[Federal Register Volume 90, Number 218 (Friday, November 14, 2025)]
[Notices]
[Pages 51043-51067]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-19886]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF065]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to U.S. Navy Ice Exercise Activities
2026 in the Arctic Ocean
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 U.S. Department of the
Navy (hereafter Navy) for authorization to take marine mammals
incidental to U.S. Navy Ice Exercise Activities 2026 (ICEX26) in the
Arctic Ocean. 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 activities. 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. The Navy'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 December
15, 2025.
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://
[[Page 51044]]
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.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (collectively referred to as
``mitigation''); and requirements pertaining to the monitoring and
reporting of the takings. The definitions of all applicable MMPA
statutory terms used above are included in the relevant sections below
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS
regulations at 50 CFR 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.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA request.
Summary of Request
On May 19, 2025, NMFS received a request from the Navy for an IHA
to take marine mammals incidental to submarine training and testing
activities in the Arctic Ocean. The application was deemed adequate and
complete on July 10, 2025. The Navy's request is for take of ringed
seal (Pusa hispida) by Level B harassment only. Neither the Navy nor
NMFS expect serious injury or mortality to result from this activity
and, therefore, an IHA is appropriate.
NMFS previously issued IHAs to the Navy for similar activities (83
FR 6522, February 14, 2018; 85 FR 6518, February 5, 2020; 87 FR 7803,
February 10, 2022; 89 FR 8172, February 1, 2024). The Navy 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 Potential Effects of the Specified Activity
on Marine Mammals and their Habitat section.
Description of Proposed Activity
Overview
The Navy proposes to conduct submarine training and testing
activities, including establishment of a tracking range and temporary
ice camp, and to conduct research activities in the Arctic Ocean for
approximately 6 weeks beginning in February 2026. Active acoustic
transmissions may result in take by Level B harassment, including
temporary hearing impairment (temporary threshold shift (TTS)) and
behavioral harassment, of ringed seals.
Dates and Duration
The specified activities would occur over approximately a 6-week
period between February and April 2026, including deployment and
demobilization of the ice camp. The submarine training and testing
activities would occur over approximately 4 weeks during the 6-week
period. The proposed IHA would be effective from February 18, 2026
through April 30, 2026.
Geographic Region
The ice camp would be established approximately 185 to 370
kilometers (km) north of Prudhoe Bay, Alaska, in the same study area
defined in the 2025 Draft Environmental Assessment/Overseas
Environmental Assessment (EA/OEA) for Ice Exercise 2026 (hereafter 2025
Draft EA/OEA for ICEX26) (available at https://www.nepa.navy.mil/icex/
); the exact location cannot be identified in advance, as many of the
required conditions (e.g., ice cover) cannot be forecasted until
shortly before the exercises are expected to commence. Prior to
establishment of the ice camp, reconnaissance flights would be
conducted to locate suitable ice conditions required for the location
of the ice camp. The reconnaissance flights would occur over an area of
approximately 70,374 square km (km\2\), while the actual ice camp would
be no more than 1.6 km in diameter, (approximately 2 km\2\ in area).
The vast majority of submarine training and testing would occur near
the ice camp; however, some submarine training and testing may occur
throughout the deep Arctic Ocean basin near the North Pole, within the
larger Navy Activity Study Area. Figure 1 shows the locations of the
Navy Activity Study Area and the
[[Page 51045]]
Ice Camp Study Area, collectively referred to as the ICEX Study Area.
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Detailed Description of the Specified Activity
The Navy proposes to conduct submarine training and testing
activities (i.e., establishment of a portable tracking range and
temporary ice camp, research activities, unmanned underwater vehicle
(UUV) testing, unmanned aerial system (UAS) testing, submarine-launched
non-explosive torpedo exercises) involving underwater active acoustic
transmissions (active sonar), in a large area of the Arctic Ocean north
of Prudhoe Bay, Alaska during a period of approximately 6 weeks
beginning in February 2026. The activity proposed for 2026 and that is
being evaluated for this proposed IHA--ICEX26--is part of a regular
cycle of recurring training and testing activities that the Navy
proposes to conduct in the Arctic, under which submarine and tracking
range activities would be conducted biennially. Some of the submarine
training and testing may occur throughout the deep Arctic Ocean basin
near the North Pole, within the Navy Activity Study Area (figure 1).
Additional information about the Navy's proposed training and
testing activities in the Arctic is available in the 2025 Draft EA/OEA
for ICEX26 (https://www.nepa.navy.mil/icex/). Only activities which may
occur during ICEX26 are discussed in this section.
Ice Camp
ICEX26 includes deployment of a temporary camp situated on an ice
floe. Prior to the set-up of the ice camp, reconnaissance flights will
be conducted to locate suitable ice conditions required for the
location of the ice camp. The ice camp would consist of a command hut,
dining tent, sleeping quarters, an outhouse, a powerhouse, two runways
(a primary and a back-up runway only for use in case of emergency), and
a helipad. The number of structures and tents would range from 15 to
20, and structures typically would be 2-6 meters (m) by 6-10 m in size.
Some tents may be octagon shaped and approximately 6 m in diameter.
Berthing tents would contain collapsible bunk beds, a heating unit, and
a circulation fan. The completed ice camp, including runway, would be
approximately 1.6 km diameter. Support equipment for the ice camp
includes snowmobiles, snow blowers, gas powered augers and saws (for
boring holes through the ice), two reverse osmosis units, and diesel
generators. Aircraft would be used to transport personnel and equipment
to and from Prudhoe Bay, Alaska, and the ice camp. All ice camp
materials, fuel, and food would be transported from Prudhoe Bay,
Alaska, and would either be air-dropped from military transport
aircraft (e.g., C-17 and C-130) or delivered via small twin-engine
aircraft and military and commercial helicopters to the ice camp
runway. At the completion of ICEX26, the ice camp would be demobilized
and removed, and all personnel would depart.
A portable tracking range for submarine training and testing would
be installed in the vicinity of the ice camp during ICEX26. Hydrophones
would be deployed on the ice by drilling or melting holes in the ice
and lowering the cable down into the water column, and extend to
approximately 30 m below the ice. Hydrophones would be approximately
11.8 centimeters (cm) in length and have 610 m in associated cables.
The hydrophones would be linked remotely to the command hut via cables.
Additionally, tracking pingers would be configured aboard each
submarine to continuously monitor the location of the submarines.
Acoustic communications with the submarines would be used to coordinate
the training and research schedule with the submarines, and an
underwater telephone would be used as a backup to the acoustic
communications. The Navy plans to recover the hydrophones; however, if
emergency demobilization is required or the hydrophones are frozen in
place and are unrecoverable, they would be left in place.
Additional information about the ICEX26 ice camp is located in the
2025 Draft EA/OEA for ICEX26. We have carefully reviewed this
information and determined that activities associated with the ICEX26
ice camp, including de minimis acoustic communications, would not
result in incidental take of marine mammals.
Submarine Training and Testing
Submarine activities associated with ICEX26 would generally entail
safety maneuvers, active sonar use, and exercise torpedo use similar to
submarine activities conducted in other undersea environments. The
safety maneuvers and sonar use are similar to submarine activities
conducted in other undersea environments and are being conducted in the
Arctic to test their performance in a cold environment. The Navy
anticipates the use of no more than 10 exercise torpedoes during
ICEX26. The exercise torpedoes are inert (i.e., non-explosive), and
will be recovered by divers, who enter the water through melted holes,
approximately 1 m wide. Submarine training and testing involves active
acoustic transmissions, which have the potential to harass marine
mammals. The Navy categorizes acoustic sources into ``bins'' based on
frequency, source level, and mode of usage (U.S. Department of the
Navy, 2025b). The acoustic source classification bins do not include
the broadband noise produced incidental to vessel and aircraft transits
and weapons firing. Noise produced from vessel, aircraft, and weapons
firing activities are not carried forward because those activities were
found to have de minimis or no acoustic impacts. The acoustic
transmissions associated with submarine training fall within mid-
frequency (MF; generally 1-10 kilohertz (kHz), source level greater
than 190 decibels (dB)) and high-frequency (HF; generally 10-100 kHz,
source level less than 200 dB) bins as defined in the Navy's Phase IV
at-sea environmental documentation (see the 2025 AFTT Supplemental
Environmental Impact Statement/Overseas Environmental Impact Statement,
available at https://www.nepa.navy.mil/aftteis/). The specifics of
ICEX26 submarine acoustic sources are classified, including the
parameters associated with the designated bins. Details of source use
for submarine training are also classified. Any ICEX-specific acoustic
sources not captured under one of the at-sea bins were modeled using
source-specific parameters.
All non-acoustic components of submarine training and testing
activities are fully analyzed within the 2025 Draft EA/OEA for ICEX26
(found online at https://www.nepa.navy.mil/icex/) and remain unchanged.
