[Federal Register Volume 89, Number 6 (Tuesday, January 9, 2024)]
[Notices]
[Pages 1066-1082]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-00189]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD284]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Hydaburg Seaplane Base 
Refurbishment Project in Hydaburg, Alaska

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

ACTION: Issuance of an incidental harassment authorization.

-----------------------------------------------------------------------

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 (DOT&PF) 
to incidentally harass marine mammals during construction associated 
with the Hydaburg Seaplane Base Refurbishment Project in Hydaburg, 
Alaska.

DATES: This authorization is effective from September 15, 2024 through 
September 14, 2025.

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: Reny Tyson Moore, 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.

[[Page 1067]]

Summary of Request

    On June 28, 2022, NMFS received a request from DOT&PF for an IHA to 
take marine mammals incidental to the Hydaburg Seaplane Base 
Refurbishment Project in Hydaburg, Alaska. Following NMFS' review of 
the application, and multiple discussions between DOT&PF and NMFS, 
DOT&PF submitted responses to NMFS questions on December 15, 2022 and a 
revised application on February 22, 2023. The application was deemed 
adequate and complete on March 13, 2023. DOT&PF's request is for take 
of nine species of marine mammals by Level B harassment and, for a 
subset of 6 of these species, Level A harassment. Neither DOT&PF nor 
NMFS expect serious injury or mortality to result from this activity 
and, therefore, an IHA is appropriate.

Description of Activity

Overview

    DOT&PF, in cooperation with the Federal Aviation Administration, is 
planning maintenance improvements to the existing Hydaburg Seaplane 
Base as part of the Hydaburg Seaplane Base Refurbishment Project. The 
existing facility has experienced deterioration in recent years, and 
DOT&PF has conducted several repair projects. The facility is near the 
end of its useful life, and replacement of the existing float 
structures is required to continue safe operation in the future. The 
in-water portion of the project will include the removal of five 
existing steel piles and installation of eight permanent steel piles to 
support replacement of the floating dock structure (Table 1). Up to 10 
temporary steel piles will be installed to support permanent pile 
installation and will be removed following completion of permanent pile 
installation (Table 1). Activities included as part of the project with 
potential to affect marine mammals include vibratory removal, down-the-
hole (DTH) installation, and vibratory and impact installation of steel 
pipe piles. Pile installation and removal will occur intermittently 
over 26 nonconsecutive days within a 2-month construction window, and 
is anticipated to begin in fall 2024.

                                                                      Table 1--Summary of Piles To Be Installed and Removed
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                          Rock socket   Tension anchor
                                                                                                             Vibratory     DTH pile        DTH pile         Total        Typical
                                                                Number of  Number of  Number of    Impact    duration    installation,   installation,   duration of   production      Days of
                    Pile diameter and type                        piles       rock     tension    strikes    per pile    duration per    duration per   activity per     rate in    installation
                                                                            sockets    anchors    per pile   (minutes)   pile, minutes   pile, minutes   pile, hours    piles per    or removal
                                                                                                                            (range)         (range)                    day (range)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        Pile Installation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
24'' Steel Plumb Piles (Permanent)............................          4          4          4         50          15    240 (60-480)    120 (60-240)          6.75     0.5 (0-1)             8
20'' Steel Plumb Piles (Permanent)............................          4          2          2         50          15    240 (60-480)    120 (60-240)     \1\ 0.75/     0.5 (0-1)             8
                                                                                                                                                                6.75
24'' Steel Piles (Temporary)..................................         10          5        N/A        N/A          15    240 (60-480)             N/A          4.25    2.5 (1-10)             4
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          Pile Removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
16'' Steel Cantilevered Piles.................................          5        N/A        N/A        N/A          30             N/A             N/A           0.5     2.5 (2-4)             2
24'' Steel Piles (Temporary)..................................         10        N/A        N/A        N/A          30             N/A             N/A           0.5     2.5 (2-4)             4
                                                               ---------------------------------------------------------------------------------------------------------------------------------
    Totals....................................................         23         11          6        N/A         N/A             N/A             N/A           N/A           N/A            26
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Two of the 20-inch plumb piles will include vibratory and impact installation in addition to rock sockets and tension anchors, estimated at 6.75 hours duration total, and two will only use
  vibratory and impact, estimated at 0.75 hours duration total.

    A detailed description of the planned construction project is 
provided in the Federal Register notice for the proposed IHA (88 FR 
45774, June 17, 2023). Since that time, no changes have been made to 
the planned activities. Therefore, a detailed description is not 
provided here. Please refer to that Federal Register notice for the 
description of the specific activity.
    Mitigation, monitoring, and reporting measures are described in 
detail later in this document (please see Mitigation and Monitoring and 
Reporting).

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to the DOT&PF was 
published in the Federal Register on July 17, 2023 (88 FR 45774). That 
notice described, in detail, the DOT&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. This proposed notice was available for a 30-
day public comment period.
    In the Federal Register notice of the proposed IHA, NMFS presented 
our assessment of DTH systems, which differed from DOT&PF's assessment. 
Specifically, the DOT&PF and NMFS disagreed about some of the source 
levels and transmission loss (TL) coefficients that should be used as 
proxies to estimate the ensonified area resulting from certain DTH 
activities. NMFS also disagreed with the DOT&PF's assessment that 
sounds resulting from the DTH installation of 8 inch anchor piles 
should only be considered as continuous sound sources when calculating 
Level A and Level B harassment rather than as having both impulsive and 
continuous components as recommended by NMFS (2022) (https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf). Available data 
does not support DOT&PF's evaluation. NMFS' recommendations regarding 
analysis of sound produced through use of DTH techniques is based on 
the best available science and interpretation of available data by 
subject matter experts, and is publicly available online. NMFS 
explained these issues in the notice of the proposed IHA, and 
specifically

[[Page 1068]]

requested public comment on its DTH-related recommendations in context 
of DOT&PF's alternative interpretation.
    During the 30-day public comment period, NMFS received comments 
from the Marine Mammal Commission (MMC). The MMC expressed support for 
NMFS' assessment and evaluation of DTH systems. Specifically, the MMC 
agrees with NMFS that DTH installation of all sized piles, including 8-
inch tension anchors, should be considered an impulsive, continuous 
source and that NMFS should the use proxy source levels recommended by 
NMFS (2022) instead of those proposed by the DOT&PF to estimate 
associated ensonified areas. In addition, the MMC agrees with NMFS' 
determination that applying proxy TL coefficients measured in other 
locations in Hydaburg is inappropriate, because transmission loss is 
dependent on sediment characteristics, bathymetry/water depth, and 
sound speed profiles in a given area. The MMC supports NMFS' decision 
to require the DOT&PF to use practical spreading loss models (i.e., 15 
log R) when calculating ensonified areas resulting from DTH pile 
installation at Hydaburg, and recommends that NMFS continue to require 
action proponents to use practical spreading unless site-specific 
transmission loss data are available from the proposed project site. 
The comments and recommendations are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. Please see the comment 
submission for full details regarding the recommendations and 
supporting rationale.

Changes From the Proposed IHA to Final IHA

    Since the Federal Register notice of the proposed IHA was published 
(88 FR 45774, July 17, 2023), NMFS published the 2022 Alaska and 
Pacific Stock Assessment Reports (SARs), which provide updates to the 
humpback whale stock structure and Southeast Alaska harbor porpoise 
stock structure (Carretta et al., 2023; Young et al, 2023). Updates 
have been made to the species descriptions for these species (see 
Description of Marine Mammals in the Area of Specified Activities) as 
well as to our analysis of take (see Estimated Take) and small numbers 
determinations (see Small Numbers).
    In addition, based on the comment letter received from the MMC in 
support of NMFS' assessment of DTH systems, the Estimated Take section 
in this notice only considers source levels and transmission loss 
coefficients recommended by NMFS (2022) for DTH systems as proxies to 
estimate associated ensonified areas (in contrast to including a 
discussion regarding the DOT&PF's assessment of DTH systems). 
Specifically, DTH installation of all sized piles are considered to be 
an impulsive, continuous source; proxy source levels follow NMFS's 
recommendations for DTH systems (NMFS, 2022); and transmission loss of 
sounds produced by DTH systems in the Hydaburg project area are 
modelled assuming practical spreading loss.
    Lastly, a typographical error identified in Table 1 in the Federal 
Register notice of the proposed IHA has been corrected in this Federal 
Register notice. Specifically, the number of estimated days of 
installation and removal of 24-inch steel piles included in the Table 
was incorrect. No other changes have been made from the proposed IHA to 
the final IHA.

