[Federal Register Volume 88, Number 138 (Thursday, July 20, 2023)]
[Notices]
[Pages 46746-46773]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-15441]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC919]


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

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible renewal.

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SUMMARY: NMFS has received a request from the Alaska Department of 
Transportation and Public Facilities (ADOT&PF) for authorization to 
take marine mammals incidental to ferry berth construction in Tongass 
Narrows in Ketchikan, Alaska. Pursuant to the Marine Mammal Protection 
Act (MMPA), NMFS is requesting comments on its proposal to issue an 
incidental harassment authorization (IHA) to incidentally take marine 
mammals during the specified activities. NMFS is also requesting 
comments on a possible one-time, 1-year renewal that could be issued 
under certain circumstances and if all requirements are met, as 
described in Request for Public Comments at the

[[Page 46747]]

end of this notice. NMFS will consider public comments prior to making 
any final decision on the issuance of the requested MMPA authorization 
and agency responses will be summarized in the final notice of our 
decision.

DATES: Comments and information must be received no later than August 
21, 2023.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email to 
[email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at 
www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.
    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: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In 
case of problems accessing these documents, please call the contact 
listed below.

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

SUPPLEMENTARY INFORMATION: 

Background

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

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment. This action 
is consistent with categories of activities identified in Categorical 
Exclusion B4 (IHAs with no anticipated serious injury or mortality) of 
the Companion Manual for NOAA Administrative Order 216-6A, which do not 
individually or cumulatively have the potential for significant impacts 
on the quality of the human environment and for which we have not 
identified any extraordinary circumstances that would preclude this 
categorical exclusion. Accordingly, NMFS has preliminarily determined 
that the issuance of the proposed IHA qualifies to be categorically 
excluded from further NEPA review.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

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

[[Page 46748]]

Facility. As such, remaining work proposed is limited to four project 
sites: Revilla New Berth, Gravina New Berth, Revilla Refurbish Existing 
Ferry Berth Facility, and Gravina Refurbish Existing Ferry Berth 
Facility. ADOT&PF has complied with all the requirements (e.g., 
mitigation, monitoring, and reporting) of the previous IHAs with the 
exception of one incident in which ADOT&PF reported that a pile had 
been removed without the presence of a Protected Species Observer (PSO) 
on site. ADOT&PF reported the incident immediately and retrained the 
Construction Contractor's Foreman and ADOT&PF's on-site representative. 
ADOT&PF also notified NMFS on May 18, 2023 that 12 20'' piles that were 
not included in the renewal, but were included in the initial IHA on 
which the renewal was based, were driven after expiration of the 
initial IHA (while the renewal was effective). Monitoring results from 
the previous IHAs are discussed in the Potential Effects of Specified 
Activities on Marine Mammals and their Habitat and the Estimated Take 
of Marine Mammals section.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN20JY23.001

BILLING CODE 3510-22-C

[[Page 46749]]

Figure 1--Tongass Narrows Project Area

Description of Proposed Activity

Overview

    ADOT&PF is making improvements to two existing ferry berths and 
constructing two new ferry berths on Gravina Island and Revillagigedo 
(Revilla) Island in Tongass Narrows, near Ketchikan, in southeast 
Alaska (Figure 1). The existing ferry facilities improve access to 
developable land on Gravina Island, improve access to the Ketchikan 
International Airport, and facilitate economic development in the 
Ketchikan Gateway Borough. The new ferry berths provide redundancy to 
the existing ferry berths. The project's proposed activities that have 
the potential to take marine mammals, by Level A harassment and Level B 
harassment, include down-the-hole (DTH) drilling of rock sockets and 
tension anchors, vibratory installation and removal of temporary steel 
pipe piles and/or H-piles, vibratory and impact installation of 
permanent steel pipe piles, and vibratory removal of permanent piles 
(in cases where work is being redone). The marine construction 
associated with the proposed activities is planned to occur over 131 
non-consecutive days over 1 year.

Dates and Duration

    ADOT&PF anticipates the project would require approximately 131 
days of pile installation and removal over the course of 1 year. 
Construction is planned to occur during daylight hours only with in-
water construction occurring 7 days per week. This IHA would be 
effective for 1 year from the date of issuance.

Specific Geographic Region

    The proposed construction project is in Tongass Narrows in 
Ketchikan, Alaska, on Revilla Island, 2.6 miles (4.2 kilometers) north 
of downtown Ketchikan, and Gravina Island, adjacent to the Ketchikan 
International Airport. All project components are located within 
approximately 0.5 miles (0.8 kilometers) of one another within the City 
of Ketchikan (Figure 1). The Revilla New Berth and Gravina New Berth 
are being constructed immediately adjacent to the existing ferry berths 
on Revilla and Gravina Islands, respectively.
    A description of Tongass Narrows was provided in the proposed 
Federal Register notice for an IHA associated with previous work 
completed at these project sites (87 FR 5980, February 2, 2022). Please 
refer to that notice for additional information.

Detailed Description of the Specified Activity

    Planned construction includes the installation and continued 
construction of new ferry facilities and the renovation of existing 
structures. As stated above, the four proposed construction components 
include: Revilla New Berth, Gravina New Berth, Revilla Refurbish 
Existing Ferry Berth Facility, and Gravina Refurbish Existing Ferry 
Berth Facility. Each of the project components would include 
installation and/or removal of steel pipe piles that are 24 or 30-
inches diameter, or steel 14-inch H-piles using vibratory, impact, and/
or DTH methods (Table 1). ADOT&PF does not plan to operate multiple 
hammers concurrently.
Revilla New Berth
    The Revilla New Berth facility will consist of a 7,400-square-foot 
(687.5 square meter) pile-supported approach trestle at the shore side 
of the ferry terminal and a 1,500-square-foot (139.4 square meter) 
pile-supported approach trestle extension located landside and north of 
the new approach trestle. A 25-foot (17.6 meters) by 142-foot (43.3 
meters) steel transfer bridge with vehicle traffic lane and separated 
pedestrian walkway will extend from the trestle to a new 2,200- square-
foot (204.4 square meter) steel float and apron. The steel float will 
be supported by three guide pile dolphins. Two new stern berth dolphins 
with fixed hanging fenders and three new floating fender dolphins will 
be constructed to moor vessels. The new apron will be supported by 
three new guide pile dolphins. Water depths at the dolphins will reach 
approximately 60 feet (18.3 meters). Some permanent piles originally 
installed in previous years may need to be removed and reinstalled in 
the correct locations (Table 1).
Gravina New Berth
    The Gravina New Berth facility will consist of an approximately 
7,000-square-foot (650.3 square meter) pile-supported approach trestle 
at the shore side of the ferry terminal. A 25-foot (17.6 meters) by 
142-foot (43.3 meters) steel transfer bridge with a vehicle traffic 
lane and separated pedestrian walkway will lead to a new 2,200- square-
foot 204.4 square meter steel float and apron. The steel float will be 
supported by three new guide pile dolphins. Ferry berthing will be 
supported by two new stern berth dolphins and three new floating fender 
dolphins. To support the new facility, a new bulkhead retaining wall 
will be constructed between the existing ferry berth and the new 
approach trestle. A new fill slope measuring approximately 21,200 
square feet (1,969.5 square meter) will be constructed west of the 
approach trestle. Upland improvements include widening of the ferry 
approach road, retrofits to the existing pedestrian walkway, 
installation of utilities, and construction of a new employee access 
walkway.
Revilla Refurbish Existing Ferry Berth
    Improvements to the existing Revilla Island Ferry Berth will 
include the following: (1) replace the transfer bridge, (2) replace 
rubber fender elements and fender panels, (3) replace one 24-inch pile 
on the floating fender dolphin, and (4) replace the bridge float with a 
concrete or steel float of the same dimensions. Construction of the 
transfer bridge, bridge float, and fender elements will occur above 
water. The only in-water work will be pile installation and removal 
associated with construction of the one remaining dolphin.
Gravina Refurbish Existing Ferry Berth
    Improvements to the existing Gravina Island Ferry Berth will 
include the following: (1) replace the transfer bridge, (2) remove the 
catwalk and dolphins, (3) replace the bridge float with a concrete or 
steel float of the same dimensions, (4) construct a floating fender 
dolphin, and (5) construct four new breasting dolphins. Construction of 
the transfer bridge, catwalk, and bridge float will occur above water. 
The only in-water work will be pile installation and removal associated 
with construction of the dolphins. Some piles installed in previous 
years may need to be removed and reinstalled (Table 1).
    Across the four project sites, three methods of pile installation 
are anticipated. These include use of vibratory and impact hammers and 
use of DTH systems to make holes for rock sockets and tension anchors 
at some locations. Installation of steel piles through the overburden 
layer would be accomplished using vibratory or impact methods. Where 
the overburden is deep, rock socketing or anchoring (described below) 
is not required, and the final approximately 10 ft (3 m) of driving 
would be conducted using an impact hammer. Some permanent piles would 
be battered (i.e., installed at an angle). In shallow overburden, an 
impact hammer would be used to seat the piles into competent bedrock 
before a DTH system would be used to create holes for the rock sockets 
and/or tension anchors. The pile installation methods used would depend 
on overburden depth and conditions at each pile location. A description 
of DTH methods for rock

[[Page 46750]]

socketing and tension anchor installation was provided in the notice of 
proposed IHA associated with previous work completed at these project 
sites (87 FR 5980, February 2, 2022). Vibratory methods would also be 
used to remove temporary steel pipe piles. These proposed activities 
and the noise they produce have the potential to take marine mammals, 
by Level A harassment and Level B harassment of marine mammals.
    The estimated installation rate of piles vary depending on pile 
type and location (Table 1). On some days, more or fewer piles or 
partial piles may be installed. It would likely not be possible to 
install an individual permanent pile to refusal with a vibratory 
hammer, use DTH methods for the rock socket, impact proof, and install 
the tension anchor on the same day. The construction crew may use a 
single installation method for multiple piles on a single day or find 
other efficiencies to increase production; the anticipated ranges of 
possible values are provided in Table 1.
    Approximately 131 days of pile installation and removal are 
anticipated (Table 1). Note that ADOT&PF's application reflects 152 
construction days rather than 131, but this number has been adjusted to 
account for one of five sites that has been completed. Up to 26 
permanent piles previously installed will be removed and reinstalled. 
An additional 51 permanent piles will be installed. An additional 84 
template piles will be installed and removed.
    Above-water work would consist of the installation of concrete or 
steel platform decking panels, transfer bridges, dock-mounted fenders, 
pedestrian walkways, gangways, and utility lines. Upland construction 
activities will consist of new terminal facilities, staging areas, 
parking lot expansions, new roadways, retaining walls, stairways, and 
pedestrian walkways. No in-water noise is anticipated in association 
with above-water and upland construction activities, and no associated 
take of marine mammals is anticipated from the noise or visual 
disturbance. Therefore, above-water and upland construction activities 
are not discussed further in this document.

                                                    Table 1--Pile Details for Each Project Component
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       Project component                                                   Average
--------------------------------                                Average      DTH       Average DTH     Impact
                                            Number    Number   vibratory   duration   duration for     strikes      Estimated     Average      Days of
                                  Number    of rock     of      duration   for rock      tension      per pile    total number   piles per  installation
           Pile type             of piles   sockets   tension   per pile   sockets     anchors per    (duration   of hours per      day      and removal
                                                      anchors  (minutes)   per pile  pile (minutes)      in       pile (range)    (range)
                                                                          (minutes)                   minutes)
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Revilla New Berth
 (Installation):
    30'' Permanent.............        13  ........         3         30  .........         120-240    200 (15)   2 (0.75-4.75)    1 (1-3)            13
    24'' or 14'' H Template....        28  ........  ........        120  .........  ..............     50 (15)            2.25    2 (1-4)            14
Revilla New Berth (Removal):
    30'' Permanent.............        13  ........  ........         60  .........  ..............  ..........               1    3 (1-6)             5
    24'' or 14'' H Template....        28  ........  ........         60  .........  ..............  ..........               1    6 (1-8)             5
Gravina New Berth
 (Installation):
    24'' Permanent.............        27        11        28         30    180-360         120-240    200 (15)  6 (2.75-10.75)    1 (1-3)            27
    24'' or 14'' H Template....        24  ........  ........        120  .........  ..............     50 (15)            2.25    2 (1-4)            12
Gravina New Berth (Removal):
    24'' or 14'' H Template....        24  ........  ........         60  .........  ..............  ..........               1    6 (1-8)             4
Revilla Refurbish Existing
 Ferry Berth Facility
 (Installation):
    24'' Permanent.............         1  ........  ........        120  .........  ..............    200 (15)            2.25          1             1
Revilla Refurbish Existing
 Ferry Berth Facility
 (Removal):
    24'' Permanent.............         1  ........  ........         60  .........  ..............  ..........               1          1             1
Gravina Refurbish Existing
 Ferry Berth Facility
 (Installation):
    24'' Permanent.............        23        13        16         30    180-360   120 (120-240)    200 (15)  6 (2.75-10.75)    1 (1-3)            23
    24'' or 14'' H Template....        32  ........  ........        120  .........  ..............     50 (15)            2.25    2 (1-4)            16
Gravina Refurbish Existing
 Ferry Berth Facility
 (Removal):
    24'' Permanent.............        12  ........  ........         60  .........  ..............  ..........               1    3 (1-6)             4
    24'' or 14'' H Template....        32  ........  ........         60  .........  ..............  ..........               1    6 (1-8)             6
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    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, incorporated here by reference, instead of 
reprinting the information. Additional information regarding population 
trends and threats may be found in NMFS' Stock Assessment Reports 
(SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these 
species (e.g., physical and behavioral descriptions) may be found on 
NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
proposed to be authorized for this activity, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a

