual authorized take for each species/stock).
\6\ This value represents average annual observed M/SI from ship strikes in Alaska (2.5) and Hawaii (1.4). For the purposes of analysis of potential ship strike (see the Estimated Takes
  section) we incorporated only Alaska ship strikes as only these ship strikes have the potential to overlap with the NWTT Study Area.

Stocks With M/SI Below the Insignificance Threshold

    As noted above, for a species or stock with incidental M/SI less 
than 10 percent of residual PBR, we consider M/SI from the specified 
activities to represent an 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 51, the following species or stocks have 
potential M/SI from ship strike proposed for authorization below their 
insignificance threshold: Fin whale (both the Northeast Pacific and CA/
OR/WA stocks), humpback whale (Central North Pacific stock), sperm 
whale (CA/OR/WA stock), minke whale (CA/OR/WA stock), and gray whale 
(Eastern North Pacific stock). While the M/SI proposed for 
authorization of gray whales (Eastern North Pacific stock) is below the 
insignificance threshold, because of the recent UME, we further address 
how the authorized M/SI and the UME inform the negligible impact 
determination immediately below. For the other five stocks with M/SI 
proposed for authorization 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

[[Page 34017]]

are not discussed further. For the remaining one stock (CA/OR/WA stock 
of humpback whales) with potential M/SI above the insignificance 
threshold, how that M/SI compares to residual PBR, as well as 
additional factors, are discussed below as well.

Gray Whales (Eastern North Pacific Stock)

    For this stock, PBR is currently set at 801. The total annual M/SI 
from other sources of anthropogenic mortality is estimated to be 139. 
In addition, 0.4 annual mortalities have been authorized for this same 
stock in the current incidental take regulations for Navy testing and 
training activities in the HSTT Study Area. This yields a residual PBR 
of 661.6. The additional 0.29 annual mortalities that are proposed for 
authorization in this rule are well below the insignificance threshold 
(10 percent of residual PBR, in this case 66.16). Nonetheless, since 
January 2019, gray whale strandings along the west coast of North 
America have been significantly higher than the previous 18-year 
average. Preliminary findings from necropsies have shown evidence of 
poor to thin body condition. The seasonal pattern of elevated 
strandings in the spring and summer months is similar to that of the 
previous gray whale UME in 1999-2000. Current total monthly strandings 
are slightly higher than 1999 and lower than 2000. If strandings 
continue to follow a similar pattern, we would anticipate a decrease in 
strandings in late summer and fall. However, combined with other annual 
human-caused mortalities, and viewed through the PBR lens (for human-
caused mortalities), total human-caused mortality (inclusive of the 
potential for additional UME deaths) would still fall well below 
residual PBR and the insignificance threshold. Because of the 
abundance, population trend (increasing, despite the UME in 1999-2000), 
and residual PBR (661.6) of this stock, this UME is not expected to 
have impacts on the population rate that, in combination with the 
effects of mortality proposed to be authorized, would affect annual 
rates of recruitment or survival.
Stocks With M/SI Above the Insignificance Threshold

Humpback Whale (CA/OR/WA Stock)

    For this stock, PBR is currently set at 16.7 for U.S. waters and 
33.4 for the stock's entire range. The total annual M/SI is estimated 
at greater than or equal to 42.1. Combined with 0.2 annual mortalities 
that have been authorized for this same stock in the current incidental 
take regulations for Navy testing and training activities in the HSTT 
Study Area, this yields a residual PBR of -8.9. NMFS proposes to 
authorize up to 2 M/SI takes over the seven-year duration of this rule, 
which would be 0.29 M/SI takes annually for the purposes of comparing 
to PBR and considering other possible effects on annual rates of 
recruitment and survival. This means that with the additional 0.29 M/SI 
annual takes proposed in this rule, residual PBR would be exceeded by 
9.19.
    In the commercial fisheries setting for ESA-listed marine mammals 
(which is similar to the non-fisheries incidental take setting, in that 
a negligible impact determination is required that is based on the 
assessment of take caused by the activity being analyzed) NMFS may find 
the impact of the authorized take from a specified activity to be 
negligible even if total human-caused mortality exceeds PBR, 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 under 
consideration). When those considerations are applied in the section 
101(a)(5)(A) context here, the proposed authorized lethal take (0.29 
annually) of humpback whales from the CA/OR/WA stock is significantly 
less than 10 percent of PBR (in fact less than 1 percent of 33.4) and 
there are management measures in place to address M/SI from activities 
other than those the Navy is conducting (as discussed below).
    Based on identical simulations as those conducted to identify 
Recovery Factors for PBR in Wade et al. (1998), but where values less 
than 0.1 were investigated (P. Wade, pers. comm.), we predict that 
where the mortality from a specified activity does not exceed Nmin * 
\1/2\ Rmax * 0.013, the contemplated mortality for the specific 
activity will not delay the time to recovery by more than 1 percent. 
For this stock of humpback whales, Nmin * \1/2\ Rmax * 0.013 = 1.45 and 
the annual mortality proposed for authorization is 0.29 (i.e., less 
than 1.45), which means that the mortality proposed to be authorized in 
this rule for NWTT activities would not delay the time to recovery by 
more than 1 percent.
    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 M/SI to adversely affect the species or stock via 
impacts on annual rates of recruitment or survival, which is discussed 
further below in the species- and stock-specific section.
    In November 2019, NMFS published 2019 draft SARs in which PBR is 
reported as 33.4 with the predicted average annual mortality greater 
than or equal to 42.1 (including 22 estimated from vessel collisions 
and greater than 17.3 observed fisheries interactions). While the 
observed M/SI from vessel strikes remains low at 2.2 per year, the 2018 
final and 2019 draft SARs rely on a new method to estimate annual 
deaths by ship 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 this stock from vessel strikes. The 
authors (Rockwood et al., 2017) do not suggest that ship strikes 
suddenly increased to 22. In fact, the model is not specific to a year, 
but rather offers a generalized prediction of ship strikes 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 ship 
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 CA/OR/WA stock of 
humpback whales is considered stable (or increasing based on population 
trends since 1990) nevertheless.
    The CA/OR/WA stock of humpback whales experienced a steady increase 
from the 1990s through approximately 2008, and more recent estimates 
through 2014 indicate a leveling off of the population size. This stock 
is comprised of the feeding groups of three DPSs. Two DPSs associated 
with this stock are listed under the ESA as either endangered (Central 
America DPS) or threatened (Mexico DPS), while the third (Hawaii DPS) 
is not listed. Humpback whales from the Hawaii DPS are anticipated to 
be rare in the Study Area with a probability of the DPS foraging in the 
waters of the Study Area of 1.6 percent (including summer areas of 
Oregon/California and Southern British Columbia/Washington from Wade, 
2017). Humpback whales from the Mexico DPS and Central America DPS are 
anticipated to be more prevalent in the Study Area with probabilities 
of the DPSs foraging in the waters of the Study Area of 31.7 and 100 
percent, respectively (including summer

[[Page 34018]]

areas of Oregon/California and Southern British Columbia/Washington 
from Wade, 2017).
    As discussed earlier, we also take into consideration management 
measures in place to address M/SI caused by other activities. The 
California swordfish and thresher shark drift gillnet fishery is one of 
the primary causes of M/SI take from fisheries interactions for 
humpback whales on the West Coast. NMFS established the Pacific 
Offshore Cetacean Take Reduction Team in 1996 and prepared an 
associated Plan (POCTRP) to reduce the risk of M/SI via fisheries 
interactions. In 1997, NMFS published final regulations formalizing the 
requirements of the PCTRP, including the use of pingers following 
several specific provisions and the employment of Skipper education 
workshops.
    Commercial fisheries such as crab pot, gillnet, and prawn fisheries 
are also a significant source of mortality and serious injury for 
humpback whales and other large whales and, unfortunately, have 
increased mortalities and serious injuries over recent years (Carretta 
et al., 2019). However, the 2019 draft SAR notes that a recent increase 
in disentanglement efforts has resulted in an increase in the fraction 
of cases that are reported as non-serious injuries as a result of 
successful disentanglement. More importantly, since 2015, NMFS has 
engaged in a multi-stakeholder process in California (including 
California State resource managers, fishermen, non-governmental 
organizations (NGOs), and scientists) to identify and develop solutions 
and make recommendations to regulators and the fishing industry for 
reducing whale entanglements (see http://www.opc.ca.gov/whale-entanglement-working-group/), referred to as the Whale Entanglement 
Working Group. The Whale Entanglement Working Group has made 
significant progress since 2015 and is tackling the problem from 
multiple angles, including:
     Development of Fact Sheets and Best Practices for specific 
Fisheries issues (e.g., California Dungeness Crab Fishing BMPs and the 
2018-2019 Best Fishing Practices Guide);
     2018-2019 Risk Assessment and Mitigation Program (RAMP) to 
support the state of California in working collaboratively with experts 
(fishermen, researchers, NGOs, etc.) to identify and assess elevated 
levels of entanglement risk and determine the need for management 
options to reduce risk of entanglement; and
     Support of pilot studies to test new fisheries 
technologies to reduce take (e.g., Exploring Ropeless Fishing 
Technologies for the California Dungeness Crab Fishery).
    The Working Group meets regularly, posts reports and annual 
recommendations, and makes all of their products and guidance documents 
readily accessible for the public. The March 2019 Working Group Report 
reported on the status of the fishery closure, progress and continued 
development of the RAMP (though there is a separate RAMP report), 
discussed the role of the Working Group (development of a new Charter), 
and indicated next steps.
    Importantly, in early 2019, as a result of a litigation settlement 
agreement, the California Department of Fish and Wildlife (CDFW) closed 
the Dungeness crab fishery three months early for the year, which is 
expected to reduce the number of likely entanglements. The agreement 
also limits the fishery duration over the next couple of years and has 
different triggers to reduce or close it further. Further, pursuant to 
the settlement, CDFW is required to apply for a Section 10 Incidental 
Take Permit under the ESA to address protected species interactions 
with fishing gear and crab fishing gear (pots), and they have agreed to 
prepare a Conservation Plan by May 2020. Any request for such a permit 
must include a Conservation Plan that specifies, among other things, 
what steps the applicant will take to minimize and mitigate the 
impacts, and the funding that will be available to implement such 
steps.
    Regarding measures in place to reduce mortality from other sources, 
the Channel Islands NMS staff coordinates, collects, and monitors whale 
sightings in and around a Whale Advisory Zone and the Channel Islands 
NMS region, which is within the area of highest vessel strike mortality 
(90th percentile) for humpback whales on the U.S. West Coast (Rockwood 
et al., 2017). The seasonally established Whale Advisory 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 June through November are recommended to 
exercise caution and voluntarily reduce speed to 10 kn 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 Navy chartered 
aircraft. Information on seasonal presence, movement, and general 
distribution patterns of large whales is shared with mariners, NMFS' 
Office of Protected Resources, the U.S. Coast Guard, the 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.
    More recently, similar efforts to reduce entanglement risk and 
severity have also been initiated in Oregon and Washington. Both Oregon 
and Washington are developing applications for ESA Incidental Take 
Permits for their commercial crab fisheries. They advocate similar best 
practices for their fishermen as California, and they are taking 
regulatory steps related to gear marking and pot limits.
    In this case, 0.29 M/SI annually means the potential for two 
mortalities in one or two of the seven years and zero mortalities in 
five or six of those seven years. Therefore, the Navy would not be 
contributing to the total human-caused mortality at all in at least 
five of the seven, or 71.4 percent, of the years covered by this rule. 
That means that even if a humpback whale from the CA/OR/WA stock were 
to be struck, in at least five of the seven 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, of an 
effect on population rates than the loss of a reproductive female (as 
males are known to mate with multiple females), 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 strikes proposed to be authorized by this rule would be males, 
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 any M/SI in five or six of the years and due to the fact 
that strikes could be males. 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. Wade et al. (1998), authors of the paper 
from which the current PBR equation is derived, note that ``Estimating 
incidental mortality in one 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.''

[[Page 34019]]

    The information included here illustrates that this humpback whale 
stock is stable, the potential (and proposed authorized) mortality is 
well below 10 percent (0.87 percent) of PBR, and management actions are 
in place to minimize both fisheries interactions and ship strike from 
other vessel activity in one of the highest-risk areas for strikes. 
More specifically, although the total human-mortality exceeds PBR, the 
authorized mortality proposed for the Navy's specified activities would 
incrementally contribute less than 1 percent of that and, further, 
given the fact that it would occur in only one or two of the seven 
years with a 50 percent chance of the take involving males (far less 
impactful to the population), the potential impacts on population rates 
are even less. Based on all of the considerations described above, 
including consideration of the fact that the M/SI of 0.29 proposed for 
authorization would not delay the time to recovery by more than 1 
percent, we do not expect the potential lethal take from Navy 
activities, alone, to adversely affect the CA/OR/WA stock of 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 CA/OR/WA stock of humpback whales from the Navy's 
activities to ensure that the total authorized takes would have a 
negligible impact on the species and 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

    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 seven-year training and testing period are shown in Tables 
32 and 33 along with the discussion in the Estimated Take of Marine 
Mammals section on Vessel Strike. The vast majority of predicted 
exposures (greater than 99 percent) are expected to be Level B 
harassment (non-injurious TTS and behavioral reactions) from acoustic 
and explosive sources during training and testing activities at 
relatively low received levels.
    In the discussions below, the estimated Level B harassment takes 
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. Below, we compare the 
total take numbers (including PTS, TTS, and behavioral disruption) for 
species or stocks to their associated abundance estimates to evaluate 
the magnitude of impacts across the species and to individuals. 
Specifically, when an abundance percentage comparison is below 100, it 
means that that percentage or less of the individuals will be affected 
(i.e., some individuals will not be taken at all), that the average for 
those taken is one day per year, and that we would not expect any 
individuals to be taken more than a few times in a year. When it is 
more than 100 percent, it means there will definitely be some number of 
repeated takes of individuals. For example, if the percentage is 300, 
the average would be each individual is taken on three days in a year 
if all were taken, but it is more likely that some number of 
individuals will be taken more than three times and some number of 
individuals fewer or not at all. While it is not possible to know the 
maximum number of days across which individuals of a stock might be 
taken, in acknowledgement of the fact that it is more than the average, 
for the purposes of this analysis, we assume a number approaching twice 
the average. For example, if the percentage of take compared to the 
abundance is 800, we estimate that some individuals might be taken as 
many as 16 times. Those comparisons are included in the sections below.
    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 a PTS or TTS take may sometimes, for example, 
also be subject to behavioral disturbance at the same time. As 
described above in this section, the degree of PTS, 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 PTS 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 jeopardized, although those sorts of 
impacts are generally not expected to result from these activities. 
Accordingly, in analyzing the number of takes and the likelihood of 
repeated and sequential takes, we consider the total takes, not just 
the Level B harassment takes by behavioral disruption, so that 
individuals potentially exposed to both threshold shift and behavioral 
disruption are appropriately considered. The number of Level A 
harassment takes by PTS are so low (and zero in most 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 marine mammals from 
sonar and other active sound sources during testing and training 
activities would be primarily from ASW events. It is important to note 
that unlike other Navy Training and Testing Study Areas, there are no 
MTEs proposed for the NWTT Study Area. 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.
    Occasional, milder behavioral reactions 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 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., 2018; Harris et al., 
2017; King et al., 2015; NAS 2017; New et al., 2014; Southall et al., 
2007; Villegas-Amtmann et al., 2015). When impacts to individuals 
increase in magnitude or severity such that either

[[Page 34020]]

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 a portion of 
the population (typically approximately 50 percent). 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, as noted previously, 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 
explained earlier, such severe impacts from the Navy's activities would 
be very infrequent and not likely to occur at all for most species and 
stocks. Even for those species or stocks where it is possible for a 
small number of females to experience reproductive effects, we explain 
below why there still would be no effect on rates of recruitment or 
survival.
    The analyses below in some cases address species collectively if 
they occupy the same functional hearing group (i.e., low, mid, and 
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 Navy's 
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 subsection. Specifically 
below, we first give broad descriptions of the mysticete, odontocete, 
and pinniped groups and then differentiate into further groups as 
appropriate.
Mysticetes
    This section builds on the broader discussion above and brings 
together the discussion of the different types and amounts of take that 
different species and stocks could potentially or would likely incur, 
the applicable mitigation, and the status of the species and stocks to 
support the preliminary negligible impact determinations for each 
species or stock. We have described (earlier in this section) the 
unlikelihood of any masking having effects that would impact the 
reproduction or survival of any of the individual marine mammals 
affected by the Navy's activities. We have also described above in the 
Potential Effects of Specified Activities on Marine Mammals and their 
Habitat section the unlikelihood of any habitat impacts having effects 
that would impact the reproduction or survival of any of the individual 
marine mammals affected by the Navy's activities. For mysticetes, there 
is no predicted PTS from sonar or explosives and no predicted tissue 
damage from explosives for any species. Much of the discussion below 
focuses on the behavioral effects and the mitigation measures that 
reduce the probability or severity of effects. Because there are 
species-specific and stock-specific considerations as well as M/SI take 
proposed for several stocks, at the end of the section we break out our 
findings on a species-specific and, for one species, stock-specific 
basis.
    In Table 52 below for mysticetes, we indicate for each species and 
stock the total annual numbers of take by mortality, Level A and Level 
B harassment, and a number indicating the instances of total take as a 
percentage of abundance.

