[Federal Register Volume 91, Number 139 (Wednesday, July 22, 2026)]
[Notices]
[Pages 46055-46079]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-14816]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF841]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Office of Naval Research's
Arctic Research Activities in the Beaufort and Chukchi Seas (Year 9)
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from the Office of Naval Research
(ONR) for authorization to take marine mammals incidental to Arctic
Research Activities (ARA) in the Beaufort Sea and eastern Chukchi Sea.
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting
comments on its proposal to issue an incidental harassment
authorization (IHA) to incidentally take marine mammals during the
specified activity. NMFS is also requesting comments on a possible one-
time, 1-year renewal that could be issued under certain circumstances
and if all requirements are met, as described in Request for Public
Comments at the end of this notice. NMFS will consider public comments
prior to making any final decision on the issuance of the requested
MMPA authorization and agency responses will be summarized in the final
notice of our decision. ONR's activities are considered 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 August
21, 2026.
ADDRESSES: Comments should be addressed to Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service and should be submitted via email to [email protected].
Electronic copies of the application and supporting documents, as well
as a list of the references cited in this document, may be obtained
online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems accessing these documents, please call
the contact listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Alyssa Clevenstine, Office of
Protected Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
[[Page 46056]]
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). If such findings are made, NMFS must prescribe the
permissible methods of taking; other ``means of effecting the least
practicable adverse impact'' on the affected species or stocks and
their habitat, paying particular attention to rookeries, mating
grounds, and areas of similar significance, and on the availability of
the species or stocks for taking for certain subsistence uses (referred
to as ``mitigation''); and requirements pertaining to the monitoring
and reporting of the takings. The definitions of all applicable MMPA
statutory terms used above are included in the relevant sections below
(see also 16 U.S.C. 1362; 50 CFR 216.3, 216.103).
The 2004 NDAA (Pub. L. 108-136) removed the ``small numbers'' and
``specified geographical region'' limitations indicated above and
amended the definition of ``harassment'' as applied to a ``military
readiness activity.'' The activity for which incidental take of marine
mammals is being requested qualifies as a military readiness activity.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for NAO 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS has preliminarily determined
that the issuance of the proposed IHA qualifies to be categorically
excluded from further NEPA review.
Summary of Request
On June 4, 2026, NMFS received a request from ONR for an IHA to
take marine mammals incidental to ARA in the Beaufort and Chukchi Seas.
Following NMFS' review of the application, ONR submitted a revised
version on June 18, 2026. The application was deemed adequate and
complete on June 24, 2026. ONR's request is for take of beluga whales
and ringed seals by Level B harassment only. Neither ONR nor NMFS
expect serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
This proposed IHA would cover the ninth year of a larger project
for which ONR obtained prior IHAs and renewal IHAs (83 FR 48799,
September 27, 2018; 84 FR 50007, September 24, 2019; 85 FR 53333,
August 28, 2020; 86 FR 54931, October 5, 2021; 87 FR 57458, September
20, 2022; 88 FR 65657, September 18, 2023; 89 FR 77089, September 14,
2024; 90 FR 43178, September 14, 2025). ONR has complied with all the
requirements (e.g., mitigation, monitoring, and reporting) of the
previous IHAs, and information regarding their monitoring results may
be found in the Estimated Take of Marine Mammals section.
Description of Proposed Activity
Overview
ONR proposes to conduct scientific experiments in support of ARA
using active acoustic sources within the Beaufort and Chukchi Seas.
Project activities involve acoustic testing and a multi-frequency
navigation system concept test using left-behind active acoustic
sources. The proposed experiments involve the deployment of moored,
drifting, and ice-tethered active acoustic sources from the Research
Vessel (R/V) Sikuliaq. Recovery of equipment may be from R/V Sikuliaq,
U.S. Coast Guard Cutter (CGC) HEALY, or another vessel, and icebreaking
may be required. Underwater sound from the active acoustic sources and
noise from icebreaking may result in Level B harassment of marine
mammals.
Dates and Duration
The proposed activity would occur from September 2026 through
September 2027 and include up to two research cruises. Acoustic testing
would take place during the cruises, with the first cruise beginning
September 22, 2026, and a potential second cruise occurring in summer
2027, which may include up to 8 days of icebreaking activities.
Acoustic sources would operate year-round and would be deployed and
recovered during the research cruises.
Geographic Region
The proposed activity would occur across the U.S. Exclusive
Economic Zone (EEZ) in the Beaufort and Chukchi Seas, partially in the
high seas north of Alaska, the global commons, and within a part of the
Canadian EEZ (for which Navy would obtain the appropriate permits)
(figure 1). The proposed activity would primarily occur in the Beaufort
Sea but the analysis considers the drifting of active sources on buoys
into the eastern portion of the Chukchi Sea. The closest point of the
Study Area to the Alaska coast is 204 kilometers (km) (110 nautical
miles). The proposed Study Area is approximately 639,237 square
kilometers (km\2\).
BILLING CODE 3510-22-P
[[Page 46057]]
[GRAPHIC] [TIFF OMITTED] TN22JY26.023
Figure 1--Arctic Research Activities Study Area and Mooring Locations
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
ONR's ARA include multiple scientific objectives that support the
Arctic and Global Prediction Program, including Arctic Mobile Observing
System (AMOS). The proposed activity constitutes the development of a
new system under AMOS involving very-low-, low-, and mid-frequency
(VLF, LF, and MF) transmissions (35 Hertz (Hz), 900 Hz, and 10
kilohertz (kHz)) (the former not applicable to Year 9), utilizing
acoustic sources and receivers to provide a means of performing under-
[[Page 46058]]
ice navigation for autonomous underwater vehicles (AUVs), including
gliders and unmanned undersea vehicles (UUVs). This would allow for the
possibility of year-round scientific observations of Arctic
environmental phenomena. As an environment particularly affected by
climate change, year-round observations under a variety of ice
conditions are required to study the effects of this changing
environment for military readiness, as well as the implications of
environmental change to humans and animals. VLF technology is an
important method of observing ocean warming, and the continued
development of these types of acoustic sources would allow for
characterization of larger areas. The technology also has the potential
to allow for development and use of navigational systems that would not
be heard by some marine mammal species and, therefore, would be less
impactful.
Up to six moorings (fixed acoustic navigation sources transmitting
at 900 Hz) and two drifting ice gateway buoys (IGBs) would be
configured with active acoustic sources and would operate for a period
of 1 year. ONR does not expect to use VLF sources (35 Hz) from
September 2026 through September 2027 due to hardware availability.
Further, no UUV use is planned during the September 2026 cruise but it
may be included in future test plans during the period of the proposed
IHA; however, NMFS has considered these sources herein to account for
their potential use.
The proposed activity would utilize non-impulsive acoustic sources,
although not all sources will cause take of marine mammals (tables 1,
2). Marine mammal takes would arise from the operation of non-impulsive
active sources. Although not currently planned, icebreaking could occur
as part of this proposed activity if a research vessel needs to return
to the Study Area before the end of the IHA period to ensure scientific
objectives are met. Underwater sound from the active acoustic sources
and noise from icebreaking may result in take by Level B harassment of
marine mammals.
Below are descriptions of the platforms and equipment that would be
deployed at different times during the proposed activity.
Research Vessels
The R/V Sikuliaq would perform the research cruise in September
2026 and conduct testing of acoustic sources during the cruise, as well
as deploy leave behind sources to operate as a year-round navigation
system observation. The vessel to be used in a potential 2027 cruise is
yet to be determined but would likely be either the R/V Sikuliaq or the
CGC HEALY.
The R/V Sikuliaq has a maximum speed of approximately 22.2 km per
hour (km/hr) with a cruising speed of 20.4 km/hr. The R/V Sikuliaq is
not an icebreaking ship but an ice strengthened ship, so it would not
be icebreaking. Therefore, acoustic signatures of icebreaking for the
R/V Sikuliaq are not relevant. CGC HEALY travels at a maximum speed of
31.5 km/hr with a cruising speed of 22.2 km/hr and a maximum speed of
5.6 km/hr when traveling through 1.07 m of sea ice. While no
icebreaking cruise on the CGC HEALY is planned, this proposed IHA
considers an icebreaking cruise in case the need arises. The R/V
Sikuliaq, CGC HEALY, or any other vessel operating a research cruise
associated with the proposed activity may perform the following
activities during their research cruises:
Deployment of moored and/or ice-tethered passive sensors
(oceanographic measurement devices, acoustic receivers);
Deployment of moored and/or ice-tethered active acoustic
sources to transmit acoustic signals;
Deployment of AUVs;
Deployment of drifting buoys, with or without acoustic
sources; or,
Recovery of equipment.
Glider Surveys
Glider surveys are proposed for the research cruise. All gliders
would be recovered; some may be recovered during the cruise, but the
remainder would be recovered at a later date. Long-endurance,
autonomous sea gliders are intended for use in extended missions in
ice-covered waters. Gliders are buoyancy-driven, equipped with
satellite modems providing two-way communication, and can transit to
depths of up to 1,000 m. Gliders would collect data in the area of the
shallow water sources and moored sources, moving at a speed of 0.25
meters per second, approximately 23 km per day. A combination of recent
advances in sea glider technology would provide full-year endurance.
When operating in ice-covered waters, gliders navigate by trilateration
(the process of determining location by measurement of distances, using
the geometry of circles, spheres, or triangles) from moored acoustic
sound sources (or dead reckoning should navigation signals be
unavailable). Hibernating gliders would continue to track their
position, waking to reposition should they drift too far from their
target region. Gliders measure temperature, salinity, dissolved oxygen,
rates of dissipation of temperature variance (and vertical turbulent
diffusivity), and multi-spectral down-welling irradiance.
Moored and Drifting Acoustic Sources
During the September 2026 cruise, active acoustic sources would be
lowered from the cruise vessel while stationary, deployed on AUVs, or
deployed on fixed AMOS moorings for intermittent testing of the system
components. The testing would take place in the vicinity of the source
locations in figure 1. During this testing, 900 Hz, 10 kHz, and
acoustic modems would be employed.
Up to six fixed acoustic navigation sources transmitting at 900 Hz
would remain in place for 1 year. These moorings would be anchored on
the seabed and held in the water column with subsurface buoys. All
sources would be deployed by shipboard winches, which would lower
sources and receivers in a controlled manner. Anchors would be steel
``wagon wheels'' typically used for this type of deployment. Two
drifting IGBs would also be configured with active acoustic sources.
Table 1--Characteristics of Modeled Acoustic Sources
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Signal strength (dB
Platform (total number deployed) Acoustic source Purpose/function Frequency re 1 [micro]Pa at 1 Bandwidth Pulse width/duty
m) cycle
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REMUS 600 UUV (up to 1)......... WHOI Micro-modem... Acoustic 900-950 Hz....... NTE 180 dB by 50 Hz........... 5 pings/hour with
communications. system design 30 sec pulse
limits. length.
REMUS 600 UUV (up to 1)......... UUV/WHOI Micro- Acoustic 8-14 kHz......... NTE 185 dB by 5 kHz........... 10% average duty
modem. communications. system design cycle, with 4 sec
limits. pulse length.
IGB (drifting).................. WHOI Micro-modem... Acoustic 900-950 Hz....... NTE 180 dB by 50 Hz........... Transmit every 4
(2)............................. communications. system design hours, 30 sec
limits. pulse length.
[[Page 46059]]
IGB (drifting).................. WHOI Micro-modem... Acoustic 8-14 kHz......... NTE 185 dB by 5 kHz........... Typically receive
(2)............................. communications. system design only; transmit is
limits. very
intermittent.
Mooring (6)..................... WHOI Micro-modem Acoustic Navigation 900-950 Hz....... NTE 180 dB by 50 Hz........... Transmit every 4
(6). system design hours, 30 sec
limits. pulse length.
Mooring (2) *................... VLF................ Acoustic Navigation 35 Hz............ NTE 190 dB......... 6 Hz............ Up to 4 times per
day, 10 minutes
each.
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Note: dB re 1 [micro]Pa at 1 m = decibels referenced to 1 microPascal at 1 meter; WHOI = Woods Hole Oceanographic Institution; Hz = Hertz; NTE = not to
exceed; sec = second; IGB = Ice Gateway Buoy; kHz = kilohertz. REMUS use is not anticipated during the September 2026 cruise but is included in case
of future use during the proposed IHA period.
* No VLF sources (35 Hz) would be used in Year 9 due to hardware availability.
De Minimis Sources
The following activities and sources are unlikely to result in take
of marine mammals. These activities are described here but they are not
discussed further in this notice. ONR characterizes de minimis sources
as those with the following parameters: low source levels (SLs), narrow
beams, downward directed transmission, short pulse lengths, frequencies
outside known marine mammal hearing ranges, or some combination of
these factors (U.S. Department of the Navy, 2013). NMFS concurs with
ONR's determination that the sources they have identified here as de
minimis are unlikely to result in take of marine mammals. The following
are some of the de minimis sources which would be used during the
proposed activity: WHOI micromodem, Acoustic Doppler Current Profilers
(ADCPs), ice profilers, and additional sources below 160 dB re 1
[micro]Pa used during towing operations. ADCPs may be used on moorings.
Ice-profilers measure ice properties and roughness. The ADCPs and ice-
profilers would all be above 200 kHz and therefore out of marine mammal
hearing ranges, with the exception of the 75 kHz ADCP which has the
characteristics and de minimis justification listed in table 2. They
may be employed on moorings or AUVs.
A WHOI micromodem will also be employed during the leave behind
period. During the leave behind period, this source is used for very
intermittent communication with vehicles to communicate vehicle status
for safety of navigation purposes. It is treated as de minimis while
employed in this manner (in contrast with the WHOI micromodem usage
described in table 1, which covers the use of the micromodem during
research cruises).
Table 2--Parameters for De minimis Non-Impulsive Acoustic Sources
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Sound
pressure level
Source name Frequency range (dB re 1 Pulse length Duty cycle De minimis justification
(kHz) [micro]Pa at 1 (seconds) (Percent)
m)
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ADCP............................................ >200, 150, or 75 190 <0.001 <0.1 Very low pulse length, narrow
beam, moderate source level.
Nortek Signature 500 kHz Doppler Velocity Log... 500 214 <0.1 <13 Very high frequency.
CTD attached echosounder........................ 5-20 160 0.004 2 Very low source level.
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Note: CTD = conductivity temperature depth.