We have carefully reviewed and discussed with the Navy these other
aspects, such as vessel use, and determined that aspects of submarine
training and testing other than active acoustic transmissions would not
result in take of marine mammals. These non-acoustic components will
not be discussed further, with the exception of vessel strike or
exercise torpedo strike, which are discussed in the Potential Effects
of Specified Activities on Marine Mammals and their Habitat section.
Research Activities and Scientific Active Acoustic Devices
Personnel and equipment proficiency testing and multiple research
and development activities would be conducted as part of ICEX26. One
UUV would be deployed under the ice to test the communication and range
of the vehicle and to conduct under-ice and in-water column sampling.
Several other acoustic sources (i.e., echosounder, transducers) would
be deployed under the ice or in the water column to determine systems
signal
[[Page 51047]]
recognition capabilities. Testing involving the UUV and various
acoustic/communication sources involve active acoustic transmissions,
which have the potential to harass marine mammals underwater. There are
no on-ice or in-air active acoustic devices proposed for use as part of
ICEX26. Most acoustic transmissions that would be used in ICEX26 for
research activities are considered de minimis. The Navy has defined de
minimis sources as having the following parameters: low source levels,
narrow beams, downward directed transmission, short pulse lengths,
frequencies above (outside) known marine mammal hearing ranges, or some
combination of these factors (U.S. Department of the Navy, 2025b).
Additionally, sources with operating frequencies of 200 kHz or above or
source levels of 160 dB or below are considered de minimis (see the
2025 Draft EA/OEA for ICEX26 at https://www.nepa.navy.mil/icex/). NMFS
reviewed the Navy's analysis and conclusions on de minimis sources and
finds them complete and supportable. Parameters for scientific devices
with active acoustics, including de minimis sources, are included in
table 1. Additional information about ICEX26 research activities is
located in table 1-1 of the Navy's application and table 2-1 of the
2025 Draft EA/OEA for ICEX26, and elsewhere in that document. The
possibility of vessel strikes caused by use of UUVs during ICEX26 is
discussed in the Potential Effects of Vessel Strike section.
Table 1--Parameters for Scientific Devices With Active Acoustics
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Frequency
Research institution Source name range Source Pulse length Source type
(kHz) level (dB)
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University of Washington Seaglider....... 10 185 1 second........ UUV.
Applied Physics Laboratory.
Naval Postgraduate School.... Echosounder..... 38-200 221 0.5 milliseconds Sonar.
Massachusetts Institute of Echosounder..... 0.05-9 180 Variable........ Sonar.
Technology Lincoln Lab.
Massachusetts Institute of SimRad Combi.... 38/200 219/227 Variable........ Transducer.
Technology Lincoln Lab.
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Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).
Description of Marine Mammals in the Area of Specified Activities
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 2 lists all species or stocks for which take is expected 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 serious injury and mortality (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 (Young et al., 2024). All values presented in
table 2 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 2--Species \1\ With Estimated Take From the Specified Activities
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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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Ringed seal......................... Pusa hispida........... Arctic................. T, D, Y UND \5\ \6\ (UND, UND, UND 6,459
2013).
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\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
(https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). 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. A
CV associated with estimated mortality due to commercial fisheries is presented in some cases.
[[Page 51048]]
\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 shorefast 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.
\6\ Boveng et al. (2025) estimated the abundance of ringed seals in the Chukchi Sea as 592,577 animals, which accounted for availability bias and used
aerial survey and telemetry data.
As indicated in table 2, ringed seals (with one managed stock)
temporally and spatially co-occur with the activity to the degree that
take is reasonably likely to occur. While beluga whales (Delphinapterus
leucas), gray whales (Eschrichtius robustus), bowhead whales (Balaena
mysticetus), bearded seals (Erignathus barbatus), and spotted seals
(Phoca largha) may occur in the ICEX Study 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. Bowhead whales are unlikely to occur in the ICEX Study
Area between February and April, as they spend winter (December to
April) in the northern Bering Sea and southern Chukchi Sea, and migrate
north through the Chukchi Sea and Beaufort Sea (both encompassed within
the Arctic Ocean) during April and May (Young et al., 2024). On their
spring migration, the earliest that bowhead whales reach Point Hope in
the Chukchi Sea, well south of Point Barrow, is late March to mid-April
(Braham et al., 1980). Although the ice camp location is not known with
certainty, the distance between Point Barrow and the closest edge of
the Ice Camp Study Area is over 200 km. The distance between Point
Barrow and the closest edge of the Navy Activity Study Area is over 50
km, and the distance between Point Barrow and Point Hope is an
additional 525 km (straight line distance); accordingly, bowhead whales
are unlikely to occur in the ICEX Study Area before ICEX26 activities
conclude. Beluga whales follow a migration pattern similar to bowhead
whales. They typically overwinter in the Bering Sea and migrate north
during the spring to the eastern Beaufort Sea where they spend the
summer and early fall months (Young et al., 2023). Though the beluga
whale migratory path crosses through the ICEX Study Area, they are
unlikely to occur in the ICEX Study Area between February and April. Of
note, the ICEX Study Area does overlap the northernmost portion of the
North Bering Strait, East Chukchi, West Beaufort Sea beluga whale
migratory biologically important area (BIA) (April and May) (Clarke et
al., 2023), though the data support for this BIA is low, the boundary
certainty is low, and the importance score is moderate. Given the
spring migratory direction, the northernmost portion of the BIA is
likely more important later in the April and May period, and overlap
with this BIA does not imply that belugas are likely to be in the ICEX
Study Area during the Navy's activities.
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., 2021).
Typically, northward migrating gray whales do not reach the Bering Sea
before May or June (Frost and Karpovich, 2008), after the ICEX26
activities would occur, and several hundred kilometers south of the
ICEX Study Area. Further, gray whales are primarily bottom feeders
(Swartz et al., 2006) in water less than 60 m deep (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. Therefore, gray whales are not
expected to occur in the ICEX Study Area during the ICEX26 activity
period.
Bearded seals may occur in the ICEX Study Area during the project
timeframe but NMFS does not expect they would occur in the areas near
the ice camp or where submarine activities involving active acoustics
would occur. The Navy anticipates the ice camp would be established
185-370 km north of Prudhoe Bay in water depths of 800 m or more, and
submarine training and testing activities would occur in water depths
of 800 m or more. Although acoustic data indicate some bearded seals
remain in the Beaufort Sea year-round (MacIntyre et al., 2013; Jones et
al., 2014; MacIntyre et al., 2015), satellite tagging data (Boveng and
Cameron, 2013; Alaska Department of Fish and Game, 2021) show that
large numbers of bearded seals move south in fall/winter with the
advancing ice edge to spend the winter in the Bering Sea, confirming
previous visual observations (Burns and Frost, 1979; Cameron and
Boveng, 2009; Frost and Karpovich, 2008). The southward movement of
bearded seals in the fall means that very few individuals are expected
to occur along the Beaufort Sea continental shelf in February through
April, the timeframe for ICEX26 activities. The northward spring
migration through the Bering Strait, begins in mid-April (Burns and
Frost, 1979).
In the event some bearded seals were to remain in the Beaufort Sea
during the season when ICEX26 activities would occur, the most probable
area in which bearded seals might occur during winter months is along
the continental shelf. Bearded seals feed extensively on benthic
invertebrates (e.g., clams, gastropods, crabs, shrimp, bottom-dwelling
fish) (Cameron et al., 2010; Quakenbush et al., 2011) and are typically
found in water depths of 200 m or less (Burns, 1970). The Bureau of
Ocean Energy Management conducted an aerial survey from July through
October that covered the shallow Beaufort and Chukchi Sea shelf waters
and observed bearded seals from Icy Cape to the border of Canada
(Clarke et al., 2017). The farthest from shore that bearded seals were
observed was the waters of the continental slope (though this study was
conducted outside of the ICEX26 time frame). As mentioned previously,
the Navy anticipates the ice camp would be established 185-370 km north
of Prudhoe Bay in water depths of 800 m or more. The continental shelf
near Prudhoe Bay is approximately 100 km wide; therefore, even if the
ice camp were established at the closest estimated distance (185 km
from Prudhoe Bay), it would still be approximately 83 km from habitat
potentially occupied by bearded seals. Empirical evidence has not shown
responses to sonar that would constitute take beyond a few kilometers
from an acoustic source, and therefore, NMFS and the Navy set a
distance cutoff of 5 km. Regardless of the source level at that
distance, take is not estimated to occur beyond 5 km from the source.
