[Federal Register Volume 89, Number 8 (Thursday, January 11, 2024)]
[Notices]
[Pages 1884-1905]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-00390]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD574]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Sitka Seaplane Base Construction

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

ACTION: Notice; proposed incidental harassment authorizations; request 
for comments on proposed authorizations and possible renewals.

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SUMMARY: NMFS has received a request from the City and Borough of Sitka 
(CBS) for authorization to take marine mammals incidental to Sitka 
seaplane base construction activities over two years in Sitka, Alaska. 
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting 
comments on its proposal to issue two incidental harassment 
authorizations (IHA) to incidentally take marine mammals during the 
specified activities. NMFS is also requesting comments on possible one-
time, 1-year renewals for each IHA that could be issued under certain 
circumstances and if all requirements are met, as described in Request 
for Public Comments at the end of this notice. NMFS will consider 
public comments prior to making any final decision on the issuance of 
the requested MMPA authorizations and agency responses will be 
summarized in the final notice of our decision.

DATES: Comments and information must be received no later than February 
12, 2024.

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 
<a href="/cdn-cgi/l/email-protection#511805017f3930233d3032393423113f3e30307f363e27"><span class="__cf_email__" data-cfemail="6d24393d43050c1f010c0e05081f2d03020c0c430a021b">[email protected]</span></a>. Electronic copies of the application and 
supporting documents, as well as a list of the references cited in this 
document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems accessing these documents, 
please call the contact listed above.
    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 https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities without change. All 
personal identifying information (e.g., name, address) voluntarily 
submitted by the commenter may be publicly accessible. Do not submit 
confidential business information or otherwise sensitive or protected 
information.

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

SUPPLEMENTARY INFORMATION:

[[Page 1885]]

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 NAO 216-6A, which do not 
individually or cumulatively have the potential for significant impacts 
on the quality of the human environment and for which we have not 
identified any extraordinary circumstances that 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 September 1, 2023, NMFS received a request from CBS for two IHAs 
to take marine mammals incidental to the Sitka seaplane base 
construction project in Sitka, Alaska, over the course of two years. 
Following NMFS' review of the application and a revised version, CBS 
submitted a final version on November 15, 2023. The application was 
deemed adequate and complete on December 1, 2023. For both IHAs, CBS's 
request is for take of seven species of marine mammals by Level B 
harassment and, for a subset of three of these species, Level A 
harassment. Neither CBS nor NMFS expect serious injury or mortality to 
result from this activity and, therefore, IHAs are appropriate.

Description of Proposed Activity

Overview

    CBS proposes to replace the existing seaplane base in the Sitka 
Channel in Sitka, Alaska. The purpose of this project is to construct a 
new seaplane base, which would address existing capacity, safety, and 
condition deficiencies for critical seaplane operations, and for all 
seaplanes to transit the Sitka Chanel more safely. The proposed 
location of the new seaplane base in the Sitka Channel is located on 
the northern shore of Japonski Island in the Sitka Sound. Over the 
course of 2 years spanning July 2024-June 2025 and July 2025-June 2026, 
CBS would use a variety of methods, including vibratory and impact pile 
driving, and down-the-hole (DTH) drilling to install and remove piles. 
These methods of pile driving would introduce underwater sounds that 
may result in take, by Level A and Level B harassment, of marine 
mammals.

Dates and Duration

    CBS anticipates that the seaplane base construction project would 
occur over 2 years (phases). The in-water work window would last from 
July 2024 to June 2025 (Phase I) and July 2025 to June 2026 (Phase II). 
Pile driving and removal activities are anticipated to take 45 hours 
over 31 days in Phase I and 13 hours over 9 days in Phase II. All in-
water pile driving would be completed during daylight hours. The Phase 
I IHA would be valid from July 1, 2024 to June 30, 2025, and the Phase 
II IHA would be valid from July 1, 2025 to June 30, 2026.

Specific Geographic Region

    The CBS seaplane base is located on the northern shore of Japonski 
Island in the Sitka Channel. Sitka Channel separates Japonski Island 
from Sitka Harbor and downtown Sitka on the much larger Baranof Island. 
The Sitka Channel is located on the eastern shore of Sitka Sound, west 
of Crescent Bay and adjacent to Whiting Harbor. Sitka Channel is 
bookended by the Channel Rock Breakwaters to the north and James 
O'Connell Bridge to the south. Sitka Channel is approximately 150 feet 
(ft) (46 meters (m)) wide and about 22 ft (6.7 m) deep at its 
narrowest.

[[Page 1886]]

[GRAPHIC] [TIFF OMITTED] TN11JA24.000

Figure 1--Project Location

Detailed Description of the Specified Activity

    The purpose of the proposed project is to replace the existing 
seaplane base in Sitka that has come to the end of its useful life and 
has several shortcomings, including limited docking capacity. The 
existing facility is expensive to maintain, has wildlife conflicts with 
a nearby seafood processing plant, and requires pilots to navigate a 
busy channel with heavy ship traffic. The new seaplane base would 
improve safety of seaplane operations by reducing traffic and 
congestion in Sitka Channel. The proposed project would consist of 
several components including in-water and landside construction, 
completed over two phases. All components of landside construction 
would not cause harassment of marine mammals and are not discussed 
further.
    Phase I would involve the installation and removal of temporary 
piles, and the installation of permanent piles. During Phase I, 10 16-
inch (in, 0.4 m) and 16 24-in (0.6 m) permanent steel piles would be 
installed. The installation and removal of 12 temporary 16-in (0.4 m) 
steel pipe piles would be completed to support permanent pile 
installation. Vibratory hammers, impact hammers, and DTH drilling would 
be used for the installation and removal of the piles (table 1). The 
installation and removal of temporary piles would be conducted using 
impact and vibratory hammers. All permanent piles would be initially 
installed with a vibratory hammer. After vibratory driving, piles would 
be socketed into the bedrock with DTH drilling equipment. Finally, 
piles would be driven the final few inches of embedment with an impact 
hammer.
    Phase II similarly would involve the installation and removal of 
temporary piles, and the installation of permanent piles. During Phase 
II six 24-in (0.6 m) steel piles would be installed. The installation 
and removal of six temporary 16-in (0.4 m) steel pipe piles would be 
completed to support the permanent pile installation. As in Phase I, 
vibratory hammers, impact hammers, and DTH drilling would be used for 
the installation and removal of the piles (table 2). The installation 
and removal of temporary piles would be conducted using impact and 
vibratory hammers. All permanent piles would be initially installed 
with a vibratory hammer. After vibratory driving, piles would be 
socketed into the bedrock with DTH drilling equipment. Finally, piles 
would be driven the final few inches of embedment with an impact 
hammer.

                         Table 1--Phase 1 Project Pile Installation and Removal Summary
----------------------------------------------------------------------------------------------------------------
                                                   Temp install     Temp remove    Perm install    Perm Install
                Project component                     (16-in)         (16-in)         (16-in)         (24-in)
----------------------------------------------------------------------------------------------------------------
Total # of piles................................              12              12              10              16
----------------------------------------------------------------------------------------------------------------
                                             Vibratory Pile Driving
----------------------------------------------------------------------------------------------------------------
Max # of piles/day..............................               6               6               6               6
Time/pile (minutes).............................              10              10              10              10
Time/day (min)..................................              60              60              60              60

[[Page 1887]]

 
# of days.......................................               2               2             1.7             2.7
Total # of hours................................               2               2             1.7             2.7
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                                                  DTH Drilling
----------------------------------------------------------------------------------------------------------------
Max # of piles/day..............................  ..............  ..............               2               2
strikes/pile....................................  ..............  ..............          36,000          54,000
strikes/sec.....................................  ..............  ..............              10              10
time/pile.......................................  ..............  ..............              60              90
time/day (min)..................................  ..............  ..............             120             180
# of days.......................................  ..............  ..............               5               8
Total # of hours................................  ..............  ..............              10              24
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                                               Impact Pile Driving
----------------------------------------------------------------------------------------------------------------
Max # of piles/day..............................               4  ..............               4               4
strikes/pile....................................             175  ..............             175             175
time/pile (min).................................               5  ..............               5               5
time/day (min)..................................              20  ..............              20              20
# of days.......................................               3  ..............             2.5               4
Total # of hours................................               1  ..............             0.8             1.3
----------------------------------------------------------------------------------------------------------------