Drifting Oceanographic Sensors
Observations of ocean-ice interactions require the use of sensors
that are moored and embedded in the ice. Icebreaking would not be
required for these observations, as deployments can be performed in
areas of low ice-coverage or free-floating ice. Sensors are deployed
within a few dozen meters of each other on the same ice floe. Three
types of sensors would be used: (1) autonomous ocean flux buoys; (2)
Integrated Autonomous Drifters; and (3) and ice-tethered profilers. The
autonomous ocean flux buoys measure oceanographic properties just below
the ocean-ice interface with ADCPs and temperature chains to measure
temperature, salinity, and other ocean parameters the top 6 m of the
water column. Integrated Autonomous Drifters have a long temperate
string extending down to 200 m depth and would incorporate
meteorological sensors, and a temperature spring to estimate ice
thickness. The ice-tethered profilers collect information on ocean
temperature, salinity, and velocity down to 250 m depth.
Up to 20 Argo-type autonomous profiling floats may be deployed in
the central Beaufort Sea. Argo floats drift at 1,500 m depth and
collect profiles of temperature and salinity from 2,000 m to the sea
surface once every 10 days.
Moored Oceanographic Sensors
Moored sensors capture a range of ice, ocean, and atmospheric
conditions on a year-round basis via sub-surface moorings anchored to
the seafloor measuring velocity, temperature, and salinity in the upper
500 m of the water column. The moorings also collect high-resolution
acoustic measurements of the ice using the ice profilers described in
table 2. Ice velocity and surface waves would be measured by 500 kHz
multibeam sonars. The moored oceanographic sensors described above use
only de minimis sources and are therefore not anticipated to have the
potential for impacts on marine mammals or their habitat.
On-Ice Measurements
On-ice measurement systems would be used to collect weather data
and include an Autonomous Weather Station and an Ice Mass Balance Buoy.
The Autonomous Weather Station would be deployed on a tripod with
insulated foot platforms that are frozen into the ice and consist of an
anemometer, humidity sensor, and pressure sensor. It also includes an
altimeter that is de minimis due to its very-high frequency (200 kHz).
The Ice
[[Page 46060]]
Mass Balance Buoy is a 6 m sensor string deployed through a 5
centimeter (cm) hole drilled into ice. The string is weighted by a 1
kilogram (kg) lead weight and is supported by a tripod. The buoy
contains a de minimis 200 kHz altimeter and snow depth sensor.
Autonomous Weather Stations and Ice Mass Balance Buoys would be
deployed and drift with the ice, making measurements until their host
ice floes melt, thus destroying the instruments (likely in summer,
roughly 1 year after deployment). After the on-ice instruments are
destroyed they cannot be recovered and would sink to the seafloor as
their host ice floes melted.
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (see Proposed Mitigation
section and Proposed Monitoring and Reporting section).
Description of Marine Mammals in the Area of Specified Activity
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history of the potentially affected species. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs) (https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
Table 3 lists all species or stocks for which take is likely and
proposed to be authorized for this activity and summarizes information
related to the population or stock, including regulatory status under
the MMPA and Endangered Species Act (ESA) and potential biological
removal (PBR), where known. PBR is defined by 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 (as described in NMFS'
SARs). While no serious injury or mortality is anticipated or proposed
to be authorized here, PBR and annual mortality and serious injury (M/
SI) from anthropogenic sources are included here as gross indicators of
the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Alaska SARs. All values presented in table 3 are the most
recent available at the time of publication and are available online
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.
Table 3--Species, Stocks, and the Status of Marine Mammals \1\ with Estimated Take From the Specified Activity
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ESA/MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ SI \4\
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Beluga whale........................ Delphinapterus leucas.. Beaufort Sea........... -, -, N 39,258 (0.229, N/A, UND 104
1992).
Beluga whale........................ Delphinapterus leucas.. Eastern Chukchi........ -, -, N 13,305 (0.51, 8,875, 178 56
2017).
Ringed seal......................... Pusa hispida........... Arctic................. T, D, Y UND \5\ (UND, UND, UND 6,459
2013).
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Note: N/A = not applicable; UND = undetermined.
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
(https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/).
\2\ ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or
designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or
which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is
automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is, in some cases, presented as a minimum value or range.
\5\ A reliable population estimate for the entire stock is not available. Using a sub-sample of data collected from the U.S. portion of the Bering Sea,
an abundance estimate of 171,418 ringed seals has been calculated, but this estimate does not account for availability bias due to seals in the water
or in the shore-fast ice zone at the time of the survey. The actual number of ringed seals in the U.S. portion of the Bering Sea is likely much
higher. Using the Nmin based upon this negatively biased population estimate, the PBR is calculated to be 4,755 seals, although this is also a
negatively biased estimate.
As indicated above, both species (with three managed stocks) in
table 3 temporally and spatially co-occur with the specified activity
to the degree that take is likely to occur. While bowhead whales
(Balaena mysticetus), gray whales (Eschrichtius robustus), narwhals
(Monodon monoceros), bearded seals (Erignathus barbatus), spotted seals
(Phoca largha), and ribbon seals (Histriophoca fasciata) have been
documented in the area, the temporal and/or spatial occurrence of these
species is such that take is not expected to occur, and they are not
discussed further beyond the explanation provided here.
Due to the location of the Study Area (i.e., northern offshore,
deep water), there were no calculated exposures for the bowhead whale,
gray whale, bearded seal, spotted seal, and ribbon seal from
quantitative modeling of acoustic sources. Bowhead and gray whales are
associated with the shallow waters of the continental shelf in the
Beaufort Sea and are unlikely to be exposed to acoustic harassment from
this activity (Carretta et al., 2024; Young et al., 2026). Gray whales
feed primarily in the Beaufort Sea, Chukchi Sea, and Northwestern
Bering Sea during the summer and fall, but migrate south to winter in
Baja California lagoons (Carretta et al., 2024). Gray whales are
primarily bottom feeders (Swartz et al., 2006) in water depths of less
than 60 m (Pike, 1962). Therefore, on the rare occasion that a gray
whale does overwinter in the Beaufort Sea (Stafford et al., 2007), we
would expect an overwintering individual to remain in shallow water
over the continental shelf where it could feed. Spotted seals tend to
prefer pack ice areas with water
[[Page 46061]]
depths less than 200 m during the spring and move to coastal habitats
in the summer and fall, found as far north as 69-72 degrees N (Young et
al., 2026). Although the Study Area includes some waters south of 72
degrees N, the acoustic sources with the potential to result in take of
marine mammals are not found below that latitude and spotted seals are
not expected to be exposed. Ribbon seals are found year-round in the
Bering Sea but may seasonally range into the Chukchi Sea (Young et al.,
2026). The proposed activity occurs primarily in the Beaufort Sea,
outside of the core range of ribbon seals, thus ribbon seals are not
expected to be behaviorally harassed. Narwhals are considered
extralimital in the Study Area and are not expected to be encountered.
In addition, the polar bear (Ursus maritimus) and Pacific walrus
(Odobenus rosmarus) may be found both on sea ice and/or in the water
within the Beaufort Sea and Chukchi Sea; however, both species are
managed by the U.S. Fish and Wildlife Service and are not considered
further in this document.
Beluga Whale
Beluga whales are distributed throughout seasonally ice-covered
arctic and subarctic waters of the Northern Hemisphere (Gurevich, 1980)
and are closely associated with open leads and polynyas in ice-covered
regions (Hazard, 1988). Belugas may be either migratory or residential
(non-migratory), depending on the population. Seasonal distribution is
affected by ice cover, tidal conditions, access to prey, temperature,
and human interaction (Frost et al., 1985; Hauser et al., 2014). Two
stocks, the Beaufort Sea and eastern Chukchi Sea stocks, have the
potential to occur in the location of this proposed activity.
Migratory Biologically Important Areas (BIAs) for belugas in the
eastern Chukchi and Alaskan Beaufort Sea overlap the southern and
western portion of the Study Area (Clarke et al., 2023). A migration
corridor for both stocks of beluga whale includes the eastern Chukchi
Sea through the Beaufort Sea, with the Beaufort Sea stock utilizing the
migratory BIA in April-May and the Eastern Chukchi Sea stock utilizing
portions of the area in November. There are also feeding BIAs for both
stocks throughout the Arctic region (Clarke et al., 2023). During the
winter, they can be found foraging in offshore waters associated with
pack ice. When the sea ice melts in summer, they move to warmer river
estuaries and coastal areas for molting and calving (Young et al.,
2026). Annual migrations can span over thousands of kilometers. The
residential Beaufort Sea populations participate in short distance
movements within their range throughout the year. Based on satellite
tags (Suydam et al., 2001; Hauser et al., 2014), there is some overlap
in distribution with the eastern Chukchi Sea beluga whale stock.
During the winter, eastern Chukchi Sea belugas occur in offshore
waters associated with pack ice. In the spring, they migrate to warmer
coastal estuaries, bays, and rivers where they may molt (Finley, 1982;
Suydam, 2009), give birth to, and care for their calves (Sergeant and
Brodie, 1969). Eastern Chukchi Sea belugas move into coastal areas,
including Kasegaluk Lagoon (outside of the proposed project site), in
late June and animals are sighted in the area until about mid-July
(Frost and Lowry, 1990; Frost et al., 1993). Satellite tags attached to
eastern Chukchi Sea belugas captured in Kasegaluk Lagoon during the
summer showed these whales traveled 1,100 km north of the Alaska
coastline, into the Canadian Beaufort Sea within three months (Suydam
et al., 2001). Satellite telemetry data from 23 whales tagged during
1998-2007 suggest variation in movement patterns for different age and/
or sex classes during July-September (Suydam et al., 2005). Adult males
used deeper waters and remained there for the duration of the summer;
all belugas that moved into the Arctic Ocean (north of 75 degrees N)
were males, and males traveled through 90 percent pack ice cover to
reach deeper waters in the Beaufort Sea and Arctic Ocean (79-80 degrees
N) by late July/early August. Adult and immature female belugas
remained at or near the shelf break in the south through the eastern
Bering Strait into the northern Bering Sea, remaining north of Saint
Lawrence Island over the winter.
Ringed Seal
Ringed seals are the most common pinniped in the Study Area and
have wide distribution in seasonally and permanently ice-covered waters
of the Northern Hemisphere (North Atlantic Marine Mammal Commission,
2004). Throughout their range, ringed seals have an affinity for ice-
covered waters and are well adapted to occupying both shore-fast and
pack ice (Kelly, 1988). Ringed seals can be found further offshore than
other pinnipeds since they can maintain breathing holes in ice
thickness greater than 2 m (Smith and Stirling, 1975). The breathing
holes are maintained by ringed seals using their sharp teeth and claws
found on their fore flippers. They remain in contact with ice most of
the year and use it as a platform for molting in late spring to early
summer, for pupping and nursing in late winter to early spring, and for
resting at other times of the year (Young et al., 2026).
Ringed seals have at least two distinct types of subnivean lairs:
Haulout lairs and birthing lairs (Smith and Stirling, 1975). Haul-out
lairs are typically single-chambered and offer protection from
predators and cold weather. Birthing lairs are larger, multi-chambered
areas that are used for pupping in addition to protection from
predators. Ringed seals pup on both shore-fast ice as well as stable
pack ice. Lentfer (1972) found that ringed seals north of
Utqia[gdot]vik, Alaska, build their subnivean lairs on the pack ice
near pressure ridges. Since subnivean lairs were found north of
Utqia[gdot]vik, Alaska, in pack ice, they are also assumed to be found
within the sea ice in the proposed project site. Ringed seals excavate
subnivean lairs in drifts over their breathing holes in the ice, in
which they rest, give birth, and nurse their pups for 5-9 weeks during
late winter and spring (Chapskii, 1940; McLaren, 1958; Smith and
Stirling, 1975). Ringed seals are born beginning in March but the
majority of births occur in early April. About a month after
parturition, mating begins in late April and early May.
In Alaskan waters, during winter and early spring when sea ice is
at its maximum extent, ringed seals are abundant in the northern Bering
Sea, Norton and Kotzebue Sounds, and throughout the Chukchi and
Beaufort seas (Frost, 1985; Kelly, 1988). Passive acoustic monitoring
of ringed seals from a high frequency recording package deployed at a
depth of 240 m in the Chukchi Sea 120 km north-northwest of
Utqia[gdot]vik, Alaska detected ringed seals in the area between mid-
December and late May over the 4-year study (Jones et al., 2014). In
addition, ringed seals have been observed near and beyond the outer
boundary of the U.S. EEZ (Beland and Ireland, 2010). During the spring
and early summer, ringed seals may migrate north as the ice edge
recedes and spend their summers in the open water period of the
northern Beaufort and Chukchi Seas (Frost, 1985). Foraging-type
movements have been recorded over the continental shelf and north of
the continental shelf waters (Von Duyke et al., 2020). During this
time, sub-adult ringed seals may also occur in the Arctic Ocean Basin
(Hamilton et al., 2015; Hamilton et al., 2017).
With the onset of fall freeze, ringed seal movements become
increasingly
[[Page 46062]]
restricted and seals will either move west and south with the advancing
ice pack with many seals dispersing throughout the Chukchi and Bering
Seas, or remaining in the Beaufort Sea (Crawford et al., 2012; Frost
and Lowry, 1984; Harwood et al., 2012). Kelly et al. (2010) tracked
home ranges for ringed seals in the subnivean period (using shore-fast
ice); the size of the home ranges varied from less than 1 up to 279
km\2\ (median = 0.62 km\2\ for adult males, 0.65 km\2\ for adult
females). Most (94 percent) of the home ranges were less than 3 km\2\
during the subnivean period (Kelly et al., 2010). Near large polynyas,
ringed seals maintain ranges, up to 7,000 km\2\ during winter and 2,100
km\2\ during spring (Born et al., 2004). Some adult ringed seals return
to the same small home ranges they occupied during the previous winter
(Kelly et al., 2010). The size of winter home ranges can vary by up to
a factor of 10 depending on the amount of fast ice; seal movements were
more restricted during winters with extensive fast ice and were much
less restricted where fast ice did not form at high levels (Harwood et
al., 2015).
Of the five recognized subspecies of ringed seals, the Arctic
ringed seal occurs in the Arctic Ocean and Bering Sea and is the only
stock that occurs in U.S. waters. NMFS listed the Arctic ringed seal
subspecies as threatened under the ESA on December 28, 2012 (77 FR
76706), primarily due to anticipated loss of sea ice through the end of
the 21st century.
