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Notice2024-00390

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

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Published

January 11, 2024

Issuing agencies

Commerce DepartmentNational Oceanic and Atmospheric Administration

Abstract

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.

Full Text

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[Federal Register Volume 89, Number 8 (Thursday, January 11, 2024)]
[Notices]
[Pages 1884-1905]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[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&#160;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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. 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 <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a> 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
----------------------------------------------------------------------------------------------------------------
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
----------------------------------------------------------------------------------------------------------------
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; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.

Table 3--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\1\ abundance survey) \2\ SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order 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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports</a> 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 <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events">https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events</a>.

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

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(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

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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.

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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:
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.

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&#160;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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.

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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