[Federal Register Volume 88, Number 74 (Tuesday, April 18, 2023)]
[Notices]
[Pages 23627-23645]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-08186]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC395]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Skagway Ore Terminal 
Redevelopment Project in Skagway, Alaska

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

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

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SUMMARY: NMFS has received a request from the Municipality of Skagway 
(MOS) for authorization to take marine mammals incidental to the Ore 
Terminal redevelopment in Skagway, Alaska. Pursuant to the Marine 
Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue an incidental harassment authorization (IHA) to 
incidentally take marine mammals during the specified activities. NMFS 
is also requesting comments on a possible one-time, 1-year renewal that 
could be issued under certain circumstances and if all requirements are 
met, as described in the Request for Public Comments section at the end 
of this notice. NMFS will consider public comments prior to making any 
final decision on the issuance of the requested MMPA authorization and 
agency responses will be summarized in the final notice of our 
decision.

DATES: Comments and information must be received no later than May 18, 
2023.

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

FOR FURTHER INFORMATION CONTACT: Jenna Harlacher, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems 
accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

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

National Environmental Policy Act

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

[[Page 23628]]

Summary of Request

    On August 9, 2022, NMFS received a request from MOS for an IHA to 
take marine mammals incidental to Ore Terminal redevelopment in 
Skagway, Alaska. Following NMFS' review of the application and 
subsequent revised versions, MOS submitted a final application that was 
deemed adequate and complete on February 23, 2023. MOS's request is for 
take of 7 species (including 11 stocks) by Level B and Level A 
harassment. Neither MOS nor NMFS expect serious injury or mortality to 
result from this activity and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    MOS proposes to redevelop the Skagway Ore Terminal in Skagway, 
Alaska. The proposed project will cover construction from fall 2023 
through spring 2024 to avoid construction during cruise ship season. A 
maximum of 152 days of pile installation and removal activity will 
occur, with some days including both impact and vibratory pile driving. 
This project involves installation and removal of 36 temporary steel 
pile guides, removal of 692 piles, and installation of 244 permanent 
steel piles. Two different installation methods will be used including 
vibratory pile driving and impact pile driving. Sounds resulting from 
pile installation and removal may result in the incidental take of 
marine mammals by Level A and Level B harassment in the form of 
auditory injury or behavioral harassment.

Dates and Duration

    The proposed IHA would be effective from November 2023 through 
March 2024. The total expected work duration would be a max of 152 days 
with some days including both impact and vibratory pile driving (a 
total of 134 days of vibratory pile installation and 77 days of impact 
pile driving). This estimate is the maximum days of activity possible 
and is a conservative estimate that includes any potential delays. 
Because of the short construction season and limited winter daylight 
hours, construction would occur during both daylight hours and for a 
short time after sunset, with construction lighting.

Specific Geographic Region

    The proposed activity will occur in Skagway, Alaska, within the 
Skagway Ore Basin (Figure 1). Skagway is the northernmost city in 
Southeast Alaska. The MOS is at the southwestern end of the 2.5-mile (4 
kilometer) long Skagway River valley, which empties into Taiya inlet at 
the head of Lynn Canal. The Ore Terminal is a deep-water port that 
transitions sharply from a limited nearshore area into deep marine 
waters of Lynn Canal. The Ore Terminal basin area has nearly uniform 
depth of approximately 40 feet (12.2 meters) lower low water.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN18AP23.032

BILLING CODE 3510-22-C

[[Page 23629]]

Detailed Description of Specific Activity

    The proposed project will remove 269 steel and 423 creosote-treated 
timber piles from the existing Ore dock in Skagway Harbor. These piles 
will be removed using the vibratory hammer or directly pulled using a 
clamshell bucket. MOS proposes to install and remove 36 temporary steel 
piles using vibratory hammers; these piles will be removed by vibratory 
means by the end of construction. The temporary piles will act as 
supports or reaction frames to facilitate the installation of permanent 
piling. Steel permanent piles (248) will be installed to support the 
new dock structures, as part of the mooring dolphins, and as fender 
piles. Piles will be driven to the maximum depth feasible using a 
vibratory pile driver and partially driven and proofed using an impact 
pile driver to reach required depths. The piles would be installed 
using both methods over 152 days (Table 1).
    Additional actions occurring under the proposed action that are not 
anticipated to generate in-water noise resulting in marine mammal 
harassment include vessel movements to support construction and out of 
water dock components. NMFS does not expect that these ancillary 
activities will harm or harass marine mammals and no incidental takes 
are expected as a result of these activities. Therefore, these 
activities are not discussed further in this document.