Critical Habitat
Critical habitat for the ringed seal includes marine waters within
one specific area in the Bering, Chukchi, and Beaufort Seas (87 FR
19232, April 1, 2022). Essential features established by NMFS for
conservation of ringed seals are (1) snow-covered sea ice habitat
suitable for the formation and maintenance of subnivean birth lairs
used for sheltering pups during whelping and nursing, which is defined
as waters 3 m or more in depth (relative to Mean Lower Low Water
(MLLW)) containing areas of seasonal land-fast (shore-fast) ice or
dense, stable pack ice, that have undergone deformation and contain
snowdrifts of sufficient depth to form and maintain birth lairs
(typically at least 54 cm (21.3 in) deep); (2) sea ice habitat suitable
as a platform for basking and molting, which is defined as areas
containing sea ice of 15 percent or more concentration in waters 3 m
(9.8 ft) or more in depth (relative to MLLW); and (3) primary prey
resources to support Arctic ringed seals, which are defined to be
small, often schooling, fishes, in particular Arctic cod (Boreogadus
saida), saffron cod (Eleginus gracilis), and rainbow smelt (Osmerus
dentex); and small crustaceans, in particular, shrimps and amphipods.
The Study Area does not overlap with ringed seal critical habitat
(87 FR 19232, April 1, 2022); however, as stated in NMFS' final rule
for the Designation of Critical Habitat for the Arctic Subspecies of
the Ringed Seal (87 FR 19232, April 1, 2022), the area excluded from
the critical habitat contains one or more of the essential features of
the Arctic ringed seal's critical habitat, therefore, even though this
area is excluded from critical habitat designation, habitat with the
physical and biological features essential for ringed seal conservation
is still available to the species, although data are limited to inform
NMFS' assessment of the relative value of this area to the conservation
of the species; however, as described later and in more detail in the
Potential Effects of Specified Activity on Marine Mammals and their
Habitat section, we expect minimal impacts to marine mammal habitat as
a result of ONR's ARA, including impacts to ringed seal sea ice habitat
suitable as a platform for basking and molting and impacts on prey
availability.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007) and Southall et al. (2019) recommended that marine mammals be
divided into hearing groups based on directly measured (behavioral or
auditory evoked potential techniques) or estimated hearing ranges
(behavioral response data, anatomical modeling, etc.). Generalized
hearing ranges were chosen based on the approximately 65 dB threshold
from composite audiograms, previous analyses in NMFS (2018), and/or
data from Southall et al. (2007) and Southall et al. (2019). We note
that the names of two hearing groups and the generalized hearing ranges
of all marine mammal hearing groups have been recently updated (NMFS,
2024) as reflected below in table 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36 kHz.
whales).
High-frequency (HF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
Very High-frequency (VHF) cetaceans 200 Hz to 165 kHz.
(true porpoises, Kogia, river
dolphins, Cephalorhynchid,
Lagenorhynchus cruciger & L.
australis).
Phocid pinnipeds (PW) (underwater) 40 Hz to 90 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 68 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges may not be as broad. Generalized hearing range
chosen based on approximately 65 dB threshold from composite
audiogram, previous analysis in NMFS (2018), and/or data from Southall
et al. (2007) and Southall et al. (2019). Additionally, animals are
able to detect very loud sounds above and below that ``generalized''
hearing range.
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activity on Marine Mammals and Their
Habitat
This section discusses how components of the specified activity may
impact marine mammals and their habitat. The Estimated Take of Marine
Mammals section includes a quantitative analysis of the number of
individuals that are expected to be taken by this activity. The
Negligible Impact
[[Page 46063]]
Analysis and Determination section considers the content of this
section, the Estimated Take of Marine Mammals section, and the Proposed
Mitigation section to draw conclusions regarding the likely impacts of
these activities on the reproductive success or survivorship of
individuals and whether those impacts are reasonably expected to, or
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival.
ONR has requested authorization to take marine mammals incidental
to ARA in the Study Area. ONR analyzed potential impacts to marine
mammals from acoustic sources in the application. Acoustic effects on
marine mammals during the proposed activities can occur from active
acoustics and icebreaking. The effects of underwater noise from ONR's
proposed activities have the potential to result in take by Level B
harassment of beluga whales and ringed seals in the Study Area.
Potential Effects of Underwater Sound on Marine Mammals
The marine soundscape is composed of both ambient and anthropogenic
sounds. Ambient sound is defined as the all-encompassing sound in a
given place and is usually a composite of sound from many sources both
near and far (American National Standards Institute (ANSI), 1995). The
sound level of an area is defined by the total acoustical energy being
generated by known and unknown sources, which may include physical
(e.g., waves, wind, precipitation, earthquakes, ice, atmospheric
sound), biological (e.g., sounds produced by marine mammals, fish, and
invertebrates), and anthropogenic sound (e.g., vessels, dredging,
aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor and is frequency dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al., 1995). The result is that,
depending on the source type and its intensity, sound from the
specified activity may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
Anthropogenic sounds cover a broad range of frequencies and sound
levels and can have a range of highly variable impacts on marine life,
from none or minor to potentially severe responses, depending on
received levels, duration of exposure, behavioral context, and various
other factors. The potential effects of underwater sound from active
acoustic sources can possibly result in one or more of the following:
temporary or permanent hearing impairment, other auditory injury, non-
auditory physical or physiological effects, behavioral disturbance,
stress, and masking (Richardson et al., 1995; Gordon et al., 2003;
G[ouml]tz et al., 2009; Nowacek et al., 2007; Southall et al., 2007;
Southall et al., 2019; Erbe et al., 2025). The degree of effect is
intrinsically related to the signal characteristics, received level,
distance from the source, and duration of the sound exposure. In
general, sudden, high-level sounds can cause auditory injury, as can
longer exposures to lower-level sounds. Temporary or permanent loss of
hearing can occur after exposure to noise and occurs almost exclusively
for noise within an animal's hearing range.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur, in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First is the area within which the acoustic signal would be
audible (potentially perceived) to the animal, but not strong enough to
elicit any overt behavioral or physiological response. The next zone
corresponds with the area where the signal is audible to the animal and
of sufficient intensity to elicit behavioral or physiological
responsiveness. Third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory systems. Overlaying these zones
to a certain extent is the area within which masking (i.e., when a
sound interferes with or masks the ability of an animal to detect a
signal of interest that is above the absolute hearing threshold) may
occur; the masking zone may be highly variable in size (see Masking
section).
Underwater sounds fall into one of two general sound types:
impulsive and non-impulsive (defined in the following paragraphs). The
distinction between these two sound types is important because they
have differing potential to cause physical effects, particularly with
regard to hearing (e.g., Ward (1997) in Southall et al. (2007)). Please
see Southall et al. (2007) for an in-depth discussion of these
concepts.
Impulsive sound sources (e.g., explosions, gunshots, sonic booms,
impact pile driving) produce signals that are brief (typically
considered to be less than one second), broadband, atonal transients
(ANSI, 1986; ANSI, 2005; Harris, 1998; National Institute for
Occupational Safety and Health (NIOSH), 1998) and occur either as
isolated events or repeated in some succession. Non-impulsive sounds
can be tonal, narrowband, or broadband, brief or prolonged, and may be
either continuous or non-continuous (ANSI, 1995; NIOSH, 1998). Some of
these non-impulsive sounds can be transient signals of short duration
but without the essential properties of pulses (e.g., rapid rise time).
Examples of non-impulsive sounds include those produced by vessels,
aircraft, machinery operations such as drilling or dredging, vibratory
pile driving, and active acoustic sources (such as those proposed for
use by ONR as part of the proposed activities).
The likely or possible impacts of ONR's proposed activity on marine
mammals involve both non-acoustic and acoustic stressors. Potential
non-acoustic stressors could result from the physical presence of
vessels, equipment, and personnel (e.g., icebreaking impacts, vessel
and in-water vehicle strike, and seafloor disturbance); however, any
impacts to marine mammals are expected to primarily be acoustic in
nature (e.g., non-impulsive acoustic sources, noise from icebreaking
vessel (``icebreaking noise''), and vessel noise).
Hearing Threshold Shift
NMFS defines a noise-induced threshold shift (TS) as a change,
usually an increase, in the threshold of audibility at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS, 2018; NMFS, 2024). The
amount of TS is customarily expressed in dB. A TS can be permanent or
temporary. As described in NMFS (2018) and NMFS (2024), there are
numerous factors to consider when examining the consequence of TS,
including, but not limited to, the signal temporal pattern (e.g.,
impulsive or non-impulsive), likelihood an individual would be exposed
for a long enough duration or to a high enough level to induce a TS,
the magnitude of the TS, time to recovery (seconds to minutes or hours
to days), the frequency range of the exposure (i.e., spectral content),
the hearing frequency range of the exposed
[[Page 46064]]
species relative to the signal's frequency spectrum (i.e., how animal
uses sound within the frequency band of the signal) (e.g., Kastelein et
al., 2014), and the overlap between the animal and the source (e.g.,
spatial, temporal, and spectral).
Auditory Injury (AUD INJ) and Permanent Threshold Shift (PTS)
NMFS defines AUD INJ as damage to the inner ear that can result in
destruction of tissue, such as the loss of cochlear neuron synapses or
auditory neuropathy (Finneran, 2024; Houser, 2021). AUD INJ may or may
not result in PTS, which NMFS defines as a permanent, irreversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS, 2024). PTS does not generally affect more than a
limited frequency range, and an animal that has incurred PTS has
incurred some level of hearing loss at the relevant frequencies;
typically, animals with PTS are not functionally deaf (Au and Hastings,
2008; Finneran, 2016). Available data from humans and other terrestrial
mammals indicate that a 40-dB threshold shift approximates PTS onset
(see Ahroon et al., 1996; Henderson et al., 2008; Kryter et al., 1966;
Miller, 1974; Ward, 1960; Ward et al., 1958; Ward et al., 1959). AUD
INJ criteria for marine mammals are estimates; with the exception of a
single study unintentionally inducing PTS in a harbor seal (Phoca
vitulina) (Reichmuth et al., 2019), there are no empirical data
measuring PTS in marine mammals largely due to the fact that, for
various ethical reasons, experiments involving anthropogenic noise
exposure at levels inducing AUD INJ are not typically pursued or
authorized (NMFS, 2024).
Temporary Threshold Shift (TTS)
TTS is a temporary, reversible increase in the threshold of
audibility at a specified frequency or portion of an individual's
hearing range above a previously established reference level (NMFS,
2024), and is not considered an AUD INJ. Based on data from marine
mammal TTS measurements (Southall et al., 2007; Southall et al., 2019),
a TTS of 6 dB is considered the minimum TS clearly larger than any day-
to-day or session-to-session variation in a subject's normal hearing
ability (Finneran et al., 2000; Finneran et al., 2002; Schlundt et al.,
2000). As described in Finneran (2015), marine mammal studies have
shown the amount of TTS increases with cumulative sound exposure level
(SEL24h) in an accelerating fashion: at low exposures with
lower SEL24h, the amount of TTS is typically small and the
growth curves have shallow slopes. At exposures with higher
SEL24h, the growth curves become steeper and approach linear
relationships with the noise SEL.
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 the Masking section). For example, a
marine mammal may be able to readily compensate for a brief, relatively
small amount of TTS in a non-critical frequency range that takes place
during a time where ambient noise is lower and there are not as many
competing sounds present. Alternatively, a larger amount and longer
duration of TTS sustained during time when communication is critical
for successful mother/calf interactions could have more serious impacts
if it were in the same frequency band as the necessary vocalizations
and of a severity that impeded communication. The fact that animals
exposed to high levels of sound that would be expected to result in
this physiological response would also be expected to have behavioral
responses of a comparatively more severe or sustained nature is
potentially more significant than the simple existence of a TTS.
However, it is important to note that TTS could occur due to longer
exposures to sound at lower levels so that a behavioral response may
not be elicited.
Depending on the degree and frequency range, the effects of AUD INJ
on an animal could also range in severity, although it is considered
generally more serious than TTS because it is a permanent condition
(Reichmuth et al., 2019). Of note, reduced hearing sensitivity as a
simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without some cost to the animal.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015), Southall et al. (2019), and NMFS (2024)
for summaries). TTS is the mildest form of hearing impairment that can
occur during exposure to sound. While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of more severe TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. For
cetaceans, published data on the onset of TTS are limited to captive
bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise
(Phocoena phocoena), and Yangtze finless porpoise (Neophocoena
asiaeorientalis) (Southall et al., 2019). For pinnipeds in water,
measurements of TTS are limited to harbor seals, elephant seals
(Mirounga angustirostris), bearded seals, and California sea lions
(Zalophus californianus) (Kastak et al., 2007; Kastelein et al., 2019a;
Kastelein et al., 2019c; Kastelein et al., 2021; Kastelein et al.,
2022a; Kastelein et al., 2022b; Reichmuth et al., 2019; Sills et al.,
2020). TTS was not observed in spotted and ringed seals exposed to
single airgun impulse sounds at levels matching previous predictions of
TTS onset (Reichmuth et al., 2016). These studies examine hearing
thresholds measured in marine mammals before and after exposure to
intense or long-duration sound exposures. The difference between the
pre-exposure and post-exposure thresholds can be used to determine the
amount of threshold shift at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2019a; Kastelein et al., 2019b), Note that in
general, harbor seals and harbor porpoises have a lower TTS onset than
other measured pinniped or cetacean species (Finneran, 2015; Southall
et al., 2019). In addition, TTS can accumulate across multiple
exposures, but the resulting TTS will be less than the TTS from a
single, continuous exposure with the same SEL24h (Finneran
et al., 2010; Kastelein et al., 2014; Mooney et al., 2009). This means
that TTS predictions based on the total, cumulative SEL24h
will overestimate the amount of TTS from
[[Page 46065]]
intermittent exposures, such as sonars and impulsive sources.
Nachtigall et al. (2018) describe measurements of hearing sensitivity
of multiple odontocete species (bottlenose dolphin, harbor porpoise,
beluga, and false killer whale (Pseudorca crassidens)) 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. Another study showed that echolocating animals
(including odontocetes) might have anatomical specializations that
might allow for conditioned hearing reduction and filtering of low-
frequency ambient noise, including increased stiffness and control of
middle ear structures and placement of inner ear structures (Ketten et
al., 2021). Data available on noise-induced hearing loss for mysticetes
are currently lacking. Additionally, the existing marine mammal TTS
data come from a limited number of individuals within these species.
Relationships between TTS and AUD INJ thresholds have not been
studied in marine mammals, and there are no PTS data for cetaceans, but
such relationships are assumed to be similar to those in humans and
other terrestrial mammals. AUD INJ typically occurs at exposure levels
at least several decibels above that inducing mild TTS (e.g., a 40-dB
threshold shift approximates PTS onset (Kryter et al., 1966; Miller,
1974), while a 6-dB threshold shift approximates TTS onset (Southall et
al., 2007; Southall et al., 2019)). Based on data from terrestrial
mammals, a precautionary assumption is that the AUD INJ thresholds for
impulsive sounds (such as impact pile driving) are at least 6 dB higher
than the TTS threshold on a peak sound pressure level basis and AUD INJ
SEL24h thresholds are 15 to 20 dB higher than TTS
SEL24h thresholds (Southall et al., 2007; Southall et al.,
2019). Given the higher level of sound or longer exposure duration
necessary to cause AUD INJ as compared with TTS, it is considerably
less likely that AUD INJ could occur.