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the DOT&PF's 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, referenced here, instead of 
reprinting the information. Additional information regarding population 
trends and threats may be found in NMFS' Stock Assessment Reports 
(SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these 
species (e.g., physical and behavioral descriptions) may be found on 
NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
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 expected to occur, 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.
    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 stocks managed under the MMPA in this region 
are assessed in NMFS' U.S. Alaska and Pacific SARs (e.g., Carretta, et 
al., 2023; Young et al., 2023). All values presented in Table 2 are the 
most recent available at the time of publication and are available 
online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                            Table 2--Species \4\ Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/MMPA status;   Stock  abundance  (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Humpback Whale..................  Megaptera novaeangliae.  Hawaii.................  -, -, N             11,278 (0.56, 7,265,          127      27.09
                                                                                                             2020).
                                                               Mexico-North Pacific...  T, D, Y             918 (0.217, UNK, 2006)        UND       0.57
    Minke Whale.....................  Balaenoptera             Alaska.................  -, -, N             N/A (N/A, N/A, N/A)...        UND          0
                                       acutorostrata.
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 1069]]

 
                                                  Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer Whale....................  Orcinus orca...........  Eastern North Pacific    -, -, N             1,920 (N/A, 1,920,             19        1.3
                                                                Alaska Resident.                             2019).
    Killer Whale....................  Orcinus orca...........  Eastern Northern         -, -, N             302 (N/A, 302, 2018)..        2.2        0.2
                                                                Pacific Northern
                                                                Resident.
    Killer Whale....................  Orcinus orca...........  West Coast Transient...  -, -, N             349 (N/A, 349, 2018)..        3.5        0.4
    Pacific White-Sided Dolphin.....  Lagenorhynchus           N Pacific..............  -, -, N             26,880 (N/A, N/A,             UND          0
                                       obliquidens.                                                          1990).
Family Phocoenidae (porpoises):
    Dall's Porpoise.................  Phocoenoides dalli.....  Alaska.................  -, -, N             UND (UND, UND, 2015)..        UND         37
Harbor Porpoise.....................  Phocoena phocoena......  Southern Southeast       -, -, Y             890 (0.37, 610, 2019).        6.1        7.4
                                                                Alaska Inland Waters.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
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):
    Harbor Seal.....................  Phoca vitulina.........  Dixon/Cape Decision....  -, -, N             23,478 (N/A, 21,453,          644         69
                                                                                                             2015).
    Northern Elephant Seal..........  Mirounga angustirostris  CA Breeding............  -, -, N             187,386 (N/A, 85,369,       5,122       13.7
                                                                                                             2013).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 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.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region/. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N/
  A).
\3\ 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 human caused mortality and serious injury (M/SI) often cannot be determined precisely and is in some cases
  presented as a minimum value or range.
\4\ 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)).

    A detailed description of the species likely to be affected by the 
construction project, including a brief introduction to the affected 
stock as well as available information regarding population trends and 
threats, and information regarding local occurrence, were provided in 
the Federal Register notice for the proposed IHA (88 FR 41920, June 28, 
2023). Since that time, the structure of the harbor porpoise and 
humpback whale stocks have been updated; therefore, a detailed 
description of those species updated stock structure is provided here. 
Please refer to the Federal Register notice of the proposed IHA (88 FR 
41920, June 28, 2023) for the full description for all species. Please 
also refer to NMFS' website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts.

Harbor Porpoise

    In the 2022 Alaska SAR, stock structure was revised for the 
Southeast Alaska harbor porpoise stock, which was split into three 
stocks: 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 Hydaburg are assumed to be members of 
the Southern Southeast Alaska Inland Waters stock based on the 
geographical range of the stock, which encompasses Sumner Strait, 
including areas around Wrangell and Zarembo Islands, Clarence Strait, 
and adjacent inlets and channels within the inland waters of Southeast 
Alaska north-northeast of Dixon Entrance.

Humpback Whale

    The 2022 Alaska and Pacific SARs include an update to the humpback 
whale stock structure which modifies the previously MMPA-designated 
humpback stocks to align more closely with the ESA-designated distinct 
population segments (DPSs) (Caretta et al., 2023; Young et al., 2023). 
Specifically, the three existing 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 (Carretta et al., 2023; Young et al., 2023). In the 
notice of the proposed IHA, NMFS assumed that humpbacks in the proposed 
action area were members of the Central North Pacific Stock. Based on 
these new delineations, humpback whales in the proposed action area are 
now assumed to be members of either the Hawaii stock or the Mexico-
North Pacific stock.
    The Hawaii stock consists of one demographically independent 
population (DIP) (Hawaii-Southeast Alaska/Northern British Columbia 
DIP) and the Hawaii-North Pacific unit, which may or may not be 
composed of multiple DIPs (Wade et al., 2021). The DIP and unit are 
managed as a single stock at this time, due to the lack of data 
available to separately assess them and lack of compelling conservation 
benefit to managing them separately (NMFS, 2019; NMFS, 2022b; NMFS 
2023). The

[[Page 1070]]

DIP is delineated based on two strong lines of evidence: genetics and 
movement data (Wade et al., 2021). Whales in the Hawaii-Southeast 
Alaska/Northern British Columbia DIP winter off Hawaii and largely 
summer in Southeast Alaska and Northern British Columbia (Wade et al., 
2021). The group of whales that migrate from Russia, western Alaska 
(Bering Sea and Aleutian Islands), and central Alaska (Gulf of Alaska 
excluding Southeast Alaska) to Hawaii have been delineated as the 
Hawaii-North Pacific unit (Wade et al., 2021). There are a small number 
of whales that migrate between Hawaii and southern British Columbia/
Washington, but current data and analyses do not provide a clear 
understanding of which unit these whales belong to (Wade et al., 2021; 
Caretta et al., 2023; Young et al., 2023)
    The Hawaii stock of humpback whales is equivalent to the Hawaii DPS 
of humpback whales, which is not listed under the ESA (Bettridge et 
al., 2015; Wade et al., 2021). Humpback whales were previously 
considered to be depleted species-wide under the MMPA solely on the 
basis of the species' ESA listing. After the evaluation of the listing 
status of DPSs of humpback whales, humpback whale DPSs that are not 
listed as threatened or endangered were not considered to have depleted 
status under the MMPA (81 FR 62259, September 8, 2016). However, 
because the Central North Pacific stock, which is what humpback whales 
in Hydaburg were presumed to be members of in the notice of the 
proposed IHA, included some whales from the ESA-listed Mexico and 
Western North Pacific DPSs, the stock was considered to be endangered 
and depleted, and as a result, was classified as a strategic stock. The 
newly defined Hawaii stock of humpback whales does not include whales 
from any listed DPSs and, therefore, is not currently considered 
depleted under the MMPA, and is also not a strategic stock due to its 
ESA status.
    The Mexico-North Pacific unit is likely composed of multiple DIPs, 
based on movement data (Martien et al., 2021; Wade, 2021, Wade et al., 
2021). However, because currently available data and analyses are not 
sufficient to delineate or assess DIPs within the unit, it was 
designated as a single stock (NMFS, 2019; NMFS, 2022c; NMFS, 2023a). 
Whales in this stock winter off Mexico and the Revillagigedo 
Archipelago and summer primarily in Alaska waters (Martien et al., 
2021) (Carretta et al., 2023; Young et al., 2023). The Mexico-North 
Pacific stock of humpback whales is one of two stocks that make up the 
``Mexico DPS'' of humpback whales, which are listed as threatened under 
the ESA (Bettridge et al. 2015; Martien et al., 2021), and is therefore 
considered ``depleted'' and ``strategic'' under the MMPA.

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 or hear over the same frequency range (e.g., 
Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 
2008). To reflect this, Southall et al. (2007, 2019) recommended that 
marine mammals be divided into hearing groups based on directly 
measured (behavioral or auditory evoked potential techniques) or 
estimated hearing ranges (behavioral response data, anatomical 
modeling, etc.). Note that no direct measurements of hearing ability 
have been successfully completed for mysticetes (i.e., low-frequency 
cetaceans). Subsequently, NMFS (2018) described generalized hearing 
ranges for these marine mammal hearing groups. Generalized hearing 
ranges were chosen based on the approximately 65 decibel (dB) threshold 
from the normalized composite audiograms, with the exception for lower 
limits for low-frequency cetaceans where the lower bound was deemed to 
be biologically implausible and the lower bound from Southall et al. 
(2007) retained. Marine mammal hearing groups and their associated 
hearing ranges are provided in Table 3.

                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true    275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al., 2007) and PW pinniped (approximation).