Although bearded seals occur 37-185 km offshore during spring (Bengtson
et al., 2005; Simpkins et al., 2003), they feed heavily on benthic
organisms (Fedoseev, 1965; Hamilton et al., 2018; Hjelset et al.,
1999), and during winter bearded seals are expected to select habitats
where food is abundant and easily accessible to minimize the energy
required to forage and maximize energy reserves in preparation for
whelping, lactation, mating, and molting. Bearded seals are not known
to dive as deep as 800 m to forage, with adults typically diving no
more than 100 m deep, though first year pups may dive to depths greater
than
[[Page 51049]]
450 m (Boveng and Cameron, 2013; Cameron et al., 2010; Cameron and
Boveng, 2009; Gjertz et al., 2000; Kovacs, 2009), and it is highly
unlikely they would occur near the ice camp or where the submarine
activities would be conducted. This conclusion is supported by the fact
that the Navy did not visually observe or acoustically detect bearded
seals during the 2020, 2022, or 2024 ice exercises.
Spotted seals may also occur in the ICEX26 Study Area during summer
and fall, but they are not expected to occur in the ICEX26 Study Area
during the ICEX26 timeframe (Young et al., 2024).
In addition, the polar bear (Ursus maritimus) may be found in
ICEX26 Study Area. However, polar bears are managed by the U.S. Fish
and Wildlife Service and are not considered further in this document.
Ringed Seal
Ringed seals are the most common pinniped in the ICEX26 Study Area
and have wide distribution in seasonally and permanently ice-covered
waters of the Northern Hemisphere (North Atlantic Marine Mammal
Commission, 2004), though the status of the Arctic stock of ringed
seals is unknown (Young et al., 2024). 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, 1988b). 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). Breathing holes are maintained by ringed seals' sharp teeth and
claws 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., 2024).
Ringed seals have at least two distinct types of subnivean lairs:
haul-out 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 land-fast ice as well as stable
pack ice. Lentfer (1972) found that ringed seals north of Barrow,
Alaska (which would be west of the ice camp), build their subnivean
lairs on the pack ice near pressure ridges. They are also assumed to
occur within the sea ice in the proposed ice camp area. 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). Lindsay et al. (2021) found ringed seal counts
increased after mid-May and pup counts increased after the end of
April. Snow depths of at least 50-65 cm are required for functional
birth lairs (Kelly, 1988a; Lydersen, 1998; Lydersen and Gjertz, 1986;
Smith and Stirling, 1975), and such depths typically occur only where
20-30 cm or more of snow has accumulated on flat ice and then drifted
along pressure ridges or ice hummocks (Hammill, 2008; Lydersen et al.,
1990;, Lydersen and Ryg, 1991; Smith and Lydersen, 1991). Ringed seal
birthing season typically begins 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 maximal extent, ringed seals are abundant in the northern Bering
Sea, Norton and Kotzebue Sounds, and throughout the Chukchi and
Beaufort Seas (Boveng et al., 2025; Frost, 1985; Kelly, 1988b),
including in the ICEX26 Study Area. Passive acoustic monitoring (PAM)
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 Barrow,
Alaska, detected ringed seals in the area between mid- December and
late May over a 4-year study (Jones et al., 2014). With the onset of
the fall freeze, ringed seal movements become increasingly 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
remain in the Beaufort Sea (Crawford et al., 2012; Frost and Lowry,
1984; Harwood et al., 2012). Kelly et al. (2010a) tracked home ranges
for ringed seals in the subnivean period (using shorefast ice); the
size of the home ranges varied from less than 1 km\2\ up to 27.9 km\2\
(median of 0.62 km\2\ for adult males and 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., 2010a). 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., 2010a). 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). Ringed seals may occur within the ICEX26 Study Area
throughout the year and during the proposed specified activities.
Critical habitat for the ringed seal was designated in May 2022 and
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 the ringed seal 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 landfast
(shorefast) ice or dense, stable pack ice, which have undergone
deformation and contain snowdrifts of sufficient depth to form and
maintain birth lairs (typically at least 54 cm 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 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 proposed ice camp study area was excluded from the ringed seal
critical habitat because the benefits of exclusion due to national
security impacts outweighed the benefits of inclusion of this area (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 proposed for
exclusion contains one or more of the essential features of the Arctic
ringed seal's critical habitat, although data are limited to inform
NMFS' assessment of the relative value of this area to the conservation
of the species. As noted above, a portion of the ringed seal critical
habitat overlaps the larger proposed ICEX26 Study Area. Notwithstanding
an earlier court decision vacating NMFS' critical habitat designation
for ringed seals, the underlying information regarding the importance
of the area and associated features to ringed seals and their habitat
remains relevant to the discussion here. However, as described later
and in more
[[Page 51050]]
detail in the Potential Effects of Specified Activities on Marine
Mammals and their Habitat section, we do not anticipate physical
impacts to any marine mammal habitat as a result of the Navy's ICEX
activities, including impacts to ringed seal sea ice habitat suitable
as a platform for basking and molting and impacts on prey availability.
Further, this proposed IHA includes mitigation measures, as described
in the Proposed Mitigation section, which would minimize or prevent
impacts to sea ice habitat suitable for the formation and maintenance
of subnivean birth lairs.
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., Au and Hastings, 2008; Richardson et al.,
1995; Wartzok and Ketten, 1999). 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 ~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 3.
Table 3--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 Activities on Marine Mammals and Their
Habitat
This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals section later in this document
includes a quantitative analysis of the number of individuals that are
expected to be taken by this activity. The Negligible Impact 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.
The Navy has requested authorization for the take of marine mammals
that may occur incidental to ICEX26 activities in the ICEX Study Area.
The Navy 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 sonar use. The effects of
underwater noise from the Navy's proposed activities have the potential
to result in take by Level B harassment of ringed seals in the ICEX
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 activities may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
[[Page 51051]]
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). 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.
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; ISO, 2016; NIOSH, 1998) and
occur either as isolated events or repeated in some succession.
Impulsive sounds are all characterized by a relatively rapid rise from
ambient pressure to a maximal pressure value followed by a rapid decay
period that may include a period of diminishing, oscillating maximal
and minimal pressures, and generally have an increased capacity to
induce physical injury as compared with sounds that lack these
features. There are no pulsed sound sources associated with any
proposed ICEX26 activities.
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 sonar
sources (such as those proposed for use by the Navy as part of the
proposed ICEX26 activities) that intentionally direct a sound signal at
a target that is reflected back in order to discern physical details
about the target.
Modern sonar technology includes a variety of sonar sensor and
processing systems. In concept, the simplest active sonar emits sound
waves, or ``pings,'' sent out in multiple directions, and the sound
waves then reflect off of the target object in multiple directions. The
sonar source calculates the time it takes for the reflected sound waves
to return; this calculation determines the distance to the target
object. More sophisticated active sonar systems emit a ping and then
rapidly scan or listen to the sound waves in a specific area. This
provides both distance to the target and directional information. Even
more advanced sonar systems use multiple receivers to listen to echoes
from several directions simultaneously and provide efficient detection
of both direction and distance. In general, when sonar is in use, the
sonar `pings' occur at intervals, referred to as a duty cycle, and the
signals themselves are very short in duration. For example, sonar that
emits a 1-second ping every 10 seconds has a 10 percent duty cycle. The
Navy's most powerful hull-mounted mid-frequency sonar source used in
ICEX activities typically emits a 1-second ping every 50 seconds
representing a 2 percent duty cycle. The Navy utilizes sonar systems
and other acoustic sensors in support of a variety of mission
requirements.
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 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 levels for marine mammals are estimates, as with the exception of a
single study unintentionally inducing
[[Page 51052]]
PTS in a harbor seal (Phoca vitulina) (Kastak et al., 2008), 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
(SELcum) in an accelerating fashion: at low exposures with
lower SELcum, the amount of TTS is typically small and the
growth curves have shallow slopes. At exposures with higher
SELcum, 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) and Southall et al. (2019) 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 strong 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). 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 SEL (Finneran et al., 2010; Kastelein et al.,
2014; Mooney et al., 2009). This means that TTS predictions based on
the total, cumulative SEL will overestimate the amount of TTS from
intermittent exposures, such as sonars and impulsive sources.
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 is no PTS data for cetaceans, but
such relationships are assumed to be similar to those in humans and
other terrestrial
[[Page 51053]]
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 pulses as received close to the
source) are at least 6 dB higher than the TTS threshold on a peak-
pressure basis and AUD INJ SELcum thresholds are 15 to 20 dB
higher than TTS SELcum 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 [mu]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 [mu]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 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
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
[[Page 51054]]
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 activities), 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).
Seals exposed to non-impulsive sources with a received sound
pressure level within the range of calculated exposures for ICEX26
activities (142-193 dB re 1 [mu]Pa), have been shown to change their
behavior by modifying diving activity and avoidance of the sound source
(G[ouml]tz et al., 2010; Kvadsheim et al., 2010). Although a minor
change to a behavior may occur as a result of exposure to the sources
in the proposed specified activities, these changes would be within the
normal range of behaviors for the animal (e.g., the use of a breathing
hole further from the source, rather than one closer to the source,
would be within the normal range of behavior) (Kelly, 1988a).