[[Page 34021]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.008

    The majority of takes by harassment of mysticetes in the NWTT Study 
Area are caused by anti-submarine warfare (ASW) activities in the 
Offshore portion of the Study Area. Anti-submarine activities include 
sources from the MFAS bin (which includes hull-mounted sonar) because 
they are high level, narrowband sources in the 1-10 kHz range, which 
intersect what is estimated to be the most sensitive area of hearing 
for mysticetes. They also are used in a large portion of exercises (see 
Tables 3 and 4). Most of the takes (90 percent) from the MF1 bin in the 
NWTT Study Area would result from received levels between 160 and 178 
dB SPL, while another 9 percent would result from exposure between 178 
and 184 dB SPL. For the remaining active sonar bin types, the 
percentages are as follows: LF4 = 97 percent between 124 and 142 dB 
SPL, MF4 = 95 percent between 136 and 148 dB SPL, MF5 = 97 percent 
between 112 and 142 dB SPL, and HF4 = 91 percent between 100 and 154 dB 
SPL. For mysticetes, explosive training activities do not result in any 
take. Explosive testing activities result in a small number of 
behavioral Level B harassment takes (0-6 per stock) and TTS takes (0-2 
per stock). Based on this information, the majority of the Level B 
behavioral harassment is expected to be of low to sometimes moderate 
severity and of a relatively shorter duration. No PTS or tissue damage 
from training and testing activities is anticipated or proposed for 
authorization for any species or stock.
    Research and observations show that if mysticetes are exposed to 
sonar or other active acoustic sources they may react in a number of 
ways depending on the characteristics of the sound source, their 
experience with the sound source, and whether they are migrating or on 
seasonal feeding or breeding grounds. Behavioral reactions may include 
alerting, breaking off feeding dives and surfacing, diving or swimming 
away, or no response at all (DOD, 2017; Nowacek, 2007; Richardson, 
1995; Southall et al., 2007). Overall, mysticetes have been observed to 
be more reactive to acoustic disturbance when a noise source is located 
directly on their migration route. Mysticetes disturbed while migrating 
could pause their migration or route around the disturbance, while 
males en route to breeding grounds have been shown to be less 
responsive to disturbances. Although some may pause temporarily, they 
will resume migration shortly after the exposure ends. Animals 
disturbed while engaged in other activities such as feeding or 
reproductive behaviors may be more likely to ignore or tolerate the 
disturbance and continue their natural behavior patterns. Alternately, 
adult females with calves may be more responsive to stressors. As noted 
in the Potential Effects of Specified Activities on Marine Mammals and 
Their Habitat section, there are multiple examples from behavioral 
response studies of odontocetes ceasing their feeding dives when 
exposed to sonar pulses at certain levels, but alternately, blue whales 
were less likely to show a visible response to sonar exposures at 
certain levels when feeding than when traveling. However, Goldbogen et 
al. (2013) indicated some

[[Page 34022]]

horizontal displacement of deep foraging blue whales in response to 
simulated MFAS. Southall et al. (2019b) observed that after exposure to 
simulated and operational mid-frequency active sonar, more than 50 
percent of blue whales in deep-diving states responded to the sonar, 
while no behavioral response was observed in shallow-feeding blue 
whales. Southall et al. (2019b) noted that the behavioral responses 
they observed were generally brief, of low to moderate severity, and 
highly dependent on exposure context (behavioral state, source-to-whale 
horizontal range, and prey availability). Most Level B behavioral 
harassment of mysticetes is likely to be short-term and of low to 
sometimes moderate severity, with no anticipated effect on reproduction 
or survival.
    Richardson et al. (1995) noted that avoidance (temporary 
displacement of an individual from an area) reactions are the most 
obvious manifestations of disturbance in marine mammals. Avoidance is 
qualitatively different from the startle or flight response, but also 
differs in the magnitude of the response (i.e., directed movement, rate 
of travel, etc.). Oftentimes avoidance is temporary, and animals return 
to the area once the noise has ceased. Some mysticetes may avoid larger 
activities as they move through an area, although the Navy's activities 
do not typically use the same training locations day-after-day during 
multi-day activities, except periodically in instrumented ranges. 
Therefore, displaced animals could return quickly after even a large 
activity is completed. In the ocean, the use of Navy sonar and other 
active acoustic sources is transient and is unlikely to expose the same 
population of animals repeatedly over a short period of time, 
especially given the broader-scale movements of mysticetes.
    The implementation of procedural mitigation and the sightability of 
mysticetes (due to their large size) further reduces the potential for 
a significant behavioral reaction or a threshold shift to occur (i.e., 
shutdowns are expected to be successfully implemented), which is 
reflected in the amount and type of incidental take that is anticipated 
to occur and proposed for authorization.
    As noted previously, when an animal incurs a threshold shift, it 
occurs in the frequency from that of the source up to one octave above. 
This means that the vast majority of threshold shifts caused by Navy 
sonar sources will typically occur in the range of 2-20 kHz (from the 
1-10 kHz MF bin, though in a specific narrow band within this range as 
the sources are narrowband), and if resulting from hull-mounted sonar, 
will be in the range of 3.5-7 kHz. The majority of mysticete 
vocalizations occur in frequencies below 1 kHz, which means that TTS 
incurred by mysticetes will not interfere with conspecific 
communication. Additionally, many of the other critical sounds that 
serve as cues for navigation and prey (e.g., waves, fish, 
invertebrates) occur below a few kHz, which means that detection of 
these signals will not be inhibited by most threshold shift either. 
When we look in ocean areas where the Navy has been intensively 
training and testing with sonar and other active acoustic sources for 
decades, there is no data suggesting any long-term consequences to 
reproduction or survival rates of mysticetes from exposure to sonar and 
other active acoustic sources.
    All the mysticete species discussed in this section would benefit 
from the procedural mitigation measures described earlier in the 
Proposed Mitigation Measures section. Additionally, the Navy would 
limit activities and employ other measures in mitigation areas that 
would avoid or reduce impacts to mysticetes. Where these mitigation 
areas are designed to mitigate impacts to particular species or stocks 
(gray whales and humpback whales), they are discussed in detail below. 
Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect any species or stock through effects on annual rates 
of recruitment or survival for any of the affected mysticete stocks.

Blue Whale (Eastern North Pacific Stock)

    Blue whales are listed as endangered under the ESA throughout their 
range, but there is no ESA designated critical habitat or biologically 
important areas identified for this species in the NWTT Study Area. The 
SAR identifies this stock as ``stable''. We further note that this 
stock was originally listed under the ESA as a result of the impacts 
from commercial whaling, which is no longer affecting the species. Blue 
whales are anticipated to be present in summer and winter months and 
only in the Offshore Area of the Study Area. No mortality from either 
explosives or vessel strike and no Level A harassment is anticipated or 
proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is less than 1 percent. Given the range of 
blue whales, this information indicates that only a very small portion 
of individuals in the stock are likely impacted and repeated exposures 
of individuals are not anticipated. Regarding the severity of those 
individual takes by behavioral Level B harassment, we have explained 
that the duration of any exposure is expected to be between minutes and 
hours (i.e., relatively short) and the received sound levels largely 
below 172 dB with a small portion up to 184 dB (i.e., of a moderate or 
lower level, less likely to evoke a severe response). Regarding the 
severity of TTS takes, we have explained that they are expected to be 
low-level, of short duration, and mostly not in a frequency band that 
would be expected to interfere with blue whale communication or other 
important low-frequency cues and that the associated lost opportunities 
and capabilities are not at a level that would impact reproduction or 
survival.
    Altogether, this population is stable, only a very small portion of 
the stock is anticipated to be impacted, and any individual blue whale 
is likely to be disturbed at a low-moderate level. No mortality and no 
Level A harassment is anticipated or proposed for authorization. The 
low magnitude and severity of harassment effects is not expected to 
result in impacts on the reproduction or survival of any individuals, 
let alone have impacts on annual rates of recruitment or survival. For 
these reasons, we have preliminarily determined, in consideration of 
all of the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on the Eastern North 
Pacific stock of blue whales.

Fin Whale (Northeast Pacific Stock and California/Oregon/Washington 
Stock)

    Fin whales are listed as endangered under the ESA throughout their 
range, but no ESA designated critical habitat or biologically important 
areas are identified for this species in the NWTT Study Area. The SAR 
identifies these stocks as ``increasing.'' NMFS is proposing to 
authorize two mortalities of fin whales over the seven years covered by 
this rule, but because it is not possible to determine from which stock 
these potential takes would occur, that is 0.29 mortality annually for 
each stock. The addition of this 0.29 annual mortality still leaves the 
total annual human-caused mortality well under residual PBR (37.1 for 
the CA/OR/WA stock and 4.7 for the Northeast Pacific stock) and below 
the insignificance threshold for both stocks. No mortality from 
explosives and no Level A

[[Page 34023]]

harassment is anticipated or proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is less than 1 percent for the Northeast 
Pacific stock and 1.5 percent for the CA/OR/WA stock. This information 
indicates that only a very small portion of individuals in each stock 
are likely impacted and repeated exposures of individuals are not 
anticipated. Regarding the severity of those individual Level B 
harassment takes by behavioral disruption, we have explained that the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB with a small portion up to 184 dB (i.e., of a moderate or lower 
level, less likely to evoke a severe response). Regarding the severity 
of TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
fin whale communication or other important low-frequency cues--and the 
associated lost opportunities and capabilities are not at a level that 
would impact reproduction or survival.
    Altogether, these populations are increasing, only a small portion 
of each stock is anticipated to be impacted, and any individual fin 
whale is likely to be disturbed at a low-moderate level. No Level A 
harassment is anticipated or proposed to be authorized. This low 
magnitude and severity of harassment effects is not expected to result 
in impacts on individual reproduction or survival for any individuals, 
nor are these harassment takes combined with the proposed authorized 
mortality expected to adversely affect these stocks through impacts on 
annual rates of recruitment or survival. For these reasons, we have 
preliminarily determined, in consideration of all of the effects of the 
Navy's activities combined, that the proposed authorized take would 
have a negligible impact on both the Northeast Pacific and CA/OR/WA 
stocks of fin whales.

Humpback Whale (Central North Pacific Stock)

    The Central North Pacific stock of humpback whales consists of 
winter/spring humpback whale populations of the Hawaiian Islands which 
migrate primarily to foraging habitat in northern British Columbia/
Southeast Alaska, the Gulf of Alaska, and the Bering Sea/Aleutian 
Islands (Muto et al. 2019). Three Feeding Area biologically important 
areas for humpback whales overlap with the NWTT Study Area: Northern 
Washington Feeding Area for humpback whales (May-November); Stonewall 
and Heceta Bank Feeding Area for humpback whales (May-November); and 
Point St. George Feeding Area for humpback whales (July-November) 
(Calambokidis et al., 2015). The Marine Species Coastal, Olympic Coast 
National Marine Sanctuary, Stonewall and Hecta Bank Humpback Whale, and 
Point St. George Humpback Whale Mitigation Areas overlap with these 
important foraging areas. The mitigation measures implemented in each 
of these areas including no MF1 MFAS use seasonally or limited MFAS use 
year round, no explosive training, etc. (see details for each area in 
the Proposed Mitigation section), would reduce the severity of impacts 
to humpback whales by reducing interference in feeding that could 
result in lost feeding opportunities or necessitate additional energy 
expenditure to find other good opportunities.
    The SAR identifies this stock as ``increasing'' and the associated 
Hawaii DPS is not listed under the ESA. No mortality from explosives 
and no Level A harassment is anticipated or proposed for authorization. 
NMFS proposes to authorize two mortalities of humpback whales over the 
seven years covered by this rule, but because it is not possible to 
determine from which stock these potential takes would occur, that is 
0.29 mortality annually for both this stock and the CA/OR/WA stock 
(discussed separately below). The addition of this 0.29 annual 
mortality still leaves the total annual human-caused mortality well 
under both the insignificance threshold and residual PBR (57.6).
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated instances of take 
compared to the abundance is 1 percent. This information and the 
complicated far-ranging nature of the stock structure indicates that 
only a very small portion of the stock is likely impacted and repeated 
exposures of individuals are not anticipated. Regarding the severity of 
those individual Level B harassment takes by behavioral disruption, we 
have explained that the duration of any exposure is expected to be 
between minutes and hours (i.e., relatively short) and the received 
sound levels largely below 172 dB with a small portion up to 184 dB 
(i.e., of a moderate or lower level, less likely to evoke a severe 
response). Regarding the severity of TTS takes, they are expected to be 
low-level, of short duration, and mostly not in a frequency band that 
would be expected to interfere with humpback whale communication or 
other important low-frequency cues, and that the associated lost 
opportunities and capabilities are not at a level that would impact 
reproduction or survival.
    Altogether, this population is increasing and the associated DPS is 
not listed as endangered or threatened under the ESA. Only a very small 
portion of the stock is anticipated to be impacted and any individual 
humpback whale is likely to be disturbed at a low-moderate level. No 
Level A harassment is anticipated or proposed to be authorized. This 
low magnitude and severity of harassment effects is not expected to 
result in impacts on individual reproduction or survival, nor are these 
harassment takes combined with the proposed authorized mortality 
expected to adversely affect this stock through effects on annual rates 
of recruitment or survival. For these reasons, we have preliminarily 
determined, in consideration of all of the effects of the Navy's 
activities combined, that the proposed authorized take would have a 
negligible impact on the Central North Pacific stock of humpback 
whales.

Humpback Whale (California/Oregon/Washington Stock)

    The CA/OR/WA stock of humpback whales includes individuals from 
three ESA DPSs: Central America (endangered), Mexico (threatened), and 
Hawaii (not listed). There is no ESA-designated critical habitat for 
humpback whales, however NMFS recently proposed to designate critical 
habitat for humpback whales (84 FR 54354; October 9, 2019). Three 
Feeding Area biologically important areas for humpback whales overlap 
with the NWTT Study Area: Northern Washington Feeding Area for humpback 
whales (May-November); Stonewall and Heceta Bank Feeding Area for 
humpback whales (May-November); and Point St. George Feeding Area for 
humpback whales (July-November) (Calambokidis et al., 2015). The Marine 
Species Coastal, Olympic Coast National Marine Sanctuary, Stonewall and 
Hecta Bank Humpback Whale, and Point St. George Humpback Whale 
Mitigation Areas overlap with these important foraging areas. The 
mitigation measures implemented in each of these areas including no MF1 
MFAS use seasonally or limited MFAS use year round, no explosive 
training, etc. (see details for each area in the Proposed Mitigation 
section), would reduce the severity of impacts to humpback whales by 
reducing interference in feeding that could result in lost feeding

[[Page 34024]]

opportunities or necessitate additional energy expenditure to find 
other good opportunities.
    The SAR identifies this stock as stable (having shown a long-term 
increase from 1990 and then leveling off between 2008 and 2014). NMFS 
proposes to authorize two mortalities over the seven years covered by 
this rule, or 0.29 mortality annually. With the addition of this 0.29 
annual mortality, the total annual human-caused mortality exceeds 
residual PBR by 9.19. However, as described in more detail in the 
Serious Injury or Mortality section, when total human-caused mortality 
exceeds PBR, we consider whether the incremental addition of a small 
amount of mortality proposed for authorization from the specified 
activity may still result in a negligible impact, in part by 
identifying whether it is less than 10 percent of PBR. In this case, 
the mortality proposed for authorization is well below 10 percent of 
PBR (less than one percent, in fact) and management measures are in 
place to reduce mortality from other sources. More importantly, as 
described above in the Serious Injury or Mortality section, the 
mortality of 0.29 proposed for authorization would not delay the time 
to recovery by more than 1 percent. Given these considerations, the 
incremental addition of two mortalities over the course of the seven-
year Navy rule is not expected to, alone, lead to adverse impacts on 
the stock through effects on annual rates of recruitment or survival. 
No mortality from explosives and no Level A harassment is anticipated 
or proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is 3 percent. Given the range of humpback 
whales, this information indicates that only a very small portion of 
individuals in the stock are likely impacted and repeated exposures of 
individuals are not anticipated. Regarding the severity of those 
individual Level B harassment takes by behavioral disruption, we have 
explained that the duration of any exposure is expected to be between 
minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a small portion up to 184 dB (i.e., of 
a moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be low-level, 
of short duration, and mostly not in a frequency band that would be 
expected to interfere with humpback whale communication or other 
important low-frequency cues and the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival.
    Altogether, this population is stable (even though two of the three 
associated DPSs are listed as endangered or threatened under the ESA), 
only a small portion of the stock is anticipated to be impacted, and 
any individual humpback whale is likely to be disturbed at a low-
moderate level. No Level A harassment is anticipated or proposed to be 
authorized. This low magnitude and severity of harassment effects is 
not expected to result in impacts on the reproduction or survival of 
any individuals and, therefore, when combined with the proposed 
authorized mortality (which our earlier analysis indicated will not, 
alone, have more than a negligible impact on this stock of humpback 
whales), the total take is not expected to adversely affect this stock 
through impacts on annual rates of recruitment or survival. For these 
reasons, we have preliminarily determined, in consideration of all of 
the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on the CA/OR/WA stock of 
humpback whales.

Minke Whale (Alaska and California/Oregon/Washington Stocks)

    The status of these stocks is unknown and the species is not listed 
under the ESA. No biologically important areas have been identified for 
this species in the NWTT Study Area. NMFS proposes to authorize one 
mortality over the seven years covered by this rule, or 0.14 mortality 
annually. The addition of this 0.14 annual mortality still leaves the 
total annual human-caused mortality well under the residual PBR (2.2) 
and below the insignificance threshold. No mortality from explosives 
and no Level A harassment is anticipated or proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is less than 1 percent for the Alaska stock 
(based on, to be conservative, the smallest available provisional 
estimate in the SAR, which is derived from surveys that cover only a 
portion of the stock's range) and 47.5 percent for the CA/OR/WA stock. 
Given the range of minke whales, this information indicates that only a 
portion of individuals in these stocks are likely to be impacted and 
repeated exposures of individuals are not anticipated. Regarding the 
severity of those individual Level B harassment takes by behavioral 
disruption, we have explained that the duration of any exposure is 
expected to be between minutes and hours (i.e., relatively short) and 
the received sound levels largely below 172 dB with a small portion up 
to 184 dB (i.e., of a moderate or lower level, less likely to evoke a 
severe response). Regarding the severity of TTS takes, they are 
expected to be low-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--and the associated 
lost opportunities and capabilities are not at a level that would 
impact reproduction or survival.
    Altogether, although the status of the stocks is unknown, the 
species is not listed under the ESA as endangered or threatened, only a 
portion of these stocks is anticipated to be impacted, and any 
individual minke whale is likely to be disturbed at a low-moderate 
level. No Level A harassment is anticipated or proposed to be 
authorized. This low magnitude and severity of harassment effects is 
not expected to result in impacts on individual reproduction or 
survival, nor are these harassment takes combined with the proposed 
authorized mortality expected to adversely affect these stocks through 
effects on annual rates of recruitment or survival. For these reasons, 
we have preliminarily determined, in consideration of all of the 
effects of the Navy's activities combined, that the proposed authorized 
take would have a negligible impact on the Alaska and CA/OR/WA stocks 
of minke whales.

