[Federal Register Volume 88, Number 177 (Thursday, September 14, 2023)]
[Notices]
[Pages 63067-63084]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-19903]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD199]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Ferry Berth Construction in Tongass 
Narrows in Ketchikan, Alaska

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

ACTION: Notice; Issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
the Alaska Department of Transportation and Public Facilities (ADOT&PF) 
to incidentally harass marine mammals during construction activities 
associated with ferry berth construction in Tongass Narrows in 
Ketchikan, Alaska.

DATES: This authorization is effective from September 11, 2023 to 
September 10, 2024.

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

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

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed IHA is provided to the public for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

Summary of Request

    On January 24, 2023, NMFS received a request from ADOT&PF for an 
IHA to take marine mammals incidental to the construction of and 
improvements to four (initially five--see explanation below) ferry 
berths in Tongass Narrows in Ketchikan, Alaska. On February 23, 2023, 
ADOT&PF submitted a memo proposing additional construction activities 
at this project site, which was later retracted on March 21, 2023. 
Following NMFS' review of the application and discussions between NMFS 
and ADOT&PF, on May 2, 2023, ADOT&PF asked NMFS to halt processing of 
the IHA until it submitted an acoustic monitoring report associated 
with previous work at the project site. ADOT&PF submitted the report on 
May 24, 2023. NMFS reviewed and accepted the results in the report, and 
the application was deemed adequate and complete on June 27, 2023. 
ADOT&PF's request is for take of 11 species of marine mammals, by Level 
B harassment and, for Steller sea lion (Eumetopias jubatus), harbor 
seal (Phoca vitulina), northern elephant seal (Mirounga 
angustirostris), harbor porpoise (Phocoena phocoena), and Dall's 
porpoise (Phocoenoides dalli), Level A harassment. Neither ADOT&PF nor 
NMFS expect serious injury or mortality to result from this activity 
and, therefore, an IHA is appropriate.
    NMFS previously issued two consecutive IHAs to ADOT&PF for this 
work (85 FR 673, January 7, 2020), which covered construction at the 
following six sites: Revilla New Ferry Berth and Upland Improvements 
(Revilla New Berth), New Gravina Island Shuttle Ferry Berth/Related 
Terminal Improvements (Gravina New Berth), Gravina Airport Ferry Layup 
Facility, Gravina Freight Facility, Revilla Refurbish Existing Ferry 
Berth Facility, and Gravina Refurbish Existing Ferry Berth Facility 
(Figure 1). Due to various project delays (and two minor changes to the 
phase 1 IHA activities), the phase 1 IHA was renewed (86 FR 23938, May 
05, 2021) and the phase 2 IHA was reissued (87 FR 12117, March 3, 
2022). Upon the expiration of the phase 1 renewal, because a subset of 
work had still not been completed, ADOT&PF requested, and NMFS issued, 
a new IHA (87 FR 15387, March 18, 2022) which was renewed upon its 
expiration (88 FR 13802, March 6, 2023). The reissued phase 2 IHA 
expired on February 28, 2023. While the current renewal IHA (88 FR 
13802, March 6, 2023) does not expire until March 5, 2024, ADOT&PF 
proposed new project components that warrant a new IHA, and a subset of 
activities covered under the reissued phase 2 IHA remain incomplete. As 
such, ADOT&PF requested a new IHA to authorize take of marine mammals 
associated with all remaining work at the Tongass Narrows sites. Work 
at the Gravina Airport Ferry Layup Facility was completed prior to the 
application for this new IHA. Since the submission of ADOT&PF's 2023 
IHA

[[Page 63068]]

application, work has also been completed at the Gravina Freight 
Facility. As such, remaining work planned is limited to four project 
sites: Revilla New Berth, Gravina New Berth, Revilla Refurbish Existing 
Ferry Berth Facility, and Gravina Refurbish Existing Ferry Berth 
Facility. ADOT&PF has complied with all the requirements (e.g., 
mitigation, monitoring, and reporting) of the previous IHAs with the 
exception of one incident in which ADOT&PF reported that a pile had 
been removed without the presence of a Protected Species Observer (PSO) 
on site. ADOT&PF reported the incident immediately and retrained the 
Construction Contractor's Foreman and ADOT&PF's on-site representative. 
ADOT&PF also notified NMFS on May 18, 2023 that 12 20'' piles that were 
not included in the renewal, but were included in the initial IHA on 
which the renewal was based, were driven after expiration of the 
initial IHA (while the renewal was effective).
    Monitoring results from the previous IHAs are discussed in the 
Potential Effects of Specified Activities on Marine Mammals and their 
Habitat and the Estimated Take of Marine Mammals section.

Description of Specified Activity

    ADOT&PF is making improvements to two existing ferry berths and 
constructing two new ferry berths on Gravina Island and Revillagigedo 
(Revilla) Island in Tongass Narrows, near Ketchikan, in southeast 
Alaska (see Figure 1 of the notice of proposed IHA (88 FR 46746; July 
20, 2023). The existing ferry facilities improve access to developable 
land on Gravina Island, improve access to the Ketchikan International 
Airport, and facilitate economic development in the Ketchikan Gateway 
Borough. The new ferry berths provide redundancy to the existing ferry 
berths. The project's planned activities that have the potential to 
take marine mammals, by Level A harassment and Level B harassment, 
include down-the-hole (DTH) drilling of rock sockets and tension 
anchors, vibratory installation and removal of temporary steel pipe 
piles and/or H-piles, vibratory and impact installation of permanent 
steel pipe piles, and vibratory removal of permanent piles (in cases 
where work is being redone). The marine construction associated with 
the planned activities is expected to occur over 131 non-consecutive 
days over 1 year.
    A detailed description of the planned construction project is 
provided in the Federal Register notice for the proposed IHA (88 FR 
46746, July 20, 2023). Since that time, no changes have been made to 
planned activities. Therefore, a detailed description is not provided 
here. Please refer to that Federal Register notice for the description 
of the specified activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to ADOT&PF was published 
in the Federal Register on July 20, 2023 (88 FR 46746). That notice 
described, in detail, ADOT&PF's activities, the marine mammal species 
that may be affected by the activities, and the anticipated effects on 
marine mammals. In that notice, we requested public input on the 
request for authorization described therein, our analyses, the proposed 
authorization, and any other aspect of the notice of proposed IHA, and 
requested that interested persons submit relevant information, 
suggestions, and comments. During the 30-day public comment period, 
NMFS did not receive any public comments.

Changes From the Proposed IHA to Final IHA

    Since the Federal Register notice of the proposed IHA was published 
(88 FR 46746, July 20, 2023), NMFS published the final 2022 Alaska and 
Pacific Stock Assessment Reports (SARs), which describe revised stock 
structures under the MMPA for humpback whales and southeast Alaska 
harbor porpoise (Carretta et al., 2023; Young et al., 2023). In the 
notice of proposed IHA, we explained that although we typically 
consider updated peer-reviewed data provided in draft SARs to be the 
best available science, and use the information accordingly, we make 
exception for proposed revised stock structures. Upon finalization of 
these revised stock structures, we have made appropriate updates, 
including descriptions of the potentially affected stocks (see Table 
1), attribution of take numbers to stock (see Estimated Take of Marine 
Mammals), and by updating our analyses to ensure the necessary 
determinations are made for the new stocks (see Negligible Impact 
Analysis and Determination and Small Numbers).
    Additionally, as requested by ADOT&PF, NMFS made two changes to the 
PSO requirements since publication of the proposed IHA. First, NMFS 
revised the requirement for PSOs to be independent of the activity 
contractor (for example, employed by a subcontractor), to reflect that 
PSOs must be independent (not be part of the construction crew) but not 
necessarily employed by a subcontractor. This change is intended to 
align this requirement with that in the active IHA to allow PSOs who 
are currently working on the project to continue to do so. Second, NMFS 
proposed to require ADOT&PF to employ three PSOs for DTH activities. 
After publication of the proposed IHA, ADOT&PF requested for NMFS to 
revise this measure to require two PSOs for DTH activities, given that 
the zone sizes for DTH activities, like those of impact pile driving, 
are small enough to be adequately monitored by two PSOs. NMFS 
concurred, and therefore, the final IHA requires ADOT&PF to employ at 
least two PSOs for DTH activities, rather than three.
    Finally, NMFS corrected a typographical error in Table 8 of the 
notice of the proposed IHA (88 FR 46746, July 20, 2023). The table 
omitted the Level B harassment isopleth for DTH of tension anchors, 
which should have been listed as 1,274 m. The corresponding table in 
the proposed IHA at the time of publishing was correct.

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, incorporated here by reference, instead of 
reprinting the information. Additional information regarding population 
trends and threats may be found in NMFS' SARs (https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS' 
website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species or stocks for which take is expected and 
authorized for this activity, and summarizes information related to the 
population or stock, including regulatory status under the MMPA and 
Endangered Species Act (ESA) and potential biological removal (PBR), 
where known. PBR is defined by the MMPA as the maximum number of 
animals, not including natural mortalities, that may be removed from a 
marine mammal stock while allowing that stock to reach or maintain its 
optimum sustainable population (as described in NMFS' SARs). While no 
serious injury or mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species or 
stocks and other threats.