Adult ringed seals spend up to 20 percent of the time in subnivean
lairs during the winter season (Kelly et al., 2010a). 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 haulout 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). 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, according to Kelly et al.
(1988), in all instances in which observed seals departed lairs in
response to noise disturbance, they subsequently reoccupied the lair.
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 (Smith, 1987). 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 Hammill, 1981; Smith and Stirling, 1975). The
acoustic sources from these proposed specified activities 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., 1992a).
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.
Responses Due to Sonar and Other Transducers--
Pinniped behavioral response to sonar and other transducers is
context-dependent (e.g., Hastie et al., 2014; Southall et al., 2019).
All studies on pinniped response to sonar thus far have been limited to
captive animals, though, based on exposures of wild pinnipeds to vessel
noise and impulsive sounds, pinnipeds may only respond strongly to
military sonar that is in close proximity or approaching an animal.
Kvadsheim et al. (2010) found that captive hooded seals exhibited
avoidance response to sonar signals between 1-7 kHz (160-170 dB re 1
[mu]Pa RMS) by reducing diving activity, rapid surface swimming away
from the source, and eventually moving to areas of least SPL. However,
the authors noted a rapid adaptation in behavior (passive surface
floating) during the second and subsequent exposures, indicating a
level of habituation within a short amount of time. Kastelein et al.
(2015) exposed captive harbor seals to three different sonar signals at
25 kHz with variable waveform characteristics and duty cycles and found
individuals responded to a frequency modulated signal at received
levels over 137 dB re 1 [mu]Pa by hauling out more, swimming faster,
and raising their heads or jumping out of the water. However, seals did
not respond to a continuous wave or combination signals at any received
level (up to 156 dB re 1 [mu]Pa). Houser et al. (2013) conducted a
study to determine behavioral responses of captive California sea lions
to mid-frequency active sonar at various received levels (125-185 dB re
1 [mu]Pa). They found younger animals (less than 2 years old) were more
likely to respond than older animals and responses included increased
respiration rate, increased time spent submerged, refusal to
[[Page 51055]]
participate in a repetitive task, and hauling out. Most responses below
155 dB re 1 [mu]Pa were changes in respiration, while more severe
responses (i.e., refusing to participate, hauling out) began to occur
over 170 dB re 1 [mu]Pa, and many of the most severe responses came
from the young sea lions.
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, 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.
Richardson et al. (1995) argued that the maximum radius of
influence of anthropogenic noise (including broadband low-frequency
sound transmission) on a marine mammal is the distance from the source
to the point at which the noise can barely be heard. This range is
determined by either the hearing sensitivity (including critical
ratios, or the lowest signal-to-noise ratio in which animals can detect
a signal) of the animal (Finneran and Branstetter, 2013; Johnson et
al., 1989; Southall et al., 2000) or the background noise level
present. Masking is most likely to affect some species' ability to
detect communication calls and natural sounds (i.e., surf noise, prey
noise, etc.) (Richardson et al., 1995).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009; Matthews et al., 2016) and may result in energetic
or other costs as animals change their vocalization behavior (e.g., 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).
High-frequency sounds may mask the echolocation calls of toothed
whales. Human data indicate low-frequency sound can mask high-frequency
sounds (i.e., upward masking). Studies on captive odontocetes by Au et
al. (1974), Au et al. (1985), and Au (1993) indicate that some species
may use various processes to reduce masking effects (e.g., adjustments
in echolocation call intensity or frequency as a function of background
noise conditions). Odontocete hearing is highly directional at high
frequencies, facilitating echolocation in masked conditions (Au and
Moore, 1984). A study by Nachtigall et al. (2018) showed that false
killer whales adjust their hearing to compensate for ambient sounds and
the intensity of returning echolocation signals.
Impacts on signal detection, measured by masked detection
thresholds, are not the only important factors to address when
considering the potential effects of masking. As marine mammals use
sound to recognize conspecifics, prey, predators, or other biologically
significant sources (Branstetter et al., 2016), it is also important to
understand the impacts of masked recognition thresholds (i.e.,
informational masking). Branstetter et al. (2016) measured masked
recognition thresholds for whistle-like sounds of bottlenose dolphins
and observed that they are approximately 4 dB above detection
thresholds (energetic masking) for the same signals. Reduced ability to
recognize a conspecific call or the acoustic signature of a predator
could have severe negative impacts. Branstetter et al. (2016) observed
that if ``quality communication'' is set at 90 percent recognition the
output of communication space models (which are based on 50 percent
detection) would likely result in a significant decrease in
communication range. As marine mammals use sound to
[[Page 51056]]
recognize predators (Allen et al., 2014; Cummings and Thompson, 1971;
Cur[eacute] et al., 2015; Fish and Vania, 1971), the presence of
masking noise may also prevent marine mammals from responding to
acoustic cues produced by their predators, particularly if it occurs in
the same frequency band. For example, harbor seals that reside in the
coastal waters of British Columbia are frequently targeted by mammal-
eating killer whales. The seals acoustically discriminate between the
calls of mammal-eating and fish-eating killer whales (Deecke et al.,
2002), a capability that should increase survivorship while reducing
the energy required to identify all killer whale calls. Similarly,
sperm whales (Cur[eacute] et al., 2016; Isojunno et al., 2016), long-
finned pilot whales (Visser et al., 2016), and humpback whales
(Cur[eacute] et al., 2015) changed their behavior in response to killer
whale vocalization playbacks. The potential effects of masked predator
acoustic cues depend on the duration of the masking noise and the
likelihood of a marine mammal encountering a predator during the time
that detection and recognition of predator cues are impeded.
Redundancy and context can also facilitate detection of weak
signals. These phenomena may help marine mammals detect weak sounds in
the presence of natural or anthropogenic noise. Most masking studies in
marine mammals present the test signal and the masking noise from the
same direction. The dominant background noise may be highly directional
if it comes from a particular anthropogenic source such as a vessel or
industrial site. Directional hearing may significantly reduce the
masking effects of these sounds by improving the effective signal-to-
noise ratio.
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most of the increase from distant commercial shipping
(Cholewiak et al., 2018; Hildebrand et al., 2009). All anthropogenic
sound sources, but especially chronic and lower-frequency signals
(e.g., from commercial vessel traffic), contribute to elevated ambient
sound levels, thus intensifying masking for marine mammals.
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 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). However, it should be noted that our
understanding of the functions of various stress hormones (e.g.,
cortisol), is based largely upon observations of the stress response in
terrestrial mammals. Atkinson et al. (2015) note that the endocrine
response of marine mammals to stress may not be the same as that of
terrestrial mammals because of the selective pressures marine mammals
faced during their evolution in an ocean environment. For example, due
to the necessity of breath-
[[Page 51057]]
holding while diving and foraging at depth, the physiological role of
epinephrine and norepinephrine (the catecholamines) in marine mammals
might be different than in other mammals. Relatively little information
exists on the linkage between anthropogenic sound exposure and stress
in marine mammals, and even less information exists on the ultimate
consequences of sound-induced stress responses (either acute or
chronic). Most studies to date have focused on acute responses to sound
either by measuring catecholamines, a neurohormone, or heart rate as a
proxy for an acute stress response.
The ability to make predictions from stress hormones about impacts
on individuals and populations exposed to various forms of natural and
anthropogenic stressors relies on understanding the linkages between
changes in stress hormones and resulting physiological impacts.
Currently, the sound characteristics that correlate with specific
stress responses in marine mammals are poorly understood, as are the
ultimate consequences of these changes. Several research efforts have
improved the understanding of, and the ability to predict, how
stressors ultimately affect marine mammal populations (e.g., King et
al., 2015; New et al., 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.
Potential Effects on Marine Mammal Habitat
The Navy'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 ICEX Study Area.
Potential Effects of Sonar on Prey
Ringed seals feed on marine invertebrates and fish. Marine
invertebrates occur in the world's oceans, from warm shallow waters to
cold deep waters, and are the dominant animals in all habitats of the
ICEX Study Area. Although most species are found within the benthic
zone, marine invertebrates 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). In a review of crustacean sensitivity of high amplitude
underwater noise by Edmonds et al. (2016), crustaceans may be able to
hear the frequencies at which they produce sound, but it remains
unclear which noises are incidentally produced and if there are any
negative effects from masking them. 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 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).
It is expected that most marine invertebrates would not sense the
frequencies of the sonar associated with the proposed specified
activities. Most marine invertebrates would not be close enough to
active sonar systems to potentially experience impacts to sensory
structures. Any marine invertebrate capable of sensing sound may alter
its behavior if exposed to sonar. Although acoustic transmissions
produced during the proposed specified activities may briefly impact
individuals, intermittent exposures to sonar are not expected to impact
survival, growth, recruitment, or reproduction of widespread marine
invertebrate populations.