[[Page 46751]]

marine mammal stock while allowing that stock to reach or maintain its 
optimum sustainable population (as described in NMFS' SARs). While no 
serious injury or mortality is anticipated or proposed to be authorized 
here, PBR and annual serious injury and mortality from anthropogenic 
sources are included here as gross indicators of the status of the 
species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Alaska and Pacific Ocean 2021 SARs (e.g., Muto et al., 2022, 
Caretta et al. 2022) and the draft 2022 SARs (e.g., Young et. al., 
2022). All values presented in Table 2 are the most recent available at 
the time of publication (including from the draft 2022 SARs) and are 
available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                       Table 2--Marine Mammal Species 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--Infraorder Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Minke Whale \4\.................  Balaenoptera             AK.....................  -,-,N               N/A (N/A, N/A, N/A)...        UND          0
                                       acutorostrata.
    Fin Whale \5\...................  Balaenoptera physalus..  Northeast Pacific......  E, D, Y             3,168 (0.26, 2,554,           UND        0.6
                                                                                                             2013).
    Humpback Whale..................  Megaptera novaeangliae.  Central North Pacific..  -,-,Y               10,103 (0.3, 7,891,           3.4       4.46
                                                                                                             2006).
Family Eschrichtiidae:
    Gray whale......................  Eschrichtius robustus..  Eastern North Pacific..  -,-,N               26,960 (0.05, 25,849,         801        131
                                                                                                             2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Pacific White-sided Dolphin.....  Lagenorhynchus           N Pacific..............  -,-,N               26,880 (N/A, N/A,             UND          0
                                       obliquidens.                                                          1990).
    Killer Whale....................  Orcinus orca...........  Eastern North Pacific    -,-,N               1,920, (N/A, 1,920,            19        1.3
                                                                Alaska Resident.                             2019).
                                                               Eastern North Pacific    -,-,N               302 (N/A, 302, 2018)..        2.2        0.2
                                                                Northern Resident.
                                                               West Coast Transient...  -,-,N               349 (N/A, 349, 2018)..        3.5        0.4
Family Phocoenidae (porpoises):
    Harbor Porpoise \6\.............  Phocoena phocoena......  Southeast Alaska.......  -,-,Y               1302 (0.21, 1057,             UND         34
                                                                                                             2019).
    Dall's Porpoise \7\.............  Phocoenoides dalli.....  Alaska.................  -,-,N               15,432 (0.097, 13,110,        131         37
                                                                                                             2021).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               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):
    Northern Elephant Seal..........  Mirounga angustirostris  CA Breeding............  -,-,N               187,386 (N/A, 85,369,       5,122       13.7
                                                                                                             2013).
    Harbor Seal.....................  Phoca vitulina.........  Clarence Strait........  -,-,N               27,659 (N/A, 24,854,          746         40
                                                                                                             2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV
  is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\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 M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ No population estimates have been made for the number of minke whales in the entire North Pacific. Some information is available on the numbers of
  minke whales on some areas of Alaska, but in the 2009, 2013 and 2015 offshore surveys, so few minke whales were seen during the surveys that a
  population estimate for the species in this area could not be determined (Rone et al., 2017). Therefore, this information is N/A (not available).
\5\ The best available abundance estimate for this stock is not considered representative of the entire stock as surveys were limited to a small portion
  of the stock's range. Based upon this estimate and the Nmin, the PBR value is likely negatively biased for the entire stock.
\6\ Abundance estimates assumed that detection probability on the trackline was perfect; work is underway on a corrected estimate. Additionally,
  preliminary data results based on eDNA analysis show genetic differentiation between harbor porpoise in the northern and southern regions on the
  inland waters of southeast Alaska. Geographic delineation is not yet known. Data to evaluate population structure for harbor porpoise in Southeast
  Alaska have been collected and are currently being analyzed. Should the analysis identify different population structure than is currently reflected
  in the Alaska SARs, NMFS will consider how to best revise stock designations in the future.
\7\ Previous abundance estimates covering the entire stock's range are no longer considered reliable and the current estimates presented in the SARs and
  reported here only cover a portion of the stock's range. Therefore, the calculated Nmin and PBR is based on the 2015 survey of only a small portion of
  the stock's range. PBR is considered to be biased low since it is based on the whole stock whereas the estimate of mortality and serious injury is for
  the entire stock's range.

    On January 24, 2023, NMFS published the draft 2022 SARs (https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region). The Alaska and Pacific Ocean

[[Page 46752]]

SARs include a proposed update to the humpback whale and harbor 
porpoise stock structures. The new humpback whale structure, if 
finalized, would modify the MMPA-designated stocks to align more 
closely with the ESA-designated Distinct Population Segments (DPS). The 
new harbor porpoise structure, if finalized, would modify the Southeast 
Alaska stock into three stocks: the Northern Southeast Alaska Inland 
Waters, Southern Southeast Alaska Inland Waters, and Yakutat/Southeast 
Alaska Offshore Waters. Please refer to the draft 2022 Alaska and 
Pacific Ocean SARs for additional information.
    NMFS Office of Protected Resources, Permits and Conservation 
Division has generally considered peer-reviewed data in draft SARs 
(relative to data provided in the most recent final SARs), when 
available, as the best available science, and has done so here for all 
species and stocks, with the exception of the new proposals to revise 
harbor porpoise and humpback whale stock structure. Given that the 
proposed changes to these stock structures involve application of 
NMFS's Guidance for Assessing Marine Mammals Stocks and could be 
revised following consideration of public comments, it is more 
appropriate to conduct our analysis in this proposed authorization 
based on the status quo stock structures identified in the most recent 
final SARs for these species (2021; Muto et al., 2022).
    As indicated above, all 11 species (with 13 managed stocks) in 
Table 2 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur.
    In addition, the northern sea otter may be found in Tongass 
Narrows. However, northern sea otters are managed by the U.S. Fish and 
Wildlife Service and are not considered further in this document.

Minke Whale

    Minke whale surveys in Southeast Alaska have consistently 
identified individuals throughout inland waters in low numbers 
(Dahlheim et al. 2009). All sightings were of single minke whales, 
except for a single sighting of multiple minke whales. Surveys took 
place in spring, summer, and fall, and minke whales were present in low 
numbers in all seasons and years. No information appears to be 
available on the winter occurrence of minke whales in Southeast Alaska.
    There are no known occurrences of minke whales within the project 
area. No minke whales were reported during the nearby City of Ketchikan 
(COK) Rock Pinnacle Blasting Project (Sitkiewicz 2020) located 
approximately 2.5 miles (4 kilometers) southeast of the proposed 
project site, or across 8 months of monitoring at Ward Cove Cruise Ship 
Dock in 2020, located approximately 3.7 miles (6 kilometers) northwest 
of the Project site (Power Systems and Supplies of Alaska, 2020). 
Additionally, no minke whales were observed during the marine mammal 
monitoring that took place during construction of previous components 
of the Tongass Narrows Project (ADOT&PF 2021, 2022, 2023). However, 
since minke whale have been observed in southeast Alaska, including in 
Clarence Strait (Dahlheim et al., 2009), it is possible the species 
could occur near the project area. Future observations of minke whale 
in the project area are expected to be rare.

Fin Whale

    Fin whales in the Northeast Pacific are typically distributed off 
the coast of the Gulf of Alaska and the Bering and Chukchi Seas. They 
are seldom detected outside the Gulf of Alaska in summer months, 
suggesting that the northern populations are migratory (Muto et al. 
2021). They typically inhabit deep, offshore waters and often travel in 
open seas away from coasts. They often occur in social groups of two to 
seven individuals. Fin whales are not expected to occur in Tongass 
Narrows, but a single fin whale was recently observed in Clarence 
Strait (Scheurer, personal communication).

Humpback Whale

    Humpback whales in the project area are predominantly of the Hawaii 
DPS, which is not ESA-listed. However, based on a comprehensive photo-
identification study, individuals of the Mexico DPS, which is listed as 
threatened, are known to occur in Southeast Alaska. Individuals of 
different DPSs are known to intermix on feeding grounds; therefore, all 
waters off the coast of Alaska should be considered to have ESA-listed 
humpback whales. Approximately 2 percent of all humpback whales in 
Southeast Alaska and northern British Columbia are of the Mexico DPS, 
while all others are of the Hawaii DPS (NMFS 2021).
    The stock delineations of humpback whales under the MMPA are 
currently under review. Until this review is complete, NMFS considers 
humpback whales in Southeast Alaska to be part of the Central North 
Pacific stock, with a status of endangered under the ESA and 
designations of strategic and depleted under the MMPA (Muto et al. 
2021).
    The project area overlaps a Biologically Important Area (BIA) 
identified as important for humpback whale feeding (Wild et al., 2023). 
The BIA that overlaps the project area is active May through September, 
which overlaps with ADOT&PF's planned work period (any time of year). 
According to the criteria outlined in Harrison et al. (2023), the BIA 
is considered to be of lower importance, has low boundary certainty, 
and limited data to support the identification of the BIA. The BIA was 
identified as having ephemeral spatiotemporal variability.
    Most humpback whales migrate to other regions during the winter to 
breed, but rare events of over-wintering humpbacks have been noted, and 
may be attributable to staggered migration (Straley, 1990; Straley et 
al. 2018). Group sizes in Southeast Alaska generally range from one to 
four individuals (Dahlheim et al. 2009). No systematic studies have 
documented humpback whale abundance near Ketchikan. Anecdotal 
information suggests that this species is present in low numbers year-
round in Tongass Narrows, with the highest abundance during summer and 
fall. PSOs associated with previous construction activities at this 
site have monitored the project site across 215 days between October 
2020--February 2021, May 2021--February 2022, and March 2022--December 
2022 (ADOT&PF 2021, 2022, 2023). During this time, 80 humpback whales 
were observed, or an average of 0.37 humpback whales per day. According 
to ADOT&PF, the average group size was 1.25 humpback whales and the 
maximum group size was 4 humpback whales. Humpbacks were also detected 
during marine mammal monitoring associated with other projects in 
Tongass Narrows. The COK Rock Pinnacle project reported one humpback 
whale sighting of one individual during the project (December 2019--
January 2020) (Sitkiewicz 2020). During the Ward Cove Cruise Ship Dock 
Construction, PSOs observed 28 sightings of humpbacks on 18 days of in 
water work that occurred between February and September 2020, with at 
least one humpback being recorded every month. A total of 42 
individuals were recorded and group sizes ranged from solo whales to 
pods of up to 6 (Power Systems & Supplies of Alaska 2020). Humpbacks 
were recorded in each month of construction, with the most individuals 
(10) being recorded in May, 2020.

Gray Whale

    Gray whales are distributed throughout the North Pacific Ocean and

[[Page 46753]]

are found primarily in shallow coastal waters (Muto et al., 2021). Gray 
whales in the Eastern North Pacific stock range from the southern Gulf 
of California, Mexico to the arctic waters of the Bering and Chukchi 
Seas. Gray whales are generally solitary and travel together alone or 
in small groups.
    Gray whales are rare in the action area and unlikely to occur in 
Tongass Narrows. They were not observed during the Dahlheim et al. 
(2009) surveys of Alaska's inland waters with surveys conducted in the 
spring, summer and fall months. No gray whales were reported during the 
COK Rock Pinnacle Blasting Project (Sitkiewicz, 2020) or during 
monitoring surveys conducted between February and September 2020 as 
part of the Ward Cove Cruise Ship Dock (Power Systems & Supplies of 
Alaska, 2020), nor were they observed during 215 days of monitoring 
associated with the previous ADOT&PF Tongass Narrows construction 
activities (ADOT&PF 2021, 2023). However a gray whale could migrate 
through or near the project during November especially.
    There is an ongoing Unusual Mortality Event (UME) involving gray 
whales on the Pacific Coast (https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and). A definitive cause has not been found for the 
UME but many of the animals show signs of emaciation. These findings 
are not consistent across all of the whales examined, so more research 
is needed. As part of the UME investigation process, NOAA has assembled 
an independent team of scientists to coordinate with the Working Group 
on Marine Mammal Unusual Mortality Events to review the data collected, 
sample stranded whales, consider possible causal-linkages between the 
mortality event and recent ocean and ecosystem perturbations, and 
determine the next steps for the investigation.

Pacific White-Sided Dolphin

    Pacific white-sided dolphins are a pelagic species inhabiting 
temperate waters of the North Pacific Ocean and along the coasts of 
California, Oregon, Washington, and Alaska (Muto et al., 2021). Despite 
their distribution mostly in deep, offshore waters, they also occur 
over the continental shelf and near shore waters, including inland 
waters of Southeast Alaska (Ferrero and Walker 1996). The North Pacific 
stock occurs within the project area. Group sizes have been reported to 
range from 40 to over 1,000 animals, but groups of between 10 and 100 
individuals (Stacey and Baird 1991) occur most commonly. Seasonal 
movements of Pacific white-sided dolphins are not well understood, but 
there is evidence of both north-south seasonal movement (Leatherwood et 
al. 1984) and inshore-offshore seasonal movement (Stacey and Baird 
1991).
    Pacific white-sided dolphins are rare in the inside passageways of 
Southeast Alaska. Most observations occur off the outer coast or in 
inland waterways near entrances to the open ocean. According to Muto et 
al. (2018), aerial surveys in 1997 sighted one group of 164 Pacific 
white-sided dolphins in Dixon entrance to the south of Tongass Narrows. 
Surveys in April and May from 1991 to 1993 identified Pacific white-
sided dolphins in Revillagigedo Channel, Behm Canal, and Clarence 
Strait (Dahlheim and Towell 1994). These areas are contiguous with the 
open ocean waters of Dixon Entrance. Dalheim et al. (2009) frequently 
encountered Pacific white-sided dolphin in Clarence Strait with 
significant differences in mean group size and rare enough encounters 
to limit the seasonality investigation to a qualitative note that 
spring featured the highest number of animals observed. These 
observations were noted most typically in open strait environments, 
near the open ocean. Mean group size was over 20, with no recorded 
winter observations nor observations made in the Nichols Passage or 
Behm Canal, located on either side of the Tongass Narrows.
    Pacific white-sided dolphins were not observed during the 215 days 
of marine mammal monitoring associated with ADOT&PF's previous 
construction activities at this site (ADOT&PF 2021, 2023). There were 
also no sightings of Pacific white-sided dolphins during the COK Rock 
Pinnacle Blasting Project during monitoring surveys conducted in 
December 2019 and January 2020 (Sitkiewicz 2020) nor during monitoring 
surveys for the Ward Cove Cruise Ship Dock Project (Power Systems and 
Supplies of Alaska, 2020).
    Observational data and anecdotal information discussed above, 
indicates there is a rare, however, slight potential for Pacific white-
sided dolphins to occur in the project area.