                         Table 2--Phase 2 Project Pile Installation and Removal Summary
----------------------------------------------------------------------------------------------------------------
                                                                   Temp install     Temp remove    Perm install
                        Project component                             (16-in)         (16-in)         (24-in)
----------------------------------------------------------------------------------------------------------------
Total # of piles................................................               6               6               6
----------------------------------------------------------------------------------------------------------------
                                             Vibratory Pile Driving
----------------------------------------------------------------------------------------------------------------
Max # of piles/day..............................................               6               6               6
Time/pile (minutes).............................................              10              10              10
Time/day (min)..................................................              60              60              60
# of days.......................................................               1               1               1
Total # of hours................................................               1               1               1
----------------------------------------------------------------------------------------------------------------
                                                  DTH Drilling
----------------------------------------------------------------------------------------------------------------
Max # of piles/day..............................................  ..............  ..............               2
strikes/pile....................................................  ..............  ..............          54,000
strikes/sec.....................................................  ..............  ..............              10
time/pile.......................................................  ..............  ..............              90
time/day (min)..................................................  ..............  ..............             180
# of days.......................................................  ..............  ..............               3
Total # of hours................................................  ..............  ..............               9
----------------------------------------------------------------------------------------------------------------
                                               Impact Pile Driving
----------------------------------------------------------------------------------------------------------------
Max # of piles/day..............................................               4  ..............               4
strikes/pile....................................................             175  ..............             175
time/pile (min).................................................               5  ..............               5
time/day (min)..................................................              20  ..............              20
# of days.......................................................             1.5  ..............             1.5
Total # of hours................................................             0.5  ..............             0.5
----------------------------------------------------------------------------------------------------------------

    Additionally, this project would include in-water work that is not 
expected to result in take of marine mammals. During Phase I and II, 
CBS proposed to discharge fill below the high tide line. The excavated 
materials from above the high tide line would be placed below the high 
tide line to develop the seaplane base uplands. The fill would be 
placed using an excavator and dozer and then compacted using a 
vibratory soil compactor. The total area of placement of fill below the 
high tide line in Phase I would be 1.6 acres (6,475 square meters 
(m\2\)) and in Phase II would be 1.3 acres (5,261 m\2\). While marine 
mammals may behaviorally respond in some small degree to the noise 
generated by the placement of fill operations, given the slow, 
predictable movements of the equipment, and absent any other contextual 
features that would cause enhanced concern, NMFS does not expect CBS's 
planned placement of fill to result in the take of marine mammals and 
it is not discussed further.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

[[Page 1888]]

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, instead of reprinting the information. Additional 
information regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 3 lists all species or stocks for which take is expected and 
proposed to be authorized for this activity and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS' 
SARs). While no serious injury or mortality is anticipated or proposed 
to be authorized here, PBR and annual serious injury and mortality from 
anthropogenic sources are included here as gross indicators of the 
status of the species or stocks and other threats.
    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' 2022 U.S. Alaska SAR. All values presented in table 3 are the 
most recent available at the time of publication and are available 
online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                              Table 3--Species Likely Impacted by the Specified Activities
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                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Humpback Whale..................  Megaptera novaeangliae.  Hawai[revaps]i.........  -,-,N               11,278 (0.56, 7,265,          127         27
                                                                                                             2020).
                                                               Mexico-North Pacific...  T,D,Y               N/A (N/A, N/A, 2006)..        UND        0.6
    Minke Whale.....................  Balaenoptera             Alaska.................  -,-,N               N/A (N/A, N/A, 2018)..  .........          0
                                       acutorostrata.
Family Eschrichtiidae:
    Gray Whale......................  Eschrichtius robustus..  Eastern North Pacific..  -,-,N               26,960 (0.05, 25,849,         801        131
                                                                                                             2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer whale....................  Orca orcinus...........  Northern Resident......  -,-,N               302 (N/A, 302, 2018)..        2.2        0.2
                                                               Alaska Resident........  -,-,N               1,920 (N/A, 1,920,             19        1.3
                                                                                                             2019).
                                                               Gulf of Alaska/Aleutian  -,-,N               587 (N/A, 587, 2012)..        5.9        0.8
                                                                Islands/Bering Sea
                                                                Transient.
                                                               West Coast Transient...  -,-,N               349 (N/A, 349, 2018)..        3.5        0.4
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Northern Southeast       -,-,N               1,619 (0.26, 1,250,            13        5.6
                                                                Alaska.                                      2019).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Steller sea lion................  Eumetopias jubatus.....  Western Stock..........  E,D,Y               52,932 (N/A, 52,932,          318        254
                                                                                                             2019).
                                                               Eastern Stock..........  -,-,N               43,201 (N/A, 43,201,        2,592        112
                                                                                                             2017).
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vituline           Sitka/Chatham..........  -,-,N               13,289 (N/A, 11,883,          356         77
                                       richardii.                                                            2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\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.

    As indicated above, all 7 species (with 12 managed stocks) in table 
3 temporally and spatially co-occur with the activity to the degree 
that take is reasonably likely to occur. All species that could 
potentially occur in the proposed action area are included in table 8 
of the IHA application. While northern fur seal, Pacific white-sided

[[Page 1889]]

dolphin, Dall's porpoise, North Pacific right whale, sperm whale, fin 
whale, and Cuvier's beaked whale have been documented in or near Sitka 
Sound and Sitka Channel, the temporal and/or spatial occurrence of 
these species is such that take is not expected to occur, and they are 
not discussed further beyond the explanation provided here. These 
species are all considered to be rare (no sightings in recent years) or 
very rare (no local knowledge of sightings within the project vicinity) 
within Sitka Sound or near the action area. The take of these species 
has not been requested nor is proposed to be authorized and these 
species are not considered further in this document. In addition to 
what is included in Sections 3 and 4 of the application, the SARs, and 
NMFS' website, further localized data and detail informing the baseline 
for select species (i.e., information regarding current Unusual 
Mortality Events (UME) and important habitat areas) is provided below.
    Additionally, the Northern Sea Otter may be found in Sitka Sound. 
However, the Northern Sea Otter are managed by the U.S. Fish and 
Wildlife Service and are not considered further in this document.

Gray Whale

    The migration pattern of gray whales appears to follow a route 
along the western coast of Southeast Alaska, traveling northward from 
British Columbia through Hecate Strait and Dixon Entrance, passing the 
west coast of Baranof Island from late March to May and then return 
south in October and November (Jones et al. 1984, Ford et al. 2013). 
The project area is inside Sitka Sound on the northern shore of 
Japonski Island, adjacent to Baranof Island.
    During 190 hours of observation from 1994 to 2002 from Sitka's 
Whale Park, three gray whales were observed (Straley et al., 2017). 
During recent marine mammal surveys conducted in the vicinity of the 
project action area, no gray whales were sighted, and these species are 
not known or expected to occur near or within Sitka Channel (Windward 
2017; Turnagain 2017; Straley et al., 2017; Turnagain 2018; SolsticeAK 
2019; SolsticeAK 2020; Halibut Point Marine Services 2021; SolsticeAK 
2022). However, Sitka Sound is within a gray whale migratory route 
Biologically Important Area (BIA) (March-May; November-January) and a 
feeding BIA (March-June) (Wild et al., 2023).
    Since January 1, 2019, elevated gray whale strandings have occurred 
along the west coast of North America from Mexico through Alaska. This 
event has been declared an UME, though a cause has not yet been 
determined. More information is available at https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events.

Humpback Whale

    Humpback whales are the most commonly observed baleen whale in 
Sitka Sound. They have been observed in Southeast Alaska in all months 
of the year (Baker et al. 1985, 1986), although they are most common in 
Sitka Sound's Eastern Channel in November, December, and January 
(Straley et al., 2017). In late fall and winter, herring sometimes 
overwinter in deep fjords in Silver Bay and Eastern Channel, and 
humpback whales aggregate in these areas to feed on them. In the summer 
when prey is dispersed throughout Sitka Sound, humpback whales also 
disperse throughout the Sound (Straley et al., 2017).
    Humpback whales have been frequently observed during construction 
projects in Sitka Sound, including the Biorka Island Dock Replacement 
Project (Turnagain Marine Construction, 2018) and the Sitka GPIP 
Multipurpose Dock Project (Turnagain Marine Construction, 2017). During 
190 hours of observation from 1994 to 2002 from Sitka's Whale Park, 440 
humpback whales were observed (Straley et al., 2017). During 21 days of 
monitoring during the construction of GPIP Dock between October 9 and 
November 9, 2017, 39 humpback whales were observed (Turnagain 2017). No 
humpback whales were observed within Sitka Channel during the eight 
days of monitoring in January 2017 during the construction of the Sitka 
Petro Dock (Windward 2017). Near Biorka Island, about 25 kilometers 
south of the project, humpback whales were sighted in June (22 whales), 
July (3 whales), and September (2 whales) 2018 (Turnagain 2018). No 
whales were sighted in August during the Biorka Island monitoring 
effort. Humpback whales were not observed during recent monitoring 
conducted for short periods over 8 days in September 2018 within a 400-
meter radius surrounding the O'Connell Bridge Lightering Float 
(SolsticeAK 2019). During 39 days of monitoring in January through 
March 2020 for the Crescent Harbor Float Rebuild Project, no humpbacks 
were observed. Humpback whales were not observed in the project area 
during 5 days of monitoring in March 2022 during the geotechnical 
survey for this project (SolsticeAK 2022).
    Given their widespread range and their opportunistic foraging 
strategies, humpback whales may be in Sitka Sound year-round but are 
more likely to occur in the summer months, although they are not as 
frequent in the action area.
    According to Wade et al. (2016), humpback whales in Southeast 
Alaska are most likely to be from the Hawaii DPS (distinct population 
segment, 98 percent probability), with a 2 percent probability of being 
from the threatened Mexico DPS. Sitka Sound is within seasonal humpback 
whale feeding BIAs from March-May and September-December (Wild et al., 
2023).

