[Federal Register Volume 89, Number 25 (Tuesday, February 6, 2024)]
[Notices]
[Pages 8172-8183]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-02383]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD588]


Takes of Marine Mammals Incidental To Specified Activities; 
Taking Marine Mammals Incidental to U.S. Navy 2024 Ice Exercise 
Activities in the Arctic Ocean

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

ACTION: Notice; issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
the U.S. Navy (Navy) to incidentally harass marine mammals during 
submarine training and testing activities associated with a 2024 Ice 
Exercise (ICEX24) Activities in the Arctic Ocean.

DATES: This authorization is effective from February 1, 2024 through 
April 30, 2024.

ADDRESSES: Electronic copies of the application and supporting 
documents, as well as a list of the references cited in this document, 
may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems accessing these documents, 
please call the contact listed below.

[[Page 8173]]


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

SUPPLEMENTARY INFORMATION: 

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed 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 (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.
    The 2004 National Defense Authorization Act (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.

Summary of Request

    On May 24, 2023, NMFS received a request from the Navy for an IHA 
to take marine mammals incidental to submarine training and testing 
activities including establishment of a tracking range on an ice floe 
in the Arctic Ocean, north of Prudhoe Bay, Alaska. Following NMFS' 
review of the application, the Navy submitted a revised application on 
October 13, 2023 that removed the request for take of bearded seal and 
included an updated take estimate for ringed seals. The application was 
deemed adequate and complete on October 19, 2023. The Navy's request is 
for take of ringed seal by Level B harassment. 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). 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 
Estimated Take of Marine Mammals section.

Description of the Specified Activity

    The Navy proposes to conduct submarine training and testing 
activities, which includes the establishment of a tracking range and 
temporary ice camp, and research in the Arctic Ocean for six weeks 
beginning in February 2024. Submarine active acoustic transmissions may 
result in occurrence of Level B harassment, including direct behavioral 
disturbance or temporary hearing impairment (temporary threshold shift 
(TTS)), of ringed seals. A detailed description of the planned ICEX24 
activities is provided in the Federal Register notice for the proposed 
IHA (88 FR 85244, December 7, 2023). Since that time, no changes have 
been made to the planned activities. Therefore, a detailed description 
is not provided here. Please refer to that Federal Register notice for 
the description of the specific activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to the Navy was 
published in the Federal Register on December 7, 2023 (88 FR 85244). 
That notice described, in detail, the Navy's activity, the marine 
mammal species that may be affected by the activity, and the 
anticipated effects on marine mammals. In that notice, we requested 
public input on the request for authorization described therein, our 
analyses, the proposed authorization, and any other aspect of the 
notice of proposed IHA, and requested that interested persons submit 
relevant information, suggestions, and comments. During the 30-day 
public comment period, NMFS did not receive any public comments.

Changes From the Proposed IHA to Final IHA

    Since publication of the proposed IHA, NMFS made two updates to the 
required mitigation measures. The proposed IHA required that 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 305 meters (m; 1,000 feet (ft)) or higher. This final 
IHA requires that cruising elevation must be 457 m (1,500 ft) or 
higher. This change aligns with NMFS' biological opinion and the U.S. 
Fish and Wildlife Service's requirements for polar bears. Further, NMFS 
updated its requirement for personnel on foot and operating on-ice 
vehicles to avoid areas of deep snowdrifts and pressure ridges to 
clarify that a deep snow drift is one that is >0.5 m, and these areas 
must be avoided by 0.8 kilometers (km), consistent with NMFS' 
biological opinion.
    NMFS also added a requirement that 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. These changes and additions align 
with NMFS' biological opinion.
    Last, NMFS added several reporting measures to this final IHA to 
align with NMFS' biological opinion. The Navy must report the 
following: the minimum distance between human activities and seals or 
seal lairs; the 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; and an account 
of the status of all seal lairs located within 150 m of camps or ice 
trails through time.

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

[[Page 8174]]

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 1 lists all species or stocks for which take is expected and 
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 authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species or 
stocks and other threats. That said, in this case for the Arctic stock 
of ringed seals and as explained in footnote 5 of table 1, the lack of 
complete population information significantly impacts the usefulness of 
PBR in considering the status of the stock, as explained below.
    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. 2023). 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. However, for 
the same reason noted above and as described in footnote 5 of table 1, 
the lack of complete population information for the Arctic stock of 
ringed seals impacts the usefulness of these numbers in considering the 
impacts of the anticipated take on the stock.