Killer Whale

    Of the eight killer whale stocks that are recognized within the 
Pacific U.S. Exclusive Economic Zone, this proposed IHA considers only 
the Eastern North Pacific Alaska Resident stock (Alaska Resident 
stock), Eastern North Pacific Northern Resident stock (Northern 
Resident stock), and West Coast Transient stock, because all other 
stocks occur outside the geographic area under consideration (Muto et 
al., 2021).
    There are three distinct ecotypes, or forms, of killer whales 
recognized: Resident, Transient, and Offshore. The three ecotypes 
differ morphologically, ecologically, behaviorally, and genetically. 
Surveys between 1991 and 2007 encountered resident killer whales during 
all seasons throughout Southeast Alaska. Both residents and transients 
were common in a variety of habitats and all major waterways, including 
protected bays and inlets. There does not appear to be strong seasonal 
variation in abundance or distribution of killer whales, but there was 
substantial variability between years during this study (Dahlheim et 
al., 2009). Spatial distribution has been shown to vary among the 
different ecotypes, with resident and, to a lesser extent, transient 
killer whales more commonly observed along the continental shelf, and 
offshore killer whales more commonly observed in pelagic waters (Rice 
et al., 2021).
    Transient killer whales are often found in long-term stable social 
units (pods) of 1 to 16 whales. Average pod sizes in Southeast Alaska 
were 6.0 in spring, 5.0 in summer, and 3.9 in fall. Pod sizes of 
transient whales are generally smaller than those of resident social 
groups. Resident killer whales occur in larger pods, ranging from 7 to 
70 whales that are seen in association with one another more than 50 
percent of the time (Dahlheim et al., 2009; NMFS 2016b). In Southeast 
Alaska, resident killer whale mean pod size was approximately 21.5 in 
spring, 32.3 in summer, and 19.3 in fall (Dahlheim et al., 2009).
    While no systematic studies of killer whales have been conducted in 
or around Tongass Narrows, killer whales have been observed in Tongass 
Narrows year-round and are most common during the summer Chinook salmon 
run (May-July). During this time, Ketchikan residents have reported 
pods of 20-30 whales and during the 2016/2017 winter a pod of 5 whales 
was observed in Tongass Narrows (84 FR 36891, July 30, 2019).
    Across the 215 days of monitoring during ADOT&PF's previous Tongass 
Narrows construct activities, a total of 78 killer whales were 
observed, for an average observation rate of 0.36 per day (ADOT&PF 
2021, 2023). According to ADOT&PF, the average group size observed was 
4.6 individuals while the maximum group size was eight. Killer whales 
have been observed occasionally during other projects completed in the 
Tongass Narrows. During the COK's

[[Page 46754]]

monitoring for the Rock Pinnacle Removal project in December 2019 and 
January 2020, no killer whales were observed (Sitkiewicz 2020). Over 8 
months of monitoring at the Ward Cove Cruise Ship Dock in 2020, killer 
whales were only observed on 2 days in March (Power Systems and 
Supplies of Alaska, 2020). These observations included a sighting of 
one pod of two killer whales and a second pod of five individuals 
travelling through the project area. Killer whales tend to transit 
through Tongass Narrows and do not linger in the project area.

Harbor Porpoise

    In the eastern North Pacific Ocean, the harbor porpoise ranges from 
Point Barrow, along the Alaska coast, and down the west coast of North 
America to Point Conception, California. The stock delineations of 
harbor porpoise under the MMPA are currently under review. Until this 
review is complete, NMFS considers harbor porpoise in Southeast Alaska 
to be divided into three stocks, based primarily on geography: The 
Bering Sea stock, the Southeast Alaska stock, and the Gulf of Alaska 
stock. The Southeast Alaska stock ranges from Cape Suckling to the 
Canadian border (Muto et al. 2021). Only the Southeast Alaska stock is 
considered herein because the other stocks occur outside the geographic 
area under consideration. Harbor porpoises frequent primarily coastal 
waters in Southeast Alaska (Dahlheim et al. 2009) and occur most 
frequently in waters less than 100 meters (328 feet) deep (Hobbs and 
Waite 2010; Dahlheim et al. 2015).
    Studies of harbor porpoises reported no evidence of seasonal 
changes in distribution for the inland waters of Southeast Alaska 
(Dahlheim et al. 2009).
    Harbor porpoises often travel alone or in small groups less than 10 
individuals (Schmale 2008). According to aerial surveys of harbor 
porpoise abundance in Alaska conducted in 1991-1993, mean group size in 
Southeast Alaska was calculated to be 1.2 animals (Dahlheim et al. 
2000).
    Harbor porpoises prefer shallower waters (Dahlheim et al. 2015) and 
generally avoid areas with elevated levels of vessel activity and noise 
such as Tongass Narrows. However, harbor porpoises were sighted on 3 
days of in-water work during monitoring associated with the Ward Cove 
Cruise Ship Dock, with three sightings of 15 individuals sighted in 
March and April, 2020 (Power Systems and Supplies of Alaska, 2020). 
Solo individuals and pods of up to 10 were identified as swimming and 
travelling 2,500 m to 2,800 m from in-water work. During ADOT&PF's 
marine mammal monitoring of Tongass Narrows, 21 harbor porpoises were 
observed during the March-December 2022 season, and ADOT&PF recently 
reported that 4 harbor porpoise were observed in the project area. 
Across all years, ADOT&PF reported an average group size of 3.5 and 
maximum group size was 5. Marine mammal monitoring associated with the 
COK Rock Pinnacle Removal project did not observe any harbor porpoise 
during surveys conducted in December 2019 and January 2020 (Sitkiewicz 
2020). As such, Harbor porpoises are expected to be present in the 
project area only a few times per year.

Dall's Porpoise

    Dall's porpoises are found throughout the North Pacific, from 
southern Japan to southern California north to the Bering Sea. All 
Dall's porpoises in Alaska are of the Alaska stock. This species can be 
found in offshore, inshore, and nearshore habitat.
    Jefferson et al. (2019) presents historical survey data showing few 
sightings in the Ketchikan area, and based on these occurrence 
patterns, concludes that Dall's porpoise rarely come into narrow 
waterways, like Tongass Narrows. The mean group size in Southeast 
Alaska is estimated at approximately three individuals (Dahlheim et al. 
2009; Jefferson 2019). Anecdotal reports suggest that Dall's porpoises 
are found northwest of Ketchikan near the Guard Islands, where waters 
are deeper, as well as in deeper waters to the southeast of Tongass 
Narrows. This species may occur in the project area a few times per 
year.
    Marine mammal monitoring associated with the COK Rock Pinnacle 
Removal project did not observe any Dall's porpoise during surveys 
conducted in December 2019 and January 2020 (Sitkiewicz 2020). However, 
eight Dall's porpoises were observed on 2 days of in-water work during 
monitoring associated with the Ward Cove Cruise Ship Dock in March and 
April 2020 (Power Systems and Supplies of Alaska, 2020). Additionally, 
28 Dall's porpoise were observed during ADOT&PF's Tongass Narrows 
marine mammal monitoring across 215 days (ADOT&PF 2021, 2023). ADOT&PF 
reported that the average group size across all years was 5.6 and the 
maximum group size was 10.

Steller Sea Lion

    Steller sea lions were listed as threatened range-wide under the 
ESA on November 26, 1990 (55 FR 49204). Steller sea lions were 
subsequently partitioned into the western and eastern DPSs (and MMPA 
stocks) in 1997 (62 FR 24345, May 5, 1997). The eastern DPS remained 
classified as threatened until it was delisted in November 2013. The 
western DPS (those individuals west of 144[deg] W longitude or Cape 
Suckling, Alaska) was upgraded to endangered status following 
separation of the DPSs, and it remains endangered today. There is 
regular movement of both DPSs across this 144[deg] W longitude boundary 
(Jemison et al. 2013), however, due to the distance from this DPS 
boundary, it is likely that only eastern DPS Steller sea lions are 
present in the project area. Therefore, animals potentially affected by 
the project are assumed to be part of the eastern DPS.
    There are several mapped and regularly monitored long-term Steller 
sea lion haulouts surrounding Ketchikan, such as West Rocks (36 miles 
(58 kilometers) from Ketchikan) or Nose Point (37 miles (60 kilometers) 
from Ketchikan), but none are known to occur within Tongass Narrows 
(Fritz et al. 2016). The nearest known Steller sea lion haulout is 
located approximately 20 miles (58 kilometers) west/northwest of 
Ketchikan on Grindall Island (Figure 4-1 in application). Summer counts 
of adult and juvenile sea lions at this haulout since 2000 have 
averaged approximately 191 individuals, with a range from 6 in 2009 to 
378 in 2008. Only two winter surveys of this haulout have occurred. In 
March 1993, a total of 239 individuals were recorded, and in December 
1994, a total of 211 individuals were recorded. No sea lion pups have 
been observed at this haulout during surveys. Although this is a 
limited and dated sample, it suggests that abundance may be consistent 
year-round at the Grindall Island haulout.
    Steller sea lions occur in Tongass Narrows year-round, and 
anecdotal reports suggest an increase in abundance from March to early 
May during the herring spawning season, and another increase in late 
summer associated with salmon runs. Overall sea lion presence in 
Tongass Narrows tends to be lower in summer than in winter (Federal 
Highway Administration 2017). During summer, Steller sea lions may 
aggregate outside the project area, at rookery and haulout sites. 
During the 215 days of marine mammal monitoring that took place during 
construction of previous components of the Tongass Narrows Project, a 
total of 322 Steller sea lions were observed (ADOT&PF 2021, 2023). 
Average group size reported was 1.25 individuals and maximum group size 
observed was five individuals. At least one individual was observed 
during

[[Page 46755]]

each month that monitoring took place. Monitoring during construction 
of the Ward Cove Dock, recorded 181 individual sea lions on 44 days 
between February and September 2020 (Power Systems & Supplies of 
Alaska, 2020). Most sightings occurred in February (45 sightings of 88 
sea lions) and March (34 sightings of 45 sea lions); the fewest number 
of sightings were observed in May (one sighting of one sea lion) (Power 
Systems & Supplies of Alaska, 2020).

Northern Elephant Seal

    Northern elephant seals breed and give birth in California and Baja 
California, primarily on offshore islands (Stewart et al., 1994). 
Spatial segregation in foraging areas between males and females is 
evident from satellite tag data (Le Beouf et al., 2000). Males migrate 
to the Gulf of Alaska and western Aleutian Islands along the 
continental shelf to feed on benthic prey, while females migrate to 
pelagic areas in the Gulf of Alaska and the central North Pacific to 
feed on pelagic prey (Le Beouf et al., 2000). Elephant seals spend a 
majority of their time at sea (average of 74.7 days during post 
breeding migration and an average of 218.5 days during the postmolting 
migration; Robinson et al., 2012). Although northern elephant seals are 
known to visit the Gulf of Alaska to feed on benthic prey, they rarely 
occur on the beaches of Alaska.
    Despite the low probability of northern elephant seals entering the 
project area, there have been recent reports of elephant seals 
occurring in and near the Tongass Narrows. Two northern elephant seals 
were observed during ADOT&PF's Tongass Narrows construction in 2022 
(ADOT&PF 2021, 2023).

Harbor Seal

    Harbor seals inhabit coastal and estuarine waters off Alaska. They 
haul out on rocks, reefs, beaches, and drifting glacial ice. They are 
generally non-migratory, with local movements associated with such 
factors as tides, weather, season, food availability, and reproduction 
(Muto et al., 2021). They are opportunistic feeders and often adjust 
their distribution to take advantage of locally and seasonally abundant 
prey (Womble et al., 2009; Allen and Angliss, 2015).
    Harbor seals in Tongass Narrows are recognized as part of the 
Clarence Strait stock. Distribution of the Clarence Strait stock ranges 
from the east coast of Prince of Wales Island from Cape Chacon north 
through Clarence Strait to Point Baker and along the east coast of 
Mitkof and Kupreanof Islands north to Bay Point, including Ernest 
Sound, Behm Canal, and Pearse Canal (Muto et al., 2021). In the project 
area, they tend to be more abundant during spring, summer and fall 
months when salmon are present in Ward Creek. During marine mammal 
monitoring associated with ADOT&PF's previous Tongass Narrows 
construction activities, 550 harbor seals were observed with an average 
of 1.2 harbor seals per day and a maximum group size of 5. During pre-
and post-blasting monitoring completed for the COK pinnacle rock 
blasting project a total of 21 harbor seal sightings of 24 individuals 
were observed over 76.2 hours (Sitkiewicz 2020). Additionally, 
information from PSOs associated with on-going construction indicate a 
small number of harbor seals are regularly sighted at about 820 feet 
(250 meters) from the Project location (Wyatt, personal communication).
    There are two key harbor seal haulouts about 7.1 miles (11.5 
kilometers) from the project area on a mid-channel island to the 
southeast of the project site. Each haulout was monitored in 2022 with 
10 harbor seals present at one site and 50 harbor seals present at the 
other (Richland, personal communication).

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 3.