[[Page 63069]]

    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 and Pacific Ocean SARs All values presented in Table 
1 are the most recent available at the time of publication (Caretta et 
al., 2023, Young et al., 2023) and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                     Table 1--Marine Mammal Species Likely Impacted by the Specified Activities \1\
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                                                                                      ESA/MMPA status;   Stock abundance (CV,
            Common name                  Scientific name              Stock           Strategic (Y/N)      Nmin, most recent        PBR      Annual M/SI
                                                                                            \2\          abundance survey) \3\                   \4\
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                                            Order Artiodactyla--Infraorder Cetacea--Mysticeti (baleen whales)
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Family Balaenopteridae (rorquals):
    Minke Whale \5\................  Balaenoptera            Alaska................  -,-,N              N/A (N/A, N/A, N/A)...          UND            0
                                      acutorostrata.
    Fin Whale \6\..................  Balaenoptera physalus.  Northeast Pacific.....  E, D, Y            3,168 (0.26, 2,554,             UND          0.6
                                                                                                         2013).
    Humpback Whale \7\.............  Megaptera novaeangliae  Hawai[revaps]i........  -,-,N              11,278 (0.56, 7,265,            127         19.6
                                                                                                         2020).
                                                             Mexico--North Pacific.  T, D, Y            N/A (N/A, N/A, 2006)..          UND         0.56
Family Eschrichtiidae:
    Gray whale.....................  Eschrichtius robustus.  Eastern North Pacific.  -,-,N              26,960 (0.05, 25,849,           801          131
                                                                                                         2016).
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                                                  Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
    Pacific White-sided Dolphin....  Lagenorhynchus          N Pacific.............  -,-,N              26,880 (N/A, N/A,               UND            0
                                      obliquidens.                                                       1990).
    Killer Whale...................  Orcinus orca..........  Eastern North Pacific   -,-,N              1,920, (N/A, 1,920,              19          1.3
                                                              Alaska Resident.                           2019).
                                                             Eastern North Pacific   -,-,N              302 (N/A, 302, 2018)..          2.2          0.2
                                                              Northern Resident.
                                                             West Coast Transient..  -,-,N              349 (N/A, 349, 2018)..          3.5          0.4
Family Phocoenidae (porpoises):
    Harbor Porpoise \8\............  Phocoena phocoena.....  Southern Southeast      -,-,Y              890 (0.37, 610, 2019).          6.1          7.4
                                                              Alaska Inland Waters.
    Dall's Porpoise \9\............  Phocoenoides dalli....  Alaska................  -,-,N              15,432 (0.097, 13,110,          131           37
                                                                                                         2021).
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                                                               Order Carnivora--Pinnipedia
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Family Otariidae (eared seals and
 sea lions):
    Steller Sea Lion...............  Eumetopias jubatus....  Eastern...............  -,-,N              43,201 (N/A, 43,201,          2,592          112
                                                                                                         2017).
Family Phocidae (earless seals):
    Northern Elephant Seal.........  Mirounga                CA Breeding...........  -,-,N              187,386 (N/A, 85,369,         5,122         13.7
                                      angustirostris.                                                    2013).
    Harbor Seal....................  Phoca vitulina........  Clarence Strait.......  -,-,N              27,659 (N/A, 24,854,            746           40
                                                                                                         2015).
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\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).
\2\ ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). 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-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\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\ No population estimates have been made for the number of minke whales in the entire North Pacific. Some information is available on the numbers of
  minke whales on some areas of Alaska, but in the 2009, 2013 and 2015 offshore surveys, so few minke whales were seen during the surveys that a
  population estimate for the species in this area could not be determined (Rone et al., 2017). Therefore, this information is N/A (not available).
\6\ The best available abundance estimate for this stock is not considered representative of the entire stock as surveys were limited to a small portion
  of the stock's range. Based upon this estimate and the Nmin, the PBR value is likely negatively biased for the entire stock.
\7\ Abundance estimates for the Mexico-North Pacific Stock of humpback whale are based upon data collected more than 8 years ago and therefore, current
  estimates are considered unknown.
\8\ Abundance estimates assumed that detection probability on the trackline was perfect; work is underway on a corrected estimate. Additionally,
  preliminary data results based on eDNA analysis show genetic differentiation between harbor porpoise in the northern and southern regions on the
  inland waters of southeast Alaska. Geographic delineation is not yet known. Data to evaluate population structure for harbor porpoise in Southeast
  Alaska have been collected and are currently being analyzed. Should the analysis identify different population structure than is currently reflected
  in the Alaska SARs, NMFS will consider how to best revise stock designations in the future.
\9\ Previous abundance estimates covering the entire stock's range are no longer considered reliable and the current estimates presented in the SARs and
  reported here only cover a portion of the stock's range. Therefore, the calculated Nmin and PBR is based on the 2015 survey of only a small portion of
  the stock's range. PBR is considered to be biased low since it is based on the whole stock whereas the estimate of mortality and serious injury is for
  the entire stock's range.

    As indicated above, all 11 species (with 13 managed stocks) in 
Table 1 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur.
    A detailed description of the species likely to be affected by 
ADOT&PF's project, including brief introductions to the species and 
relevant stocks as well as available information regarding populations 
trends and threats, and

[[Page 63070]]

information regarding local occurrence, were provided in the Federal 
Register notice for the proposed IHA (88 FR 46746, July 20, 2023).The 
2022 Alaska and Pacific SARs described a revised stock structure for 
humpback whales which modifies the previous stocks designated under the 
MMPA to align more closely with the ESA-designated DPSs (Caretta et 
al., 2023; Young et al., 2023). Specifically, the three previous North 
Pacific humpback whale stocks (Central and Western North Pacific stocks 
and a CA/OR/WA stock) were replaced by five stocks, largely 
corresponding with the ESA-designated DPSs. These include Western North 
Pacific and Hawaii stocks and a Central America/Southern Mexico-CA/OR/
WA stock (which corresponds with the Central America DPS). The 
remaining two stocks, corresponding with the Mexico DPS, are the 
Mainland Mexico-CA/OR/WA and Mexico-North Pacific stocks (Caretta et 
al., 2023; Young et al., 2023). The former stock is expected to occur 
along the west coast from California to southern British Columbia, 
while the latter stock may occur across the Pacific, from northern 
British Columbia through the Gulf of Alaska and Aleutian Islands/Bering 
Sea region to Russia.
    In the proposed IHA, NMFS stated that the Central North Pacific 
stock of humpback whale was likely to be impacted by ADOT&PF's 
activities. Given the revised stock structure, NMFS has reanalyzed the 
potential for take of each stock of humpback whale and determined that 
the Hawaii stock and the Mexico- North Pacific stock are likely to be 
impacted by ADOT&PF's activities.
    The 2022 Alaska SARs described a revised stock structure for 
southeast Alaska harbor porpoise, which were split from one stock into 
three: the Northern Southeast Alaska Inland Waters, Southern Southeast 
Alaska Inland Waters, and Yakutat/Southeast Alaska Offshore Waters 
harbor porpoise stocks (Young et al., 2023). This update better aligns 
harbor porpoise stock structure with genetics, trends in abundance, and 
information regarding discontinuous distribution trends (Young et al., 
2023). Harbor porpoises found in the Tongass Narrows area are assumed 
to be members of the Southern Southeast Alaska Inland Waters stock, 
based on the geographical range of the stock. Please refer to the 
notice of the proposed IHA (88 FR 46746, July 20, 2023) for species 
descriptions. Please also refer to the NMFS' website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts, 
and to the SARs (https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) for more information about 
the changes to humpback whale and harbor porpoise stock structures.

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 2.

                  Table 2--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

    The effects of underwater noise from ADOT&PF's construction 
activities have the potential to result in behavioral harassment of 
marine mammals in the vicinity of the project area. The notice of the 
proposed IHA (88 FR 46746, July 20, 2023) included a discussion of the 
effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from ADOT&PF's construction activities on 
marine mammals and their habitat. That information and analysis is 
incorporated by reference into these final IHA determinations and is 
not repeated here; please refer to the Federal Register notice of 
proposed IHA (88 FR 46746, July 20, 2023).

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
authorized through this IHA, which

[[Page 63071]]

informs 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 will primarily be by Level B harassment, as use of 
the acoustic sources (i.e., impact and vibratory pile driving and 
removal and DTH) has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result, primarily 
for high frequency cetaceans, phocids, and otariids because predicted 
auditory injury zones are larger than for other hearing groups. 
Auditory injury is unlikely to occur for other groups. The mitigation 
and monitoring measures are expected to minimize the severity of the 
taking to the extent practicable.
    As described previously, no serious injury or mortality is 
anticipated or authorized for this activity. Below we describe how the 
take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur 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, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., impact pile driving) or intermittent (e.g., 
scientific sonar) sources. This take estimation includes disruption of 
behavioral patterns resulting directly in response to noise exposure 
(e.g., avoidance), as well as the resulting indirectly form the 
associated impacts such as Temporary Threshold Shift (TTS) or masking. 
ADOT&PF's planned activity includes the use of continuous (vibratory 
pile driving/removal and DTH) and impulsive (impact pile driving and 
DTH) 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). ADOT&PF's 
planned activity includes the use of impulsive (impact pile driving and 
DTH) and non-impulsive (vibratory pile driving/removal and DTH) 
sources.
    These thresholds are provided in Table 3 below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                        PTS onset thresholds *  (received level)
             Hearing group             -------------------------------------------------------------------------
                                                Impulsive                          Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans..........  Cell 1: Lp,0-pk,flat: 219  Cell 2: LE,p,LF,24h: 199 dB.
                                         dB; LE,p,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans..........  Cell 3: Lp,0-pk,flat: 230  Cell 4: LE,p,MF,24h: 198 dB.
                                         dB; LE,p,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.........  Cell 5: Lp,0-pk,flat: 202  Cell 6: LE,p,HF,24h: 173 dB.
                                         dB; LE,p,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)....  Cell 7: Lp,0-pk.flat: 218  Cell 8: LE,p,PW,24h: 201 dB.
                                         dB; LE,p,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)...  Cell 9: Lp,0-pk,flat: 232  Cell 10: LE,p,OW,24h: 219 dB.
                                         dB; LE,p,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric 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 are recommended for consideration.