Sei Whale (Eastern North Pacific Stock)

    The status of this stock is unknown, however sei whales are listed 
as endangered under the ESA throughout their range. There is no ESA 
designated critical habitat or biologically important areas identified 
for this species in the NWTT Study Area. No mortality from either 
explosives or vessel strikes and no Level A harassment is anticipated 
or proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is 16 percent. This information and the large 
range of sei whales suggests that only a small portion of individuals 
in the stock are likely impacted and repeated exposures of individuals 
are not anticipated. Regarding the severity of those individual Level B 
harassment takes by behavioral disruption, we have explained that the 
duration of any exposure is expected to be between

[[Page 34025]]

minutes and hours (i.e., relatively short) and the received sound 
levels largely below 172 dB with a small portion up to 184 dB (i.e., of 
a moderate or lower level, less likely to evoke a severe response). 
Regarding the severity of TTS takes, they are expected to be low-level, 
of short duration, and mostly not in a frequency band that would be 
expected to interfere with sei whale communication or other important 
low-frequency cues and the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival.
    Altogether, the status of the stock is unknown and the species is 
listed as endangered, but only a small portion of the stock is 
anticipated to be impacted and any individual sei whale is likely to be 
disturbed at a low-moderate level. No mortality and no Level A 
harassment is anticipated or proposed for authorization. This low 
magnitude and severity of harassment effects is not expected to result 
in impacts on individual reproduction or survival, much less annual 
rates of recruitment or survival. For these reasons, we have 
preliminarily determined, in consideration of all of the effects of the 
Navy's activities combined, that the proposed authorized take would 
have a negligible impact on the Eastern North Pacific stock of sei 
whales.

Gray Whale (Eastern North Pacific Stock)

    The SAR identifies this stock as ``increasing'' and the associated 
DPS is not listed under the ESA. The NWTT Study Area overlaps with the 
offshore Northwest Washington and the Northern Puget Sound gray whale 
Feeding biologically important areas, and a portion of the Northwest 
coast of Washington approximately from Pacific Beach (WA) and extending 
north to the Strait of Juan de Fuca overlaps with the gray whale 
Migrations Corridor biologically important area. The Marine Species 
Coastal, Olympic Coast National Marine Sanctuary, Stonewall and Hecta 
Bank Humpback Whale, and Point St. George Humpback Whale, and Northern 
Puget Sound Gray Whale Mitigation Areas overlap with these important 
foraging and migration areas. The mitigation measures implemented in 
each of these areas including no MF1 MFAS use seasonally or limited 
MFAS use year round, no explosive training, etc. (see details for each 
area in the Proposed Mitigation section), would reduce the severity of 
impacts to gray whales by reducing interference in feeding and 
migration that could result in lost feeding opportunities or 
necessitate additional energy expenditure to find other good foraging 
opportunities or move migration routes.
    NMFS proposes to authorize one mortality over the seven years 
covered by this rule, or 0.14 mortality annually. The addition of this 
0.14 annual mortality still leaves the total annual human-caused 
mortality well under both the insignificance threshold and residual PBR 
(661.6). No mortality from explosives and no Level A harassment is 
anticipated or proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is less than 1 percent. This information 
indicates that only a very small portion of individuals in the stock 
are likely to be impacted and repeated exposures of individuals are not 
anticipated. Regarding the severity of those individual Level B 
harassment takes by behavioral disruption, we have explained that the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB with a small portion up to 184 dB (i.e., of a moderate or lower 
level, less likely to evoke a severe response). Regarding the severity 
of TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
gray whale communication or other important low-frequency cues and that 
the associated lost opportunities and capabilities are not at a level 
that would impact reproduction or survival.
    Altogether, while we have considered the impacts of the gray whale 
UME, this population of gray whales is not endangered or threatened 
under the ESA and the stock is increasing. No Level A harassment is 
anticipated or proposed to be authorized. Only a very small portion of 
the stock is anticipated to be impacted by Level B harassment and any 
individual gray whale is likely to be disturbed at a low-moderate 
level. This low magnitude and severity of harassment effects is not 
expected to result in impacts to reproduction or survival for any 
individuals, nor are these harassment takes combined with the proposed 
authorized mortality of one whale over the seven-year period expected 
to adversely affect this stock through impacts on annual rates of 
recruitment or survival. For these reasons, we have preliminarily 
determined, in consideration of all of the effects of the Navy's 
activities combined, that the proposed authorized take would have a 
negligible impact on the Eastern North Pacific stock of gray 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 species and stocks could potentially or would likely incur, 
the applicable mitigation, and the status of the species and stock to 
support the negligible impact determinations for each species or stock. 
We have described (earlier in this section) the unlikelihood of any 
masking having effects that would impact the reproduction or survival 
of any of the individual marine mammals affected by the Navy's 
activities. We have also described above in the Potential Effects of 
Specified Activities on Marine Mammals and their Habitat section the 
unlikelihood of any habitat impacts having effects that would impact 
the reproduction or survival of any of the individual marine mammals 
affected by the Navy's activities. For odontocetes, there is no 
anticipated M/SI or tissue damage from sonar or explosives for any 
species. Here, we include information that applies to all of the 
odontocete species, which are then further divided and discussed in 
more detail in the following subsections: Sperm whales, dwarf sperm 
whales, and pygmy sperm whales; beaked whales; dolphins and small 
whales; and porpoises. These subsections include more specific 
information about the groups, as well as conclusions for each species 
or stock represented.
    The majority of takes by harassment of odontocetes in the NWTT 
Study Area are caused by sources from the MFAS bin (which includes 
hull-mounted sonar) because they are high level, typically narrowband 
sources at a frequency (in the 1-10 kHz range) that overlaps a more 
sensitive portion (though not the most sensitive) of the MF hearing 
range and they are used in a large portion of exercises (see Tables 3 
and 4). For odontocetes other than beaked whales and porpoises (for 
which these percentages are indicated separately in those sections), 
most of the takes (96 percent) from the MF1 bin in the NWTT Study Area 
would result from received levels between 160 and 172 dB SPL. For the 
remaining active sonar bin types, the percentages are as follows: LF4 = 
99 percent between 124 and 154 dB SPL, MF4 = 99 percent between 136 and 
166 dB SPL, MF5 = 98 percent between 112 and 148 dB SPL, and HF4 = 95 
percent between 100 and 160 dB SPL. Based on this information, the 
majority of the takes by Level B behavioral harassment are expected to

[[Page 34026]]

be low to sometimes moderate in nature, but still of a generally 
shorter duration.
    For all odontocetes, takes from explosives (Level B behavioral 
harassment, TTS, or PTS) comprise a very small fraction (and low 
number) of those caused by exposure to active sonar. For the following 
odontocetes, zero takes from explosives are expected to occur: Common 
bottlenose dolphins, killer whales, short-beaked common dolphins, 
short-finned pilot whales, the Alaska stock of Dall's porpoises, 
Southeast Alaska stock of harbor porpoises, sperm whales, Baird's 
beaked whale, Cuvier's beaked whale, and Mesoplodon species. For Level 
B behavioral disruption from explosives, with the exception of 
porpoises, one take is anticipated for the remaining species/stocks. 
For the CA/OR/WA stock of Dall's porpoise and the remaining three 
harbor porpoise stocks 1-91 Level B behavioral takes from explosives 
are anticipated. Similarly the instances of TTS and PTS expected to 
occur from explosives for all remaining species/stocks, with the 
exception of porpoises, are anticipated to be low (1-3 for TTS and 1 
for PTS). Because of the lower TTS and PTS thresholds for HF 
odontocetes, for the CA/OR/WA stock of Dall's porpoise and the 
remaining three harbor porpoise stocks, TTS takes range from 61-214 and 
PTS takes range from 27-86.
    Because the majority of harassment takes of odontocetes result from 
the sources in the MFAS bin, the vast majority of threshold shift would 
occur at a single frequency within the 1-10 kHz range and, therefore, 
the vast majority of threshold shift caused by Navy sonar sources would 
be at a single frequency within the range of 2-20 kHz. The frequency 
range within which any of the anticipated narrowband threshold shift 
would occur would fall directly within the range of most odontocete 
vocalizations (2-20 kHz). For example, the most commonly used hull-
mounted sonar has a frequency around 3.5 kHz, and any associated 
threshold shift would be expected to be at around 7 kHz. However, 
odontocete vocalizations typically span a much wider range than this, 
and alternately, threshold shift from active sonar will often be in a 
narrower band (reflecting the narrower band source that caused it), 
which means that TTS incurred by odontocetes would typically only 
interfere with communication within a portion of their range (if it 
occurred during a time when communication with conspecifics was 
occurring) and, as discussed earlier, it would only be expected to be 
of a short duration and relatively small degree. Odontocete 
echolocation occurs predominantly at frequencies significantly higher 
than 20 kHz, though there may be some small overlap at the lower part 
of their echolocating range for some species, which means that there is 
little likelihood that threshold shift, either temporary or permanent, 
would interfere with feeding behaviors. Many of the other critical 
sounds that serve as cues for navigation and prey (e.g., waves, fish, 
invertebrates) occur below a few kHz, which means that detection of 
these signals will not be inhibited by most threshold shift either. The 
low number of takes by threshold shift that might be incurred by 
individuals exposed to explosives would likely be lower frequency (5 
kHz or less) and spanning a wider frequency range, which could slightly 
lower an individual's sensitivity to navigational or prey cues, or a 
small portion of communication calls, for several minutes to hours (if 
temporary) or permanently. There is no reason to think that any of the 
individual odontocetes taken by TTS would incur these types of takes 
over more than one day, or over a few days at most, and therefore they 
are unlikely to incur impacts on reproduction or survival. PTS takes 
from these sources are very low, and while spanning a wider frequency 
band, are still expected to be of a low degree (i.e., low amount of 
hearing sensitivity loss) and unlikely to affect reproduction or 
survival.
    The range of potential behavioral effects of sound exposure on 
marine mammals generally, and odontocetes specifically, has been 
discussed in detail previously. There are behavioral patterns that 
differentiate the likely impacts on odontocetes as compared to 
mysticetes however. First, odontocetes echolocate to find prey, which 
means that they actively send out sounds to detect their prey. While 
there are many strategies for hunting, one common pattern, especially 
for deeper diving species, is many repeated deep dives within a bout, 
and multiple bouts within a day, to find and catch prey. As discussed 
above, studies demonstrate that odontocetes may cease their foraging 
dives in response to sound exposure. If enough foraging interruptions 
occur over multiple sequential days, and the individual either does not 
take in the necessary food, or must exert significant effort to find 
necessary food elsewhere, energy budget deficits can occur that could 
potentially result in impacts to reproductive success, such as 
increased cow/calf intervals (the time between successive calving). 
Second, while many mysticetes rely on seasonal migratory patterns that 
position them in a geographic location at a specific time of the year 
to take advantage of ephemeral large abundances of prey (i.e., 
invertebrates or small fish, which they eat by the thousands), 
odontocetes forage more homogeneously on one fish or squid at a time. 
Therefore, if odontocetes are interrupted while feeding, it is often 
possible to find more prey relatively nearby.

Sperm Whale, Dwarf Sperm Whale, and Pygmy Sperm Whale

    This section builds on the broader odontocete discussion above and 
brings together the discussion of the different types and amounts of 
take that different species and stocks could potentially or would 
likely incur, the applicable mitigation, and the status of the species 
and stocks to support the preliminary negligible impact determinations 
for each species or stock. For sperm whales, there is no predicted PTS 
from sonar or explosives and no predicted tissue damage from 
explosives. For dwarf sperm whales and pygmy sperm whales (described as 
Kogia species below) no mortality or tissue damage from sonar or 
explosives is anticipated or proposed for authorization and only one 
PTS take is predicted.
    In Table 53 below for sperm whales and Kogia species, we indicate 
the total annual numbers of take by mortality, Level A and Level B 
harassment, and a number indicating the instances of total take as a 
percentage of abundance.

[[Page 34027]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.009

    As discussed above, the majority of Level B harassment behavioral 
takes of odontocetes, and thereby sperm whales and Kogia species, is 
expected to be in the form of low to occasionally moderate severity of 
a generally shorter duration. As mentioned earlier in this section, we 
anticipate more severe effects from takes when animals are exposed to 
higher received levels or for longer durations. Occasional milder Level 
B behavioral harassment, as is expected here, is unlikely to cause 
long-term consequences for either individual animals or populations, 
even if some smaller subset of the takes are in the form of a longer 
(several hours or a day) and more moderate response.
    We note that Kogia species (dwarf and pygmy sperm whales), as HF-
sensitive species, have a lower PTS threshold than all other groups and 
therefore are generally likely to experience larger amounts of TTS and 
PTS, and NMFS accordingly has evaluated and would authorize higher 
numbers. However, Kogia whales are still likely to avoid sound levels 
that would cause higher levels of TTS (greater than 20 dB) or PTS. 
Therefore, even though the number of TTS takes are higher than for 
other odontocetes, for all of the reasons described above, TTS and PTS 
are not expected to impact reproduction or survival of any individual.
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect sperm whales and pygmy and dwarf sperm whales through 
effects on annual rates of recruitment or survival.
Sperm Whale (California/Oregon/Washington Stock)
    The SAR identifies the CA/OR/WA stock of sperm whales as ``stable'' 
and the species is listed as endangered under the ESA. No critical 
habitat has been designated for sperm whales under the ESA and there 
are no biologically important areas for sperm whales in the NWTT Study 
Area. NMFS proposes to authorize one mortality for the CA/OR/WA stock 
of sperm whales over the seven years covered by this rule, or 0.14 
mortality annually. The addition of this 0.14 annual mortality still 
leaves the total human-caused mortality under residual PBR (2.1) and 
below the insignificance threshold. No mortality from explosives and no 
Level A harassment is anticipated or proposed for authorization.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is 42 percent for sperm whales. Given the 
range of this stock (which extends the entire length of the West Coast, 
as well as beyond the U.S. EEZ boundary), this information indicates 
that only a portion of the individuals in the stock are likely to be 
impacted and repeated exposures of individuals are not anticipated. 
Additionally, while interrupted feeding bouts are a known response and 
concern for odontocetes, we also know that there are often viable 
alternative habitat options in the relative vicinity. Regarding the 
severity of those individual Level B harassment takes by behavioral 
disruption, we have explained that the duration of any exposure is 
expected to be between minutes and hours (i.e., relatively short) and 
the received sound levels largely below 172 dB (i.e., of a lower, to 
occasionally moderate, level and less likely to evoke a severe 
response). Regarding the severity of TTS takes, they are expected to be 
low-level, of short duration, and mostly not in a frequency band that 
would be expected to interfere with sperm whale communication or other 
important low-frequency cues, and that the associated lost 
opportunities and capabilities are not at a level that will impact 
reproduction or survival.
    Altogether, this population is stable (even though the species is 
listed under the ESA), only a portion of the stock is anticipated to be 
impacted, and any individual sperm whale is likely to be disturbed at a 
low-moderate level. No Level A harassment is anticipated or proposed to 
be authorized. This low magnitude and severity of harassment effects is 
not expected to result in impacts on individual reproduction or 
survival for any individuals, nor are these harassment takes combined 
with the proposed authorized mortality expected to adversely affect 
this stock through impacts on annual rates of recruitment or survival. 
For these reasons, we have preliminarily determined, in consideration 
of all of the effects of the Navy's activities combined, that the 
proposed authorized take would have a negligible impact on the CA/OR/WA 
stock of sperm whales.
Kogia Species (California/Oregon/Washington Stocks)
    The status of the CA/OR/WA stocks of pygmy and dwarf sperm whales 
(Kogia

[[Page 34028]]

species) is unknown and neither are listed under the ESA. There are no 
biologically important areas for Kogia in the NWTT Study Area. No 
mortality or Level A harassment from tissue damage are anticipated or 
proposed for authorization, and one PTS Level A harassment take is 
expected and proposed for authorization. Due to their pelagic 
distribution, small size, and cryptic behavior, pygmy sperm whales and 
dwarf sperm whales (Kogia species) are rarely sighted during at-sea 
surveys and are difficult to distinguish between when visually observed 
in the field. Many of the relatively few observations of Kogia species 
off the U.S. West Coast were not identified to species. All at-sea 
sightings of Kogia species have been identified as pygmy sperm whales 
or Kogia species generally. Stranded dwarf sperm and pygmy sperm whales 
have been found on the U.S. West Coast, however dwarf sperm whale 
strandings are rare. NMFS SARs suggest that the majority of Kogia 
sighted off the U.S. West Coast were likely pygmy sperm whales. As 
such, the stock estimate in the NMFS SAR for pygmy sperm whales is the 
estimate derived for all Kogia species in the region (Barlow, 2016), 
and no separate abundance estimate can be determined for dwarf sperm 
whales, though some low number likely reside in the U.S. EEZ. Due to 
the lack of an abundance estimate it is not possible to predict the 
amount of Level A and Level B harassment take of dwarf sperm whales and 
therefore take estimates are identified as Kogia whales (including both 
pygmy and dwarf sperm whales). We assume only a small portion of those 
takes are likely to be dwarf sperm whales as the available information 
indicates that the density and abundance in the U.S. EEZ is low.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is 21 percent. Given the range of these 
stocks (which extends the entire length of the West Coast, as well as 
beyond the U.S. EEZ boundary), this information indicates that only a 
portion of the individuals in the stocks are likely to be impacted and 
repeated exposures of individuals are not anticipated. Additionally, 
while interrupted feeding bouts are a known response and concern for 
odontocetes, we also know that there are often viable alternative 
habitat options in the relative vicinity. Regarding the severity of 
those individual Level B harassment takes by behavioral disruption, we 
have explained that the duration of any exposure is expected to be 
between minutes and hours (i.e., relatively short) and the received 
sound levels largely below 172 dB (i.e., of a lower, to occasionally 
moderate, level and less likely to evoke a severe response). Regarding 
the severity of TTS takes, they are expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere with sperm whale communication or other important low-
frequency cues, and that the associated lost opportunities and 
capabilities are not at a level that will impact reproduction or 
survival. For these same reasons (low level and frequency band), while 
a small permanent loss of hearing sensitivity (PTS) may include some 
degree of energetic costs for compensating or may mean some small loss 
of opportunities or detection capabilities, at the expected scale the 
estimated one Level A harassment take by PTS would be unlikely to 
impact behaviors, opportunities, or detection capabilities to a degree 
that would interfere with reproductive success or survival of the 
affected individual. Thus, the one Level A harassment take by PTS for 
these stocks would be unlikely to affect rates of recruitment and 
survival for the stock.
    Altogether, although the status of the stocks is unknown, these 
species are not listed under the ESA as endangered or threatened, only 
a portion of these stocks is anticipated to be impacted, and any 
individual Kogia whale is likely to be disturbed at a low-moderate 
level. This low magnitude and severity of harassment effects is not 
expected to result in impacts on the reproduction or survival of any 
individuals, let alone have impacts on annual rates of recruitment or 
survival. One individual could be taken by PTS annually of likely low 
severity. A small permanent loss of hearing sensitivity (PTS) may 
include some degree of energetic costs for compensating or may mean 
some small loss of opportunities or detection capabilities, but at the 
expected scale the estimated one Level A harassment take by PTS would 
be unlikely to impact behaviors, opportunities, or detection 
capabilities to a degree that would interfere with reproductive success 
or survival of that individual, let alone affect annual rates of 
recruitment or survival. For these reasons, we have preliminarily 
determined, in consideration of all of the effects of the Navy's 
activities combined, that the proposed authorized take would have a 
negligible impact on the CA/OR/WA stocks of Kogia whales.

