[Federal Register Volume 88, Number 84 (Tuesday, May 2, 2023)]
[Notices]
[Pages 27464-27487]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-09041]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC662]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Port of Nome Modification 
Project in Nome, Alaska

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. Army Corps of 
Engineers (USACE) for authorization to take marine mammals incidental 
to the Port of Nome Modification Project in Nome, Alaska. 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.

DATES: Comments and information must be received no later than June 1, 
2023.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email to 
[email protected].
    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 
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: Leah Davis, Office of Protected 
Resources, NMFS, (301) 427-8401. 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-construction-activities. In case of problems 
accessing these documents, please call the contact listed above.

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.

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

[[Page 27465]]

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 NOAA Administrative Order 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 October 31, 2022, NMFS received a request from USACE for an IHA 
to take marine mammals incidental to construction activities in Nome, 
Alaska. Following NMFS' review of the application, USACE submitted a 
revised version on February 21, 2023 and a final version on February 
23, 2023 that clarified a few minor errors. The application was deemed 
adequate and complete on March 30, 2023. USACE's request is for take of 
10 species of marine mammals by Level B harassment only. Neither USACE 
nor NMFS expect serious injury or mortality to result from this 
activity and, therefore, an IHA is appropriate.
    This proposed IHA would cover 1 year of a larger project for which 
USACE intends to request take authorization for subsequent facets of 
the project. The larger 7-year project involves expansion of the Port 
of Nome.

Description of Proposed Activity

Overview

    USACE is planning to modify the Port of Nome in Nome, Alaska to 
increase capacity and alleviate congestion at existing port facilities. 
Vibratory and impact pile driving would introduce underwater sounds 
that may result in take, by Level B harassment, of marine mammals. This 
proposed IHA would authorize take for Year 1 of Phase 1 of the project, 
which is scheduled to begin in May 2024. Work would occur during 
daylight hours and approximately 12 hours per day during the open water 
season.

Dates and Duration

    The proposed IHA would be effective from May 1, 2024 to April 30, 
2025. Work would occur during the open water season, roughly May 
through October. In-water construction activities would only occur 
during daylight hours, and typically over a 12-hour workday. However, 
when needed and due to the long summer day length at Nome's latitude, 
24-hour, multi-shift operations may occur. For calculations herein, 
USACE conservatively assumed that 24 hours of work could occur in a 
given day (e.g., in estimating the number of piles for installation on 
a given day). Pile driving is expected to occur over 85 in-water work 
days.

Specific Geographic Region

    The Port of Nome Modification Project is located in Norton Sound, 
just offshore of Nome, Alaska. All construction activities would occur 
within approximately 3,600 feet (ft; 1,097 m) of the shoreline. The 
seabed in this area is flat and featureless, with bottom sediments 
consisting of sand and silt, with scattered cobbles and boulders. The 
nearshore waters are shallow and deepen very gradually, reaching a 
depth of 60 ft (18 m) at roughly 2 nautical miles (nmi; 3.7 km) 
offshore. In the Nome area, sea ice formation typically occurs in early 
November each year with spring break-up usually occurring in late May.
[GRAPHIC] [TIFF OMITTED] TN02MY23.002

Figure 1--Project Location

[[Page 27466]]

Detailed Description of the Specified Activity

    The City of Nome and USACE are proposing to expand the Port of Nome 
to provide much-needed additional capacity to serve the Arctic as well 
as to alleviate congestion at the existing port facilities. As noted 
above, this proposed IHA would authorize take associated with Year 1 of 
Phase 1 of the project only. Please refer to USACE's application for 
additional information about project components planned for the period 
beyond Year 1.
    The USACE estimates that Year 1 activities would include 
mobilization, removal of the breakwater spur, development of the quarry 
for rock and gravel (i.e., fill), dredging of the causeway footprint to 
accommodate for armor stone installation, pile driving for the OPEN 
CELL SHEET PILE\TM\ (OCSP) dock, and placement of gravel fill inside 
new sheet pile cells. Additionally, USACE anticipates approximately 20 
round trip vessel trips (i.e., barge, support tugs, fuel, etc.) to 
occur between Nome and Anchorage during Year 1. With the exception of 
pile driving, these activities are not anticipated to result in take. 
Mobilization activities would occur on land, as would development of 
the quarry for rock and gravel (likely to occur at Cape Nome quarry). 
While marine mammals may behaviorally respond in some small degree to 
the noise generated by dredging operations, given the slow, predictable 
movements of these vessels, and absent any other contextual features 
that would cause enhanced concern, NMFS does not expect USACE's planned 
dredging to result in the take of marine mammals. (Though, as noted 
below, USACE has conservatively proposed to implement a 300 m shutdown 
zone for dredging.)
    Gravel fill deposition would produce a continuous sound of a 
relatively short duration, does not require seafloor penetration, and 
would not affect habitat for marine mammals and their prey beyond that 
already affected by installation of the OCSP, discussed below. Further, 
placement of gravel fill would occur in a dry area behind the sheet 
piles, and placement would occur in a controlled manner so as not to 
compromise the newly installed piles. Gravel deposition is not expected 
to result in marine mammal harassment and it is not discussed further.
    Because vessels will be in transit, exposure to ship noise will be 
temporary, relatively brief and will occur in a predictable manner, and 
also the sounds are of relatively lower levels. Elevated background 
noise from multiple vessels and other sources can interfere with the 
detection or interpretation of acoustic cues, but the brief exposures 
to one or two USACE vessels at a time would be unlikely to disrupt 
behavioral patterns in a manner that would qualify as take.
    The OCSP dock would consist of approximately 66 cells when 
complete. Cells are constructed utilizing flat-web sheet piles, 
connector x-wyes (fabricated from three one-half-width sheet pile 
sections), and anchor piles. After all the piles for a cell have been 
installed, clean gravel fill would be placed within the cell. This 
process would continue sequentially until all the sheet pile cells are 
installed and backfilled. The cells are typically constructed one at a 
time. The contractor may use two sets of templates to allow for 
completing the pile driving of one cell and starting on the next while 
removing and reinstalling the template from the completed cell. 
However, only one hammer would be used at a time.
    Table 1 lists the number of each pile size and type that USACE 
anticipates installing and/or removing during Year 1. USACE anticipates 
driving piles with a vibratory hammer; however, it may use an impact 
hammer if hard driving conditions are encountered and use of the 
vibratory hammer is unsuccessful.

  Table 1--Number and Type of Piles Planned for Installation or Removal
------------------------------------------------------------------------
                                                             Number of
             Pile type              Installation/removal       piles
------------------------------------------------------------------------
Temporary template piles..........  Installation and             \a\ 228
(Pipe piles <=24'')...............   Removal.
(Alternate) Temporary template      Installation and                 228
 piles (H-piles 14'') a b.           Removal.
Anchor piles6 (14'' HP14x89 or      Installation........              27
 similar).
Sheet piles.......................  Installation........           1,600
(20'' PS31 or similar)............
Fender piles......................  Installation........              21
(Pipe piles 36'').................
------------------------------------------------------------------------
\a\ Each of the 228 piles would be both installed and removed.
\b\ H-piles may be used as an alternate in place of the pipe piles.

    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; 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 from 
anthropogenic sources are included here as gross indicators of the 
status of the species or stocks and other threats.

[[Page 27467]]

    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 (e.g., Muto et al., 2022). All values presented 
in Table 2 are the most recent available at the time of publication 
(including from the draft 2022 SARs) and are available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments).

                    Table 2--Marine Mammal Species \1\ Likely To Occur Near the Project Area That May Be Taken by USACE's 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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                                                 Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
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Family Eschrichtiidae:
    Gray Whale......................  Eschrichtius robustus..  Eastern N Pacific......  -, -, N             26,960 (0.05, 25,849,         801        131
                                                                                                             2016).
Family Balaenopteridae (rorquals):
    Minke Whale.....................  Balaenoptera             AK.....................  -, -, N             N/A (N/A, N/A, N/A)           UND          0
                                       acutorostrata.                                                        \5\.
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                                                  Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
    Killer Whale....................  Orcinus orca...........  Eastern North Pacific    -, -, N             1,920 \6\ (N/A, 1,920,         19        1.3
                                                                Alaska Resident.                             2019).
    Killer Whale....................  Orcinus orca...........  Eastern North Pacific    -, -, N             587 \6\ (N/A, 587,            5.9        0.8
                                                                Gulf of Alaska,                              2012).
                                                                Aleutian Islands and
                                                                Bering Sea Transient.
Family Monodontidae (white whales):
    Beluga Whale....................  Delphinapterus leucas..  Eastern Bering Sea.....  -,-, N              12,269 (0.118, 11,112,        267        226
                                                                                                             2017).
Family Phocoenidae (porpoises):
    Harbor Porpoise.................  Phocoena phocoena......  Bering Sea.............  -, -, Y             UNK (UNK, N/A, 2008)      UND \7\        0.4
                                                                                                             \7\.
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                                                               Order Carnivora--Pinnipedia
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Family Otariidae (eared seals and
 sea lions):
    Steller Sea Lion................  Eumetopias jubatus.....  Western................  E, D, Y             52,932 \8\ (N/A,              318        254
                                                                                                             52,932, 2019).
Family Phocidae (earless seals):
    Bearded Seal....................  Erignathus barbatus....  Beringia...............  T, D, Y             UND (UND, UND, 2013)      \9\ UND      6,709
                                                                                                             \9\.
    Ribbon Seal.....................  Histriophoca fasciata..  Unidentified...........  -, -, N             184,697 (N/A, 163,086,      9,785        163
                                                                                                             2013).
    Ringed Seal.....................  Pusa hispida...........  Arctic.................  T, D, Y             UND (UND, UND, 2013)     \10\ UND      6,459
                                                                                                             \10\.
    Spotted Seal....................  Phoca largha...........  Bering.................  -, -, N             461,625 (N/A, 423,237,     25,394      5,254
                                                                                                             2013).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\5\ Reliable population estimates are not available for this stock. Please see Friday et al. (2013) and Zerbini et al. (2006) for additional information
  on numbers of minke whales in Alaska.
\6\ Nest is based upon counts of individuals identified from photo-ID catalogs.
\7\ The best available abundance estimate and Nmin are likely an underestimate for the entire stock because it is based upon a survey that covered only
  a small portion of the stock's range. PBR for this stock is undetermined due to this estimate being older than 8 years.
\8\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys.
\9\ Reliable population estimate for the entire stock not available. PBR is based upon the negatively biased Nmin for bearded seals in the U.S. portion
  of the stock.
\10\ A reliable population estimate for the entire stock is not available. Using a sub-sample of data collected from the U.S portion of the Bering Sea,
  an abundance estimate of 171,418 ringed seals has been calculated, but this estimate does not account for availability bias due to seals in the water
  or in the shore fast ice zone at the time of the survey. The actual number of ringed seals in the U.S. portion of the Bering Sea is likely much
  higher. Using the Nmin based upon this negatively biased population estimate, the PBR is calculated to be 4,755 seals, although this is also a
  negatively biased estimate.