                                            Table 1--Species Likely Impacted by the Specified Activities \1\
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                                                                                     ESA/ MMPA status;   Stock abundance (CV,
            Common name                  Scientific name              Stock           strategic (Y/N)      Nmin, most recent        PBR      Annual M/SI
                                                                                            \2\          abundance survey) \3\                   \4\
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Ringed Seal........................  Pusa hispida..........  Arctic................  T, D, Y            UND \5\ (UND, UND,              UND    \6\ 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\ 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 SARs online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region.
  CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\5\ 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\ The majority of the M/SI for this stock (6,454 of 6,459 animals) is a result of the Alaska Native subsistence harvest. While M/SI appears to exceed
  PBR, given that the reported PBR is based on a partial stock abundance estimate, and is therefore an underestimate for the full stock, M/SI likely
  does not exceed PBR.

    As indicated in table 1, 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), and spotted seals (Phoca largha) may occur in the ICEX24 
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 ICEX24 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 during April and May (Young et al. 2023). 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 (124.3 miles (mi)). The distance 
between Point Barrow and the closest edge of the Navy Activity Study 
Area is over 50 km (31 mi), and the distance between Point Barrow and 
Point Hope is an additional 525 km (326.2 mi; straight line distance); 
accordingly, bowhead whales are unlikely to occur in the ICEX24 Study 
Area before ICEX24 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 ICEX24 Study Area, they are unlikely to occur in the ICEX24 Study 
Area between February and April. (Of note, the ICEX24 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), 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 ICEX24 Study Area during the Navy's activities.) 
Gray whales feed primarily in the Beaufort Sea, Chukchi Sea, and

[[Page 8175]]

Northwestern Bering Sea during the summer and fall, but migrate south 
to winter in Baja California lagoons (Young et al. 2023). Typically, 
northward migrating gray whales do not reach the Bering Sea before May 
or June (Frost and Karpovich 2008), after the ICEX24 activities would 
occur, and several hundred kilometers south of the ICEX24 Study Area. 
Further, gray whales are primarily bottom feeders (Swartz et al. 2006) 
in water less than 60 m (196.9 ft) 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 ICEX24 Study 
Area during the ICEX24 activity period. Spotted seals may also occur in 
the ICEX24 Study Area during summer and fall, but they are not expected 
to occur in the ICEX24 Study Area during the ICEX24 timeframe (Muto et 
al. 2020).
    Further, while the Navy initially requested take of bearded seals 
(Erignathus barbatus), which do occur in the ICEX24 Study Area during 
the project timeframe, NMFS does not expect that bearded seals would 
occur in the areas near the ice camp or where submarine activities 
involving active acoustics would occur, and therefore incidental take 
is not anticipated to occur and has not been proposed for 
authorization. Bearded seals are not discussed further beyond the 
explanation provided here. The Navy anticipates that the ice camp would 
be established 100-200 nautical miles (nmi; 185-370 km) north of 
Prudhoe Bay in water depths of 800 m (2,625 ft) or more, and also that 
submarine training and testing activities would occur in water depths 
of 800 m (2,625 ft) or more. Although acoustic data indicate that some 
bearded seals remain in the Beaufort Sea year round (MacIntyre et al. 
2013, 2015; Jones et al. 2014), satellite tagging data (Boveng and 
Cameron 2013; ADF&G 2017) 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; Frost et al. 2008; Cameron and Boveng 2009). 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 ICEX24 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 ICEX24 activities will 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; Quakenbush et al. 2011; Cameron et al. 2010) and are typically 
found in water depths of 200 m (656 ft) or less (Burns 1970). The 
Bureau of Ocean Energy Management (BOEM) conducted an aerial survey 
from June through October that covered the shallow Beaufort and Chukchi 
Sea shelf waters and observed bearded seals from Point Barrow to the 
border of Canada (Clarke et al. 2015). The farthest from shore that 
bearded seals were observed was the waters of the continental slope 
(though this study was conducted outside of the ICEX24 time frame). The 
Navy anticipates that the ice camp will be established 185-370 km (100-
200 nmi) north of Prudhoe Bay in water depths of 800 m (2,625 ft) or 
more. The continental shelf near Prudhoe Bay is approximately 55 nmi 
(100 km) wide. Therefore, even if the ice camp were established at the 
closest estimated distance (100 nmi from Prudhoe Bay), it would still 
be approximately 45 nmi (83 km) distant from habitat potentially 
occupied by bearded seals. Empirical evidence has not shown responses 
to sonar that would constitute take beyond a few km from an acoustic 
source, and therefore, NMFS and the Navy conservatively set a distance 
cutoff of 10 km (6.2 mi). Regardless of the source level at that 
distance, take is not estimated to occur beyond 10 km (6.2 mi) from the 
source. Although bearded seals occur 20 to 100 nmi (37 to 185 km) 
offshore during spring (Simpkins et al. 2003, Bengtson et al. 2005), 
they feed heavily on benthic organisms (Hamilton et al. 2018; Hjelset 
et al. 1999; Fedoseev 1965), 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 (2,625 
ft) to forage (Boveng and Cameron, 2013; Cameron and Boveng 2009; 
Cameron et al. 2010; Gjertz et al. 2000; Kovacs 2002), and it is highly 
unlikely that 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 or 2022 ice exercises.
    In addition, the polar bear (Ursus maritimus) may be found in the 
ICEX24 Study Area. However, polar bears are managed by the U.S. Fish 
and Wildlife Service and are not considered further in this document.
    A detailed description of the of the Arctic stock of ringed seals, 
including brief introductions to the species and stock as well as 
available information regarding population trends and threats, and 
information regarding local occurrence, were provided in the Federal 
Register notice for the proposed IHA (88 FR 85244, December 7, 2023); 
since that time, we are not aware of any changes in the status of these 
species and stocks; therefore, detailed descriptions are not provided 
here. Please refer to that Federal Register notice for these 
descriptions. Please also refer to NMFS' website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al. 1995; Wartzok and Ketten, 
1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007, 
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.). Note that no direct measurements of hearing 
ability have been successfully completed for mysticetes (i.e., low-
frequency cetaceans). Subsequently, NMFS (2018) described generalized 
hearing ranges for these marine mammal hearing groups. Generalized 
hearing ranges were chosen based on the approximately 65 decibels (dB) 
threshold from the normalized composite audiograms, with the exception 
for lower limits for low-frequency cetaceans where the lower bound was 
deemed to be biologically implausible and the lower bound from Southall 
et al. (2007) retained. Marine mammal hearing groups and their 
associated hearing ranges are provided in table 2.