The fish species located in the ICEX 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
[[Page 51058]]
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 ICEX Study Area are expected to hear the low-
frequency sources associated with the proposed specified activities,
but most are not expected to detect the higher-frequency sounds. Only a
few fish species are able to detect mid-frequency sonar above 1 kHz and
could have behavioral reactions or experience auditory masking during
these activities. These effects are expected to be transient, and long-
term consequences for the population are not expected. Fish with
hearing specializations capable of detecting high-frequency sounds are
not expected to be within the ICEX Study Area. If hearing specialists
were present, they would have to be in close vicinity to the source to
experience effects from the acoustic transmission. 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 comes into contact
with 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 ICEX26 active sonar sources would be
localized, temporary, and infrequent.
Effects of Acoustics on Physical and Foraging Habitat
Unless the sound source is stationary and/or continuous over a long
duration in one area, neither of which applies to ICEX26 activities,
the effects of the introduction of sound into the environment are
generally considered to have a less severe impact on marine mammal
habitat compared to any physical alteration of the habitat. Acoustic
exposures are not expected to result in long-term physical alteration
of the water column or bottom topography as the occurrences are of
limited duration and would occur intermittently. 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. For these reasons, it is unlikely that the Navy's
acoustic activities in the ICEX Study Area would have any effect on
marine mammal habitat.
Potential Effects of Vessel Strike
Because ICEX26 would occur only when there is ice coverage and
conditions are appropriate to establish an ice camp on an ice floe, no
ships or smaller boats would be involved in the activity. Vessel use
would be limited to submarines and UUVs (hereafter referred to together
as ``vessels'' unless noted separately). The potential for vessel
strike during ICEX26 would therefore only arise from the use of
submarines during training and testing activities, and the use of UUVs
during research activities. Depths at which vessels would operate
during ICEX26 would overlap with known dive depths of ringed seals,
which have been recorded to 300 m in depth (Gjertz et al., 2000;
Lydersen and Ryg, 1991). Few authors have specifically described the
responses of pinnipeds to vessels, and most of the available
information on reactions to boats concerns pinnipeds hauled out on land
or ice. No information is available on potential responses to
submarines or UUVs. Brueggeman et al. (1992) stated ringed seals hauled
out on the ice showed short-term escape reactions when they were within
0.25-0.5 km from a vessel; ringed seals would likely show similar
reactions to submarines and UUVs, decreasing the likelihood of vessel
strike during ICEX26 activities.
The Navy has kept strike records for over 20 years and has no
records of individual pinnipeds being struck by a vessel as a result of
Navy activities and, further, the smaller size and maneuverability of
pinnipeds make a vessel strike unlikely. Also, NMFS has never received
any reports indicating that pinnipeds have been struck by vessels of
any type. Review of additional sources of information in the form of
worldwide vessel strike records shows little evidence of strikes of
pinnipeds from the shipping sector. Further, a review of seal stranding
data from Alaska found that during 2020, nine ringed seal strandings
were recorded by the Alaska Marine Mammal Stranding Network. Within the
Arctic region of Alaska, seven ringed seal strandings were recorded. Of
the nine strandings reported in Alaska (all regions included), none
were found to be caused by vessel collisions (Savage, 2021).
Vessel speed, size, and mass are all important factors in
determining both the potential likelihood and impacts of a vessel
strike to marine mammals (Blondin et al., 2025; Conn and Silber, 2013;
Garrison et al., 2025; Gende et al., 2011; Silber et al., 2010;
Vanderlaan and Taggart, 2007; Wiley et al., 2016). When
[[Page 51059]]
submerged, submarines are generally slow moving (to avoid detection)
and therefore marine mammals at depth with a submarine are likely able
to avoid collision with the submarine. For most of the research and
training and testing activities during the specified activity,
submarine and UUV speeds would not typically exceed 18.5 km/hr during
the time spent within the ICEX Study Area, which would lessen the
already extremely unlikely chance of collisions with marine mammals,
specifically ringed seals.
Based on consideration of all this information, NMFS does not
anticipate incidental take of marine mammals by vessel strike from
submarines or UUVs.
Potential Effects of Exercise Torpedo Strike
As noted in the Detailed Description of Specific Activity section,
the Navy may use inert exercise torpedoes in ICEX26. While the details
of the proposed torpedo exercises are classified, given the limited
potential number of exercise torpedoes deployed (maximum of 10) during
the exercise window, and the low density of ringed seals in the ICEX
Study Area during this time, NMFS does not anticipate incidental take
of marine mammals by exercise torpedo strike.
Potential Non-Acoustic Impacts
Deployment of the ice camp could potentially affect ringed seal
habitat by physically damaging or crushing subnivean lairs, which could
potentially result in ringed seal injury or mortality. March 1 is
generally expected to be the onset of ice seal lairing season, and
ringed seals typically construct lairs near pressure ridges. As
described in the Proposed Mitigation section, the ice camp and runway
would be established on a combination of first-year ice and multi-year
ice without pressure ridges, which would minimize the possibility of
physical impacts to subnivean lairs and habitat suitable for lairs. Ice
camp deployment would begin mid-February, and be gradual, with activity
increasing over the first 5 days. So, in addition, this schedule would
discourage seals from establishing birthing lairs in or near the ice
camp, and would allow ringed seals to relocate outside of the ice camp
area as needed, though both scenarios are unlikely as described below
in this section. Personnel on on-ice vehicles would observe for marine
mammals, and would follow established routes when available, to avoid
potential disturbance of lairs and habitat suitable for lairs.
Personnel on foot and operating on-ice vehicles would avoid deep snow
drifts near pressure ridges, also to avoid potential lairs and habitat
suitable for lairs. Implementation of these measures are expected to
prevent ringed seal lairs from being crushed or damaged during ICEX26
activities and are expected to minimize any other potential impacts to
sea ice habitat suitable for the formation of lairs. Given the proposed
mitigation requirements, we also do not anticipate ringed seal injury
or mortality as a result of damage to subnivean lairs.
ICEX26 personnel would be actively conducting testing and training
operations on the sea ice and would travel around the camp area,
including the runway, on snowmobiles. Although the Navy does not
anticipate observing any seals on the ice given the lack of
observations during previous ice exercises (U.S. Department of the
Navy, 2018; U.S. Department of the Navy, 2020; U.S. Department of the
Navy, 2022; U.S. Department of the Navy, 2025a), as a general matter,
on-ice activities could cause a seal that would have otherwise built a
lair in the area of an activity to be displaced and therefore,
construct a lair in a different area outside of an activity area, or a
seal could choose to relocate to a different existing lair outside of
an activity area. However, in the case of the ice camp associated with
ICEX26, displacement of seal lair construction or relocation to
existing lairs outside of the ice camp area is unlikely, given the low
average density of structures (the average ringed seal ice structure
density in the vicinity of Prudhoe Bay, Alaska is 1.58 structures per
km\2\ (table 4)), the relative footprint of the Navy's planned ice camp
(2 km\2\), the lack of previous ringed seal observations on the ice
during ICEX activities, and proposed mitigation requirements that would
require the Navy to construct the ice camp and runway on first-year or
multiyear ice without pressure ridges and would require personnel to
avoid areas of deep snow drift or pressure ridges (see the Proposed
Mitigation section for additional information about the proposed
mitigation requirements). This measure, in combination with the other
mitigation measures required for operation of the ice camp are expected
to avoid impacts to the construction and use of ringed seal subnivean
lairs, particularly given the already low average density of lairs, as
described above.
Table 4--Ringed Seal Ice Structure Density in the Vicinity of the
Prudhoe Bay, Alaska
------------------------------------------------------------------------
Ice structure density
Year (structures per km\2\) Source
------------------------------------------------------------------------
1982......................... 3.6 Frost and Burns
(1989).
1983......................... 0.81 Kelly et al.
(1986).
1999......................... 0.71 Williams et al.
(2001).
2000......................... 1.2 Williams et al.
(2001).
Average Density.............. 1.58
------------------------------------------------------------------------
Given the required mitigation measures and the low density of
ringed seals anticipated in the Ice Camp Study Area during ICEX26, we
do not anticipate behavioral disturbance of ringed seals due to human
presence.
The Navy's activities would occur prior to the late spring to early
summer ``basking period,'' which occurs between abandonment of the
subnivean lairs and melting of the seasonal sea ice, and is when the
seals undergo their annual molt (Kelly et al., 2010b). Given that the
ice camp would be demobilized prior to the basking period, and the
remainder of the Navy's activities occur below the sea ice, impacts to
sea ice habitat suitable as a platform for basking and molting are not
anticipated to result from the ICEX26 activities.
Our preliminary determination of potential effects to the physical
environment includes minimal possible impacts to marine mammals and
their habitat from camp operation or deployment activities, given the
proposed mitigation and the timing of the Navy's proposed activities.