    As indicated above, all 11 species (with 12 managed stocks) in 
Table 2 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. All species that could 
potentially occur in the proposed survey areas are included in Table 3-
1 of USACE's IHA application. While these species could occur in the

[[Page 27468]]

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. Cuvier's beaked whale, Central 
North Pacific humpback whale, Dall's porpoise, harbor seal, Pacific 
white-sided dolphin, sperm whale, Stejneger's beaked whale, blue whale, 
Western North Pacific gray whale, bowhead whale, North Pacific right 
whale, sei whale, Northern fur seal could all occur in the project 
area. We do not anticipate take of Cuvier's beaked whale, Cook Inlet 
beluga whale, Dall's porpoise, Pacific white-sided dolphin, sperm 
whale, Stejneger's beaked whale, blue whale, and Western North Pacific 
gray whale as these species' and stocks' ranges generally do not extend 
as far north as Nome. While it is possible that beluga whales from the 
Eastern Chukchi Sea and Beaufort Sea stocks could occur in the project 
area during the winter, spring, and fall, as both stocks migrate 
between the Bering and Beaufort seas (Citta et al. 2017), animals from 
the Beaufort Sea stock depart the Bering Sea in early spring, migrate 
through the Chukchi Sea and into the Canadian waters of the Beaufort 
Sea where they remain in the summer and fall, and return to the Bering 
Sea in late fall (NMFS 2022c; i.e., are generally not expected to occur 
in the project area during the planned work period). Animals from the 
Eastern Chukchi Sea stock depart the Bering Sea in late spring and 
early summer, migrate through the Chukchi Sea and into the western 
Beaufort Sea where they remain in the summer, and return to the Bering 
Sea in the fall (NMFS 2022c). Tagging data from Citta et al. (2017) 
found that belugas from the Eastern Chukchi Sea and Beaufort Sea stocks 
moved into the central and southern Bering Sea during winter months, 
but did not move into Norton Sound (Citta et al. 2017). Therefore, 
given that both stocks are already unlikely to occur in the project 
area during most or all of the work period, and the animals in Citta et 
al. (2017) did not enter Norton Sound, animals from these stocks are 
not anticipated to be taken by project activities. Bowhead whale, North 
Pacific right whale, sei whale, Northern fur seal, fin whale, Western 
North Pacific humpback whale, are considered rare in Nome. While some 
of the species or stocks listed herein could occur on the vessel 
transit route, as noted above, we do not anticipate take of marine 
mammals due to vessel transit.
    In addition, the Pacific walrus may be found in Nome, AK. However, 
Pacific walrus (Odobenus rosmarus divergens) are managed by the U.S. 
Fish and Wildlife Service and are not considered further in this 
document.
Gray Whale
    Eastern North Pacific gray whales occur in the project area, though 
they are not anticipated to occur in high numbers. Most whales in this 
stock spend the summer and fall months feeding in the Chukchi, 
Beaufort, and northwestern Bering Seas and winter in Baja California, 
Mexico (Carretta et al. 2019). Eastern North Pacific gray whales have 
been experiencing an Unusual Mortality Event (UME) since 2019 when 
large numbers of whales began stranding from Mexico to Alaska. As of 
March 14, 2023, approximately 307 gray whales have stranded in the U.S. 
and 633 total throughout the U.S., Canada, and Mexico since 2019 (NOAA 
2023). Preliminary necropsy results conducted on a subset of the whales 
indicated that many whales showed signs of nutritional stress, however, 
these findings are not consistent across all of the whales examined 
(NOAA 2023). This UME is ongoing and similar to that of 1999 and 2000 
when large numbers of gray whales stranded along the eastern Pacific 
coast (Moore et al. 2001; Gulland et al. 2005). Oceanographic factors 
limiting food availability for whales was identified as a likely cause 
of the prior UME and may also be influencing the current UME (LeBouef 
et al. 2000; Moore et al. 2001; Minobe 2002; Gulland et al. 2005).
Minke Whale
    Minke whales occur in polar, temperate, and tropical waters 
worldwide in a range extending from the ice edge in the Arctic during 
the summer to near the equator during winter. Minke whales in Alaska 
are considered migratory and typically occur in the Arctic during 
summer months and near the equator during winter months (NMFS 2022g).
Killer Whale
    Killer whales occur in every ocean in the world and are the most 
widely distributed of all cetaceans. Along the west coast of North 
America, killer whales occur along the entire Alaska coast (Braham and 
Dahlheim 1982). Killer whales that occur in Norton Sound are likely 
following seasonal movements of whales and pinnipeds.
Beluga Whale
    Five beluga whale stocks occur in Alaska: The Eastern Chukchi Sea 
Stock, the Beaufort Sea Stock, the Eastern Bering Sea Stock, the 
Bristol Bay Stock, and the Cook Inlet Stock. While each stock is unique 
and isolated from one another genetically and/or physically, there is 
some crossover of the Eastern Chukchi Sea and the Eastern Bering Sea 
Stock during the late summer. Beluga whales in the project area are 
anticipated to be from the Eastern Bering Sea stock. The Eastern Bering 
Sea stock remains in the Bering Sea and migrates south near Bristol Bay 
in winter and returns north to Norton Sound and the mouth of the Yukon 
River in summer (Suydam 2009; Hauser et al. 2014; Citta et al. 2017; 
Lowry et al. 2019).
    Beluga whales use Norton Sound during the entire open-water season, 
generally moving to southern Bering Sea waters during winter due to 
high ice concentrations in Norton Sound. During the spring and summer, 
beluga whales tend to concentrate in the eastern half of the Sound 
(Oceana and Kawerak 2014), but the whales may be seen migrating in 
large numbers close to the shoreline near Nome in late autumn (ADFG 
2012). Jewett (1997) stated beluga whales ``appear nearshore with the 
onset of herring spawning in early summer and feed on these as well as 
a wide variety of other fish congregating or migrating nearshore.'' 
They are often seen passing very close to the end of the Nome causeway 
during the fall migration and have been occasionally spotted within the 
Nome Outer Basin (USACE personal communication with Charlie Lean, 
2019). Large groups of beluga have been observed in fall in front of 
Cape Nome and near Topkok (Oceana and Kawerak 2014).
    Norton Sound includes three biologically important areas (BIAs) 
identified as important for feeding by Eastern Bering Sea belugas 
(Brower et al. 2023). One of these BIAs overlaps the project area. The 
BIA that overlaps the project area is active May through November, 
which overlaps USACE's proposed work window (May to October). The BIA 
scored a 2 for importance, intensity, data support and boundary 
certainty scores, indicating that it is of moderate importance, has 
moderately certain boundaries, and moderate data to support the 
identification of the BIA (see Harrison et al. (2023) for additional 
information about the scoring process used to identify BIAs). The BIA 
was identified as having dynamic spatiotemporal variability.
Harbor Porpoise
    The Bering Sea stock of harbor porpoise occurs within the project 
area, ranging from throughout the Aleutian Islands and into all waters 
north of Unimak Pass. The harbor porpoise

[[Page 27469]]

frequents nearshore waters and coastal embayments throughout their 
range, including bays, harbors, estuaries, and fjords less than 650 ft 
(198 m) deep (NMFS 2018g).
Bearded Seal
    Bearded seals prefer moving ice and open water over relatively 
shallow seafloors. They are closely associated with ice, preferring to 
winter in the Bering Sea and summer along the pack ice edge in the 
Chukchi Sea, although many summer in nearshore waters of the Beaufort 
Sea (NMFS 2022a). Pupping occurs on ice floes primarily in May in the 
Bering and Chukchi seas. Bearded seals feed primarily at or near the 
seabed, on benthic invertebrates, and demersal fish. Spring surveys 
conducted in 1999 and 2000 along the Alaska coast indicate that bearded 
seals are typically more abundant 20-100 nmi (37--185 km) from shore, 
except for high nearshore concentrations to the south of Kivalina 
(Bengtson et al. 2000 and 2005; Simpkins et al. 2003). Many seals that 
winter in the Bering Sea move north through the Bering Strait from late 
April through June and spend the summer in the Chukchi Sea (Burns 1967, 
1981).
    Bearded seals congregate at the open water found near Cape Nome and 
Sledge Island in winter and spring (Oceana and Kawerak 2014). Juvenile 
bearded seals may remain in open water during the summer, feeding in 
lagoons and rivers, but older individuals migrate north with the 
retreating pack ice. Juvenile bearded seals have been observed hauled 
out on land along lagoons and rivers in some areas of Alaska, including 
in the Bering Strait region in summer to early fall (Gadamus et al. 
2015; Huntington et al. 2015). In addition, satellite tracking data 
obtained from juvenile bearded seals tagged in Alaska during 2014 to 
2018 indicate that during the open-water period (July to October), 
about half of the seals that hauled out used terrestrial sites located 
south of the ice edge in Kotzebue Sound and Norton Sound whereas other 
seals remained near the ice edge and hauled out on ice (Olnes et al. 
2020).
    Critical habitat for the bearded seal was designated in May 2022 
and includes marine waters off the coast of Nome (87 FR 19180; April 1, 
2022). Essential features established by NMFS for conservation of the 
bearded Beringia Distinct Population Segment (DPS) include (1) Sea ice 
habitat suitable for whelping and nursing, which is defined as areas 
with waters 200 m or less in depth containing pack ice of at least 25 
percent concentration and providing bearded seals access to hose waters 
from the ice; (2) Sea ice habitat suitable as a platform for molting, 
which is defined as areas with waters 200 m or less in depth containing 
pack ice of at least 15 percent concentration and providing bearded 
seals access to those waters from the ice, and (3) Primary prey 
resources to support bearded seals: Waters 200 m or less in depth 
containing benthic organisms, including epifaunal and infaunal 
invertebrates, and demersal fishes.
    Since June 1, 2018, elevated ice seal strandings (bearded, ringed 
and spotted seals) have occurred in the Bering and Chukchi seas in 
Alaska. This event was declared an Unusual Mortality Event (UME), but 
is currently considered non-active and is pending closure. Given that 
the UME is non-active, it is not discussed further as it relates to 
bearded seals.
Ringed Seal
    In winter and early spring when sea ice is at its maximum coverage, 
ringed seals occur in the northern Bering Sea (including Norton Sound), 
and throughout the Chukchi and Beaufort Seas. They occur as far south 
as Bristol Bay in years of extensive ice coverage (Muto et al. 2022) 
but generally are not abundant south of Norton Sound except in 
nearshore areas (Frost 1985, 1988).
    Near Nome, ringed seals often occur in the open water offshore from 
Cape Nome and Safety Sound (Oceana and Kawerak 2014). Surveys conducted 
in the Bering Sea in the spring of 2012 and 2013 documented numerous 
ringed seals in both nearshore and offshore habitat extending south of 
Norton Sound (79 FR 73010, December 9, 2014; Muto et al. 2022).
    Critical habitat for the ringed seal was designated in May 2022 and 
include marine waters within one specific area in the Bering, Chukchi, 
and Beaufort seas including waters off the coast of Nome (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.
    Since June 1, 2018, elevated ice seal strandings (bearded, ringed 
and spotted seals) have occurred in the Bering and Chukchi seas in 
Alaska. This event was declared an Unusual Mortality Event (UME), but 
is currently considered non-active and is pending closure. Given that 
the UME is non-active, it is not discussed further as it relates to 
ringed seals.
Spotted Seal
    From late fall through spring, spotted seal habitat use is 
primarily associated with seasonal sea ice. Most spotted seals spend 
the rest of the year making periodic foraging trips from haulout sites 
onshore or on sea ice (NMFS 2022b).
    Most summer and fall concentrations of Norton Sound spotted seals 
are in the eastern portion of the Sound, where herring and small cod 
are more abundant. Spotted seals are reportedly more sensitive to human 
disturbances than other seals and have been displaced from some haulout 
and feeding areas due to such disturbance. However, spotted seals are 
regularly seen at the Port of Nome and within the harbor area, 
especially before or after the busy summer season, sometimes hauled out 
on the beach or breakwater (USACE personal communication with Charlie 
Lean, 2019). The existing Outer Basin at the Port of Nome, since the 
construction of the new entrance channel and east breakwater in 2006, 
has become the new river mouth and a sort of artificial lagoon of the 
Snake River. Seals and other marine mammals tend to congregate there, 
especially in the autumn (Oceana and Kawerak 2014). Spotted seals are 
an important subsistence species for Alaska Native hunters.
    Since June 1, 2018, elevated ice seal strandings (bearded, ringed 
and spotted seals) have occurred in the Bering and Chukchi seas in 
Alaska. This event was declared an Unusual Mortality Event (UME), but 
is currently considered non-active and is pending closure. Given that 
the UME is non-active, it is not discussed further.
Steller Sea Lion
    Steller sea lions in the project area are anticipated to be from 
the Western stock, which includes all Steller sea

[[Page 27470]]

lions originating from rookeries west of Cape Suckling (144[deg] West 
longitude). The centers of abundance and distribution for western DPS 
Steller sea lions are located in the Gulf of Alaska and Aleutian 
Islands. At sea, Steller sea lions commonly occur near the 656-foot 
(200-meter) depth contour but have been found from nearshore to well 
beyond the continental shelf (Kajimura and Loughlin 1988). Sea lions 
move offshore to pelagic waters for feeding excursions.
    Observations suggest that Steller sea lions are becoming common in 
the northern Bering Sea, including Norton Sound. Sea lions have been 
spotted hauling out in small numbers at Sledge Island, about 22 miles 
(mi; 35.4 km) west of Nome. Their change in range is perhaps attributed 
to climate-change-driven, northward movement of pelagic fish prey 
species, such as Pacific cod (USACE personal communication with Gay 
Sheffield, 2018).
    The nearest Steller sea lion critical habitat to the Port of Nome 
is on the east shore of St. Lawrence Island, about 140 mi (225.3 km) to 
the southwest. However, Steller sea lions, especially juveniles and 
non-breeding males, can range through waters far beyond their primary 
use areas.
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 decibel (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 3.

            Table 3--Marine Mammal Hearing Groups (NMFS 2018)
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, 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)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 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 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

    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.
    Acoustic effects on marine mammals during the specified activities 
can occur from vibratory and impact pile driving. The effects of 
underwater noise from USACE's proposed activities have the potential to 
result in Level B harassment only of marine mammals.