Behavioral Responses
Exposure to noise also has the potential to behaviorally disturb
marine mammals to a level that qualifies as harassment under the MMPA.
Behavioral responses to sound are highly variable and context-specific
(Nowacek et al., 2007; Southall et al., 2007; Southall et al., 2019).
Many different variables can influence an animal's perception of and
response to (nature and magnitude) an acoustic event. An animal's prior
experience with a sound or sound source affects whether it is less
likely (habituation, self-mitigation) or more likely (sensitization) to
respond to certain sounds in the future (animals can also be innately
predisposed to respond to certain sounds in certain ways) (Finneran,
2018; Finneran et al., 2024; Nachtigall and Supin, 2013; Nachtigall and
Supin, 2014; Nachtigall and Supin, 2015; Nachtigall et al., 2016a;
Nachtigall et al., 2016b; Southall et al., 2007; Southall et al.,
2016). Related to the sound itself, the perceived proximity of the
sound, bearing of the sound (approaching vs. retreating), the
similarity of a sound to biologically relevant sounds in the animal's
environment (i.e., calls of predators, prey, or conspecifics),
familiarity of the sound, and navigational constraints may affect the
way an animal responds to the sound (DeRuiter et al., 2013a; Ellison et
al., 2012; Southall et al., 2007; Southall et al., 2021; Wartzok et
al., 2003). Individuals (of different age, gender, reproductive status,
etc.) among most populations will have variable hearing capabilities,
and differing behavioral sensitivities to sounds that will be affected
by prior conditioning, experience, and current activities of those
individuals. Southall et al. (2007) and Southall et al. (2021) have
developed and subsequently refined methods developed to categorize and
assess the severity of acute behavioral responses, considering impacts
to individuals that may consequently impact populations. Often,
specific acoustic features of the sound and contextual variables (i.e.,
proximity, duration, or recurrence of the sound or the current behavior
that the marine mammal is engaged in or its prior experience), as well
as entirely separate factors such as the physical presence of a nearby
vessel, may be more relevant to the animal's response than the received
level alone.
Studies by DeRuiter et al. (2013a) indicate that variability of
responses to acoustic stimuli depends not only on the species receiving
the sound and the sound source, but also on the social, behavioral, or
environmental contexts of exposure. Another study by DeRuiter et al.
(2013b) examined behavioral responses of goose-beaked whales to MF
sonar and found that whales responded strongly at low received levels
(89-127 dB re 1 [micro]Pa) by ceasing normal fluking and echolocation,
swimming rapidly away, and extending both dive duration and subsequent
non-foraging intervals when 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 [micro]Pa) from distant sonar
exercises 118 km away did not elicit such responses, suggesting that
context may moderate responses.
Ellison et al. (2012) outlined an approach to assessing the effects
of sound on marine mammals that incorporates contextual-based factors.
The authors recommend considering not just the received level of sound,
but also the activity the animal is engaged in at the time the sound is
received, the nature and novelty of the sound (i.e., whether this is 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.
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
[[Page 46066]]
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 et
al. (1995). More recent reviews (Nowacek et al., 2007; DeRuiter et al.,
2013a; DeRuiter et al., 2013b; Ellison et al., 2012; Gomez et al.,
2016) address studies conducted since 1995 and focused on observations
where the received sound level of the exposed marine mammal(s) was
known or could be estimated. Gomez et al. (2016) conducted a review of
the literature considering the contextual information of exposure in
addition to received level and found that higher received levels were
not always associated with more severe behavioral responses and vice
versa. Southall et al. (2016) states that results demonstrate that some
individuals of different species display clear yet varied responses,
some of which have negative implications, while others appear to
tolerate high levels, and that responses may not be fully predictable
with simple acoustic exposure metrics (e.g., received sound level).
Rather, the authors state that differences among species and
individuals along with contextual aspects of exposure (e.g., behavioral
state) appear to affect response probability (Southall et al., 2019).
The following parts provide examples of behavioral responses to
stressors that provide an idea of the variability in responses that
would be expected given the differential sensitivities of marine mammal
species to sound and the wide range of potential acoustic sources to
which a marine mammal may be exposed. Behavioral responses that could
occur for a given sound exposure should be determined from the
literature that is available for each species or extrapolated from
closely related species when no information exists, along with
contextual factors.
For non-impulsive sounds (i.e., similar to the sources used during
the proposed specified activity), data suggest that exposures of
pinnipeds to received levels between 90 and 140 dB re 1 [mu]Pa do not
elicit strong behavioral responses; no data were available for
exposures at higher received levels for Southall et al. (2007) to
include in the severity scale analysis. Reactions of harbor seals were
the only available data for which the responses could be ranked on the
severity scale. For reactions that were recorded, the majority (17 of
18 individuals/groups) were ranked on the severity scale as a 4
(defined as moderate change in movement, brief shift in group
distribution, or moderate change in vocal behavior) or lower; the
remaining response was ranked as a 6 (defined as minor or moderate
avoidance of the sound source). Additional data on hooded seals
(Cystophora cristata) indicate avoidance responses to signals above
160-170 dB re 1 [mu]Pa (Kvadsheim et al., 2010), and data on gray seals
(Halichoerus grypus) and harbor seals indicate avoidance response at
received levels of 135-144 dB re 1 [mu]Pa (G[ouml]tz et al., 2010). In
each instance where food was available, which provided the seals
motivation to remain near the source, habituation to the signals
occurred rapidly. In the same study, it was noted that habituation was
not apparent in wild seals where no food source was available
(G[ouml]tz et al., 2010). This implies that the motivation of the
animal is necessary to consider in determining the potential for a
reaction. In one study that aimed to investigate the under-ice
movements and sensory cues associated with under-ice navigation of ice
seals, acoustic transmitters (60-69 kHz at 159 dB re 1 [mu]Pa at 1 m)
were attached to ringed seals (Wartzok et al., 1992a; Wartzok et al.,
1992b). An acoustic tracking system then was installed in the ice to
receive the acoustic signals and provide real-time tracking of ice seal
movements. Although the frequencies used in this study are at the upper
limit of ringed seal hearing, the ringed seals appeared unaffected by
the acoustic transmissions, as they were able to maintain normal
behaviors (e.g., finding breathing holes).
Responses Due to Icebreaking Noise
Ringed seals on pack ice showed various behaviors when approached
by an icebreaking vessel. A majority of seals dove underwater when the
ship was within 0.93 km while others remained on the ice. However, as
icebreaking vessels came closer to the seals, most dove underwater.
Ringed seals have also been observed foraging in the wake of an
icebreaking vessel (Richardson et al., 1995) and may have
preferentially established breathing holes in the ship tracks after the
icebreaker moved through the area. Previous observations and studies
using icebreaking ships provide a greater understanding in how seal
behavior may be affected by a vessel transiting through the area.
Adult ringed seals spend up to 20 percent of the time in subnivean
lairs during the winter season (Kelly et al., 2010). Ringed seal pups
spend about 50 percent of their time in the lair during the nursing
period (Lydersen and Hammill, 1993). During the warm season ringed
seals haul out on the ice. In a study of ringed seal haul out activity
by Born et al. (2002), ringed seals spent 25-57 percent of their time
hauled out in June, which is during their molting season. Ringed seal
lairs are typically used by individual seals (haulout lairs) or by a
mother with a pup (birthing lairs); large lairs used by many seals for
hauling out are rare (Smith and Stirling, 1975). If the non-impulsive
acoustic transmissions are heard and are perceived as a threat, ringed
seals within subnivean lairs could react to the sound in a similar
fashion to their reaction to other threats, such as polar bears (their
primary predators), although the type of sound would be novel to them.
Responses of ringed seals to a variety of human-induced sounds (e.g.,
helicopter noise, snowmobiles, dogs, people, and seismic activity) have
been variable; some seals entered the water and some seals remained in
the lair. However, in all instances in which observed seals departed
lairs in response to noise disturbance, they subsequently reoccupied
the lair (Kelly, 1988).
Ringed seal mothers have a strong bond with their pups and may
physically move their pups from the birth lair to an alternate lair to
avoid predation, sometimes risking their lives to defend their pups
from potential predators. If a ringed seal mother perceives the
proposed acoustic sources as a threat, the network of multiple birth
and haulout lairs allows the mother and pup to move to a new lair
(Smith and Stirling, 1975; Smith and Hammill, 1981). The acoustic
sources proposed for use during this activity are not likely to impede
a ringed seal from finding a breathing hole or lair, as captive seals
have been found to primarily use vision to locate breathing holes and
no effect to ringed seal vision would occur from the acoustic
disturbance (Elsner et al., 1989; Wartzok et al., 1992). It is
anticipated that a ringed seal would be able to relocate to a different
breathing hole relatively easily without impacting their normal
behavior patterns.
Masking
Sound can disrupt behavior through masking, or interfering with, an
animal's ability to detect, recognize, interpret, or discriminate
between acoustic signals of interest (e.g., those used for
intraspecific communication and social interactions,
[[Page 46067]]
prey detection, predator avoidance, or navigation) (Branstetter and
Sills, 2022; Clark et al., 2009; Erbe and Farmer, 2000; Erbe et al.,
2016; Richardson et al., 1995; Tyack, 2000). Masking occurs when the
receipt of a sound is interfered with by another coincident sound at
similar frequencies and at similar or higher intensity and may occur
whether the coincident sound is natural (e.g., snapping shrimp, wind,
waves, precipitation) or anthropogenic (e.g., shipping, sonar, seismic
exploration) in origin.
The ability of a noise source to mask biologically important sounds
depends on the characteristics of both the noise source and the signal
of interest (e.g., signal-to-noise ratio, temporal variability,
direction), in relation to each other and to an animal's hearing
abilities (e.g., sensitivity, frequency range, critical ratios,
frequency discrimination, directional discrimination, age, or TTS
hearing loss), and existing ambient noise and propagation conditions.
Masking these acoustic signals can disturb the behavior of individual
animals, groups of animals, or entire populations. Masking can lead to
behavioral changes including vocal changes (e.g., Lombard effect,
increasing amplitude, or changing frequency), cessation of foraging,
and leaving an area, to both signalers and receivers, in an attempt to
compensate for noise levels (Erbe et al., 2016).
Most research on auditory masking is focused on energetic masking,
or the ability of the receiver (i.e., listener) to detect a signal in
noise. However, from a fitness perspective, both signal detection and
signal interpretation are necessary for success. This type of masking
is called informational masking and occurs when a signal is detected by
an animal but the meaning of that signal has been lost. Few data exist
on informational masking in marine mammals but studies have shown that
some recognition of predator cues might be missed by species that are
preyed upon by killer whales if killer whale vocalizations are masked
(Cur[eacute] et al., 2015; Cur[eacute] et al., 2016; Deecke et al.,
2002; Isojunno et al., 2016; Visser et al., 2016). von Benda-Beckmann
et al. (2021) modeled the effect of pulsed and continuous active sonars
on sperm whale (Physeter macrocephalus) echolocation and found that
sonar sounds could reduce the ability of sperm whales to find prey
under certain conditions.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (i.e., masking) sound is human-made, it may be considered
harassment when disrupting natural behavioral patterns to the point
where the behavior is abandoned or significantly altered. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which only occurs during the sound exposure.
Because masking (without resulting in TS) is not associated with
abnormal physiological function, it is not considered a physiological
effect, but rather a potential behavioral effect (though not
necessarily one that would be associated with harassment).
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., Di
Iorio and Clark, 2010; Foote et al., 2004; Holt et al., 2009; Miller et
al., 2000; Parks et al., 2007). Masking can be reduced in situations
where the signal and noise come from different directions (Richardson
et al., 1995), through amplitude modulation of the signal, or through
other compensatory behaviors (Houser and Moore, 2014). Masking can be
tested directly in captive species, but in wild populations it must be
either modeled or inferred from evidence of masking compensation. There
are few studies addressing real-world masking sounds likely to be
experienced by marine mammals in the wild (e.g., Branstetter et al.,
2024; Branstetter and Sills, 2022, Cholewiak et al., 2018).
Marine mammals within or near the Study Area may be exposed to
anthropogenic noise which may be a source of masking. Vocalization
changes may result from a need to compete with an increase in
background noise and include increasing the source level, modifying the
frequency, increasing the call repetition rate of vocalizations, or
ceasing to vocalize in the presence of increased noise (Hotchkin and
Parks, 2013). For example, in response to loud noise, beluga whales may
shift the frequency of their echolocation clicks to prevent masking by
anthropogenic noise (Eickmeier and Vallarta, 2023).
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources such as vibratory pile driving.
Energy distribution of pile driving covers a broad frequency spectrum,
and sound from pile driving would be within the audible range of
pinnipeds and cetaceans present in the Study Area. While icebreaking
during ONR's proposed activity may mask some acoustic signals that are
relevant to the daily behavior of marine mammals, the short-term
duration (up to 8 days) and limited areas affected make it very
unlikely that the fitness of individual marine mammals would be
impacted.
Stress Response
Physiological stress is a natural and adaptive process that helps
an animal survive changing conditions. When an animal perceives a
potential threat, whether or not the stimulus actually poses a threat,
a stress response is triggered (Moberg, 2000; Sapolsky, 2005; Selye,
1950). Once an animal's central nervous system perceives a threat, it
mounts a biological response or defense that consists of a combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses.
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and distress is the biotic cost
of the response. During a stress response, an animal uses glycogen
stores that can be quickly replenished once the stress is alleviated.
In such circumstances, the cost of the stress response would not pose
serious fitness consequences. However, when an animal does not have
sufficient energy reserves to satisfy the energetic costs of a stress
response, energy resources must be diverted from other biotic
functions. For example, when a stress response diverts energy away from
growth in young animals, those animals may experience stunted growth.
When a stress response diverts energy from a fetus, an animal's
reproductive success and its fitness will suffer. In these cases, the
animals will have entered a pre-pathological or pathological state
which is called ``distress'' (Selye, 1950) or ``allostatic loading''
(McEwen and Wingfield, 2003). This pathological state of distress will
last until the animal replenishes its energetic reserves sufficiently
to restore normal function.
According to Moberg (2000), in the case of many stressors, an
animal's first and sometimes most economical (in
[[Page 46068]]
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 hypothalamus-pituitary-adrenal
(HPA) system (also known as the HPA axis in mammals or the
hypothalamus-pituitary-interrenal axis in fish and some reptiles).