    The pinniped 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 et al., 2013).
    For more detail concerning these groups and associated generalized 
hearing ranges, please see NMFS (2018) for a review of available 
information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The underwater noise produced by the DOT&PF's construction 
activities has the potential to result in behavioral harassment of 
marine mammals in the vicinity of the survey area. The Federal Register 
notice of the proposed IHA (88 FR 45774, July 17, 2023) included a 
discussion of the effects of anthropogenic noise on marine mammals and 
the potential effects of underwater noise from the DOT&PF' construction 
activities on marine mammals and their habitat. That information and 
analysis is incorporated by reference into this final IHA determination 
and is not repeated here; please refer to the notice of the proposed 
IHA (88 FR 45774, July 17, 2023).

[[Page 1071]]

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized through the IHA, which will inform both NMFS' consideration 
of ``small numbers,'' and the negligible impact determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes will primarily be by Level B harassment, as use of 
the acoustic source (i.e., vibratory pile driving, impact pile driving, 
and DTH systems) has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory (Level A harassment) to result, primarily for 
mysticetes and high frequency species and phocids because predicted 
auditory injury zones are larger than for mid-frequency species and 
otariids. Auditory injury is unlikely to occur for mid-frequency 
species or otariids. 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 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., seismic 
airguns) or intermittent (e.g., scientific sonar) sources. Generally 
speaking, Level B harassment take estimates based on these behavioral 
harassment thresholds are expected to include any likely takes by TTS 
as, in most cases, the likelihood of TTS occurs at distances from the 
source less than those at which behavioral harassment is likely. TTS of 
a sufficient degree can manifest as behavioral harassment, as reduced 
hearing sensitivity and the potential reduced opportunities to detect 
important signals (conspecific communication, predators, prey) may 
result in changes in behavior patterns that would not otherwise occur.
    The DOT&PF's activity includes the use of continuous (vibratory 
pile driving) and intermittent (impact pile driving) sources, and 
therefore the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are 
applicable. DTH systems have both continuous, non-impulsive, and 
impulsive components. When evaluating Level B harassment, NMFS 
recommends treating DTH as a continuous source and applying the RMS SPL 
thresholds of 120 dB re 1 [mu]Pa.
    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). The 
DOT&PF's construction includes the use of impulsive (impact pile 
driving) and non-impulsive (vibratory pile driving) sources. As 
described above, DTH includes both impulsive and non-impulsive 
characteristics. When evaluating Level A harassment, NMFS recommends 
treating DTH as an impulsive source.
    The thresholds used to identify the onset of PTS are provided in 
Table 4. The references, analysis, and methodology used in the 
development of the thresholds are described in NMFS' 2018 Technical 
Guidance, which may be accessed at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.

[[Page 1072]]

 
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for NMFS' 2018 Technical Guidance. Hence, the subscript ``flat''
  is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

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 project. Marine 
mammals are expected to be affected via sound generated by the primary 
components of the project (i.e., impact pile installation, vibratory 
pile installation, vibratory pile removal, and DTH).
    Sound Source Levels of Construction Activities--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 
(Table 5). A description of the assessment and appropriateness of proxy 
sound source levels and TL measurements for the DOT&PF's activities can 
be found in the notice of proposed IHA (88 FR 45774, July 17, 2023). 
This includes a discussion regarding the analyses of noise from DTH 
systems that follows NMFS' recommendations (i.e., https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf; NMFS, 2022a). 
Please refer to the notice of the proposed IHA (88 FR 45774, July 17, 
2023) for full details.

                                           Table 5--Summary of Unattenuated In-Water Pile Driving Proxy Levels
                                                                        [At 10 m]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          Peak SPL (dB   RMS SPL (dB re    SELss (dB re 1
                Pile type                       Installation method       re 1 [mu]Pa)      1 [mu]Pa)      [mu]Pa\2\ sec)         Reference (levels)
--------------------------------------------------------------------------------------------------------------------------------------------------------
16-inch steel piles......................  Vibratory hammer............              NA             158                  NA  CALTRANS (2020).
20-inch steel piles......................  Vibratory hammer............              NA             161                  NA  Navy (2015).
24-inch steel piles......................  Vibratory hammer............              NA             161                  NA  Navy (2015).
20-inch steel piles......................  Impact hammer...............             208             187                 176  CALTRANS (2020).
24-inch steel piles......................  Impact hammer...............             208             193                 178  CALTRANS (2020).
8-inch tension anchors...................  DTH system..................             170             156                 144  Reyff and Heyvaert (2019);
                                                                                                                              Reyff (2020).
20-inch rock sockets.....................  DTH system..................             184             167                 159  Heyvaert and Reyff (2021).
24-inch rock sockets.....................  DTH system..................             184             167                 159  Heyvaert and Reyff (2021).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: NMFS conservatively assumes that noise levels during vibratory pile removal are the same as those during installation for the same type and size
  pile; all SPLs are unattenuated and represent the SPL referenced at a distance of 10 m from the source; NA = Not applicable; dB re 1 [mu]Pa = decibels
  (dB) referenced to a pressure of 1 micropascal.

    Estimated Harassment Isopleths--All Level B harassment isopleths 
are reported in Table 7 considering RMS SPLs and the default TL 
coefficient for practical spreading loss (i.e., 15*Log10(range)). Land 
forms (including causeways, breakwaters, islands, and other land 
masses) impede the transmission of underwater sound and create shadows 
behind them where sound from construction is not audible. At Hydaburg, 
Level B harassment isopleths from the project will be blocked by 
Sukkwan Island, Spook Island, Mushroom Island, and the coastline along 
Prince of Wales Island both southeast and northwest of the project 
site. The maximum distance that a harassment isopleth can extend due to 
these land masses is 5,162 m.
    The ensonified area associated with Level A harassment is 
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 (2018) 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 from impact pile driving, vibratory pile 
driving, and DTH), the optional User Spreadsheet tool predicts the 
distance at which, if a marine mammal remained at that distance for the 
duration of the activity, it would be expected to incur PTS. Inputs 
used in the optional User

[[Page 1073]]

Spreadsheet tool are reported in Table 6 and the resulting estimated 
isopleths are reported in Table 7.

                                                                              Table 6--NMFS User Spreadsheet Inputs
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Vibratory pile driving                                        Impact pile driving                             DTH
                                 ---------------------------------------------------------------------------------------------------------------------------------------------------------------
                                     16-inch steel       20-inch steel              24-inch steel piles              20-inch steel       24-inch steel      20- and 24-inch     8-inch tension
                                         piles               piles       ----------------------------------------        piles               piles            rock socket           anchor
                                 ----------------------------------------                                        -------------------------------------------------------------------------------
                                                         Installation/       Installation           Removal
                                        Removal             removal                                                  Installation        Installation        Installation        Installation
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used............  A.1) Non-Impul,     A.1) Non-Impul,     A.1) Non-Impul,     A.1) Non-Impul,     E.1) Impact pile    E.1) Impact pile    E.2) DTH Systems..  A.1) DTH Systems.
                                   Stat, Cont.         Stat, Cont.         Stat, Cont.         Stat, Cont.         driving.            driving.
Source Level (SPL)..............  158 dB RMS........  161 dB RMS........  161 dB RMS........  161 dB RMS........  176 dB SEL........  178 dB SEL........  159 dB RMS........  144 dB RMS.
Transmission Loss Coefficient...  15................  15................  15................  15................  15................  15................  15................  15.
Weighting Factor Adjustment       2.5...............  2.5...............  2.5...............  2.5...............  2.................  2.................  2.................  2.
 (kHz).
Time to install/remove single     30................  15/30 \1\.........  15/30 \1\.........  30................  ..................  ..................  60-480 \2\........  60-240.\2\
 pile (minutes).
Number of strikes per pile......  ..................  ..................  ..................  ..................  50................  50................  15................  15.
Piles per day...................  2.................  2/10 \1\..........  2/10 \1\..........  2.................  1/2 \1\...........  1/2 \1\...........  1.................  1.
Distance of sound pressure level  10................  10................  10................  10................  10................  10................  10................  10.
 measurement (m).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A maximum scenario was calculated for this activity.
\2\ A range of scenarios was calculated for this activity.