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

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

[[Page 46756]]

please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact marine mammals and their habitat. 
The Estimated Take of Marine Mammals section later in this document 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
section, to draw conclusions regarding the likely impacts of these 
activities on the reproductive success or survivorship of individuals 
and whether those impacts are reasonably expected to, or reasonably 
likely to, adversely affect the species or stock through effects on 
annual rates of recruitment or survival.
    Acoustic effects on marine mammals during the specified activity 
can occur from impact and vibratory pile driving and removal and DTH. 
The effects of underwater noise from ADOT&PF's proposed activities have 
the potential to result in Level A harassment and Level B harassment of 
marine mammals in the action area.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given place and is usually a composite of sound from many 
sources both near and far (American National Standards Institute 1995). 
The sound level of an area is defined by the total acoustical energy 
being generated by known and unknown sources. These sources may include 
physical (e.g., waves, wind, precipitation, earthquakes, ice, 
atmospheric sound), biological (e.g., sounds produced by marine 
mammals, fish, and invertebrates), and anthropogenic sound (e.g., 
vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al. 1995). The result is that, depending 
on the source type and its intensity, sound from the specified activity 
may be a negligible addition to the local environment or could form a 
distinctive signal that may affect marine mammals.
    In-water construction activities associated with the project would 
include impact pile driving, vibratory pile driving and removal, and 
use of DTH equipment. The sounds produced by these activities fall into 
one of two general sound types: Impulsive and non-impulsive. Impulsive 
sounds (e.g., explosions, gunshots, sonic booms, impact pile driving) 
are typically transient, brief (less than 1 second), broadband, and 
consist of high peak sound pressure with rapid rise time and rapid 
decay (ANSI 1986; National Institute of Occupational Safety and Health 
(NIOSH) 1998; NMFS 2018). Non-impulsive sounds (e.g., aircraft, 
machinery operations such as drilling or dredging, vibratory pile 
driving, and active sonar systems) can be broadband, narrowband or 
tonal, brief or prolonged (continuous or intermittent), and typically 
do not have the high peak sound pressure with rapid rise/decay time 
that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The 
distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to hearing (e.g., Ward 1997 in Southall et al. 2007).
    Three types of hammers would be used on this project: Impact, 
vibratory, and DTH. Impact hammers operate by repeatedly dropping and/
or pushing a heavy piston onto a pile to drive the pile into the 
substrate. Sound generated by impact hammers is characterized by rapid 
rise times and high peak levels, a potentially injurious combination 
(Hastings and Popper 2005). Vibratory hammers install piles by 
vibrating them and allowing the weight of the hammer to push them into 
the sediment. Vibratory hammers produce significantly less sound than 
impact hammers. Peak Sound Pressure Levels (SPLs) may be 180 dB or 
greater, but are generally 10 to 20 dB lower than SPLs generated during 
impact pile driving of the same-sized pile (Oestman et al. 2009). Rise 
time is slower, reducing the probability and severity of injury, and 
sound energy is distributed over a greater amount of time (Nedwell and 
Edwards 2002; Carlson et al. 2005).
    A DTH hammer is essentially a drill bit that drills through the 
bedrock using a rotating function like a normal drill, in concert with 
a hammering mechanism operated by a pneumatic (or sometimes hydraulic) 
component integrated into to the DTH hammer to increase speed of 
progress through the substrate (i.e., it is similar to a ``hammer 
drill'' hand tool). The sounds produced by the DTH method contain both 
a continuous, non-impulsive component from the drilling action and an 
impulsive component from the hammering effect. Therefore, we treat DTH 
systems as both impulsive and continuous, non-impulsive sound source 
types simultaneously.
    The likely or possible impacts of ADOT&PF's proposed activity on 
marine mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of the equipment and personnel; however, any impacts to marine 
mammals are expected to primarily be acoustic in nature. Acoustic 
stressors include effects of heavy equipment operation during pile 
installation and removal and DTH.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving and removal and DTH is the primary means 
by which marine mammals may be harassed from ADOT&PF's specified 
activity. In general, animals exposed to natural or anthropogenic sound 
may experience physical and psychological effects, ranging in magnitude 
from none to severe (Southall et al. 2007, 2019). In general, exposure 
to pile driving and DTH noise has the potential to result in auditory 
threshold shifts and behavioral reactions (e.g., avoidance, temporary 
cessation of foraging and vocalizing, changes in dive behavior). 
Exposure to anthropogenic noise can also lead to non-observable 
physiological responses such an increase in stress hormones. Additional 
noise in a marine mammal's habitat can mask acoustic cues used by 
marine mammals to carry out daily functions such as communication and 
predator and prey detection. The effects of pile driving and DTH noise 
on marine mammals are dependent on several factors, including, but not 
limited to, sound type (e.g., impulsive vs. non-impulsive), the 
species, age and sex class (e.g., adult male vs. mom with calf), 
duration of exposure, the distance between the pile and the animal, 
received levels, behavior at time of

[[Page 46757]]

exposure, and previous history with exposure (Wartzok et al. 2004; 
Southall et al. 2007). Here we discuss physical auditory effects 
(threshold shifts) followed by behavioral effects and potential impacts 
on habitat.
    NMFS defines a noise-induced threshold shift (TS) as a change, 
usually an increase, in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS 2018). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS (2018), there are numerous factors 
to consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
and vocalization frequency range of the exposed species relative to the 
signal's frequency spectrum (i.e., how animal uses sound within the 
frequency band of the signal; e.g., Kastelein et al. 2014), and the 
overlap between the animal and the source (e.g., spatial, temporal, and 
spectral).
    Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS 2018). Available data from 
humans and other terrestrial mammals indicate that a 40 dB threshold 
shift approximates PTS onset (see Ward et al. 1958, 1959; Ward 1960; 
Kryter et al. 1966; Miller 1974; Ahroon et al. 1996; Henderson et al. 
2008). PTS levels for marine mammals are estimates, as with the 
exception of a single study unintentionally inducing PTS in a harbor 
seal (Kastak et al. 2008), there are no empirical data measuring PTS in 
marine mammals largely due to the fact that, for various ethical 
reasons, experiments involving anthropogenic noise exposure at levels 
inducing PTS are not typically pursued or authorized (NMFS 2018).
    Temporary Threshold Shift (TTS)--A temporary, reversible increase 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS 2018). Based on data from cetacean TTS measurements (see 
Southall et al. 2007), a TTS of 6 dB is considered the minimum 
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Schlundt et 
al. 2000; Finneran et al. 2000, 2002). As described in Finneran (2015), 
marine mammal studies have shown the amount of TTS increases with 
cumulative sound exposure level (SELcum) in an accelerating fashion: At 
low exposures with lower SELcum, the amount of TTS is typically small 
and the growth curves have shallow slopes. At exposures with higher 
SELcum, the growth curves become steeper and approach linear 
relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in masking, 
below). For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that takes place during a time when the animal is traveling 
through the open ocean, where ambient noise is lower and there are not 
as many competing sounds present. Alternatively, a larger amount and 
longer duration of TTS sustained during time when communication is 
critical for successful mother/calf interactions could have more 
serious impacts. We note that reduced hearing sensitivity as a simple 
function of aging has been observed in marine mammals, as well as 
humans and other taxa (Southall et al. 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis)) and five species of pinnipeds exposed to a limited 
number of sound sources (i.e., mostly tones and octave-band noise) in 
laboratory settings (Finneran 2015). TTS was not observed in trained 
spotted (Phoca largha) and ringed (Pusa hispida) seals exposed to 
impulsive noise at levels matching previous predictions of TTS onset 
(Reichmuth et al. 2016). In general, harbor seals and harbor porpoises 
have a lower TTS onset than other measured pinniped or cetacean species 
(Finneran 2015). Additionally, the existing marine mammal TTS data come 
from a limited number of individuals within these species. No data are 
available on noise-induced hearing loss for mysticetes. For summaries 
of data on TTS in marine mammals or for further discussion of TTS onset 
thresholds, please see Southall et al. (2007), Finneran and Jenkins 
(2012), Finneran (2015), and Table 5 in NMFS (2018).
    Behavioral Harassment--Exposure to noise from pile driving and 
removal and DTH also has the potential to behaviorally disturb marine 
mammals. Available studies show wide variation in response to 
underwater sound; therefore, it is difficult to predict specifically 
how any given sound in a particular instance might affect marine 
mammals perceiving the signal. If a marine mammal does react briefly to 
an underwater sound by changing its behavior or moving a small 
distance, the impacts of the change are unlikely to be significant to 
the individual, let alone the stock or population. However, if a sound 
source displaces marine mammals from an important feeding or breeding 
area for a prolonged period, impacts on individuals and populations 
could be significant (e.g., Lusseau and Bejder 2007; Weilgart 2007; 
National Research Council (NRC) 2005).
    Disturbance may result in changing durations of surfacing and 
dives, number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); avoidance of areas where sound sources are located. 
Pinnipeds may increase their haul out time, possibly to avoid in-water 
disturbance (Thorson and Reyff 2006). Behavioral responses to sound are 
highly variable and context-specific and any reactions depend on 
numerous intrinsic and extrinsic factors (e.g., species, state of 
maturity, experience, current activity, reproductive state, auditory 
sensitivity, time of day), as well as the interplay between factors 
(e.g., Richardson et al. 1995; Wartzok et al. 2003; Southall et al. 
2007; Weilgart 2007; Archer et al. 2010). Behavioral reactions can vary 
not only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al. 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). In 
general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem

[[Page 46758]]

to be less responsive to exposure to industrial sound than most 
cetaceans. Please see Appendices B and C of Southall et al. (2007) for 
a review of studies involving marine mammal behavioral responses to 
sound.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 2007; 
Melc[oacute]n et al., 2012). In addition, behavioral state of the 
animal plays a role in the type and severity of a behavioral response, 
such as disruption to foraging (e.g., Sivle et al., 2016). A 
determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal (Goldbogen et al., 2013).
    Across 215 days between October 2020 and February 2021, May 2021 
and February 2022, and March and December 2022, ADOT&PF documented 
observations of marine mammals during construction activities (i.e., 
pile driving and removal and DTH) in Tongass Narrows (ADOT&PF 2023, 
2022, 2023). According to ADOT's monitoring reports, potential takes by 
Level B harassment of 82 Steller sea lion, 100 harbor seals, 10 Dall's 
porpoise, 60 killer whale, 33 humpback whale; and 1 elephant seal were 
recorded during pile driving or DTH. Additionally, 1 potential take by 
Level A harassment of harbor seal was recorded. While in the Level B 
harassment zones, Steller sea lions and harbor seals were identified as 
traveling, foraging, swimming, milling, looking and sinking, 
vocalizing, and resting. Steller sea lions also dived, breached, 
slapped, and chuffed while harbor seal also played, hauled out, and 
entered the water.
    Dall's porpoise and killer whales were observed milling and 
porpoising. Killer whales also swam, breached, and slapped; the 
humpback whale was observed traveling, diving, swimming, foraging, 
breaching, chuffing, milling and swimming away from in-water work. 
Given the project is a continuation of these previous activities in the 
same location, we expect similar behavioral responses of marine mammals 
to ADOT&PF's specified activity. That is, disturbance, if any, is 
likely to be temporary and localized (e.g., small area movements).
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle 1950; Moberg 
2000). In many cases, an animal's first and sometimes most economical 
(in terms of energetic costs) response is behavioral avoidance of the 
potential stressor. Autonomic nervous system responses to stress 
typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg 1987; Blecha 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al. 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al. 1996; Hood et al. 1998; Jessop et al. 2003; 
Krausman et al. 2004; Lankford et al. 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker 2000; Romano 
et al. 2002b) and, more rarely, studied in wild populations (e.g., 
Romano et al. 2002a). For example, Rolland et al. (2012) found that 
noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC 2003), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar projects in the area.
    Masking--Sound can disrupt behavior through masking, or interfering 
with, an animal's ability to detect, recognize, or discriminate between 
acoustic signals of interest (e.g., those used for intraspecific 
communication and social interactions, prey detection, predator 
avoidance, navigation) (Richardson et al. 1995). Masking occurs when 
the receipt of a sound is interfered with by another coincident sound 
at similar frequencies and at similar or higher intensity, and may 
occur whether the sound is natural (e.g., snapping shrimp, wind, waves, 
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar, 
seismic exploration) in origin. The ability of a noise source to mask 
biologically important sounds depends on the characteristics of both 
the noise source and the signal of interest (e.g., signal-to-noise 
ratio, temporal variability, direction), in relation to each other and 
to an animal's hearing abilities (e.g., sensitivity, frequency range, 
critical ratios, frequency discrimination, directional discrimination, 
age or TTS hearing loss), and existing ambient noise and propagation 
conditions. Masking of natural sounds can result when human activities 
produce high levels of background sound at frequencies important to 
marine mammals. Conversely, if the background level of underwater sound 
is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked.
    Airborne Acoustic Effects--Airborne noise would primarily be an 
issue for pinnipeds that are swimming or hauled out near the project 
site within the range

[[Page 46759]]

of noise levels elevated above the acoustic criteria. We recognize that 
pinnipeds in the water could be exposed to airborne sound that may 
result in behavioral harassment when looking with their heads above 
water. Most likely, airborne sound would cause behavioral responses 
similar to those discussed above in relation to underwater sound. For 
instance, anthropogenic sound could cause hauled-out pinnipeds to 
exhibit changes in their normal behavior, such as reduction in 
vocalizations, or cause them to temporarily abandon the area and move 
further from the source. However, these animals would previously have 
been ``taken'' because of exposure to underwater sound above the 
behavioral harassment thresholds, which are in all cases larger than 
those associated with airborne sound. Thus, the behavioral harassment 
of these animals is already accounted for in these estimates of 
potential take. Therefore, we do not believe that authorization of 
incidental take resulting from airborne sound for pinnipeds is 
warranted, and airborne sound is not discussed further. Cetaceans are 
not expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA.