Description of Sound Sources

    The marine soundscape is comprised 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 (ANSI 1995). The sound level of an area is 
defined by the total acoustical energy being generated by known and 
unknown sources. These sources 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 
decibels (dB) from day to day

[[Page 27471]]

(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.
    In-water construction activities associated with the project would 
include impact and vibratory pile driving and vibratory pile removal. 
The sounds produced by these activities fall into one of two general 
sound types: impulsive and non-impulsive. Impulsive sounds (e.g., 
explosions, sonic booms, impact pile driving) are typically transient, 
brief (less than 1 second), broadband, and consist of high peak sound 
pressure with rapid rise time and rapid decay (ANSI 1986; NIOSH 1998; 
NMFS 2018). Non-impulsive sounds (e.g., machinery operations such as 
drilling or dredging, vibratory pile driving, underwater chainsaws, and 
active sonar systems) can be broadband, narrowband or tonal, brief or 
prolonged (continuous or intermittent), and typically do not have the 
high peak sound pressure with raid rise/decay time that impulsive 
sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The distinction between 
impulsive and non-impulsive sound sources 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).
    USACE plans to use two types of hammers, impact, and vibratory. 
Impact hammers operate by repeatedly dropping and/or pushing a heavy 
piston onto a pile to drive the pile into the substrate. Sound 
generated by impact hammers is considered impulsive. Vibratory hammers 
install piles by vibrating them and allowing the weight of the hammer 
to push them into the sediment. Vibratory hammers produce non-
impulsive, continuous sounds. Vibratory hammering generally produces 
sounds pressure levels (SPLs) 10 to 20 dB lower than impact pile 
driving of the same-sized pile (Oestman et al. 2009). Rise time is 
slower, reducing the probability and severity of injury, and sound 
energy is distributed over a greater amount of time (Nedwell and 
Edwards 2002; Carlson et al. 2005).
    The likely or possible impacts of USACE's proposed activities on 
marine mammals could be generated from both non-acoustic and acoustic 
stressors. Potential non-acoustic stressors include the physical 
presence of the equipment, vessels, and personnel; however, we expect 
that any animals that approach the project site(s) close enough to be 
harassed due to the presence of equipment or personnel would be within 
the Level A or Level B harassment zones from pile driving/removal and 
would already be subject to harassment from the in-water activities. 
Therefore, any impacts to marine mammals are expected to primarily be 
acoustic in nature. Acoustic stressors include heavy equipment 
operation during pile installation and removal.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving and removal equipment is the primary 
means by which marine mammals may be harassed from USACE's specified 
activities. In general, animals exposed to natural or anthropogenic 
sound may experience physical and psychological effects, ranging in 
magnitude from none to severe (Southall et al. 2007). Generally, 
exposure to pile driving and removal and other construction noise has 
the potential to result in auditory threshold shifts and behavioral 
reactions (e.g., avoidance, temporary cessation of foraging and 
vocalizing, changes in dive behavior). Exposure to anthropogenic noise 
can also lead to non-observable physiological responses such as an 
increase in stress hormones. Additional noise in a marine mammal's 
habitat can mask acoustic cues used by marine mammals to carry out 
daily functions such as communication and predator and prey detection. 
The effects of pile driving and demolition noise on marine mammals are 
dependent on several factors, including, but not limited to, sound type 
(e.g., impulsive vs. non-impulsive), the species, age and sex class 
(e.g., adult male vs. mother with calf), duration of exposure, the 
distance between the pile and the animal, received levels, behavior at 
time of exposure, and previous history with exposure (Wartzok et al. 
2003; Southall et al. 2007). Here we discuss physical auditory effects 
(threshold shifts) followed by behavioral effects and potential impacts 
on habitat.
    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). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS (2018), 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 
and vocalization 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).
    Permanent Threshold Shift (PTS)--NMFS defines PTS 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 2018). Available data from 
humans and other terrestrial mammals indicate that a 40 dB threshold 
shift approximates PTS onset (see Ward et al. 1958, 1959; Ward 1960; 
Kryter et al. 1966; Miller 1974; Henderson et al. 2008). PTS levels for 
marine mammals are estimates, because there are limited empirical data 
measuring PTS in marine mammals (e.g., Kastak et al. 2008), largely due 
to the fact that, for various ethical reasons, experiments involving 
anthropogenic noise exposure at levels inducing PTS are not typically 
pursued or authorized (NMFS 2018).
    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 2018). Based on data from cetacean TTS 
measurements (see Southall et al. 2007), a TTS of 6 dB is considered 
the minimum threshold shift clearly larger than any day-to-day or 
session-to-session variation in a subject's normal hearing ability 
(Schlundt et al. 2000; Finneran et al. 2000, 2002). As described in 
Finneran (2016), 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.
    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 Masking, 
below). For example, a marine

[[Page 27472]]

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 when the animal is traveling through the open ocean, 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. We note that 
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 cost.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019) for summaries). 
For cetaceans, published data on the onset of TTS are limited to the 
captive bottlenose dolphin (Tursiops truncatus), beluga whale, harbor 
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis), 
and for pinnipeds in water, measurements of TTS are limited to harbor 
seals (Phoca vitulina), elephant seals (Mirounga angustirostris), and 
California sea lions (Zalophus californianus). These studies examine 
hearing thresholds measured in marine mammals before and after exposure 
to intense sounds. The difference between the pre-exposure and post-
exposure thresholds can 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, 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, 2019b, 2020a, 2020b). 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; Kastelein et al. 2015a; 
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) and Finneran (2018) describe the 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 (NMFS 2018).
    Activities for this project include impact and vibratory pile 
driving and vibratory pile removal. There would likely be pauses in 
activities producing the sound during each day. Given these pauses and 
the fact that many marine mammals are likely moving through the project 
areas and not remaining for extended periods of time, the potential for 
threshold shift declines.
    Behavioral harassment--Exposure to noise from pile driving and 
removal also has the potential to behaviorally disturb marine mammals. 
Behavioral responses to sound are highly variable and context-specific 
and any reactions depend on numerous intrinsic and extrinsic factors 
(e.g., species, state of maturity, experience, current activity, 
reproductive state, auditory sensitivity, time of day), as well as the 
interplay between factors (e.g., Richardson et al. 1995; Wartzok et al. 
2003; Southall et al. 2007; Weilgart 2007; Archer et al. 2010; Southall 
et al. 2021). If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder 2007; Weilgart 2007; NRC 2005).
    The following subsections provide examples of behavioral responses 
that provide an idea of the variability in behavioral responses that 
would be expected given the differential sensitivities of marine mammal 
species to sound and the wide range of potential acoustic sources to 
which a marine mammal may be exposed. Behavioral responses that could 
occur for a given sound exposure should be determined from the 
literature that is available for each species, or extrapolated from 
closely related species when no information exists, along with 
contextual factors. Available studies show wide variation in response 
to underwater sound; therefore, it is difficult to predict specifically 
how any given sound in a particular instance might affect marine 
mammals perceiving the signal. There are broad categories of potential 
response, which we describe in greater detail here, that include 
alteration of dive behavior, alteration of foraging behavior, effects 
to respiration, interference with or alteration of vocalization, 
avoidance, and flight.
    Pinnipeds may increase their haul out time, possibly to avoid in-
water disturbance (Thorson and Reyff 2006). Behavioral reactions can 
vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al. 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). In 
general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem to be less responsive to exposure to industrial 
sound than most cetaceans.
    Alteration of Feeding Behavior--Disruption of feeding behavior can 
be difficult to correlate with anthropogenic sound exposure, so it is 
usually inferred by observed displacement from known foraging areas, 
the appearance of secondary indicators (e.g., bubble nets or sediment 
plumes), or changes in dive behavior. As for other types of behavioral 
response, the frequency, duration, and temporal pattern of signal 
presentation, as well as differences in species sensitivity, are likely 
contributing factors to differences in response in any given 
circumstance (e.g., Croll et al. 2001; Nowacek et al. 2004; Madsen et 
al. 2006; Yazvenko et al. 2007; Melc[oacute]n et al. 2012). In 
addition, behavioral state of the animal plays a role in the type and 
severity of a behavioral response, such as disruption to foraging 
(e.g., Silve et al. 2016; Wensveen et al. 2017). A determination of 
whether foraging

[[Page 27473]]

disruptions incur fitness consequences would require information on or 
estimates of the energetic requirements of the affected individuals and 
the relationship between prey availability, foraging effort and 
success, and the life history stage of the animal. Goldbogen et al. 
(2013) indicate that disruption of feeding and displacement could 
impact individual fitness and health. However, for this to be true, we 
would have to assume that an individual could not compensate for this 
lost feeding opportunity by either immediately feeding at another 
location, by feeding shortly after cessation of acoustic exposure, or 
by feeding at a later time. There is no indication this is the case, 
particularly since unconsumed prey would likely still be available in 
the environment in most cases following the cessation of acoustic 
exposure. Information on or estimates of the energetic requirements of 
the individuals and the relationship between prey availability, 
foraging effort and success, and the life history stage of the animal 
will help better inform a determination of whether foraging disruptions 
incur fitness consequences.
    Avoidance--Avoidance is the displacement of an individual from an 
area or migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al. 1995). Avoidance is qualitatively 
different from the flight response, but also differs in the magnitude 
of the response (i.e., directed movement, rate of travel, etc.). Often 
avoidance is temporary, and animals return to the area once the noise 
has ceased. Acute avoidance responses have been observed in captive 
porpoises and pinnipeds exposed to a number of different sound sources 
(Kastelein et al. 2001; Finneran et al. 2003; Kastelein et al. 2006a; 
Kastelein et al. 2006b; Kastelein et al. 2015b; Kastelein et al. 2015c; 
Kastelein et al. 2018). Short-term avoidance of seismic surveys, low 
frequency emissions, and acoustic deterrents have also been noted in 
wild populations of odontocetes (Bowles et al. 1994; Goold 1996; Goold 
and Fish 1998; Morton and Symonds 2002; Hiley et al. 2021) and to some 
extent in mysticetes (Malme et al. 1984; McCauley et al. 2000; Gailey 
et al. 2007). Longer-term displacement is possible, however, which may 
lead to changes in abundance or distribution patterns of the affected 
species in the affected region if habituation to the presence of the 
sound does not occur (e.g., Blackwell et al. 2004; Bejder et al. 2006; 
Teilmann et al. 2006).
    Forney et al. (2017) described the potential effects of noise on 
marine mammal populations with high site fidelity, including 
displacement and auditory masking. In cases of Western gray whales 
(Eschrichtius robustus) (Weller et al. 2006) and beaked whales (Ziphius 
cavirostris), anthropogenic effects in areas where they are resident or 
exhibit site fidelity could cause severe biological consequences, in 
part because displacement may adversely affect foraging rates, 
reproduction, or health, while an overriding instinct to remain in the 
area could lead to more severe acute effects. Avoidance of overlap 
between disturbing noise and areas and/or times of particular 
importance for sensitive species may be critical to avoiding 
population-level impacts because (particularly for animals with high 
site fidelity) there may be a strong motivation to remain in the area 
despite negative impacts.
    Flight Response--A flight response is a dramatic change in normal 
movement to a directed and rapid movement away from the perceived 
location of a sound source. The flight response differs from other 
avoidance responses in the intensity of the response (e.g., directed 
movement, rate of travel). Relatively little information on flight 
responses of marine mammals to anthropogenic signals exist, although 
observations of flight responses to the presence of predators have 
occurred (Connor and Heithaus 1996). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (Evans and England 2001). There are limited data on 
flight response for marine mammals in water; however, there are 
examples of this response in species on land. For instance, the 
probability of flight responses in Dall's sheep Ovis dalli dalli (Frid, 
2003), hauled out ringed seals (Born et al. 1999), Pacific brant 
(Branta bernicla nigricans), and Canada geese (B. canadensis) increased 
as a helicopter or fixed-wing aircraft more directly approached groups 
of these animals (Ward et al. 1999). However, it should be noted that 
response to a perceived predator does not necessarily invoke flight 
(Ford and Reeves 2008), and whether individuals are solitary or in 
groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been observed in marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates and efficiency (e.g., 
Beauchamp and Livoreil 1997; Fritz et al. 2002; Purser and Radford 
2011). In addition, chronic disturbance can cause population declines 
through reduction of fitness (e.g., decline in body condition) and 
subsequent reduction in reproductive success, survival, or both (e.g., 
Harrington and Veitch 1992; Daan et al. 1996; Bradshaw et al. 1998).
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al. 2007). 
Consequently, a behavioral response lasting less than 1 day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al. 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    To assess the strength of behavioral changes and responses to 
external sounds and SPLs associated with changes in behavior, Southall 
et al. (2007) developed and utilized a severity scale, which is a 10 
point scale ranging from no effect (labeled 0), effects not likely to 
influence vital rates (low; labeled from 1 to 3), effects that could 
affect vital rates (moderate; labeled 4 to 6), to effects that were 
thought likely to influence vital rates (high; labeled 7 to 9). 
Southall et al. (2021) updated the severity scale by integrating 
behavioral context (i.e., survival, reproduction, and foraging) into 
severity assessment. For non-impulsive sounds (i.e., similar to the 
sources used during the proposed action), data suggest that exposures 
of pinnipeds to sources 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