Beaked Whales

    This section builds on the broader odontocete discussion above and 
brings together the discussion of the different types and amounts of 
take that different beaked whale species and stocks would likely incur, 
the applicable mitigation for stocks, and the status of the species and 
stocks to support the preliminary negligible impact determinations for 
each species or stock. For beaked whales, there is no anticipated Level 
A harassment by PTS or tissue damage from sonar or explosives, and no 
mortality is anticipated or proposed for authorization.
    In Table 54 below for beaked whales, we indicate the total annual 
numbers of take by mortality, Level A and Level B harassment, and a 
number indicating the instances of total take as a percentage of 
abundance.

[[Page 34029]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.010

    This first paragraph provides specific information that is in lieu 
of the parallel information provided for odontocetes as a whole. The 
majority of takes by harassment of beaked whales in the NWTT Study Area 
are caused by sources from the MFAS bin (which includes hull-mounted 
sonar) because they are high level narrowband sources that fall within 
the 1-10 kHz range, which overlap a more sensitive portion (though not 
the most sensitive) of the MF hearing range. Also, of the sources 
expected to result in take, they are used in a large portion of 
exercises (see Tables 3 and 4). Most of the takes (95 percent) from the 
MF1 bin in the NWTT Study Area would result from received levels 
between 142 and 160 dB SPL. For the remaining active sonar bin types, 
the percentages are as follows: LF4 = 99 percent between 118 and 148 dB 
SPL, MF4 = 97 percent between 124 and 148 dB SPL, MF5 = 99 percent 
between 100 and 148 dB SPL, and HF4 = 97 percent between 100 and 154 dB 
SPL. Given the levels they are exposed to and beaked whale sensitivity, 
some responses would be of a lower severity, but many would likely be 
considered moderate, but still of generally short duration.
    Research has shown that beaked whales are especially sensitive to 
the presence of human activity (Pirotta et al., 2012; Tyack et al., 
2011) and therefore have been assigned a lower harassment threshold, 
with lower received levels resulting in a higher percentage of 
individuals being harassed and a more distant distance cutoff (50 km 
for high source level, 25 km for moderate source level).
    Beaked whales have been documented to exhibit avoidance of human 
activity or respond to vessel presence (Pirotta et al., 2012). Beaked 
whales were observed to react negatively to survey vessels or low 
altitude aircraft by quick diving and other avoidance maneuvers, and 
none were observed to approach vessels (Wursig et al., 1998). It has 
been speculated for some time that beaked whales might have unusual 
sensitivities to sonar sound due to their likelihood of stranding in 
conjunction with MFAS use, although few definitive causal relationships 
between MFAS use and strandings have been documented (see Potential 
Effects of Specified Activities on Marine Mammals and their Habitat 
section).
    Research and observations show that if beaked whales are exposed to 
sonar or other active acoustic sources, they may startle, break off 
feeding dives, and avoid the area of the sound source to levels of 157 
dB re: 1 [micro]Pa, or below (McCarthy et al., 2011). Acoustic 
monitoring during actual sonar exercises revealed some beaked whales 
continuing to forage at levels up to 157 dB re: 1 [micro]Pa (Tyack et 
al., 2011). Stimpert et al. (2014) tagged a Baird's beaked whale, which 
was subsequently exposed to simulated MFAS. Changes in the animal's 
dive behavior and locomotion were observed when received level reached 
127 dB re: 1 [mu]Pa. However, Manzano-Roth et al. (2013) found that for 
beaked whale dives that continued to occur during MFAS activity, 
differences from normal dive profiles and click rates were not detected 
with estimated received levels up to 137 dB re: 1 [micro]Pa while the 
animals were at depth during their dives. In research done at the 
Navy's fixed tracking range in the Bahamas, animals were observed to 
leave the immediate area of the anti-submarine warfare training 
exercise (avoiding the sonar acoustic footprint at a distance where the 
received level was ``around 140 dB SPL'', according to Tyack et al. 
(2011)), but return within a few days after the event ended (Claridge 
and Durban, 2009; McCarthy et al., 2011; Moretti et al., 2009, 2010; 
Tyack et al., 2010, 2011). Tyack et al. (2011) report that, in reaction 
to sonar playbacks, most beaked whales stopped echolocating, made long 
slow ascent to the surface, and moved away from the sound. A similar 
behavioral response study conducted in Southern California waters 
during the 2010-2011 field season found that Cuvier's beaked whales 
exposed to MFAS displayed behavior ranging from initial orientation 
changes to avoidance responses characterized by energetic fluking and 
swimming away from the source (DeRuiter et al., 2013b). However, the 
authors did not detect similar responses to incidental exposure to 
distant naval sonar exercises at comparable received levels, indicating 
that context of the exposures (e.g., source proximity, controlled 
source ramp-up) may have been a significant factor. The study itself 
found the results inconclusive and meriting further investigation. 
Cuvier's beaked whale responses suggested particular sensitivity to 
sound exposure consistent

[[Page 34030]]

with results for Blainville's beaked whale.
    Populations of beaked whales and other odontocetes on the Bahamas 
and other Navy fixed ranges that have been operating for decades appear 
to be stable. Behavioral reactions (avoidance of the area of Navy 
activity) seem likely in most cases if beaked whales are exposed to 
anti-submarine sonar within a few tens of kilometers, especially for 
prolonged periods (a few hours or more) since this is one of the most 
sensitive marine mammal groups to anthropogenic sound of any species or 
group studied to date and research indicates beaked whales will leave 
an area where anthropogenic sound is present (De Ruiter et al., 2013; 
Manzano-Roth et al., 2013; Moretti et al., 2014; Tyack et al., 2011). 
Research involving tagged Cuvier's beaked whales in the SOCAL Range 
Complex reported on by Falcone and Schorr (2012, 2014) indicates year-
round prolonged use of the Navy's training and testing area by these 
beaked whales and has documented movements in excess of hundreds of 
kilometers by some of those animals. Given that some of these animals 
may routinely move hundreds of kilometers as part of their normal 
pattern, leaving an area where sonar or other anthropogenic sound is 
present may have little, if any, cost to such an animal. Photo 
identification studies in the SOCAL Range Complex, a Navy range that is 
utilized for training and testing, have identified approximately 100 
Cuvier's beaked whale individuals with 40 percent having been seen in 
one or more prior years, with re-sightings up to seven years apart 
(Falcone and Schorr, 2014). These results indicate long-term residency 
by individuals in an intensively used Navy training and testing area, 
which may also suggest a lack of long-term consequences as a result of 
exposure to Navy training and testing activities. More than eight years 
of passive acoustic monitoring on the Navy's instrumented range west of 
San Clemente Island documented no significant changes in annual and 
monthly beaked whale echolocation clicks, with the exception of 
repeated fall declines likely driven by natural beaked whale life 
history functions (DiMarzio et al., 2018). Finally, results from 
passive acoustic monitoring estimated that regional Cuvier's beaked 
whale densities were higher than indicated by NMFS' broad scale visual 
surveys for the United States West Coast (Hildebrand and McDonald, 
2009).
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect beaked whales through effects on annual rates of 
recruitment or survival.
Baird's and Cuvier's Beaked Whales and Mesoplodon Species (California/
Oregon/Washington Stocks)
    The CA/OR/WA stocks of Baird's beaked whale, Cuvier's beaked whale, 
and Mesoplodon species are not listed as endangered or threatened 
species under the ESA, and have been identified as ``stable,'' 
``decreasing,'' and ``increasing,'' respectively, in the SARs. There 
are no biologically important areas for beaked whales in the NWTT Study 
Area. No mortality or Level A harassment from sonar or explosives is 
expected or proposed for authorization.
    No methods are available to distinguish between the six species of 
Mesoplodon beaked whales from the CA/OR/WA stocks (Blainville's beaked 
whale (M. densirostris), Perrin's beaked whale (M. perrini), Lesser 
beaked whale (M. peruvianus), Stejneger's beaked whale (M. stejnegeri), 
Gingko-toothed beaked whale (M. gingkodens), and Hubbs' beaked whale 
(M. carlhubbsi)) when observed during at-sea surveys (Carretta et al., 
2019). Bycatch and stranding records from the region indicate that 
Hubb's beaked whale is the most commonly encountered (Carretta et al., 
2008, Moore and Barlow, 2013). As indicated in the SAR, no species-
specific abundance estimates are available, the abundance estimate 
includes all CA/OR/WA Mesoplodon species, and the six species are 
managed as one unit. Due to the lack of species-specific abundance 
estimates it is not possible to predict the take of individual species 
and take estimates are identified as Mesoplodon species. Therefore our 
analysis considers these Mesoplodon species together.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance is 36 to 78 percent. This information 
indicates that up to 78 percent of the individuals in these stocks are 
likely to be impacted, depending on the stock, though the more likely 
scenario is that a smaller portion than that would be taken, and a 
subset of them would be taken on a few days, with no indication that 
these days would be sequential. Regarding the severity of those 
individual Level B harassment takes by behavioral disruption, we have 
explained that the duration of any exposure is expected to be between 
minutes and hours (i.e., relatively short) and the received sound 
levels largely below 166 dB, though with beaked whales, which are 
considered somewhat more sensitive, this could mean that some 
individuals will leave preferred habitat for a day (i.e., moderate 
level takes). However, while interrupted feeding bouts are a known 
response and concern for odontocetes, we also know that there are often 
viable alternative habitat options nearby. Regarding the severity of 
TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
beaked whale communication or other important low-frequency cues, and 
that the associated lost opportunities and capabilities are not at a 
level that would impact reproduction or survival. As mentioned earlier 
in the odontocete overview, we anticipate more severe effects from 
takes when animals are exposed to higher received levels or sequential 
days of impacts.
    Altogether, none of these species are listed as threatened or 
endangered under the ESA, only a portion of the stocks are anticipated 
to be impacted, and any individual beaked whale is likely to be 
disturbed at a moderate or sometimes low level. This low magnitude and 
low to moderate severity of harassment effects is not expected to 
result in impacts on individual reproduction or survival, let alone 
annual rates of recruitment or survival. No mortality and no Level A 
harassment is anticipated or proposed for authorization. For these 
reasons, we have preliminarily determined, in consideration of all of 
the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on the CA/OR/WA stocks 
of beaked whales.

Dolphins and Small Whales

    This section builds on the broader odontocete discussion above and 
brings together the discussion of the different types and amounts of 
take that different dolphin and small whale species and stocks would 
likely incur, the applicable mitigation for stocks, and the status of 
the species and stocks to support the preliminary negligible impact 
determinations for each species or stock. For all dolphin and small 
whale stocks discussed here except for the CA/OR/WA stocks of Northern 
right whale dolphin and Pacific white-sided dolphin there is no 
predicted PTS from sonar or explosives, and no mortality or tissue 
damage from sonar or explosives is anticipated or proposed for 
authorization. For the CA/OR/WA stocks of Northern right whale dolphin 
and Pacific white-sided dolphin no mortality or tissue damage from 
sonar or explosives is anticipated or proposed for authorization and 
one Level A

[[Page 34031]]

harassment by PTS from testing activities is predicted for each stock.
    In Table 55 below for dolphins and small whales, we indicate the 
total annual numbers of take by mortality, Level A harassment and Level 
B harassment, and a number indicating the instances of total take as a 
percentage of abundance.
[GRAPHIC] [TIFF OMITTED] TP02JN20.011

    As described above, the large majority of Level B behavioral 
harassment to odontocetes, and thereby dolphins and small whales, from 
hull-mounted sonar (MFAS) in the NWTT Study Area would result from 
received levels between 160 and 172 dB SPL. Therefore, the majority of 
Level B harassment takes are expected to be in the form of low to 
occasionally moderate responses of a generally shorter duration. As 
mentioned earlier in this section, we anticipate more severe effects 
from takes when animals are exposed to higher received levels. 
Occasional milder occurrences of Level B behavioral harassment are 
unlikely to cause long-term consequences for individual animals or 
populations that have any effect on reproduction or survival.
    Research and observations show that if delphinids are exposed to 
sonar or other active acoustic sources they may react in a number of 
ways depending on their experience with the sound source and what 
activity they are engaged in at the time of the acoustic exposure. 
Delphinids may not react at all until the sound source is approaching 
within a few hundred meters to within a few kilometers depending on the 
environmental conditions and species. Some dolphin species (the more 
surface-dwelling taxa--typically those with ``dolphin'' in the common 
name, such as bottlenose dolphins, spotted dolphins, spinner dolphins, 
rough-toothed dolphins, etc., but not Risso's dolphin), especially 
those residing in more industrialized or busy areas, have demonstrated 
more tolerance for disturbance and loud sounds and many

[[Page 34032]]

of these species are known to approach vessels to bow-ride. These 
species are often considered generally less sensitive to disturbance. 
Dolphins and small whales that reside in deeper waters and generally 
have fewer interactions with human activities are more likely to 
demonstrate more typical avoidance reactions and foraging interruptions 
as described above in the odontocete overview.
    Below we compile and summarize the information that supports our 
preliminary determination that the Navy's activities would not 
adversely affect dolphins and small whales through effects on annual 
rates of recruitment or survival.
Killer Whales (Eastern North Pacific Alaskan Resident, West Coast 
Transient, Eastern North Pacific Offshore, and Eastern North Pacific 
Southern Resident Stocks)
    With the exception of the Eastern North Pacific Southern Resident 
stock (Southern Resident killer whale DPS) which is listed as 
endangered under the ESA, killer whale stocks in the NWTT Study Area 
are not listed under the ESA. ESA-designated critical habitat for the 
Southern Resident killer whale DPS overlaps with the NWTT Study area in 
the Strait of Juan de Fuca. No biologically important areas for killer 
whales have been identified in the NWTT Study Area. The Eastern North 
Pacific Southern Resident stock is small (75 individuals) and has been 
decreasing in recent years. The Eastern North Pacific Offshore stock is 
reported as ``stable'', and the other stocks have unknown population 
trends. No mortality or Level A harassment is anticipated or proposed 
for authorization for any of these stocks.
    The proposed Marine Species Coastal, Olympic Coast National Marine 
Sanctuary, Stonewall and Heceta Bank Humpback Whale, Point St. George 
Humpback Whale, and Puget Sound and Strait of Juan de Fuca Mitigation 
Areas overlap with important Eastern North Pacific Southern Resident 
(Southern Resident DPS) killer whale foraging and migration habitat. 
Procedural mitigation along with the mitigation measures implemented in 
each of these areas include no MF1 MFAS use seasonally or limited MFAS 
use year round, no explosive training, etc. (see details for each area 
in the Proposed Mitigation Measures section), would reduce the severity 
of impacts to Eastern North Pacific Southern Resident (Southern 
Resident DPS) killer whales by reducing interference in feeding and 
migration that could result in lost feeding opportunities or 
necessitate additional energy expenditure to find other good foraging 
opportunities or migration routes.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance ranges from 1 percent (Eastern North Pacific 
Alaskan Resident) to 95 percent (West Coast Transient). The number of 
estimated total instances of take compared to the abundance for the 
Eastern North Pacific Southern Resident is 68 percent. This information 
indicates that only a very small portion of the Eastern North Pacific 
Alaskan Resident stock is likely impacted and repeated exposures of 
individuals are not anticipated. This information also indicates that a 
few to up to 95 percent of individuals of the remaining three stocks 
could be impacted, if each were taken only one day per year, though the 
more likely scenario is that a smaller portion than that would be 
taken, and a subset of them would be taken multiple days with no 
indication that these days would be sequential. Regarding the severity 
of those individual Level B harassment takes by behavioral disruption, 
we have explained that the duration of any exposure is expected to be 
between minutes and hours (i.e., relatively short) and the received 
sound levels largely below 172 dB (i.e., of a lower, to occasionally 
moderate, level and less likely to evoke a severe response). Regarding 
the severity of TTS takes, they are expected to be low-level, of short 
duration, and mostly not in a frequency band that would be expected to 
interfere with killer whale communication or other important low-
frequency cues, and that the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival.
    Altogether, with the exception of the Eastern North Pacific 
Southern Resident stock which is listed as endangered under the ESA, 
these killer whale stocks are not listed under the ESA. Only a portion 
of these killer whale stocks is anticipated to be impacted, and any 
individual is likely to be disturbed at a low-moderate level, with the 
taken individuals likely exposed on one day or a few days. Even 
acknowledging the small and declining stock size of the Eastern North 
Pacific Southern Resident stock, this low magnitude and severity of 
harassment effects is unlikely to result in impacts on individual 
reproduction or survival, much less annual rates of recruitment or 
survival of any of the stocks. No mortality or Level A harassment is 
anticipated or proposed for authorization for any of the stocks. For 
these reasons, we have preliminarily determined, in consideration of 
all of the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on these killer whale 
stocks.
    All other dolphin and small whale stocks
    None of these stocks is listed under the ESA and their stock 
statuses are considered ``unknown,'' except for the CA/OR/WA stock of 
short-beaked common dolphin which is described as ``increasing''. No 
biologically important areas for these stocks have been identified in 
the NWTT Study Area. No mortality or serious injury is anticipated or 
proposed for authorization. With the exception of one Level A 
harassment PTS take to the CA/OR/WA stocks of Northern right whale 
dolphin and Pacific white-sided dolphin, no Level A harassment by PTS 
or tissue damage is expected or proposed for authorization for these 
stocks.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance ranges from less than 1 percent (North 
Pacific stock of Pacific white-sided dolphins, CA/OR/WA Offshore stock 
of common bottlenose dolphins, and CA/OR/WA stock of short-beaked 
common dolphin) to 100 percent (CA/OR/WA stock of Risso's dolphins). 
All stocks except for the CA/OR/WA stocks of Risso's dolphin, Pacific 
white-sided dolphin, and Northern right whale dolphin have estimated 
total instances of take compared to the abundances less than or equal 
to 11 percent. This information indicates that only a small portion of 
these stocks is likely impacted and repeated exposures of individuals 
are not anticipated. The CA/OR/WA stocks of Risso's dolphins, Pacific 
white-sided dolphin, and Northern right whale dolphin have estimated 
total instances of take compared to the abundances that range from 78 
to 100 percent. This information indicates that up to 100 percent of 
the individuals of these stocks could be impacted, if each were taken 
only one day per year, though the more likely scenario is that a 
smaller portion than that would be taken, and a subset of them would be 
taken on a few days, with no indication that these days would be 
sequential. Regarding the severity of those individual Level B 
harassment takes by behavioral disruption, we have explained that the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB (i.e., of a

[[Page 34033]]

lower, to occasionally moderate, level and less likely to evoke a 
severe response). However, while interrupted feeding bouts are a known 
response and concern for odontocetes, we also know that there are often 
viable alternative habitat options nearby. Regarding the severity of 
TTS takes, they are expected to be low-level, of short duration, and 
mostly not in a frequency band that would be expected to interfere with 
dolphin and small whale communication or other important low-frequency 
cues, and that the associated lost opportunities and capabilities are 
not at a level that would impact reproduction or survival. For these 
same reasons (low level and frequency band), while a small permanent 
loss of hearing sensitivity (PTS) may include some degree of energetic 
costs for compensating or may mean some small loss of opportunities or 
detection capabilities, at the expected scale the estimated one Level A 
harassment take by PTS for the CA/OR/WA stocks of Northern right whale 
dolphin and Pacific white-sided dolphin would be unlikely to impact 
behaviors, opportunities, or detection capabilities to a degree that 
would interfere with reproductive success or survival of that 
individual. Thus the one Level A harassment take by PTS for these 
stocks would be unlikely to affect rates of recruitment and survival 
for the stock.
    Altogether, though the status of these stocks is largely unknown, 
none of these stocks is listed under the ESA and any individual is 
likely to be disturbed at a low-moderate level, with the taken 
individuals likely exposed on one to a few days. This low magnitude and 
severity of harassment effects is not expected to result in impacts on 
individual reproduction or survival. One individual each from the CA/
OR/WA stocks of Northern right whale dolphin and Pacific white-sided 
dolphin could be taken by PTS annually of likely low severity. A small 
permanent loss of hearing sensitivity (PTS) may include some degree of 
energetic costs for compensating or may mean some small loss of 
opportunities or detection capabilities, but at the expected scale the 
estimated Level A harassment takes by PTS for the CA/OR/WA stocks of 
Northern right whale dolphin and Pacific white-sided dolphin would be 
unlikely to impact behaviors, opportunities, or detection capabilities 
to a degree that would interfere with reproductive success or survival 
of any individuals, let alone annual rates of recruitment or survival. 
No mortality is anticipated or proposed for authorization. For these 
reasons, we have preliminarily determined, in consideration of all of 
the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on these stocks of small 
whales and dolphins.