Steller Sea Lion

    Steller sea lions occur year-round in the project area. Most are 
expected to be from the Eastern DPS; however, it is likely that some 
Steller sea lions in the action area are from the endangered Western 
DPS (Jemison et al. 2013; NMFS 2013). Jemison et al. (2013) estimated 
an average annual breeding season movement of 917 Western DPS Steller 
sea lions to Southeast Alaska. Based on surveys and analysis conducted 
by Hastings et al. (2020), an estimated 2.2 percent of Steller sea 
lions in the vicinity of the project are Western DPS Steller sea lions.
    Critical habitat has been defined in Southeast Alaska at major 
haulouts and major rookeries (50 CFR 226.202), but the project action 
area does not overlap with Steller sea lion critical habitat. The 
Biorka Island haulout is the closest designated critical habitat and is 
approximately 25 kilometers southwest of the project area.
    Based on Straley et al. (2017) and other vessel-based surveys 
conducted from 1994 to 2016, Steller sea lion numbers are highest near 
the project area in January and February. January was the most abundant 
month with about 190 Steller sea lions spotted. February and November 
were next with about 170 and 120 Steller sea lions spotted, 
respectively. The fewest Steller sea lions were spotted in the month of 
May (1995-2002).
    Individual sea lions were seen on 19 of 21 days in Silver Bay and 
Easter Channel during monitoring for GPIP dock construction between 
October and November 2017 (Turnagain 2017). Near Biorka Island, sea 
lions were seen infrequently; sea lions were sighted in June (six 
animals), July (two animals), and no sea lions were seen in August 2018 
(Turnagain 2018). During 8 days of monitoring in January 2017 for the 
Petro Marine dock, about 1.6 kilometers (1 mile) southwest of the Sitka 
SPB, individual sea lions were seen on 3 days (Windward 2017). Steller 
sea lions were observed 5 of 8 days during monitoring

[[Page 1890]]

conducted for 15-minute periods in September 2018 for the O'Connell 
Bridge Lightering Float (SolsticeAK 2019). During in-water construction 
work for the O'Connell Bridge Lightering Float Pile Replacement Project 
between June 9 and June 12, 2019, 42 Steller sea lions were sighted 
(SolsticeAK 2019). During 39 days of marine mammal monitoring for the 
Crescent Harbor Float Replacement Project in January and February 2020, 
six sea lions were observed southwest of Sitka Channel (SolsticeAK 
2020). Steller sea lions were most often observed alone or in small 
groups of 2 or 3 during these monitoring efforts; however, a group of 
more than 100 was sighted on at least 1 occasion (Straley et al. 2017; 
Windward 2017; SolsticeAK 2019; SolsticeAK 2020). During the original 
construction of the Halibut Point Marine Services dock facility, no 
Steller sea lions were recorded within the 200-meter shutdown zone 
during pile driving operations; however, observers indicated observing 
individual sea lions outside the 200-meter zone four to five times per 
week (McGraw, 2019).
    During the summer months, sea lions are seen in the project area 
daily. Two to three individual sea lions feed on fish carcasses dumped 
adjacent to the project site from fishing charter operations in a 
nearby private marina. However, during the fall and winter, the charter 
fishing operations are not underway and the sea lions are not as active 
in the area (McGraw, pers. com., 2019).

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 4.

                  Table 4--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans           150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true    275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)     50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

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

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact marine mammals and their habitat. 
The Estimated Take of Marine Mammals section later in this document 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
section, to draw conclusions regarding the likely impacts of these 
activities on the reproductive success or survivorship of individuals 
and whether those impacts are reasonably expected to, or reasonably 
likely to, adversely affect the species or stock through effects on 
annual rates of recruitment or survival.

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. 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

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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 and vibratory pile driving and DTH drilling. 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 (American National 
Standards Institute (ANSI) 1986; National Institute for Occupational 
Safety and Health (NIOSH) 1998; ANSI 2005; NMFS 2018a). 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 raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH 
1998; NMFS 2018a). 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 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 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 non-impulsive sound source types simultaneously.
    The likely or possible impacts of CBS's proposed activity on marine 
mammals involve both non-acoustic and acoustic stressors. Potential 
non-acoustic stressors could result from the physical presence of 
equipment and personnel; however, any impacts to marine mammals are 
expected to be primarily acoustic in nature. Acoustic stressors include 
effects of heavy equipment operation during pile driving and drilling.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving or drilling is the primary means by which 
marine mammals may be harassed from the CBS'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). In general, exposure to 
pile driving or drilling 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 or drilling 
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 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. 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 an 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)--TTS is a temporary, reversible 
increase in the threshold of audibility at a specified frequency or 
portion of an individual's hearing range above a previously established 
reference level (NMFS 2018). Based on data from cetacean TTS 
measurements (see Southall et al., 2007), a TTS of 6 dB is considered 
the minimum threshold shift clearly larger than any day-to-day or 
session-to-session variation in a subject's normal hearing ability 
(Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in 
Finneran

[[Page 1892]]

(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 auditory 
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 a time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019) for summaries). 
For cetaceans, published data on the onset of TTS are limited to the 
captive bottlenose dolphin (Tursiops truncatus), beluga whale 
(Delphinapterus leucas), harbor porpoise, and Yangtze finless porpoise 
(Neophocoena asiaeorientalis), and for pinnipeds in water, measurements 
of TTS are limited to harbor seals, elephant seals (Mirounga 
angustirostris), and California sea lions (Zalophus californianus). 
These studies examine hearing thresholds measured in marine mammals 
before and after exposure to intense sounds. The difference between the 
pre-exposure and post-exposure thresholds can be used to determine the 
amount of threshold shift at various post-exposure times. The amount 
and onset of TTS depends on the exposure frequency. Sounds at low 
frequencies, well below the region of best sensitivity, are less 
hazardous than those at higher frequencies, near the region of best 
sensitivity (Finneran and Schlundt, 2013). At low frequencies, onset-
TTS exposure levels are higher compared to those in the region of best 
sensitivity (i.e., a low frequency noise would need to be louder to 
cause TTS onset when TTS exposure level is higher), as shown for harbor 
porpoises and harbor seals (Kastelein et al., 2019a, 2019b). In 
addition, TTS can accumulate across multiple exposures, but the 
resulting TTS will be less than the TTS from a single, continuous 
exposure with the same SEL (Finneran et al., 2010; Kastelein et al., 
2014; Kastelein et al., 2015a; Mooney et al., 2009). This means that 
TTS predictions based on the total, cumulative SEL will overestimate 
the amount of TTS from intermittent exposures such as sonars and 
impulsive sources. Nachtigall et al. (2018) describe the measurements 
of hearing sensitivity of multiple odontocete species (bottlenose 
dolphin, harbor porpoise, beluga, and false killer whale (Pseudorca 
crassidens)) when a relatively loud sound was preceded by a warning 
sound. These captive animals were shown to reduce hearing sensitivity 
when warned of an impending intense sound. Based on these experimental 
observations of captive animals, the authors suggest that wild animals 
may dampen their hearing during prolonged exposures or if conditioned 
to anticipate intense sounds. Another study showed that echolocating 
animals (including odontocetes) might have anatomical specializations 
that might allow for conditioned hearing reduction and filtering of 
low-frequency ambient noise, including increased stiffness and control 
of middle ear structures and placement of inner ear structures (Ketten 
et al., 2021). Data available on noise-induced hearing loss for 
mysticetes are currently lacking (NMFS, 2018).
    Behavioral Harassment--Exposure to noise from pile driving and 
removal 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).
    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). Behavioral reactions can vary not only among 
individuals but also within an individual, depending on previous 
experience with a sound source, context, and numerous other factors 
(Ellison et al., 2012), and can vary depending on characteristics 
associated with the sound source (e.g., whether it is moving or 
stationary, number of sources, distance from the source). In general, 
pinnipeds seem more tolerant of, or at least habituate more quickly to, 
potentially disturbing underwater sound than do cetaceans, and 
generally seem to be less responsive to exposure to industrial sound 
than most cetaceans. Please see Appendices B-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). 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