[[Page 63072]]

 
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
  exposure level (LE,p) has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to be
  more reflective of International Organization for Standardization standards (ISO 2017). The subscript ``flat''
  is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized
  hearing range of marine mammals (i.e., 7 Hz to 160 kHz). 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 weighted
  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 thresholds will be exceeded.

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 planned project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact pile driving, vibratory 
pile driving and removal, and DTH).
    The intensity of pile driving sounds is greatly influenced by 
factors such as the type of piles (material and diameter), hammer type, 
and the physical environment (e.g., sediment type) in which the 
activity takes place. The ADOT&PF evaluated SPL measurements available 
for certain pile types and sizes from similar activities elsewhere to 
determine appropriate proxy levels for their planned activities. The 
ADOT&PF also initially referred to preliminary results from a sound 
source verification study to determine SPLs for DTH of 8-inch tension 
anchors and Transmission Loss values (TLs) for all DTH activities. As 
discussed in the Summary of Request section above, a Sound Source 
Verification (SSV) report detailing sound source values and TL 
coefficients collected at the project site was subsequently submitted.
    To determine appropriate proxy SPLs for impact and vibratory pile 
driving of all pile types, NMFS completed a comprehensive review of 
source levels relevant to Southeast Alaska to generate regionally-
specific source levels. NMFS compiled all available data from Puget 
Sound and Southeast Alaska and adjusted the data to standardize 
distance from the measured pile to 10 meters (m). NMFS then calculated 
average source levels for each project and for each pile type. NMFS 
weighted impact pile driving project averages by the number of strikes 
per pile following the methodology in Navy (2015). The source levels 
for these various pile types, sizes and methods are listed in Table 4. 
Additionally, ADOT&PF requested, and NMFS agreed, to use the 24-inch 
sound source values for impact or vibratory pile driving of 14-inch H-
piles, because the source value of smaller piles of the same general 
type (steel) are not expected to exceed a larger pile.
    NMFS recommends treating DTH systems as both impulsive and 
continuous, non-impulsive sound source types simultaneously. Thus, 
impulsive thresholds are used to evaluate Level A harassment, and 
continuous thresholds are used to evaluate Level B harassment. NMFS 
(2022) recommended guidance on DTH systems (https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf) outlines its 
recommended source levels for DTH systems. NMFS has applied that 
guidance in this analysis (see Table 4 for NMFS' source levels). Note 
that the values in this table represent the SPL referenced to a 
distance of 10 m (33 (feet) ft) from the source.
    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; for practical spreading equals 15
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 Tongass Narrows are not available for 
vibratory pile installation and removal and impact pile driving; 
therefore, the default coefficient of 15 is used to determine the 
distances to the Level A harassment and Level B harassment thresholds 
for these activities and associated pile types. In the case of DTH 
activities, ADOT&PF conducted SSV at the project site for DTH of 24-
inch rock sockets and 8-inch tension anchors. NMFS reviewed the TL data 
from this monitoring and has incorporated the most conservative 
transmission loss values measured for each pile type at the project 
site in its analysis herein (Table 4).

Table 4--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, DTH,
                                           and Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
                                                                    Peak SPL (dB                          TL
                               RMS SPL (dB re    SELss (dB re 1         re 1          References     coefficient
                                1 [micro]Pa)   [micro]Pa \2\ sec)    [micro]Pa)      levels  (TL)        \1\
----------------------------------------------------------------------------------------------------------------
                                                Vibratory Hammer
----------------------------------------------------------------------------------------------------------------
30-inch steel piles..........             166                  NA              NA  NMFS Analysis--            15
                                                                                    C. Hotchkin
                                                                                    April 24, 2023.
24-inch steel piles..........             163                  NA              NA  NMFS Analysis--            15
                                                                                    C. Hotchkin
                                                                                    April 24, 2023.
Steel 14'' H-piles \2\.......             163                  NA              NA  24-inch as proxy           15
----------------------------------------------------------------------------------------------------------------
                               DTH of Rock Sockets and Tension Anchors--Continuous
----------------------------------------------------------------------------------------------------------------
24-inch (Rock Socket)........             167                  NA              NA  Heyvaert & Reyff         19.5
                                                                                    2021; (Reyff
                                                                                    and Ambaskar
                                                                                    2023).

[[Page 63073]]

 
8-inch DTH (Tension Anchor)..             156                  NA              NA  Reyff & Heyvaert         17.1
                                                                                    2019; Reyff
                                                                                    2020; (Reyff
                                                                                    and Ambaskar
                                                                                    2023).
----------------------------------------------------------------------------------------------------------------
                                                  Impact Hammer
----------------------------------------------------------------------------------------------------------------
30-inch steel piles..........             195                 183             210  NMFS Analysis--            15
                                                                                    C. Hotchkin
                                                                                    April 24, 2023.
24-inch steel piles..........             190                 177             203  Caltrans 2015,             15
                                                                                    Caltrans 2020.
Steel 14'' H-piles \2\.......             190                 177             203  24-inch as proxy           15
----------------------------------------------------------------------------------------------------------------
                               DTH of rock sockets and tension anchors--Impulsive
----------------------------------------------------------------------------------------------------------------
24-inch (Rock Socket)........              NA                 159             184  Heyvaert & Reyff         19.9
                                                                                    2021; (Reyff
                                                                                    and Ambaskar
                                                                                    2023).
8-inch (Tension anchor)......              NA                 144             170  Reyff 2020;              17.1
                                                                                    (Reyff and
                                                                                    Ambaskar 2023).
----------------------------------------------------------------------------------------------------------------
\1\ NMFS recommends a default transmission loss of 15 * log10(R) when site-specific data are not available
  (NMFS, 2020; NMFS, 2022).
\2\ For 14-inch H piles, NMFS uses sound source level data from 24-inch piles as a conservative proxy.
Note: all SPLs are unattenuated and represent the SPL referenced to a distance of 10 m from the source; NA = Not
  applicable; dB re 1 [micro]Pa = decibels (dB) referenced to a pressure of 1 microPascal, measures underwater
  SPL; dB re 1 [micro]Pa2-sec = dB referenced to a pressure of 1 microPascal squared per second, measures
  underwater Sound Exposure Level (SEL).

    All Level B harassment isopleths are reported in Table 5 below. Of 
note, based on the geography of Tongass Narrows and the surrounding 
islands, sound will not reach the full distance of the Level B 
harassment isopleth in most directions. Generally, due to interaction 
with land, only a thin slice of the possible area will be ensonified to 
the full distance of the Level B harassment isopleth.

     Table 5--Level B Harassment Isopleths by Activity and Pile Size
------------------------------------------------------------------------
                                   Pile diameter    Level B  harassment
            Activity                   (inch)          isopleth  (m)
------------------------------------------------------------------------
Vibratory Installation and                     30                 11,659
 Removal........................               24                  7,365
                                               14
DTH Rock Sockets................               24                  2,572
DTH Tension Anchor..............                8                  1,274
Impact Installation.............               30                  2,154
                                               24                  1,000
                                               14
------------------------------------------------------------------------

    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 or removal or DTH using any of 
the methods discussed above, 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 is expected to incur PTS. 
Inputs used in the optional User Spreadsheet tool, and the resulting 
estimated isopleths, are reported in Table 6 and Table 7.

                                                          Table 6--NMFS User Spreadsheet Inputs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Vibratory pile driving                            DTH                                   Impact
                                 -----------------------------------------------------------------------------------------------------------------------
                                     30-inch steel       24-inch steel     Rock socket  (24   Tension anchor  (8-    30-inch steel       24-inch steel
                                         piles         piles or steel H-         inch)               inch)               piles         piles or steel H-
                                 --------------------        pile        ------------------------------------------------------------        pile
                                                     --------------------                                                            -------------------
                                   Installation  or    Installation  or      Installation        Installation        Installation
                                        removal             removal                                                                      Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used............  A.1) Vibratory      A.1) Vibratory      E.2) DTH Pile       E.2) DTH Pile       E.1) Impact Pile    E.1) Impact Pile
                                   Pile Driving.       Pile Driving.       Driving.            Driving.            Driving.            Driving.
Source Level (SPL)..............  166 RMS...........  163 RMS...........  167 RMS, 159 SEL..  156 RMS, 144 SEL..  183 SEL...........  177 SEL.

[[Page 63074]]

 
Transmission Loss Coefficient...  15................  15................  19.5, 19.9........  17.1, 17.1........  15................  15.
Weighting Factor Adjustment       2.5...............  2.5...............  2.................  2.................  2.................  2.
 (kHz).
Activity Duration (hours) within  0.5-6 *...........  0.5-8 *...........  1-8...............  1-8...............
 24 hours.
Strike rate strike per second...  ..................  ..................  10................  19................
Number of strikes per pile......  ..................  ..................  ..................  ..................  50 (temporary);     50 (temporary);
                                                                                                                   200 (permanent).    200 (permanent).
Number of piles per day.........  1-6...............  1-8...............  1.................  1.................  1-3...............  1-3.
Distance of sound pressure level  10................  10................  10................  10................  10................  10.
 measurement.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* A range of activity durations (vibratory and DTH), strikes per pile (impact), piles per day are listed because ADOT&PF anticipates that they can
  install or remove piles of the same size at different rates at different sites. Duration estimates for DTH assume that multiple rock sockets and
  tension anchors will be installed each day, with a maximum daily duration of 8 hours.