   Table 7--Distances to Level A Harassment, by Hearing Group, and Distances and Areas of Level B Harassment Thresholds per Pile Type and Pile Driving
                                                                         Method
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Level A harassment distance (m)       Level B      Level B
                                                                                       ----------------------------------------  harassment   harassment
                                                        Minutes (min) or    Piles per                                             distance       area
            Activity                   Pile size        strikes per pile       day                                                (m) all    (km\2\) all
                                                                                          LF      MF      HF      PW      OW      hearing      hearing
                                                                                                                                   groups       groups
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation..........  20- and 24-inch....  15 min............            2       5       1       7       3       1    \3\ 5,412     \4\ 4.34
                                                       30 \1\ min........       \1\ 10      20       2      30      13       1
Vibratory Removal...............  16-inch............  30 min............            2       5       1       7       3       1        3,415         3.90
                                  24-inch............  30 min............            2       7       1      11       5       1    \3\ 5,412     \4\ 4.34
Impact Installation.............  20-inch............  50 strikes........            1      47       2      56      25       2        1,585         2.14
                                                       50 \1\ strikes....        \1\ 2      74       3      88      40       3
                                  24-inch............  50 strikes........            1      63       3      75      34       3          631         0.65
                                                       50 \1\ strikes....        \1\ 2     100       4     119      54       4
DTH (Rock Socket) \2\...........  20- and 24-inch....  60 min............            1     359      13     427     192      14   \3\ 13,594     \4\ 4.34
                                                       120 min...........            1     569      21     678     305      23
                                                       80 min............            1     746      27     888     399      29
                                                       240 min...........            1     903      33   1,076     484      36
                                                       300 min...........            1   1,048      38   1,249     561      41
                                                       360 min...........            1   1,184      43   1,410     634      47
                                                       420 min...........            1   1,312      47   1,563     702      52
                                                       480 min...........            1   1,434      51   1,708     768      56
DTH (Tension Anchor) \2\........  8-inch.............  60 min............            1      36       2      43      20       2        2,512         3.07
                                                       120 min...........            1      57       2      68      31       3
                                                       180 min...........            1      75       3      89      40       3
                                                       240 min...........            1      91       4     108       4       4
                                                       300 min...........            1     105       4     125      57       5
                                                       360 min...........            1     119       5     141      64       5
                                                       420 min...........            1     132       5     157      71       6
                                                       480 min...........            1     144       6     171      77       6
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A maximum scenario was calculated for this activity.
\2\ A range of scenarios was calculated for this activity.
\3\ Harassment distances will be truncated where appropriate to account for land masses, to a maximum distance of 5,162 m.
\4\ Harassment areas are truncated where appropriate to account for land masses, to a maximum area of 4.34 km\2\.


[[Page 1074]]

Marine Mammal Occurrence and Take Estimation

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information that 
will inform the take calculations. We also describe how this 
information is synthesized to produce a quantitative estimate of the 
take that is reasonably likely to occur and is authorized. Although 
construction is currently planned to begin in fall 2023, unexpected 
delays associated with construction can occur. To account for this 
uncertainty, the following exposure estimates assume that construction 
will occur during the periods of peak abundance for those species for 
which abundance varies seasonally.

Steller Sea Lion

    No density or abundance numbers exist for Steller sea lions in the 
action area, and they are not known to regularly occur near Hydaburg. 
However, in context of a lack of local data, the DOT&PF conservatively 
estimated that during peak salmon runs, 6 groups of 10 individuals 
could be exposed to project-related underwater noise each week during 
pile installation and removal activities, for a total of 240 exposures 
(4 weeks * 60 sea lions per week = 240 total exposures).
    The largest Level A harassment zone for Steller sea lions is 59 m 
(Table 7). Due to the small Level A harassment zones (Table 7) and the 
implementation of shutdown zones, which will be larger than Level A 
harassment zones (described below in the Mitigation section), NMFS has 
determined that take by Level A harassment is not anticipated for 
Steller sea lions. Therefore, NMFS authorizes all 240 estimated 
exposures as takes by Level B harassment. Takes by Level A harassment 
for Steller sea lions are not authorized.

Harbor Seal

    Up to six known harbor seal haulouts are located near the project 
area; however, they are all located outside of the estimated harassment 
zones, with the closest haulout located just over 4.5 km southeast of 
the project site, but blocked by a land shadow (see Figure 4-2 in the 
DOT&PF's application). Within the project area, harbor seals remain 
relatively rare as described by local residents. The DOT&PF 
conservatively estimated that up to 8 harbor seals could be within 
estimated harassment zones each day during pile installation and 
removal activities, for a total of 208 exposures (26 days * 8 seals per 
day = 208 total exposures).
    The largest Level A harassment zone for harbor seals is 768 m 
(Table 7). There are no known harbor seal haulouts within this 
distance, however, it is possible that harbor seals may approach and 
enter within this distance for sufficient duration to incur PTS. 
Further, the largest practicable shutdown zone that the DOT&PF can 
implement for harbor seals is 400 m (described below in the Mitigation 
section). To account for this difference, NMFS authorizes additional 
takes by Level A harassment, as compared with the DOT&PF's request of 
48 takes by Level A harassment, which assumed smaller Level A 
harassment isopleths based on their assessment of DTH systems. 
Additional takes were determined by calculating the ratio of the 
largest Level A harassment area for 20- and 24-inch (50.8- and 60.96-
cm) DTH activities (i.e., 0.89 km\2\ for a Level A harassment distance 
of 768 m) minus the area of the shutdown zone for harbor seals (i.e., 
0.27 km\2\ for a shutdown zone distance of 400 m) to the area of the 
Level B harassment isopleth (4.34 km\2\ for a Level B harassment 
distance of 5,162 m) (i.e., (0.89 km\2\-0.27 km\2\)/4.34 km\2\ = 0.14). 
We then multiplied this ratio by the total number of estimated harbor 
seal exposures to determine additional take by Level A harassment 
(i.e., 0.14 * 208 exposures = 29.12 takes, rounded up to 30 takes). The 
total take by Level A harassment was then calculated as the take 
originally requested by the DOT&PF plus the additional take calculated 
by NMFS (i.e., 48 + 30), for a total of 78 takes by Level A harassment. 
Takes by Level B harassment were calculated as the number of estimated 
harbor seal exposures minus the amount of take by Level A harassment 
(i.e., 208-78). Therefore, NMFS authorizes 78 takes by Level A 
harassment and 130 takes by Level B harassment for harbor seals, for a 
total of 208 takes.

Northern Elephant Seal

    Northern elephant seal abundance throughout coastal southeast 
Alaska is low, and anecdotal reports have not included northern 
elephant seals near the project area. However, northern elephant seals 
have been observed elsewhere in southeast Alaska; therefore, this 
species could occur near the project area. To account for this 
possibility, the DOT&PF estimated that one northern elephant seal could 
be within estimated harassment zones each week during pile installation 
and removal activities, for a total of four exposures (4 weeks * 1 
northern elephant seal each week = 4 total exposures).
    The largest practicable shutdown zone the DOT&PF can implement for 
northern elephant seals (400 m) (described below in the Mitigation 
section) is smaller than the Level A harassment isopleths that result 
from 240 or minutes more of 20- and 24-inch (50.8- and 60.96-cm) DTH 
rock socket installation (Table 7). To account for this difference, 
NMFS followed the same method as described above for harbor seals to 
calculate take by Level A harassment for northern elephant seals. This 
was achieved by calculating the ratio of the largest Level A harassment 
area for 20- and 24-inch (50.8- and 60.96-cm) DTH activities (i.e., 
0.89 km\2\ for a Level A harassment distance of 768 m) minus the area 
of the shutdown zone for elephant seals (i.e., 0.27 km\2\ for a 
shutdown zone distance of 400 m) to the area of the Level B harassment 
isopleth (4.34 km\2\ for a Level B harassment distance of 5,162 m) 
(i.e., (0.89 km\2\-0.27 km\2\)/4.34 km\2\ = 0.14), and by multiplying 
this ratio by the total number of estimated northern elephant seal 
exposures (i.e., 0.14 * 4 exposures = 0.56 takes, rounded up to 1 take 
by Level A harassment). Takes by Level B harassment were calculated as 
the number of estimated northern elephant exposures minus the amount of 
authorized take by Level A harassment (i.e., 4-1). Therefore, NMFS 
authorizes one take by Level A harassment and three takes by Level B 
harassment for northern elephant seals, for a total of four takes.