[[Page 1893]]

and success, and the life history stage of the animal.
    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; 
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 (National Research 
Council (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--Although pinnipeds are known to haul out 
regularly on man-made objects, we believe that incidents of take 
resulting solely from airborne sound are unlikely due to the sheltered 
proximity between the proposed project area and haulout sites (outside 
of Sitka Channel). There is a possibility that an animal could surface 
in-water, but with head out, within the area in which airborne sound 
exceeds relevant thresholds and thereby be exposed to levels of 
airborne sound that we associate with harassment, but any such 
occurrence would likely be accounted for in our estimation of 
incidental take from underwater sound. Therefore, authorization of 
incidental take resulting from airborne sound for pinnipeds is not 
warranted, and airborne sound is not discussed further here. Cetaceans 
are not expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA.
Marine Mammal Habitat Effects
    CBS's construction activities could have localized, temporary 
impacts on marine mammal habitat and their prey by increasing in-water 
sound pressure levels and slightly decreasing water quality. However, 
its proposed location is within the Sitka harbor and is located in an 
area that is currently used by numerous commercial fishing and personal 
vessels. Construction activities are of short duration and would likely 
have temporary impacts on marine mammal habitat through increases in 
underwater and airborne sound. 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 drilling, impact, and vibratory pile driving, 
elevated levels of underwater noise would ensonify the project area 
where both fish 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.
    Temporary and localized increase in turbidity near the seafloor 
would occur in the immediate area surrounding the area where piles are 
installed or removed. In general, turbidity associated with pile 
installation is localized to about a 25-ft (7.6 m) radius around the 
pile (Everitt et al., 1980). The sediments of the project site would 
settle out rapidly when disturbed. Cetaceans are not expected to be 
close enough to the pile driving areas to experience effects of 
turbidity, and any pinnipeds could avoid localized areas of turbidity. 
Therefore, we expect the impact from increased turbidity levels to be 
discountable to marine mammals and do not discuss it further.

[[Page 1894]]

In-Water Construction Effects on Potential Foraging Habitat

    The proposed activities would not result in permanent impacts to 
habitats used directly by marine mammals as the project would not 
expand outside of the Sitka Channel, and no increases in vessel traffic 
in the area are expected as a result of this project. The total 
seafloor area likely impacted by the project is relatively small 
compared to the available habitat in Southeast Alaska. Sitka Sound is 
included as a BIA for humpback whales and gray whales, however the 
action area is within the breakwaters where baleen whales are rare. 
Additionally, the area already has elevated noise levels because of 
busy vessel traffic transiting through the area, and critical habitat 
impacts would not be permanent nor would it result long-term effects to 
the local population. No known rookeries or major haulouts would be 
impacted. Additionally, the total seafloor area affected by pile 
installation and removal is a small area compared to the vast foraging 
area available to marine mammals in the area. At best, the impact area 
provides marginal foraging habitat for marine mammals and fishes. 
Furthermore, pile driving at the project site would not obstruct 
movements or migration of marine mammals.

Effects on Potential Prey

    Sound may affect marine mammals through impacts on the abundance, 
behavior, or distribution of prey species (e.g., crustaceans, 
cephalopods, fish, zooplankton, etc.). 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 which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving on fish, although 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., 
Wardle et al., 2001; Jorgenson and Gyselman, 2009).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The most likely impact to fish from pile driving activities at the 
project areas would be temporary behavioral avoidance of the area. The 
duration of fish avoidance of an area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated.
    Construction activities, in the form of increased turbidity, have 
the potential to adversely affect forage fish in the project area. 
Forage fish form a significant prey base for many marine mammal species 
that occur in the project area. Increased turbidity is expected to 
occur in the immediate vicinity (on the order of 10 ft (3 m) or less) 
of construction activities. However, suspended sediments and 
particulates are expected to dissipate quickly within a single tidal 
cycle. Given the limited area affected and high tidal dilution rates, 
any effects on forage fish are expected to be minor or negligible.
    Avoidance by potential prey (i.e., fish) of the immediate area due 
to the temporary loss of this foraging habitat is also possible. 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 summary, given the short daily duration of sound associated with 
individual pile driving events and the relatively small areas being 
affected, pile driving activities associated with the proposed action 
are not likely to have a permanent adverse effect on any fish habitat, 
or populations of fish species. Any behavioral avoidance by fish of the 
disturbed area would still leave significantly large areas of fish and 
marine mammal foraging habitat in the nearby vicinity. Thus, we 
conclude that impacts of the specified 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 the IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).

[[Page 1895]]

    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., vibratory or impact pile driving and DTH 
drilling) 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 
harbor porpoise, harbor seals and Steller sea lions. Harbor porpoise 
have larger predicted auditory injury zones and due to their small size 
they could enter the Level A harassment zone and remain undetected for 
sufficient duration to incur auditory injury. While Steller sea lion do 
not have large Level A harassment zones, they are frequently sighted in 
the project area and therefor have some potential for auditory injury. 
Additionally harbor seals have larger Level A harassment zones and are 
common in the action area, and therefore have potential for auditory 
injury. Auditory injury is unlikely to occur for all other species, 
based on the unlikelihood of the species in the action area and the 
smaller Level A harassment zones. 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., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by TTS as, in most cases, the likelihood of 
TTS occurs at distances from the source less than those at which 
behavioral harassment is likely. TTS of a sufficient degree can 
manifest as behavioral harassment, as reduced hearing sensitivity and 
the potential reduced opportunities to detect important signals 
(conspecific communication, predators, prey) may result in changes in 
behavior patterns that would not otherwise occur.
    CBS's proposed activity includes the use of continuous (vibratory 
hammer and DTH drilling) and impulsive (DTH drilling and impact pile 
driving) sources, and therefore the RMS SPL thresholds of 120 and 160 
dB re 1 [mu]Pa are applicable.
    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). CBS's 
proposed activity includes the use of impulsive (impact pile-driving 
and DTH drilling) and non-impulsive (vibratory hammer and DTH drilling) 
sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds *  (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.

[[Page 1896]]

 
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1 [mu]Pa\2\s. In this table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

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).
    In order to calculate distances to the Level A harassment and Level 
B harassment thresholds for the methods and piles being used in this 
project, NMFS used acoustic monitoring data from other locations to 
develop source levels for the various pile types, sizes and methods 
(table 6). This analysis uses practical spreading loss, a standard 
assumption regarding sound propagation for similar environments, to 
estimate transmission of sound through water. For this analysis, the 
transmission loss factor of 15 (4.5 dB per doubling of distance) is 
used. A weighting adjustment factor of 2.5 or 2, a standard default 
value for vibratory pile driving and removal or impact driving and DTH 
respectively, were used to calculate Level A harassment areas.
    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. With 
regards to DTH mono-hammers, NMFS recommends proxy levels for Level A 
harassment based on available data regarding DTH systems of similar 
sized piles and holes (Denes et al., 2019; Guan and Miner, 2020; Reyff 
and Heyvaert, 2019; Reyff, 2020; Heyvaert and Reyff, 2021) (table 1 and 
2 includes number of piles and duration for each phase; table 6 
includes peak pressure, sound pressure, and sound exposure levels for 
each pile type).

               Table 6--Estimates Underwater Proxy Source Level for Pile Installation and Removal
----------------------------------------------------------------------------------------------------------------
              Method and pile type                Sound source at 10 meters                 Source
----------------------------------------------------------------------------------------------------------------
                Vibratory Hammer                            dB rms
----------------------------------------------------------------------------------------------------------------
16 in..........................................                          161  NAVFAC 2015.
24 in..........................................                          161  NAVFAC 2015.
----------------------------------------------------------------------------------------------------------------


                   DTH Drill                      dB rms    dB SEL    dB peak
----------------------------------------------------------------------------------------------------------------
16 in..........................................       167       146       172  Heyvaert and Reyff 2021, Guan and
                                                                                Miner 2020.
24 in..........................................       167       159       184  Heyvaert and Reyff 2021.
----------------------------------------------------------------------------------------------------------------
                 Impact Hammer                    dB rms    dB SEL    dB peak
----------------------------------------------------------------------------------------------------------------
16 in..........................................       185       175       200  Caltrans 2020.
24 in..........................................       190       177       203  Caltrans 2015.
----------------------------------------------------------------------------------------------------------------

Level B Harassment Zones

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

TL = B * log<INF>10</INF> (R<INF>1</INF>/R<INF>2</INF>),

Where:

TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R<INF>1</INF> = the distance of the modeled SPL from the driven 
pile, and
R<INF>2</INF> = the distance from the driven pile of the initial 
measurement.