    Level A harassment thresholds for impulsive sound sources (impact 
pile driving and DTH) are defined for both cumulative sound exposure 
level (SELcum) and Peak SPL with the threshold that results in the 
largest modeled isopleth for each marine mammal hearing group used to 
establish the Level A harassment isopleth. In this project, Level A 
harassment isopleths based on SELcum were always larger than those 
based on Peak SPL. It should be noted that there is a duration 
component when calculating the Level A harassment isopleth based on 
SELcum, and this duration depends on the number of piles that will be 
driven in a day and strikes per pile. For some activities, ADOT&PF 
plans to drive variable numbers of piles per day throughout the project 
(See ``Average Piles per Day (Range)'' in Table 1 of the Federal 
Register notice for the proposed IHA, (88 FR 46746, July 20, 2023)). 
NMFS accounted for this variability in its analysis. For each activity, 
ADOT&PF provided the minimum and maximum potential durations of the 
activity. In some cases the difference in the Level A harassment zone 
size between the minimum and maximum duration anticipated for an 
activity for a given hearing group is quite large. ADOT&PF expressed 
concerns about implementing the largest Level A harassment zones for an 
activity on days where activity levels would be much lower, 
particularly given that the shutdown zones for an activity (Table 9) 
are based upon the Level A harassment zone sizes. Therefore, for low 
frequency cetaceans and phocids, in order to provide flexibility while 
ensuring the number of Level A harassment zones and associated shutdown 
zones are manageable, NMFS has identified two Level A harassment 
isopleths for a given activity in cases where the differences between 
zone sizes associated with the minimum and maximum potential activity 
duration spans >100 m. At the beginning of each pile driving day, 
ADOT&PF will determine the maximum number or duration that piles will 
be driven that day and implement the Level A harassment zone associated 
with that amount of activity.

        Table 7--Distances to Level A Harassment Isopleths, by Hearing Group, and Level B Harassment Zones, During Pile Installation and Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Level A harassment Isopleths, by hearing group (m)
                                                                           -----------------------------------------------------------------
                                                                                 LF           MF           HF           PW           OW
                                                              Max. daily   -----------------------------------------------------------------   Level B
                                                 Pile          duration/       Minke                                                          harassment
                 Activity                     diameter(s)      number of     whale, fin    Pacific       Harbor       Harbor                   isopleth
                                               (inches)         piles *        whale,    white-sided   porpoise,      seal,     Steller sea  (m; hearing
                                                                              humpback     dolphin,      Dall's      northern       lion       groups)
                                                                            whale, gray     killer      porpoise     elephant
                                                                               whale        whale                      seal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation or Removal.........              30           <=360         48.6          4.3         71.8         29.5          2.1       11,659
                                                  24 or 14           <=480         37.1          3.3         54.9         22.6          1.6        7,356
DTH (Rock Socket).........................              24           <=120        210.3         27.8        392.8        107.1         29.8        2,572
                                                                   121-180  ...........  ...........  ...........        214.9  ...........  ...........
                                                                   181-480        344.3  ...........  ...........  ...........  ...........  ...........
DTH (Tension Anchor)......................               8           <=480        118.7          6.4        138.4         68.6          6.9        1,274
Impact, 200 strikes.......................              30               1        542.1         25.3        846.2        182.8         27.7        2,154
                                                                         2  ...........  ...........  ...........        380.2  ...........  ...........
                                                                         3        710.4  ...........  ...........  ...........  ...........  ...........

[[Page 63075]]

 
                                                  24 or 14               1        136.0         10.1        336.9         72.8         11.0        1,000
                                                                         2        282.8  ...........  ...........        151.4  ...........  ...........
                                                                         3  ...........  ...........  ...........  ...........  ...........  ...........
Impact, 50 strikes........................        24 or 14             1-3        112.2          4.0        133.7         60.1          4.4        1,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
* For low frequency cetaceans and phocids, in cases where the Level A harassment zone spanned >=100 m between the minimum and maximum duration for the
  same activity, NMFS analyzed a shorter activity duration to allow for flexibility.

Marine Mammal Occurrence and Take Estimation

    In this section we provide information about the occurrence of 
marine mammals, including density, or group dynamics of marine mammals, 
that will inform the take calculations. Additionally, we describe how 
the occurrence information is synthesized to produce a quantitative 
estimate of the take that is reasonably likely to occur and authorized. 
Note that take estimates included in ADOT&PF's application reflect 152 
construction days rather than 131 (see Summary of Request section, in 
which it is described that one site has been completed since submission 
of the application). A summary of take, including a percentage of 
population for each of the species, is shown in Table 8.
Minke Whale
    There are no known occurrences of minke whales within the project 
area. No minke whales where reported during ADOT&PF's previous 
construction activities at the project site (ADOT&PF 2021, 2023), nor 
during other recent projects in the Tongass Narrows (e.g., City of 
Ketchikan (COK) Rock Pinnacle Blasting Project, Sitkiewicz 2020, Ward 
Cove Cruise Ship Dock in 2020, Power Systems and Supplies of Alaska, 
2020). However, since their range extends into the project area, and 
they have been observed in southeast Alaska, including in Clarence 
Strait (Dahlheim et al., 2009), it is possible the species could occur 
in the project area. Still, future observations of minke whale in the 
project area are expected to be rare.
    ADOT&PF conservatively requested take by Level B harassment of 
three minke whales every 4 months across the 12 months that the IHA is 
active. NMFS concurs with ADOT&PF's estimated group size and frequency, 
but finds it more appropriate to estimate take according to the number 
of actual months in which construction is planned. As such, NMFS 
conservatively authorizes four takes by Level B harassment (3 minke 
whales x 1.25 months = 4 takes by Level B harassment).
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, especially in combination with the infrequent 
occurrence of minke whales entering the project area, implementation of 
the established shutdown zones is expected to eliminate the potential 
for take by Level A harassment of minke whale. Therefore, ADOT&PF did 
not request take by Level A harassment of minke whale, nor is NMFS 
authorizing any.
Fin Whale
    Fin whales typically inhabit deep, offshore waters and often travel 
in open seas away from coasts, and are often observed in social groups 
of two to seven. However, a single fin whale was recently observed in 
Clarence Strait (Scheurer, personal communication). Since the 
ensonified area extends to the mouth of Tongass Narrows, where it meets 
Clarence Strait, there is a chance that fin whale could occur in the 
project area during construction. As such, NMFS conservatively 
authorizes two takes by Level B harassment of fin whale.
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, especially given the rare occurrence of fin 
whale in the surrounding area, implementation of the established 
shutdown zones is expected to eliminate the potential for take by Level 
A harassment of fin whale. Therefore, ADOT&PF did not request take by 
Level A harassment of fin whale, nor is NMFS authorizing any.
Humpback Whale
    While no systematic studies have documented humpback whale 
abundance near Ketchikan, anecdotal information suggests that this 
species is present in low numbers year-round in Tongass Narrows. 
Additionally, during ADOT&PF's 215 days of monitoring associated with 
previous construction, 80 humpback whales were observed, or 0.37 
humpback whales per day (ADOT&PF 2021, 2023). According to ADOT&PF, the 
average group size was 1.25 humpback whales, and the maximum group size 
was 4.
    ADOT&PF conservatively estimates, and NMFS concurs, that one 
humpback whale may occur in the Level B harassment zone each day of 
planned in-water work (1 humpback whale x 131 days = 131 takes by Level 
B harassment).
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, implementation of the established shutdown zones 
is expected to eliminate the potential for take by Level A harassment 
of humpback whale. Therefore, ADOT&PF did not request take by Level A 
harassment of humpback whale, nor is NMFS authorizing any.
    In the proposed IHA, NMFS anticipated that all takes of humpback 
whale would be of the Central North Pacific stock. Given the revised 
stock structure described in the Description of Marine Mammals in the 
Area of Specified Activities section, NMFS has reanalyzed the potential 
for take of each stock of humpback whale and anticipates that the 
authorized takes would be of the new Hawaii stock and

[[Page 63076]]