[[Page 27474]]

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).
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle 1950; Moberg 
2000). In many cases, an animal's first and sometimes most economical 
(in terms of energetic costs) response is behavioral avoidance of the 
potential stressor. Autonomic nervous system responses to stress 
typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness. Neuroendocrine stress responses often involve the 
hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine 
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, altered metabolism, 
reduced immune competence, and behavioral disturbance (e.g., Moberg 
1987; Blecha 2000). Increases in the circulation of glucocorticoids are 
also equated with stress (Romano et al. 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the 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 functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and 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). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker 2000; Romano 
et al. 2002b) and, more rarely, studied in wild populations (e.g., 
Romano et al. 2002a). For example, Rolland et al. (2012) found that 
noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC 2003), however 
distress is an unlikely result of these projects based on observations 
of marine mammals during previous, similar projects.
    Masking--Sound can disrupt behavior through masking, or interfering 
with, an animal's ability to detect, recognize, or discriminate between 
acoustic signals of interest (e.g., those used for intraspecific 
communication and social interactions, prey detection, predator 
avoidance, navigation; Richardson et al. 1995). Masking occurs when the 
receipt of a sound is interfered with by another coincident sound at 
similar frequencies and at similar or higher intensity, and may occur 
whether the sound is natural (e.g., snapping shrimp, wind, waves, 
precipitation) or anthropogenic (e.g., pile driving, 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 of natural sounds can result when human activities 
produce high levels of background sound at frequencies important to 
marine mammals. Conversely, if the background level of underwater sound 
is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with pile driving 
and removal that have the potential to cause behavioral harassment, 
depending on their distance from pile driving activities. Cetaceans are 
not expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA.
    Airborne noise would primarily be an issue for pinnipeds that are 
swimming or hauled out near the project site within the range of noise 
levels elevated above the acoustic criteria. We recognize that 
pinnipeds in the water could be exposed to airborne sound that may 
result in behavioral harassment when looking with their heads above 
water. Most likely, airborne sound would cause behavioral responses 
similar to those discussed above in relation to underwater sound. For 
instance, anthropogenic sound could cause hauled out pinnipeds to 
exhibit changes in their normal behavior, such as reduction in 
vocalizations, or cause them to temporarily abandon the area and move 
further from the source. However, these animals would likely previously 
have been `taken' because of exposure to underwater sound above the 
behavioral harassment thresholds, which are generally larger than those 
associated with airborne sound. Thus, the behavioral harassment of 
these animals is already accounted for in these estimates of potential 
take. Therefore, we do not believe that authorization of incidental 
take resulting from airborne sound for pinnipeds is warranted, and 
airborne sound is not discussed further.

Marine Mammal Habitat Effects

    USACE's proposed construction activities could have localized, 
temporary impacts on marine mammal habitat, including prey, by 
increasing in-water sound pressure levels and slightly decreasing water 
quality. Increased noise levels may affect acoustic habitat (see 
Masking discussion above) and adversely affect marine mammal prey in 
the vicinity of the project areas (see discussion below). Elevated 
levels of underwater noise would ensonify the project areas where both 
fishes and mammals occur and could affect foraging success. 
Additionally, marine mammals may avoid the area during construction; 
however, displacement due to noise is expected to be temporary and is 
not expected to result in long-term effects to the individuals or 
populations.

[[Page 27475]]

In-Water Construction Effects on Potential Foraging Habitat

    The total seafloor area likely impacted by the project is 
relatively small compared to the available habitat in Norton Sound and 
nearby areas in the Bering Sea. Avoidance by potential prey (i.e., 
fish) of the immediate area due to the temporary loss of this foraging 
habitat is possible. The duration of fish and marine mammal avoidance 
of this area after pile driving stops is unknown, but a rapid return to 
normal recruitment, distribution, and behavior is anticipated. Any 
behavioral avoidance by fish or marine mammals of the disturbed area 
would still leave significantly large areas of fish and marine mammal 
foraging habitat in the nearby vicinity.
    A temporary and localized increase in turbidity near the seafloor 
would occur in the immediate area surrounding the area where piles are 
installed or removed. In general, turbidity associated with pile 
installation is localized to about a 25-ft (7.6 m) radius around the 
pile (Everitt et al. 1980). Turbidity and sedimentation effects are 
expected to be short-term, minor, and localized. Cetaceans are not 
expected to be close enough to the pile driving areas to experience 
effects of turbidity, and any pinnipeds could avoid localized areas of 
turbidity. Therefore, we expect the impact from increased turbidity 
levels to be discountable to marine mammals. Furthermore, pile driving 
and removal at the project site would not obstruct movements or 
migration of marine mammals.

Effects on Potential Prey

    Sound may affect marine mammals through impacts on the abundance, 
behavior, or distribution of prey species (e.g., fish). Marine mammal 
prey varies by species, season, and location. Here, we describe studies 
regarding the effects of noise on known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick and Mann 1999; Fay 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al. 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds that are especially strong and/or intermittent 
low-frequency sounds, and behavioral responses such as flight or 
avoidance are the most likely effects. Short duration, sharp sounds can 
cause overt or subtle changes in fish behavior and local distribution. 
The reaction of fish to noise depends on the physiological state of the 
fish, past exposures, motivation (e.g., feeding, spawning, migration), 
and other environmental factors. Hastings and Popper (2005) identified 
several studies that suggest fish may relocate to avoid certain areas 
of sound energy. Additional studies have documented effects of pile 
driving on fish; several are based on studies in support of large, 
multiyear bridge construction projects (e.g., Scholik and Yan 2001, 
2002; Popper and Hastings 2009). Several studies have demonstrated that 
impulse sounds might affect the distribution and behavior of some 
fishes, potentially impacting foraging opportunities or increasing 
energetic costs (e.g., Fewtrell and McCauley 2012; Pearson et al. 1992; 
Skalski et al. 1992; Santulli et al. 1999; Paxton et al. 2017). 
However, some studies have shown no or slight reaction to impulse 
sounds (e.g., Pena et al. 2013; Wardle et al. 2001; Jorgenson and 
Gyselman 2009).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al. 2012b; Casper et al. 2013).
    The most likely impact to fishes from pile driving activities at 
the project area would be temporary behavioral avoidance of the area. 
The duration of fish avoidance of this area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution, and 
behavior is anticipated.
    Construction activities have the potential to have adverse impacts 
on forage fish in the project area in the form of increased turbidity. 
Forage fish form a significant prey base for many marine mammal species 
that occur in the project area. Turbidity within the water column has 
the potential to reduce the level of oxygen in the water and irritate 
the gills of prey fish in the proposed project area. However, fish in 
the proposed project area would be able to move away from and avoid the 
areas where increase turbidity may occur. Given the limited area 
affected and ability of fish to move to other areas, any effects on 
forage fish are expected to be minor or negligible.
    In summary, given the short daily duration of sound associated with 
individual pile driving and removal events and the relatively small 
areas being affected, pile driving and removal activities associated 
with the proposed actions are not likely to have a permanent, adverse 
effect on any fish habitat, or populations of fish species. Any 
behavioral avoidance by fish of the disturbed area would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity. Thus, we conclude that impacts of the specified 
activities are not likely to have more than short-term adverse effects 
on any prey habitat or populations of prey species. Further, any 
impacts to marine mammal habitat are not expected to result in 
significant or long-term consequences for individual marine mammals, or 
to contribute to adverse impacts on their populations.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would be by Level B harassment only, in the form 
of disruption of behavioral patterns and/or

[[Page 27476]]

TTS for individual marine mammals resulting from exposure to 
construction activities. Based on the nature of the activity and the 
anticipated effectiveness of the mitigation measures (i.e., 
implementation of shutdown zones) discussed in detail below in the 
Proposed Mitigation section, 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 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 proposed 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 PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al. 2007, 2021; Ellison et al. 2012). Based 
on what the available science indicates and the practical need to use a 
threshold based on a metric that is both predictable and measurable for 
most activities, NMFS typically uses a generalized acoustic threshold 
based on received level to estimate the onset of behavioral harassment. 
NMFS generally predicts that marine mammals are likely to be 
behaviorally harassed in a manner considered to be Level B harassment 
when exposed to underwater anthropogenic noise above root-mean-squared 
pressure received levels (RMS SPL) of 120 dB (referenced to 1 
micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving) and above RMS SPL 160 dB re 1 [mu]Pa for non-explosive 
impulsive (e.g., seismic airguns) or intermittent (e.g., scientific 
sonar) sources. Generally speaking, Level B harassment take estimates 
based on these behavioral harassment thresholds are expected to include 
any likely takes by TTS as, in most cases, the likelihood of TTS occurs 
at distances from the source less than those at which behavioral 
harassment is likely. TTS of a sufficient degree can manifest as 
behavioral harassment, as reduced hearing sensitivity and the potential 
reduced opportunities to detect important signals (conspecific 
communication, predators, prey) may result in changes in behavior 
patterns that would not otherwise occur.
    USACE's activity includes the use of continuous (vibratory pile 
driving) and impulsive (impact pile driving) sources, and therefore the 
RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are applicable.
    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). USACE's 
proposed activity includes the use of impulsive (impact pile driving) 
and non-impulsive (vibratory pile driving) sources.
    These thresholds are provided in the Table 4. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                                         Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      PTS onset acoustic thresholds \*\ (received level)
            Hearing group            -------------------------------------------------------------------------------------------------------------------
                                                                    Impulsive                                               Non-impulsive
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........  Cell 1: Lpk,flat: 219 dB; LE,LF,24h: 183 dB.........................  Cell 2: LE,LF,24h: 199 dB.
Mid-Frequency (MF) Cetaceans........  Cell 3: Lpk,flat: 230 dB; LE,MF,24h: 185 dB.........................  Cell 4: LE,MF,24h: 198 dB.
High-Frequency (HF) Cetaceans.......  Cell 5: Lpk,flat: 202 dB; LE,HF,24h: 155 dB.........................  Cell 6: LE,HF,24h: 173 dB.
Phocid Pinnipeds (PW) (Underwater)..  Cell 7: Lpk,flat: 218 dB; LE,PW,24h: 185 dB.........................  Cell 8: LE,PW,24h: 201 dB.
Otariid Pinnipeds (OW) (Underwater).  Cell 9: Lpk,flat: 232 dB; LE,OW,24h: 203 dB.........................  Cell 10: LE,OW,24h: 219 dB.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive
  sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be
  considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE) has a reference value of 1[micro]Pa\2\s.
  In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure is
  defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is being
  included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with
  cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW
  pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds 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 acoustic thresholds will be exceeded.


[[Page 27477]]

 Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., pile driving and removal). The 
maximum (underwater) area ensonified above the thresholds for 
behavioral harassment referenced above is 752 km\2\ (290 mi\2\), and 
the calculated distance to the farthest behavioral harassment isopleth 
is approximately 21.5 km (13.4 mi).
    The project includes vibratory pile installation and removal and 
impact pile driving. Source levels for these activities are based on 
reviews of measurements of the same or similar types and dimensions of 
piles available in the literature. Source levels for each pile size and 
activity are presented in Table 5. Source levels for vibratory 
installation and removal of piles of the same diameter are assumed to 
be the same.

                                                Table 5--Sound Source Levels for Pile Driving Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Vibratory sound source levels                              Impact sound source levels \1\
            Pile type            -----------------------------------------------------------------------------------------------------------------------
                                     SPLRMS        SEL          Peak      Literature source      SPLRMS        SEL          Peak      Literature source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Temporary template piles (Pipe          154.0        144.0          N/A  Caltrans (2020)....        189.0        178.0        203.0  Caltrans (2015).
 piles <=24'').
Alternate Temporary template            150.0        147.0        165.0  Caltrans (2020)....        178.0        166.0        200.0  Caltrans (2020).
 piles (H-piles 14'').
Anchor piles (14'' HP14x89 or           150.0        147.0        165.0  Caltrans (2020)....        178.0        166.0        200.0  Caltrans (2020).
 similar).
Sheet piles (20'' PS31 or               160.7        161.1        171.5  PND (2016, 2020)...        189.0        179.0        205.0  Caltrans (2015).
 similar).
Fender piles (Pipe piles 36'')..        170.0        159.0        191.0  Caltrans (2015)....        193.0        183.0        210.0  Caltrans (2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ USACE anticipates that all piles would be installed/removed using a vibratory hammer. However, if conditions prevent successful installation with a
  vibratory hammer, USACE would use an impact hammer to complete installation.