    The recommended TL coefficient for most nearshore environments is 
the practical spreading value of 15. This value results in an expected 
propagation environment that would lie between spherical and 
cylindrical spreading loss conditions, which is the most appropriate 
assumption for CBS's proposed underwater activities. The Level B 
harassment zones and approximate amount of area ensonified for the 
proposed underwater activities are shown in table 7.

Level A Harassment Zones

    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 installation or removal, the optional 
User Spreadsheet

[[Page 1897]]

tool predicts the distance at which, if a marine mammal remained at 
that distance for the duration of the activity, it would be expected to 
incur PTS. The isopleths generated by the User Spreadsheet used the 
same TL coefficient as the Level B harassment zone calculations (i.e., 
the practical spreading value of 15). Inputs used in the User 
Spreadsheet (e.g., number of piles per day, duration and/or strikes per 
pile) are presented in tables 1 and 2. The maximum RMS SPL, SEL, and 
resulting isopleths are reported in tables 6 and 7.

                  Table 7--Level A and Level B Harassment Isopleths for Pile Driving Activities
----------------------------------------------------------------------------------------------------------------
                                                          Level A isopleth (m)                         Level B
             Activity              -----------------------------------------------------------------   isopleth
                                         LF           MF           HF        Phocids      Otariids       (m)
----------------------------------------------------------------------------------------------------------------
                                       Vibratory Pile Removal/Installation
----------------------------------------------------------------------------------------------------------------
Phase I:
    16-in temp install............          6.8          0.6         10.1          4.2          0.3      5,411.7
    16-in temp removal............          6.8          0.6         10.1          4.2          0.3      5,411.7
    16-in perm install............          6.8          0.6         10.1          4.2          0.3      5,411.7
    24-in perm install............          6.8          0.6         10.1          4.2          0.3      5,411.7
Phase II:
    16-in temp install............          6.8          0.6         10.1          4.2          0.3      5,411.7
    16-in temp removal............          6.8          0.6         10.1          4.2          0.3      5,411.7
    24-in perm install............          6.8          0.6         10.1          4.2          0.3      5,411.7
----------------------------------------------------------------------------------------------------------------
                                              DTH Pile Installation
----------------------------------------------------------------------------------------------------------------
Phase I:
    16-in perm install............           59          2.1         70.3         31.6          2.3    \1\ 8,500
    24-in perm install............        568.9         20.2        677.6        304.4         22.2    \1\ 8,500
Phase II:
    24-in perm install............        568.9         20.2        677.6        304.4         22.2    \1\ 8,500
----------------------------------------------------------------------------------------------------------------
                                            Impact Pile Installation
----------------------------------------------------------------------------------------------------------------
Phase I:
    16-in temp install............          231          8.2          275          123            9        464.2
    16-in perm install............          231          8.2          275          123            9        464.2
    24-in perm install............          313         11.1          373          168         12.2        1,000
Phase II:
    16-in temp install............          231          8.2          275          123            9        464.2
    24-in perm install............          313         11.1          373          168         12.2        1,000
----------------------------------------------------------------------------------------------------------------
\1\ The calculated Level B harassment zone is 13,594 m. However, the farthest distance that sound will transmit
  from the source is 8,500 m before transmission is stopped by landmasses.

Marine Mammal Occurrence

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information which 
will inform the take calculations.
    Daily occurrence probability of each marine mammal species in the 
action area is based on consultation with previous monitoring reports, 
local researchers and marine professionals. Occurrence probability 
estimates are based on conservative density approximations for each 
species and factor in historic data of occurrence, seasonality, and 
group size in Sitka Sound and Sitka Channel. A summary of proposed 
occurrence is shown in table 9. To accurately describe species 
occurrence near the action area, marine mammals were described as 
either common (species sighted consistently during all monitoring 
efforts in the project vicinity, assume one to two groups per day), 
frequent (species sighted with some consistency during most monitoring 
efforts in the project vicinity, assume one group per week), or 
infrequent (species sighted occasionally during a few monitoring 
efforts in the project vicinity, assume one group per 2 weeks).

                    Table 8--Estimated Occurrence of Group Sightings of Marine Mammal Species
----------------------------------------------------------------------------------------------------------------
                                                                Average group
               Species                       Frequency              size              Expected occurrence
----------------------------------------------------------------------------------------------------------------
Humpback whale......................  Frequent...............             3.4  1 group/week.
Minke whale \1\.....................  Infrequent.............             3.5  1 group/2 weeks.
Gray whale..........................  Infrequent.............             3.5  1 group/2 weeks.
Killer whale........................  Frequent...............             6.6  1 group/week.
Harbor porpoise.....................  Infrequent.............             5.0  1 group/2 weeks.
Harbor seal \2\.....................  Common.................             2.1  1-2 groups/day.
Steller sea lion \2\................  Common.................             2.0  1-2 groups/day.
----------------------------------------------------------------------------------------------------------------
\1\ Minke whale considered rare in Sitka Channel, but to be conservative they are treated as infrequent for take
  estimation as there is a small likelihood they could be in the area during the activity.
\2\ Likelihood of one group/day in the Level A harassment zone and likelihood of two groups/day in the level B
  harassment zone.


[[Page 1898]]

Take Estimation

    Here we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and proposed for authorization.
    For the total underwater take estimate, the daily occurrence 
probability for a species was multiplied by the estimated group size 
and by the number of days of each type of pile driving activity. Group 
size is based on the best available published research for these 
species and their presence in the action area.

Estimated take = Group size x Groups per day x Days of pile driving 
activity

    Take by Level A harassment is requested for Steller sea lions and 
harbor seals. Although Steller sea lion Level A harassment zones are 
small, as previously discussed they are known to spend extended periods 
of time within the breakwaters in Sitka sound and in the project area. 
Harbor seals are also common in the project area and although their 
Level A harassment zones are farther from the project area, CBS has 
requested a maximum shutdown zone of 125 m for harbor seals and 
therefor there is likelihood for take by Level A harassment of harbor 
seals. Take by Level A harassment is also requested for harbor 
porpoise. We are proposing a maximum shutdown zone for high frequency 
species of 300 m and therefor there is likelihood for some take by 
Level A harassment. Even though they are not as common within the 
breakwaters, their Level A harassment zone extends beyond the 
breakwaters and they are elusive in nature. The take by Level A 
harassment for both pinniped species, are based on a lower daily 
occurrence rate based on the frequency of sightings within the smaller 
Level A harassment zone of the breakwaters (table 8).
    Additionally, for species that are large and/or infrequent (gray 
whale, minke whale, humpback whale, and harbor porpoise) in Sitka Sound 
and are unlikely to be within the breakwaters where the proposed action 
will take place, take by Level B harassment is only anticipated to 
occur incidental to vibratory and DTH methods, given the larger Level B 
harassment zones which will extend beyond the breakwaters. Anticipated 
take by Level A harassment for harbor seal and harbor porpoise would 
likely occur only incidental to impact pile driving and DTH drilling, 
and anticipated take of Steller sea lion by Level A harassment would 
likely occur only incidental to DTH drilling, due to the larger Level A 
harassment zones for these activities. See table 7.

                  Table 9--Proposed Take of Marine Mammals by Level A and Level B Harassment and Percent of Stock Proposed To Be Taken
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Phase 1                                Phase 2
                                                                           -----------------------------------------------------------------------------
                  Species                                Stock                                         Percent of                             Percent of
                                                                              Level A      Level B       stock       Level A      Level B       stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale \1\.........................  Hawai[revaps]i...............            0           11          0.1            0          * 4            0
                                             Mexico-North Pacific \2\.....            0            0            0            0            0            0
Gray Whale.................................  Eastern North Pacific........            0            6            0            0          * 4            0
Minke Whale................................  Alaska.......................            0            6           NA            0          * 4           NA
Killer whale...............................  West Coast Transients........            0            3          0.9            0            1          0.3
                                             Gulf, Aleutian, Bering                   0            6          0.9            0            2          0.3
                                              Transient.
                                             Northern Resident............            0            3          0.9            0            1          0.3
                                             Alaska Resident..............            0           18          0.9            0            6          0.3
Harbor porpoise............................  Northern Southeast Alaska....          * 5            8          0.9          * 5          * 5          0.7
Harbor seal................................  Sitka/Chatham Alaska.........           48          130          1.3           13           38          0.4
Steller sea lion...........................  Eastern US...................           16          121          0.3            6           35          0.1
                                             Western US...................            0            3            0            0           2*            0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Take estimates are weighted based on calculated percentages of population for each distinct stock, assuming animals present would follow same
  probability of presence in project area. Humpback whale probability by stock based on Southeast Alaska estimates from NMFS 2021 (98 percent Hawaii
  DPS; 2 percent Mexico DPS).
\2\ ESA listed Mexico humpback whales take calculation resulted in less than 0.5 takes, therefore no takes are anticipate or are proposed for
  authorization.
* Where proposed calculated take was less than the average group size, the take was rounded up to a group size as that is likely what would be
  encountered.