Harbor Porpoise

    There have been no systematic studies or observations of harbor 
porpoises specific to Hydaburg or Sukkwan Strait, and sightings of 
harbor porpoises have not been described in this region by local 
residents. As such, there is limited potential for them to occur in the 
project area, but they could occur in low numbers as individuals have 
been observed in southern inland waters of southeast Alaska. Therefore, 
the DOT&PF estimated that up to two harbor porpoises could be within 
estimated harassment zones each day during pile installation and 
removal activities, for a total of 52 exposures (26 days * 2 porpoises 
per day = 52 exposures).
    Harbor porpoises are small, lack a visible blow, have low dorsal 
fins, an overall low profile, and a short surfacing time, making them 
difficult to observe (Dahlheim et al., 2015). These characteristics 
likely reduce the identification and reporting of this species. For 
these reasons, and based off

[[Page 1075]]

of their assessment of DTH systems, the DOT&PF requested that eight 
takes by Level A harassment be authorized for harbor porpoises (4 weeks 
* 2 harbor porpoise per week = 8 takes by Level A harassment).
    The maximum Level A harassment isopleth estimated by NMFS for 
harbor porpoises is 1,708 m, which is larger than what the DOT&PF 
analyzed. The largest practicable shutdown zone that the DOT&PF can 
implement for harbor porpoises is 500 m (described below in the 
Mitigation section). To account for this difference and the increased 
possibility of harbor porpoises occurring outside of the shutdown zone 
and in the Level A harassment zone long enough to incur PTS, NMFS 
authorizes additional takes by Level A harassment, as compared with the 
DOT&PF's request. Additional takes were determined by calculating the 
ratio of the largest Level A harassment area for 20- and 24-inch (50.8- 
and 60.96-cm) DTH activities (i.e., 2.25 km\2\ for a Level A harassment 
distance of 1,708 m minus the area of the shutdown zone for harbor 
porpoises (i.e., 0.42 km\2\ for a shutdown zone distance of 500 m) to 
the area of the Level B harassment isopleth (4.34 km\2\ for a Level B 
harassment distance of 5,162 m) (i.e., (2.25 km\2\-0.42 km\2\)/4.34 
km\2\ = 0.42). We then multiplied this ratio by the total number of 
estimated harbor porpoise exposures to determine additional take by 
Level A harassment (i.e., 0.42 * 8 exposures = 3.36 takes, rounded up 
to 4 takes). The total take by Level A harassment was then calculated 
as the take originally requested by the DOT&PF plus the additional take 
calculated by NMFS (i.e., 8 + 4), for a total of 12 takes by Level A 
harassment. Takes by Level B harassment were calculated as the number 
of estimated harbor porpoise exposures minus the amount of take by 
Level A harassment (i.e., 52-12). Therefore, NMFS authorizes 12 takes 
by Level A harassment and 40 takes by Level B harassment for harbor 
seals, for a total of 52 takes.

Dall's Porpoise

    Dall's porpoises are not expected to occur in Sukkwan Strait 
because the shallow water habitat of the bay is atypical of areas where 
Dall's porpoises usually occur. However, recent research indicates that 
Dall's porpoises may opportunistically exploit nearshore habitats where 
predators, such as killer whales, are absent. Therefore, the DOT&PF 
anticipates that one large Dall's porpoise pod (15 individuals) could 
be within the estimated harassment zones during in-water construction, 
for a total of 15 possible exposures.
    Dall's porpoises typically appear in larger groups and exhibit 
behaviors that make them more visible and thus easier to observe at 
distance. Based on this assumption, the DOT&PF did not request any 
takes by Level A harassment for this species. However, the maximum 
Level A harassment zone is 1,708 m, which is larger than what the 
DOT&PF analyzed. The largest practicable shutdown zone that the DOT&PF 
can implement for Dall's porpoises during this project is 500 m 
(described below in the Mitigation section). To account for this 
difference and the increased possibility of Dall's porpoises occurring 
outside of the shutdown zone and in the Level A harassment zones for 
sufficient duration to incur PTS, NMFS adds takes by Level A 
harassment, as compared with the DOT&PF's request. Because Dall's 
porpoises typically occur in groups, NMFS authorizes 15 takes (i.e., 
one large pod) by Level A harassment in addition to the 15 takes by 
Level B harassment that the DOT&PF requested, for a total of 30 takes. 
This will help to ensure that the DOT&PF have enough takes to account 
for the possibility of one large pod occurring in either the Level A or 
the Level B harassment zone.

Pacific White-Sided Dolphin

    Pacific white-sided dolphins do not generally occur in the shallow, 
inland waterways of southeast Alaska. There are no records of this 
species occurring in Sukkwan Strait, and it is uncommon for individuals 
to occur in the project area. However, recent fluctuations in 
distribution and abundance decrease the certainty in this prediction. 
Therefore, the DOT&PF conservatively estimated that one large group (92 
individuals) of Pacific white-sided dolphins could be within estimated 
harassment zones during the in-water construction.
    The largest Level A harassment zone estimated by NMFS for Pacific 
white-sided dolphins is 51 m. Due to the small Level A harassment zones 
(Table 7) and the implementation of shutdown zones, which will be 
larger than Level A harassment zones (described below in the Mitigation 
section), take by Level A harassment is not anticipated for Pacific 
white-sided dolphins. Therefore, NMFS authorizes all 92 estimated 
exposures as takes by Level B harassment. Takes by Level A harassment 
for Pacific white-sided dolphins are not authorized.

Killer Whale

    Killer whales are observed infrequently throughout Sukkwan Strait, 
and their presence near Hydaburg is unlikely. However, anecdotal local 
information suggests that a pod may be seen in the project area every 
few months. Therefore, the DOT&PF estimate that one killer whale pod of 
up to 15 individuals may be within estimated harassment zones once 
during the pile installation and removal activities (15 total 
exposures).
    The largest Level A harassment zone for killer whales is 51 m 
(Table 7). Because killer whales are unlikely to enter Sukkwan Strait 
and are relatively conspicuous, it is unlikely they will approach this 
distance for sufficient duration to incur PTS. Due to the small Level A 
harassment zones (Table 7) and the implementation of shutdown zones, 
which will be larger than Level A harassment zones (described below in 
the Mitigation section), take by Level A harassment is not anticipated 
for killer whales. Therefore, NMFS authorizes all 15 estimated 
exposures as takes by Level B harassment. Takes by Level A harassment 
for killer whales are not authorized.

Humpback Whale

    Use of Sukkwan Strait by humpback whales is common but intermittent 
and dependent on the presence of prey fish. Based on anecdotal evidence 
from local residents, the DOT&PF predicts that four groups of two 
whales, up to eight individuals per week, may be within estimated 
harassment zones each week during the 4 weeks of the pile installation 
and removal activities, for a total of 32 exposures (8 per week * 4 
weeks = 32 total exposures). Wade (2021) estimated that approximately 
2.4 percent of humpback whales in southeast Alaska are members of the 
Mexico-North Pacific stock, while all others are members of the Hawaii 
stock. Therefore, the DOT&PF estimates that 1 of the exposures (32 
whales * 0.024 = 0.77 rounded up to 1) will be of an individual from 
the Mexico stock individuals and 31 exposures will be of individuals 
from the Hawaii stock.
    Due to the long duration of DTH piling that is anticipated, and the 
potential for humpback whales to enter the Level A harassment zones 
from around obstructions or landforms near the project area, the DOT&PF 
requested that NMFS authorize 4 takes by Level A harassment (equivalent 
to two groups of two individuals) of humpback whales. Due to the small 
percentage of humpback whales that may belong to the Mexico-North 
Pacific stock in southeast Alaska, the DOT&PF assumes that all takes by 
Level A harassment will be attributed to Hawaii DPS whales.
    The largest Level A harassment zone for humpback whales is 1,435 m 
(Table 7), which is larger than what the

[[Page 1076]]

DOT&PF analyzed. The largest practicable shutdown zone that the DOT&PF 
can implement for humpback whales during this project is 1,000 m 
(described below in the Mitigation section). To account for this 
difference and the increased possibility of humpback whales occurring 
outside of the shutdown zone and in the Level A harassment zone long 
enough to incur PTS, NMFS added additional takes by Level A harassment, 
compared with the DOT&PF's request.
    NMFS calculated additional takes by Level A harassment by 
determining the ratio of the largest Level A harassment area for 20- 
and 24-inch (50.8- and 60.96-cm) DTH activities (i.e., 2.01 km\2\ for a 
Level A harassment distance of 1,435 m) minus the area of the shutdown 
zone for humpback whales (i.e., 1.34 km\2\ for a shutdown zone distance 
of 1,000 m) to the area of the Level B harassment isopleth (4.34 km\2\ 
for a Level B harassment distance of 5,162 m) (i.e., (2.01 km\2\-1.34 
km\2\)/4.34 km\2\ = 0.15). We then multiplied this ratio by the total 
number of estimated humpback whales exposures to determine additional 
take by Level A harassment (i.e., 0.15 * 32 exposures = 4.80 takes, 
rounded up to 5 takes). The total take by Level A harassment was then 
calculated as the take originally requested by the DOT&PF plus the 
additional take calculated by NMFS (i.e., 4 + 5), for a total of 9 
takes by Level A harassment. Takes by Level B harassment were 
calculated as the number of estimated humpback whale exposures minus 
the amount of take by Level A harassment (i.e., 32-9). Therefore, NMFS 
authorizes 9 takes by Level A harassment and 23 takes by Level B 
harassment for humpback whales, for a total of 32 takes. Given that 
approximately 2.4 percent of humpback whales in southeast Alaska are 
members of the Mexico-North Pacific stock, NMFS assumes that one of the 
takes by Level B harassment may be attributed to a humpback whale from 
the Mexico-North Pacific stock (32 * 2.4 percent = 0.77, rounded up to 
1 take). All other takes by Level B harassment and all takes by Level A 
harassment (i.e., 31) are assumed to be attributed to humpback whales 
from the Hawaii stock.