[[Page 8176]]



                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
                                              Generalized  hearing range
               Hearing group                              *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen         7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans (dolphins,      150 Hz to 160 kHz.
 toothed whales, beaked whales, bottlenose
 whales).
High-frequency (HF) cetaceans (true          275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus cruciger &
 L. australis).
Phocid pinnipeds (PW) (underwater) (true     50 Hz to 86 kHz.
 seals).
Otariid pinnipeds (OW) (underwater) (sea     60 Hz to 39 kHz.
 lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al. 2006; Kastelein et al. 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The underwater noise from the Navy's submarine training and testing 
activities has the potential to result in behavioral harassment of 
marine mammals in the vicinity of the ICEX24 Study Area. The notice of 
proposed IHA (88 FR 85244, December 7, 2023) included a discussion of 
the effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from Navy's activities on marine mammals 
and their habitat. That information and analysis is referenced in this 
final IHA determination and is not repeated here; please refer to the 
notice of proposed IHA (88 FR 85244, December 7, 2023).

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
authorized through this 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 for individual marine mammals resulting from 
exposure to acoustic transmissions are by Level B harassment only, in 
the form of direct behavioral disturbance including TTS, which can be 
associated with disruptions in behavioral patterns resulting from an 
animal missing some acoustic cues during the time that their hearing 
sensitivity is reduced. Based on the nature of the activity, Level A 
harassment is neither anticipated nor authorized. As described 
previously, no serious injury or mortality is anticipated nor 
authorized for this activity. Below we describe how the take numbers 
are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (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 take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds 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 permanent threshold shift (PTS) of some 
degree (equated to Level A harassment).
    Level B Harassment--In coordination with NMFS, the Navy developed 
behavioral thresholds to support environmental analyses for the Navy's 
testing and training military readiness 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 specified 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 (e.g., Southall et al. 2007, 2021; Ellison et al. 
2012).
    The Navy's Phase III proposed pinniped behavioral threshold was 
updated based on controlled exposure experiments on the following 
captive animals: Hooded seal, gray seal, and California sea lion 
(G[ouml]tz et al. 2010; Houser et al. 2013a; Kvadsheim et al. 2010). 
Overall exposure levels were 110-170 dB referenced to 1 micropascal (re 
1 [mu]Pa) for hooded seals, 140-180 dB re 1 [mu]Pa for gray seals, and 
125-185 dB re 1 [mu]Pa for California sea lions; responses occurred at 
received levels ranging from 125-185 dB re 1 [mu]Pa. However, the means 
of the response data were between 159 and 170 dB re 1 [mu]Pa. Hooded 
seals were exposed to increasing levels of sonar until an avoidance 
response was observed, while the grey seals were exposed first to a 
single received level multiple times, then an increasing received 
level. Each