Porpoises

    This section builds on the broader odontocete discussion above and 
brings together the discussion of the different types and amounts of 
take that different porpoise species or stocks would likely incur, the 
applicable mitigation, and the status of the species and stock to 
support the negligible impact determinations for each species or stock. 
For porpoises, there is no anticipated M/SI or tissue damage from sonar 
or explosives for any species.
    In Table 56 below for porpoises, we indicate the total annual 
numbers of take by mortality, Level A harassment and Level B 
harassment, and a number indicating the instances of total take as a 
percentage of abundance.
[GRAPHIC] [TIFF OMITTED] TP02JN20.012

    The majority of takes by harassment of harbor porpoises in the NWTT 
Study Area are caused by sources from the MFAS bin (which includes 
hull-mounted sonar) because they are high level sources at a frequency 
(1-10 kHz), which overlaps a more sensitive portion (though not the 
most sensitive) of the HF hearing range, and of the sources expected to 
result in take, they are used in a large portion of exercises (see 
Tables 3 and 4). Most of the takes (90

[[Page 34034]]

percent) from the MF1 bin in the NWTT Study Area would result from 
received levels between 148 and 166 dB SPL. For the remaining active 
sonar bin types, the percentages are as follows: LF4 = 99 percent 
between 124 and 142 dB SPL, MF4 = 97 percent between 124 and 148 dB 
SPL, MF5 = 97 percent between 118 and 142 dB SPL, and HF4 = 97 percent 
between 118 and 160 dB SPL. Given the levels they are exposed to and 
harbor porpoise sensitivity, some responses would be of a lower 
severity, but many would likely be considered moderate, but still of 
generally short duration.
    Harbor porpoises have been shown to be particularly sensitive to 
human activity (Tyack et al., 2011; Pirotta et al., 2012). 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, 2007). Harbor porpoises routinely avoid and 
swim away from large motorized vessels (Barlow et al., 1988; Evans et 
al., 1994; Palka and Hammond, 2001; Polacheck and Thorpe, 1990). Harbor 
porpoises may startle and temporarily leave the immediate area of the 
training or testing until after the event ends. Accordingly, harbor 
porpoises have been assigned a lower Level B behavioral harassment 
threshold, i.e., a more distant distance cutoff (40 km for high source 
level, 20 km for moderate source level) and, as a result, the number of 
harbor porpoise taken by Level B behavioral harassment through exposure 
to LFAS/MFAS/HFAS in the NWTT Study Area is generally higher than the 
other species. As mentioned earlier in the odontocete overview, we 
anticipate more severe effects from takes when animals are exposed to 
higher received levels or sequential days of impacts; occasional low to 
moderate behavioral reactions are unlikely to affect reproduction or 
survival. Some takes by Level B behavioral harassment could be in the 
form of a longer (several hours or a day) and more moderate response, 
but unless they are repeated over more than several sequential days, 
impacts to reproduction or survival are not anticipated. Even where 
some smaller number of animals could experience effects on reproduction 
(which could happen to a small number), for the reasons explained below 
this would not affect rates of recruitment or survival, especially 
given the status of the stocks.
    While harbor porpoises have been observed to be especially 
sensitive to human activity, the same types of responses have not been 
observed in Dall's porpoises. Dall's porpoises are typically notably 
longer than, and weigh more than twice as much as, harbor porpoises, 
making them generally less likely to be preyed upon and likely 
differentiating their behavioral repertoire somewhat from harbor 
porpoises. Further, they are typically seen in large groups and feeding 
aggregations, or exhibiting bow-riding behaviors, which is very 
different from the group dynamics observed in the more typically 
solitary, cryptic harbor porpoises, which are not often seen bow-
riding. For these reasons, Dall's porpoises are not treated as an 
especially sensitive species (versus harbor porpoises which have a 
lower behavioral harassment threshold and more distant cutoff) but, 
rather, are analyzed similarly to other odontocetes (with takes from 
the sonar bin in the NWTT Study Area resulting from the same received 
levels reported in the Odontocete section above). Therefore, the 
majority of Level B takes are expected to be in the form of milder 
responses compared to higher level exposures. As mentioned earlier in 
this section, we anticipate more severe effects from takes when animals 
are exposed to higher received levels.
All Porpoise Stocks
    These Dall's and harbor porpoise stocks are not listed under the 
ESA and the status of these stocks is considered ``unknown.'' There are 
no biologically important areas for Dall's and harbor porpoises in the 
NWTT Study Area. However, a known important feeding area for harbor 
porpoises overlaps with the Stonewall and Heceta Bank Humpback Whale 
Mitigation Area. No MF1 MFAS or explosives would be used in this 
mitigation area from May 1--November 30, which would reduce the 
severity of impacts to harbor porpoises by reducing interference in 
feeding that could result in lost feeding opportunities or necessitate 
additional energy expenditure to find other good opportunities. No 
mortality or Level A harassment from tissue damage is expected or 
proposed to be authorized for any of these stocks.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), the number of estimated total instances of take 
compared to the abundance ranges from less than 1 percent for the 
Alaska stock of Dall's porpoises to 265 percent for the Washington 
Inland Waters stock of harbor porpoises. The Alaska stock of Dall's 
porpoises, and Southeast Alaska and Northern California/Southern Oregon 
stocks of harbor porpoises have estimated total instances of take 
compared to the abundances less than or equal to 10 percent. This 
information indicates that only a small portion of these stocks is 
likely impacted and repeated exposures of individuals are not 
anticipated. The CA/OR/WA stock of Dall's porpoises and the Northern 
Washington/Oregon Coast and Washington Inland Waters stocks of harbor 
porpoises have estimated total instances of take compared to the 
abundances that range from 131 to 265 percent. This information 
indicates that all individuals of these stocks could be impacted, if 
each were taken two to three days per year, though the more likely 
scenario is that a smaller portion would be taken, and a subset of 
those would be on more days (maybe 5 or 6), with no indication that 
these days would be sequential. Given this and the larger number of 
total takes (totally and to individuals), it is more likely 
(probabilistically) that some small number of individuals could be 
interrupted during foraging in a manner and amount such that impacts to 
the energy budgets of females (from either losing feeding opportunities 
or expending considerable energy to find alternative feeding options) 
could cause them to forego reproduction for a year. 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. However, foregone reproduction (especially for 
only one year within seven, which is the maximum predicted because the 
small number anticipated in any one year makes the probability that any 
individual will be impacted in this way twice in seven years very low) 
has far less of an impact on population rates than mortality and a 
small number of instances would not be expected to adversely impact 
annual rates of recruitment or survival. All indications are that the 
number of times in which reproduction would be likely to be foregone 
would not affect the stocks' annual rates of recruitment or survival.
    Regarding the severity of those individual Level B harassment takes 
by

[[Page 34035]]

behavioral disruption for harbor porpoises, we have explained that the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
166 dB, which for harbor porpoise (which have a lower behavioral Level 
B harassment threshold) would mostly be considered a moderate level. 
Regarding the severity of those individual Level B harassment takes by 
behavioral disruption for Dall's porpoises, we have explained that the 
duration of any exposure is expected to be between minutes and hours 
(i.e., relatively short) and the received sound levels largely below 
172 dB (i.e., of a lower, to occasionally moderate, level and less 
likely to evoke a severe response). Regarding the severity of TTS 
takes, they are expected to be low-level, of short duration, and mostly 
not in a frequency band that would be expected to interfere with 
communication or other important low-frequency cues. The associated 
lost opportunities and capabilities are not at a level that would 
impact reproduction or survival.
    No Level A harassment by PTS is anticipated or proposed for the 
Southeast Alaska stock of harbor porpoise or the Alaska stock of Dall's 
porpoise. For the remaining porpoise stocks, for the same reasons 
explained above for TTS (low level and the likely frequency band), 
while a small permanent loss of hearing sensitivity may include some 
degree of energetic costs for compensating or may mean some small loss 
of opportunities or detection capabilities, the estimated annual Level 
A harassment takes by PTS for these three stocks of harbor porpoises 
and one stock of Dall's porpoises (86 to 180) would be unlikely to 
impact behaviors, opportunities, or detection capabilities to a degree 
that would interfere with reproductive success or survival for most 
individuals. Because of the higher number of PTS takes, however, we 
acknowledge that a few animals could potentially incur permanent 
hearing loss of a higher degree that could potentially interfere with 
their successful reproduction and growth. Given the large population 
sizes of these stocks, even if these occurred, it would not adversely 
impact rates of recruitment or survival.
    Altogether, the status of the harbor porpoise stocks is unknown, 
however harbor porpoises are not listed as endangered or threatened 
under the ESA. Because harbor porpoises are particularly sensitive, it 
is likely that a fair number of the Level B behavioral responses of 
individuals will be of a moderate nature. Additionally, as noted, some 
portion of the stocks may be taken repeatedly on up to several days 
within a year, however this is not anticipated to affect the stocks' 
annual rates of recruitment or survival. Some individuals (86 to 180) 
from the Northern Oregon/Washington Coast, Northern California/Southern 
Oregon, and Washington Inland Waters stocks of harbor porpoises could 
be taken by PTS annually of likely low severity. A small permanent loss 
of hearing sensitivity (PTS) may include some degree of energetic costs 
for compensating or may mean some small loss of opportunities or 
detection capabilities, but at the expected scale the estimated Level A 
harassment takes by PTS for these stocks would be unlikely to impact 
behaviors, opportunities, or detection capabilities to a degree that 
would interfere with reproductive success or survival of any 
individuals, let alone annual rates of recruitment or survival. No 
mortality is anticipated or proposed for authorization. For these 
reasons, we have preliminarily determined, in consideration of all of 
the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on all four stocks of 
harbor porpoises. Altogether, the status of the Dall's porpoise stocks 
is unknown, however Dall's porpoises are not listed as endangered or 
threatened under the ESA. Any individual Dall's porpoise is likely to 
be disturbed at a low-moderate level, with the taken individuals likely 
exposed on one to a few days. This low magnitude and severity of Level 
B harassment effects is not expected to result in impacts on individual 
reproduction or survival, much less annual rates of recruitment or 
survival. Some individuals (98) from the CA/OR/WA stock of Dall's 
porpoises could be taken by PTS annually of likely low severity. A 
small permanent loss of hearing sensitivity (PTS) may include some 
degree of energetic costs for compensating or may mean some small loss 
of opportunities or detection capabilities, but at the expected scale 
the estimated Level A harassment takes by PTS for this stock would be 
unlikely to impact behaviors, opportunities, or detection capabilities 
to a degree that would interfere with reproductive success or survival 
of any individuals, let alone annual rates of recruitment or survival. 
No mortality is anticipated or proposed for authorization. For these 
reasons, we have preliminarily determined, in consideration of all of 
the effects of the Navy's activities combined, that the proposed 
authorized take would have a negligible impact on these stocks of 
Dall's 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 species and stocks would likely incur, the applicable 
mitigation, and the status of the species and stocks to support the 
negligible impact determinations for each species or stock. We have 
described (earlier in this section) the unlikelihood of any masking 
having effects that would impact the reproduction or survival of any of 
the individual marine mammals affected by the Navy's activities. We 
have also described above in the Potential Effects of Specified 
Activities on Marine Mammals and their Habitat section the unlikelihood 
of any habitat impacts having effects that would impact the 
reproduction or survival of any of the individual marine mammals 
affected by the Navy's activities. For pinnipeds, there is no mortality 
or serious injury and no Level A harassment from tissue damage from 
sonar or explosives anticipated or proposed to be authorized for any 
species. Here, we include information that applies to all of the 
pinniped species.
    In Table 57 below for pinnipeds, we indicate the total annual 
numbers of take by mortality, Level A harassment and Level B 
harassment, and a number indicating the instances of total take as a 
percentage of abundance.

[[Page 34036]]

[GRAPHIC] [TIFF OMITTED] TP02JN20.013

    The majority of takes by harassment of pinnipeds in the NWTT Study 
Area are caused by sources from the MFAS bin (which includes hull-
mounted sonar) because they are high level sources at a frequency (1-10 
kHz) which overlaps the most sensitive portion of the pinniped hearing 
range, and of the sources expected to result in take, they are used in 
a large portion of exercises (see Tables 3 and 4). Most of the takes 
(97 percent) from the MF1 bin in the NWTT Study Area would result from 
received levels between 166 and 178 dB SPL. For the remaining active 
sonar bin types, the percentages are as follows: LF4 = 97 percent 
between 130 and 160 dB SPL, MF4 = 99 percent between 142 and 172 dB 
SPL, MF5 = 97 percent between 130 and 160 dB SPL, and HF4 = 99 percent 
between 100 and 172 dB SPL. Given the levels they are exposed to and 
pinniped sensitivity, most responses would be of a lower severity, with 
only occasional responses likely to be considered moderate, but still 
of generally short duration.
    As mentioned earlier in this section, we anticipate more severe 
effects from takes when animals are exposed to higher received levels. 
Occasional milder takes by Level B behavioral harassment are unlikely 
to cause long-term consequences for individual animals or populations, 
especially when they are not expected to be repeated over sequential 
multiple days. For all pinnipeds, harassment takes from explosives 
(behavioral, TTS, or PTS if present) comprise a very small fraction of 
those caused by exposure to active sonar.
    Because the majority of harassment take of pinnipeds results from 
narrowband sources in the range of 1-10 kHz, the vast majority of 
threshold shift caused by Navy sonar sources will typically occur in 
the range of 2-20 kHz. This frequency range falls within the range of 
pinniped hearing, however, pinniped vocalizations typically span a 
somewhat lower range than this (<0.2 to 10 kHz) and threshold shift 
from active sonar will often be in a narrower band (reflecting the 
narrower band source that caused it), which means that TTS incurred by 
pinnipeds would typically only interfere with communication within a 
portion of a pinniped's range (if it occurred during a time when

[[Page 34037]]