    Transmission loss (TL) is the decrease in acoustic intensity as an 
acoustic pressure wave propagates out from a source. TL parameters vary 
with frequency, temperature, sea conditions, current, source and 
receiver depth, water depth, water chemistry, and bottom composition 
and topography. The general formula for underwater
TL is:

TL = B * Log10 (R1/R2),

where

TL = transmission loss in dB

B = transmission loss coefficient

R1 = the distance of the modeled SPL from the driven pile, and

R2 = the distance from the driven pile of the initial measurement

    Absent site-specific acoustical monitoring with differing measured 
transmission loss, a practical spreading value of 15 is used as the 
transmission loss coefficient in the above formula. Site-specific 
transmission loss data for the Port of Nome are not available; 
therefore, the default coefficient of 15 is used to determine the 
distances to the Level A harassment and Level B harassment thresholds.
    The ensonified area associated with Level A harassment is more 
technically challenging to predict due to the need to account for a 
duration component. Therefore, NMFS developed an optional User 
Spreadsheet tool to accompany the Technical Guidance that can be used 
to relatively simply predict an isopleth distance for use in 
conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources such as pile driving, the optional User Spreadsheet 
tool predicts the distance at which, if a marine mammal remained at 
that distance for the duration of the activity, it would be expected to 
incur PTS. Inputs used in the optional User Spreadsheet tool, and the 
resulting estimated isopleths, are reported below.

                      Table 6--User Spreadsheet Inputs (Source Levels Provided in Table 5)
----------------------------------------------------------------------------------------------------------------
                                                                               Strikes per
            Pile type                 Installation/       Minutes per pile    pile (impact)     Piles per day
                                         removal          (vibratory) \1\          \1\
----------------------------------------------------------------------------------------------------------------
Temporary template piles (Pipe     Installation.......  10.................              20  20.
 piles <=24'').
                                   Removal............  10.................  ..............  20.
(Alternate) Temporary template     Installation.......  10.................              20  (20).
 piles (H-piles 14'').
                                   Removal............  (10)...............  ..............  (20).
Anchor piles (14'' HP14x89 or      Installation.......  10.................              20  20.
 similar).
Sheet piles (20'' PS31 or          Installation.......  10 (20 per pair)...              10  28 (14 pairs).
 similar).
Fender piles (Pipe piles 36'')...  Installation.......  10.................              20  12.
----------------------------------------------------------------------------------------------------------------
\1\ USACE anticipates that all piles would be installed/removed using a vibratory hammer. However, if conditions
  prevent successful installation with a vibratory hammer, USACE would use an impact hammer to complete
  installation.


[[Page 27478]]


       Table 7--Level A Harassment and Level B Harassment Isopleths From Vibratory and Impact Pile Driving
----------------------------------------------------------------------------------------------------------------
                                                      Level A harassment isopleths (m)                Level B
                Pile type                 -------------------------------------------------------   harassment
                                               LF         MF         HF         PW         OW      isopleth (m)
----------------------------------------------------------------------------------------------------------------
                                                    VIBRATORY
----------------------------------------------------------------------------------------------------------------
Temporary template piles (Pipe piles               5         <1          7          3         <1           1,848
 <=24'').................................
(Alternate) Temporary template piles (H-           3         <1          4          2         <1           1,000
 piles 14'').............................
Anchor piles (14'' HP14x89 or similar)...          3         <1          4          2         <1           1,000
Sheet piles (20'' PS31 or similar).......         18          2         27         11         <1           5,168
Fender piles (Pipe piles 36'')...........         43          4         64         26          2          21,544
----------------------------------------------------------------------------------------------------------------
                                                     IMPACT
----------------------------------------------------------------------------------------------------------------
Temporary template piles (Pipe piles             252          9        300        135         10             858
 <=24'').................................
(Alternate) Temporary template piles (H-          40          1         48         21          2             159
 piles 14'').............................
Anchor piles (14'' HP14x89 or similar)...         40          1         48         21          2             159
Sheet piles (20'' PS31 or similar).......        231          8        276        124          9             858
Fender piles (Pipe piles 36'')...........        386         14        459        206         15           1,585
----------------------------------------------------------------------------------------------------------------

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information that 
will inform the take calculations. We describe how the information 
provided is synthesized to produce a quantitative estimate of the take 
that is reasonably likely to occur and proposed for authorization. A 
summary of proposed take, including as a percentage of population for 
each of the species, is shown in Table 9.
Gray Whale
    Various gray whale density and occurrence information is available 
for the Bering, Chukchi, and Beaufort Seas (e.g., Clarke et al. 2020; 
Ferguson et al. 2018a). Ljungblad et al. (1982) and Ljungblad and Moore 
(1983) summarized aerial surveys conducted in the Bering Sea including 
the waters of Norton Sound in the early 1980s. Both reported gray 
whales feeding in large numbers in Norton Sound and waters near St. 
Lawrence Island. During the Chukchi Sea Environmental Studies Program 
(CSESP) a large number of gray whales (n = 55, including 2 calves) were 
observed feeding in late July approximately 130 km from the Port of 
Nome (Lomac-MacNair et al. 2022). During the Quintillion subsea fiber 
optic cable project three sightings of eight total gray whales were 
detected within 60 km of Nome, four during July and four during 
November 2016 (Blees et al. 2017).
    However, NMFS was unable to locate data describing frequency of 
gray whale occurrence or density within the project area or in Norton 
Sound more generally. USACE conducted monitoring at the project site on 
19 calendar days during 2019 and 2021. USACE did not detect gray whales 
during that monitoring, but they are known to occur in Norton Sound and 
have been sighted during previous aerial line-transect surveys in 
Norton Sound (personal communication; Megan Ferguson, February 21, 
2023).
    NMFS estimates that a gray whale or group of gray whales may enter 
the project area periodically throughout the duration of the 
construction period, averaging one gray whale per week. Therefore, 
given the limited information in the project area to otherwise inform a 
take estimate, NMFS proposes to authorize 12 takes by Level B 
harassment of gray whale.
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
especially in combination with the already low frequency of gray whales 
entering the area, implementation of the proposed shutdown zones is 
expected to eliminate the potential for take by Level A harassment of 
gray whale. Therefore, USACE did not request take by Level A harassment 
of gray whale, nor is NMFS is proposing to authorize any.
Minke Whale
    Various minke whale density and occurrence information is available 
for the Bering, Chukchi, and Beaufort Seas (e.g., Clarke et al. 2020; 
Moore et al. 2002). During CSESP surveys (2008-2014), minke whales were 
observed near the Port of Nome (Lomac-MacNair et al. 2022). No minke 
whales were seen during monitoring efforts at Nome during the 2016 
Quintillion subsea fiber optic cable project (Blees et al. 2017). NMFS 
was unable to locate data describing frequency of minke whale 
occurrence, group size, or density within the project area or in Norton 
Sound more generally. USACE did not detect minke whales during its 2019 
and 2021 monitoring, but they are known to occur in Norton Sound and 
have been sighted during previous aerial line-transect surveys in 
Norton Sound (personal communication; Megan Ferguson, February 21, 
2023).
    NMFS estimates that a minke whale may enter the project area 
periodically throughout the duration of the construction period, 
averaging one minke whale per week. Therefore, given the limited 
information in the project area to otherwise inform a take estimate, 
NMFS proposes to authorize 12 takes by Level B harassment of minke 
whale.
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
especially in combination with the already low frequency of minke 
whales entering the area, implementation of the proposed shutdown zones 
is expected to eliminate the potential for take by Level A harassment 
of minke whale. Therefore, USACE did not request take by Level A 
harassment of minke whale, nor is NMFS is proposing to authorize any.
Killer Whale
    Limited information regarding killer whale occurrence in the Nome 
area is available. Waite et al. (2002) estimated 391 (95 percent CI = 
171-894) killer whales of all types in the southeastern Bering Sea 
using line-transect methods and indicates that density of killer whales 
is also high in this area (.0025 whales per km\2\). During the 
Quintillion subsea fiber optic cable project, a single killer whale was 
recorded within 60 km of Nome during July 2016 (Blees et al. 2017). 
USACE did not detect killer

[[Page 27479]]

whales during its 2019 and 2021 monitoring.
    NMFS estimates that 2 groups of 15 killer whales may enter the 
project area over the duration of the construction period. Therefore, 
given the limited information in the project area to otherwise inform a 
take estimate, NMFS conservatively proposes to authorize 30 takes by 
Level B harassment of killer whale (2 groups of 15 animals). NMFS 
anticipates that these takes could occur to the Eastern North Pacific 
Alaska Resident stock, the Eastern North Pacific Gulf of Alaska, 
Aleutian Islands, and Bering Sea Transient stock, or some combination 
of the two.
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
especially in combination with the already low occurrence of killer 
whales in the area, implementation of the proposed shutdown zones is 
expected to eliminate the potential for take by Level A harassment of 
killer whale. Therefore, USACE did not request take by Level A 
harassment of killer whale, nor is NMFS is proposing to authorize any.
Harbor Porpoise
    Moore et al. (2002) reported density estimates for harbor porpoise 
derived from vessel survey data collected on visual line transect 
surveys for cetaceans in the central-eastern Bering Sea (CEBS) in July 
and August 1999 and in the southeastern Bering Sea (SEBS) in June and 
July 2000. Harbor porpoise were seen throughout the coastal (shore to 
50 m) and middle shelf (50-100 m) zones in the SEBS with sighting in 
the coastal zone over four times that of the middle shelf zone. 
Relatively few harbor porpoise were reported in the CEBS. Density for 
harbor porpoise in the CEBS was 0.0035 porpoise/km\2\ and in the SEBS 
was 0.012 animals/km\2\. During the Quintillion subsea fiber optic 
cable project four sightings of 8 total harbor porpoise were recorded 
within 60 km of Nome, four each during July and August 2016 (Blees et 
al. 2017). USACE detected one harbor porpoise during its 2019 and 2021 
monitoring.
    Clarke et al. (2019) indicated a maximum group size of four harbor 
porpoise in the Distribution and Relative Abundance of Marine Mammals 
in the Eastern Chukchi and Western Beaufort Seas, 2018 Annual Report 
(Clarke et al. 2019). NMFS estimates that one group of four harbor 
porpoise may enter the project area every other week during the 
construction period. Therefore, given the limited information in the 
project area to otherwise inform a take estimate, NMFS conservatively 
proposes to authorize 24 takes by Level B harassment of harbor porpoise 
(1 groups of 4 animals x 6 weeks).
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities, and it did 
not request take by Level A harassment of harbor porpoise. For some 
activities (i.e., impact driving of fender piles), the shutdown zones 
extends farther than Protected Species Observers (PSO) may be able to 
reliably detect harbor porpoise. However, given the portion of the zone 
within which PSOs could reliably detect a harbor porpoise, the 
infrequency of harbor porpoise observations during USACE's 2019 and 
2021 monitoring, and harbor porpoise sensitivity to noise, NMFS does 
not anticipate take by Level A harassment of harbor porpoise, nor is 
NMFS is proposing to authorize any.
Beluga Whale
    Beluga whales use Norton Sound during the entire open-water season, 
generally moving to southern Bering Sea waters during winter due to 
high ice concentrations in Norton Sound. During the spring and summer, 
beluga whales tend to concentrate in the eastern half of the Sound 
(Oceana and Kawerak 2014), but the whales may be seen migrating in 
large numbers close to the shoreline near Nome in late autumn (ADFG 
2012). Jewett (1997) stated beluga whales ``appear nearshore with the 
onset of herring spawning in early summer and feed on these as well as 
a wide variety of other fish congregating or migrating nearshore.'' 
They are often seen passing very close to the end of the Nome causeway 
during the fall migration and have been occasionally spotted within the 
Nome Outer Basin (USACE personal communication with Charlie Lean, 
2019). Large groups of beluga have been observed in fall in front of 
Cape Nome and near Topkok (Oceana and Kawerak 2014). In 2012, two 
beluga whales from the Eastern Bering Sea stock were tagged near Nome. 
Prior to being tagged both were known to range throughout Norton Sound. 
The first of the two tagged belugas left Norton Sound in early November 
and the second departed in mid-November (Citta et al. 2017). No beluga 
whales were seen during monitoring efforts at Nome during the 2016 
Quintillion subsea fiber optic cable project (Blees et al. 2017).
    USACE detected 129 beluga whales (n = 75 during September 2019, n = 
45 during September 2021, and n = 12 during October 2021) over 154 
hours of monitoring on 19 days in 2019 and 2021, making beluga whales 
the most frequently detected species during that monitoring period. 
Assuming that USACE would conduct a 12-hour work day on average, the 
pre-activity monitoring suggests a detection rate of approximately 10 
beluga whales per day.
    NMFS conservatively estimates that 15 beluga whales may enter the 
project area per day throughout the construction period. While 15 is 
higher than the detection rate reported from USACE's 2019 and 2021 
monitoring, the monitoring was conducted by one or two PSOs, and 
therefore, only a fraction of the area that would comprise the Level B 
harassment zones for this project was observed. Therefore, NMFS 
conservatively proposes to authorize 1,275 takes by Level B harassment 
of beluga whale (15 animals x 85 days).
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
implementation of the proposed shutdown zones is expected to eliminate 
the potential for take by Level A harassment of beluga whale. 
Therefore, USACE did not request take by Level A harassment of beluga 
whale, nor is NMFS is proposing to authorize any.
Steller Sea Lion
    USACE did not observe any Steller sea lions during the 2019 and 
2021 monitoring. Additional data regarding Steller sea lion occurrence 
in the Nome area is very limited. However, Steller sea lions are known 
to occur in the area, and observations suggest that Steller sea lions 
are becoming common in the northern Bering Sea, including Norton Sound. 
Sea lions have been detected hauling out in small numbers at Sledge 
Island, about 22 mi (35.4 km) west of Nome. Their change in range is 
perhaps attributed to climate-change-driven, northward movement of 
pelagic fish prey species, such as Pacific cod (USACE personal 
communication with Gay Sheffield, 2018). Further, during the 
Quintillion subsea fiber optic cable project in August 2016, a Steller 
sea lion was detected within 60 km of Nome (Blees et al. 2017).
    NMFS conservatively estimates that one Steller sea lion may enter 
the project area per day during the construction period. Therefore, 
given the limited information in the project area to otherwise inform a 
take estimate, NMFS conservatively proposes to authorize 85 takes by 
Level B harassment of Steller sea lion (1 animal x 85 days).