In addition, given the relatively short duration of submarine testing
and training activities, the relatively small area that would be
affected, and the lack of impacts to physical or foraging habitat, the
proposed specified activities are not likely to have an adverse effect
on prey species or marine mammal
[[Page 51060]]
habitat, other than potential localized, temporary, and infrequent
effects to fish as discussed above. Therefore, any impacts to ringed
seals and their habitat, as discussed above in this section, are not
expected to cause significant or long-term consequences for individual
ringed seals or the population. Please see the Negligible Impact
Analysis and Determination section for additional discussion regarding
the likely impacts of the Navy's activities on ringed seals, including
the reproductive success or survivorship of individual ringed seals,
and how those impacts on individuals are likely to impact the species
or stock.
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 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 responses and/or TTS for individual marine mammals
resulting from exposure to acoustic transmissions. 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, have been recently updated (NMFS,
2024) as reflected below in the Level A harassment section.
Level B Harassment
In coordination with NMFS, the Navy developed behavioral thresholds
to support environmental analyses for the Navy's training and testing
activities utilizing active sonar sources; these behavioral harassment
thresholds are used here to evaluate the potential effects of the
active sonar components of the proposed activities. 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 (Ellison
et al., 2012; Southall et al., 2007; Southall et al., 2021).
The Navy's Phase IV pinniped behavioral criteria is based on
controlled exposure experiments on the following captive animals:
hooded seal, harbor seal, and California sea lion (Houser et al., 2013;
Kastelein et al., 2015; Kvadsheim et al., 2010). Overall exposure
levels were 110-170 dB re 1 [mu]Pa for hooded seals, 107-160 dB re 1
[mu]Pa for harbor seals, and 125-185 dB re 1 [mu]Pa for California sea
lions. Responses occurred at received levels ranging from 107-185 dB re
1 [mu]Pa. However, the mean of the response data was 154 dB re 1
[mu]Pa. Hooded seals were exposed to increasing levels of sonar until
an avoidance response was observed. The harbor seals were exposed to a
variety of contexts, frequencies, and received levels. Each individual
California sea lion was exposed to the same received level 10 times;
these exposure sessions were combined into a single response value,
with an overall response assumed if an animal responded in any single
session.
Based on the Navy's pinniped behavioral response function (see
figure 6-1 of the application), there is a 50 percent probability of
response at 156 dB re 1 [mu]Pa. To account for proximity to the active
acoustic source and based on the best scientific information, a
distance of 5 km is used beyond which exposures would not qualify as
take by Level B harassment under the military readiness definition.
Level A Harassment
NMFS' Updated Technical Guidance for Assessing the Effects of
Anthropogenic Sound on Marine Mammal Hearing (Version 3.0) (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). The Navy's proposed activity
includes the use of non-impulsive (active sonar) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in table 5 below for phocid pinnipeds
underwater. 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.
[[Page 51061]]
Table 5--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ onset acoustic thresholds * (received level)
Hearing group ----------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Phocid Pinnipeds (PW) (Underwater)....... Lpk,flat: 223 dB; LE,PW,24h: LE,PW,24h: 195 dB.
183 dB.
----------------------------------------------------------------------------------------------------------------
* 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 [mu]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [mu]Pa\2\s. In this table, criteria are abbreviated to be
more reflective of International Organization for Standardization standards (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
(PW 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.
For previous ICEX activities, the Navy's PTS/TTS analysis began
with mathematical modeling to predict the sound transmission patterns
from Navy sources, including sonar. These data were then coupled with
marine species distribution and abundance data to determine the sound
levels likely to be received by various marine species. These criteria
and thresholds were applied to estimate specific effects that animals
exposed to Navy-generated sound may experience. For weighting function
derivation, the most critical data required were TTS onset exposure
levels as a function of exposure frequency. These values can be
estimated from published literature by examining TTS as a function of
sound exposure level (SEL) for various frequencies.
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations.
The Navy performed a quantitative analysis to estimate the number
of mammals that could be harassed by the underwater acoustic
transmissions during the specified activity. The only marine mammal
susceptible to impacts from acoustic transmissions associated with the
proposed activities would be ringed seals.
Ringed seal presence in the ICEX Study Area was obtained using
sighting data from the Ocean Biodiversity Information System-Spatial
Ecological Analysis of Megavertebrate Populations (OBIS-SEAMAP) (Halpin
et al., 2009). The ICEX Study Area was overlaid on the OBIS-SEAMAP
ringed seal sightings map that included sightings from the years 2000-
2007 and the year 2013. Sighting data were only available for the mid
to late summer and fall months. To date, there have been no surveys to
determine ringed seal presence in the Study Area during winter and
spring months.
It is assumed that during the fall most ringed seals would migrate
south and west from the Beaufort Sea to the Bering and Chukchi Seas,
with some ringed seals remaining in the Beaufort Sea. Additionally,
some ringed seals would create subnivean lairs on landfast (shorefast)
ice over the continental shelf during the winter and spring months, and
move back into the Chukchi and Beaufort Seas during the summer and fall
months (Crawford et al., 2012; Frost and Lowry, 1984; Harwood et al.,
2012; Young et al., 2024). Therefore, the average number of individual
ringed seals per year was assumed to be present in the ICEX Study Area
during the proposed activities, regardless of the time of year that the
sighting occurred. Based on the sightings data, it is assumed that
three ringed seals would be present in the ICEX Study Area.
Take Estimation
Here we 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.
When sound sources are active, exposure to increased SPLs would
likely involve individuals that are moving through the area during
foraging trips. Ringed seals also may be exposed en route to haul out
sites or subnivean lairs. If exposure were to occur, the pinnipeds
could exhibit behavioral responses, such as avoidance, increased
swimming speeds, increased surfacing time, or decreased foraging. Most
likely, individuals affected by acoustic transmissions resulting from
the proposed activities would move away from the sound source. Ringed
seals may be temporarily displaced from their subnivean lairs within
the Ice Camp Study Area. Any pinniped would have to be within 5 km of
the source for any behavioral reaction (e.g., flushing from a lair).
Any effects experienced by individual pinnipeds are anticipated to be
limited to short-term disturbance of normal behavior, temporary
displacement or disruption of animals that may occur near the proposed
activity.
Navy estimated that three ringed seals may be taken by Level B
harassment per day of activity within the ICEX Study Area. Navy
anticipates conducting active acoustic transmissions on 42 days, and
therefore requested 126 takes by Level B harassment of ringed seals (3
seals per day x 42 days = 126 takes by Level B harassment) (table 6).
NMFS concurs and proposes to authorize 126 takes by Level B harassment.
All takes are classified as Level B harassment and not further
distinguished because the method used to estimate take does not support
the differentiation between behavioral harassment or TTS.
Modeling for three previous ICEXs (2018, 2020, and 2022), which
employed similar acoustic sources, did not result in any estimated
takes by PTS; therefore, particularly in consideration of the fact that
total takes were likely overestimated for those ICEX activities given
the density information used in the analyses (NMFS anticipates that the
density of ringed seals is actually much lower than estimated in those
analyses) and the similarity between those activities and the
activities proposed for ICEX26, the Navy did not request, and NMFS is
not proposing to authorize, take by Level A harassment of ringed seal.
[[Page 51062]]
Table 6--Estimated Take of Marine Mammals From the Specified Activities
----------------------------------------------------------------------------------------------------------------
Instances of take as a
Species Level B harassment Level A harassment percentage of population
----------------------------------------------------------------------------------------------------------------
Ringed seal............................. 126 0 <1
----------------------------------------------------------------------------------------------------------------
During monitoring for the 2018 IHA covering similar military
readiness activities in the ICEX26 Study Area, the Navy did not
visually observe or acoustically detect any marine mammals (U.S.
Department of the Navy, 2018). During monitoring for the 2020 IHA
covering similar military readiness activities in the ICEX26 Study
Area, the Navy also did not visually observe any marine mammals (U.S.
Department of the Navy, 2020). Acoustic monitoring associated with the
2020 IHA did not detect any discernible marine mammal vocalizations
(Henderson et al., 2021). The monitoring report states that ``there
were a few very faint sounds that could have been (ringed seal) barks
or yelps.'' However, these were likely not from ringed seals, given
that ringed seal vocalizations are generally produced in series (Jones
et al., 2014). Henderson et al. (2021) expect that these sounds were
likely ice-associated or perhaps anthropogenic. While the distance at
which ringed seals could be acoustically detected is not definitive,
Henderson et al. (2021) states that Expendable Mobile ASW Training
Targets (EMATTs) ``traveled a distance of 10 nmi (18.5 km) away and
were detected the duration of the recordings; although ringed seal
vocalization source levels are likely far lower than the sounds emitted
by the EMATTs, this gives some idea of the potential detection radius
for the cryophone. The periods when the surface anthropogenic activity
is occurring in close proximity to the cryophone are dominated by those
broadband noises due to the shallow hydrophone placement in ice (only
10 cm down), and any ringed seal vocalizations that were underwater
could have been masked.'' During monitoring for the 2022 IHA covering
similar military readiness activities in the ICEX26 Study Area, the
Navy also did not visually observe any marine mammals (U.S. Department
of the Navy, 2022). With the exception of PAM conducted during
activities for mitigation purposes (no detections), PAM did not occur
in 2022 because the ice camp ice flow broke up, and therefore, Navy had
to relocate camp. Given the lost time, multiple research projects were
canceled, including the under-ice PAM that the Naval Postgraduate
School was planning to conduct. During monitoring for the 2024 IHA
covering similar military readiness activities in the ICEX26 Study
Area, the Navy also did not visually observe any marine mammals (U.S.