new Mexico-North Pacific stock. To determine the number of estimated 
takes of each stock, NMFS assumes that two percent of humpback whales 
occurring in Southeast Alaska are from the Mexico-North Pacific stock 
and the remaining humpback whales are from the Hawai'i stock (Wade et 
al., 2021).
Gray Whale
    Gray whales are rare in the project area and unlikely to occur in 
Tongass Narrows. They were not observed during the Dahlheim et al. 
(2009) surveys of Alaska's inland waters with surveys conducted in the 
spring, summer and fall months. No gray whales where reported during 
ADOT&PF's previous construction activities at the project site (ADOT&PF 
2021, 2023), nor during other recent projects in the Tongass Narrows 
(e.g., COK Rock Pinnacle Blasting Project, Sitkiewicz 2020; Ward Cove 
Cruise Ship Dock in 2020, Power Systems and Supplies of Alaska, 2020). 
However a gray whale could migrate through or near the project, during 
November especially. Gray whales are generally solitary and travel 
together, alone, or in small groups.
    ADOT&PF requested 24 takes by Level B harassment of gray whales (1 
group x 2 gray whales x 12 months that the IHA is active). NMFS concurs 
with ADOT&PF's estimated group size and frequency, but finds it more 
appropriate to base take estimates on planned duration of in-water 
work. As such, NMFS authorizes 10 takes by Level B harassment (1 group 
x 2 gray whales x 5 months = 10 takes by Level B harassment).
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, especially in combination with the low 
occurrence of gray whales in the project area, implementation of the 
planned shutdown zones is expected to eliminate the potential for take 
by Level A harassment of gray whale. Therefore, ADOT&PF did not request 
take by Level A harassment of gray whale, nor is NMFS authorizing any.
Pacific White-Sided Dolphin
    Pacific white-sided dolphins were not observed during the 215 days 
of marine mammal monitoring associated with ADOT&PF's previous 
construction activities at this site (ADOT&PF 2021, 2023). There were 
also no sightings of Pacific white-sided dolphins during previous 
monitoring conducted during other recent construction projects in the 
Tongass Narrows (Sitkiewicz 2020, Power Systems and Supplies of Alaska, 
2020).
    While rare in the inside passageways of Southeast Alaska, a group 
of 164 Pacific white-sided dolphins were observed in the Dixon entrance 
to the south of Tongass Narrows during aerial surveys in 1997 (Muto et 
al. 2018), and this species was also documented in Revillagigedo 
Channel, Behm Canal, and Clarence Strait during surveys conducted from 
April to May between 1991 and 1993 (Dahlheim and Towell 1994). Finally, 
Dalheim et al. (2009) frequently encountered Pacific white-sided 
dolphins in Clarence Strait. Observations were noted most typically in 
open strait environments, near the open ocean. Mean group size was over 
20, with no recorded winter observations nor observations made in the 
Nichols Passage or Behm Canal, located on either side of the Tongass 
Narrows. This observational data, combined with anecdotal information, 
indicates that while Pacific white-sided dolphins are rare in the area, 
they could occur in the project area during construction.
    ADOT&PF requested Level B harassment take of one group of 50 
Pacific white-sided dolphins. However, to remain consistent with mean 
groups sizes detected near Tongass Narrows (Dalheim et al., 2009), NMFS 
is authorizing three groups of 20 pacific white sided dolphins (60 
takes by Level B harassment of Pacific white-sided dolphin).
    ADOT&PF is planning to implement shutdown zones for mid-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Additionally, the Level A harassment isopleths for mid-
frequency cetaceans are quite small, and therefore, shutdown zones 
should be easily implemented. Therefore, especially in combination with 
the low occurrence of Pacific white-sided dolphins in the project area, 
implementation of the established shutdown zones is expected to 
eliminate the potential for take by Level A harassment of Pacific 
white-sided dolphin. Therefore, ADOT&PF did not request take by Level A 
harassment of Pacific white-sided dolphin, nor is NMFS is authorizing 
any.
Killer Whale
    While no systematic studies of killer whales have been conducted in 
or around Tongass Narrows, killer whales are observed in Tongass 
Narrows year-round, and anecdotal reports suggest they are most common 
during the summer Chinook salmon run (May-July) (84 FR 36891, July 30, 
2019). Across the 215 days of monitoring during ADOT&PF's previous 
Tongass Narrows construction activities, a total of 78 killer whales 
were observed, for an observation rate of 0.36 per day (ADOT&PF 2021, 
2023). According to ADOT&PF, the average group size observed was 4.6 
killer whales and the maximum group size was 8.
    While ADOT&PF requested 180 takes by Level B harassment ((1 group x 
12 killer whales x 9 months) + (2 groups x 12 killer whales x 3 months) 
= 180 takes by Level B harassment)), NMFS finds it more appropriate to 
base take estimates off the maximum group size (8 killer whales) 
observed during monitoring of previous construction activities and the 
planned duration of in-water work (5 months). As such, NMFS authorizes 
64 takes by Level B harassment ((2 pods x 8 killer whales x 3 months) + 
(1 pod x 8 killer whales x 2 months) = 64 takes by Level B harassment).
    ADOT&PF is planning to implement shutdown zones for mid-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Additionally, the Level A harassment isopleths for mid-
frequency cetaceans are quite small and therefore shutdown zones should 
be easily implemented. Therefore, implementation of the established 
shutdown zones is expected to eliminate the potential for take by Level 
A harassment of killer whale. Therefore, ADOT&PF did not request take 
by Level A harassment of killer whale, nor is NMFS authorizing any.
Harbor Porpoise
    Abundance data for harbor porpoise in Southeast Alaska were 
collected during 18 seasonal surveys spanning 22 years, from 1991 to 
2012 (Dahlheim et al. 2015). The project area falls within the Clarence 
Strait to Ketchikan region, as identified by this study for the survey 
effort. Harbor porpoise densities in this region in summer were low, 
ranging from 0.01 to 0.02 harbor porpoises/kilometers\2\. During 
ADOT&PF's 215 days of monitoring during previous construction 
activities at this project site, the daily average observations of 
harbor porpoise in the project area was 0.1 (ADOT&PF 2021, 2023). 
According to ADOT&PF, the maximum group size observed during this 
monitoring was five.
    ADOT&PF estimates that two groups of five harbor porpoise may occur 
in the Level B harassment zone across the 12 months that the IHA is 
active. NMFS concurs with ADOT&PF's estimated group size but finds it 
appropriate to increase the frequency of occurrence estimate in the 
Level B harassment zone from two groups per month to three groups per 
month of work. Additionally,

[[Page 63077]]

NMFS finds it more appropriate to estimate take by Level B harassment 
according to the planned duration of in-water work (3 groups x 5 harbor 
porpoises x 5 months = 75 takes by Level B harassment). Additionally, 
ADOT&PF requested take by Level A harassment of one group of five 
harbor porpoise every 4 months across 12 months that the IHA is active. 
However, NMFS finds it more appropriate to estimate take by Level A 
harassment according to the number of months in which the Level A 
harassment zone may extend beyond the established shutdown zone (i.e., 
2.9 months, when DTH systems may be employed to install 24-inch piles, 
or 24-inch and 30-inch piles may be installed with an impact pile 
driver (200 strikes)). As such, NMFS authorizes 15 takes by Level A 
harassment of harbor porpoise (1 group x 5 harbor porpoise x 2.9 months 
= 15 takes by Level B harassment) and 60 takes by Level B harassment 
((3 groups x 5 harbor porpoise x 5 months)-15 takes by Level A 
harassment = 60 takes by Level B harassment).
    In the proposed IHA, NMFS anticipated that all takes of harbor 
porpoise would be of the Southern Southeast Alaska Inland Water stock. 
Given the revised stock structure described in the Description of 
Marine Mammals in the Area of Specified Activities section, NMFS has 
reanalyzed the potential for take of each stock of harbor porpoise and 
anticipates that the authorized takes would be of the new Southern 
Southeast Alaska Inland Waters stock, as that is the only stock that 
overlaps the project area.
Dall's Porpoise
    Dall's porpoise have occasionally been observed during previous 
construction projects completed in Tongass Narrows (Power Systems and 
Supplies of Alaska, 2020), including during ADOT&PF's 215 days of 
monitoring (ADOT&PF 2021, 2023). ADOT&PF reported that the average 
group size observed was 5.6 and the maximum group size was 10. To 
estimate take, ADOT&PF has assumed that Dall's porpoise may occur in 
pods of 15 and across the 12 months that the IHA is active. NMFS finds 
it more appropriate to base take estimates off the maximum group size 
(10 Dall's porpoise) observed during monitoring of previous 
construction activities and according to estimated duration of planned 
pile driving and DTH activities.
    As such, while ADOT&PF estimates that one pod of 15 Dall's porpoise 
may occur within the Level B harassment zone across each of the 12 
months that the IHA is active, NMFS finds it more appropriate to 
conservatively estimate that 2 pods of 10 Dall's porpoise may occur in 
the Level B harassment zone each month in which in-water work is 
planned (2 pod x 10 Dall's porpoise x 5 months = 100).
    Additionally, ADOT&PF has estimated that one pod of 15 Dall's 
porpoise may occur within the Level A harassment zone across the 12 
months that the IHA is active. However, NMFS finds it more appropriate 
to estimate 10 takes by Level A harassment of Dall's porpoise across 
the 2.9 months in which the Level A harassment zone may extend beyond 
the shutdown zone for this species, which could occur when DTH systems 
are employed to install 24-inch piles or an impact pile driver (200 
strikes) is used to install 24-inch and 30-inch piles (1 group x 10 
Dall's porpoise = 10 takes by Level A harassment). Therefore, NMFS is 
authorizing 10 takes by Level A harassment of Dall's porpoise. Finally, 
the authorized take by Level B harassment has been calculated as the 
total calculated Dall's porpoise takes by Level B harassment minus the 
authorized takes by Level A harassment (100 takes by Level B 
harassment-10 takes by Level A harassment = 90 takes by Level B 
harassment). Therefore, NMFS is authorizing 90 takes by Level B 
harassment of Dall's porpoise.
Steller Sea Lion
    Steller sea lions may be found in Tongass Narrows year-round, with 
anecdotal reports suggesting an increase in abundance from March to 
early May during the herring spawning season, and another increase in 
late summer associated with salmon runs. During the 215 days of marine 
mammal monitoring that took place during construction of previous 
components of the Tongass Narrows Project, a total of 322 Steller sea 
lions were observed (ADOT&PF 2021, 2023). According to ADOT&PF, the 
average group size was 1.25 individuals and maximum group size observed 
was five individuals. At least one Steller sea lion was observed during 
each month that monitoring took place. Monitoring during construction 
of the nearby Ward Cove Dock recorded 4.1 individuals per day (Power 
Systems & Supplies of Alaska, 2020).
    ADOT&PF estimates that one group of 10 Steller sea lions may be 
taken by Level B harassment each day that in-water work is planned. 
Based on ADOT&PF's 215 days of project-related monitoring, NMFS finds 
it more appropriate to estimate that 1 group of 5 Steller sea lions may 
be present in the Level B harassment zone each day (1 group x 5 Steller 
sea lion x 131 construction days = 655 takes by Level B harassment).
    ADOT&PF is required to implement a shutdown zone that exceeds the 
Level A harassment zone for Steller sea lions during all project 
activities. However, ADOT&PF expects that Steller sea lions could enter 
the Level A harassment zone undetected on rare occasions. As such, 
ADOT&PF requests take by Level A harassment of 5 percent of Steller sea 
lions authorized for take by Level B harassment. NMFS concurs that, 
given the various structures along the shoreline in the project area, 
Steller sea lions could enter the Level A harassment zone and remain in 
the zone undetected for a long enough duration to incur PTS before a 
shutdown occurs. However, NMFS anticipates that 5 percent of the take 
by Level B harassment would result in an overestimate of Level A 
harassment. NMFS anticipates that 10 Steller sea lions could enter the 
Level A harassment zone and remain in the zone undetected for a long 
enough duration to incur PTS before a shutdown occurs across the 131 
days of planned in-water work. As such, NMFS is authorizing 10 takes by 
Level A harassment and 645 takes by Level B harassment ((1 group x 5 
individuals x 131 construction days)-10 takes by Level A harassment = 
645 takes by Level B harassment).
Northern Elephant Seal
    Although northern elephant seals are known to visit the Gulf of 
Alaska to feed on benthic prey, they rarely occur on the beaches of 
Alaska. Despite the low probability of northern elephant seals entering 
the project area, there have been recent reports of elephant seals 
occurring in and near the Tongass Narrows, and two northern elephant 
seals were observed during ADOT&PF's Tongass Narrows construction in 
2022. As such, ADOT&PF requested take by Level B harassment of one 
elephant seal per 6-day work week. NMFS concurs that one take by Level 
B harassment per work week is appropriate. However, because ADOT&PF 
plans 7-day work weeks, NMFS calculates the total number of work weeks 
to occur within 131 construction days as 19 weeks rather than ADOT&PF's 
planned 22 weeks (1 Northern elephant seal x 19 work weeks = 19 takes 
by Level B harassment).
    For most project activities, the established shutdown zone will 
exceed the Level A harassment zone for Northern elephant seal. However, 
the Level A harassment zone may extend beyond the established shutdown 
zone for this species on 37 days (when DTH systems may be employed to 
install 24-