communication with conspecifics was occurring). As discussed earlier, 
it would only be expected to be of a short duration and relatively 
small degree. Many of the other critical sounds that serve as cues for 
navigation and prey (e.g., waves, fish, invertebrates) occur below a 
few kHz, which means that detection of these signals will not be 
inhibited by most threshold shifts either. The very low number of takes 
by threshold shifts that might be incurred by individuals exposed to 
explosives would likely be lower frequency (5 kHz or less) and spanning 
a wider frequency range, which could slightly lower an individual's 
sensitivity to navigational or prey cues, or a small portion of 
communication calls, for several minutes to hours (if temporary) or 
permanently.
    Regarding behavioral disturbance, research and observations show 
that pinnipeds in the water may be tolerant of anthropogenic noise and 
activity (a review of behavioral reactions by pinnipeds to impulsive 
and non-impulsive noise can be found in Richardson et al. (1995) and 
Southall et al. (2007)). Available data, though limited, suggest that 
exposures between approximately 90 and 140 dB SPL do not appear to 
induce strong behavioral responses in pinnipeds exposed to non-pulse 
sounds in water (Costa et al., 2003; Jacobs and Terhune, 2002; 
Kastelein et al., 2006c). Based on the limited data on pinnipeds in the 
water exposed to multiple pulses (small explosives, impact pile 
driving, and seismic sources), exposures in the approximately 150 to 
180 dB SPL range generally have limited potential to induce avoidance 
behavior in pinnipeds (Blackwell et al., 2004; Harris et al., 2001; 
Miller et al., 2004). If pinnipeds are exposed to sonar or other active 
acoustic sources they may react in a number of ways depending on their 
experience with the sound source and what activity they are engaged in 
at the time of the acoustic exposure. Pinnipeds may not react at all 
until the sound source is approaching within a few hundred meters and 
then may alert, ignore the stimulus, change their behaviors, or avoid 
the immediate area by swimming away or diving. Effects on pinnipeds 
that are taken by Level B harassment in the NWTT Study Area, on the 
basis of reports in the literature as well as Navy monitoring from past 
activities, will likely be limited to reactions such as increased 
swimming speeds, increased surfacing time, or decreased foraging (if 
such activity were occurring). Most likely, individuals will simply 
move away from the sound source and be temporarily displaced from those 
areas, or not respond at all, which would have no effect on 
reproduction or survival. In areas of repeated and frequent acoustic 
disturbance, some animals may habituate or learn to tolerate the new 
baseline or fluctuations in noise level. Habituation can occur when an 
animal's response to a stimulus wanes with repeated exposure, usually 
in the absence of unpleasant associated events (Wartzok et al., 2003). 
While some animals may not return to an area, or may begin using an 
area differently due to training and testing activities, most animals 
are expected to return to their usual locations and behavior. Given 
their documented tolerance of anthropogenic sound (Richardson et al., 
1995 and Southall et al., 2007), repeated exposures of individuals of 
any of these species to levels of sound that may cause Level B 
harassment are unlikely to result in hearing impairment or to 
significantly disrupt foraging behavior. Thus, even repeated Level B 
harassment of some small subset of individuals of an overall stock is 
unlikely to result in any significant realized decrease in fitness to 
those individuals that would result in any adverse impact on rates of 
recruitment or survival for the stock as a whole.
    Of these stocks, only Guadalupe fur seals are listed as threatened 
under the ESA and the SAR indicates the stock is ``increasing.'' No 
critical habitat under the ESA is designated for the Guadalupe fur 
seal. The other stocks are not ESA-listed. Biologically important areas 
have not been identified for pinnipeds. There are active UMEs for 
Guadalupe fur seals and California sea lions. Since 2015 there have 
been 400 strandings of Guadalupe fur seals (including live and dead 
seals). The California sea lion UME is anticipated to be closed soon as 
elevated strandings occurred from 2013-2016. All of the other pinniped 
stocks are considered ``increasing,'' ``stable,'' or ``unknown'' except 
for Northern fur seals (Eastern Pacific stock), which is considered 
``declining''. No mortality or Level A harassment from tissue damage is 
anticipated or proposed for authorization. All the pinniped species 
discussed in this section would benefit from the procedural mitigation 
measures described earlier in the Proposed Mitigation Measures section.
    Regarding the magnitude of Level B harassment takes (TTS and 
behavioral disruption), for Guadalupe fur seals, the estimated 
instances of takes as compared to the stock abundance is 4 percent. 
This information indicates that only a small portion of individuals in 
the stock are likely impacted and repeated exposures of individuals are 
not anticipated. With the exception of the Hood Canal and Southern 
Puget Sound stocks of harbor seals, for the remaining stocks the number 
of estimated total instances of take compared to the abundance is 2-15 
percent. Given the ranges of these stocks (i.e., large ranges, but with 
individuals often staying in the vicinity of haulouts), this 
information indicates that a small portion of individuals in the stock 
are likely impacted and repeated exposures of individuals are not 
anticipated. For the Southern Puget Sound stock of harbor seals, the 
number of estimated total instances of take compared to the abundance 
is 168 percent. This information indicates that all individuals in this 
stock could be impacted, if each were taken up to 1-2 days per year, 
though the more likely scenario is that a smaller portion than that 
would be taken, and a subset of them would be taken on 3 or 4 days, 
with no indication that these days would be sequential.
    For the Hood Canal stock of harbor seals, the number of estimated 
total instances of take compared to the abundance is 3,084 percent. 
This information indicates that all individuals of this stock could be 
impacted, if each were taken up to 31 days per year, though the more 
likely scenario is that a subset of them would be taken on fewer than 
31 days and a subset would be taken on more than 31 days, and for those 
taken on a higher number of days, some of those days may be sequential. 
Though the majority of impacts are expected to be of a lower to 
sometimes moderate severity, the repeated takes over a potentially fair 
number of sequential days for some individuals in the Hood Canal stock 
of harbor seals makes it more likely that some number of individuals 
could be interrupted during foraging in a manner and amount such that 
impacts to the energy budgets of females (from either losing feeding 
opportunities or expending considerable energy to find alternative 
feeding options) could cause them to forego reproduction for a year 
(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). As noted previously, 
however, foregone reproduction (especially for only one year within 
seven, which is the maximum predicted because the small number 
anticipated in any one year makes the probability that

[[Page 34038]]

any individual will be impacted in this way twice in seven years very 
low) has far less of an impact on population rates than mortality and a 
relatively small number of instances of foregone reproduction would not 
be expected to adversely affect the stock through effects on annual 
rates of recruitment or survival. Regarding the severity of those 
individual takes by Level B behavioral harassment for all pinniped 
stocks, we have explained that the duration of any exposure is expected 
to be between minutes and hours (i.e., relatively short) and the 
received sound levels largely below 178 dB, which is considered a 
relatively low to occasionally moderate level for pinnipeds. However, 
as noted, for the Hood Canal stock, some of these takes could occur on 
some number of sequential days.
    Regarding the severity of TTS takes, they are expected to be low-
level, of short duration, and mostly not in a frequency band that would 
be expected to interfere with pinniped communication or other important 
low-frequency cues, and that the associated lost opportunities and 
capabilities are not at a level that would impact reproduction or 
survival. For these same reasons (low level and frequency band), while 
a small permanent loss of hearing sensitivity may include some degree 
of energetic costs for compensating or may mean some small loss of 
opportunities or detection capabilities, the 1-5 estimated Level A 
harassment takes by PTS for California sea lions, Northern elephant 
seals, and the Washington Northern inland waters, Hood Canal, OR/WA 
Coast, and Southern Puget Sound stocks of harbor seals would be 
unlikely to impact behaviors, opportunities, or detection capabilities 
to a degree that would interfere with reproductive success or survival 
of any individuals.
    Altogether, all pinniped stocks are considered ``increasing,'' 
``stable,'' or ``unknown'' except for Northern fur seals (Eastern 
Pacific stock), which is considered ``declining'' but is not listed 
under the ESA. Only the Guadalupe fur seal is listed under the ESA, 
with a population that is considered increasing. No mortality for 
pinnipeds is anticipated or proposed for authorization. For nearly all 
pinniped stocks (with the exception of the Hood Canal harbor seals) 
only a portion of the stocks are anticipated to be impacted and any 
individual is likely to be disturbed at a low-moderate level. Even 
considering the effects of the UMEs on the Guadalupe fur seal and 
California sea lion stocks, this low magnitude and severity of 
harassment effects is not expected to result in impacts on individual 
reproduction or survival, much less annual rates of recruitment or 
survival. For the Hood Canal stock of harbor seals, a fair portion of 
individuals will be taken by Level B harassment (at a moderate or 
sometimes low level) over a comparatively higher number of days within 
a year, and some smaller portion of those individuals may be taken on 
sequential days, however this is not expected to adversely affect the 
stock through effects on annual rates of recruitment or survival. 
Accordingly, we do not anticipate the relatively small number of 
individual harbor seals that might be taken over repeated days within 
the year in a manner that results in one year of foregone reproduction 
to adversely affect the stock through effects on rates of recruitment 
or survival, given the status of the stock. For these reasons, in 
consideration of all of the effects of the Navy's activities combined, 
we have preliminarily determined that the proposed authorized take 
would have a negligible impact on all stocks of pinnipeds.

Preliminary Determination

    Based on the analysis contained herein of the likely effects of the 
specified activity 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 Activities 
will have a negligible impact on all affected marine mammal species or 
stocks.

Subsistence Harvest of Marine Mammals

    In order to issue an incidental take authorization, NMFS must find 
that the specified activity will not have an ``unmitigable adverse 
impact'' on the subsistence uses of the affected marine mammal species 
or stocks by Alaskan Natives. NMFS has defined ``unmitigable adverse 
impact'' in 50 CFR 216.103 as an impact resulting from the specified 
activity: (1) That is likely to reduce the availability of the species 
to a level insufficient for a harvest to meet subsistence needs by: (i) 
Causing the marine mammals to abandon or avoid hunting areas; (ii) 
Directly displacing subsistence users; or (iii) Placing physical 
barriers between the marine mammals and the subsistence hunters; and 
(2) That cannot be sufficiently mitigated by other measures to increase 
the availability of marine mammals to allow subsistence needs to be 
met.
    To our knowledge there are no relevant subsistence uses of the 
affected marine mammal stocks or species implicated by this action. 
Therefore, NMFS has preliminarily determined that the total taking of 
affected species or stocks would not have an unmitigable adverse impact 
on the availability of the species or stocks for taking for subsistence 
purposes. However, we have limited information on marine mammal 
subsistence use in the Western Behm Canal area of southeastern Alaska 
and seek additional information pertinent to making the final 
determination.

Classification

Endangered Species Act

    There are seven marine mammal species under NMFS jurisdiction that 
are listed as endangered or threatened under the ESA with confirmed or 
possible occurrence in the NWTT Study Area: Blue whale, fin whale, 
humpback whale (Mexico and Central America DPSs), sei whale, sperm 
whale, killer whale (Southern Resident killer whale DPS), and Guadalupe 
fur seal. The Southern Resident killer whale has critical habitat 
designated under the ESA in the NWTT Study Area. NMFS has recently 
published two proposed rules, proposing new or revised ESA-designated 
critical habitat for humpback whales (84 FR 54354; October 9, 2019) and 
Southern Resident killer whales (84 FR 49214; September 19, 2019).
    The Navy will consult with NMFS pursuant to section 7 of the ESA 
for NWTT Study Area activities. NMFS will also consult internally on 
the issuance of the regulations and LOAs under section 101(a)(5)(A) of 
the MMPA.

National Marine Sanctuaries Act

    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 evaluate our proposed actions and alternatives with respect 
to potential impacts on the human environment. Accordingly, NMFS plans 
to adopt the NWTT SEIS/OEIS for the NWTT 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

[[Page 34039]]

MMPA. NMFS is a cooperating agency on the 2019 NWTT DSEIS/OEIS and has 
worked extensively with the Navy in developing the document. The 2019 
NWTT DSEIS/OEIS was made available for public comment at https://www.nwtteis.com in April, 2019. 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.

Regulatory Flexibility Act

    The Office of Management and Budget has determined that this 
proposed rule is not significant for purposes of Executive Order 12866.
    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. The 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 Navy is the sole entity 
that would be affected by this rulemaking, and the Navy is 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 Navy. 
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 the 
Navy and not a small entity, NMFS concludes that the action would not 
result in a significant economic impact on a substantial number of 
small entities.

List of Subjects in 50 CFR Part 218

    Exports, Fish, Imports, Incidental take, Indians, Labeling, Marine 
mammals, Navy, Penalties, Reporting and recordkeeping requirements, 
Seafood, Sonar, Transportation.

    Dated: April 17, 2020.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs,National Marine 
Fisheries Service.

    For reasons set forth in the preamble, 50 CFR part 218 is proposed 
to be amended 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., unless otherwise noted.

0
2. Revise subpart O to read as follows:
Subpart O--Taking and Importing Marine Mammals; U.S. Navy's Northwest 
Training and Testing (NWTT)
Sec.
218.140 Specified activity and geographical region.
218.141 Effective dates.
218.142 Permissible methods of taking.
218.143 Prohibitions.
218.144 Mitigation requirements.
218.145 Requirements for monitoring and reporting.
218.146 Letters of Authorization.
218.147 Renewals and modifications of Letters of Authorization.
218.148 [Reserved]

Subpart O--Taking and Importing Marine Mammals; U.S. Navy's 
Northwest Training and Testing (NWTT)


Sec.  218.140  Specified activity and geographical region.

    (a) Regulations in this subpart apply only to the U.S. Navy (Navy) 
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.
    (b) The taking of marine mammals by the Navy is only authorized if 
it occurs within the NWTT Study Area, which is composed of established 
maritime operating and warning areas in the eastern North Pacific Ocean 
region, including areas of the Strait of Juan de Fuca, Puget Sound, and 
Western Behm Canal in southeastern Alaska. The Study Area includes air 
and water space within and outside Washington state waters, and outside 
state waters of Oregon and Northern California. The eastern boundary of 
the Offshore Area portion of the Study Area is 12 nautical miles (nmi) 
off the coastline for most of the Study Area, including southern 
Washington, Oregon, and Northern California. The Offshore Area includes 
the ocean all the way to the coastline only along that part of the 
Washington coast that lies beneath the airspace of W-237 and the 
Olympic Military Operating Area (MOA) and the Washington coastline 
north of the Olympic MOA. The Study Area includes four existing range 
complexes and facilities: The Northwest Training Range Complex (NWTRC), 
the Keyport Range Complex, the Carr Inlet Operations Area, and the 
Southeast Alaska Acoustic Measurement Facility (SEAFAC). In addition to 
these range complexes, the Study Area also includes Navy pierside 
locations where sonar maintenance and testing occurs as part of 
overhaul, modernization, maintenance, and repair activities at Naval 
Base Kitsap, Bremerton; Naval Base Kitsap, Bangor; and Naval Station 
Everett.
    (c) The taking of marine mammals by the Navy is only authorized if 
it occurs incidental to the Navy conducting training and testing 
activities, including:
    (1) Anti-submarine warfare;
    (2) Expeditionary warfare;
    (3) Mine warfare;
    (4) Surface warfare; and
    (5) Other training and testing activities.


Sec.  218.141  Effective dates.

    Regulations in this subpart are effective from November 9, 2020 
through November 8, 2027.


Sec.  218.142  Permissible methods of taking.

    (a) Under Letters of Authorization (LOAs) issued pursuant to 
Sec. Sec.  216.106 of this chapter and 218.146, the Holder of the LOAs 
(hereinafter ``Navy'') may incidentally, but not intentionally, take 
marine mammals within the area described in Sec.  218.140(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, 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.  218.140(c) is limited to the following species:

[[Page 34040]]



                        Table 1 to Sec.   218.142
------------------------------------------------------------------------
                Species                               Stock
------------------------------------------------------------------------
Blue whale.............................  Eastern North Pacific.
Fin whale..............................  Northeast Pacific.
Fin whale..............................  California/Oregon/Washington.
Sei whale..............................  Eastern North Pacific.
Minke whale............................  Alaska.
Minke whale............................  California/Oregon/Washington.
Humpback whale.........................  Central North Pacific.
Humpback whale.........................  California/Oregon/Washington.
Gray whale.............................  Eastern North Pacific.
Bottlenose dolphin.....................  California/Oregon/Washington
                                          Offshore.
Killer whale...........................  Alaska Resident.
Killer whale...........................  Eastern North Pacific Offshore.
Killer whale...........................  West Coast Transient.
Killer whale...........................  Southern Resident.
Northern right whale dolphin...........  California/Oregon/Washington.
Pacific white-sided dolphin............  North Pacific.
Pacific white-sided dolphin............  California/Oregon/Washington.
Risso's dolphin........................  California/Oregon/Washington.
Short-beaked common dolphin............  California/Oregon/Washington.
Short-finned pilot whale...............  California/Oregon/Washington.
Striped dolphin........................  California/Oregon/Washington.
Pygmy sperm whale......................  California/Oregon/Washington.
Dwarf sperm whale......................  California/Oregon/Washington.
Dall's porpoise........................  Alaska.
Dall's porpoise........................  California/Oregon/Washington.
Harbor porpoise........................  Southeast Alaska.
Harbor porpoise........................  Northern Oregon & Washington
                                          Coast.
Harbor porpoise........................  Northern California/Southern
                                          Oregon.
Harbor porpoise........................  Washington Inland Waters.
Sperm whale............................  California/Oregon/Washington.
Baird's beaked whale...................  California/Oregon/Washington.
Cuvier's beaked whale..................  California/Oregon/Washington.
Mesoplodon species.....................  California/Oregon/Washington.
California sea lion....................  U.S. Stock.
Steller sea lion.......................  Eastern U.S.
Guadalupe fur seal.....................  Mexico.
Northern fur seal......................  Eastern Pacific.
Northern fur seal......................  California.
Harbor seal............................  Southeast Alaska--Clarence
                                          Strait.
Harbor seal............................  Oregon & Washington Coastal.
Harbor seal............................  Washington Northern Inland
                                          Waters.
Harbor seal............................  Hood Canal.
Harbor seal............................  Southern Puget Sound.
Northern elephant seal.................  California.
------------------------------------------------------------------------

Sec.  218.143  Prohibitions.

    Notwithstanding incidental takings contemplated in Sec.  218.142(a) 
and authorized by LOAs issued under Sec. Sec.  216.106 of this chapter 
and 218.146, no person in connection with the activities listed in 
Sec.  218.140(c) may:
    (a) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or an LOA issued under Sec. Sec.  216.106 
of this chapter and 218.146;
    (b) Take any marine mammal not specified in Sec.  218.142(b);
    (c) Take any marine mammal specified in Sec.  218.142(b) in any 
manner other than as specified in the LOAs; or
    (d) Take a marine mammal specified in Sec.  218.142(b) if NMFS 
determines such taking results in more than a negligible impact on the 
species or stocks of such marine mammal.


Sec.  218.144  Mitigation requirements.

    When conducting the activities identified in Sec.  218.140(c), the 
mitigation measures contained in any LOAs issued under Sec. Sec.  
216.106 of this chapter and 218.146 must be implemented. These 
mitigation measures include, but are not limited to:
    (a) Procedural mitigation. Procedural mitigation is mitigation that 
the Navy must implement whenever and wherever an applicable training or 
testing activity takes place within the NWTT Study Area for acoustic 
stressors (i.e., active sonar, weapons firing noise), explosive 
stressors (i.e., sonobuoys, torpedoes, medium-caliber and large-caliber 
projectiles, missiles, bombs, mine countermeasure and neutralization 
activities, mine neutralization involving Navy divers), and physical 
disturbance and strike stressors (i.e., vessel movement, towed in-water 
devices, small-, medium-, and large-caliber non-explosive practice 
munitions, non-explosive missiles, non-explosive bombs and mine 
shapes).
    (1) Environmental awareness and education. Appropriate Navy 
personnel (including civilian personnel) involved in mitigation and 
training or testing activity reporting under the specified activities 
will 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 the U.S. Navy Afloat 
Environmental Compliance Training Series; Marine Species Awareness 
Training; U.S. Navy Protective Measures Assessment Protocol; and U.S. 
Navy Sonar Positional Reporting System and Marine Mammal Incident 
Reporting.