[[Page 27480]]

    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
especially in combination with the already low occurrence of Steller 
sea lion in the area, implementation of the proposed shutdown zones is 
expected to eliminate the potential for take by Level A harassment of 
Steller sea lion. Therefore, USACE did not request take by Level A 
harassment of Steller sea lion, nor is NMFS is proposing to authorize 
any.
Spotted Seal
    Most summer and fall concentrations of Norton Sound spotted seals 
are in the eastern portion of the Sound, where herring and small cod 
are more abundant. However, spotted seals are regularly seen at the 
Port of Nome and within the harbor area, especially before or after the 
busy summer season, sometimes hauled out on the beach or breakwater 
(USACE personal communication with Charlie Lean, 2019). Since the 
construction of the new entrance channel and east breakwater in 2006, 
the existing Outer Basin at the Port of Nome has become the new river 
mouth and a sort of artificial lagoon of the Snake River. Seals and 
other marine mammals tend to congregate there, especially in the autumn 
(Oceana and Kawerak 2014). During the Quintillion subsea fiber optic 
cable project, a total of 10 spotted seals were recorded within 60 km 
of Nome during July and August 2016 (Blees et al. 2017).
    USACE detected 23 spotted seals during its 2019 and 2021 
monitoring, making spotted seals the second most frequently detected 
species during that monitoring. Assuming that USACE would conduct a 12-
hour work day on average, the pre-activity monitoring suggests a 
detection rate of approximately two spotted seals per day.
    NMFS conservatively estimates that 20 spotted seals may enter the 
project area per day throughout the construction period. While 20 is 
higher than the detection rate reported from USACE's 2019 and 2021 
monitoring, the monitoring was conducted by one or two PSOs, and 
therefore, only a fraction of the area that would comprise the Level B 
harassment zones for this project was observed. Therefore, NMFS 
conservatively proposes to authorize 1,700 takes by Level B harassment 
of spotted seals (20 animals x 85 days).
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
implementation of the proposed shutdown zones is expected to eliminate 
the potential for take by Level A harassment of spotted seal. 
Therefore, USACE did not request take by Level A harassment of spotted 
seal, nor is NMFS is proposing to authorize any.
Ringed Seal
    Near Nome, ringed seals often occur in the open water offshore from 
Cape Nome and Safety Sound (Oceana and Kawerak 2014). Surveys conducted 
in the Bering Sea in the spring of 2012 and 2013 documented numerous 
ringed seals in both nearshore and offshore habitat extending south of 
Norton Sound (79 FR 73010, December 9, 2014; Muto et al. 2022). During 
the Quintillion subsea fiber optic cable project two ringed seals were 
recorded within 60 kilometers (km) of Nome during July 2016 (Blees et 
al. 2017). Braham et al. (1984) reported ringed seal densities ranging 
from 0.005 to 0.017 in the Bering Sea. Bengtson et al. (2005) reported 
ringed seal densities ranging from 1.62 to 1.91 in the Alaskan Chukchi 
Sea. Aerts et al. (2013) report combined ringed and spotted seal 
densities of 0.011 to 0.091 in the Northeastern Chukchi Sea. USACE did 
not detect ringed seals during its 2019 and 2021 monitoring.
    Neither USACE nor NMFS were able to locate more recent occurrence 
or density information for ringed seals in or near Norton Sound, beyond 
that described above. Therefore, USACE estimated the density of ringed 
seals in the project area to be 0.02 seals/km\2\, slightly higher than 
the dated, but most local, Braham et al. (1984) Bering Sea densities. 
Unable to locate more recent data for the area, NMFS concurs with this 
estimate.
    To calculate take by Level B harassment of ringed seal, USACE 
multiplied the estimated density (0.02 animals/km\2\) by the area of 
the Level B harassment zone for a given activity by the number of days 
that activity would occur (Table 8). NMFS concurs with this method and 
is conservatively proposing to authorize 92 takes by Level B harassment 
of ringed seal.

         Table 8--Area of Level B Harassment Zones and Number of Days on Which Each Activity Would Occur
----------------------------------------------------------------------------------------------------------------
                                                     Temporary
                                                  template piles   Anchor piles     Sheet piles    Fender piles
----------------------------------------------------------------------------------------------------------------
Number of Days of Activity......................          \a\ 24               2              57               2
Level B Harassment Zone (km\2\).................            8.41            2.96           50.46           751.9
----------------------------------------------------------------------------------------------------------------
\a\ Installation and removal.

    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
implementation of the proposed shutdown zones is expected to eliminate 
the potential for take by Level A harassment of ringed seal. Therefore, 
USACE did not request take by Level A harassment of ringed seal, nor is 
NMFS is proposing to authorize any.
Ribbon Seal
    Ribbon seals occur in the Bering Sea from late March to early May. 
From May to mid-July the ice recedes, and ribbon seals move further 
north into the Bering Strait and the southern part of the Chukchi Sea 
(Muto et al. 2022). An estimated 6,000-25,000 ribbon seals from the 
eastern Bering Sea occur in the Chukchi Sea during the spring open-
water period (Boveng et al. 2017). Braham et al. (1984) reported a 
maximum density of 0.002 seals/km\2\ from 1976 aerial surveys of ribbon 
seals in the Bering Sea. USACE did not detect ribbon seals during its 
2019 and 2021 monitoring.
    To calculate take by Level B harassment of ribbon seal, USACE 
multiplied the estimated density (0.002 animals/km\2\) by the area of 
the Level B harassment zone for a given activity by the number of days 
that activity would occur (Table 8). NMFS concurs with this method and 
is conservatively proposing to authorize 9 takes by Level B harassment 
of ribbon seal.
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
especially in combination with the already low occurrence of ribbon 
seals in the area, implementation of the proposed shutdown zones is 
expected to eliminate the potential for take by Level

[[Page 27481]]

A harassment of ribbon seal. Therefore, USACE did not request take by 
Level A harassment of ribbon seal, nor is NMFS is proposing to 
authorize any.
Bearded Seal
    Braham et al. (1984) reported bearded seal densities ranging from 
0.006 and 0.782 seals per km\2\ in the Bering Sea. Bengtson et al. 
(2005) reported bearded seal densities ranging from 0.07 to 0.14 seals/
km\2\ in the Alaskan Chukchi Sea. In the spring of 2012 and 2013, U.S. 
and Russian researchers conducted aerial abundance and distribution 
surveys over the entire ice-covered portions of the Bering Sea 
(Moreland et al. 2013). Conn et al. (2014), using a sub-sample of the 
data collected from the U.S. portion of the Bering Sea in 2012, 
calculated a posterior mean density estimate using an effective study 
area of 767,114 km\2\ of 0.39 bearded seals/km\2\ (95 percent CI 0.32-
0.47). Results from 2006 helicopter transect surveys over a 279,880 
km\2\ subset of the study area calculated density estimates of 0.22 
bearded seals/km\2\ (95 percent CI 0.12-0.61; Ver Hoef et al. 2013). 
USACE detected one bearded seal during its 2019 and 2021 monitoring.
    To calculate take by Level B harassment of bearded seal, USACE 
multiplied the estimated density (0.39 animals/km\2\) by the area of 
the Level B harassment zone for a given activity by the number of days 
that activity would occur (Table 8). NMFS concurs with this method and 
is proposing to conservatively authorize 2,554 takes by Level B 
harassment of bearded seal.
    USACE is planning to implement shutdown zones that extend to or 
exceed the Level A harassment isopleth for all activities. Therefore, 
implementation of the proposed shutdown zones is expected to eliminate 
the potential for take by Level A harassment of bearded seal. 
Therefore, USACE did not request take by Level A harassment of bearded 
seal, nor is NMFS is proposing to authorize any.

                   Table 9--Proposed Take and Proposed Take as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
                                                                                                   Proposed take
                                                                   Proposed take                       as a
                Species                           Stock              (Level B          Stock       percentage of
                                                                    harassment       abundance         stock
                                                                       only)                         abundance
----------------------------------------------------------------------------------------------------------------
Bearded Seal..........................  Beringia................           2,554             N/A             N/A
Ribbon Seal...........................  Unidentified............               9         184,697              <1
Ringed Seal...........................  Arctic..................              92             N/A             N/A
Spotted Seal..........................  Bering..................           1,700         461,625              <1
Steller sea lion......................  Western.................              85      \b\ 52,932              <1
Beluga whale..........................  Eastern Bering Sea......           1,275          12,269              10
Harbor Porpoise.......................  Bering Sea..............              24             N/A             N/A
Killer Whale..........................  Eastern North Pacific                 30       \a\ 1,920               2
                                         Alaska Resident.
                                        Eastern North Pacific                            \a\ 587               5
                                         Gulf of Alaska,
                                         Aleutian Islands and
                                         Bering Sea Transient.
Minke Whale...........................  Alaska..................              12             N/A             N/A
Gray Whale............................  Eastern North Pacific...              12          26,960              <1
----------------------------------------------------------------------------------------------------------------
N/A = Not applicable.
\a\ Nest is based upon counts of individuals identified from photo-ID catalogs.
\b\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys.