Unlike stress responses associated with the autonomic nervous system,
virtually all neuro-endocrine functions that are affected by stress,
including immune competence, reproduction, metabolism, and behavior,
are regulated by pituitary hormones. Stress-induced changes in the
secretion of pituitary hormones have been implicated in failed
reproduction (Moberg, 1987; Rivier and Rivest, 1991), altered
metabolism (Elsasser et al., 2000), reduced immune competence (Blecha,
2000), and behavioral disturbance (Blecha, 2000, Moberg, 1987).
Increases in the circulation of glucocorticosteroids (cortisol,
corticosterone, and aldosterone in marine mammals; see Romano et al.
(2004)) have been equated with stress for many years.
Marine mammals naturally experience stressors within their
environment and as part of their life histories. Changing weather and
ocean conditions, exposure to disease and naturally occurring toxins,
lack of prey availability, and interactions with predators all
contribute to the stress a marine mammal experiences (Atkinson et al.,
2015). Breeding cycles, periods of fasting, social interactions with
members of the same species, and molting (for pinnipeds) are also
stressors, although they are natural components of an animal's life
history. Anthropogenic activities have the potential to provide
additional stressors beyond those that occur naturally (e.g., fishery
interactions, pollution, tourism, ocean noise) (Fair et al., 2014;
Meissner et al., 2015; Rolland et al., 2012).
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005; Reneerkens et al., 2002;
Thompson and Hamer, 2000). Relatively little information exists on the
linkage between anthropogenic sound exposure and stress in marine
mammals, and even less information exists on the ultimate consequences
of sound-induced stress responses (either acute or chronic). The
ability to make predictions from stress hormones about impacts on
individuals and populations exposed to various forms of natural and
anthropogenic stressors relies on understanding the linkages between
changes in stress hormones and resulting physiological impacts.
Currently, the sound characteristics that correlate with specific
stress responses in marine mammals are poorly understood, as are the
ultimate consequences of these changes. Several research efforts have
improved the understanding of, and the ability to predict, how
stressors ultimately affect marine mammal populations (e.g., King et
al., 2015; New et al., 2013; Pirotta et al., 2015; Pirotta et al.,
2022). This includes determining how and to what degree various types
of anthropogenic sound cause stress in marine mammals and understanding
what factors may mitigate those physiological stress responses. Factors
potentially affecting an animal's response to a stressor include life
history, sex, age, reproductive status, overall physiological and
behavioral adaptability, and whether they are na[iuml]ve or experienced
with the sound (e.g., prior experience with a stressor may result in a
reduced response due to habituation) (Finneran and Branstetter, 2013;
St. Aubin and Dierauf, 2001). Because there are many unknowns regarding
the occurrence of acoustically induced stress responses in marine
mammals, any physiological response (e.g., hearing loss or injury) or
significant behavioral response is assumed to be associated with a
stress response. Any animal experiencing TTS would likely also
experience stress responses, however, distress is an unlikely result of
the proposed activity based on observations of marine mammals during
previous, similar projects in the region.
Potential Effects on Marine Mammal Habitat
ONR's proposed activities could have localized, temporary impacts
on marine mammal habitat, including prey, by increasing in-water SPLs.
Increased noise levels may affect acoustic habitat and adversely affect
marine mammal prey within the Study Area.
Potential Effects on Prey
Marine mammal species in the Study Area feed on marine
invertebrates and fish. Although most species of marine invertebrates
are found within the benthic zone, they can be found in all zones
(sympagic (within the sea ice), pelagic (open ocean), or benthic
(bottom dwelling)) of the Beaufort Sea (Josefson et al., 2013). The
diverse range of species include oysters, crabs, worms, ghost shrimp,
snails, sponges, sea fans, isopods, and stony corals (Chess, 1997;
Dugan et al., 2000; Proctor, 1981).
Hearing capabilities of invertebrates are largely unknown (Lovell
et al., 2005; Popper and Schilt, 2008). Outside of studies conducted to
test the sensitivity of invertebrates to vibrations, very little is
known about the effects of anthropogenic underwater noise on
invertebrates (Edmonds et al., 2016). While data are limited, research
suggests that some of the major cephalopods and decapods may have
limited hearing capabilities (Hanlon, 1987; Offutt, 1970) and may hear
only low-frequency (less than 1 kHz) sources (Offutt, 1970), which is
most likely within the frequency band of biological signals (Hill,
2009). Acoustic signals produced by crustaceans range from low
frequency rumbles (20-60 Hz) to high frequency signals (20-55 kHz)
(Henninger and Watson III, 2005; Patek and Caldwell, 2006; Staaterman
et al., 2011). Aquatic invertebrates that can sense local water
movements with ciliated cells include cnidarians, flatworms, segmented
worms, urochordates (tunicates), mollusks, and arthropods (Budelmann,
1992a; Budelmann, 1992b; Popper et al., 2001). Some aquatic
invertebrates have specialized organs called statocysts for
determination of equilibrium and, in some cases, linear or angular
acceleration. Statocysts allow an animal to sense movement and may
enable some species, such as cephalopods and crustaceans, to be
sensitive to water particle movements associated with sound (Goodall et
al., 1990; Hu et al., 2009; Kaifu et al., 2008; Montgomery et al.,
2006; Popper et al., 2001; Roberts and Breithaupt, 2016; Salmon, 1971).
Because any acoustic sensory capabilities, if present at all, are
limited
[[Page 46069]]
to detecting water motion, and water particle motion near a sound
source falls off rapidly with distance, aquatic invertebrates are
probably limited to detecting nearby sound sources rather than sound
caused by pressure waves from distant sources.
Studies of sound energy effects on invertebrates are few and
identify only behavioral responses. Non-auditory injury, AUD INJ, TTS,
and masking studies have not been conducted for invertebrates. Both
behavioral and auditory brainstem response studies suggest that
crustaceans may sense frequencies up to 3 kHz, but best sensitivity is
likely below 200 Hz (Goodall et al., 1990; Lovell et al., 2005; Lovell
et al., 2006). Most cephalopods likely sense low-frequency sound below
1 kHz, with best sensitivities at lower frequencies (Budelmann, 2010;
Mooney et al., 2010; Offutt, 1970). A few cephalopods may sense higher
frequencies up to 1,500 Hz (Hu et al., 2009).
Although acoustic sources used during the proposed activities may
briefly impact individuals, intermittent exposures to non-impulsive
acoustic sources are not expected to impact survival, growth,
recruitment, or reproduction of widespread marine invertebrate
populations.
The fish species located in the Study Area include those that are
closely associated with the deep ocean habitat of the Beaufort Sea.
Nearly 250 marine fish species have been described in the Arctic,
excluding the larger parts of the sub-Arctic Bering, Barents, and
Norwegian Seas (Mecklenburg et al., 2011). However, only about 30 are
known to occur in the Arctic waters of the Beaufort Sea (Christiansen
and Reist, 2013). Largely because of the difficulty of sampling in
remote, ice-covered seas, many high-Arctic fish species are known only
from rare or geographically patchy records (Mecklenburg et al., 2011).
Aquatic systems of the Arctic undergo extended seasonal periods of ice
cover and other harsh environmental conditions. Fish inhabiting such
systems must be biologically and ecologically adapted to surviving such
conditions. Important environmental factors that Arctic fish must
contend with include reduced light, seasonal darkness, ice cover, low
biodiversity, and low seasonal productivity.
All fish have two sensory systems to detect sound in the water: the
inner ear, which functions very much like the inner ear in other
vertebrates, and the lateral line, which consists of a series of
receptors along the fish's body (Popper and Fay, 2010; Popper et al.,
2014). The inner ear generally detects relatively higher-frequency
sounds, while the lateral line detects water motion at low frequencies
(below a few hundred Hz) (Hastings and Popper, 2005). Lateral line
receptors respond to the relative motion between the body surface and
surrounding water; this relative motion; however, only takes place very
close to sound sources, and most fish are unable to detect this motion
at more than one to two body lengths distance away (Popper et al.,
2014). Although hearing capability data only exist for fewer than 100
of the approximately 32,000 fish species known to exist, current data
suggest that most species of fish detect sounds from 50 to 1,000 Hz,
with few fish hearing sounds above 4 kHz (Popper, 2008). It is believed
that most fish have their best hearing sensitivity from 100 to 400 Hz
(Popper, 2003). Permanent hearing loss has not been documented in fish.
A study by Halvorsen et al. (2012) found that for temporary hearing
loss or similar negative impacts to occur, the noise needed to be
within the fish's individual hearing frequency range; external factors,
such as developmental history of the fish or environmental factors, may
result in differing impacts to sound exposure in fish of the same
species. The sensory hair cells of the inner ear in fish can regenerate
after they are damaged, unlike in mammals where sensory hair cells loss
is permanent (Lombarte et al., 1993; Smith et al., 2006). As a
consequence, 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 (Smith et al., 2006), and no permanent loss of
hearing in fish would result from exposure to sound.
Fish species in the Study Area are expected to hear the low-
frequency sources associated with the proposed activities, but most are
not expected to detect sound from the mid-frequency sounds. These
effects are expected to be transient, and long-term consequences for
the population are not expected. Human-generated sound could alter the
behavior of a fish in a manner that would affect its way of living,
such as where it tries to locate food or how well it can locate a
potential mate; behavioral responses to loud noise could include a
startle response, such as the fish swimming away from the source, the
fish ``freezing'' and staying in place, or scattering (Popper, 2003).
Auditory masking could also interfere with a fish's ability to hear
biologically relevant sounds, inhibiting the ability to detect both
predators and prey, and impacting schooling, mating, and navigating
(Popper, 2003). If an individual fish encounters low-frequency acoustic
transmissions and is able to perceive the transmissions, they are
expected to exhibit short-term behavioral reactions, when initially
exposed to acoustic transmissions, which would not significantly alter
breeding, foraging, or populations. Overall effects to fish from active
acoustic sources would be localized, temporary, and infrequent.
Potential Effects on Physical and Foraging Habitat
Ringed seals haul out on pack ice during the spring and summer to
molt (Reeves et al., 2002; Born et al., 2002). Acoustic transmissions
also would have no structural impact to subnivean lairs in the ice.
Furthermore, since ice dampens acoustic transmissions (Richardson et
al., 1995), the level of sound energy that reaches the interior of a
subnivean lair would be less than that ensonifying water under
surrounding ice. Some studies suggested that ringed seals might
preferentially establish breathing holes in ship tracks after vessels
move through the area (Alliston, 1980; Alliston, 1981). The amount of
ice habitat disturbed by activities is small relative to the amount of
overall habitat available and there will be no permanent or longer-term
loss or modification of physical ice habitat used by ringed seals.
Vessel movement would have minimal effect on physical beluga habitat as
beluga habitat is solely within the water column. Furthermore, the
deployed acoustic sources that would remain in use after the vessels
have left the Study Area have low duty cycles and lower source levels,
and any impacts to the acoustic habitat of marine mammals would be
minimal. For these reasons, it is unlikely that ONR's acoustic
activities in the Study Area would have any effect on marine mammal
habitat.
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of the negligible impact determinations and impacts on
subsistence uses.
Harassment is the only type of take expected to result from these
activities. For this 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
[[Page 46070]]
wild by causing disruption of natural behavioral patterns, including,
but not limited to, migration, surfacing, nursing, breeding, feeding,
or sheltering, to a point where the behavioral patterns are abandoned
or significantly altered (Level B harassment).
Authorized takes would be by Level B harassment only, in the form
of behavioral reactions and/or TTS for individual marine mammals
resulting from exposure to active acoustic sources and noise from
icebreaking. Based on the nature of the activity, Level A harassment is
neither anticipated nor proposed to be authorized.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic criteria above which NMFS believes there is
some reasonable potential for marine mammals to be behaviorally
harassed or incur some degree of AUD INJ; (2) the area or volume of
water that will be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas;
and (4) the number of days of activities. We note that while these
factors can contribute to a basic calculation to provide an initial
prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur AUD INJ of some degree (equated to
Level A harassment). We note that the criteria for AUD INJ, as well as
the names of two hearing groups, were updated in 2024 (NMFS, 2024) as
reflected below in the Level A Harassment section.
Level B Harassment
Though significantly driven by received level, the onset of
behavioral disturbance from anthropogenic noise exposure is also
informed to varying degrees by other factors related to the source or
exposure context (e.g., frequency, predictability, duty cycle, duration
of the exposure, signal-to-noise ratio, distance to the source), the
environment (e.g., bathymetry, other noises in the area, predators in
the area), and the receiving animals (hearing, motivation, experience,
demography, life stage, depth) and can be difficult to predict (e.g.,
Southall et al., 2007; Southall et al., 2021; Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-square sound pressure levels (RMS SPL) of 120 dB re 1 [mu]Pa for
continuous (e.g., vibratory pile driving, drilling, icebreaking) and
above RMS SPL 160 dB re 1 [mu]Pa for non-explosive impulsive (e.g.,
seismic airguns) or intermittent (e.g., scientific sonar) sources.
Generally speaking, Level B harassment take estimates based on these
behavioral harassment thresholds are expected to include any likely
takes by TTS as, in most cases, the likelihood of TTS occurs at
distances from the source less than those at which behavioral
harassment is likely. TTS of a sufficient degree can manifest as
behavioral harassment, as reduced hearing sensitivity and the potential
reduced opportunities to detect important signals (conspecific
communication, predators, prey) may result in changes in behavior
patterns that would not otherwise occur.
In coordination with NMFS, the Navy developed behavioral criteria
to support environmental analyses for the Navy's training and testing
activities utilizing active tactical sonar sources. These behavioral
harassment thresholds are used herein to evaluate the potential effects
of the active acoustic components of the proposed activities. As with
other sound sources, exposure to sonar is difficult to predict and is
dependent on received level and other factors such as exposure context,
the environment, and characteristics of the receiving animal.