[[Page 34041]]

    (2) Active sonar. Active sonar includes low-frequency active sonar, 
mid-frequency active sonar, and high-frequency active sonar. For 
vessel-based activities, mitigation applies only to sources that are 
positively controlled and deployed from manned surface vessels (e.g., 
sonar sources towed from manned surface platforms). For aircraft-based 
activities, mitigation applies only to sources that are positively 
controlled and deployed from manned aircraft that do not operate at 
high altitudes (e.g., rotary-wing aircraft). Mitigation does not apply 
to active sonar sources deployed from unmanned aircraft or aircraft 
operating at high altitudes (e.g., maritime patrol aircraft).
    (i) Number of Lookouts and observation platform--(A) For hull-
mounted sources, one Lookout for platforms with space or manning 
restrictions while underway (at the forward part of a small boat or 
ship) and platforms using active sonar while moored or at anchor 
(including pierside); and two Lookouts for platforms without space or 
manning restrictions while underway (at the forward part of the ship).
    (B) For sources that are not hull mounted, One Lookout on the ship 
or aircraft conducting the activity.
    (ii) Mitigation zone and requirements. (A) Prior to the initial 
start of the activity (e.g., when maneuvering on station), Navy 
personnel must observe the mitigation zone for floating vegetation and 
marine mammals; if floating vegetation or a marine mammals is observed, 
Navy personnel must relocate or delay the start of active sonar 
transmission until the mitigation zone is clear of floating vegetation 
or until the conditions in paragraph (a)(2)(ii)(D) of this section are 
met for marine mammals.
    (B) During the activity, for low-frequency active sonar at or above 
200 dB and hull-mounted mid-frequency active sonar, Navy personnel must 
observe the mitigation zone for marine mammals. If a marine mammal is 
observed within 1,000 yd of the sonar source, Navy personnel must power 
down active sonar transmission by 6 dB. If a marine mammal is observed 
within 500 yd of the sonar source, Navy personnel must power down 
active sonar transmission an additional 4 dB (10 dB total). Navy 
personnel must cease transmission if a cetacean or pinniped in the NWTT 
Offshore Area or Western Behm Canal is observed within 200 yd of the 
active sonar source and must cease transmission if a pinniped in NWTT 
Inland Waters is observed within 100 yd of the active sonar source 
(except if hauled out on, or in the water near, man-made structures and 
vessels).
    (C) During the activity, for low-frequency active sonar below 200 
dB, mid-frequency active sonar sources that are not hull-mounted, and 
high-frequency sonar, Navy personnel must observe the mitigation zone 
for marine mammals. Navy personnel must cease transmission if a 
cetacean in the NWTT Offshore Area, NWTT Inshore Area, or Western Behm 
Canal is observed within 200 yd of the sonar source. Navy personnel 
must cease transmission if a pinniped in the NWTT Offshore Area or 
Western Behm Canal is observed within 200 yd of the sonar source and 
must cease transmission if a pinniped in NWTT Inland Waters is observed 
within 100 yd of the active sonar source (except if hauled out on, or 
in the water near, man-made structures and vessels).
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone 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) until 
one of the following conditions has been met: The animal is observed 
exiting the mitigation zone; the animal is thought to have exited the 
mitigation zone based on a determination of its course, speed, and 
movement relative to the sonar source; the mitigation zone has been 
clear from any additional sightings for 10 minutes (min) for aircraft-
deployed sonar sources or 30 min for vessel-deployed sonar sources; for 
mobile activities, the active sonar source has transited a distance 
equal to double that of the mitigation zone size beyond the location of 
the last sighting; or for activities using hull-mounted sonar where a 
dolphin(s) is observed in the mitigation zone, the Lookout concludes 
that the dolphin(s) is deliberately closing in on the ship to ride the 
ship's bow wave, and are therefore out of the main transmission axis of 
the sonar (and there are no other marine mammal sightings within the 
mitigation zone).
    (3) Weapons firing noise. Weapons firing noise associated with 
large-caliber gunnery activities.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on the ship conducting the firing. Depending on the 
activity, the Lookout could be the same as the one provided for under 
``Explosive medium-caliber and large-caliber projectiles'' or under 
``Small-, medium-, and large-caliber non-explosive practice munitions'' 
in paragraphs (a)(6)(i) and (a)(13)(i) of this section.
    (ii) Mitigation zone and requirements. (A) Thirty degrees on either 
side of the firing line out to 70 yd from the muzzle of the weapon 
being fired.
    (B) Prior to the initial start of the activity, Navy personnel must 
observe the mitigation zone for floating vegetation and marine mammals; 
if floating vegetation or a marine mammal is observed, Navy personnel 
must relocate or delay the start of weapons firing until the mitigation 
zone is clear of floating vegetation or until the conditions in 
paragraph (a)(3)(ii)(D) of this section are met for marine mammals.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease weapons firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing weapons firing) until one of the following 
conditions has been met: The animal is observed exiting the mitigation 
zone; the animal is thought to have exited the mitigation zone based on 
a determination of its course, speed, and movement relative to the 
firing ship; the mitigation zone has been clear from any additional 
sightings for 30 min; or for mobile activities, the firing ship has 
transited a distance equal to double that of the mitigation zone size 
beyond the location of the last sighting.
    (4) Explosive sonobuoys--(i) Number of Lookouts and observation 
platform. One Lookout must be positioned in an aircraft or on a small 
boat. If additional platforms are participating in the activity, Navy 
personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for applicable 
biological resources while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 600 yd around an 
explosive sonobuoy.
    (B) Prior to the initial start of the activity (e.g., during 
deployment of a sonobuoy field, which typically lasts 20-30 min), Navy 
personnel must conduct passive acoustic monitoring for marine mammals 
and use information from detections to assist visual observations. Navy 
personnel also must visually observe the mitigation zone for floating 
vegetation and marine mammals; if floating vegetation or a

[[Page 34042]]

marine mammal is observed, Navy personnel must relocate or delay the 
start of sonobuoy or source/receiver pair detonations until the 
mitigation zone is clear of floating vegetation or until the conditions 
in paragraph (a)(4)(ii)(D) of this section are met for marine mammals.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease sonobuoy or source/receiver pair detonations.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following conditions 
has been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
sonobuoy; or the mitigation zone has been clear from any additional 
sightings for 10 min when the activity involves aircraft that have fuel 
constraints, or 30 min when the activity involves aircraft that are not 
typically fuel constrained.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (5) Explosive torpedoes--(i) Number of Lookouts and observation 
platform. One Lookout must be positioned in an aircraft. If additional 
platforms are participating in the activity, Navy personnel positioned 
in those assets (e.g., safety observers, evaluators) must support 
observing the mitigation zone for marine mammals while performing their 
regular duties.
    (ii) Mitigation zone and requirements. (A) 2,100 yd around the 
intended impact location.
    (B) Prior to the initial start of the activity (e.g., during 
deployment of the target), Navy personnel must conduct passive acoustic 
monitoring for marine mammals and use the information from detections 
to assist visual observations. Navy personnel also must visually 
observe the mitigation zone for floating vegetation and marine mammals; 
if floating vegetation or a marine mammal is observed, Navy personnel 
must relocate or delay the start of firing until the mitigation zone is 
clear of floating vegetation or until the conditions in paragraph 
(a)(5)(ii)(D) of this section are met for marine mammals.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals. If a marine mammal is observed, Navy personnel 
must cease firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
intended impact location; or the mitigation zone has been clear from 
any additional sightings for 10 min when the activity involves aircraft 
that have fuel constraints, or 30 min when the activity involves 
aircraft that are not typically fuel constrained.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (6) Explosive medium-caliber and large-caliber projectiles. Gunnery 
activities using explosive medium-caliber and large-caliber 
projectiles. Mitigation applies to activities using a surface target.
    (i) Number of Lookouts and observation platform. One Lookout must 
be on the vessel conducting the activity. For activities using 
explosive large-caliber projectiles, depending on the activity, the 
Lookout could be the same as the one described in ``Weapons firing 
noise'' in paragraph (a)(3)(i) of this section. If additional platforms 
are participating in the activity, Navy personnel positioned in those 
assets (e.g., safety observers, evaluators) must support observing the 
mitigation zone for marine mammals while performing their regular 
duties.
    (ii) Mitigation zone and requirements. (A) 600 yd around the 
intended impact location for explosive medium-caliber projectiles.
    (B) 1,000 yd around the intended impact location for explosive 
large-caliber projectiles.
    (C) Prior to the initial start of the activity (e.g., when 
maneuvering on station), Navy personnel must observe the mitigation 
zone for floating vegetation and marine mammals; if floating vegetation 
or a marine mammal is observed, Navy personnel must relocate or delay 
the start of firing until the mitigation zone is clear of floating 
vegetation or until the conditions in paragraph (a)(6)(ii)(E) are met 
for marine mammals.
    (D) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if a marine mammal is observed, Navy personnel 
must cease firing.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
intended impact location; the mitigation zone has been clear from any 
additional sightings for 30 min for vessel-based firing; or, for 
activities using mobile targets, the intended impact location has 
transited a distance equal to double that of the mitigation zone size 
beyond the location of the last sighting.
    (F) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance),

[[Page 34043]]

these Navy assets must assist in the visual observation of the area 
where detonations occurred.
    (7) Explosive missiles. Aircraft-deployed explosive missiles. 
Mitigation applies to activities using a surface target.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft. If additional platforms are participating 
in the activity, Navy personnel positioned in those assets (e.g., 
safety observers, evaluators) must support observing the mitigation 
zone for marine mammals while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 2,000 yd around the 
intended impact location.
    (B) Prior to the initial start of the activity (e.g., during a fly-
over of the mitigation zone), Navy personnel must observe the 
mitigation zone for floating vegetation and marine mammals; if floating 
vegetation or a marine mammal is observed, Navy personnel must relocate 
or delay the start of firing until the mitigation zone is clear of 
floating vegetation or until the conditions in paragraph (a)(7)(ii)(D) 
are met for marine mammals.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if marine mammals are observed, Navy personnel 
must cease firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
intended impact location; or the mitigation zone has been clear from 
any additional sightings for 10 min when the activity involves aircraft 
that have fuel constraints, or 30 min when the activity involves 
aircraft that are not typically fuel constrained.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (8) Explosive bombs--(i) Number of Lookouts and observation 
platform. One Lookout must be positioned in an aircraft conducting the 
activity. If additional platforms are participating in the activity, 
Navy personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for marine 
mammals while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 2,500 yd around the 
intended target.
    (B) Prior to the initial start of the activity (e.g., when arriving 
on station), Navy personnel must observe the mitigation zone for 
floating vegetation and marine mammals; if floating vegetation or a 
marine mammals is observed, Navy personnel must relocate or delay the 
start of bomb deployment until the mitigation zone is clear of floating 
vegetation or until the conditions in paragraph (a)(8)(ii)(D) of this 
section are met for marine mammals.
    (C) During the activity (e.g., during target approach), Navy 
personnel must observe the mitigation zone for marine mammals; if a 
marine mammal is observed, Navy personnel must cease bomb deployment.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing bomb deployment) until one of the following 
conditions has been met: The animal is observed exiting the mitigation 
zone; the animal is thought to have exited the mitigation zone based on 
a determination of its course, speed, and movement relative to the 
intended target; the mitigation zone has been clear from any additional 
sightings for 10 min; or for activities using mobile targets, the 
intended target has transited a distance equal to double that of the 
mitigation zone size beyond the location of the last sighting.
    (E) After completion of the activity (e.g., prior to maneuvering 
off station), Navy personnel must, when practical (e.g., when platforms 
are not constrained by fuel restrictions or mission-essential follow-on 
commitments), observe for marine mammals in the vicinity of where 
detonations occurred; if any injured or dead marine mammals are 
observed, Navy personnel must follow established incident reporting 
procedures. If additional platforms are supporting this activity (e.g., 
providing range clearance), these Navy assets must assist in the visual 
observation of the area where detonations occurred.
    (9) Explosive mine countermeasure and neutralization activities--
(i) Number of Lookouts and observation platform. (A) One Lookout must 
be positioned on a vessel or in an aircraft when implementing the 
smaller mitigation zone.
    (B) Two Lookouts must be positioned (one in an aircraft and one on 
a small boat) when implementing the larger mitigation zone.
    (C) If additional platforms are participating in the activity, Navy 
personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for marine 
mammals while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 600 yd around the 
detonation site for activities using <=5 lb net explosive weight.
    (B) 2,100 yd around the detonation site for activities using >5-60 
lb net explosive weight.
    (C) Prior to the initial start of the activity (e.g., when 
maneuvering on station; typically, 10 min when the activity involves 
aircraft that have fuel constraints, or 30 min when the activity 
involves aircraft that are not typically fuel constrained), Navy 
personnel must observe the mitigation zone for floating vegetation and 
marine mammals; if floating vegetation or a marine mammal is observed, 
Navy personnel must relocate or delay the start of detonations until 
the mitigation zone is clear of floating vegetation or until the 
conditions in paragraph (ii)(E) are met for marine mammals.
    (D) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if a marine mammal is observed, Navy personnel 
must cease detonations.
    (E) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing detonations) until one of the following conditions 
has been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to detonation 
site; or the mitigation zone has been clear from

[[Page 34044]]

any additional sightings for 10 min when the activity involves aircraft 
that have fuel constraints, or 30 min when the activity involves 
aircraft that are not typically fuel constrained.
    (F) After completion of the activity (typically 10 min when the 
activity involves aircraft that have fuel constraints, or 30 min when 
the activity involves aircraft that are not typically fuel 
constrained), Navy personnel must observe for marine mammals in the 
vicinity of where detonations occurred; if any injured or dead marine 
mammals are observed, Navy personnel must follow established incident 
reporting procedures. If additional platforms are supporting this 
activity (e.g., providing range clearance), these Navy assets must 
assist in the visual observation of the area where detonations 
occurred.
    (10) Explosive mine neutralization activities involving Navy 
divers--(i) Number of Lookouts and observation platform. (A) Two 
Lookouts (two small boats with one Lookout each (one of which must be a 
Navy biologist)).
    (B) All divers placing the charges on mines must support the 
Lookouts while performing their regular duties and will report 
applicable sightings to their supporting small boat or Range Safety 
Officer.
    (C) If additional platforms are participating in the activity, Navy 
personnel positioned in those assets (e.g., safety observers, 
evaluators) must support observing the mitigation zone for marine 
mammals while performing their regular duties.
    (ii) Mitigation zone and requirements. (A) 500 yd around the 
detonation site during activities using >0.5-2.5 lb net explosive 
weight.
    (B) Prior to the initial start of the activity (e.g., starting 30 
min before the first planned detonation), Navy personnel must observe 
the mitigation zone for floating vegetation and marine mammals; if 
floating vegetation is observed, Navy personnel must relocate or delay 
the start of detonations until the mitigation zone is clear of floating 
vegetation. If a marine mammal is observed, Navy personnel must ensure 
the area is clear of marine mammals for 30 min prior to commencing a 
detonation. A Navy biologist must serve as the lead Lookout and must 
make the final determination that the mitigation zone is clear of any 
floating vegetation or marine mammals prior to the commencement of a 
detonation. The Navy biologist must maintain radio communication with 
the unit conducting the event and the other Lookout.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if a marine mammal is observed, Navy personnel 
must cease detonations. To the maximum extent practicable depending on 
mission requirements, safety, and environmental conditions, Navy 
personnel must position boats near the midpoint of the mitigation zone 
radius (but outside of the detonation plume and human safety zone), 
must position themselves on opposite sides of the detonation location 
(when two boats are used), and must travel in a circular pattern around 
the detonation location with one Lookout observing inward toward the 
detonation site and the other observing outward toward the perimeter of 
the mitigation zone. Navy personnel must only use positively controlled 
charges (i.e., no time-delay fuses). Navy personnel must use the 
smallest practicable charge size for each activity. All activities must 
be conducted in Beaufort sea state number 2 conditions or better and 
must not be conducted in low visibility conditions.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted animal to leave the mitigation zone prior to the initial start 
of the activity (by delaying the start) or during the activity (by not 
recommencing detonations) until one of the following conditions has 
been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
detonation site; or the mitigation zone has been clear from any 
additional sightings for 30 min.
    (E) After each detonation and completion of an activity the Navy 
must observe for marine mammals for 30 min Navy personnel must observe 
for marine mammals in the vicinity of where detonations occurred and 
immediately downstream of the detonation location; if any injured or 
dead marine mammals are observed, Navy personnel must follow 
established incident reporting procedures. If additional platforms are 
supporting this activity (e.g., providing range clearance), these Navy 
assets must assist in the visual observation of the area where 
detonations occurred.
    (F) At the Hood Canal Explosive Ordnance Disposal Range and 
Crescent Harbor Explosive Ordnance Disposal Range, Navy personnel must 
obtain permission from the appropriate designated Command authority 
prior to conducting explosive mine neutralization activities involving 
the use of Navy divers.
    (G) At the Hood Canal Explosive Ordnance Disposal Range, during 
February, March, and April (the juvenile migration period for Hood 
Canal Summer Run Chum), Navy personnel must not use explosives in bin 
E3 (>0.5-2.5 lb net explosive weight), and must instead use explosives 
in bin E0 (<0.1 lb net explosive weight).
    (H) At the Hood Canal Explosive Ordnance Disposal Range, during 
August, September, and October (the adult migration period for Hood 
Canal summer-run chum and Puget Sound Chinook), Navy personnel must 
avoid the use of explosives in bin E3 (>0.5-2.5 lb net explosive 
weight), and must instead use explosive bin E0 (<0.1 lb net explosive 
weight) to the maximum extent practicable unless necessitated by 
mission requirements.
    (I) At the Crescent Harbor Explosive Ordnance Disposal Range, Navy 
personnel must conduct explosive activities at least 1,000 meters (m) 
from the closest point of land to avoid or reduce impacts on fish 
(e.g., bull trout) in nearshore habitat areas.
    (11) Vessel movement. The mitigation will not be applied if: The 
vessel's safety is threatened; the vessel is restricted in its ability 
to maneuver (e.g., during launching and recovery of aircraft or landing 
craft, during towing activities, when mooring, during Transit 
Protection Program exercises, and other events involving escort 
vessels); the vessel is operated autonomously; or when impractical 
based on mission requirements (e.g., during test body retrieval by 
range craft).
    (i) Number of Lookouts and observation platform. One Lookout must 
be on the vessel that is underway.
    (ii) Mitigation zone and requirements. (A) 500 yd around whales for 
surface vessels other than small boats.
    (B) 200 yd around all marine mammals other than whales (except bow-
riding dolphins and pinnipeds hauled out on man-made navigational 
structures, port structures, and vessels) for surface vessels other 
than small boats.
    (C) 100 yd around marine mammals (except bow-riding dolphins and 
pinnipeds hauled out on man-made navigational structures, port 
structures, and vessels) for small boats, such as range craft.
    (D) During the activity (when underway), Navy personnel must 
observe the mitigation zone for marine mammals; if a marine mammal is 
observed, Navy personnel must maneuver to maintain distance.
    (E) Prior to Small Boat Attack exercises at Naval Station Everett, 
Naval Base Kitsap Bangor, or Naval Base

[[Page 34045]]