Department of the Navy, 2025a).
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. 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.
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 the Navy or are the result of coordination between NMFS and
the Navy following receipt of the application, and the Navy has agreed
that all of the mitigation measures are practicable. NMFS has fully
reviewed the specified activities and the mitigation measures included
in the application 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 proposed IHA requires that appropriate personnel (including
civilian personnel) involved in mitigation and training or testing
activity reporting under the specified activities must complete Arctic
Environmental and Safety Awareness Training. Modules include: Arctic
Species Awareness and Mitigations, Environmental Considerations,
Hazardous Materials Management, and General Safety.
Further, the following general mitigation measures are required to
prevent incidental take of ringed seals on the ice floe associated with
the ice camp (further explanation of certain mitigation measures is
provided in parentheses following the measure):
The ice camp and runway must be established on first-year
and multi-year ice without pressure ridges. (This will minimize
physical impacts to subnivean lairs and impacts to sea ice habitat
suitable for lairs);
Ice camp deployment must begin no later than mid-February
2026, and be gradual, with activity increasing over the first 5 days.
Camp deployment must be completed by March 15, 2026. (Given that
mitigation measures require that the
[[Page 51063]]
ice camp and runway be established on first-year or multi-year ice
without pressure ridges, as well as the average ringed seal lair
density in the area, and the relative footprint of the Navy's planned
ice camp (2 km\2\), it is extremely unlikely that a ringed seal would
build a lair in the vicinity of the ice camp. Additionally, based on
the best available science, Arctic ringed seal whelping is not expected
to occur prior to mid-March, and therefore, construction of the ice
camp will be completed prior to whelping in the area of ICEX26.
Further, as noted above, ringed seal lairs are not expected to occur in
the ice camp study area, and therefore, NMFS does not expect ringed
seals to relocate pups due to human disturbance from ice camp
activities, including construction);
Personnel on all on-ice vehicles must observe for marine
and terrestrial animals;
Snowmobiles must follow established routes, when
available. On-ice vehicles must not be used to follow any animal, with
the exception of actively deterring polar bears if the situation
requires;
Personnel on foot and operating on-ice vehicles must avoid
areas of deep (>0.5 m) snowdrifts and pressure ridges by 0.8 km. (These
areas are preferred areas for subnivean lair development);
Personnel must maintain a 100 m avoidance distance from
all observed marine mammals; and
All material (e.g., tents, unused food, excess fuel) and
wastes (e.g., solid waste, hazardous waste) must be removed from the
ice floe upon completion of ICEX26 activities.
The following mitigation measures are required for activities
involving acoustic transmissions (further explanation of certain
mitigation measures is provided in parentheses following the measure):
Personnel must begin passive acoustic monitoring (PAM) for
vocalizing marine mammals 15 minutes prior to the start of activities
involving active acoustic transmissions from submarines and exercise
torpedoes. (This PAM would be conducted for the area around the
submarine in real time by technicians on board the submarine);
Personnel must delay active acoustic transmissions and
exercise torpedo launches if a marine mammal is detected during pre-
activity PAM and must shutdown active acoustic transmissions if a
marine mammal is detected during acoustic transmissions; and
Personnel must not restart acoustic transmissions or
exercise torpedo launches until 15 minutes have passed with no marine
mammal detections.
Ramp up procedures for acoustic transmissions are not required as
the Navy determined, and NMFS concurs, that they would result in
impacts on military readiness and on the realism of training that would
be impracticable.
The following mitigation measures are required for aircraft
activities to prevent incidental take of marine mammals due to the
presence of aircraft and associated noise.
Fixed wing aircraft must operate at the highest altitudes
practicable taking into account safety of personnel, meteorological
conditions, and need to support safe operations of a drifting ice camp.
Aircraft must not reduce altitude if a seal is observed on the ice. In
general, cruising elevation must be 457 m or higher;
UAS must maintain a minimum altitude of at least 15.2 m
above the ice. They must not be used to track or follow marine mammals;
Helicopter flights must use prescribed transit corridors
when traveling to or from Prudhoe Bay and the ice camp. Helicopters
must not hover or circle above marine mammals or within 457 m of marine
mammals;
Aircraft must maintain a minimum separation distance of
1.6 km from groups of 5 or more seals; and
Aircraft must not land on ice within 800 m of hauled-out
seals.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS above, NMFS 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, and areas of similar significance.
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:
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 Navy has coordinated with NMFS to develop an overarching
program, the Integrated Comprehensive Monitoring Program (ICMP),
intended to coordinate marine species monitoring efforts across all
regions and to allocate the most appropriate level and type of effort
for each range complex based on a set of standardized objectives, and
in acknowledgement of regional expertise and resource availability. The
ICMP was created in direct response to Navy requirements established in
various MMPA regulations and ESA consultations. As a framework
document, the ICMP applies by regulation to those activities on ranges
and operating areas for which the Navy is seeking or has sought
incidental take authorizations. In 2023, Navy, NMFS, the Marine Mammal
Commission, and scientific experts participated in a Research and
Monitoring Summit. One outcome of the summit was a refreshed strategic
framework effectively replacing the ICMP, which will provide increased
coordination across Navy's protected marine species investment
programs.
The strategic framework is focused on Navy training and testing
ranges where the majority of Navy activities occur
[[Page 51064]]
regularly, as those areas have the greatest potential for being
impacted by the Navy's activities. In comparison, ICEX is a short
duration exercise that occurs approximately every other year. Due to
the location and expeditionary nature of the ice camp, the number of
personnel on site is extremely limited and is constrained by the
requirement to be able to evacuate all personnel in a single day with
small planes. As such, the Navy asserts that a dedicated monitoring
project akin to those conducted in other study areas is not feasible as
it would require additional personnel and equipment, and NMFS concurs.
Nonetheless, the Navy must conduct the following monitoring and
reporting under the IHA. Ice camp personnel must generally monitor for
marine mammals in the vicinity of the ice camp and record all
observations of marine mammals, regardless of distance from the ice
camp, as well as the additional data indicated below. Additionally,
Navy personnel must conduct PAM during all active sonar use. Ice camp
personnel must also maintain an awareness of the surrounding
environment and document any observed marine mammals. When traveling
away from camp, each snow machine must have a dedicated observer (not
the vehicle operator) or each expeditionary team must have at least one
observer. Observers must be capable of observing and recording marine
mammal presence and behaviors, and accurately and completely record
data. When traveling, observers will have no other primary duty than to
watch for and report observations related to marine mammals and human/
seal interactions. Dedicated observers can also serve as the
communicator between the field party and camp.
In addition, the Navy is required to provide NMFS with a draft
exercise monitoring report within 90 days of the conclusion of the
specified activity. 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 report, at minimum, must include:
Marine mammal monitoring effort including date, time,
duration of observation efforts;
The minimum distance between human activities and seals or
seal lairs;
Duration of time during which seals or seal lairs were
known to be present within 150 m of human activities, and the behaviors
exhibited by the seals during those observation periods;
Account of the status of seal lairs located within 150 m
of camps or ice trails through time;
Ice camp activities occurring during each monitoring
period (e.g., construction, demobilization, safety watch, field
parties);
Number of marine mammals detected;
Upon observation of a marine mammal, record the following
information:
[cir] Environmental conditions when animal was observed, including
relevant weather conditions such as cloud cover, snow, sun glare, and
overall visibility, and estimated observable distance;
[cir] Lookout location and ice camp activity at time of sighting
(or location and activity of personnel who made observation, if
observed outside of designated monitoring periods);
[cir] Time and approximate location of sighting;
[cir] Identification of the animal(s) (e.g., seal, or
unidentified), also noting any identifying features;
[cir] Distance and location of each observed marine mammal relative
to the ice camp location for each sighting;
[cir] Estimated number of animals (min/max/best estimate); and
[cir] Description of any marine mammal behavioral observations
(e.g., observed behaviors such as 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).
Also, all sonar usage will be collected via the Navy's Sonar
Positional Reporting System database. The Navy is required to provide
data regarding sonar use and the number of shutdowns during ICEX26
activities in the Atlantic Fleet Training and Testing (AFTT) Letter of
Authorization 2026 annual classified report. The Navy is also required
to analyze any declassified underwater recordings collected during
ICEX26 for marine mammal vocalizations and report that information to
NMFS, including the types and nature of sounds heard (e.g., clicks,
whistles, creaks, burst pulses, continuous, sporadic, strength of
signal) and the species or taxonomic group (if determinable). This
information will be submitted to NMFS in an ICEX26 declassified
monitoring report.