The Navy updated its behavioral criteria for tactical sonar in 2025
(U.S. Department of the Navy, 2025) for Phase IV of its at-sea training
and testing environmental compliance. However, ONR relied upon the
Phase III criteria and thresholds (U.S. Department of the Navy, 2017)
for the analysis of active acoustic sources in its application. (Note
that it applied the 120 dB re 1 [mu]Pa threshold for icebreaking.) The
Phase IV behavioral response function (BRF) analyses differ from Phase
III due to the addition of new data and the separation of some species
groups. Figure 10 in the Phase IV Criteria and Thresholds Technical
Report (U.S. Department of the Navy, 2025) indicates the changes in
BRFs from Phase III to Phase IV, and NMFS has summarized the odontocete
and pinniped changes here. The Phase IV odontocete BRF is less
sensitive overall due to additional behavioral response research (e.g.,
the 50 percent point of BRF increased by 11 dB from Phase III to Phase
IV). Relying upon the Phase III BRF results in a higher number of
behavioral responses than relying on the Phase IV BRF for the same
event, and it also suggests higher avoidance of auditory effects. The
Phase IV pinniped (in-water) BRF is more sensitive due to the inclusion
of additional captive pinniped data (only three behavioral studies
using captive pinnipeds were available for the derivation of the BRF)
(e.g., the 50 percent of the BRF decreased by 10 dB from Phase III to
Phase IV). Behavioral studies of captive animals can be difficult to
extrapolate to wild animals due to several factors (e.g., use of
trained subjects). With captive studies, behavioral responses are often
correlated with received level, but other factors that may also
contribute to responses (i.e., exposure context, the environment, and
characteristics of the receiving animal) typically cannot be as well
controlled or accounted for. While studies using captive animals may
provide greater control over certain aspects of noise exposure
scenarios and observations, Southall et al. (2021) derived separate
behavioral severity scales to address the fundamental differences
between studies involving captive versus free-ranging animals (e.g.,
severity scale for captive marine mammals, unlike for wild marine
mammals, does not account for fitness-related consequences to survival,
foraging, and reproduction, since population-level effects in captive
studies are less measurable and relevant). This means the Phase IV
pinniped BRF likely overestimates effects compared to observed
responses of wild pinnipeds to sound and anthropogenic activity.
Therefore, while Phase IV BRFs are available, NMFS concurs that use of
the Phase III BRFs adequately estimates the potential impacts to marine
mammals from acoustic sources.
The Navy's tactical sonar BRFs are not applicable to icebreaking
and, therefore, NMFS proposes to adopt ONR's approach of using the 120
dB re 1 [mu]Pa threshold to estimate take of all marine
[[Page 46071]]
mammals by Level B harassment from icebreaking.
For beluga whale, the ONR's take analysis applies cutoff distances,
beyond which the potential of significant behavioral responses (and
therefore Level B harassment) is considered to be unlikely (table 5).
These cutoff distances are consistent with the Phase III cutoffs and
include different cutoff distances for fixed sources (10 km) and
moving/drifting sources (20 km). Fixed sources are treated as
individual sources in ONR's modeling given that the distance between
them is significantly greater than the range to which environmental
effects could occur, while some of the on-site drifting sources could
come closer together. The Phase IV criteria estimate a 15 km cutoff for
odontocetes for both fixed and moving sources. Therefore, the cutoff
distance applied herein for fixed sources would result in a lower take
estimate for beluga whales in comparison to application of the Phase IV
cutoffs, while the cutoff distances for drifting sources would result
in a higher beluga whale take estimate compared to Phase IV cutoffs.
The estimated distance to the Level B harassment isopleth associated
with icebreaking noise is under 5 km for beluga whales and a cutoff
distance was not applied. ONR also did not apply cutoff distances to
ringed seal Level B harassment estimates for any source given the
methodology used to estimate take (described below), and NMFS concurs
they are not warranted.
Table 5--Cutoff Distances and Acoustic Thresholds Identifying the Onset of Behavioral Disturbance, and TTS for Sources by Species
--------------------------------------------------------------------------------------------------------------------------------------------------------
Acoustic sources Icebreaking
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fixed source
behavioral Drifting source Behavioral Behavioral
Hearing group Species threshold cutoff behavioral threshold threshold Range to TTS threshold
distance \a\ cutoff distance \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans....... Beluga whale..... 10 km............. 20 km................. Phase III <15 m \b\......... 120 dB re 1
Odontocete BRF [micro]Pa.
dose-response
function.
Phocidae (in water)............ Ringed seal...... N/A............... N/A................... Phase III <15 m............. 120 dB re 1
Pinniped BRF [micro]Pa.
dose-response
function.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The threshold values provided assume the source is within the animal's best hearing sensitivity (U.S. Department of the Navy, 2017). The exact
threshold varies based on the overlap of the source and the frequency weighting (see figure 6-1 in application).
\a\ Take is not estimated to occur beyond the relevant cutoff distance, regardless of the received level.
\b\ Beluga whale takes by TTS were estimated using the threshold of 178 dB SEL24h but the Navy has since updated the onset TTS threshold to 181 dB
SEL24h.
Level A Harassment
NMFS' Updated Technical Guidance for Assessing the Effects of
Anthropogenic Sound on Marine Mammal Hearing (Version 3.0) (2024
Updated Technical Guidance) (NMFS, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive).
ONR's proposed activity only includes the use of non-impulsive (active
acoustic and icebreaking) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in the table below. The references, analysis,
and methodology used in the development of the criteria are described
in NMFS' 2024 Updated Technical Guidance, which may be accessed at:
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools.
Table 6--Thresholds Identifying the Onset of AUD INJ
[NMFS, 2024]
------------------------------------------------------------------------
AUD INJ onset acoustic thresholds *
(received level)
Hearing group --------------------------------------
Non-impulsive
------------------------------------------------------------------------
High-Frequency (HF) Cetaceans.... Cell 4: LE,HF,24h: 201 dB.
Phocid Pinnipeds (PW) Cell 8: LE,PW,24h: 195 dB.
(Underwater).
------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria
results in the larger isopleth for calculating AUD INJ onset. If a non-
impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria
are recommended for consideration for non-impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1
[micro]Pa, and weighted cumulative sound exposure level (LE,p) has a
reference value of 1 [micro]Pa\2\s. In this table, criteria are
abbreviated to be more reflective of International Organization for
Standardization standards (International Organization for
Standardization (ISO), 2017). The subscript ``flat'' is being included
to indicate peak sound pressure are flat weighted or unweighted within
the generalized hearing range of marine mammals underwater (i.e., 7 Hz
to 165 kHz). The subscript associated with cumulative sound exposure
level criteria indicates the designated marine mammal auditory
weighting function (LF, HF, and VHF cetaceans, and PW and OW
pinnipeds) and that the recommended accumulation period is 24 hours.
The weighted cumulative sound exposure level criteria could be
exceeded in a multitude of ways (i.e., varying exposure levels and
durations, duty cycle). When possible, it is valuable for action
proponents to indicate the conditions under which these criteria will
be exceeded.
To compare NMFS (2024) weighting functions and TTS/AUD INJ SEL
thresholds to NMFS (2018), which were used to predict TTS and AUD INJ
in previous ARA IHAs (83 FR 48799, September 27, 2018; 84 FR 50007,
[[Page 46072]]
September 24, 2019; 85 FR 53333, August 28, 2020; 86 FR 54931, October
5, 2021; 87 FR 57458, September 20, 2022; 88 FR 65657, September 18,
2023; 89 FR 77089, September 20, 2024; 90 FR 43178, September 14,
2025)), both the weighting function shape and the weighted threshold
values were considered; the thresholds (table 6) by themselves indicate
the TTS/AUD INJ threshold at only the most susceptible frequency (based
on the relevant weighting function).
The most significant differences between NMFS (2018) criteria used
in this and previous ARA analyses and NMFS (2024) criteria that are
applicable to beluga whales and ringed seals are: (1) for the HF group
(formerly MF group in NMFS (2018)), NMFS (2024) onset TTS/AUD INJ
thresholds overall are 3 dB higher compared to NMFS (2018) but the NMFS
(2024) weighting function indicates increased susceptibility to noise-
induced hearing loss at frequencies below approximately 10 kHz,
compared to NMFS (2018) which is a result of new TTS onset data for
dolphins at low frequencies (Finneran et al., 2023); and (2) for the
PCW group, new TTS data for harbor seals (Kastelein et al., 2020a;
Kastelein et al., 2020b) resulted in overall 6 dB lower TTS/AUD INJ
thresholds for NMFS (2024), with the NMFS (2024) weighting function
only resulting in slight changes compared to NMFS (2018).
Marine Mammal Occurrence and Take Estimation
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations. We also describe how the information
provided above is synthesized to produce a quantitative estimate of the
take that is reasonably likely to occur and proposed for authorization.
The Navy performed a quantitative analysis to estimate the number
of marine mammals likely to be exposed to underwater acoustic
transmissions above the previously described threshold criteria during
the proposed activity.
Beluga Whales
ONR employed a sophisticated model known as the Navy Acoustic
Effects Model (NAEMO) to assess the estimated impacts of underwater
sound and estimate take of beluga whales.
Inputs to the quantitative analysis included beluga whale density
estimates obtained from the Kaschner et al. (2006) habitat suitability
model and Ca[ntilde]adas et al. (2020), depth occurrence (U.S.
Department of the Navy, 2017b), oceanographic and mammal hearing data,
and criteria and thresholds for levels of potential effects. The
quantitative analysis consists of computer modeled estimates and a
post-model analysis to determine the number of potential animal
exposures. The model calculates sound energy propagation from the
proposed sources, the sound received by animat (virtual animal)
dosimeters representing marine mammals distributed in the area around
the modeled activity, and whether the sound received by animats exceeds
the thresholds for effects.
The Navy developed a set of software tools and compiled data for
estimating acoustic effects on marine mammals without consideration of
behavioral avoidance or mitigation. These tools and data sets serve as
integral components of NAEMO. In NAEMO, animats are distributed non-
uniformly based on species-specific density, depth distribution, and
group size information and animats record energy received at their
location in the water column. A fully three-dimensional environment is
used for calculating sound propagation and animat exposure in NAEMO.
Site-specific bathymetry, sound speed profiles, wind speed, and bottom
properties are incorporated into the propagation modeling process.
NAEMO calculates the likely propagation for various levels of energy
(sound or pressure) resulting from each source used during the event.
NAEMO then records the energy received by each animat within the
energy footprint of the event and calculates the number of animats
having received levels of energy exposures that fall within defined
impact thresholds. Predicted effects on the animats within a scenario
are then tallied and the highest order effect (based on severity of
criteria) predicted for a given animat is assumed. Each scenario, or
each 24-hour period for scenarios lasting greater than 24 hours is
independent of all others, and therefore, the same individual marine
mammal (as represented by an animat in the model environment) could be
impacted during each independent scenario or 24-hour period. In few
instances, although the activities themselves all occur within the
proposed study location, sound may propagate beyond the boundary of the
Study Area. Any exposures occurring outside the boundary of the Study
Area are counted as if they occurred within the Study Area boundary.
NAEMO provides the initial estimated impacts on marine species with a
static horizontal distribution (i.e., animats in the model environment
do not move horizontally but do move vertically within the water
column).
There are limitations to the data used in the acoustic effects
model, and the results must be interpreted within this context. While
the best available data and appropriate input assumptions have been
used in the modeling, when there is a lack of definitive data to
support an aspect of the modeling, conservative modeling assumptions
have been chosen (i.e., assumptions that may result in an overestimate
of acoustic exposures):
Animats are modeled as facing the source and therefore
always predicted to receive the maximum potential sound level at a
given location (i.e., no porpoising or pinnipeds' heads above water);
Animats do not move horizontally (but change their
position vertically within the water column), which may overestimate
physiological effects such as hearing loss, especially for slow moving
or stationary sound sources in the model;
Animats are stationary horizontally and therefore do not
avoid the sound source, unlike in the wild where animals would most
often avoid exposures at higher sound levels, especially those
exposures that may result in AUD INJ (including PTS);
Multiple exposures within any 24-hour period are
accumulated as one continuous exposure for the purposes of calculating
potential threshold shifts, because there are not sufficient data to
estimate a hearing recovery function for the time between intermittent
exposures; and
Mitigation measures were not considered in the model. In
reality, sound-producing activities would be reduced, stopped, or
delayed if marine mammals are detected by visual monitoring.
Due to these inherent model limitations and simplifications, model-
estimated results should be further analyzed, considering such factors
as the range to specific effects, avoidance, and the likelihood of
successfully implementing mitigation measures. This analysis uses a
number of factors in addition to the acoustic model results to predict
acoustic effects on marine mammals.
The beluga whale density numbers utilized for quantitative acoustic
modeling are from the Navy Marine Species Density Database (U.S.
Department of the Navy, 2014), as more recent densities in the Arctic
are not yet available. Where available (i.e., June through 15 October
over the continental shelf primarily), ONR used density estimates from
Duke density modeling
[[Page 46073]]
based upon line-transect surveys (Ca[ntilde]adas et al., 2020). The
remaining seasons and geographic area were based on the habitat-based
modeling by Kaschner (2004) and Kaschner et al. (2006). Beluga whale
density in the Study Area varies geographically and monthly, with
densities during September ranging from 0.000506 to 0.5176 animals/
km\2\ and densities during the cold season ranging from 0.002277 to
0.009109 animals/km\2\. Because density estimates for beluga whales
were not distinguished by stock in the Arctic (Kaschner, 2004; Kaschner
et al., 2006), ONR utilized the density range for the month of
September (the month the first research cruise is proposed to begin in
Year 9) and assumed the density of each stock is the same (0.000506 to
0.5176 animals/km\2\). The ranges of the Beaufort Sea stock and Eastern
Chukchi Sea stock of beluga whales vary within the Study Area
throughout the year (Hauser et al., 2014). Based upon the limited
information available regarding the expected spatial distributions of
each stock within the Study Area, NMFS has assumed all takes of beluga
whale could occur to either stock. In addition, in NAEMO, animats do
not move horizontally or react in any way to avoid sound, therefore,
the current model may overestimate non-impulsive acoustic impacts.
ONR reported sightings of beluga whales during previous years of
ARA, though all sightings have occurred during transit and outside of
icebreaking and research activities (i.e., AUV recovery and deployment,
mooring recovery and deployment).
Active Acoustic Sources
The model-estimated take by Level B harassment from active acoustic
sources is listed in table 8. Of note, the Phase IV BRF for the
odontocete behavioral group shows that the 50 percent probability of
response is at a higher received level (168 dB re 1 uPa) than in Phase
III (157 dB re 1 uPa), thus, application of the Phase IV BRF would have
resulted in a lower number of estimated takes by Level B harassment
than what ONR modeled and NMFS is proposing to authorize.
Modeling did not predict, and ONR did not request, take by Level A
harassment. While beluga whale take was modeled using NMFS (2018) and
the NMFS (2024) onset TTS/AUD INJ thresholds are overall 3 dB higher
with the updated weighting function indicating greater susceptivity to
noise-induced hearing loss at frequencies below approximately 10 kHz,
NMFS does not anticipate that application of NMFS (2024) would have
resulted in take by Level A harassment either, given that the acoustic
sources are continuous with a low duty cycle and relatively short ping
duration (4-30 seconds). Therefore, NMFS concurs and is not proposing
to authorize take of beluga whale by Level A harassment from active
acoustic sources.