Kitsap Bremerton, Navy event planners must coordinate with Navy 
biologists during the event planning process. Navy biologists must work 
with NMFS to determine the likelihood of marine mammal presence in the 
planned training location. Navy biologists must notify event planners 
of the likelihood of species presence as they plan specific details of 
the event (e.g., timing, location, duration). Navy personnel must 
provide additional environmental awareness training to event 
participants. The training must alert participating ship crews to the 
possible presence of marine mammals in the training location. Lookouts 
must use the information to assist their visual observation of 
applicable mitigation zones and to aid in the implementation of 
procedural mitigation.
    (iii) Incident reporting procedures. If a marine mammal vessel 
strike occurs, Navy personnel must follow the established incident 
reporting procedures.
    (12) Towed in-water devices. Mitigation applies to devices that are 
towed from a manned surface platform or manned aircraft, or when a 
manned support craft is already participating in an activity involving 
in-water devices being towed by unmanned platforms. The mitigation will 
not be applied if the safety of the towing platform or in-water device 
is threatened.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on a manned towing platform or support craft.
    (ii) Mitigation zone and requirements. (A) 250 yd around marine 
mammals (except bow-riding dolphins and pinnipeds hauled out on man-
made navigational structures, port structures, and vessels) for in-
water devices towed by aircraft or surface vessels other than small 
boats.
    (B) 100 yd around marine mammals (except bow-riding dolphins and 
pinnipeds hauled out on man-made navigational structures, port 
structures, and vessels) for in-water devices towed by small boats, 
such as range craft.
    (C) During the activity (i.e., when towing an in-water device), 
Navy personnel must observe the mitigation zone for marine mammals; if 
a marine mammal is observed, Navy personnel must maneuver to maintain 
distance.
    (13) Small-, medium-, and large-caliber non-explosive practice 
munitions. Gunnery activities using small-, medium-, and large-caliber 
non-explosive practice munitions. Mitigation applies to activities 
using a surface target.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned on the platform conducting the activity. Depending on the 
activity, the Lookout could be the same as the one described for 
``Weapons firing noise'' in paragraph (a)(3)(i) of this section.
    (ii) Mitigation zone and requirements. (A) 200 yd around the 
intended impact location.
    (B) Prior to the initial start of the activity (e.g., when 
maneuvering on station), Navy personnel must observe the mitigation 
zone for floating vegetation and marine mammals; if floating vegetation 
or a marine mammal is observed, Navy personnel must relocate or delay 
the start until the mitigation zone is clear of floating vegetation or 
until the conditions in paragraph (a)(13)(ii)(D) of this section are 
met for marine mammals.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if a marine mammal is observed, Navy personnel 
must cease firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting before or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
intended impact location; the mitigation zone has been clear from any 
additional sightings for 10 min for aircraft-based firing or 30 min for 
vessel-based firing; or for activities using a mobile target, the 
intended impact location has transited a distance equal to double that 
of the mitigation zone size beyond the location of the last sighting.
    (14) Non-explosive missiles. Aircraft-deployed non-explosive 
missiles. Mitigation applies to activities using a surface target.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft.
    (ii) Mitigation zone and requirements. (A) 900 yd around the 
intended impact location.
    (B) Prior to the initial start of the activity (e.g., during a fly-
over of the mitigation zone), Navy personnel must observe the 
mitigation zone for floating vegetation and marine mammals; if floating 
vegetation or a marine mammal is observed, Navy personnel must relocate 
or delay the start of firing until the mitigation zone is clear of 
floating vegetation or until the conditions in paragraph (a)(14)(ii)(D) 
of this section are met for marine mammals.
    (C) During the activity, Navy personnel must observe the mitigation 
zone for marine mammals; if a marine mammal is observed, Navy personnel 
must cease firing.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting prior to or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing firing) until one of the following conditions has 
been met: The animal is observed exiting the mitigation zone; the 
animal is thought to have exited the mitigation zone based on a 
determination of its course, speed, and movement relative to the 
intended impact location; or the mitigation zone has been clear from 
any additional sightings for 10 min when the activity involves aircraft 
that have fuel constraints, or 30 min when the activity involves 
aircraft that are not typically fuel constrained.
    (15) Non-explosive bombs and mine shapes. Non-explosive bombs and 
non-explosive mine shapes during mine laying activities.
    (i) Number of Lookouts and observation platform. One Lookout must 
be positioned in an aircraft.
    (ii) Mitigation zone and requirements. (A) 1,000 yd around the 
intended target.
    (B) Prior to the initial start of the activity (e.g., when arriving 
on station), Navy personnel must observe the mitigation zone for 
floating vegetation and marine mammals; if floating vegetation or a 
marine mammal is observed, Navy personnel must relocate or delay the 
start of bomb deployment or mine laying until the mitigation zone is 
clear of floating vegetation or until the conditions in paragraph 
(a)(15)(ii)(D) of section are met for marine mammals.
    (C) During the activity (e.g., during approach of the target or 
intended minefield location), Navy personnel must observe the 
mitigation zone for marine mammals and, if a marine mammal is observed, 
Navy personnel must cease bomb deployment or mine laying.
    (D) Commencement/recommencement conditions after a marine mammal 
sighting prior to or during the activity. Navy personnel must allow a 
sighted marine mammal to leave the mitigation zone prior to the initial 
start of the activity (by delaying the start) or during the activity 
(by not recommencing bomb deployment or mine laying) until one of the 
following conditions has been met:

[[Page 34046]]

The animal is observed exiting the mitigation zone; the animal is 
thought to have exited the mitigation zone based on a determination of 
its course, speed, and movement relative to the intended target or 
minefield location; the mitigation zone has been clear from any 
additional sightings for 10 min; or for activities using mobile 
targets, the intended target has transited a distance equal to double 
that of the mitigation zone size beyond the location of the last 
sighting.
    (b) Mitigation areas. In addition to procedural mitigation, Navy 
personnel must implement mitigation measures within mitigation areas to 
avoid or reduce potential impacts on marine mammals.
    (1) Mitigation areas for marine mammals for NWTT Study Area for 
sonar, explosives, and physical disturbance and vessel strikes--(i) 
Mitigation area requirements--(A) Marine Species Coastal Mitigation 
Area (year round). (1) Within 50 nmi from shore in the Marine Species 
Coastal Mitigation Area, Navy personnel must not conduct: Explosive 
training activities; explosive testing activities (with the exception 
of explosive Mine Countermeasure and Neutralization Testing 
activities); and non-explosive missile training activities. Should 
national security require conducting these activities in the mitigation 
area, Navy personnel must obtain permission from the appropriate 
designated Command authority prior to commencement of the activity. 
Navy personnel must provide NMFS with advance notification and include 
information about the event in its annual activity reports to NMFS.
    (2) Within 20 nmi from shore in the Marine Species Coastal 
Mitigation Area, Navy personnel must not conduct non-explosive large-
caliber gunnery training activities and non-explosive bombing training 
activities. Should national security require conducting these 
activities in the mitigation area, Navy personnel must obtain 
permission from the appropriate designated Command authority prior to 
commencement of the activity. Navy personnel must provide NMFS with 
advance notification and include information about the event in its 
annual activity reports to NMFS.
    (3) Within 12 nmi from shore in the Marine Species Coastal 
Mitigation Area, Navy personnel must not conduct: Non-explosive small- 
and medium-caliber gunnery training activities; non-explosive torpedo 
training activities; and Anti-Submarine Warfare Tracking Exercise--
Helicopter, Maritime Patrol Aircraft, Ship, or Submarine training 
activities. Should national security require conducting these 
activities in the mitigation area, Navy personnel must obtain 
permission from the appropriate designated Command authority prior to 
commencement of the activity. Navy personnel must provide NMFS with 
advance notification and include information about the event in its 
annual activity reports to NMFS.
    (B) Olympic Coast National Marine Sanctuary Mitigation Area (year-
round). (1) Within the Olympic Coast National Marine Sanctuary 
Mitigation Area, Navy personnel must not conduct more than 32 hours of 
MF1 mid-frequency active sonar during training annually and will not 
conduct non-explosive bombing training activities. Should national 
security require conducting more than 32 hours of MF1 mid-frequency 
active sonar during training annually or conducting non-explosive 
bombing training activities in the mitigation area, Navy personnel must 
obtain permission from the appropriate designated Command authority 
prior to commencement of the activity. Navy personnel must provide NMFS 
with advance notification and include information about the event in 
its annual activity reports to NMFS.
    (2) Within the Olympic Coast National Marine Sanctuary Mitigation 
Area, Navy personnel must not conduct more than 33 hours of MF1 mid-
frequency active sonar during testing annually (except within the 
portion of the mitigation area that overlaps the Quinault Range Site) 
and must not conduct explosive Mine Countermeasure and Neutralization 
Testing activities. Should national security require conducting more 
than 33 hours of MF1 mid-frequency active sonar during testing annually 
(except within the portion of the mitigation area that overlaps the 
Quinault Range Site) or conducting explosive Mine Countermeasure and 
Neutralization Testing activities in the mitigation area, Navy 
personnel must obtain permission from the appropriate designated 
Command authority prior to commencement of the activity. Navy personnel 
must provide NMFS with advance notification and include information 
about the event in its annual activity reports to NMFS.
    (C) Stonewall and Heceta Bank Humpback Whale Mitigation Area (May 
1-November 30). Within the Stonewall and Heceta Bank Humpback Whale 
Mitigation Area, Navy personnel must not use MF1 mid-frequency active 
sonar or explosives during training and testing from May 1 to November 
30. Should national security require using MF1 mid-frequency active 
sonar or explosives during training and testing from May 1 to November 
30, Navy personnel must obtain permission from the appropriate 
designated Command authority prior to commencement of the activity. 
Navy personnel must provide NMFS with advance notification and include 
information about the event in its annual activity reports to NMFS.
    (D) Point St. George Humpback Whale Mitigation Area (July 1-
November 30). Within the Point St. George Humpback Whale Mitigation 
Area, Navy personnel must not use MF1 mid-frequency active sonar or 
explosives during training and testing from July 1 to November 30. 
Should national security require using MF1 mid-frequency active sonar 
or explosives during training and testing from July 1 to November 30, 
Navy personnel must obtain permission from the appropriate designated 
Command authority prior to commencement of the activity. Navy personnel 
must provide NMFS with advance notification and include information 
about the event in its annual activity reports to NMFS.
    (E) Puget Sound and Strait of Juan de Fuca Mitigation Area (year-
round). (1) Within the Puget Sound and Strait of Juan de Fuca 
Mitigation Area, Navy personnel must obtain approval from the 
appropriate designated Command authority prior to: The use of hull-
mounted mid-frequency active sonar during training while underway or 
conducting ship and submarine active sonar pierside maintenance or 
testing.
    (2) Within the Puget Sound and Strait of Juan de Fuca Mitigation 
Area for Civilian Port Defense--Homeland Security Anti-Terrorism/Force 
Protection Exercises, Navy personnel must coordinate with Navy 
biologists during the event planning process. Navy biologists must work 
with NMFS to determine the likelihood of gray whale and Southern 
Resident Killer Whale presence in the planned training location. Navy 
biologists must notify Navy event planners of the likelihood of species 
presence as they plan specific details of the event (e.g., timing, 
location, duration). Navy personnel must ensure environmental awareness 
of event participants. Environmental awareness will help alert 
participating ship and aircraft crews to the possible presence of 
marine mammals in the training location, such as gray whales and 
Southern Resident Killer Whales.
    (F) Northern Puget Sound Gray Whale Mitigation Area (March 1-May 
31). Within the Northern Puget Sound Gray Whale Mitigation Area, Navy 
personnel must not conduct Civilian Port Defense--Homeland Security 
Anti-Terrorism/Force Protection Exercises from March 1 to May 31. 
Should national security require conducting

[[Page 34047]]

Civilian Port Defense--Homeland Security Anti-Terrorism/Force 
Protection Exercises from March 1 to May 31, Navy personnel must obtain 
permission from the appropriate designated Command authority prior to 
commencement of the activity. Navy personnel must provide NMFS with 
advance notification and include information about the event in its 
annual activity reports to NMFS.
    (ii) [Reserved]


Sec.  218.145  Requirements for monitoring and reporting.

    (a) Unauthorized take. Navy personnel must notify NMFS immediately 
(or as soon as operational security considerations allow) if the 
specified activity identified in Sec.  218.140 is thought to have 
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.
    (b) Monitoring and reporting under the LOAs. The Navy must conduct 
all monitoring and reporting required under the LOAs, including abiding 
by the U.S. Navy's Marine Species Monitoring Program. Details on 
program goals, objectives, project selection process, and current 
projects are available at www.navymarinespeciesmonitoring.us.
    (c) Notification of injured, live stranded, or dead marine mammals. 
The Navy must consult 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 NWTT Study Area marine species monitoring report. The 
Navy must submit an annual report of the NWTT Study Area monitoring 
describing the implementation and results from the previous calendar 
year. Data collection methods must be standardized across range 
complexes and study areas to allow for comparison in different 
geographic locations. The report must be submitted to the Director, 
Office of Protected Resources, NMFS, either within three months after 
the end of the calendar year, or within three months after the 
conclusion of the monitoring year, to be determined by the Adaptive 
Management process. NMFS will submit comments or questions on the 
report, if any, within one month of receipt. The report will be 
considered final after the Navy has addressed NMFS' comments, or one 
month after submittal of the draft if NMFS does not provide comments on 
the draft report. This report will describe progress of knowledge made 
with respect to intermediate scientific objectives within the NWTT 
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 does not provide 
direct assessment of cumulative progress on the monitoring plan study 
questions. As an alternative, the Navy may submit a multi-range complex 
annual monitoring plan report to fulfill this requirement. Such a 
report will describe progress of knowledge made with respect to 
monitoring study questions across multiple Navy ranges associated with 
the ICMP. Similar study questions must be treated together so that 
progress on each topic can be summarized across multiple Navy ranges. 
The report need not include analyses and content that does not provide 
direct assessment of cumulative progress on the monitoring study 
question. This will continue to allow the Navy to provide a cohesive 
monitoring report covering multiple ranges (as per ICMP goals), rather 
than entirely separate reports for the NWTT, Hawaii-Southern 
California, Gulf of Alaska, and Mariana Islands Study Areas.
    (e) Annual NWTT Study Area training exercise report and testing 
activity reports. Each year, the Navy must submit two preliminary 
reports (Quick Look Report) detailing the status of applicable sound 
sources within 21 days after the anniversary of the date of issuance of 
each LOA to the Director, Office of Protected Resources, NMFS. Each 
year, the Navy must submit a detailed report to the Director, Office of 
Protected Resources, NMFS, within three months after the one-year 
anniversary of the date of issuance of the LOA. NMFS will submit 
comments or questions on the report, if any, within one month of 
receipt. The report will be considered final after the Navy has 
addressed NMFS' comments, or one month after submittal of the draft if 
NMFS does not provide comments on the draft report. The NWTT Annual 
Training Exercise Report and Testing Activity Report can be 
consolidated with other exercise reports from other range complexes in 
the Pacific Ocean for a single Pacific Exercise Report, if desired. The 
annual report must contain information on the total hours of operation 
of MF1 surface ship hull-mounted mid-frequency active sonar used during 
training and testing activities in the Olympic Coast National Marine 
Sanctuary Mitigation Area and a summary of all sound sources used, 
including within specific mitigation reporting areas as described in 
paragraph (e)(2) 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 annual 
report 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 a given year, 
or cumulatively, the report must 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 NWTT SEIS/OEIS and MMPA final rule. The 
annual report must also include details regarding specific requirements 
associated with the mitigation areas listed in Sec.  218.144(b). The 
analysis in the detailed report will be based on the accumulation of 
data from the current year's report and data collected from previous 
reports. The final annual/close-out report at the conclusion of the 
authorization period (year seven) will serve as the comprehensive 
close-out report and include both the final year annual incidental take 
compared to annual authorized incidental take as well as a cumulative 
seven-year incidental take compared to seven-year authorized incidental 
take. The detailed reports must contain information identified in 
paragraphs (e)(1) through (3) of this section.
    (1) 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) Total annual hours or quantity (per the LOA) of each bin of 
sonar and other transducers, and
    (ii) Total annual expended/detonated ordinance (missiles, bombs, 
sonobuoys, etc.) for each explosive bin.
    (2) NWTT Study Area Mitigation Areas. The report must include any 
Navy activities that occurred as specifically described in areas 
identified in Sec.  218.144(b). Information included in the classified 
annual reports may be used to inform future adaptive management of 
activities within the NWTT Study Area.
    (3) Geographic information presentation. The reports must present 
an annual (and seasonal, where practical) depiction of training and

[[Page 34048]]

testing bin usage geographically across the NWTT Study Area.
    (f) Seven-year close-out report. The final (year seven) draft 
annual/close-out report must be submitted within three months after the 
expiration of this subpart to the Director, Office of Protected 
Resources, NMFS. NMFS will submit comments on the draft close-out 
report, if any, within three months of receipt. The report will be 
considered final after the Navy has addressed NMFS' comments, or three 
months after submittal of the draft if NMFS does not provide comments 
on the draft report.


Sec.  218.146  Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to this subpart, 
the Navy must apply for and obtain an LOA in accordance with Sec.  
216.106 of this chapter.
    (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) If an LOA expires prior to the expiration date of this subpart, 
the Navy may apply for and obtain a renewal of the LOA.
    (d) In the event of projected changes to the activity or to 
mitigation, monitoring, or reporting (excluding changes made pursuant 
to the adaptive management provision of Sec.  218.147(c)(1)) required 
by an LOA issued under this subpart, the Navy must apply for and obtain 
a modification of the LOA as described in Sec.  218.147.
    (e) 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.
    (f) Issuance of the LOA(s) will be based on a determination that 
the level of taking is consistent with the findings made for the total 
taking allowable under this subpart.
    (g) Notice of issuance or denial of the LOA(s) will be published in 
the Federal Register within 30 days of a determination.


Sec.  218.147  Renewals and modifications of Letters of Authorization.

    (a) An LOA issued under Sec. Sec.  216.106 of this chapter and 
218.146 for the activity identified in Sec.  218.140(c) may be renewed 
or modified upon request by the applicant, provided that:
    (1) The planned specified activity and mitigation, monitoring, and 
reporting measures, as well as the anticipated impacts, are the same as 
those described and analyzed for 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 LOA(s) were implemented.
    (b) For LOA modification or renewal requests by the applicant 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) that do not 
change the findings made for this subpart or result in no more than a 
minor change in the total estimated number of takes (or distribution by 
species or stock or years), NMFS may publish a notice of planned 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 of this chapter and 
218.146 may be modified by NMFS under the following circumstances:
    (1) Through Adaptive Management, after consulting with the Navy 
regarding the practicability of the modifications, NMFS may modify 
(including adding or removing measures) 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.
    (i) Possible sources of data that could contribute to the decision 
to modify the mitigation, monitoring, or reporting measures in an LOA 
include:
    (A) Results from the Navy's monitoring 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 
will publish a notice of planned LOA in the Federal Register and 
solicit public comment.
    (2) If NMFS 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 218.146, an LOA may be modified without prior notice or 
opportunity for public comment. Notice would be published in the 
Federal Register within thirty days of the action.


Sec.  218.148  [Reserved]

[FR Doc. 2020-08533 Filed 5-22-20; 11:15 am]
BILLING CODE 3510-22-P