                                Table 1--Pile Installation Methods and Durations
----------------------------------------------------------------------------------------------------------------
                                              Number of                                 Piles drive/  Estimated
            Pile size, method                   piles       Duration/strikes per pile       day          days
----------------------------------------------------------------------------------------------------------------
36-in steel pile **, Impact Installation.              78  1800 strikes...............            2           39
24-in steel pile, Impact Installation....             170  700 strikes................            5           38
30-in steel pile *, Vibratory                         439  45 min.....................            5           95
 Installation and Removal.
36-in steel pile **, Vibratory                         74  45 min.....................            5           15
 Installation.
14-in timber pile, Vibratory Removal.....             423  21 min.....................           18           24
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* Includes piles sizes: 10.75-in, 14-in, 16-in, 20-in, 24-in, 28-in, and 30-in.
** Includes pile sizes: 36-in, 42-in, and 48-in.

    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, referenced here, instead of reprinting the 
information. Additional information regarding population trends and 
threats may be found in NMFS' Stock Assessment Reports (SARs; 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS' 
website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
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 expected to occur, PBR 
and annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species or 
stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All stocks managed under the MMPA in this region 
are assessed in NMFS' 2021 Alaska Marine Mammal SARs. All values 
presented in Table 2 are the most recent available at the time of 
publication (including from the draft 2022 SARs) and are available 
online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                              Table 2--Species Likely Impacted by the Specified Activities
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                                                                                         ESA/MMPA status;    Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Humpback whale..................  Megaptera novaeanglinae  Central North Pacific    -,D,Y               10,103 (0.3, 7,890,            83         26
                                                                Stock.                                       2006).
    Minke whale.....................  Balaenoptera             Alaska.................  -,-,N               UNK...................         NA          0
                                       acutorostra.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer whale....................  Orca orcinus...........  Eastern North Pacific,   -,-,N               302 (N/A, 302, 2018)..        2.2        0.2
                                                                Norther Residents,
                                                                Southeast Alaska.

[[Page 23630]]

 
                                                               Eastern North Pacific    -,-,N               1,920 (N/A, 1,920,             19        1.3
                                                                Alaska Residents.                            2019).
                                                               West Coast Transients..  -,-,N               349 (N/A, 349, 2018)..        3.5        0.4
                                                               Gulf, Aleutian, Bering   -,-,N               587 (N/A, 587, 2020)..        5.9        0.8
                                                                Transients.
Family Phocoenidae (porpoises):
    Harbor Porpoise.................  Phocoena phocoena......  Southeast Alaska.......  -,-,N               1,057 (N/A,1,057,       .........         34
                                                                                                             2019).
    Dall's porpoise \4\.............  Phocoenoides dalli.....  Alaska.................  -,-,N               15,432 (0.28, 13, 110,        131         37
                                                                                                             2021).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
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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           Alaska--Lynn Canal/      -,-,N               13,388 (N/A, 11,867,          214         50
                                       richardii.               Stephens Passage.                            2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ Previous abundance estimates covering the entire stock's range are no longer considered reliable and the current estimates presented in the SARs and
  reported here only cover a portion of the stock's range. Therefore, the calculated Nmin and PBR is based on the 2015 survey of only a small portion of
  the stock's range. PBR is considered to be biased low since it is based on the whole stock whereas the estimate of mortality and serious injury is for
  the entire stock's range.

    On January 24, 2023, NMFS published the draft 2022 SARs (https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region). The Alaska and Pacific Ocean SARs 
include a proposed update to the humpback whale stock structure and the 
Alaska SAR includes a proposed update to the Southeast Alaska harbor 
porpoise stock structure. These new structures, if finalized, would 
modify the MMPA-designated humpback stocks to align more closely with 
the ESA-designated Distinct Population Segments (DPSs), and for harbor 
porpoise to align with genetics, trends in abundance, and discontinuous 
distribution that supports the delineation of two demographically 
independent populations. Please refer to the draft 2022 Alaska and 
Pacific Ocean SARs for additional information.
    NMFS Office of Protected Resources, Permits and Conservation 
Division has generally considered peer-reviewed data in draft SARs 
(relative to data provided in the most recent final SARs), when 
available, as the best available science, and has done so here for all 
species and stocks, with the exception of a new proposal to revise 
humpback whale and harbor porpoise stock structure. Given that the 
proposed changes to the stock structures involve application of NMFS's 
Guidance for Assessing Marine Mammals Stocks and could be revised 
following consideration of public comments, it is more appropriate to 
conduct our analysis in this proposed authorization based on the status 
quo stock structure identified in the most recent final SARs (2021; 
Carretta et al., 2022; Muto et al., 2022).
    As indicated above, all 7 species (with 11 managed stocks) in Table 
2 temporally and spatially co-occur with the activity to the degree 
that take is reasonably likely to occur, and for which we have proposed 
authorization. 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.
    A previous monitoring report from the White Pass & Yukon Route 
Railroad Dock Dolphin Installation project includes local marine mammal 
sighting data from Skagway. From their 57-day (March-May) protected 
species monitoring, no minke whale, harbor porpoise, or Dall's porpoise 
were sighted near the project area in Skagway. Twenty-six killer whales 
were sighted on 4 days, including 2 sightings in March and the rest in 
April. Killer whales were observed traveling, diving and swimming, and 
were observed greater than 300 m from the project site. Additionally, 
735 harbor seals were observed on 46 days of in-water activity, with 
sightings occurring in all months of the project. The majority of the 
harbor seal observations were near Yakutania Point, a harbor seal 
haulout site. Most of the sightings occurred at least 1,000 m from the 
project site, however harbor seals came as close as 150 m and as far as 
5,000 m. Harbor seals were observed travelling, swimming, playing, 
milling, looking, hauled out, sinking, and feeding (Owl Ridge Natural 
Resource Consultants, 2019).