Finally, in the event that personnel discover an injured or dead
marine mammal, personnel must report the incident to OPR, NMFS and to
the Alaska regional stranding network as soon as feasible. 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(s) was
discovered (e.g., during submarine activities, observed on ice floe, or
by transiting aircraft).
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).
Underwater acoustic transmissions associated with ICEX26, as
outlined previously, have the potential to result in Level B harassment
of ringed seals in the form of TTS and behavioral disturbance. No take
by Level A
[[Page 51065]]
harassment, serious injury, or mortality are anticipated to result from
this activity. Further, at close ranges and high sound levels
approaching those that could cause AUD INJ, seals would likely avoid
the area immediately around the sound source.
NMFS anticipates that take of ringed seals by TTS could occur from
the submarine activities. TTS is a temporary impairment of hearing and
can last from minutes or hours to days (in cases of strong TTS). In
many cases, however, hearing sensitivity recovers rapidly after
exposure to the sound ends. This activity has the potential to result
in only minor levels of TTS, and hearing sensitivity of affected
animals would be expected to recover quickly. Though TTS may occur as
indicated, the overall fitness of the impacted individuals is unlikely
to be affected given the temporary nature of TTS and the minor levels
of TTS expected from these activities. Negative impacts on the
reproduction or survival of affected ring seals as well as impacts on
the stock are not anticipated.
Effects on individuals that are taken by Level B harassment by
behavioral disturbance could include alteration of dive behavior,
alteration of foraging behavior, effects to breathing, 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 and mitigation using PAM,
which would limit exposure to active acoustic sources. Most likely,
individuals would be temporarily displaced by moving away from the
sound source. As described previously in the Acoustic Impacts section,
seals exposed to non-impulsive sources with a received sound pressure
level within the range of calculated exposures (142-193 dB re 1
[mu]Pa), have been shown to change their behavior by modifying diving
activity and avoidance of the sound source (G[ouml]tz et al., 2010;
Kvadsheim et al., 2010). Although a minor change to a behavior may
occur as a result of exposure to the sound sources associated with the
proposed specified activity, these changes would be within the normal
range of behaviors for the animal (e.g., the use of a breathing hole
further from the source, rather than one closer to the source).
Further, given the limited number of total instances of takes and the
unlikelihood that any single individuals would be taken repeatedly,
multiple times over sequential days, these takes are unlikely to impact
the reproduction or survival of any individuals.
The Navy's proposed activities are localized and of relatively
short duration. While the total ICEX Study Area is large, the Navy
expects that most activities would occur within the Ice Camp Study Area
in relatively close proximity to the ice camp. The larger Navy Activity
Study Area depicts the range where submarines may maneuver during the
exercise. The ice camp would be in existence for up to 6 weeks with
acoustic transmission occurring intermittently over approximately 4
weeks.
The project is not expected to have significant adverse effects on
marine mammal habitat. The project activities are limited in time and
would not modify physical marine mammal habitat. While the activities
may cause some fish to leave a specific area ensonified by acoustic
transmissions, temporarily impacting marine mammals' foraging
opportunities, these fish would likely return to the affected area. As
such, the impacts to marine mammal habitat are not expected to cause
significant or long-term negative consequences.
For on-ice activity, Level A harassment, Level B harassment,
serious injury, and mortality are not anticipated, given the nature of
the activities, the lack of previous ringed seal observations, and the
mitigation measures NMFS has proposed to include in the IHA. The ringed
seal pupping season on the ice lasts for 5-9 weeks during late winter
and spring. As stated in the Potential Effects of Specified Activities
on Marine Mammals and their Habitat section, March 1 is generally
expected to be the onset of ice seal lairing season. The ice camp and
runway would be established on first-year ice or multi-year ice without
pressure ridges, as ringed seals tend to build their lairs near
pressure ridges. Ice camp deployment will begin no later than mid-
February, and be gradual, with activity increasing over the first 5
days. Ice camp deployment will be completed by March 15, before the
pupping season. Displacement of seal lair construction or relocation to
existing lairs outside of the ice camp area is unlikely, given the low
average density of lairs (the average ringed seal lair density in the
vicinity of Prudhoe Bay, Alaska, is 1.58 lairs per km\2\ (table 4) the
relative footprint of the Navy's planned ice camp (2 km\2\), the lack
of previous ringed seal observations on the ice during ICEX activities,
and mitigation requirements that require the Navy to construct the ice
camp and runway on first-year or multi-year ice without pressure ridges
and require personnel to avoid areas of deep snow drift or pressure
ridges.
Given that mitigation measures require that the ice camp and runway
be established on first-year or multi-year ice without pressure ridges,
where ringed seals tend to build their lairs, it is extremely unlikely
that a ringed seal would build a lair in the vicinity of the ice camp.
This measure, together with the other mitigation measures required for
operation of the ice camp, are expected to avoid impacts to the
construction and use of ringed seal subnivean lairs, particularly given
the already low average density of lairs, as described above. Given
that ringed seal lairs are not expected to occur in the ice camp study
area, NMFS would not expect ringed seals to relocate pups due to human
disturbance from ice camp activities.
Additional mitigation measures would also prevent damage to and
disturbance of ringed seals and their lairs that could otherwise result
from on-ice activities. Personnel on on-ice vehicles would observe for
marine mammals, and would follow established routes when available, to
avoid potential damage to or disturbance of lairs. Personnel on foot
and operating on-ice vehicles would avoid deep snow drifts near
pressure ridges, also to avoid potential damage to or disturbance of
lairs. Further, personnel would maintain a 100 m (328 ft) distance from
all observed marine mammals to avoid disturbing the animals due to the
personnel's presence. Implementation of these measures would prevent
ringed seal lairs from being crushed or damaged during ICEX26
activities.
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;
Impacts would be limited to Level B harassment, primarily
in the form of behavioral disturbance that results in minor changes in
behavior;
TTS is expected to affect only a limited number of animals
and is expected to be minor and short term;
The number of takes proposed to be authorized are low
relative to the estimated abundances of the affected stock, even given
the extent to which abundance is significantly underestimated;
Submarine training and testing activities would occur over
only 4
[[Page 51066]]
weeks of the total 6-week activity period;
There would be no loss or modification of ringed seal
habitat and minimal, temporary impacts on prey;
Physical impacts to ringed seal subnivean lairs would be
avoided; and
Mitigation requirements for ice camp activities would
prevent impacts to ringed seals during the pupping season.
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.
Impacts to marine mammals from the specified activity would mostly
include limited, temporary behavioral disturbances of ringed seals;
however, some TTS is also anticipated. No Level A harassment (auditory
or non-auditory injury), serious injury, or mortality of marine mammals
is expected or proposed for authorization, and the activities are not
expected to have any impacts on reproductive or survival rates of any
marine mammal species.
The specified activity and associated harassment of ringed seals
would not be expected to impact marine mammals in numbers or locations
sufficient to reduce their availability for subsistence harvest given
the short-term, temporary nature of the activities, and the distance
offshore from known subsistence hunting areas. The specified activity
would occur for a brief period of time outside of the primary
subsistence hunting season, and though seals are harvested for
subsistence uses off the North Slope of Alaska, the ICEX Study Area is
seaward of known subsistence hunting areas. The Study Area boundary is
approximately 50 km from shore at the closest point, though exercises
will occur farther offshore.
The Navy proposes to provide advance public notice to local
residents and other users of the Prudhoe Bay region of Navy activities
and measures used to reduce impacts on resources. This includes
notification to local Alaska Natives who hunt marine mammals for
subsistence. If any Alaska Natives express concerns regarding project
impacts to subsistence hunting of marine mammals, the Navy would
further communicate with the concerned individuals or community. The
Navy would provide project information and clarification of the
mitigation measures that will reduce impacts to marine mammals.
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 the
Navy'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 designated critical
habitat. To ensure ESA compliance for the issuance of IHAs, NMFS
consults internally whenever we propose to authorize take for
endangered or threatened species, in this case with NMFS' Alaska
Regional Office (AKR).
NMFS Office of Protected Resources (OPR) is proposing to authorize
take of ringed seals, which are listed under the ESA. OPR has requested
initiation of section 7 consultation with AKR for the issuance of this
IHA. The Navy has also requested a section 7 consultation with AKR for
ICEX26 activities. OPR will conclude the ESA consultation prior to
reaching a determination regarding the proposed issuance of the
authorization.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to the Navy for conducting submarine training and testing
activities in the Arctic Ocean beginning in February 2026, 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 ICEX26
activities. 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
[[Page 51067]]
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: November 10, 2025.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2025-19886 Filed 11-13-25; 8:45 am]
BILLING CODE 3510-22-P