Icebreaking
Since ice conditions cannot be predicted more than a few weeks in
advance, ONR cannot predict whether icebreaking would be needed to
deploy or retrieve the sources after 1 year of transmitting. Therefore,
ONR analyzed the potential for an icebreaking cruise on CGC HEALY in
its application to avoid underestimating potential impacts. As the R/V
Sikuliaq is not capable of icebreaking, noise created by icebreaking is
only modeled for the CGC HEALY. ONR assumed icebreaking would occur for
8 days and used NAEMO modeling to estimate takes of beluga whales
associated from icebreaking activities using the density range 0.000506
to 0.5176 animals/km\2\.
Roth et al. (2013) characterized the underwater radiated noise
signature for icebreaking in the central Arctic Ocean by CGC HEALY
during different types of ice-cover. The radiated noise signatures were
characterized for various fractions of ice cover. ONR used the 8/10 and
3/10 ice cover for modeling. Each modeled day of icebreaking consisted
of 16 hours of 8/10 ice cover and 8 hours of 3/10 ice cover. The sound
signature of the 5/10 icebreaking activities, which would correspond to
half-power icebreaking, was not reported in Roth et al. (2013);
therefore, ONR used the full-power signature as a proxy for the half-
power signature.
Figures 5a and 5b in Roth et al. (2013) depict the source spectrum
level versus frequency for 8/10 and 3/10 ice cover, respectively. The
sound signature of each of the ice coverage levels was broken into
single-octave bins (table 7). In the model, each bin was included as a
separate source on the modeled vessel. When these independent sources
are active concurrently, they simulate the sound signature of CGC
HEALY. The modeled broadband source level summed across these bins was
196.2 dB for the 8/10 signature and 189.3 dB for the 3/10 ice
signature. These modeled broadband source levels are a good
approximation of the icebreaker's observed source level (provided in
figure 4b of Roth et al. (2013)). Each frequency and source level was
modeled as an independent source and applied simultaneously to all of
the animats within NAEMO. Each second was summed across frequency to
estimate the RMS SPL. Any animat exposed to sound levels greater than
120 dB was considered taken by Level B harassment. For AUD INJ
(including PTS) and TTS determinations, sound exposure levels were
summed over the duration of the test and the transit to the deep water
deployment area.
Table 7--Modeled Bins for 8/10 Ice Coverage (Full Power) and 3/10 Ice
Coverage (Quarter Power) Icebreaking on CGC HEALY
------------------------------------------------------------------------
8/10 3/10
Frequency (Hz) source source
level (dB) level (dB)
------------------------------------------------------------------------
25.............................................. 189 187
50.............................................. 188 182
100............................................. 189 179
200............................................. 190 177
400............................................. 188 175
800............................................. 183 170
1,600........................................... 177 166
3,200........................................... 176 171
6,400........................................... 172 168
12,800.......................................... 167 164
------------------------------------------------------------------------
Table 8 shows the takes by Level B harassment that NMFS proposes to
authorize for both beluga whale stocks. Take by Level A harassment from
icebreaking activities is neither anticipated nor proposed for
authorization for either stock. Modeling for all previous years of ARA
icebreaking activities did not result in any estimated take by Level A
harassment of marine mammals. Given the proposed icebreaking activities
have not changed, and that icebreaking is a continuous noise source,
neither ONR nor NMFS expect the icebreaking activities during Year 9
would result in Level A harassment of beluga whales, even if the Phase
IV criteria had been applied. Therefore, Level A harassment is neither
anticipated nor proposed for authorization.
Ringed Seals
The most recent density estimates for ringed seals are based on the
habitat suitability modeling by Kaschner (2004) and Kaschner et al.
(2006). Given the lack of recent density estimates for the Study Area
to estimate impacts from active acoustic sources, ONR, and subsequently
NMFS, relied, in part, upon historical sightings registered in the
Ocean Biodiversity Information System Spatial Ecological Analysis of
Megavertebrate Populations (OBIS-SEAMAP) database (Halpin et al., 2009)
in the Study Area. Of these sightings, nearly all (99 percent) occurred
in
[[Page 46074]]
summer and fall seasons. However, it is unclear whether this is because
ringed seals move out of the Study Area during the cold season, or if
the lack of sightings is due to the harsh environment and ringed seal
behavior being prohibitive factors for cold season surveying.
OBIS-SEAMAP reports 542 animals sighted over 150 records in the
Study Area across all years and seasons. The average of 542 animals in
150 records (approximately 3.6 animals per record) aligns with survey
data from previous ARA cruises that show up to three ringed seals (or
small, unidentified pinnipeds assumed to be ringed seals) sighted per
day in the Study Area. To account for potential unsighted animals, ONR
rounded that number up to 4. Assuming that four animals would be
present in the Study Area, ONR estimated a rough density using the
overall Study Area size:
4 ringed seals / 48,725 km\2\ = 0.00008209 ringed seals/km\2\
ONR reported sightings of ringed seals during previous years of
ARA, though most sightings have occurred during transit and outside of
icebreaking and research activities (i.e., AUV recovery and deployment,
mooring recovery and deployment). ONR reported that during all previous
years of ARA, the only mitigations enacted during research activities
(with active acoustic source use) that required the source to be shut
down were during: (1) deployment of a REMUS UUV in Year 4; and (2)
deployment of an AMOS mooring in Year 4 (both shutdowns due to presence
of a seal). Other mitigations to halt activities have occurred during
icebreaking and research activities in previous ARA but no shutdowns of
active acoustic sources have been required outside of those in Year 4.
Active Acoustic Sources
The Level B harassment zone surrounding each moored active acoustic
source would be 78.5 km\2\, and the Level B harassment zone surrounding
each drifting active acoustic source would be 314 km\2\. The total
Level B harassment zone area from acoustic sources on any given day
would be 1,099 km\2\. Using that area, and the density calculated
above, ONR estimates the number of ringed seals that could be taken
daily:
0.00008209 ringed seals/km\2\ x 1,099 km\2\ = 0.09 ringed seals/day
ONR assumed that one ringed seal would be exposed to acoustic
transmissions above the threshold for Level B harassment, and that each
would be exposed each day of the proposed activity (365 days total).
Although there are two additional acoustic sources proposed for use
during Year 9, the number of daily takes of ringed seals is still
expected to be less than one (rounded up to one per day). Therefore,
NMFS anticipates 365 takes by Level B harassment of ringed seal from
active acoustic sources (table 8).
This take estimation method used here does not support ONR or NMFS
differentiating takes by Level B harassment between direct behavioral
disturbance and TTS; however, NMFS does not anticipate TTS of ringed
seals from active acoustic sources. Since potentially impactful source
levels from acoustic sources would not exceed 185 dB by system design
limits, sound exposure levels would remain relatively low. Accounting
for source level, spherical spreading, and a 30-sec pulse length (table
1), a ringed seal would need to be in very close range of a single ping
of an acoustic source to risk exposure at or above the TTS threshold,
an unlikely scenario given the low density of ringed seals in the Study
Area. Given the exceedingly low potential for TTS, AUD INJ is not
anticipated either. Therefore, ONR did not request, and NMFS is not
proposing to authorize, take of ringed seal by Level A harassment from
active acoustic sources.
Icebreaking
For icebreaking activities, NMFS assumes that each ringed seal in
the Study Area could be taken by Level B harassment on each day of
icebreaking. Therefore, NMFS is proposing to authorize 32 takes by
Level B harassment (4 animals x 8 days) of ringed seal from icebreaking
activities. Table 8 shows the takes by Level B harassment that NMFS
proposes to authorize for ringed seal.
Take by Level A harassment from icebreaking activities is neither
anticipated nor proposed for authorization. Modeling for all previous
years of ARA icebreaking activities did not result in any estimated
take by Level A harassment of marine mammals. Given the proposed
icebreaking activities have not changed, and that icebreaking is a
continuous noise source, neither ONR nor NMFS expect the icebreaking
activities during Year 9 would result in Level A harassment, even if
the Phase IV criteria had been applied. Therefore, Level A harassment
of ringed seals from icebreaking is neither anticipated nor proposed
for authorization.
Table 8--Proposed Take by Level B Harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Active Total proposed Percentage of
Species Stock acoustics Icebreaking take SAR abundance population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Beluga whale............................ Beaufort Sea............... 177 21 198 39,258 <1
Chukchi Sea................ 13,305 1.5
Ringed seal............................. Arctic..................... 365 32 397 UND \a\ (171,418) <1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Acoustic and icebreaking exposures to beluga whales were not modeled at the stock level as the density value is not distinguished by stock in the
Arctic for beluga whales (U.S. Department of the Navy, 2014). Estimated take of beluga whales due to active acoustics is 177 and 21 due to icebreaking
activities, totaling 198 takes of beluga whales. The total proposed take of beluga whales was applied to each stock.
\a\ A reliable population estimate for the entire Arctic stock of ringed seals is not available and NMFS SAR lists it as Undetermined (UND). Using a sub-
sample of data collected from the U.S. portion of the Bering Sea (Conn et al., 2014), an abundance estimate of 171,418 ringed seals has been
calculated but this estimate does not account for availability bias due to seals in the water or in the shore-fast ice zone at the time of the survey.
The actual number of ringed seals in the U.S. portion of the Bering Sea is likely much higher. Using the minimum population size (Nmin = 158,507)
based upon this negatively biased population estimate, the PBR is calculated to be 4,755 seals, although this is also a negatively biased estimate.
Proposed Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses.
[[Page 46075]]
NMFS regulations require applicants for incidental take authorizations
to include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks, and their habitat (50 CFR
216.104(a)(11)). The 2004 NDAA amended the MMPA as it relates to
military readiness activities and the incidental take authorization
process such that ``least practicable impact'' shall include
consideration of personnel safety, practicality of implementation, and
impact on the effectiveness of the military readiness activity.
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat, as
well as subsistence uses. This considers the nature of the potential
adverse impact being mitigated (likelihood, scope, range). It further
considers the likelihood that the measure will be effective if
implemented (probability of accomplishing the mitigating result if
implemented as planned), the likelihood of effective implementation
(probability implemented as planned); and
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, impact on
operations, and, in the case of a military readiness activity,
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
The mitigation requirements described in the following were
proposed by ONR in its adequate and complete application or are the
result of subsequent coordination between NMFS and ONR. ONR has agreed
that all of the mitigation measures are practicable. NMFS has fully
reviewed the specified activity and the mitigation measures to
determine if the mitigation measures would result in the least
practicable adverse impact on marine mammals and their habitat, as
required by the MMPA, and has determined the proposed measures are
appropriate. NMFS describes these below as proposed mitigation
requirements, and has included them in the proposed IHA.
The following measures are proposed for this IHA:
All vessels operated by or for the Navy must have
personnel assigned to stand watch at all times while underway. Watch
personnel must employ visual search techniques using binoculars. While
underway and while using active acoustic sources/towed in-water
devices, at least one person with access to binoculars is required to
be on watch at all times.
Vessel captains and vessel personnel must remain alert at
all times, proceed with extreme caution, and operate at a safe speed so
that the vessel can take proper and effective action to avoid vessel
strike of marine mammals.
During moored and drifting acoustic source deployment and
recovery, ONR must implement a mitigation zone of 55 m around the
deployed source. Deployment and recovery must cease if a marine mammal
is visually detected within the mitigation zone. Deployment and
recovery may recommence if any one of the following conditions are met:
[cir] A watch stander observes the animal is observed exiting the
mitigation zone;
[cir] A watch stander concludes that the animal has exited the
mitigation zone based on its observed course, speed, and movement
relative to the mitigation zone; and
[cir] A watch stander affirms the mitigation zone has been clear
from any additional sightings for a period of 15 minutes for pinnipeds
and 30 minutes for cetaceans.
Vessels must avoid approaching marine mammals head-on and
must maneuver to maintain a mitigation zone of 457 m around all
observed cetaceans and 183 m around all other observed marine mammals,
provided it is safe to do so.
Activities must cease if a marine mammal species for which
take was not authorized, or a species for which authorization was
granted but the authorized number of takes have been met, is observed
approaching or within the mitigation zone (table 9). Activities must
not resume until the animal is confirmed to have left the area.
Vessel captains must maintain at-sea communication with
subsistence hunters to avoid conflict of vessel transit with hunting
activity.
Table 9--Proposed Mitigation Zones
------------------------------------------------------------------------
Mitigation
Activity and/or effort type Species zone (m)
------------------------------------------------------------------------
Acoustic source deployment and Beluga whale........ 55
recovery, stationary.
Acoustic source deployment and Ringed seal......... 55
recovery, stationary.
Transit........................... Beluga whale........ 457
Transit........................... Ringed seal......... 183
------------------------------------------------------------------------
NMFS conducted an independent evaluation of the proposed measures,
and has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable impact on the
affected species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, areas of similar significance,
and on the availability of such species or stock for subsistence uses.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that 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
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 while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
[[Page 46076]]
Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the activity; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
Mitigation and monitoring effectiveness.
The monitoring and reporting requirements described in the
following were proposed by ONR in its adequate and complete application
or are the result of subsequent coordination between NMFS and ONR. ONR
has agreed to the requirements. NMFS describes these below as
requirements and has included them in the proposed IHA.
The initial structure for the U.S. Navy's marine species monitoring
efforts was developed in 2009 with the Integrated Comprehensive
Monitoring Program (ICMP). The intent of the ICMP was to provide an
overarching framework for coordination of the Navy's monitoring efforts
during the early years of the program's establishment. A Strategic
Planning Process (U.S. Department of the Navy, 2013) was subsequently
developed and together with the ICMP framework serves as a planning
tool to focus marine species monitoring priorities defined by ESA and
MMPA requirements, and to coordinate monitoring efforts across regions
based on a set of common objectives. Using an underlying conceptual
framework incorporating a progression of knowledge from occurrence to
exposure/response, and ultimately consequences, the Strategic Planning
Process was developed as a tool to help guide the investment of
resources to address top level objectives and goals of the monitoring
program most efficiently. The Strategic Planning Process identifies
Intermediate Scientific Objectives (see https://www.navymarinespeciesmonitoring.us/about/strategic-planning-process/),
which form the basis of evaluating, prioritizing, and selecting new
monitoring projects or investment topics and serve as the basis for
developing and executing new monitoring projects across the Navy's
training and testing ranges (both Atlantic and Pacific).
A Research and Monitoring Summit was held in early 2023 to evaluate
the current state of the Marine Species Monitoring Program in terms of
progress, objectives, priorities, and needs, and to solicit valuable
input from meeting participants including NMFS, Marine Mammal
Commission, Navy, and scientific experts. The overarching goal of the
summit was to facilitate updating the ICMP framework for guiding marine
species research and monitoring investments, and to identify data gaps
and priorities to be addressed over the next 5-10 years across a range
of basic research through applied monitoring. One of the outcomes of
this summit meeting is a refreshed strategic framework effectively
replacing the ICMP which will provide increased coordination and
synergy across the Navy's protected marine species investment programs.