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses. NMFS regulations require applicants for incidental 
take authorizations to include information about the availability and 
feasibility (economic and technological) of equipment, methods, and 
manner of conducting the activity or other means of effecting the least 
practicable adverse impact upon the affected species or stocks, and 
their habitat (50 CFR 216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat, as 
well as subsistence uses. This considers the nature of the potential 
adverse impact being mitigated (likelihood, scope, range). It further 
considers the likelihood that the measure will be effective if 
implemented (probability of accomplishing the mitigating result if 
implemented as planned), the likelihood of effective implementation 
(probability implemented as planned), and;
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, and impact on 
operations.

Mitigation Measures

    For each IHA, CBS must follow mitigation measures as specified 
below:
    <bullet> Ensure that construction supervisors and crews, the 
monitoring team, and relevant CBS staff are trained prior to the start 
of all pile driving and DTH drilling 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;
    <bullet> Employ Protected Species Observers (PSOs) and establish

[[Page 1899]]

monitoring locations as described in the application and the IHA. The 
Holder must monitor the project area to the maximum extent possible 
based on the required number of PSOs, required monitoring locations, 
and environmental conditions. For all pile driving and removal at least 
one PSO must be used. The PSO will be stationed as close to the 
activity as possible;
    <bullet> The placement of the PSOs during all pile driving and 
removal and DTH drilling activities will ensure that the entire 
shutdown zone is visible during pile installation;
    <bullet> Monitoring must take place from 30 minutes prior to 
initiation of pile driving or DTH drilling activity (i.e., pre-
clearance monitoring) through 30 minutes post-completion of pile 
driving or DTH drilling activity;
    <bullet> 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 and DTH drilling may commence following 30 minutes of 
observation when the determination is made that the shutdown zones are 
clear of marine mammals;
    <bullet> CBS 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; and
    <bullet> If a marine mammal is observed entering or within the 
shutdown zones indicated in table 10, pile driving and DTH drilling 
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 11) or 15 minutes have passed 
without re-detection of the animal.
    As proposed by the applicant, in water activities will take place 
only between civil dawn and civil dusk when PSOs can effectively 
monitor for the presence of marine mammals; during conditions with a 
Beaufort sea state of 4 or less. Pile driving and DTH drilling may 
continue for up to 30 minutes after sunset during evening civil 
twilight, as necessary to secure a pile for safety prior to 
demobilization during this time. The length of the post-activity 
monitoring period may be reduced if darkness precludes visibility of 
the shutdown and monitoring zones.

Shutdown Zones

    CBS will establish shutdown zones for all pile driving and DTH 
drilling activities. The purpose of a shutdown zone is generally to 
define an area within which shutdown of the activity would occur upon 
sighting of a marine mammal (or in anticipation of an animal entering 
the defined area). Shutdown zones would be based upon the Level A 
harassment isopleth for each pile size/type and driving method where 
applicable, as shown in table 10.
    For in-water heavy machinery activities other than pile driving, if 
a marine mammal comes within 10 m, work will stop and vessels will 
reduce speed to the minimum level required to maintain steerage and 
safe working conditions. A 10 m shutdown zone serves to protect marine 
mammals from physical interactions with project vessels during pile 
driving and other construction activities, such as barge positioning or 
drilling. If an activity 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 indicated in table 10 or 15 minutes have passed without 
re-detection of the animal. Construction activities must be halted upon 
observation of 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.
    All marine mammals will be monitored in the Level B harassment 
zones and throughout the area as far as visual monitoring can take 
place. If a marine mammal enters the Level B harassment zone, 
construction activities including in-water work will continue and the 
animal's presence within the estimated harassment zone will be 
documented.
    CBS would also establish shutdown zones for all marine mammals for 
which take has not been authorized or for which incidental take has 
been authorized but the authorized number of takes has been met. These 
zones are equivalent to the Level B harassment zones for each activity. 
If a marine mammal species not covered under this IHA enters the 
shutdown zone, all in-water activities will cease until the animal 
leaves the zone or has not been observed for at least 15 minutes, and 
NMFS will be notified about species and precautions taken. Pile driving 
will proceed if the non-IHA species is observed to leave the Level B 
harassment zone or if 15 minutes have passed since the last 
observation.
    If shutdown and/or clearance procedures would result in an imminent 
safety concern, as determined by CBS or its designated officials, the 
in-water activity will be allowed to continue until the safety concern 
has been addressed, and the animal will be continuously monitored.

                                Table 10--Proposed Shutdown and Monitoring Zones
----------------------------------------------------------------------------------------------------------------
                                                          Level A isopleth (m)                         Level B
             Activity              -----------------------------------------------------------------   isopleth
                                         LF           MF         HF \2\    Phocids \1\    Otariids       (m)
----------------------------------------------------------------------------------------------------------------
                                       Vibratory Pile Removal/Installation
----------------------------------------------------------------------------------------------------------------
Phase I:
    16-in temp install............           10           10           20           10           10        5,415
    16-in temp removal............           10           10           20           10           10        5,415
    16-in perm install............           10           10           20           10           10        5,415
    24-in perm install............           10           10           20           10           10        5,415
Phase II:
    16-in temp install............           10           10           20           10           10        5,415
    16-in temp removal............           10           10           20           10           10        5,415
    24-in perm install............           10           10           20           10           10        5,415
----------------------------------------------------------------------------------------------------------------
                                              DTH Pile Installation
----------------------------------------------------------------------------------------------------------------
Phase I:
    16-in perm install............           60           10           75           35           10        8,500

[[Page 1900]]

 
    24-in perm install............          570           30          300          125           30        8,500
Phase II:
    24-in perm install............          570           30          300          125           30        8,500
----------------------------------------------------------------------------------------------------------------
                                            Impact Pile Installation
----------------------------------------------------------------------------------------------------------------
Phase I:
    16-in temp install............          235           10          275          125           10          465
    16-in perm install............          235           10          275          125           10          465
    24-in perm install............          315           20          300          125           20        1,000
Phase II:
    16-in temp install............          235           10          275          125           10          465
    24-in perm install............          315           20          300          125           20        1,000
----------------------------------------------------------------------------------------------------------------
\1\ Maximum shutdown for phocids is reduced to 125 m as they are a common species within the breakwaters of
  Sitka Sound.
\2\ Maximum shutdown for high frequency species is reduced to 300 m, given the difficulty observing harbor
  porpoise at greater distances.

Protected Species Observers

    The placement of PSOs during all construction activities (described 
in the Proposed Monitoring and Reporting section) would ensure that the 
entire shutdown zone is visible. Should environmental conditions 
deteriorate such that the entire shutdown zone would not be visible 
(e.g., fog, heavy rain), pile driving would be delayed until the PSO is 
confident marine mammals within the shutdown zone could be detected.
    PSOs would monitor the full shutdown zones and the remaining Level 
A harassment and the Level B harassment zones to the extent 
practicable. Monitoring zones provide utility for observing by 
establishing monitoring protocols for areas adjacent to the shutdown 
zones. Monitoring zones enable observers to be aware of and communicate 
the presence of marine mammals in the project areas outside the 
shutdown zones and thus prepare for a potential cessation of activity 
should the animal enter the shutdown zone.

Pre-Activity Monitoring

    Prior to the start of daily in-water construction activity, or 
whenever a break in pile driving or DTH drilling of 30 minutes or 
longer occurs, PSOs would observe the shutdown and monitoring zones for 
a period of 30 minutes. The shutdown zone would be considered cleared 
when a marine mammal has not been observed within the zone for that 30-
minute period. If a marine mammal is observed within the shutdown zones 
listed in table 10, pile driving activity would be delayed or halted. 
If work ceases for more than 30 minutes, the pre-activity monitoring of 
the shutdown zones would commence. A determination that the shutdown 
zone is clear must be made during a period of good visibility (i.e., 
the entire shutdown zone and surrounding waters must be visible to the 
naked eye).

Soft-Start Procedures

    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. For 
impact pile driving, contractors would be required to provide an 
initial set of three strikes from the hammer at reduced energy, 
followed by a 30-second waiting period, then two subsequent reduced-
energy strike sets. Soft-start would 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.
    Based on our evaluation of the applicant's proposed measures NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

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:
    <bullet> Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
    <bullet> 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);
    <bullet> Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
    <bullet> How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
    <bullet> Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
    <bullet> Mitigation and monitoring effectiveness.