Minke Whale

    Minke whale abundance throughout southeast Alaska is low, and 
anecdotal reports have not included minke whales near the project area. 
However, minke whales are distributed throughout a wide variety of 
habitats and have been observed elsewhere in southeast Alaska; 
therefore, this species could occur near the project area. NMFS has 
previously estimated that three individual minke whales could occur 
near Metlakatla every 4 months during a similar activity (86 FR 43190, 
August 6, 2021). Therefore, DOT&PF conservatively estimated that up to 
three minke whales may be exposed to project-related underwater noise 
during the pile installation and removal activities.
    Due to the low likelihood of minke whale occurrence near the 
project site, the DOT&PF did not request any takes by Level A 
harassment for this species. However, the maximum Level A harassment 
isopleth estimated by NMFS for minke whales is 1,435 m, which is larger 
than what the DOT&PF analyzed. The largest practicable shutdown zone 
that the DOT&PF can implement for minke whales during this project is 
1,000 m (described below in the Mitigation section). To account for 
this difference and the increased possibility of minke whales occurring 
outside of the shutdown zone and within the Level A harassment zone 
long enough to incur PTS, NMFS added takes by Level A harassment to the 
DOT&PF's request.
    NMFS calculated additional takes by Level A harassment by 
determining the ratio of the largest Level A harassment area for 20- 
and 24-inch (50.8- and 60.69-cm) DTH activities (i.e., 2.01 km\2\ for a 
Level A harassment distance of 1,435 m) minus the area of the shutdown 
zone for minke whales (i.e., 1.34 km\2\ for a shutdown zone distance of 
1,000 m) to the area of the Level B harassment isopleth (4.34 km\2\) 
for a Level B harassment distance of 5,162 m) (i.e., (2.01 km\2\-1.34 
km\2\)/4.34 km\2\ = 0.15). We then multiplied this ratio by the total 
number of estimated minke whales exposures to determine take by Level A 
harassment (i.e., 0.15 * 3 exposures = 0.45 takes, rounded up to 1 take 
by Level A harassment). Takes by Level B harassment were calculated as 
the number of estimated minke whale exposures minus the amount of take 
by Level A harassment (i.e., 3-1). Therefore, NMFS authorizes one take 
by Level A harassment and two takes by Level B harassment for minke 
whales, for a total of three takes.
    In summary, the total amount of takes by Level A harassment and 
Level B harassment authorized for each marine mammal stock is presented 
in Table 8.

       Table 8--Amount of Authorized Take as a Percentage of Stock Abundance, by Stock and Harassment Type
----------------------------------------------------------------------------------------------------------------
                                                                  Authorized take
            Species               Stock or DPS   ------------------------------------------------   Percent  of
                                                      Level A         Level B          Total           stock
----------------------------------------------------------------------------------------------------------------
Steller sea lion..............  Eastern.........               0             240             240            0.56
Harbor seals..................  Dixon/Cape                    78             130             208            0.89
                                 Decision.
Northern elephant seals.......  CA Breeding.....               1               3               4           <0.01
Harbor porpoises..............  Southern                      12              40              52            5.84
                                 Southeast
                                 Alaska Inland
                                 Waters.
Dall's porpoises..............  Alaska..........              15              15              30         \1\ UNK
Pacific white-sided dolphins..  N Pacific.......               0              92              92            0.34
Killer whales.................  Eastern North                  0              15              15        \2\ 0.78
                                 Pacific Alaska
                                 Resident.
                                Eastern Northern                                                        \2\ 4.97
                                 Pacific
                                 Northern
                                 Resident.
                                West Coast                                                              \3\ 4.30
                                 Transient.
Humpback whales...............  Hawaii..........               9              23              32        \2\ 0.28
                                Mexico-North                                                             1 2 UNK
                                 Pacific.
Minke whales..................  Alaska..........               1               2               3  ..............
----------------------------------------------------------------------------------------------------------------
\1\ NMFS does not have an official abundance estimate for this stock; please refer to the Small Numbers section
  of this notice for a discussion regarding the percentage of this stock authorized for take.
\2\ NMFS conservatively assumes that all takes occur to each stock.


[[Page 1077]]

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 (latter not applicable for this action). 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 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.
    The DOT&PF must employ the following standard mitigation measures, 
as included in the IHA:
     Ensure that construction supervisors and crews, the 
monitoring team and relevant DOT&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;
     Avoid direct physical interaction with marine mammals 
during construction activity. If a marine mammal comes within 10 m of 
such activity, operations shall cease. Should a marine mammal come 
within 10 m of a vessel in transit, the boat operator will reduce 
vessel speed to the minimum level required to maintain steerage and 
safe working conditions. If human safety is at risk, the in-water 
activity will be allowed to continue until it is safe to stop;
     Employ PSOs and establish monitoring locations as 
described in Section 5 of the IHA. The DOT&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 pile driving and DTH activities at least two PSOs must be used;
     For all pile driving/removal activities, a minimum 30 m 
shutdown zone must be established. 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 will vary based on the type 
of driving/removal activity type and by marine mammal hearing group 
(see Table 9). Here, shutdown zones are larger than or equivalent to 
the calculated Level A harassment isopleths shown in Table 7, except 
when indicated due to practicability and effectiveness concerns. These 
concerns include the limited viewpoints available to station PSOs along 
Sukkwan Strait, the presence of landmasses that may obstruct 
viewpoints, and decreased effectiveness in sighting marine mammals at 
increased distances. Further, shutdown zones at greater distances than 
those in Table 9 will likely result in the DOT&PFs activities being 
shut down more frequently than is practicable for them to maintain 
their project schedule;

                                                    Table 9--Shutdown Zones During Project Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                     Shutdown zone (m)
              Activity                       Pile size             Minutes (min) or     Piles per ------------------------------------------------------
                                                                   strikes per pile        day         LF         MF         HF         PW         OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation..............  20- and 24-inch........  <=30 min...............       <=10         30         30         30         30         30
Vibratory Removal...................  16- and 24-inch........  30 min.................          2         30         30         30         30         30
Impact Installation.................  20-inch................  50 strikes.............          1         50         30         60         30         30
                                                               50 strikes.............          2         80         30         90     \1\ 40         30
                                      24-inch................  50 strikes.............          1         70         30         80         40         30
                                                               50 strikes.............          2    \1\ 100         30        120         60         30
DTH (Rock Socket)...................  20- and 24-inch........  60 min.................          1        360         30        430        200         30
                                                               120 min................          1        570         30    \2\ 500        310         30
                                                               180 min................          1        750         30    \2\ 500        400         30
                                                               240 min................          1      1,000         40    \2\ 500    \2\ 400         40
                                                               300 min................          1  \2\ 1,000         40    \2\ 500    \2\ 400         50
                                                               360 min................          1  \2\ 1,000         50    \2\ 500    \2\ 400         50
                                                               420 min................          1  \2\ 1,000         50    \2\ 500    \2\ 400         60
                                                               480 min................          1  \2\ 1,000         60    \2\ 500    \2\ 400         60
DTH (Tension Anchor)................  8-inch.................  60 min.................          1         40         30         50         30         30
                                                               120 min................          1         60         30         70         40         30
                                                               180 min................          1         80         30         90     \1\ 40         30
                                                               240 min................          1        100         30        110         30         30
                                                               300 min................          1        110         30        130         60         30
                                                               360 min................          1        120         30        150         70         30
                                                               420 min................          1        140         30        160         80         30
                                                               480 min................          1        150         30        180         80         30
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The shutdown zone is equivalent to the Level A harassment distance.
\2\ The shutdown is smaller than the Level A harassment distance.