[[Page 63078]]

inch piles or 30-inch piles may be installed with an impact pile driver 
(200 strikes)). While unlikely given the already low occurrence of 
Northern elephant seals, on those days, a Northern elephant seal could 
occur in the Level A harassment zone and remain in the zone for a long 
enough duration to incur PTS, and NMFS is conservatively authorizing 
five takes by Level A harassment. As such, NMFS is authorizing 14 takes 
by Level B harassment (1 Northern elephant seal x 19 work weeks-5 takes 
by Level A harassment = 14 takes by Level B harassment).
Harbor Seal
    During marine mammal monitoring associated with ADOT&PF's previous 
Tongass Narrows construction activities, 550 harbor seals were observed 
with an average of 1.2 harbor seals per day and a maximum group size of 
5. The COK pinnacle rock blasting project recorded a total of 21 harbor 
seal sightings of 24 individuals over 76.2 hours of pre- and post-blast 
monitoring (Sitkiewicz 2020). Additionally, information from PSOs 
associated with on-going construction indicates that a small number of 
harbor seals are regularly sighted at about 820 ft (250 m) from the 
project location (Wyatt, personal communication). Additionally, there 
are two key harbor seal haulouts about 7.1 miles (11.5 kilometers) from 
the project area on a mid-channel island to the southeast of the 
project site. Each haulout was monitored in 2022 with 10 harbor seals 
observed at one haulout and 50 harbor seals observed at the other 
(Richland, personal communication).
    ADOT&PF estimates, and NMFS concurs, that up to 2 groups of 3 
harbor seals could enter the Level B harassment zone per day (2 groups 
x 3 harbor seals x 131 days = 786). Further, NMFS also estimates that 
half the harbor seals occurring at the haulout sites within the project 
area could enter the Level B harassment zone on days when the 
ensonified area (during 30'' vibratory pile driving) reaches these 
haulout sites (30 harbor seals x 13 days = 390).
    ADOT&PF also estimates that 1 harbor seal could be taken by Level A 
harassment on each day of in-water work (1 harbor seal x 131 days = 131 
takes by Level A harassment). For most project activities, the shutdown 
zone exceeds the Level A harassment zone. However, when an impact pile 
driver (200 strikes) is used to install 30-inch piles, the Level A 
harassment zone exceeds the associated shutdown zone. This could occur 
on 13 days. NMFS anticipates that three harbor seals could be taken by 
Level A harassment on each day that the Level A harassment isopleth for 
this species extends beyond the shutdown zone. Therefore, NMFS is 
authorizing 39 takes by Level A harassment (3 harbor seal x 13 days = 
39 takes by Level A harassment) and 1,137 takes by Level B harassment 
(786 takes by Level B harassment + 390 takes by Level B harassment - 39 
takes by Level A harassment = 1,137 takes by Level B harassment).

          Table 8--Authorized Take by Stock and Harassment Type and as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
                                                                          Authorized take       Authorized take
                                                                    --------------------------  as a percentage
                Species                             Stock              Level B      Level A         of stock
                                                                      harassment   harassment      abundance
----------------------------------------------------------------------------------------------------------------
Minke whale............................  Alaska....................            4            0  .................
Fin whale..............................  Northeast Pacific.........            2            0                0.1
Humpback whale.........................  Hawai[revaps]i \1\........          128            0                1.1
                                         Mexico--North Pacific \1\.            3            0  .................
Gray whale.............................  Eastern North Pacific.....           10            0               0.04
Pacific white-sided dolphin............  North Pacific.............           60            0                0.2
Killer whale...........................  Eastern North Pacific                64            0                3.3
                                          Alaska Resident.
                                         Eastern North Pacific       ...........  ...........               21.2
                                          Northern Resident.
West Coast Transient...................  ..........................  ...........  ...........               16.3
Harbor porpoise........................  Southern Southeast Alaska            60           15                8.4
                                          Inland \2\.
Dall's porpoise........................  Alaska....................           90           10                0.8
Steller sea lion.......................  Eastern U.S...............          645           10                1.5
Northern Elephant seal.................  California Breeding.......           14            5               <0.1
Harbor seal............................  Clarence Strait...........        1,137           39                4.3
----------------------------------------------------------------------------------------------------------------
\1\ Given the revised stock structure for humpback whale, described in the Description of Marine Mammals in the
  Area of Specified Activities section, NMFS assumes that two percent of humpback whales occurring in Southeast
  Alaska are from the Mexico--North Pacific stock and the remaining humpback whales are from the Hawai[revaps]i
  stock (Wade et al., 2021).
\2\ Given the revised stock structure described in the Description of Marine Mammals in the Area of Specified
  Activities section, NMFS assumed all the authorized takes would be of the new Southern Southeast Alaska Inland
  Waters stock, as that is the only stock that overlaps the project area.

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. 
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

[[Page 63079]]

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.
    ADOT&PF must ensure that construction supervisors and crews, the 
monitoring team and relevant ADOT&PF staff are trained prior to the 
start of all pile driving and DTH activity, so that responsibilities, 
communication procedures, monitoring protocols, and operational 
procedures are clearly understood. New personnel joining during the 
project must be trained prior to commencing work.

Protected Species Observers

    ADOT&PF must employ PSOs and establish monitoring locations as 
described in the NMFS-approved Marine Mammal Monitoring Plan and 
Section 5 of the IHA. ADOT&PF must monitor the project area to the 
maximum extent possible based on the required number of PSOs, required 
monitoring locations, and environmental conditions. For all vibratory 
pile driving and removal, ADOT&PF must employ at least three PSOs. For 
all impact pile driving and DTH, ADOT&PF must employ at least two PSOs. 
As noted in the Changes from the Proposed IHA to Final IHA section, in 
the proposed IHA, NMFS proposed to require ADOT&PF to employ three PSOs 
for DTH activities. After publication of the proposed IHA, ADOT&PF 
requested for NMFS to revise this measure to require two PSOs for DTH 
activities, given that the zone sizes for DTH activities were more 
commensurate with that of impact pile driving. NMFS concurred, and 
therefore, the final IHA requires ADOT&PF to employ at least two PSOs 
for DTH activities, rather than three. The placement of the PSOs during 
all pile driving and removal and DTH activities will ensure that the 
entire shutdown zone is visible.

Pre- and Post-Activity Monitoring

    Monitoring must take place from 30 minutes prior to initiation of 
pile driving or DTH activity (i.e., pre-clearance monitoring) through 
30 minutes post-completion of pile driving or DTH 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 9 are clear of marine mammals. Pile driving may 
commence following 30 minutes of observation when the determination is 
made that the shutdown zones are clear of marine mammals. Further, 
while not a requirement in the IHA, the 2023 Biological Opinion 
requires that if a work stoppage occurs and PSOs do not monitor the 
boundaries of the Level B harassment zone continuously during the work 
stoppage, the entire Level B harassment zone must be surveyed again for 
the presence of ESA-listed species before work may resume. 
Additionally, the 2023 Biological Opinion requires that in-water 
activities take place only between civil dawn and civil dusk when PSOs 
can effectively monitor for the presence of marine mammals and when the 
entire shutdown zone and adjacent waters are visible (e.g., monitoring 
effectiveness is not reduced due to rain, fog, snow, etc.). The 2023 
Biological Opinion allows for pile driving to continue for up to 30 
minutes after sunset during evening civil twilight, as necessary to 
secure a pile for safety prior to demobilization for the evening. PSOs 
will continue to observe shutdown and monitoring zones during this 
time. The length of the post-activity monitoring period may be reduced 
if darkness precludes visibility of the shutdown and monitoring zones.