This will contribute to the collective goal of supporting improved
assessment of effects from training and testing activities through
development of first in class science and data.
Navy marine species monitoring is generally focused on Navy
training and testing ranges where the majority of Navy activities occur
regularly as those areas have the greatest potential for being
impacted. ONR's ARA are comparatively less intensive with little human
activity in the Arctic. Human presence is limited to the deployment of
sources that would take place over several weeks. Additionally, due to
the location and nature of the testing, vessels and personnel would not
be within the Study Area for an extended period of time. As such, more
extensive monitoring requirements beyond the collection of basic
information during source deployment would not be feasible as it would
require additional personnel and equipment in the Arctic during a
period of time beyond what is planned for source deployment; however,
ONR will conduct monitoring when personnel are at sea for source
deployment or retrieval, as described below.
Marine mammal monitoring must be conducted in accordance with the
Navy's strategic monitoring framework and the proposed IHA:
While underway, all vessels must have at least one person
trained through the U.S. Navy Marine Species Awareness Training Program
on watch during all activities;
Watch personnel must use standardized data collection
forms, whether hard copy or electronic. Watch personnel must
distinguish between sightings that occur during transit or during
deployment or recovery of acoustic sources. Data must be recorded on
all days of activities, even if marine mammals are not sighted;
At minimum, the following information must be recorded:
vessel name; watch personnel names and affiliation; effort type (i.e.,
transit, deployment, recovery); and environmental conditions (at the
beginning of watch stander shift and whenever conditions change
significantly), including Beaufort Sea State (BSS) and any other
relevant weather conditions, including cloud cover, fog, sun glare, and
overall visibility to the horizon.
Upon visual observation of any marine mammal, the
following information must be recorded: date/time of sighting;
identification of animal (e.g., genus/species, lowest possible
taxonomic level, or unidentified) and the composition of the group if
there is a mix of species; location (latitude/longitude) of sighting;
estimated number of animals (high/low/best); description (as many
distinguishing features as possible of each individual seen, including
length, shape, color, pattern, scars or markings, shape and size of
dorsal fin, shape of head, and blow characteristics); detailed behavior
observations (e.g., number of blows/breaths, number of surfaces,
breaching, spyhopping, diving, feeding, traveling; as explicit and
detailed as possible; length of time observed in the mitigation zone,
note any observed changes in behavior); distance from vessel to animal;
direction of animal's travel relative to the vessel; platform activity
at time of sighting (i.e., transit, deployment, recovery); and weather
conditions (i.e., BSS, cloud cover).
During icebreaking, the following information must be
recorded: start and end time of icebreaking; and ice cover conditions.
[[Page 46077]]
During deployment and recovery of acoustic sources or
UUVs, visual observation must begin 30 minutes prior to deployment or
recovery and continue through 30 minutes following the source
deployment or recovery.
ONR must submit its draft report(s) on all monitoring
conducted under the IHA within 90 calendar days of the completion of
monitoring or 60 calendar days prior to the requested issuance of any
subsequent IHA for research activities at the same location, whichever
comes first. A final report must be prepared and submitted within 30
calendar days following receipt of any NMFS comments on the draft
report. If no comments are received from NMFS within 30 calendar days
of receipt of the draft report, the report shall be considered final.
The marine mammal report, at minimum, must include: dates
and times (begin and end) of all marine mammal monitoring; acoustic
source use or icebreaking; watch stander location(s) during marine
mammal monitoring; environmental conditions during monitoring periods
(at beginning and end of watch standing shift and whenever conditions
change significantly), including BSS and any other relevant weather
conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance; number of
shutdowns during monitoring, if any; marine mammal sightings (including
the marine mammal's location (latitude/longitude)); number of
individuals of each species observed during source deployment,
operation, and recovery; and detailed information about implementation
of any mitigation (e.g., shutdowns, delays), a description of specific
actions that ensued, and resulting changes in behavior of the
animal(s), if any.
[cir] Upon observation of a marine mammal, the following
information: name of watch stander who sighted the animal(s), the watch
stander location, and activity at time of sighting; time of sighting;
identification of the animal(s) (e.g., genus/species, lowest possible
taxonomic level, or unidentified), watch stander confidence in
identification, and the composition of the group if there is a mix of
species; distance and location of each observed marine mammal relative
to the acoustic source or icebreaking for each sighting; estimated
number of animals (min/max/best estimate); estimated number of animals
by cohort (adults, juveniles, neonates, group composition, etc.);
animal's closest point of approach and estimated time spent within the
harassment zone; and description of any marine mammal behavioral
observations (e.g., observed behaviors such as feeding or traveling),
including an assessment of behavioral responses thought to have
resulted from the activity (e.g., no response or changes in behavioral
state such as ceasing feeding, changing direction, flushing, or
breaching).
ONR must submit all watch stander data electronically in a
format that can be queried, such as a spreadsheet or database (i.e.,
digital images of data sheets are not sufficient).
Reporting injured or dead marine mammals:
[cir] In the event that personnel involved in the specified
activity discover an injured or dead marine mammal, ONR must report the
incident to the Office of Protected Resources (OPR), NMFS
([email protected] and [email protected]) and to
the Alaska regional stranding network (877-925-7773) as soon as
feasible. If the death or injury was clearly caused by the specified
activity, ONR must immediately cease the activities until NMFS OPR is
able to review the circumstances of the incident and determine what, if
any, additional measures are appropriate to ensure compliance with the
terms of this IHA. ONR must not resume their activities until notified
by NMFS.
[cir] The report must include the following information: time,
date, and location (latitude/longitude) of the first discovery (and
updated location information if known and applicable); species
identification (if known) or description of the animal(s) involved;
condition of the animal(s) (including carcass condition if the animal
is dead); observed behaviors of the animal(s), if alive; if available,
photographs or video footage of the animal(s); and general
circumstances under which the animal was discovered.
In the event of a vessel strike of a marine mammal by any
vessel involved in the activities covered by the authorization, ONR
shall report the incident to OPR, NMFS and to the Alaska regional
stranding coordinator as soon as feasible. The report must include the
following information: time, date, and location (latitude/longitude) of
the incident; species identification (if known) or description of the
animal(s) involved; vessel's speed during and leading up to the
incident; vessel's course/heading and what operations were being
conducted (if applicable); status of all sound sources in use;
description of avoidance measures/requirements that were in place at
the time of the strike and what additional measures were taken, if any,
to avoid strike; environmental conditions (e.g., wind speed and
direction, BSS, cloud cover, visibility) immediately preceding the
strike; estimated size and length of animal that was struck;
description of the behavior of the marine mammal immediately preceding
and following the strike; if available, description of the presence and
behavior of any other marine mammals immediately preceding the strike;
estimated fate of the animal (e.g., dead, injured but alive, injured
and moving, blood or tissue observed in the water, status unknown,
disappeared); and to the extent practicable, photographs or video
footage of the animal(s).
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), 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 baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the discussion of our analysis applies to
beluga whales and ringed seals, given that the anticipated effects of
this activity on these species are expected to be similar. Where there
are meaningful differences between species or stocks, or groups of
species, in anticipated individual
[[Page 46078]]
responses to activities, impact of expected take on the population due
to differences in population status, or impacts on habitat, they are
described independently in the analysis below.
Underwater acoustic transmissions associated with the proposed ARA,
as outlined previously, have the potential to result in Level B
harassment of beluga seals and ringed seals in the form of behavioral
disturbances. No serious injury, mortality, or Level A harassment are
anticipated to result from these described activities. Effects on
individual belugas or ringed seals taken by Level B harassment could
include alteration of dive behavior and/or foraging behavior, effects
to breathing rates, interference with or alteration of vocalization,
avoidance, and flight. More severe behavioral responses are not
anticipated due to the localized, intermittent use of active acoustic
sources. Exposure duration is likely to be short-term and individuals
will, most likely, simply be temporarily displaced by moving away from
the acoustic source. Exposures are, therefore, unlikely to result in
any significant realized decrease in fitness for affected individuals
or adverse impacts to stocks as a whole.
The Study Area overlaps beluga whale migratory and feeding BIAs
(Clarke et al., 2023). Due to the small amount of overlap between the
BIAs and the Study Area, as well as the low intensity and short-term
duration of acoustic sources and required mitigation measures, we
expect minimal impacts to migrating or feeding belugas. Shutdown zones
are expected to minimize the severity of any Level B harassment. The
requirements of trained dedicated watch personnel and speed
restrictions will also reduce the likelihood of any vessel strikes to
migrating belugas.
In all, the proposed activity is expected to have minimal adverse
effects on marine mammal habitat. While the activities may cause some
fish to leave the area of disturbance, temporarily impacting marine
mammals' foraging opportunities, this would encompass a relatively
small area of habitat leaving large areas of existing fish and marine
mammal foraging habitat unaffected. As such, the impacts to marine
mammal habitat are not expected to impact the health or fitness of any
marine mammals.
In summary and as described above, the following factors primarily
support our preliminary determination that the impacts resulting from
this activity are not expected to adversely affect any of the species
or stocks through effects on annual rates of recruitment or survival:
No Level A harassment, serious injury, or mortality is
anticipated or authorized;
Take would be limited to Level B harassment only;
Only temporary and relatively low-level behavioral
disturbances are expected to result from the proposed activities; and
Impacts to marine mammal prey or habitat will be minimal
and short term.
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 proposed activity will have a negligible impact on
all affected marine mammal species or stocks.
Unmitigable Adverse Impact Analysis and Determination
In order to issue an IHA, 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.
Subsistence hunting is important for many Alaska Native
communities. A study of the North Slope villages of Nuiqsut, Kaktovik,
and Utqia[gdot]vik identified the primary resources used for
subsistence and the locations for harvest (Stephen R. Braund &
Associates, 2010), including terrestrial mammals, birds, fish, and
marine mammals (bowhead whale, ringed seal, bearded seal, and walrus).
Ringed seals and beluga whales are likely located within the project
area during this proposed activity, yet the proposed activity would not
remove individuals from the population nor behaviorally disturb them in
a manner that would affect their behavior more than 100 km farther
inshore where subsistence hunting occurs. The proposed sources would be
placed far outside of the range for subsistence hunting. The closest
active acoustic source (fixed or drifting) within the proposed project
site that is likely to cause Level B harassment is approximately 204 km
from land. This ensures a significant standoff distance from any
subsistence hunting area. The closest distance to subsistence hunting
(130 km) is well beyond the largest distance from the sound sources in
use at which behavioral harassment would be expected to occur (20 km)
described above. Furthermore, there is no reason to believe that any
behavioral disturbance of beluga whales or ringed seals that occurs far
offshore (we do not anticipate any Level A harassment) would affect
their subsequent behavior in a manner that would interfere with
subsistence uses should those animals later interact with hunters.
In addition, ONR has been communicating with the Native communities
about the proposed activity. The ONR-sponsored chief scientist for AMOS
has historically provided a briefing on ONR research for the upcoming
year at the December Alaska Eskimo Whaling Commission (AEWC) meetings
and is scheduled to present at the July 2026 meeting. The AEWC consists
of representatives from 11 whaling villages (Wainwright,
Utqia[gdot]vik, Savoonga, Point Lay, Nuiqut, Kivalina, Kaktovik, Wales,
Point Hope, Little Diomede, and Gambell). These briefings have
communicated the lack of any effect on subsistence hunting due to the
distance of the sources from hunting areas. ONR-supported scientists
also attend Arctic Waterways Safety Committee and AEWC meetings on a
regular basis to discuss past, present, and future research activities.
While no take is anticipated to result during transit, points of
contact for at-sea communication will also be established between
vessel captains and subsistence hunters to avoid any conflict of ship
transit with hunting activity.
Based on the description of the specified activity, the measures
described to minimize adverse effects on the availability of marine
mammals for subsistence purposes, and the proposed mitigation and
monitoring measures, NMFS has preliminarily determined that there will
not be an unmitigable adverse impact on subsistence uses from ONR's
proposed activities.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency ensures that any action it
authorizes, funds, or carries out is not likely to jeopardize the
continued existence of any endangered or threatened species or result
in the destruction or adverse modification of
[[Page 46079]]
designated critical habitat. To ensure ESA compliance for the issuance
of incidental take authorizations, NMFS consults internally whenever we
propose to authorize take for ESA-listed species, in this case with
NMFS Alaska Regional Office (AKR).
There is one marine mammal species (Arctic stock of ringed seal)
with confirmed occurrence in the Study Area that is listed as
threatened under the ESA. The NMFS AKR issued a Biological Opinion on
September 13, 2022, under section 7 of the ESA, on the issuance of an
IHA to ONR under section 101(a)(5)(D) of the MMPA by the NMFS OPR. The
Biological Opinion concluded that the action is not likely to
jeopardize the continued existence of Arctic ringed seals, and is not
likely to destroy or adversely modify Arctic ringed seal critical
habitat.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to ONR for conducting a ninth year of ARA in the Beaufort
and Chukchi Seas from September 2026 through September 2027, provided
the previously mentioned mitigation, monitoring, and reporting
requirements are incorporated. A draft of the proposed IHA can be found
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
Request for Public Comments
We request comment on our analyses, the proposed authorization, and
any other aspect of this notice of proposed IHA for the proposed ARA.
We also request comment on the potential renewal of this proposed IHA
as described in the paragraph below. Please include with your comments
any supporting data or literature citations to help inform decisions on
the request for this IHA or a subsequent renewal IHA.
On a case-by-case basis, NMFS may issue a one-time, 1-year renewal
IHA following notice to the public providing an additional 15 days for
public comments when (1) up to another year of identical or nearly
identical activities as described in the Description of Proposed
Activity section of this notice is planned or (2) the activities as
described in the Description of Proposed Activity section of this
notice would not be completed by the time the IHA expires and a renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
A request for renewal is received no later than 60 days
prior to the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond 1 year from expiration
of the initial IHA).
The request for renewal must include the following:
1. An explanation that the activities to be conducted under the
requested renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or include changes so
minor (e.g., reduction in pile size) that the changes do not affect the
previous analyses, mitigation and monitoring requirements, or take
estimates (with the exception of reducing the type or amount of take).
2. A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized.
Upon review of the request for renewal, the status of the
affected species or stocks, and any other pertinent information, NMFS
determines that there are no more than minor changes in the activities,
the mitigation and monitoring measures will remain the same and
appropriate, and the findings in the initial IHA remain valid.
Dated: July 20, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-14816 Filed 7-21-26; 8:45 am]
BILLING CODE 3510-22-P