     DOT&PF anticipates that the maximum number of piles to be 
installed and or the daily duration of pile driving or DTH use may vary 
significantly, with large differences in maximum zone sizes possible

[[Page 1078]]

depending on the work planned for a given day (Table 7). Given this 
uncertainty, DOT&PF will utilize a tiered system to identify and 
monitor the appropriate Level A harassment zones and shutdown zones on 
a daily basis, based on the maximum expected number of piles to be 
installed (impact or vibratory pile driving) or the maximum expected 
DTH duration for each day. At the start of each work day, DOT&PF will 
determine the maximum scenario 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 observed by PSO(s) for the entire work 
day, regardless of whether DOT&&PF ultimately meets the anticipated 
scenario parameters for that day;
     Marine mammals observed anywhere within visual range of 
the PSO will be tracked relative to construction activities. If a 
marine mammal is observed entering or within the shutdown zones 
indicated in Table 9, pile driving or DTH activities must be delayed or 
halted. If pile driving or DTH activities are 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 have passed 
without re-detection of the animal;
     Monitoring must take place from 30 minutes prior to 
initiation of pile driving (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;
     The DOT&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. Soft starts will not be used for vibratory pile 
installation and removal or for DTH activities. PSOs shall begin 
observing for marine mammals 30 minutes before ``soft start'' or in-
water pile installation or removal begins; and
     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.
    Based on our evaluation of the applicant's mitigation measures, as 
well as other measures considered by NMFS, NMFS has determined that the 
mitigation measures provide the means of effecting the least 
practicable impact on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, areas of 
similar significance, and on the availability of such species or stock 
for subsistence uses.

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, in 
accordance with the following:
     PSOs must be independent of the activity contractor (e.g., 
employed by a subcontractor) and have no other assigned tasks during 
monitoring periods. At least one PSO must have prior experience 
performing the duties of a PSO during construction activity pursuant to 
a NMFS-issued IHA or Letter of Concurrence. 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. PSOs must be approved by NMFS prior to beginning any activity 
subject to these IHAs;
     DOT&PF must employ at least two PSOs during all pile 
driving and DTH activities. A minimum of one PSO must be assigned to 
the active pile driving or DTH location to monitor for marine mammals 
and implement shutdown/delay procedures when applicable by calling for 
the shutdown to the hammer operator. At least one additional PSO is 
also required, and should be placed at the best practical vantage 
point(s) to ensure that the shutdown zones are fully monitored and as 
much as the Level B harassment zones are monitored as practicable; 
though the observation points may vary depending on the construction 
activity and location of the piles;
     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;
     PSOs will use a hand-held GPS device, rangefinder, or 
reticle binoculars to verify the required monitoring distance from the 
project site; and
     PSOs must record all observations of marine mammals, 
regardless of distance from the pile being driven. PSOs shall document 
any behavioral

[[Page 1079]]

reactions in concert with distance from piles being driven or removed.
    PSOs must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to record required information 
including but not limited to the number and species of marine mammals 
observed; dates and times when in-water construction activities were 
conducted; dates, times, and reason for implementation of mitigation 
(or why mitigation was not implemented when required); and marine 
mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and DTH 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 reports will 
include an overall description of work completed, a narrative regarding 
marine mammal sightings, and associated PSO data sheets. Specifically, 
the reports 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) and the 
total equipment duration for vibratory installation, removal and DTH 
for each pile or 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 (minimum, maximum, and 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 and shutdown zones, by species; and
     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.
    If no comments are received from NMFS within 30 days, the draft 
final reports will constitute the final reports. 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, NMFS 
([email protected]), and to the Alaska Regional 
Stranding Coordinator as soon as feasible. If the death or injury was 
clearly caused by the specified activity, the DOT&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 
IHAs. The DOT&PF must not resume their activities until notified by 
NMFS. The report must include the following information:
     Time, date, and location (latitude and 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 2, given that many of the anticipated 
effects of the DOT&PFs construction activities 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

[[Page 1080]]

responses to activities, impact of expected take on the population due 
to differences in population status, or impacts on habitat, they are 
described independently in the analysis below.
    Pile driving and 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 
systems. 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.
    The DOT&PF's construction activities and associated impacts will 
occur within a limited, confined area of the stocks' range. The work 
will occur in the vicinity of the seaplane dock immediately adjacent to 
Hydaburg and sound from the construction activities will be blocked by 
Sukkwan Island, Spook Island, Mushroom Island, and the coastline along 
Prince of Wales Island both southeast and northwest of the project site 
(see Figure 1-2 in the DOT&PF's application) to a maximum distance of 
5,162 m and area of 4.34 km\2\. 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. In addition, NMFS 
does not anticipate that serious injury or mortality will occur as a 
result of the DOT&PF's construction activities given the nature of the 
activity, even in the absence of required mitigation.
    Exposures to elevated sound levels produced during pile driving and 
DTH may cause behavioral disturbance of some individuals. Behavioral 
responses of marine mammals to pile driving, pile removal, and DTH 
systems at the project site are expected to be mild, short term, and 
temporary. Effects on individuals that are taken by Level B harassment, 
as enumerated in the Estimated Take section, on the basis of reports in 
the literature as well as monitoring from other similar activities, 
will likely be limited to reactions such as increased swimming speeds, 
increased surfacing time, or decreased foraging (if such activity were 
occurring) (e.g., Thorson and Reyff, 2006). 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 observable 
such as changes in vocalization patterns or increased haul out time 
(Thorson and Reyff, 2006). Additionally, some of the species present in 
the region will only be present temporarily based on seasonal patterns 
or during transit between other habitats. These temporarily present 
species will be exposed to even smaller periods of noise-generating 
activity, further decreasing the impacts. Most likely, individual 
animals will simply move away from the sound source and be temporarily 
displaced from the area, although even this reaction has been observed 
primarily only in association with impact pile driving. Because 
DOT&PF's activities could occur during any season, takes may occur 
during important feeding times. The project area though represents a 
small portion of available foraging habitat and impacts on marine 
mammal feeding for all species should be minimal.
    The activities analyzed here are similar to numerous other 
construction activities conducted along southeastern Alaska (e.g., 86 
FR 43190, August 6, 2021; 87 FR 15387, March 18, 2022), which have 
taken place with no known long-term adverse consequences from 
behavioral harassment. These reactions and behavioral changes are 
expected to subside quickly when the exposures cease and, therefore, no 
such long-term adverse consequences should be expected (e.g., Graham et 
al., 2017). The intensity of Level B harassment events will be 
minimized through use of mitigation measures described herein, which 
were not quantitatively factored into the take estimates. The DOT&PF 
will use at least two PSOs stationed strategically to increase 
detectability of marine mammals during in-water pile driving and DTH 
activities, enabling a high rate of success in implementation of 
shutdowns to avoid or minimize injury for most species. Further, given 
the absence of any major rookeries and haulouts within the estimated 
harassment zones, we assume that potential takes by Level B harassment 
will have an inconsequential short-term effect on individuals and will 
not result in population-level impacts.
    As stated in the mitigation section, DOT&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 (harbor seals, northern elephant seals, harbor porpoises, 
Dall's porpoises, humpback whales, and minke whales) to account for the 
potential that an animal could enter and remain within the Level A 
harassment zone for a duration long enough to incur PTS. Any take by 
Level A harassment is expected to arise from, at most, a small degree 
of PTS because animals will 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.
    Due to the levels and durations of likely exposure, animals that 
experience PTS will likely only receive slight PTS, i.e., minor 
degradation of hearing capabilities within regions of hearing that 
align most completely with the frequency range of the energy produced 
by DOT&PF's in-water construction activities (i.e., the low-frequency 
region below 2 kHz), not severe hearing impairment or impairment in the 
reigns of greatest hearing sensitivity. If hearing impairment does 
occur, it is most likely that the affected animal will lose a few dBs 
in its hearing sensitivity, which in most cases is not likely to 
meaningfully affect its ability to forage and communicate with 
conspecifics. There are no data to suggest that a single instance in 
which an animal accrues PTS (or TTS) and is subject to behavioral 
disturbance will result in impacts to reproduction or survival. If PTS 
were to occur, it will be at a lower level likely to accrue to a 
relatively small portion of the population by being a stationary 
activity in one particular location. 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.
    Theoretically, repeated, sequential exposure to pile driving noise 
over a long duration could result in more severe impacts to individuals 
that could affect a population. However, the limited number of non-
consecutive pile driving days for this project and the absence of any 
pinniped haulouts or other known cetacean residency patterns in the 
action area means that these types of impacts are not anticipated.
    For all species except humpback whales, there are no known BIAs 
near the project zone that will be impacted by DOT&PF's planned 
activities. For humpback whales, the whole of southeast Alaska is a 
seasonal feeding BIA from May through September (Wild et al., 2023), 
however, Sukkwan Strait 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