Soft Start

    Soft-start procedures 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. ADOT&PF 
must use soft start techniques when 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.

Shutdown Zones

    For all pile driving/removal and DTH activities, ADOT&PF will 
establish shutdown zones (Table 9). The purpose of a shutdown zone is 
generally to define an area within which shutdown of activity will 
occur upon sighting of a marine mammal (or in anticipation of an animal 
entering the defined area). Shutdown zones vary based on the activity 
type and duration and marine mammal hearing group (Table 9). In most 
cases, shutdown zones are based on the estimated Level A harassment 
isopleth distances for each hearing group. However, in cases where 
ADOT&PF asserted that it would be impracticable to shut down at the 
Level A harassment isopleth due to excessive work stoppages, a smaller 
shutdown zone has been established (e.g., for high-frequency cetaceans 
and phocids during DTH rock socketing of 24-inch piles). Note that some 
of the established shutdown zones differ from those proposed by the 
ADOT&PF in their application (see Table 6-5 of ADOT&PF's application) 
due to our incorporation of sound source levels and DTH TL coefficients 
from ADOT&PF's SSV report.
    ADOT&PF anticipates that the maximum amount of activity within a 
given day may vary significantly (Table 6), with large differences in 
maximum zones sizes possible (Table 7). Given this uncertainty and 
concerns related to ESA-listed humpback whales and fin whales, and 
practicability concerns with shutting down, ADOT&PF plans a tiered 
system to identify and monitor the appropriate Level A harassment zones 
and shutdown zones for large frequency cetaceans and phocids. This 
tiered system is based on the maximum expected number of piles to be 
installed (impact or vibratory pile driving) or the maximum expected 
DTH duration in a given day. At the start of each work day, ADOT&PF 
will determine the maximum scenario possible for that day (according to 
the defined duration intervals in Tables 7 and 9), which will determine 
the appropriate Level A harassment isopleth and associated shutdown 
zone for that day. This Level A harassment zone (Table 7) and 
associated shutdown zone (Table 9) must be implemented for the entire 
work day.
    The placement of PSOs during all pile installation and removal, and 
DTH activities (described in detail in the Monitoring and Reporting 
section) will ensure that the entire shutdown zones are visible during 
pile driving. If a marine mammal is observed entering or within the 
shutdown zones indicated in Table 9, pile driving 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 (Table 9) or 15 minutes (non-ESA-listed species) or 30 
minutes (humpback whales and fin whales) have passed without re-
detection of the animal. Further, pile driving activity must be halted 
upon observation of either a species for which incidental take is not 
authorized or a species for which incidental take has been authorized 
but the authorized number of takes has been met, entering or within the 
harassment zone.
    ADOT&PF must also avoid direct physical interaction with marine

[[Page 63080]]

mammals during construction activity. If a marine mammal comes within 
10 m of such activity, operations must cease and vessels must reduce 
speed to the minimum level required to maintain steerage and safe 
working conditions.

                                                                      Table 9--Shutdown Zones and Level B Harassment Zones
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                  Duration (min;                              Shutdown distances (m)
                                                                                  vibratory/DTH)/--------------------------------------------------------------------------------     Level B
                  Activity                         Pile diameter(s) (inches)        # of piles                                                                                      harassment
                                                                                     (impact)           LF              MF              HF              PW              OW         isopleth (m)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation or Removal, temporary  30................................           <=360              50              10              80              30              10          11,659
 and permanent.                               24 or 14..........................           <=480              40              10              60              30              10           7,365
DTH (Rock Socket)...........................  24................................           <=120             220              30             300             110              30           2,572
                                                                                         121-180  ..............  ..............  ..............             220  ..............  ..............
                                                                                         181-480             350  ..............  ..............  ..............  ..............  ..............
DTH (Tension Anchor)........................  8.................................           <=480             170              10             140              70              10           1,274
Impact permanent............................  30................................               1             550              30             300             190              30           2,154
                                                                                               2  ..............  ..............  ..............             300  ..............  ..............
                                                                                               3             720  ..............  ..............  ..............  ..............  ..............
                                              24 or 14..........................               1             140              10             300              80              20           1,000
                                                                                               2             290  ..............  ..............             160  ..............  ..............
                                                                                               3  ..............  ..............  ..............  ..............  ..............  ..............
Impact, temporary...........................  24 or 14..........................             1-3             120              10             140              60              10           1,000
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on our evaluation of the applicant's planned measures, as 
well as other measures considered by NMFS, NMFS has determined that the 
required mitigation measures provide the means effecting the least 
practicable impact on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, and areas of 
similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Monitoring must be conducted by qualified, NMFS-approved PSOs, who 
will be present during all pile installation and removal activities, 
including vibratory, impact, and DTH methods, in accordance with the 
following:
     PSOs must be independent (i.e., not construction 
personnel) 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 
IHA;
     Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field), or training 
for prior experience performing the duties of a PSO during construction 
activity pursuant to a NMFS-issued IHA;
     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 should 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 of 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.
    A minimum of one PSO (the lead PSO) must be assigned to the active 
pile driving or DTH location to monitor the shutdown zones and as much 
of the harassment zones as possible. The observation points of the 
additional

[[Page 63081]]

PSOs may vary depending on the construction activity and location of 
the piles. During impact pile driving or DTH activities, the second PSO 
will select the best location to observe as much of the Level A 
harassment and Level B harassment zones as possible. To select the best 
observation locations during vibratory installation and removal, prior 
to start of construction, the lead PSO will stand at the construction 
site to monitor the shutdown zones while two or more PSOs travel in 
opposite directions from the project site along Tongass Narrows until 
they have reached the edge of the Level B harassment zone, where they 
will identify suitable observation points from which to observe. If 
visibility deteriorates so that the entire width of Tongass Narrows at 
the harassment zone boundary is not visible, additional PSOs may be 
positioned so that the entire width is visible, or work will be halted 
until the entire width is visible to ensure that any humpback whales or 
fin whales entering or within the harassment zone are detected by PSOs.
    PSOs must record all observations of marine mammals, regardless of 
distance from the pile being driven. PSOs shall document any behavioral 
reactions in concert with distance from piles being driven or removed.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance of any 
future IHAs for projects at the same location, whichever comes first. 
The report will include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact, vibratory or DTH), the total 
equipment duration for vibratory installation/removal or DTH for each 
pile or hole and total 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: Name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting; Time of sighting; Identification of the 
animal(s) (e.g., genus/species, lowest possible taxonomic level, or 
unidentified), PSO confidence in identification, and the composition of 
the group if there is a mix of species; Distance and bearing of each 
marine mammal observed relative to the pile being driven for each 
sighting (if pile driving was occurring at time of sighting); Estimated 
number of animals (min/max/best estimate); Estimated number of animals 
by cohort (adults, juveniles, neonates, group composition, sex class, 
etc.); Animal's closest point of approach and estimated time spent 
within the harassment zone; 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;
     Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    ADOT&PF must also submit all PSO datasheets and/or raw sighting 
data with the draft report, as specified in condition 6(b) of this IHA.
    If no comments are received from NMFS within 30 days, the draft 
report will constitute the final report. If comments are received, a 
final report addressing NMFS comments must be submitted within 30 days 
after receipt of comments.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the IHA-holder must 
immediately cease the specified activities and report the incident to 
the Office of Protected Resources (OPR), NMFS and to the NMFS 24-hour 
Stranding Hotline as soon as feasible. If the death or injury was 
clearly caused by the specified activity, ADOT&PF must immediately 
cease the specified activities until NMFS 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 the 
IHA. The IHA-holder must not resume their activities until notified by 
NMFS. The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