[[Page 8177]]

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. Because these data represent a dose-response type 
relationship between received level and a response, and because the 
means were all tightly clustered, the Bayesian biphasic Behavioral 
Response Function for pinnipeds most closely resembles a traditional 
sigmoidal dose-response function at the upper received levels and has a 
50 percent probability of response at 166 dB re 1 [mu]Pa. Additionally, 
to account for proximity to the source discussed above and based on the 
best scientific information, a conservative distance of 10 km is used 
beyond which exposures would not constitute a take under the military 
readiness definition of Level B harassment.
    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). The Navy's 
activities include the use of non-impulsive (active sonar) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
    For previous ICEXs, 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.
    Table 3 below provides the weighted criteria and thresholds used in 
previous ICEX analyses for estimating quantitative acoustic exposures 
of marine mammals from the specified activities.

  Table 3--Acoustic Thresholds Identifying the Onset of Behavioral Disturbance, TTS, and PTS for Non-Impulsive
                                                Sound Sources \1\
----------------------------------------------------------------------------------------------------------------
                                                                                   Physiological criteria
                                                            Behavioral     -------------------------------------
    Functional hearing group            Species              criteria       TTS threshold SEL  PTS threshold SEL
                                                                                (weighted)         (weighted)
----------------------------------------------------------------------------------------------------------------
Phocid Pinnipeds (Underwater)..  Ringed seal..........  Pinniped Dose       181 dB SEL         201 dB SEL
                                                         Response Function   cumulative.        cumulative.
                                                         \2\.
----------------------------------------------------------------------------------------------------------------
\1\ The threshold values provided are assumed for when the source is within the animal's best hearing
  sensitivity. The exact threshold varies based on the overlap of the source and the frequency weighting.
\2\ See Figure 6-1 in the Navy's IHA application.
Note: SEL thresholds in dB re: 1 [mu]Pa\2\s.

Marine Mammal Occurrence and Take Calculation and Estimation

    In previous ICEX analyses, the Navy has performed a quantitative 
analysis to estimate the number of ringed seals that could be harassed 
by the underwater acoustic transmissions during the proposed specified 
activities using marine mammal density estimates (Kaschner et al. 2006; 
Kaschner 2004), marine mammal depth occurrence distributions (U.S 
Department of the Navy, 2017), oceanographic and environmental data, 
marine mammal hearing data, and criteria and thresholds for levels of 
potential effects. Given the lack of recent density estimates for the 
ICEX Study Area and the lack of ringed seal observations and acoustic 
detections during ICEXs in the recent past (described in further detail 
below), NMFS expects that the ringed seal density relied upon in 
previous ICEX analyses was an overestimate to a large degree, and that 
the resulting take estimates were likely overestimates as well. Please 
see the notice of the final IHA for ICEX 22 for additional information 
on that analysis (87 FR 7803, January 10, 2022).
    For ICEX24, rather than relying on a density estimate, the Navy 
estimated take of ringed seals based on an occurrence estimate of 
ringed seals within the ICEX Study Area. 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 for years 2000 to 2007 and 2013. Sighting data 
were only available for the mid-to-late summer and fall months. Due to 
the paucity of winter and spring data, the average number of individual 
ringed seals per year was assumed to be present in the ICEX Study Area 
during ICEX24; therefore, it is assumed that three ringed seals would 
be present in the ICEX Study Area.
    Table 4 provides range to effects for active acoustic sources 
proposed for ICEX24 to phocid pinniped-specific criteria. Phocids 
within these ranges would be predicted to receive the associated 
effect. Range to effects can be important information for predicting 
acoustic impacts, but also in determining adequate mitigation ranges to 
avoid higher level effects, especially physiological effects, to marine 
mammals.