Visual Monitoring

    Marine mammal monitoring must be conducted in accordance with the 
conditions in this section and the IHA.

[[Page 1901]]

Marine mammal monitoring during pile driving activities would be 
conducted by PSOs meeting NMFS' following requirements:
    <bullet> PSOs must be independent of the activity contractor (for 
example, employed by a subcontractor) and have no other assigned tasks 
during monitoring periods;
    <bullet> At least one PSO would have prior experience performing 
the duties of a PSO during construction activity pursuant to a NMFS-
issued incidental take authorization;
    <bullet> Other PSOs may substitute education (degree in biological 
science or related field) or training for experience; and
    <bullet> Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator would be designated. The lead 
observer would be required to have prior experience working as a marine 
mammal observer during construction.
    PSOs should have the following additional qualifications:
    [cir] Ability to conduct field observations and collect data 
according to assigned protocols;
    [cir] Experience or training in the field identification of marine 
mammals, including the identification of behaviors;
    [cir] Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
    [cir] Writing skills sufficient to prepare a report of observations 
including but not limited to the number and species of marine mammals 
observed; dates and times when in-water construction activities were 
conducted; dates, times and reason for implementation of mitigation (or 
why mitigation was not implemented when required); and marine mammal 
behavior; and
    [cir] 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.
    <bullet> CBS must employ up to five PSOs depending on the size of 
the monitoring and shutdown zones. A minimum of two PSOs (including the 
lead PSO) must be assigned to the active pile driving location to 
monitor the shutdown zones and as much of the Level B harassment zones 
as possible.
    <bullet> CBS must establish monitoring locations with the best 
views of monitoring zones as described in the IHA and Monitoring Plan 
posted on our website.
    <bullet> Up to four monitors will be used at a time depending on 
the size of the monitoring area. PSOs would be deployed in strategic 
locations around the area of potential effects at all times during in-
water pile driving and removal. PSOs will be positioned at locations 
that provide full views of the monitoring zones and the Level A 
harassment Shutdown Zones. All PSOs would have access to high-quality 
binoculars, range finders to monitor distances, and a compass to record 
bearing to animals as well as radios or cell phones for maintaining 
contact with work crews.
    <bullet> Up to four PSOs will be stationed at the following 
locations: the project site, Sandy Beach Day use site, O'Connell 
lightering float, and Whale Park.
    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after all in water construction activities. In addition, PSOs 
would record all incidents of marine mammal occurrence, regardless of 
distance from activity, and would document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving 
activities include the time to install or remove a single pile or 
series of piles, as long as the time elapsed between uses of the pile 
driving equipment is no more than 30 minutes.
    CBS shall conduct briefings between construction supervisors and 
crews, PSOs, CBS staff prior to the start of all pile driving 
activities and when new personnel join the work. These briefings would 
explain responsibilities, communication procedures, marine mammal 
monitoring protocol, and operational procedures.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities for each IHA, or 60 days prior to a requested date of 
issuance from any future IHAs for projects at the same location, 
whichever comes first. The report will include an overall description 
of work completed, a narrative regarding marine mammal sightings, and 
associated PSO data sheets. Specifically, the report must include:
    <bullet> Dates and times (begin and end) of all marine mammal 
monitoring;
    <bullet> 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 drilling) 
and the total equipment duration for vibratory removal for each pile or 
total number of strikes for each pile (impact driving);
    <bullet> PSO locations during marine mammal monitoring;
    <bullet> 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;
    <bullet> Upon observation of a marine mammal, the following 
information:
    <bullet> Name of PSO who sighted the animal(s) and PSO location and 
activity at the time of sighting;
    <bullet> Time of sighting;
    <bullet> Identification of the animal(s) (e.g., genus/species, 
lowest possible taxonomic level, or unidentifiable), PSO confidence in 
identification, and the composition of the group if there is a mix of 
species;
    <bullet> 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);
    <bullet> Estimated number of animals (min/max/best estimate);
    <bullet> Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition, sex class, etc.);
    <bullet> Animal's closest point of approach and estimated time 
spent within the harassment zone;
    <bullet> 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);
    <bullet> Number of marine mammals detected within the harassment 
zones and shutdown zones; by species; and
    <bullet> Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensured, and resulting changes in behavior of the 
animal(s), if any.
    If no comments are received from NMFS within 30 days, the draft 
reports will constitute the final reports. If comments are received, a 
final report addressing NMFS comments must be submitted within 30 days 
after receipt of comments.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the IHA-holder must 
immediately cease the specified activities and report the

[[Page 1902]]

incident to the Office of Protected Resources (OPR) 
(<a href="/cdn-cgi/l/email-protection#adfdff83e4f9fd83e0c2c3c4d9c2dfc4c3caffc8ddc2dfd9deedc3c2cccc83cac2db"><span class="__cf_email__" data-cfemail="f1a1a3dfb8a5a1dfbc9e9f98859e83989f96a394819e838582b19f9e9090df969e87">[email protected]</span></a>), NMFS and to the Alaska Regional 
Stranding Coordinator as soon as feasible. If the death or injury was 
clearly caused by the specified activity, CBS 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:
    <bullet> Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Condition of the animal(s) (including carcass condition if 
the animal is dead);
    <bullet> Observed behaviors of the animal(s), if alive;
    <bullet> If available, photographs or video footage of the 
animal(s); and
    <bullet> 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 discussion of our analysis applies to all 
species listed in table 3, given that the anticipated effects of this 
activity on these different marine mammal stocks are expected to be 
similar. There is little information about the nature or severity of 
the impacts, or the size, status, or structure of any of these species 
or stocks that would lead to a different analysis for this activity. In 
addition, because both the number and nature of the estimated takes 
anticipated to occur are identical in Phase I and II, the analysis 
below applies to both of the IHAs.
    Pile driving and DTH drilling activities associated with the 
project, as outlined previously, have the potential to disturb or 
displace marine mammals. Specifically, the specified activities may 
result in take, in the form of Level B harassment and, for some 
species, Level A harassment from underwater sounds generated by pile 
driving and DTH drilling. Potential takes could occur if individuals 
are present in the ensonified zone when these activities are underway.
    No serious injury or mortality would be expected, even in the 
absence of required mitigation measures, given the nature of the 
activities. Further, no take by Level A harassment is anticipated for 
killer whales, humpback whales, gray whales, or minke whales due to the 
application of planned mitigation measures, such as shutdown zones that 
encompass the Level A harassment zones for the species, the rarity of 
the species near the action area, and the small Level A harassment 
zones (for killer whales only). The potential for harassment would be 
minimized through the construction method and the implementation of the 
planned mitigation measures (see Proposed Mitigation section).
    Take by Level A harassment is proposed for three species (harbor 
porpoise, Steller sea lion, and harbor seal) as the Level A harassment 
isopleths exceed the size of the shutdown zones for specific 
construction scenarios, the Level A harassment zones are large, and/or 
the species is frequent near the action area. Therefore, there is the 
possibility that an animal could enter a Level A harassment zone and 
remain within that zone for a duration long enough to incur PTS. Level 
A harassment of these species is therefore proposed for authorization. 
Any take by Level A harassment is expected to arise from, at most, a 
small degree of PTS (i.e., minor degradation of hearing capabilities 
within regions of hearing that align most completely with the energy 
produced by impact pile driving such as the low-frequency region below 
2 kHz), not severe hearing impairment or impairment within the ranges 
of greatest hearing sensitivity. 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.
    Further, the amount of take proposed for authorization by Level A 
harassment is very low for the marine mammal stocks and species. If 
hearing impairment occurs, it is most likely that the affected animal 
would lose only a few decibels in its hearing sensitivity. Due to the 
small degree anticipated, any PTS potential incurred would not be 
expected to affect the reproductive success or survival of any 
individuals, much less result in adverse impacts on the species or 
stock.
    The Level A harassment zones identified in table 7 are based upon 
an animal exposed to pile driving or DTH drilling of several piles per 
day (six piles per day for vibratory removal and installation, four 
piles per day of impact driving, and two piles per day of DTH 
drilling). Given the short duration to impact drive or vibratory 
install or remove, or use DTH drilling, each pile and break between 
pile installations (to reset equipment and move piles into place), an 
animal would have to remain within the area estimated to be ensonified 
above the Level A harassment threshold for multiple hours. This is 
highly unlikely given marine mammal movement patterns in the area. If 
an animal was exposed to accumulated sound energy, the resulting PTS 
would likely be small (e.g., PTS onset) at lower frequencies where pile 
driving energy is concentrated, and unlikely to result in impacts to 
individual fitness, reproduction, or survival.
    Additionally, some subset of the individuals that are behaviorally 
harassed could also simultaneously incur some small degree of TTS for a 
short duration of time. However, since the hearing sensitivity of 
individuals that incur TTS is expected to recover completely within 
minutes to hours, it is unlikely that the brief hearing impairment 
would affect the individual's long-term ability to forage and 
communicate with conspecifics, and would therefore not likely impact 
reproduction or survival of any individual marine mammal, let alone