Effects of Specified Activities on Subsistence Uses of Marine Mammals

    The availability of the affected marine mammal stocks or species 
for subsistence uses may be impacted by this activity. The subsistence 
uses that may be affected and the potential impacts of the activity on 
those uses are described below. Measures included in this IHA to reduce 
the impacts of the activity on subsistence uses are described in the 
Proposed Mitigation section. Last, the information from this section 
and the Proposed Mitigation section is analyzed to determine whether 
the necessary findings may be made in the Unmitigable Adverse Impact 
Analysis and Determination section.
    During open-water months (May through October) species in the area 
harvested for subsistence uses include beluga whale, ice seals (ringed 
seal, bearded seal, ribbon seal, and spotted seal), and Steller sea 
lion.
    Eastern Bering Sea belugas are an important nutritional and 
cultural resource to Alaska Natives and are harvested by more than 20 
communities in Norton Sound and the Yukon (Ferguson et al. 2018b). The 
Eastern Bering Sea stock of beluga whales are harvested by nine Norton 
Sound communities (Elim, Golovin, Koyuk, Nome/Council, Saint Michael, 
Shaktoolik, Stebbins, Unalakleet, and White Mountain; NSB 2022). Frost 
and Suydam (2010) reported that of the nine communities, the highest 
annual harvest is at Koyuk (n=55) and an annual average of 0.6 belugas 
are harvested by Nome. Nome hunters harvest beluga on the west side of 
Cape Nome, all the way from Cape Nome to Nome, and from Nome west to 
Sledge Island (Oceana and Kawerak 2014). Beluga subsistence areas 
between spring and fall are documented between Cape Nome to Cape Darby 
and around the east coastline of Norton Sound to Stewart Island (Oceana 
and Kawerak 2014). Beluga whales have been traditionally hunted in 
Norton Sound; however, project impacts are not expected to reach 
traditional harvest areas.
    Ice seals are also hunted within the Norton Sound region. Georgette 
et al. (1998) summarizes a subsistence survey of six Norton Sound-
Bering Strait communities (Mainland coastal: Brevig Mission, Golovin, 
Shaktoolik, and Stebbins; Offshore: Savoonga and Gambell) between 1996 
and 1997 and reports seals taken for subsistence in all months, with 
seasonal peaks in spring (May-June) and fall (September-October). 
Bearded seals, preferred for their large size and quality of meat, were 
harvested by all communities, but Gambell had the highest harvest rate 
of any community. Bearded seals are typically harvested in early summer 
as they migrate northward. Spotted seals, valued for their skins, are 
reported in large numbers during ice-free months (Georgette et al. 
1998). Spotted seals occur closer to shore, allowing for easier 
harvesting than bearded seals or walrus, which occur further from shore 
and for a shorter window as they migrate north

[[Page 27482]]

more quickly (Oceana and Kawerak 2014). Ringed seals, the most abundant 
and accessible, were harvested in all months and taken in higher 
numbers than other species from the mainland coastal communities. 
Ribbon seals are harvested less often than other seals because their 
distribution does not overlap with most hunting areas and their taste 
is not preferred (Oceana and Kawerak 2014).
    Steller sea lions are rarely harvested in Norton Sound. During the 
1996-1997 survey, no Steller sea lion harvest was reported, however, 
hunters in Gambell, Savoonga, and Brevig Mission reported they do hunt 
for them occasionally (Georgette et al. 1998). Additionally, only 20 
Steller sea lions were reported taken between 1992 and 1998 (NMFS 2008; 
Wolf and Mishler 1999; Wolf and Hutchinson-Scarbrough 1999).
    Project activities mostly avoid traditional ice seal harvest 
windows (noted above) and are generally not expected to negatively 
impact hunting of seals. However, as noted above, some seal hunting 
does occur throughout the project period. The project could deter 
target species and their prey from the project area, increasing effort 
required for a successful hunt in that area. Construction may also 
disturb beluga whales, potentially causing them to avoid the project 
area and reducing their availability to subsistence hunters as well. 
Additionally, once the project is complete, the increased length and 
infrastructure at the Port of Nome could impact hunters' ability to 
access subsistence areas by increasing the time and fuel needed to exit 
the harbor, and increased vessel traffic at the Port following 
construction may introduce larger obstacles for subsistence vessels to 
maneuver and may affect marine mammals and their movements.

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)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat, as 
well as subsistence uses. This considers the nature of the potential 
adverse impact being mitigated (likelihood, scope, range). It further 
considers the likelihood that the measure will be effective if 
implemented (probability of accomplishing the mitigating result if 
implemented as planned), the likelihood of effective implementation 
(probability implemented as planned), and;
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, and impact on 
operations.

Mitigation for Marine Mammals and Their Habitat

    Shutdown Zones--The purpose of a shutdown zone is generally to 
define an area within which shutdown of the activity would occur upon 
sighting of a marine mammal (or in anticipation of an animal entering 
the defined area). Construction supervisors and crews, PSOs, and 
relevant USACE staff must avoid direct physical interaction with marine 
mammals during construction activity. If a marine mammal comes within 
10 meters of such activity, operations must cease and vessels must 
reduce speed to the minimum level required to maintain steerage and 
safe working conditions, as necessary to avoid direct physical 
interaction. Further, USACE must implement activity-specific shutdown 
zones as described in Table 10.

                                        Table 10--Required Shutdown Zones
----------------------------------------------------------------------------------------------------------------
                                                                                         Shutdown zone (m)
                   Pile type                           Pile driving method       -------------------------------
                                                                                     Cetaceans       Pinnipeds
----------------------------------------------------------------------------------------------------------------
Temporary template piles (Pipe piles <=24'')..  Vibratory.......................              10              10
                                                Impact..........................             300             150
(Alternate) Temporary template piles (H-piles   Vibratory.......................              10              10
 14'').
                                                Impact..........................             300             150
Anchor piles (14'' HP14x89 or similar)........  Vibratory.......................              10              10
                                                Impact..........................             300             150
Sheet piles (20'' PS31 or similar)............  Vibratory.......................              30              30
                                                Impact..........................             300             150
Fender piles (Pipe piles 36'')................  Vibratory.......................              70              30
                                                Impact..........................             500             210
Dredging \a\..................................  ................................             300             300
----------------------------------------------------------------------------------------------------------------
\a\ As noted previous, take of marine mammals is not anticipated to occur due to dredging. However, USACE will
  implement a shutdown zone of 300 m for all marine mammals during dredging.

    Protected Species Observers--The placement of PSOs during all 
construction activities (described in the Proposed Monitoring and 
Reporting section) would ensure that the entire shutdown zone is 
visible. USACE would employ three PSOs for vibratory driving of 
temporary template pipe piles, sheet piles, and fender pipe piles. For 
all other activities, USACE would employ one PSO.
    Pre and Post-Activity Monitoring--Monitoring must take place from 
30 minutes prior to initiation of pile driving activity (i.e., pre-
start clearance monitoring) through 30 minutes post-completion of pile 
driving activity. Pre-start clearance monitoring must be conducted 
during periods of visibility sufficient for the lead PSO to determine 
that the shutdown zones indicated in Table 10 are clear of marine 
mammals.

[[Page 27483]]

Pile driving may commence following 30 minutes of observation when the 
determination is made that the shutdown zones are clear of marine 
mammals. If a marine mammal is observed entering or within the shutdown 
zones, pile driving activity must be delayed or halted. If pile driving 
is delayed or halted due to the presence of a marine mammal, the 
activity may not commence or resume until either the animal has 
voluntarily exited and been visually confirmed beyond the shutdown zone 
or 15 minutes have passed without re-detection of the animal. If a 
marine mammal for which take by Level B harassment is authorized is 
present in the Level B harassment zone, activities would begin and 
Level B harassment take would be recorded.
    Monitoring for Level B Harassment--PSOs would monitor the shutdown 
zones and beyond to the extent that PSOs can see. Monitoring beyond the 
shutdown zones enables observers to be aware of and communicate the 
presence of marine mammals in the project areas outside the shutdown 
zones and thus prepare for a potential cessation of activity should the 
animal enter the shutdown zone.
    Soft Start--Soft-start procedures are used to provide additional 
protection to marine mammals by providing warning and/or giving marine 
mammals a chance to leave the area prior to the hammer operating at 
full capacity. For impact pile driving, soft start requires contractors 
to provide an initial set of three strikes at reduced energy, followed 
by a 30-second waiting period, then two subsequent reduced-energy 
strike sets. A soft start must be implemented at the start of each 
day's impact pile driving and at any time following cessation of impact 
pile driving for a period of 30 minutes or longer.

Mitigation for Subsistence Uses of Marine Mammals or Plan of 
Cooperation

    Regulations at 50 CFR 216.104(a)(12) further require IHA applicants 
conducting activities in or near a traditional Arctic subsistence 
hunting area and/or that may affect the availability of a species or 
stock of marine mammals for Arctic subsistence uses to provide a Plan 
of Cooperation or information that identifies what measures have been 
taken and/or will be taken to minimize adverse effects on the 
availability of marine mammals for subsistence purposes. A plan must 
include the following:
     A statement that the applicant has notified and provided 
the affected subsistence community with a draft plan of cooperation;
     A schedule for meeting with the affected subsistence 
communities to discuss proposed activities and to resolve potential 
conflicts regarding any aspects of either the operation or the plan of 
cooperation;
     A description of what measures the applicant has taken 
and/or will take to ensure that proposed activities will not interfere 
with subsistence whaling or sealing; and
     What plans the applicant has to continue to meet with the 
affected communities, both prior to and while conducting the activity, 
to resolve conflicts and to notify the communities of any changes in 
the operation.
    USACE provided a draft Plan of Cooperation (POC) to affected 
parties in October 2022. It includes a description of the project, 
community outreach that has already been conducted, and project 
mitigation measures for subsistence uses of marine mammals. USACE will 
continue to meet with the potentially affected communities and 
subsistence groups to discuss the project, its potential effects on 
subsistence, and proposed mitigation measures. Prior to the start of 
construction, USACE will provide notice to the communities of upcoming 
construction and timing updates using local radio stations, posted 
flyers, or other appropriate methods to ensure communities are aware of 
the construction activities. During construction, USACE will host a 
weekly call with subsistence leaders, construction leads, and the 
monitoring team lead(s) to discuss the items listed below, and it will 
distribute a one-page flyer via email to subsistence groups and 
construction teams.
     Planned construction activities occurring that day;
     Anticipated construction activities over the next day/
days;
     Any reported subsistence activities to be aware of (e.g., 
planned seal hunting and locations);
     Any other notable or pertinent project of subsistence 
information; and
     Project contact information (phone/email) for real-time 
communication.
    USACE will monitor this information consistently during the 
construction season and maintain communication with subsistence leaders 
to employ adaptive measures to mitigate any conflict with subsistence 
activities.
    The POC is a live document and will be updated throughout the 
project review and permitting process.
    In addition to the coordination described above to avoid or 
mitigate impacts to subsistence harvests of beluga whale and Steller 
sea lion, much of the project season avoids traditional ice seal 
harvest windows, which would be expected to avoid impacts to hunting of 
ice seals during much of the project season. USACE will coordinate with 
local communities and subsistence groups throughout construction to 
avoid or mitigate impacts to ice seal harvests.
    Based on our evaluation of USACE's proposed measures, as well as 
other measures considered by NMFS, 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, and on the availability of 
such species or stock for subsistence uses.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     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

[[Page 27484]]

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.

Visual Monitoring

    Marine mammal monitoring must be conducted in accordance with the 
Marine Mammal Monitoring Plan, dated February 2023. Marine mammal 
monitoring during pile driving and removal must be conducted by NMFS-
approved PSOs in a manner consistent with the following:
     PSOs must be independent of the activity contractor (for 
example, employed by a subcontractor) and have no other assigned tasks 
during monitoring periods;
     At least one PSO must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization;
     Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field) or training 
for experience performing the duties of a PSO during construction 
activities pursuant to a NMFS-issued incidental take authorization. 
PSOs may also substitute Alaska native traditional knowledge for 
experience. (NMFS recognizes that PSOs with traditional knowledge may 
also have prior experience, and therefore be eligible to serve as the 
lead PSO.);
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator must be designated. The lead 
observer must have prior experience performing the duties of a PSO 
during construction activity pursuant to a NMFS-issued incidental take 
authorization; and
     PSOs must be approved by NMFS prior to beginning any 
activity subject to this IHA.
    PSOs must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times, and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    USACE would employ three PSOs for vibratory driving of temporary 
template pipe piles, sheet piles, and fender pipe piles. For all other 
activities, USACE would employ one PSO. One PSO will be have an 
unobstructed view of all water within the shutdown zone and will be 
stationed at or near the project activity. Remaining PSOs, when 
applicable, will observe as much of the Level B harassment zone as 
possible. The second and third PSOs, when applicable, will monitor from 
the shoreline approximately 3.5 km to the east and west of the Port of 
Nome. While the exact monitoring stations have not yet been determined, 
USACE provided potential locations in Figure A-1 (Appendix A) of its 
Marine Mammal Monitoring and Mitigation Plan.
    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after all in water construction activities. In addition, PSOs 
would record all incidents of marine mammal occurrence, regardless of 
distance from activity, and would document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving 
activities include the time to install or remove a single pile or 
series of piles, as long as the time elapsed between uses of the pile 
driving equipment is no more than 30 minutes.