[[Page 8178]]



                 Table 4--Range to Behavioral Disturbance, TTS, and PTS in the ICEX24 Study Area
----------------------------------------------------------------------------------------------------------------
                                                                             Range to effects  (m)
                                                              --------------------------------------------------
                       Source/exercise                            Behavioral
                                                                 disturbance          TTS              PTS
----------------------------------------------------------------------------------------------------------------
Submarine Exercise...........................................      10,000 \a\            5,050          130 \b\
----------------------------------------------------------------------------------------------------------------
\a\ Empirical evidence has not shown responses to sonar that would constitute take beyond a few km from an
  acoustic source, which is why NMFS and the Navy conservatively set a distance cutoff of 10 km. Regardless of
  the source level at that distance, take is not estimated to occur beyond 10 km from the source.
\b\ The distance represents the range to effects for all ICEX24 activities.

    Though likely conservative given the size of the ICEX Study Area in 
comparison to the size of the anticipated Level B harassment zone 
(10,000 m), 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 5). 
NMFS concurs and proposes to authorize 126 takes by Level B harassment. 
Modeling for the 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) and the relatively 
small range to effects for PTS (130 m), the Navy did not request, and 
NMFS has not authorized, take by Level A harassment of ringed seal.

                Table 5--Quantitative Modeling Results of Potential Exposures for ICEX Activities
----------------------------------------------------------------------------------------------------------------
                                                                   Level B          Level A
                           Species                                harassment       harassment         Total
----------------------------------------------------------------------------------------------------------------
Ringed seal..................................................             126                0              126
----------------------------------------------------------------------------------------------------------------

    During monitoring for the 2018 IHA covering similar military 
readiness activities in the ICEX22 Study Area, the Navy did not 
visually observe or acoustically detect any marine mammals (U.S. Navy, 
2018). During monitoring for the 2020 IHA covering similar military 
readiness activities in the ICEX22 Study Area, the Navy also did not 
visually observe any marine mammals (U.S. 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 centimeters (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 ICEX24 Study Area, the Navy also did not 
visually observe any marine mammals (U.S. Navy, 2022). With the 
exception of passive acoustic monitoring (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.

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, as 
well as subsistence uses. This considers the nature of the potential 
adverse impact being mitigated (likelihood, scope, range). It further 
considers the

[[Page 8179]]

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 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 
2024, and be gradual, with activity increasing over the first 5 days. 
Camp deployment must be completed by March 15, 2024. (Given that 
mitigation measures require that the 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\ 0.8 mi\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 ICEX24. 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 in accordance with U.S. 
Fish and Wildlife Service requirements or guidance 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 (328 ft) 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 ICEX24 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 PAM for vocalizing marine mammals 15 
minutes prior to the start of activities involving active acoustic 
transmissions from submarines. (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 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 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 (1,500 ft) or higher;
     Unmanned Aircraft Systems (UAS) must maintain a minimum 
altitude of at least 15.2 m (50 ft) 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 (1,500 
ft) of marine mammals;
     Aircraft must maintain a minimum separation distance of 
1.6 km (1 mi) from groups of 5 or more seals; and
     Aircraft must not land on ice within 800 m (0.5 mi) of 
hauled-out seals.
    Based on our evaluation of the required measures, as well as other 
measures considered by NMFS as described above, NMFS has determined 
that the 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.

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

[[Page 8180]]

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.
    The ICMP is focused on Navy training and testing ranges where the 
majority of Navy activities occur regularly, as those areas have the 
greatest potential for being impacted 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 ICMP monitoring project is not feasible as it would require 
additional personnel and equipment, and NMFS concurs. However, the Navy 
is exploring the potential of implementing an environmental DNA (eDNA) 
study on ice seals.
    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 ICEX24 
activities in the Atlantic Fleet Training and Testing (AFTT) Letter of 
Authorization 2025 annual classified report. The Navy is also required 
to analyze any declassified underwater recordings collected during 
ICEX24 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 also be submitted to NMFS with the 2025 annual AFTT 
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

[[Page 8181]]