[[Page 1903]]

adversely affect rates of recruitment or survival of the species or 
stock.
    The nature of the pile driving project precludes the likelihood of 
serious injury or mortality. 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 and 
Level B harassment would be minimized through use of mitigation 
measures described herein. Further, the amount of take proposed to be 
authorized is extremely small when compared to stock abundance.
    Behavioral responses of marine mammals to pile driving, pile 
removals, and DTH drilling in Sitka Channel and the surrounding Sitka 
Sound 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 
observable such as changes in vocalization patterns. Given that pile 
driving, pile removal, and DTH drilling are temporary activities and 
effects would cease when equipment is not operating, any harassment 
occurring would be temporary. Additionally, many of the species present 
in the region would only be present temporarily based on seasonal 
patterns or during transit between other habitats. These species would 
be exposed to even smaller periods of noise-generating activity, 
further decreasing the impacts.
    Nearly all inland waters of southeast Alaska, including Sitka 
Sound, are included in the southeast Alaska humpback whale feeding BIA 
(Wild et al., 2023), though humpback whale distribution in southeast 
Alaska varies by season and waterway (Dahlheim et al., 2009). Humpback 
whales could be present within Sitka Sound year round, however the 
action area is within the breakwaters where humpback whales are not 
commonly found and therefore, the BIA is not expected to be affected. 
Therefore, the proposed project is not expected to have significant 
adverse effects on the foraging of humpback whales.
    Sitka Sound is also within a gray whale migratory corridor BIA 
(Wild et al., 2023). Construction is expected to occur while the BIA is 
active during the southbound migration (November to January) and 
northbound migration (March-May). The Sound is also a Gray whale 
feeding BIA. Construction is expected to overlap with the feeding BIA 
(March-June). However, as noted for humpback whales, project activities 
will only overlap seasonally in the gray whale migratory and feeding 
BIAs, and the overall 2 year project (Phase I and Phase II) is expected 
to occur over just 40 in-water workdays, further reducing the temporal 
overlap with the BIAs. Additionally, the area of the feeding BIA in 
which impacts of the planned project may occur is small relative to 
both the overall area of the BIA and the overall area of suitable gray 
whale habitat outside of this BIA. The area of Sitka Sound affected by 
this project is also small relative to the rest of the Sound, such that 
it allows animals within the migratory corridor to still utilize Sitka 
Sound without necessarily being disturbed by the construction. 
Specifically, all Level A harassment isopleths for gray whale are 
within the breakwaters where gray whales are not expected. Therefore, 
take of gray whales using the feeding and migratory BIAs is not 
expected to impact feeding or migratory behavior and, therefore, would 
not impact reproduction or survivorship.
    As noted previously, since January 1, 2019, elevated gray whale 
strandings have occurred along the west coast of North America from 
Mexico through Alaska. The event has been declared an UME, though a 
cause has not yet been determined. While 6 takes by Level B harassment 
in phase I and 4 takes by Level B harassment in phase II of gray whale 
are proposed to be authorized for each year this is an extremely small 
portion of the stock (<1 percent), and CBS will be required to 
implement a shutdown zone that includes the entire Level A harassment 
zone for low-frequency cetaceans such as gray whales.
    The same regions are also a part of the Western DPS Steller sea 
lion ESA critical habitat. While Steller sea lions are common in the 
project area, there are no essential physical and biological habitat 
features, such as haulouts or rookeries, within the proposed project 
area. The nearest haulout is approximately 25 km away from the proposed 
project area. Therefore, the proposed project is not expected to have 
significant adverse effects on the critical habitat of Western DPS 
Steller sea lions. No areas of specific biological importance (e.g., 
ESA critical habitat, other BIAs, or other areas) for any other species 
are known to co-occur with the project area.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat would have any effect on each stock's ability 
to recover. 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:
    <bullet> No serious injury or mortality is anticipated or 
authorized;
    <bullet> Level A harassment would be very small amounts and of low 
degree;
    <bullet> Level A harassment takes of only harbor porpoise, Steller 
sea lions and harbor seals;
    <bullet> For all species, the Sitka Sound and channel are a very 
small and peripheral part of their range;
    <bullet> Anticipated takes by Level B harassment are relatively low 
for all stocks. Level B harassment would be primarily in the form of 
behavioral disturbance, resulting in avoidance of the project areas 
around where impact or vibratory pile driving is occurring, with some 
low-level TTS that may limit the detection of acoustic cues for 
relatively brief amounts of time in relatively confined footprints of 
the activities;
    <bullet> Effects on species that serve as prey for marine mammals 
from the activities are expected to be short-term and, therefore, any 
associated impacts on marine mammal feeding are not expected to result 
in significant or long-term consequences for individuals, or to accrue 
to adverse impacts on their populations;
    <bullet> The ensonified areas are very small relative to the 
overall habitat ranges of all species and stocks, and would not 
adversely affect ESA-designated critical habitat for any species or any 
areas of known biological importance;
    <bullet> The lack of anticipated significant or long-term negative 
effects to marine mammal habitat; and
    <bullet> CBS would implement mitigation measures including soft-
starts and shutdown zones to minimize the numbers of marine mammals 
exposed to injurious levels of sound, and to ensure that take by Level 
A harassment is, at most, a small degree of PTS.
    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, specific to each of the 2 consecutive

[[Page 1904]]

years of proposed activity, would 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 amount of take NMFS proposes to authorize, for each of the 2 
consecutive years of proposed activity, is below one third of the 
estimated stock abundance for all species (in fact, take of individuals 
is less than 2 percent of the abundance of the affected stocks, see 
table 9). This is likely a conservative estimate because we assume all 
takes are of different individual animals, which is likely not the 
case. Some individuals may return multiple times in a day, but PSOs 
would count them as separate takes if they cannot be individually 
identified.
    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 10 takes by Level B 
harassment proposed over the 2 years of the project duration is small 
relative to estimated survey abundance, even if each take occurred to a 
new individual. Additionally, the range of the Alaska stock of minke 
whales is extensive, stretching from the Canadian Pacific coast to the 
Chukchi Sea, and CBS's project would only impact a small portion of 
this range.
    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, 
specific to each of the two consecutive years of proposed activity, 
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.
    Sitka Channel and other nearby areas are within the traditional 
territory of the Sheet'k[aacute] Bw[aacute]an. Alaska natives have 
traditionally harvested marine mammals in Sitka, however today a 
majority of the subsistence harvest is of species other than marine 
mammals. Alaska Department Fish and Game reported that in 2013, around 
11 percent of Sitka households used subsistence-caught marine mammals 
(ADF&G, 2023), however this is the most recent data available and there 
has not been a survey since.
    The proposed project is not likely to adversely impact the 
availability of any marine mammal species or stocks that are commonly 
used for subsistence purposes or impact subsistence harvest of marine 
mammals in the region because:
    <bullet> There is no recent recorded subsistence harvest of marine 
mammals in the area;
    <bullet> Construction activities are temporary and localized 
primarily within Sitka Channel;
    <bullet> Construction will not take place during the herring 
spawning season when subsistence species are more active;
    <bullet> Mitigation measures will be implemented to minimize 
disturbance of marine mammals in the action area; and,
    <bullet> The project will not result in significant changes to 
availability of subsistence resources.
    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, specific 
to each of the two consecutive years of proposed activity, there will 
not be an unmitigable adverse impact on subsistence uses from CBS's 
proposed activities.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS Office of Protected Resources (OPR) consults internally whenever 
we propose to authorize take for endangered or threatened species, in 
this case with the NMFS Alaska Regional Office (AKR).
    NMFS OPR has requested initiation of section 7 consultation with 
the NMFS AKR for the issuance of this IHA. NMFS will conclude the ESA 
consultation prior to reaching a determination regarding the proposed 
issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue two sequential IHAs, each lasting 1 year, to CBS for conducting 
Seaplane Base construction in Sitka, Alaska, starting in July 2024 for 
Phase I and July 2025 for Phase II, provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated. 
Drafts of the proposed IHAs can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHAs for the proposed 
construction project. We also request comment on the potential renewal 
of these proposed IHAs 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 these IHAs or subsequent 
renewal IHAs.
    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

[[Page 1905]]

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:
    <bullet> 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).
    <bullet> 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: January 5, 2024.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2024-00390 Filed 1-10-24; 8:45 am]
BILLING CODE 3510-22-P


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