Marine Mammal Habitat Effects

    ADOT&PF 's proposed activities at the project area would not result 
in permanent negative impacts to habitats used directly by marine 
mammals, but may have potential short-term impacts to food sources such 
as forage fish and may affect acoustic habitat (see masking discussion 
above). ADOT&PF's construction activities in Tongass Narrows could have 
localized, temporary impacts on marine mammal habitat and their prey by 
increasing in-water sound pressure levels and slightly decreasing water 
quality. Increased noise levels may affect acoustic habitat (see 
masking discussion above) and adversely affect marine mammal prey in 
the vicinity of the project area (see discussion below). During DTH, 
impact and vibratory pile driving or removal, elevated levels of 
underwater noise would ensonify a portion of Tongass Narrows and nearby 
waters where both fishes and mammals occur and could affect foraging 
success. Additionally, marine mammals may avoid the area during 
construction, however, displacement due to noise is expected to be 
temporary and is not expected to result in long-term effects to the 
individuals or populations. Construction activities are of short 
duration and would likely have temporary impacts on marine mammal 
habitat through increases in underwater and airborne sound.
    The area likely impacted by the project includes much of Tongass 
Narrows, but overall this area is relatively small compared to the 
available habitat in the surrounding area including Revillagigedo 
Channel, Behm Canal, and Clarence Strait. Pile installation/removal and 
DTH may temporarily increase turbidity resulting from suspended 
sediments. Any increases would be temporary, localized, and minimal. In 
general, turbidity associated with pile installation is localized to 
about a 25-ft radius around the pile (Everitt et al. 1980). Cetaceans 
are not expected to be close enough to the project pile driving areas 
to experience effects of turbidity, and pinnipeds could avoid localized 
areas of turbidity. Therefore, the impact from increased turbidity 
levels is expected to minimal for marine mammals. Furthermore, pile 
driving and removal at the project site would not obstruct movements or 
migration of marine mammals.
    In-water Construction Effects on Potential Prey--Construction 
activities would produce continuous (i.e., vibratory pile driving and 
DTH) and intermittent (i.e., impact driving and DTH) sounds. Sound may 
affect marine mammals through impacts on the abundance, behavior, or 
distribution of prey species (e.g., crustaceans, cephalopods, fish, 
zooplankton). Marine mammal prey varies by species, season, and 
location. Here, we describe studies regarding the effects of noise on 
known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick and Mann 1999; Fay 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al. 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds that are especially strong and/or intermittent 
low-frequency sounds. Short duration, sharp sounds can cause overt or 
subtle changes in fish behavior and local distribution. The reaction of 
fish to noise depends on the physiological state of the fish, past 
exposures, motivation (e.g., feeding, spawning, migration), and other 
environmental factors. Hastings and Popper (2005) identified several 
studies that suggest fish may relocate to avoid certain areas of sound 
energy. Additional studies have documented effects of pile driving on 
fish; several are based on studies in support of large, multiyear 
bridge construction projects (e.g., Scholik and Yan 2001, 2002; Popper 
and Hastings 2009). Several studies have demonstrated that impulse 
sounds might affect the distribution and behavior of some fishes, 
potentially impacting foraging opportunities or increasing energetic 
costs (e.g., Fewtrell and McCauley, 2012; Pearson et al. 1992; Skalski 
et al. 1992; Santulli et al. 1999; Paxton et al. 2017). However, some 
studies have shown no or slight reaction to impulse sounds (e.g., Pena 
et al. 2013; Wardle et al. 2001; Jorgenson and Gyselman, 2009; Cott et 
al. 2012).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al. 2012b; Casper et al. 2013).
    The most likely impact to fish from pile driving and removal and 
DTH activities at the project area would be temporary behavioral 
avoidance of the area. The duration of fish avoidance of this area 
after pile driving stops is unknown, but a rapid return to normal 
recruitment, distribution and behavior is anticipated. Any behavioral 
avoidance by fish of the disturbed area would still leave significantly 
large areas of fish and marine mammal foraging habitat in the nearby 
vicinity in Revillagigedo Channel, Behm Canal, and Clarence Strait. 
Additionally, the COK is within Tongass Narrows and has a busy 
industrial water front, and human impact lessens the value of the area 
as foraging habitat. There are times of known seasonal marine mammal 
foraging in Tongass Narrows around fish

[[Page 46760]]

processing/hatchery infrastructure or when fish are congregating, but 
the impacted areas of Tongass Narrows are a small portion of the total 
foraging habitat available in the region. In general, impacts to marine 
mammal prey species are expected to be minor and temporary due to the 
short timeframe of the project.
    Construction activities, in the form of increased turbidity, have 
the potential to adversely affect eulachon, herring, and juvenile 
salmonid migratory routes in the project area. Salmon and forage fish, 
like eulachon and herring, form a significant prey base for Steller sea 
lions and are major components of the diet of many other marine mammal 
species that occur in the project area. Increased turbidity is expected 
to occur only in the immediate vicinity of construction activities and 
to dissipate quickly with tidal cycles. Given the limited area affected 
and high tidal dilution rates any effects on fish are expected to be 
minor.
    Additionally, the presence of transient killer whales means some 
marine mammal species are also possible prey (harbor seals, harbor 
porpoises). ADOT&PF's pile driving, pile removal and DTH activities are 
expected to result in limited instances of take by Level B harassment 
and Level A harassment on these smaller marine mammals. That, as well 
as the fact that ADOT&PF is impacting a small portion of the total 
available marine mammal habitat means that there would be minimal 
impact on these marine mammals as prey.
    In summary, given the short daily duration of sound associated with 
individual pile driving and DTH events and the small area being 
affected relative to available nearby habitat, pile driving and DTH 
activities associated with the proposed action are not likely to have a 
permanent, adverse effect on any fish habitat, or populations of fish 
species or other prey. Thus, we conclude that impacts of the specified 
activity are not likely to have more than short-term adverse effects on 
any prey habitat or populations of prey species. Further, any impacts 
to marine mammal habitat are not expected to result in significant or 
long-term consequences for individual marine mammals, or to contribute 
to adverse impacts on their populations.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., impact and vibratory pile driving and 
removal and DTH) has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result, primarily 
for high frequency cetaceans, phocids, and otariids because predicted 
auditory injury zones are larger than for other hearing groups. 
Auditory injury is unlikely to occur for other groups. The proposed 
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 proposed to be authorized for this activity. Below we 
describe how the proposed take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the proposed take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile 
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., impact pile driving) or intermittent (e.g., 
scientific sonar) sources. This take estimation includes disruption of 
behavioral patterns resulting directly in response to noise exposure 
(e.g., avoidance), as well as the resulting indirectly form the 
associated impacts such as TTS or masking. ADOT&PF's proposed activity 
includes the use of continuous (vibratory pile driving/removal and DTH) 
and impulsive (impact pile driving and DTH) sources, and therefore the 
RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are applicable.
    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). ADOT&PF's 
proposed activity includes the use of impulsive (impact pile driving 
and DTH) and non-impulsive (vibratory pile driving/removal and DTH) 
sources.

[[Page 46761]]

    These thresholds are provided in Table 4 below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
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 thresholds \*\ (received level)
            Hearing group             --------------------------------------------------------------------------
                                              Impulsive                           Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans.........  Cell 1: L0-pk,flat: 219  Cell 2: LE,LF,24h: 199 dB.
                                        dB; LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans.........  Cell 3: L0-pk,flat: 230  Cell 4: LE,MF,24h: 198 dB.
                                        dB; LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans........  Cell 5: L0-pk,flat: 202  Cell 6: LE,HF,24h: 173 dB.
                                        dB; LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)...  Cell 7: L0-pk,flat: 218  Cell 8: LE,PW,24h: 201 dB.
                                        dB; LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)..  Cell 9: L0-pk,flat: 232  Cell 10: LE,OW,24h: 219 dB.
                                        dB; LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS
  onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds
  associated with impulsive sounds, these thresholds are recommended for consideration.
Note: Peak sound pressure level (L0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
  exposure level (LE,) has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to be
  more reflective of International Organization for Standardization standards (ISO 2017). The subscript ``flat''
  is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized
  hearing range of marine mammals (i.e., 7 Hz to 160 kHz). The subscript associated with cumulative sound
  exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF
  cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The weighted
  cumulative sound exposure level thresholds could be exceeded in a multitude of ways (i.e., varying exposure
  levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the
  conditions under which these thresholds will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact pile driving, vibratory 
pile driving and removal, and DTH).
    The intensity of pile driving sounds is greatly influenced by 
factors such as the type of piles (material and diameter), hammer type, 
and the physical environment (e.g., sediment type) in which the 
activity takes place. The ADOT&PF evaluated SPL measurements available 
for certain pile types and sizes from similar activities elsewhere to 
determine appropriate proxy levels for their proposed activities. The 
ADOT&PF also initially referred to preliminary results from a sound 
source verification study to determine SPLs for DTH of 8-inch tension 
anchors and Transmission Loss values (TLs) for all DTH activities. As 
discussed in the Summary of Request section above, a Sound Source 
Verification (SSV) report detailing sound source values and TL 
coefficients collected at the project site was subsequently submitted.
    To determine appropriate proxy SPLs for impact and vibratory pile 
driving of all pile types, NMFS completed a comprehensive review of 
source levels relevant to Southeast Alaska to generate regionally-
specific source levels. NMFS compiled all available data from Puget 
Sound and Southeast Alaska and adjusted the data to standardize 
distance from the measured pile to 10 m.. NMFS then calculated average 
source levels for each project and for each pile type. NMFS weighted 
impact pile driving project averages by the number of strikes per pile 
following the methodology in Navy (2015). The source levels for these 
various pile types, sizes and methods are listed in Table 5. 
Additionally, ADOT&PF requested, and NMFS agreed, to use the 24-inch 
sound source values for impact or vibratory pile driving of 14-inch H-
piles, because the source value of smaller piles of the same general 
type (steel) are not expected to exceed a larger pile.
    NMFS recommends treating DTH systems as both impulsive and 
continuous, non-impulsive sound source types simultaneously. Thus, 
impulsive thresholds are used to evaluate Level A harassment, and 
continuous thresholds are used to evaluate Level B harassment. NMFS 
(2022) recommended guidance on DTH systems (https://media.fisheries.noaa.gov/2022-11/PUBLIC%20DTH%20Basic%20Guidance_November%202022.pdf) outlines its 
recommended source levels for DTH systems. NMFS has applied that 
guidance in this analysis (see Table 5 for NMFS' proposed source 
levels). Note that the values in this table represent the SPL 
referenced to a distance of 10 m (33 ft) from the source.
    TL is the decrease in acoustic intensity as an acoustic pressure 
wave propagates out from a source. TL parameters vary with frequency, 
temperature, sea conditions, current, source and receiver depth, water 
depth, water chemistry, and bottom composition and topography. The 
general formula for underwater TL is:

TL = B*Log10(R1/R2),

Where:

TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement

    Absent site-specific acoustical monitoring with differing measured 
transmission loss, a practical spreading value of 15 is used as the 
transmission loss coefficient in the above formula. Site-specific 
transmission loss data for the Tongass Narrows are not available for 
vibratory pile installation and removal and impact pile driving; 
therefore, the default coefficient of 15 is used to determine the 
distances to the Level A harassment and Level B harassment thresholds 
for these activities and associated pile types. In the case of DTH 
activities, ADOT&PF conducted SSV at the project site for DTH of 24-
inch rock sockets and 8-inch tension anchors. NMFS reviewed the TL data 
from this monitoring and has incorporated the most conservative 
transmission loss values measured for each pile type at the project 
site in its analysis herein (Table 5).

[[Page 46762]]



Table 5--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, DTH,
                                           and Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
                                                SELss (dB re 1
                                RMS SPL (dB re   [micro]Pa\2\    Peak SPL (dB      References     TL coefficient
                                  1 [micro]Pa)       sec)            re 1          levels (TL)          \1\
                                                                  [micro]Pa)
----------------------------------------------------------------------------------------------------------------
                                                Vibratory Hammer
----------------------------------------------------------------------------------------------------------------
30-inch steel piles...........             166              NA              NA  NMFS Analysis--               15
                                                                                 C. Hotchkin
                                                                                 April 24, 2023.
24-inch steel piles...........             163              NA              NA  NMFS Analysis--               15
                                                                                 C. Hotchkin
                                                                                 April 24, 2023.
Steel 14'' H-piles \3\........             163              NA              NA  24-inch as proxy              15
----------------------------------------------------------------------------------------------------------------
                               DTH of Rock Sockets and Tension Anchors--Continuous
----------------------------------------------------------------------------------------------------------------
24-inch (Rock Socket).........             167              NA              NA  Heyvaert & Reyff            19.5
                                                                                 2021; (Reyff
                                                                                 and Ambaskar
                                                                                 2023).
8-inch DTH (Tension Anchor)...             156              NA              NA  Reyff & Heyvaert            17.1
                                                                                 2019; Reyff
                                                                                 2020; (Reyff
                                                                                 and Ambaskar
                                                                                 2023).
----------------------------------------------------------------------------------------------------------------
                                                  Impact Hammer
----------------------------------------------------------------------------------------------------------------
30-inch steel piles...........             195             183             210  NMFS Analysis--               15
                                                                                 C. Hotchkin
                                                                                 April 24, 2023.
24-inch steel piles...........             190             177             203  Caltrans 2015,                15
                                                                                 Caltrans 2020.
Steel 14'' H-piles \2\........             190             177             203  24-inch as proxy              15
----------------------------------------------------------------------------------------------------------------
                               DTH of rock sockets and tension anchors--Impulsive
----------------------------------------------------------------------------------------------------------------
24-inch (Rock Socket).........              NA             159             184  Heyvaert & Reyff            19.9
                                                                                 2021; (Reyff
                                                                                 and Ambaskar
                                                                                 2023).
8-inch (Tension anchor).......              NA             144             170  Reyff 2020;                 17.1
                                                                                 (Reyff and
                                                                                 Ambaskar 2023).
----------------------------------------------------------------------------------------------------------------
\1\ NMFS recommends a default transmission loss of 15*log10(R) when site-specific data are not available (NMFS,
  2020; NMFS, 2022).
\2\ For 14-inch H piles, NMFS uses sound source level data from 24-inch piles as a conservative proxy.
Note: all SPLs are unattenuated and represent the SPL referenced to a distance of 10 m from the source; NA = Not
  applicable; dB re 1 [micro]Pa = decibels (dB) referenced to a pressure of 1 microPascal, measures underwater
  SPL; dB re 1 [micro]Pa2-sec = dB referenced to a pressure of 1 microPascal squared per second, measures
  underwater SEL.

    All Level B harassment isopleths are reported in Table 6 below. Of 
note, based on the geography of Tongass Narrows and the surrounding 
islands, sound would not reach the full distance of the Level B 
harassment isopleth in most directions. Generally, due to interaction 
with land, only a thin slice of the possible area would be ensonified 
to the full distance of the Level B harassment isopleth.