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 ICEX24, as 
outlined previously, have the potential to result in Level B harassment 
of ringed seals in the form of behavioral disturbance and TTS. Given 
the nature of the activity, no take by Level A harassment, serious 
injury, or mortality are anticipated to result from this activity even 
absent mitigation, and no such takes are authorized. Further, at close 
ranges and high sound levels approaching those that could cause PTS, 
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) and 
which can result in disruptions to behavioral patterns from missing 
acoustic cues associated with, for example, conspecific communication 
or prey detection. 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 ringed 
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 activities are localized and of relatively short 
duration. While the total ICEX24 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 required in the IHA. The ringed seal 
pupping season on the ice lasts for 5 to 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\), the relative 
footprint of the Navy's planned ice camp (2 km\2\; 0.77 mi\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 does not expect ringed seals to relocate pups due to human 
disturbance from ice camp activities.

[[Page 8182]]

    Additional mitigation measures are also expected to prevent damage 
to and disturbance of ringed seals and their lairs that could otherwise 
result from on-ice activities. Personnel on on-ice vehicles are 
required to observe for marine mammals, and must follow established 
routes when available, to avoid potential damage to or disturbance of 
lairs. Personnel on foot and operating on-ice vehicles must avoid deep 
(>0.5 m) snow drifts and pressure ridges by 0.8 km, also to avoid 
potential damage to or disturbance of lairs. Further, personnel must 
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 will prevent ringed seal lairs from 
being crushed or damaged during ICEX24 activities.
    In summary and as described above, the following factors primarily 
support our 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 (injury), 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 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 will occur over 
only 4 weeks of the total 6-week activity period;
     There will be no loss or modification of ringed seal 
habitat and minimal, temporary impacts on prey;
     Physical impacts to ringed seal subnivean lairs will be 
avoided; and
     Mitigation requirements for ice camp activities are 
expected to 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 required monitoring and 
mitigation measures, NMFS finds that the total marine mammal take from 
the planned 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 direct behavioral disturbances of ringed 
seals; however, some TTS is also anticipated. No Level A harassment 
(injury), serious injury, or mortality of marine mammals is expected or 
authorized, 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 ICEX24 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 will 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 required mitigation and 
monitoring measures, NMFS has 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 insure 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 
(AKRO).
    The NMFS Office of Protected Resources is authorizing take of 
ringed seals, which are listed under the ESA. The NMFS AKRO Protected 
Resources Division issued a Biological Opinion on January 11, 2024, 
which concluded that the Navy's activities and NMFS' issuance of an IHA 
are not likely to jeopardize the continued existence of the Arctic 
stock of ringed seals, and is not likely to destroy or adversely modify 
their critical habitat.

National Environmental Policy Act

    In compliance with the National Environmental Policy Act of 1969 
(42 U.S.C. 4321 et seq.), as implemented by the regulations published 
by the Council on Environmental Quality (40 CFR parts 1500-1508), the 
Navy prepared a Supplemental Environmental Assessment/Overseas 
Environmental Assessment (SEA/OEA) to consider the direct, indirect and 
cumulative effects to the human environment resulting from ICEX24, 
focusing on changes between ICEX24, and ICEX22 (e.g., no torpedo 
training exercises in ICEX24 and new available science). This SEA/OEA 
supplements an EA/OEA published in 2022 for ICEX22 that was finalized 
in February 2022. NMFS adopted that EA/OEA and signed a Finding of No 
Significant Impact (FONSI) on February 4, 2022.
    The Navy's SEA/OEA was made available for public comment at https://www.nepa.navy.mil/icex/ from September 29, 2023 to October 13, 2023. 
In the notice of proposed IHA (88 FR

[[Page 8183]]

85244, December 7, 2023), NMFS described its plan to adopt the Navy's 
SEA/OEA, provided our independent evaluation of the document found that 
it includes adequate information analyzing the effects on the human 
environment of issuing the IHA. In compliance with NEPA and the CEQ 
regulations, as well as NOAA Administrative Order 216-6A, NMFS has 
reviewed the Navy's SEA/OEA, determined it to be sufficient, and 
adopted that SEA/OEA and signed a FONSI on January 31, 2024.

Authorization

    NMFS has issued an IHA to the Navy for the potential harassment of 
ringed seals incidental to ICEX24 in the Arctic Ocean that includes the 
previously explained mitigation, monitoring and reporting requirements.

    Dated: February 1, 2024.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2024-02383 Filed 2-5-24; 8:45 am]
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