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 1, given that many of the

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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, NMFS has identified species-specific factors to 
inform the analysis.
    Pile driving and DTH 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 and, for some species Level A 
harassment, from underwater sounds generated by pile driving and DTH. 
Potential takes could occur if marine mammals are present in zones 
ensonified above the thresholds for Level B harassment or Level A 
harassment, identified above, while activities are underway.
    NMFS does not anticipate that serious injury or mortality will 
occur as a result of ADOT&PF's planned activity given the nature of the 
activity, even in the absence of required mitigation. Further, no take 
by Level A harassment is anticipated for Pacific white-sided dolphin, 
killer whale, humpback whale, gray whale, fin whale, or minke whale, 
due to the likelihood of occurrence and/or required mitigation 
measures. As stated in the mitigation section, ADOT&PF will implement 
shutdown zones that equal or exceed many of the Level A harassment 
isopleths shown in Table 9. Take by Level A harassment is authorized 
for some species (Steller sea lion, harbor seal, northern elephant 
seal, harbor porpoise, and Dall's porpoise) to account for the 
potential that an animal could enter and remain within the area between 
a Level A harassment zone and the shutdown zone for a duration long 
enough to be taken by Level A harassment, and in some cases, to account 
for the possibility that an animal could enter a shutdown zone without 
detection given the various obstructions along the shoreline, and 
remain in the Level A harassment zone for a duration long enough to be 
taken by Level A harassment before being observed and a shutdown 
occurring. Any take by Level A harassment is expected to arise from, at 
most, a small degree of PTS because animals would need to be exposed to 
higher levels and/or longer duration than are expected to occur here in 
order to incur any more than a small degree of PTS. Additionally, and 
as noted previously, some subset of the individuals that are 
behaviorally harassed could also simultaneously incur some small degree 
of TTS for a short duration of time. Because of the small degree 
anticipated, though, any PTS or TTS potentially incurred here is not 
expected to adversely impact individual fitness, let alone annual rates 
of recruitment or survival.
    For all species and stocks, take is expected to occur within a 
limited, confined area (adjacent to the project site) of the stock's 
range. The intensity and duration of take by Level A harassment and 
Level B harassment will be minimized through use of mitigation measures 
described herein. Further the amount of take authorized is small when 
compared to stock abundance.
    Behavioral responses of marine mammals to pile driving, pile 
removal, and DTH at the sites in Tongass Narrows are expected to be 
mild, short term, and temporary. Marine mammals within the Level B 
harassment zones may not show any visual cues they are disturbed by 
activities or they could become alert, avoid the area, leave the area, 
or display other mild responses that are not visually observable such 
as changes in vocalization patterns. Given that pile driving, pile 
removal, and DTH will occur for only a portion of the project's 
duration and often on nonconsecutive days, any harassment would be 
temporary. Additionally, many of the species present in Tongass Narrows 
would only be present temporarily based on seasonal patterns or during 
transit between other habitats. These species would be exposed to even 
shorter periods of noise-generating activity, further decreasing the 
impacts.
    As previously described, a UME has been declared for gray whales. 
However, we do not expect the takes authorized herein to exacerbate the 
ongoing UME. No serious injury or mortality of gray whales is expected 
or authorized, and take by Level B harassment is limited (10 takes over 
the duration of the authorization). As such, the authorized take by 
Level B harassment of gray whale is not expected to exacerbate or 
compound upon the ongoing UME.
    For all species except humpback whales, there are no known BIAs 
near the project zone that will be impacted by ADOT&PF's planned 
activities. For humpback whales, the inland waters of Southeast Alaska 
is a seasonal feeding BIA from May through September (Wild et al., 
2023), however, the mouth of Tongass Narrows is a small passageway and 
represents a very small portion of the total available habitat. Also, 
while southeast Alaska is considered an important area for feeding 
humpback whales during this time, it is not currently designated as 
critical habitat for humpback whales (86 FR 21082, April 21, 2021).
    More generally, there are no known calving or rookery grounds 
within the project area, but anecdotal evidence from local experts 
shows that marine mammals are more prevalent in Tongass Narrows and 
Clarence Strait during spring and summer associated with feeding on 
aggregations of fish, meaning the area may play a role in foraging. 
Because ADOT&PF's activities could occur during any season, takes may 
occur during important feeding times. However, the project area 
represents a small portion of available foraging habitat and impacts on 
marine mammal feeding for all species, including humpback whales, 
should be minimal.
    Any impacts on marine mammal prey that occur during ADOT&PF's 
planned activity are expected to have, at most, short-term effects on 
foraging of individual marine mammals, and likely no effect on the 
populations of marine mammals as a whole. Indirect effects on marine 
mammal prey during the construction are expected to be minor, and these 
effects are unlikely to cause substantial effects on marine mammals at 
the individual level, with no expected effect on annual rates of 
recruitment or survival.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat will have any effect on the reproduction or 
survival of any individuals, much less the stocks' annual rates of 
recruitment or survival. In combination, we believe that these factors, 
as well as the available body of evidence from other similar 
activities, demonstrate that the potential effects of the specified 
activities will have only minor, short-term effects on individuals. The 
specified activities are not expected to impact rates of recruitment or 
survival and will, therefore, not result in population-level impacts.
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect any of the species or stocks 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     Take by Level A harassment of Pacific white-sided dolphin, 
killer whale, humpback whale, fin whale, gray whale, or minke whale is 
not anticipated or authorized;
     ADOT&PF will implement mitigation measures including soft-
starts for impact pile driving and shutdown zones to minimize the 
numbers of marine mammals exposed to

[[Page 63083]]

injurious levels of sound, and to ensure that any take by Level A 
harassment is, at most, a small degree of PTS;
     The intensity of anticipated takes by Level B harassment 
is relatively low for all stocks and will not be of a duration or 
intensity expected to result in impacts on reproduction or survival;
     There are 10 known areas of specific biological 
importance, covering a broad area of southeast Alaska, for humpback 
whales. The project area overlaps a very small portion of one of these 
BIAs. No other known areas of particular biological importance to any 
of the affected species or stocks are impacted by the activity, 
including ESA-designated critical habitat;
     The project area represents a very small portion of the 
available foraging area for all potentially impacted marine mammal 
species and stocks and anticipated habitat impacts are minor; and
     Monitoring reports from similar work in Tongass Narrows 
have documented little to no effect on individuals of the same species 
impacted by the specified activities.
    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 monitoring and mitigation 
measures, NMFS finds that the total marine mammal take from the planned 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

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 authorized number of instances of take is below one-third of 
the estimated stock abundance for all stocks (see Table 8). The number 
of animals authorized to be taken from these stocks would be considered 
small relative to the relevant stocks' abundances even if each 
estimated taking occurred to a new individual, which is an unlikely 
scenario. Some individuals may return multiple times in a day, but PSOs 
will count them as separate takes if they cannot be individually 
identified.
    The Alaska stock of Dall's porpoise has no official NMFS abundance 
estimate, as the most recent estimate is greater than 8 years old. The 
most recent estimate was 13,110 animals for just a portion of the 
stock's range. Therefore, the 100 authorized takes of this stock 
clearly represent small numbers of this stock.
    The Mexico--North Pacific stock of Humpback Whale has no official 
NMFS abundance estimate, as the most recent estimate is greater than 8 
years old. The most recent estimate was 571 animals for just a portion 
of the stock's range (Revillagigedo Archipelago). Therefore, the three 
takes of this stock authorized clearly represent small numbers of this 
stock.
    There is no current or historical estimate of the Alaska minke 
whale stock, but there are known to be over 1,000 minke whales in the 
Gulf of Alaska (Muto et al. 2018), so the 4 takes authorized is small 
relative to estimated survey abundance, even if each take occurred to a 
new individual. Additionally, the range of the Alaska stock of minke 
whales is extensive, stretching from the Canadian Pacific coast to the 
Chukchi Sea, and ADOT&PF's project area will impact a small portion of 
this range.
    The best available abundance estimate for fin whale is not 
considered representative of the entire stock as surveys were limited 
to a small portion of the stock's range, but there are known to be over 
2,500 fin whales in the northeast Pacific stock (Muto et al. 2021). As 
such, the two takes authorized is small relative to the estimated 
survey abundance, even if each take occurred to a new individual.
    Based on the analysis contained herein of the planned activity 
(including the mitigation and monitoring measures) and the anticipated 
take of marine mammals, NMFS finds that small numbers of marine mammals 
are expected to 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.
    Harbor seals are the marine mammal species most regularly harvested 
for subsistence by households in Ketchikan and Saxman (a community a 
few miles south of Ketchikan, on the Tongass Narrows). Eighty harbor 
seals were harvested by Ketchikan residents in 2007, which ranked 
fourth among all communities in Alaska that year for harvest of harbor 
seals. Thirteen harbor seals were harvested by Saxman residents in 
2007. In 2008, two Steller sea lions were harvested by Ketchikan-based 
subsistence hunters, but this is the only record of sea lion harvest by 
residents of either Ketchikan or Saxman. In 2012, the community of 
Ketchikan had an estimated subsistence take of 22 harbor seals and 0 
Steller sea lion (Wolf et al. 2013). NMFS is not aware of more recent 
data. Hunting usually occurs in October and November (Alaska Department 
of Fish and Game (ADF&G) 2009), but there are also records of 
relatively high harvest in May (Wolfe et al. 2013). The ADF&G has not 
recorded harvest of cetaceans from Ketchikan or Saxman (ADF&G 2023).
    All project activities are planned to take place within the 
industrial area of Tongass Narrows immediately adjacent to Ketchikan 
where subsistence activities do not generally occur. Both harbor seals 
and Steller sea lions may be temporarily displaced from the project 
area. The project will also not have an adverse impact on the 
availability of marine mammals for subsistence use at locations farther 
away where these construction activities are not expected to take 
place. Some minor, short-term harassment of the harbor seals could 
occur, but given the information above, we do not expect such 
harassment to have effects on subsistence hunting activities.
    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 mitigation and monitoring 
measures,

[[Page 63084]]

NMFS has determined that there will not be an unmitigable adverse 
impact on subsistence uses from ADOT&PF's planned 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 consults internally whenever we plan to authorize take for 
endangered or threatened species, in this case with NMFS' Alaska 
Regional Office (AKRO).
    NMFS is authorizing take of the Mexico--North Pacific stock of 
humpback whale, and fin whale, which are listed as threatened or 
endangered under the ESA. The NMFS AKRO issued a Biological Opinion 
under section 7 of the ESA on the issuance of an IHA to ADOT&PF under 
section 101(a)(5)(D) of the MMPA by NMFS OPR. The biological opinion 
concluded that the action is not likely to jeopardize the continued 
existence of the listed species.

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 proposed actions (i.e., the issuance of an IHA) with 
respect to potential impacts on the human environment. This action is 
consistent with categories of activities identified in Categorical 
Exclusion B4 (IHAs with no anticipated serious injury or mortality) of 
the Companion Manual for 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 determined that the 
issuance of the IHA qualifies to be categorically excluded from further 
NEPA review.

Authorization

    NMFS has issued an IHA to ADOT&PF for the potential harassment of 
small numbers of 11 marine mammal species incidental to ferry berth 
construction in Tongass Narrows in Ketchikan, Alaska, that includes the 
previously explained mitigation, monitoring, and reporting 
requirements.

    Dated: September 11, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-19903 Filed 9-13-23; 8:45 am]
BILLING CODE 3510-22-P