     Table 6--Level B Harassment Isopleths by Activity and Pile Size
------------------------------------------------------------------------
                                                              Level B
                Activity                   Pile diameter    harassment
                                              (inch)       isopleth (m)
------------------------------------------------------------------------
Vibratory Installation and Removal......              30          11,659
                                                      24           7,365
                                                      14
DTH Rock Sockets........................              24           2,572
DTH Tension Anchor......................               8           1,274
Impact Installation.....................              30           2,154
                                                      24           1,000
                                                      14
------------------------------------------------------------------------

    The ensonified area associated with Level A harassment is more 
technically challenging to predict due to the need to account for a 
duration component. Therefore, NMFS developed an optional User 
Spreadsheet tool to accompany the Technical Guidance that can be used 
to relatively simply predict an isopleth distance for use in 
conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources such as pile driving or removal or DTH using any of 
the methods discussed above, the optional User Spreadsheet tool 
predicts the distance at which, if a marine mammal remained at that 
distance for the duration of the activity, it would be expected to 
incur

[[Page 46763]]

PTS. Inputs used in the optional User Spreadsheet tool, and the 
resulting estimated isopleths, are reported in Table 7 and Table 8.

                                                          Table 7--NMFS User Spreadsheet Inputs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Vibratory pile driving                            DTH                                   Impact
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     30-inch steel       24-inch steel     Rock socket (24-   Tension anchor (8-     30-inch steel       24-inch steel
---------------------------------        piles         piles or steel H-         inch)               inch)               piles         piles or steel H-
                                 --------------------        pile        ------------------------------------------------------------        pile
                                                     --------------------                                                            -------------------
                                    Installation or     Installation or      Installation        Installation        Installation
                                        removal             removal                                                                      Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used............  A.1) Vibratory      A.1) Vibratory      E.2) DTH Pile       E.2) DTH Pile       E.1) Impact Pile    E.1) Impact Pile
                                   Pile Driving.       Pile Driving.       Driving.            Driving.            Driving.            Driving.
Source Level (SPL)..............  166 RMS...........  163 RMS...........  167 RMS, 159 SEL..  156 RMS, 144 SEL..  183 SEL...........  177 SEL.
Transmission Loss Coefficient...  15................  15................  19.5, 19.9........  17.1, 17.1........  15................  15.
Weighting Factor Adjustment       2.5...............  2.5...............  2.................  2.................  2.................  2.
 (kHz).
Activity Duration (hours) within  *0.5-6............  *0.5-8............  1-8...............  1-8.
 24 hours.
Strike rate strike per second...  ..................  ..................  10................  19.
Number of strikes per pile......  ..................  ..................  ..................  ..................  50 (temporary);     50 (temporary);
                                                                                                                   200 (permanent).    200 (permanent).
Number of piles per day.........  1-6...............  1-8...............  1.................  1.................  1-3...............  1-3.
Distance of sound pressure level  10................  10................  10................  10................  10................  10.
 measurement.
--------------------------------------------------------------------------------------------------------------------------------------------------------
*A range of activity durations (vibratory and DTH), strikes per pile (impact), piles per day are listed because ADOT&PF anticipates that they can
  install or remove piles of the same size at different rates at different sites. Duration estimates for DTH assume that multiple rock sockets and
  tension anchors would be installed each day, with a maximum daily duration of 8 hours.

    Level A harassment thresholds for impulsive sound sources (impact 
pile driving and DTH) are defined for both SELcum and Peak SPL with the 
threshold that results in the largest modeled isopleth for each marine 
mammal hearing group used to establish the Level A harassment isopleth. 
In this project, Level A harassment isopleths based on SELcum were 
always larger than those based on Peak SPL. It should be noted that 
there is a duration component when calculating the Level A harassment 
isopleth based on SELcum, and this duration depends on the number of 
piles that would be driven in a day and strikes per pile. For some 
activities, ADOT&PF has proposed to drive variable numbers of piles per 
day throughout the project (See ``Average Piles per Day (Range)'' in 
Table 1). NMFS accounted for this variability in its analysis. For each 
activity, ADOT&PF provided the minimum and maximum potential durations 
of the activity. In some cases the difference in the Level A harassment 
zone size between the minimum and maximum duration anticipated for an 
activity for a given hearing group is quite large. ADOT&PF expressed 
concerns about implementing the largest Level A harassment zones for an 
activity on days where activity levels would be much lower, 
particularly given that the shutdown zones for an activity (Table 10) 
are based upon the Level A harassment zone sizes. Therefore, for low 
frequency cetaceans and phocids, in order to provide flexibility while 
ensuring the number of Level A harassment zones and associated shutdown 
zones are manageable, NMFS proposes two Level A harassment isopleths 
for a given activity in cases where the differences between zone sizes 
associated with the minimum and maximum potential activity duration 
spans >=100 m. At the beginning of each pile driving day, ADOT&PF would 
determine the maximum number or duration that piles would be driven 
that day and implement the Level A harassment zone associated with that 
amount of activity.

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

[[Page 46764]]

 
Impact, 200 strikes.........................  30................................               1           542.1            25.3           846.2           182.8            27.7           2,154
                                                                                               2                                                           380.2
                                                                                               3           710.4
                                              24 or 14..........................               1           136.0            10.1           336.9            72.8            11.0           1,000
                                                                                               2           282.8                                           151.4
                                                                                               3
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Impact, 50 strikes..........................  24 or 14..........................             1-3           112.2             4.0           133.7            60.1             4.4           1,000
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* For low frequency cetaceans and phocids, in cases where the Level A harassment zone spanned >=100 m between the minimum and maximum duration for the same activity, NMFS analyzed a shorter
  activity duration to allow for flexibility.

Marine Mammal Occurrence and Take Estimation

    In this section we provide information about the occurrence of 
marine mammals, including density, or group dynamics of marine mammals, 
that will inform the take calculations. Additionally, we describe how 
the occurrence information is synthesized to produce a quantitative 
estimate of the take that is reasonably likely to occur and proposed 
for authorization. Note that take estimates included in ADOT&PF's 
application reflect 152 construction days rather than 131 (see Summary 
of Request section, in which it is described that one site has been 
completed since submission of the application). A summary of proposed 
take, including a percentage of population for each of the species, is 
shown in Table 9.
Minke Whale
    There are no known occurrences of minke whales within the project 
area. No minke whales where reported during ADOT&PF's previous 
construction activities at the project site (ADOT&PF 2021, 2023), nor 
during other recent projects in the Tongass Narrows (e.g., COK Rock 
Pinnacle Blasting Project, Sitkiewicz 2020, Ward Cove Cruise Ship Dock 
in 2020, Power Systems and Supplies of Alaska, 2020). However, since 
their range extends into the project area, and they have been observed 
in southeast Alaska, including in Clarence Strait (Dahlheim et al., 
2009), it is possible the species could occur in the project area. 
Still, future observations of minke whale in the project area are 
expected to be rare.
    ADOT&PF conservatively requested take by Level B harassment of 
three minke whales every 4 months across the 12 months that the IHA is 
active. NMFS concurs with ADOT&PF's estimated group size and frequency, 
but finds it more appropriate to estimate take according to the number 
of actual months in which construction is proposed. As such, NMFS 
conservatively proposes to authorize four takes by Level B harassment 
(3 minke whales x 1.25 months = 4 takes by Level B harassment).
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, especially in combination with the infrequent 
occurrence of minke whales entering the project area, implementation of 
the proposed shutdown zones is expected to eliminate the potential for 
take by Level A harassment of minke whale. Therefore, ADOT&PF did not 
request take by Level A harassment of minke whale, nor is NMFS is 
proposing to authorize any.
Fin Whale
    Fin whales typically inhabit deep, offshore waters and often travel 
in open seas away from coasts, and are often observed in social groups 
of two to seven. However, a single fin whale was recently observed in 
Clarence Strait (Scheurer, personal communication). Since the 
ensonified area extends to the mouth of Tongass Narrows, where it meets 
Clarence Strait, there is a chance that fin whale could occur in the 
project area during construction. As such, NMFS conservatively proposes 
to authorize two takes by Level B harassment of fin whale.
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, especially given the rare occurrence of fin 
whale in the surrounding area, implementation of the proposed shutdown 
zones is expected to eliminate the potential for take by Level A 
harassment of fin whale. Therefore, ADOT&PF did not request take by 
Level A harassment of fin whale, nor is NMFS is proposing to authorize 
any.
Humpback Whale
    While no systematic studies have documented humpback whale 
abundance near Ketchikan, anecdotal information suggests that this 
species is present in low numbers year-round in Tongass Narrows. 
Additionally, during ADOT&PF's 215 days of monitoring associated with 
previous construction, 80 humpback whales were observed, or 0.37 
humpback whales per day (ADOT&PF 2021, 2023). According to ADOT&PF, the 
average group size was 1.25 humpback whales, and the maximum group size 
was 4.
    ADOT&PF conservatively estimates, and NMFS concurs, that one 
humpback whale may occur in the Level B harassment zone each day of 
proposed in-water work (1 humpback whale x 131 days = 131 takes by 
Level B harassment).
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, implementation of the proposed shutdown zones is 
expected to eliminate the potential for take by Level A harassment of 
humpback whale. Therefore, ADOT&PF did not request take by Level A 
harassment of humpback whale, nor is NMFS is proposing to authorize 
any.
Gray Whale
    Gray whales are rare in the project area and unlikely to occur in 
Tongass Narrows. They were not observed during the Dahlheim et al. 
(2009)

[[Page 46765]]

surveys of Alaska's inland waters with surveys conducted in the spring, 
summer and fall months. No gray whales where reported during ADOT&PF's 
previous construction activities at the project site (ADOT&PF 2021, 
2023), nor during other recent projects in the Tongass Narrows (e.g., 
COK Rock Pinnacle Blasting Project, Sitkiewicz 2020; Ward Cove Cruise 
Ship Dock in 2020, Power Systems and Supplies of Alaska, 2020). However 
a gray whale could migrate through or near the project, during November 
especially. Gray whales are generally solitary and travel together, 
alone, or in small groups.
    ADOT&PF requested 24 takes by Level B harassment of gray whales (1 
group x 2 gray whales x 12 months that the IHA is active). NMFS concurs 
with ADOT&PF's estimated group size and frequency, but finds it more 
appropriate to base take estimates on proposed duration of in-water 
work. As such, NMFS proposes to authorize 10 takes by Level B 
harassment (1 group x 2 gray whales x 5 months = 10 takes by Level B 
harassment).
    ADOT&PF is planning to implement shutdown zones for low-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Therefore, especially in combination with the low 
occurrence of gray whales in the project area, implementation of the 
proposed shutdown zones is expected to eliminate the potential for take 
by Level A harassment of gray whale. Therefore, ADOT&PF did not request 
take by Level A harassment of gray whale, nor is NMFS is proposing to 
authorize any.
Pacific White-Sided Dolphin
    Pacific white-sided dolphins were not observed during the 215 days 
of marine mammal monitoring associated with ADOT&PF's previous 
construction activities at this site (ADOT&PF 2021, 2023). There were 
also no sightings of Pacific white-sided dolphins during previous 
monitoring conducted during other recent construction projects in the 
Tongass Narrows (Sitkiewicz 2020, Power Systems and Supplies of Alaska, 
2020).
    While rare in the inside passageways of Southeast Alaska, a group 
of 164 Pacific white-sided dolphins were observed in the Dixon entrance 
to the south of Tongass Narrows during aerial surveys in 1997 (Muto et 
al. 2018), and this species was also documented in Revillagigedo 
Channel, Behm Canal, and Clarence Strait during surveys conducted from 
April to May between 1991 and 1993 (Dahlheim and Towell 1994). Finally, 
Dalheim et al. (2009) frequently encountered Pacific white-sided 
dolphins in Clarence Strait. Observations were noted most typically in 
open strait environments, near the open ocean. Mean group size was over 
20, with no recorded winter observations nor observations made in the 
Nichols Passage or Behm Canal, located on either side of the Tongass 
Narrows. This observational data, combined with anecdotal information, 
indicates that while Pacific white-sided dolphins are rare in the area, 
they could occur in the project area during construction.
    ADOT&PF requested Level B harassment take of one group of 50 
Pacific white-sided dolphins. However, to remain consistent with mean 
groups sizes detected near Tongass Narrows (Dalheim et al., 2009), NMFS 
finds it more appropriate to propose to authorize three groups of 20 
pacific white sided dolphins (60 takes by Level B harassment of Pacific 
white-sided dolphin).
    ADOT&PF is planning to implement shutdown zones for mid-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Additionally, the Level A harassment isopleths for mid-
frequency cetaceans are quite small, and therefore, shutdown zones 
should be easily implemented. Therefore, especially in combination with 
the low occurrence of pacific white-sided dolphins in the project area, 
implementation of the proposed shutdown zones is expected to eliminate 
the potential for take by Level A harassment of Pacific white-sided 
dolphin. Therefore, ADOT&PF did not request take by Level A harassment 
of Pacific white-sided dolphin, nor is NMFS is proposing to authorize 
any..
Killer Whale
    While no systematic studies of killer whales have been conducted in 
or around Tongass Narrows, killer whales are observed in Tongass 
Narrows year-round, and anecdotal reports suggest they are most common 
during the summer Chinook salmon run (May-July) (84 FR 36891, July 30, 
2019). Across the 215 days of monitoring during ADOT&PF's previous 
Tongass Narrows construction activities, a total of 78 killer whales 
were observed, for an observation rate of 0.36 per day (ADOT&PF 2021, 
2023). According to ADOT&PF, the average group size observed was 4.6 
killer whales and the maximum group size was 8.
    While ADOT&PF requested 180 takes by Level B harassment [(1 group x 
12 killer whales x 9 months) + (2 groups x 12 killer whales x 3 months 
= 180 takes by Level B harassment)], NMFS finds it more appropriate to 
base take estimates off the maximum group size (8 killer whales) 
observed during monitoring of previous construction activities and the 
proposed duration of in-water work (5 months). As such, NMFS proposes 
to authorize 64 takes by Level B harassment ([(2 pods x 8 killer whales 
x 3 months) + (1 pod x 8 killer whales x 2 months) = 64 takes by Level 
B harassment)].
    ADOT&PF is planning to implement shutdown zones for mid-frequency 
cetaceans that exceed the Level A harassment isopleth for all 
activities. Additionally, the Level A harassment isopleths for mid-
frequency cetaceans are quite small and therefore shutdown zones should 
be easily implemented. Therefore, implementation of the proposed 
shutdown zones is expected to eliminate the potential for take by Level 
A harassment of killer whale. Therefore, ADOT&PF did not request take 
by Level A harassment of killer whale, nor is NMFS is proposing to 
authorize any.
Harbor Porpoise
    Abundance data for harbor porpoise in Southeast Alaska were 
collected during 18 seasonal surveys spanning 22 years, from 1991 to 
2012 (Dahlheim et al. 2015). The project area falls within the Clarence 
Strait to Ketchikan region, as identified by this study for the survey 
effort. Harbor porpoise densities in this region in summer were low, 
ranging from 0.01 to 0.02 harbor porpoises/kilometers\2\. During 
ADOT&PF's 215 days of monitoring during previous construction 
activities at this project site, the daily average observations of 
harbor porpoise in the project area was 0.1 (ADOT&PF 2021, 2023). 
According to ADOT&PF, the maximum group size observed during this 
monitoring was five.
    ADOT&PF estimates that two groups of five harbor porpoise may occur 
in the Level B harassment zone across the 12 months that the IHA is 
active. NMFS concurs with ADOT&PF's estimated group size but finds it 
appropriate to increase the frequency of occurrence estimate in the 
Level B harassment zone from two groups per month to three groups per 
month of work. Additionally, NMFS finds it more appropriate to estimate 
take by Level B harassment according to proposed duration of in-water 
work (3 groups x 5 harbor porpoises x 5 months = 75 takes by Level B 
harassment). Additionally, ADOT&PF requested take by Level A harassment 
of one group of five harbor porpoise every 4 months across 12 months 
that the IHA is active. However, NMFS finds it more appropriate to 
estimate take by Level A harassment