Reporting

    USACE would submit a draft report to NMFS within 90 calendar days 
of the completion of monitoring or 60 calendar days prior to the 
requested issuance of any subsequent IHA for construction activity at 
the same location, whichever comes first. The marine mammal monitoring 
report would include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report would include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including: (1) The number and type of piles that 
were driven and the method (e.g., impact, vibratory, down-the-hole); 
and (2) Total duration of driving time for each pile (vibratory 
driving) and number of strikes for each pile (impact driving).
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: (1) Name of PSO who sighted the animal(s) and PSO location 
and activity at time of sighting; (2) Time of sighting; (3) 
Identification of the animal(s) (e.g., genus/species, lowest possible 
taxonomic level, or unidentified), PSO confidence in identification, 
and the composition of the group if there is a mix of species; (4) 
Distance and location of each observed marine mammal relative to the 
pile being driven for each sighting; (5) Estimated number of animals 
(min/max/best estimate); (6) Estimated number of animals by cohort 
(adults, juveniles, neonates, group composition, etc.); (7) Animal's 
closest point of approach and estimated time spent within the 
harassment zone; (8) Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);
     Number of marine mammals detected within the harassment 
zones, by species; and
     Detailed information about implementation of any 
mitigation (e.g., shutdowns and delays), a description of specific 
actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    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.
    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the

[[Page 27485]]

Holder must report the incident to the Office of Protected Resources 
(OPR), NMFS ([email protected] and [email protected]) 
and to the Alaska regional stranding network (877-925-7773) as soon as 
feasible. If the death or injury was clearly caused by the specified 
activity, the Holder must immediately cease the activities until NMFS 
OPR is able to review the circumstances of the incident and determine 
what, if any, additional measures are appropriate to ensure compliance 
with the terms of this IHA. The Holder must not resume their activities 
until notified by NMFS.
    The report must include the following information:
    [ssquf] Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    [ssquf] Species identification (if known) or description of the 
animal(s) involved;
    [ssquf] Condition of the animal(s) (including carcass condition if 
the animal is dead);
    [ssquf] Observed behaviors of the animal(s), if alive;
    [ssquf] If available, photographs or video footage of the 
animal(s); and
    [ssquf] General circumstances under which the animal was 
discovered.

Monitoring Plan Peer Review

    The MMPA requires that monitoring plans be independently peer 
reviewed where the proposed activity may affect the availability of a 
species or stock for taking for subsistence uses (16 U.S.C. 
1371(a)(5)(D)(ii)(III)). Regarding this requirement, NMFS' implementing 
regulations state that upon receipt of a complete monitoring plan, and 
at its discretion, NMFS will either submit the plan to members of a 
peer review panel for review or within 60 days of receipt of the 
proposed monitoring plan, schedule a workshop to review the plan (50 
CFR 216.108(d)).
    NMFS established an independent peer review panel to review USACE's 
Monitoring Plan for the Port of Nome Modification Project. NMFS 
provided the panel with a copy of USACE's monitoring plan and provided 
them with a list of considerations to guide their discussion of the 
monitoring plan. The panel met in March 2023 and provided a final 
report to NMFS containing recommendations for USACE's monitoring plan 
on April 5, 2023. The Peer Review Panel's full report is posted on 
NMFS' website at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. NMFS 
is considering all of the recommendations made by the Peer Review panel 
and will incorporate appropriate changes in the monitoring requirements 
of the IHA, if issued. Additionally, NMFS will describe how the Peer 
Review Panel's findings and recommendations have been addressed in the 
Federal Register notice announcing the final IHA, if issued.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, the majority of our analysis applies to all 
the species listed in Table 9, given that many of the anticipated 
effects of this project on different marine mammal stocks are expected 
to be relatively similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, they are described independently in the analysis below.
    Pile driving and removal activities associated with the project, as 
outlined previously, have the potential to disturb or displace marine 
mammals. Specifically, the specified activities may result in take, in 
the form of Level B harassment, from underwater sounds generated from 
pile driving and removal. Potential takes could occur if individuals of 
these species are present in zones ensonified above the thresholds for 
Level B harassment, identified above, when these activities are 
underway.
    The takes by Level B harassment would be due to potential 
behavioral disturbance. No mortality or serious injury is anticipated 
given the nature of the activity, and no Level A harassment is 
anticipated due to USACE's construction method and planned mitigation 
measures (see Proposed Mitigation section).
    Effects on individuals that are taken by Level B harassment, on the 
basis of reports in the literature as well as monitoring from other 
similar activities, would likely be limited to reactions such as 
increased swimming speeds, increased surfacing time, or decreased 
foraging (if such activity were occurring; e.g., Thorson and Reyff 
2006; HDR, Inc. 2012; Lerma 2014; ABR 2016). Most likely, individuals 
would simply move away from the sound source and be temporarily 
displaced from the areas of pile driving and removal, although even 
this reaction has been observed primarily only in association with 
impact pile driving, which USACE does not plan to conduct expect in 
scenarios where it is required to successfully advance a pile. If sound 
produced by project activities is sufficiently disturbing, animals are 
likely to simply avoid the area while the activity is occurring, 
particularly as the project is expected to occur over just 85 in-water 
pile driving days.
    The project is also not expected to have significant adverse 
effects on affected marine mammals' habitats. The project activities 
would not modify existing marine mammal habitat for a significant 
amount of time. The activities may cause some fish to leave the area of 
disturbance, thus temporarily impacting marine mammals' foraging 
opportunities in a limited portion of the foraging range. We do not 
expect pile driving activities to have significant consequences to 
marine invertebrate populations. Given the short duration of the 
activities and the relatively small area of the habitat that may be 
affected, the impacts to marine mammal habitat, including fish and 
invertebrates, are not expected to cause significant or long-term 
negative consequences.

[[Page 27486]]

    The project area overlaps a BIA identified as important for feeding 
by Eastern Bering Sea belugas (Brower et al. 2023). The BIA that 
overlaps the project area is active May through November, which 
overlaps USACE's proposed work period (May to October). The BIA is 
considered to be of moderate importance, has moderately certain 
boundaries, and moderate data to support the identification of the BIA. 
The BIA was identified as having dynamic spatiotemporal variability. 
Regardless of the exact boundary of the BIA, the portion of the BIA 
that overlaps the project area would be extremely small in comparison 
to the full BIA. Further, the majority of the southeastern half of 
Norton Sound is separately identified as a ``child'' of the BIA that 
overlaps the project area. The child encompasses an especially high-
density area where belugas congregate to feed and is considered to be 
of higher importance than the parent BIA. The child BIA does not 
overlap the project area, indicating that animals in the Nome area 
would have available, high quality feeding habitat during the project 
period without necessarily being disturbed by the construction. 
Therefore, take of beluga whales using the parent BIA, given both the 
scope and nature of the anticipate impacts of pile driving exposure, is 
not anticipated to impact reproduction or survivorship of any 
individuals.
    The project area also overlaps ESA-designated critical habitat for 
both ringed seals and bearded seals. As described in the Description of 
Marine Mammals in the Area of Specified Activities section above, for 
both ringed seals and bearded seals, two of the three essential 
features identified for conservation of the species are related to sea 
ice. Given that USACE's project is anticipated to occur in the open 
water season, impacts from the project on sea ice habitat are not 
anticipated. The third essential feature for both ringed and bearded 
seals is primary prey sources to support the species. While the project 
activities could impact ringed seal and bearded seal foraging 
activities in critical habitat that overlaps the project area, the 
overlap between these areas is extremely small in comparison to the 
full ESA-designated critical habitat for each species, which includes 
most of the waters within the U.S. EEZ.
    As previously described, a UME has been declared for gray whales. 
However, we do not expect the takes proposed for authorization herein 
to exacerbate the ongoing UME. No injury, serious injury, or mortality 
of gray whales is expected or proposed for authorization, and take by 
Level B harassment is limited (14 takes over the duration of the 
authorization). As such, the proposed take by Level B harassment of 
gray whale would not exacerbate or compound upon the ongoing UME.
    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 injury, serious injury, or mortality is anticipated or 
authorized;
     The anticipated incidents of Level B harassment would 
consist of, at worst, temporary modifications in behavior that would 
not result in fitness impacts to individuals;
     The area impacted by the specified activity is very small 
relative to the overall habitat ranges of all species;
     While impacts would occur within areas that are important 
for feeding for multiple stocks, because of the small footprint of the 
activity relative to the area of these important use areas, and the 
scope and nature of the anticipated impacts of pile driving exposure, 
we do not expect impacts to the reproduction or survival of any 
individuals.
    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.

Small Numbers

    As noted previously, only take of small numbers of marine mammals 
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The number of instances of take for each species or stock proposed 
to be taken as a result of this project is included in Table 9. Our 
analysis shows that less than one-third of the best available 
population abundance estimate of each stock could be taken by 
harassment. The number of animals proposed to be taken for all stocks 
would be considered small relative to the relevant stock's abundances 
even if each estimated taking occurred to a new individual, which is an 
unlikely scenario.
    A lack of an accepted stock abundance value for the Alaska stock of 
minke whale did not allow for the calculation of an expected percentage 
of the population that would be affected. The most relevant estimate of 
partial stock abundance is 1,233 minke whales in coastal waters of the 
Alaska Peninsula and Aleutian Islands (Zerbini et al. 2006). Given 12 
proposed takes by Level B harassment for the stock, comparison to the 
best estimate of stock abundance shows, at most, 1 percent of the stock 
would be expected to be impacted.
    For the Bering Sea stock of harbor porpoise, the most reliable 
abundance estimate is 5,713, a corrected estimate from a 2008 survey. 
However, this survey covered only a small portion of the stock's range, 
and therefore, is considered to be an underestimate for the entire 
stock (Muto et al. 2022). Given the proposed 24 takes by Level B 
harassment for the stock, comparison to the abundance estimate, which 
is only a portion of the Bering Sea Stock, shows that, at most, less 
than one percent of the stock would be expected to be impacted.
    For the Alaska stock of bearded seals, a lack of an accepted stock 
abundance value did not allow for the calculation of an expected 
percentage of the population that would be affected. As noted in the 
2021 Alaska SAR (Muto et al. 2022), an abundance estimate is currently 
only available for the portion of bearded seals in the Bering Sea (Conn 
et al. 2014). The current abundance estimate for the Bering Sea is 
301,836 bearded seals. Given the proposed 2,554 takes by Level B 
harassment for the stock, comparison to the Bering Sea estimate, which 
is only a portion of the Alaska Stock (also includes animals in the 
Chukchi and Beaufort Seas), shows that, at most, less than one percent 
of the stock would be expected to be impacted.
    The Alaska stock of ringed seals also lack an accepted stock 
abundance value, and therefore, we were not able to calculate an 
expected percentage of the population that may be affected by USACE's 
project. As noted in the 2021 Alaska SAR (Muto et al. 2022), the

[[Page 27487]]

abundance estimate available, 171,418 animals, is only a partial 
estimate of the Bering Sea portion of the population (Conn et al. 
2014). As noted in the SAR, this estimate does not include animals in 
the shorefast ice zone, and the authors did not account for 
availability bias. Muto et al. (2022) expect that the Bering Sea 
portion of the population is actually much higher. Given the proposed 
92 takes by Level B harassment for the stock, comparison to the Bering 
Sea partial estimate, which is only a portion of the Alaska Stock (also 
includes animals in the Chukchi and Beaufort Seas), shows that, at 
most, less than one percent of the stock would be expected to be 
impacted.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected 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.
    Project impacts are generally not expected to reach traditional 
beluga harvest areas, and much of the project season avoids traditional 
ice seal harvest windows. While some hunting continues throughout the 
summer, we do not anticipate that there would be impacts to seals that 
would make them unavailable for subsistence hunters. Further, USACE 
will coordinate with local communities and subsistence groups 
throughout construction and avoid or mitigate impacts to marine mammal 
harvests by adaptively managing the project.
    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 USACE's 
proposed activities.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 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 OPR consults internally whenever we propose to authorize take for 
endangered or threatened species, in this case with the Alaska Regional 
Office.
    NMFS is proposing to authorize take of Western DPS Steller sea 
lion, ringed seal (Arctic subspecies), and bearded seal (Beringia DPS), 
which are listed under the ESA. The Permits and Conservation Division 
has requested initiation of section 7 consultation with the Alaska 
Regional Office for the issuance of this IHA. NMFS 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 USACE for conducting the Port of Nome Modification 
Project in Nome, Alaska, during the open water season in 2024, 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-construction-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 
construction project. We also request comment on the potential renewal 
of this proposed IHA as described in the paragraph below. Please 
include with your comments any supporting data or literature citations 
to help inform decisions on the request for this IHA or a subsequent 
renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, 1-year renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical or nearly 
identical activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond 1 year from expiration 
of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
    Upon review of the request for renewal, the status of the affected 
species or stocks, and any other pertinent information, NMFS determines 
that there are no more than minor changes in the activities, the 
mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: April 21, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-09041 Filed 5-1-23; 8:45 am]
BILLING CODE 3510-22-P