[[Page 1081]]

humpback during this time, it is not currently designated as critical 
habitat for humpback whales (86 FR 21082, April 21, 2021).
    The project is also not expected to have significant adverse 
effects on any marine mammal habitat. The project activities will not 
modify existing marine mammal habitat since the project will occur 
within the same footprint as existing marine infrastructure. Impacts to 
the immediate substrate are anticipated, but these will be limited to 
minor, temporary suspension of sediments, which could impact water 
quality and visibility for a short amount of time but which will not be 
expected to have any effects on individual marine mammals.
    In addition, impacts to marine mammal prey species are expected to 
be minor and temporary and 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. Overall, the area impacted by 
the project is very small compared to the available surrounding 
habitat, and does not include habitat of particular importance. The 
most likely impact to prey will be temporary behavioral avoidance of 
the immediate area. During construction activities, it is expected that 
some fish and marine mammals will temporarily leave the area of 
disturbance, thus impacting marine mammals' foraging opportunities in a 
limited portion of the foraging range. But, because of the relatively 
small area of the habitat that may be affected, and lack of any habitat 
of particular importance, the impacts to marine mammal habitat are not 
expected to cause significant or long-term negative consequences.
    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;
     Level A harassment authorized is expected to be of a lower 
degree that will not impact the fitness of any animals;
     Anticipated incidents of Level B harassment consist of, at 
worst, temporary modifications in behavior;
     The required mitigation measures (i.e., soft starts, 
shutdown zones) are expected to be effective in reducing the effects of 
the specified activity by minimizing the numbers of marine mammals 
exposed to injurious levels of sound, and by ensuring 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 low for all stocks and will not be of a duration or intensity 
expected to result in impacts on reproduction or survival;
     Minimal impacts to marine mammal habitat/prey are 
expected;
     The only known area of specific biological importance 
covers a broad area of southeast Alaska for humpback whales, and the 
project area is a very small portion of that BIA. 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 southeast Alaska 
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 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

Small Numbers

    As noted previously, only small numbers of incidental take may be 
authorized under section 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 maximum annual amount of take NMFS proposes to authorize for 
five marine mammal stocks is below one-third of the estimated stock 
abundance for all species (in fact, take of individuals is less than 
six percent of the abundance of all affected stocks, see Table 8). The 
number of animals authorized to be taken from these stocks will be 
considered small relative to the relevant stock's abundances even if 
each estimated take occurred to a new individual. Some individuals may 
return multiple times in a day, but PSOs will count them as separate 
individuals if they cannot be individually identified.
    The Alaska stock of Dall's porpoise has no official NMFS abundance 
estimate for this area, as the most recent estimate is greater than 
eight years old. Abundance estimates for Dall's porpoise in inland 
waters of southeast Alaska were calculated from 19 line-transect vessel 
surveys from 1991 to 2012 (Jefferson et al., 2019). Abundance across 
the whole period was estimated at 5,381 (CV = 0.25), 2,680 (CV = 0.20), 
and 1,637 (CV = 0.23) in the spring, summer, and fall, respectively 
(Jefferson et al., 2019). The minimum population estimate 
(NMIN) for the entire Alaska stock is assumed to correspond 
to the point estimate of a 2015 vessel-based abundance computed by Rone 
et al. (2017) in the Gulf of Alaska (N = 13,110; CV = 0.22) (Muto et 
al., 2022); however, the study area of this survey corresponds to a 
small fraction of the range of the stock and, thus it is reasonable to 
assume that the stock size is equal to or greater than that estimate 
(Muto et al., 2022). Therefore, the 22 takes of this stock authorized 
clearly represent small numbers of this stock.
    The abundance estimate for the Mexico-North Pacific stock of 
humpback whales is also considered to be unknown as estimates are based 
on data collected more than 15 years ago (Young et al., 2023). A multi-
strata mark-recapture analysis of data from 2004 through 2006 resulted 
in an abundance estimate of 5,890 (CV = 0.075) humpbacks for Southeast 
Alaska and northern British Columbia (Wade 2021); however, this 
estimate represents a mixture of whales from up to three winter areas 
(the western North Pacific (Asia), Hawaii, and Mexico), and thus does 
not represent the abundance of just the Mexico-North Pacific stock in 
its summer areas. The number of animals in the feeding areas belonging 
to the Mexico-North Pacific stock was determined by multiplying the 
abundance estimate for each feeding area (i.e., Bering Sea and Aleutian 
Islands, Gulf of Alaska, and Southeast Alaska and northern British 
Columbia) by the probability of movement between that feeding area and 
the Mexican wintering area, as estimated by Wade

[[Page 1082]]

(2021), and then adding those estimates together. This resulted in an 
estimate of 918 animals (CV = 0.217) and an NMIN estimate of 
766 animals for this stock (Young et al., 2023). While the abundance 
trend for this stock is unclear; the 32 takes authorized represent 
small numbers of this stock based on this available data.
    There is also no current or historical estimate of the Alaska minke 
whale stock, but minke whale abundance has been estimated to be over 
1,000 whales in portions of Alaska (Muto et al., 2022) so the 3 takes 
authorized represent small numbers of this stock. Additionally, the 
range of the Alaska stock of minke whales is extensive, stretching from 
the Canadian Pacific coast to the Chukchi Sea, and DOT&PF's project 
area impacts a small portion of this range. Therefore, the three takes 
of minke whale authorized is small relative to estimated survey 
abundance, even if each authorized take occurred to a new individual.
    Based on the analysis contained herein of the construction activity 
(including the mitigation and monitoring measures) and the anticipated 
take of marine mammals, NMFS finds that small numbers of marine mammals 
will 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.
    Alaska Natives have traditionally harvested subsistence resources 
in southeast Alaska for many hundreds of years, particularly large 
terrestrial mammals, marine mammals, salmon, and other fish (Alaska 
Department of Fish and Game (ADF&G), 1997). Harbor seals and sea otters 
are reported to be the marine mammal species most regularly harvested 
for subsistence in the waters surrounding Hydaburg (NOAA, 2013). An 
estimated 14.4 harbor seals were harvested by Hydaburg residents every 
year from 2000 through 2008 (ADF&G, 2009a, 2009b). Hunting usually 
occurs in the late fall and winter (ADF&G, 2009a). The ADF&G has not 
recorded harvest of cetaceans from Hydaburg (ADF&G, 2022). There are no 
subsistence activities near the project that target humpback whales, 
and subsistence hunters rarely target Steller sea lions near the 
project area.
    Approximately 93 percent of Hydaburg residents identified as Alaska 
Native (Sill and Koster, 2017) in 2012. Nearly half of all households 
harvested wild resources in 2012, with nearly all Hydaburg households 
using salmon, non-salmon fish, marine invertebrates, and vegetation 
(Sill and Koster, 2017). Only six percent of Hydaburg households 
participated in the hunting, use, or receiving of harbor seals in 2012, 
whereas up to eight percent used sea otters (Sill and Koster, 2017). 
Based on data from 2012, marine mammals account for approximately one 
percent (1,666 pounds or 756 kg) of all subsistence harvest in Hydaburg 
(Sill and Koster, 2017).
    All pile driving and DTH activities will take place in the vicinity 
of seaplane dock immediately adjacent to Hydaburg where subsistence 
activities do not generally occur. The project will not have an adverse 
impact on the availability of marine mammals for subsistence use at 
locations farther away. Some minor, short-term disturbance of the 
harbor seals or sea otters could occur, but this is not likely to have 
any measurable effect on subsistence harvest activities in the region. 
No changes to availability of subsistence resources will result from 
the specified activities. Additionally, DOT&PF is working with Haida 
Elders on the project to raise awareness and collaborate on the project 
within the local community.
    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, NMFS has determined that there will not be an unmitigable 
adverse impact on subsistence uses from the DOT&PF's construction 
activities.

Endangered Species Act

    Section 7(a)(2) of the 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 propose to authorize take for endangered or threatened species, in 
this case with NMFS' Alaska Regional Office (AKRO).
    There is one marine mammal species (Mexico DPS humpback whales) 
with confirmed occurrence in the project area that is listed as 
threatened under the ESA. AKRO issued a Biological Opinion on December 
19, 2023 under section 7 of the ESA, on the issuance of an IHA to the 
DOT&PF under section 101(a)(5)(D) of the MMPA by the NMFS Office of 
Protected Resources. The Biological Opinion concluded that the proposed 
action is not likely to jeopardize the continued existence of Mexico 
DPS humpback whales.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our action (i.e., the issuance of an IHA) with respect 
to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NAO 216-6A, which do not 
individually or cumulatively have the potential for significant impacts 
on the quality of the human environment and for which we have not 
identified any extraordinary circumstances that will 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 the DOT&PF for the potential harassment 
of small numbers of nine marine mammal species incidental to the 
Hydaburg Seaplane Base Refurbishment Project in Hydaburg, Alaska, that 
includes the previously explained mitigation, monitoring and reporting 
requirements.

    Dated: January 3, 2024.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2024-00189 Filed 1-8-24; 8:45 am]
BILLING CODE 3510-22-P