[[Page 46766]]

according to the number of months in which the Level A harassment zone 
may extend beyond the proposed shutdown zone (i.e., 2.9 months, when 
DTH systems may be employed to install 24-inch piles, or 24-inch and 
30-inch piles may be installed with an impact pile driver (200 
strikes)]. As such, NMFS proposes to authorize 15 takes by Level A 
harassment of harbor porpoise (1 group x 5 harbor porpoise x 2.9 months 
= 15 takes by Level B harassment) and 60 takes by Level B harassment 
((3 groups x 5 harbor porpoise x 5 months)-15 takes by Level A 
harassment = 60 takes by Level B harassment).
Dall's Porpoise
    Dall's porpoise have occasionally been observed during previous 
construction projects completed in Tongass Narrows (Power Systems and 
Supplies of Alaska, 2020), including during ADOT&PF's 215 days of 
monitoring (ADOT&PF 2021, 2023). ADOT&PF reported that the average 
group size observed was 5.6 and the maximum group size was 10. To 
estimate take, ADOT&PF has assumed that Dall's porpoise may occur in 
pods of 15 and across the 12 months that the IHA is active. NMFS finds 
it more appropriate to base take estimates off the maximum group size 
(10 Dall's porpoise) observed during monitoring of previous 
construction activities and according to estimated duration of proposed 
pile driving and DTH activities.
    As such, while ADOT estimates that one pod of 15 Dall's porpoise 
may occur within the Level B harassment zone across each of the 12 
months that the IHA would be active, NMFS finds it more appropriate to 
conservatively estimates that two pods of 10 Dall's porpoise may occur 
in the Level B harassment zone each month in which in-water work is 
proposed (2 pod x 10 Dall's porpoise x 5 months = 100).
    Additionally, ADOT&PF has estimated that one pod of 15 Dall's 
porpoise may occur within the Level A harassment zone across the 12 
months that the IHA would be active. However, NMFS finds it more 
appropriate to estimate 10 takes by Level A harassment of Dall's 
porpoise across the 2.9 months in which the Level A harassment zone may 
extend beyond the shutdown zone for this species, which could occur 
when DTH systems are employed to install 24-inch piles or an impact 
pile driver (200 strikes) is used to install 24-inch and 30-inch piles 
(1 group x 10 Dall's porpoise = 10 takes by Level A harassment). 
Finally, take by Level B harassment proposed for authorization has been 
calculated as the total calculated Dall's porpoise takes by Level B 
harassment minus the takes by Level A harassment (100 takes by Level B 
harassment-10 takes by Level A harassment = 90 takes by Level B 
harassment).
Steller Sea Lion
    Steller sea lions may be found in Tongass Narrows year-round, with 
anecdotal reports suggesting an increase in abundance from March to 
early May during the herring spawning season, and another increase in 
late summer associated with salmon runs. During the 215 days of marine 
mammal monitoring that took place during construction of previous 
components of the Tongass Narrows Project, a total of 322 Steller sea 
lions were observed (ADOT&PF 2021, 2023). According to ADOT&PF, the 
average group size was 1.25 individuals and maximum group size observed 
was five individuals. At least one Steller sea lion was observed during 
each month that monitoring took place. Monitoring during construction 
of the nearby Ward Cove Dock recorded 4.1 individuals per day (Power 
Systems & Supplies of Alaska, 2020).
    ADOT&PF estimates that one group of 10 Steller sea lions may be 
taken by Level B harassment each day that in-water work is proposed. 
Based on ADOT&PF's 215 days of project-related monitoring, NMFS finds 
it more appropriate to estimate that one group of five Steller sea 
lions may be present in the Level B harassment zone each day (1 group x 
5 Steller sea lion x 131 construction days = 655 takes by Level B 
harassment).
    ADOT&PF is required to implement a shutdown zone that exceeds the 
Level A harassment zone for Steller sea lions during all project 
activities. However, ADOT&PF expects that Steller sea lions could enter 
the Level A harassment zone undetected on rare occasions. As such, 
ADOT&PF requests take by Level A harassment of 5 percent of Steller sea 
lions authorized for take by Level B harassment. NMFS concurs that, 
given the various structures along the shoreline in the project area, 
Steller sea lions could enter the Level A harassment zone and remain in 
the zone undetected for a long enough duration to incur PTS before a 
shutdown occurs. However, NMFS anticipates that 5 percent of the take 
by Level B harassment would result in an overestimate of Level A 
harassment. NMFS anticipates that10 Steller sea lions could enter the 
Level A harassment zone and remain in the zone undetected for a long 
enough duration to incur PTS before a shutdown occurs across the 131 
days of proposed in-water work. As such, NMFS proposes to authorize 10 
takes by Level A harassment and 645 takes by Level B harassment (1 
group x 5 individuals x 131 construction days-10 takes by Level A 
harassment = 645 takes by Level B harassment).
Northern Elephant Seal
    Although northern elephant seals are known to visit the Gulf of 
Alaska to feed on benthic prey, they rarely occur on the beaches of 
Alaska. Despite the low probability of northern elephant seals entering 
the project area, there have been recent reports of elephant seals 
occurring in and near the Tongass Narrows, and two northern elephant 
seals were observed during ADOT&PF's Tongass Narrows construction in 
2022. As such, ADOT&PF requests take by Level B harassment of one 
elephant seal per 6-day work week. NMFS concurs that one take by Level 
B harassment per work week is appropriate. However, because ADOT&PF 
proposes 7-day work weeks, NMFS calculates the total number of work 
weeks to occur within 131 construction days as 19 weeks rather than 
ADOT&PF's proposed 22 weeks (1 Northern elephant seal x 19 work weeks = 
19 takes by Level B harassment).
    For most project activities, the proposed shutdown zone would 
exceed the Level A harassment zone for Northern elephant seal. However, 
the Level A harassment zone may extend beyond the proposed shutdown 
zone for this species on 37 days (when DTH systems may be employed to 
install 24-inch piles or 30-inch piles may be installed with an impact 
pile driver (200 strikes). While unlikely given the already low 
occurrence of Northern elephant seals, on those days, a Northern 
elephant seal could occur in the Level A harassment zone and remain in 
the zone for a long enough duration to incur PTS, and NMFS 
conservatively proposes to authorize five takes by Level A harassment. 
As such, NMFS proposes to authorize 14 takes by Level B harassment (1 
Northern elephant seal x 19 work weeks-5 takes by Level A harassment = 
14 takes by Level B harassment).
Harbor Seal
    During marine mammal monitoring associated with ADOT&PF's previous 
Tongass Narrows construction activities, 550 harbor seals were observed 
with an average of 1.2 harbor seals per day and a maximum group size of 
5. The COK pinnacle rock blasting project recorded a total of 21 harbor 
seal sightings of 24 individuals over 76.2 hours of pre- and

[[Page 46767]]

post-blast monitoring (Sitkiewicz 2020). Additionally, information from 
PSOs associated with on-going construction indicates that a small 
number of harbor seals are regularly sighted at about 820 feet (250 
meters) from the project location (Wyatt, personal communication). 
Additionally, there are two key harbor seal haulouts about 7.1 miles 
(11.5 kilometers) from the project area on a mid-channel island to the 
southeast of the project site. Each haulout was monitored in 2022 with 
10 harbor seals observed at one haulout and 50 harbor seals observed at 
the other (Richland personal communication).
    ADOT&PF estimates, and NMFS concurs, that up to 2 groups of 3 
harbor seals could enter the Level B harassment zone per day (2 groups 
x 3 harbor seals x 131 days = 786). Further, NMFS also estimates that 
half the harbor seals occurring at the haulout sites within the project 
area could enter the Level B harassment zone on days when the 
ensonified area (during 30'' vibratory pile driving) reaches these 
haulout sites (30 harbor seals x 13 days = 390).
    ADOT&PF also estimates that 1 harbor seal could be taken by Level A 
harassment on each day of in-water work (1 harbor seal x 131 days =131 
takes by Level A harassment). For most project activities, the shutdown 
zone exceeds the Level A harassment zone. However, when an impact pile 
driver (200 strikes) is used to install 30-inch piles, the Level A 
harassment zone exceeds the associated shutdown zone. This could occur 
on 13 days. NMFS anticipates that three harbor seals could be taken by 
Level A harassment on each day that the Level A harassment isopleth for 
this species extends beyond the shutdown zone. Therefore, NMFS proposes 
to authorize 39 takes by Level A harassment (3 harbor seal x 13 days = 
39 takes by Level A harassment) and 1,137 takes by Level B harassment 
(786 takes by Level B harassment + 390 takes by Level B harassment-39 
takes by Level A harassment = 1,137 takes by Level B harassment).

           Table 9--Proposed Take by Stock and Harassment Type and as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
                                                                     Proposed authorized take
                                                                    --------------------------  Proposed take as
                Species                             Stock              Level B      Level A     a percentage of
                                                                      harassment   harassment   stock abundance
----------------------------------------------------------------------------------------------------------------
Minke whale............................  Alaska....................            4            0  .................
Fin whale..............................  Northeast Pacific.........            2            0                0.1
Humpback whale.........................  Central North Pacific.....          131            0                1.3
Gray whale.............................  Eastern North Pacific.....           10            0               0.04
Pacific white-sided dolphin............  North Pacific.............           60            0                0.2
Killer whale...........................  Eastern North Pacific                64            0                3.3
                                          Alaska Resident.
                                         Eastern North Pacific                                              21.2
                                          Northern Resident.
                                         West Coast Transient......                                         16.3
Harbor porpoise........................  Southeast Alaska..........           60           15                5.8
Dall's porpoise........................  Alaska....................           90           10                0.8
Steller sea lion.......................  Eastern U.S...............          645           10                1.5
Northern Elephant seal.................  California Breeding.......           14            5               <0.1
Harbor seal............................  Clarence Strait...........        1,137           39                4.3
----------------------------------------------------------------------------------------------------------------

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses. NMFS regulations require applicants for incidental 
take authorizations to include information about the availability and 
feasibility (economic and technological) of equipment, methods, and 
manner of conducting the activity or other means of effecting the least 
practicable adverse impact upon the affected species or stocks, and 
their habitat (50 CFR 216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
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.
    ADOT&PF must ensure that construction supervisors and crews, the 
monitoring team and relevant ADOT&PF staff are trained prior to the 
start of all pile driving and DTH activity, so that responsibilities, 
communication procedures, monitoring protocols, and operational 
procedures are clearly understood. New personnel joining during the 
project must be trained prior to commencing work.

Protected Species Observers

    ADOT&PF must employ PSOs and establish monitoring locations as 
described in the NMFS-approved Marine Mammal Monitoring Plan and 
Section 5 of the IHA. ADOT&PF must monitor the project area to the 
maximum extent possible based on the required number of PSOs, required 
monitoring locations, and environmental conditions. For all vibratory 
pile driving and removal and DTH, ADOT&PF must employ at least three 
PSOs. For all impact pile driving, ADOT&PF must employ at least two 
PSOs. The placement of the PSOs during all pile driving and removal and 
DTH activities will ensure that the entire shutdown zone is visible.

Pre- and Post-Activity Monitoring

    Monitoring must take place from 30 minutes prior to initiation of 
pile driving or DTH activity (i.e., pre-

[[Page 46768]]

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 10 are clear of 
marine mammals. Pile driving may commence following 30 minutes of 
observation when the determination is made that the shutdown zones are 
clear of marine mammals. Further, while not a requirement in the IHA, 
the 2019 Biological Opinion requires that if a work stoppage occurs and 
PSOs do not monitor the boundaries of the Level B harassment zone 
continuously during the work stoppage, the entire Level B harassment 
zone must be surveyed again for the presence of ESA-listed species 
before work may resume. Additionally, the 2019 Biological Opinion 
requires that in-water activities take place only between civil dawn 
and civil dusk when PSOs can effectively monitor for the presence of 
marine mammals and when the entire shutdown zone and adjacent waters 
are visible (e.g., monitoring effectiveness is not reduced due to rain, 
fog, snow, etc.). The 2019 Biological Opinion allows for pile driving 
to continue for up to 30 minutes after sunset during evening civil 
twilight, as necessary to secure a pile for safety prior to 
demobilization for the evening. PSO(s) will continue to observe 
shutdown and monitoring zones during this time. The length of the post-
activity monitoring period may be reduced if darkness precludes 
visibility of the shutdown and monitoring zones. As noted in the 
Endangered Species Act section, the Alaska Region has reinitiated 
Section 7 consultation, and these measures from the 2019 Biological 
Opinion are subject to change.

Soft Start

    Soft-start procedures provide additional protection to marine 
mammals by providing warning and/or giving marine mammals a chance to 
leave the area prior to the hammer operating at full capacity. ADOT&PF 
must use soft start techniques when impact pile driving. Soft start 
requires contractors to provide an initial set of three strikes at 
reduced energy, followed by a 30-second waiting period, then two 
subsequent reduced-energy strike sets. A soft start must be implemented 
at the start of each day's impact pile driving and at any time 
following cessation of impact pile driving for a period of 30 minutes 
or longer.

Shutdown Zones

    For all pile driving/removal and DTH activities, ADOT&PF will 
establish shutdown zones (Table 10). The purpose of a shutdown zone is 
generally to define an area within which shutdown of activity will 
occur upon sighting of a marine mammal (or in anticipation of an animal 
entering the defined area). Shutdown zones vary based on the activity 
type and duration and marine mammal hearing group (Table 10). In most 
cases, shutdown zones are based on the estimated Level A harassment 
isopleth distances for each hearing group. However, in cases where 
ADOT&PF asserted that it would be impracticable to shut down at the 
Level A harassment isopleth due to excessive work stoppages, a smaller 
shutdown zone is proposed (e.g., for high-frequency cetaceans and 
phocids during DTH rock socketing of 24-inch piles). Note that some of 
the proposed shutdown zones differ from those proposed by the ADOT&PF 
in their application (see Table 6-5 of ADOT&PF's application) due to 
our incorporation of sound source levels and DTH TL coefficients from 
ADOT&PF's SSV report.
    ADOT&PF anticipates that the maximum amount of activity within a 
given day may vary significantly (Table 7), with large differences in 
maximum zones sizes possible (Table 8). Given this uncertainty and 
concerns related to ESA-listed humpback whales and fin whales, and 
practicability concerns with shutting down, ADOT&PF proposes a tiered 
system to identify and monitor the appropriate Level A harassment zones 
and shutdown zones for large frequency cetaceans and phocids. This 
tiered system is based on the maximum expected number of piles to be 
installed (impact or vibratory pile driving) or the maximum expected 
DTH duration in a given day. At the start of each work day, ADOT&PF 
will determine the maximum scenario possible for that day (according to 
the defined duration intervals in Tables 8 and 10), which will 
determine the appropriate Level A harassment isopleth and associated 
shutdown zone for that day. This Level A harassment zone (Table 8) and 
associated shutdown zone (Table 10) must be implemented for the entire 
work day.
    The placement of PSOs during all pile installation and removal, and 
DTH activities (described in detail in the Proposed Monitoring and 
Reporting section) will ensure that the entire shutdown zones are 
visible during pile installation. If a marine mammal is observed 
entering or within the shutdown zones indicated in Table 10, pile 
driving must be delayed or halted. If pile driving is delayed or halted 
due to the presence of a marine mammal, the activity may not commence 
or resume until either the animal has voluntarily exited and been 
visually confirmed beyond the shutdown zone (Table 10) or 15 minutes 
(non-ESA-listed species) or 30 minutes (humpback whales and fin whales) 
have passed without re-detection of the animal. Further, pile driving 
activity must be halted upon observation of either a species for which 
incidental take is not authorized or a species for which incidental 
take has been authorized but the authorized number of takes has been 
met, entering or within the harassment zone.
    ADOT&PF must also avoid direct physical interaction with marine 
mammals during construction activity. If a marine mammal comes within 
10 m of such activity, operations must cease and vessels must reduce 
speed to the minimum level required to maintain steerage and safe 
working conditions.

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

[[Page 46769]]

 
Impact permanent............................  30................................               1             550              30             300             190              30           2,154
                                                                                               2                                                             300
                                                                                               3             720
                                              24 or 14..........................               1             140              10             300              80              20           1,000
                                                                                               2             290                                             160
                                                                                               3
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Impact, temporary...........................  24 or 14..........................             1-3             120              10             140              60              10           1,000
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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

Proposed Monitoring and Reporting

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

Visual Monitoring

    Monitoring must be conducted by qualified, NMFS-approved PSOs, who 
will be present during all pile installation and removal activities, 
including vibratory, impact, and DTH methods, in according with the 
following:
     PSOs must be independent (i.e., not construction 
personnel) and have no other assigned tasks during monitoring periods;
     At least one PSO must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
IHA;
     Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field), or training 
for prior experience performing the duties of a PSO during construction 
activity pursuant to a NMFS-issued IHA;
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator must be designated. The lead 
observer must have prior experience performing the duties of a PSO 
during construction activity pursuant to a NMFS-issued incidental take 
authorization; and
     PSOs must be approved by NMFS prior to beginning any 
activity subject to this IHA.
    PSOs should have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number of species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times, and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    ADOT&PF must employ two PSOs during all impact pile driving. 
ADOT&PF must employ three PSOs during all vibratory pile driving and 
DTH. A minimum of one PSO (the lead PSO) must be assigned to the active 
pile driving or DTH location to monitor the shutdown zones and as much 
of the harassment zones as possible. The observation points of the 
additional PSOs may vary depending on the construction activity and 
location of the piles. During impact pile driving, the second PSO would 
select the best location to observe as much of the Level A harassment 
and Level B harassment zones as possible. To select the best 
observation locations during vibratory installation and removal and DTH 
activities, prior to start of construction, the lead PSO will stand at 
the construction site to monitor the shutdown zones while two or more 
PSOs travel in opposite directions from the project site along Tongass 
Narrows until they have reached the edge of the

[[Page 46770]]

Level B harassment zone, where they will identify suitable observation 
points from which to observe. If visibility deteriorates so that the 
entire width of Tongass Narrows at the harassment zone boundary is not 
visible, additional PSOs may be positioned so that the entire width is 
visible, or work will be halted until the entire width is visible to 
ensure that any humpback whales or fin whales entering or within the 
harassment zone are detected by PSOs.
    PSOs must record all observations of marine mammals, regardless of 
distance from the pile being driven. PSOs shall document any behavioral 
reactions in concert with distance from piles being driven or removed.

Reporting

    A draft marine mammal monitoring report would be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance of any 
future IHAs for projects at the same location, whichever comes first. 
The report would include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact, vibratory or DTH), the total 
equipment duration for vibratory installation/removal or DTH for each 
pile or hole and total number of strikes for each pile (impact 
driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: Name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting; Time of sighting; Identification of the 
animal(s) (e.g., genus/species, lowest possible taxonomic level, or 
unidentified), PSO confidence in identification, and the composition of 
the group if there is a mix of species; Distance and bearing of each 
marine mammal observed relative to the pile being driven for each 
sighting (if pile driving was occurring at time of sighting); Estimated 
number of animals (min/max/best estimate); Estimated number of animals 
by cohort (adults, juveniles, neonates, group composition, sex class, 
etc.); Animal's closest point of approach and estimated time spent 
within the harassment zone; Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);
     Number of marine mammals detected within the harassment 
zones, by species;
     Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    ADOT&PF must also submit all PSO datasheets and/or raw sighting 
data with the draft report, as specified in condition 6(b) of this IHA.
    If no comments are received from NMFS within 30 days, the draft 
report will constitute the final report. If comments are received, a 
final report addressing NMFS comments must be submitted within 30 days 
after receipt of comments.

Reporting Injured or Dead Marine Mammals

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

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, the majority of our analysis applies to all 
the species listed in Table 2, given that many of the anticipated 
effects of this project on different marine mammal stocks are expected 
to be relatively similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, NMFS has identified species-specific factors to inform the 
analysis.
    Pile driving and DTH activities associated with the project, as 
outlined previously, have the potential to disturb or displace marine 
mammals.

[[Page 46771]]

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

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of the affected species or stocks are impacted by the activity, 
including ESA-designated critical habitat;
     The project area represents a very small portion of the 
available foraging area for all potentially impacted marine mammal 
species and stocks and anticipated habitat impacts are minor; and
     Monitoring reports from similar work in Tongass Narrows 
have documented little to no effect on individuals of the same species 
impacted by the specified activities.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted previously, only take of small numbers of marine mammals 
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The instances of take NMFS proposes to authorize is below one-third 
of the estimated stock abundance for all stocks (see Table 9). The 
number of animals that we expect to authorize to be taken from these 
stocks would be considered small relative to the relevant stocks' 
abundances even if each estimated taking occurred to a new individual, 
which is an unlikely scenario. Some individuals may return multiple 
times in a day, but PSOs would count them as separate takes 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 8 
years old. The most recent estimate was 13,110 animals for just a 
portion of the stock's range. Therefore, the 100 takes of this stock 
proposed for authorization clearly represent small numbers of this 
stock.
    Likewise, the Southeast Alaska stock of harbor porpoise has no 
official NMFS abundance estimate as the most recent estimate is greater 
than 8 years old. The most recent estimate was 1,302 animals (Muto et 
al. 2021) and it is highly unlikely this number has drastically 
declined. Therefore, the 75 authorized takes of this stock proposed for 
authorization clearly represent small numbers of this stock.
    There is no current or historical estimate of the Alaska minke 
whale stock, but there are known to be over 1,000 minke whales in the 
Gulf of Alaska (Muto et al. 2018), so the 4 takes proposed for 
authorization is small relative to estimated survey abundance, even if 
each proposed take occurred to a new individual. Additionally, the 
range of the Alaska stock of minke whales is extensive, stretching from 
the Canadian Pacific coast to the Chukchi Sea, and ADOT&PF's proposed 
project area would impact a small portion of this range.
    The best available abundance estimate for fin whale is not 
considered representative of the entire stock as surveys were limited 
to a small portion of the stock's range, but there are known to be over 
2,500 fin whales in the northeast Pacific stock (Muto et al. 2021). As 
such, the 2 takes proposed for authorization is small relative to the 
estimated survey abundance, even if each proposed take occurred to a 
new individual.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    Harbor seals are the marine mammal species most regularly harvested 
for subsistence by households in Ketchikan and Saxman (a community a 
few miles south of Ketchikan, on the Tongass Narrows). Eighty harbor 
seals were harvested by Ketchikan residents in 2007, which ranked 
fourth among all communities in Alaska that year for harvest of harbor 
seals. Thirteen harbor seals were harvested by Saxman residents in 
2007. In 2008, two Steller sea lions were harvested by Ketchikan-based 
subsistence hunters, but this is the only record of sea lion harvest by 
residents of either Ketchikan or Saxman. In 2012, the community of 
Ketchikan had an estimated subsistence take of 22 harbor seals and 0 
Steller sea lion (Wolf et al. 2013). NMFS is not aware of more recent 
data. Hunting usually occurs in October and November (Alaska Department 
of Fish and Game (ADF&G) 2009), but there are also records of 
relatively high harvest in May (Wolfe et al. 2013). The Alaska 
Department of Fish and Game (ADF&G) has not recorded harvest of 
cetaceans from Ketchikan or Saxman (ADF&G 2023).
    All project activities would take place within the industrial area 
of Tongass Narrows immediately adjacent to Ketchikan where subsistence 
activities do not generally occur. Both harbor seals and the Steller 
sea lions may be temporarily displaced from the project area. The 
project would also not have an adverse impact on the availability of 
marine mammals for subsistence use at locations farther away where 
these construction activities are not expected to take place. Some 
minor, short-term harassment of the harbor seals could occur, but given 
the information above, we would not expect such harassment to have 
effects on subsistence hunting activities.
    Based on the description of the specified activity, the measures 
described to minimize adverse effects on the availability of marine 
mammals for subsistence purposes, and the proposed mitigation and 
monitoring measures, NMFS has preliminarily determined that there will 
not be an unmitigable adverse impact on subsistence uses from ADOT&PF's 
proposed activities.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal

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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).
    On February 6, 2019, NMFS AKRO completed consultation with NMFS OPR 
for the Tongass Narrows Project and issued a Biological Opinion. Formal 
consultation was later reinitiated due to changes to ADOT&PF's action 
that were not considered in the February 2019 opinion (PCTS# AKR-2018-
9806/ECO# AKRO-2018-01287). NMFS' AKRO issued a revised Biological 
Opinion to NMFS OPR on December 19, 2019 which concluded that the take 
NMFS proposed to authorize through IHAs would not jeopardize the 
continued existence of any endangered or threatened species or destroy 
or adversely modify any designated critical habitat. NMFS AKRO 
determined that issuance of the 2022 IHA to ADOT&PF for work in Tongass 
Narrows did not require reinitiation of the December 2019 Biological 
Opinion.
    NMFS OPR is proposing to authorize take of fin whale and Central 
North Pacific stock of humpback whales, of which a portion belong to 
the Mexico DPS of humpback whales, which are ESA-listed. The December 
19, 2019 Biological Opinion reinitiation clause (2) and (3), state that 
formal consultation should be reinitiated if ``new information reveals 
effects of the agency action that may affect ESA-listed species or 
critical habitat in a manner or to an extent not previously 
considered'' and ``the agency action is subsequently modified in a 
manner that causes an effect on the listed species or critical habitat 
not considered in this biological opinion.'' Given the additional take 
that NMFS OPR proposes to authorize, as described herein, NMFS has 
reinitiated consultation internally on the issuance of this proposed 
IHA under section 101(a)(5)(D) of the MMPA.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to ADOT&PF for conducting ferry berth construction in 
Tongass Narrows in Ketchikan, Alaska provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated. 
The IHA would be valid for 1 year from the date of issuance. A draft of 
the proposed IHA can be found at: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed 
construction activities. We also request comment on the potential 
renewal of this proposed IHA as described in the paragraph below. 
Please include with your comments any supporting data or literature 
citations to help inform decisions on the request for this IHA or a 
subsequent renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, 1 year renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical or nearly 
identical activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
    Upon review of the request for renewal, the status of the affected 
species or stocks, and any other pertinent information, NMFS determines 
that there are no more than minor changes in the activities, the 
mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: July 17, 2023.
Angela Somma,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2023-15441 Filed 7-19-23; 8:45 am]
BILLING CODE 3510-22-P