Humpback Whale

    Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS established 14 Distinct Population 
Segments (DPS) with different listing statuses (81 FR 62259, September 
8, 2016) pursuant to the ESA.
    There are two MMPA stocks of humpback whales in the North Pacific 
in NMFS Alaska Marine Mammal SAR. Humpback whales from the Western 
North Pacific stock are not likely to be observed in Southeast Alaska 
and are

[[Page 23631]]

not expected in the project area. Individuals from the Central North 
Pacific stock of humpback whales are found in Southeast Alaska and have 
the potential to be in the project vicinity.
    Because DPSs do not overlap exactly with the existing MMPA stocks, 
there is the possibility that either the Hawaii DPS or the Mexico DPS 
could be in the project area (Muto et al., 2020). Although NMFS has 
determined that humpback whales in Southeast Alaska have a 98 percent 
probability of being from the Hawaii DPS (Wade et al., 2016), there is 
a 2 percent likelihood that a humpback whale from the Mexico DPS, which 
is threatened under the ESA, could be in the project area. No critical 
habitat has been designated for the humpback whale in the vicinity of 
the Project.
    Southeast Alaska primarily provides summer feeding grounds for 
humpback whales that typically arrive in Southeast Alaska between March 
and November, although they could be present in Southeast Alaska year-
round. Lynn Canal is within the North Pacific feeding and wintering 
area, and is a biologically import feeding ground for humpback whales 
(active June-August). However, these areas are outside of Taiya inlet 
and during months when the activity is not occurring.
    Local observers in Taiya Inlet have historically reported humpback 
whales; however, no scientific surveys have documented the species in 
the area (Dahlheim et al., 2009). During the White Pass & Yukon Route 
Railroad Dock Dolphin Installation project, humpback whales were 
sighted in Taiya Inlet twice in early May. These sightings occurred 3-4 
km from the project site and were observed travelling (Owl Ridge 
Natural Resource Consultants, 2019). Group sizes are largest in summer 
and fall, increasing over the course of the year and peaking in late 
August and September (Dalheim et al., 2009). The Central North Pacific 
stock is increasing at rates of up to approximately 7 percent per year 
(ADFG, 2008; Calambokidis et al., 2008).

Steller Sea Lion

    Steller sea lions were listed as threatened range-wide under the 
ESA on November 26, 1990 (55 FR 49204). Steller sea lions were 
subsequently partitioned into the western and eastern DPSs in 1997 (62 
FR 24345, May 5, 1997). The eastern DPS remained classified as 
threatened until it was delisted in November 2013. The western DPS 
(those individuals west of the 144[deg] W longitude or Cape Suckling, 
Alaska) was upgraded to endangered status following separation of the 
DPSs; it remains endangered today and considered a strategic stock 
under the MMPA. Both stocks of Steller sea lions are found in Southeast 
Alaska and have the potential to occur in the project area, however it 
is more likely they would be from the Eastern stock.
    Critical habitat for Steller sea lions was designated by NMFS in 
1993 based on the following essential physical and biological habitat 
features: terrestrial habitat (including rookeries and haulouts 
important for rest, reproduction, growth, social interactions) and 
aquatic habitat (including nearshore waters around rookeries and 
haulouts, free passage for migration, prey resources, and foraging 
habitats) (58 FR 45269).
    During the White Pass & Yukon Route Railroad Dock Dolphin 
Installation project, Steller sea lions were sighted on 27 separate 
days with 165 individuals. Majority of the sightings occurred during 
April and May, with only six individuals sighted in March. Although a 
few sightings were 500 meters from pile driving activities, most 
sightings were recorded over 1,000 meters away from the pile driving 
site. Sightings were of single individuals and rafts up to 25 
individuals. Steller sea lions were observed swimming, traveling, 
resting, porpoising, looking, sinking, and milling (Owl Ridge Natural 
Resource Consultants, 2019).
    Gran Point is the closest major haulout and designated critical 
habitat area, approximately 24 miles (38.6 kilometers) from the Project 
site and outside of Taiya Inlet (NOAA, 2022b). Additionally, there is a 
nearby Steller sea lion haulout at the southern tip of Taiya Inlet 
utilized by Steller sea lions during the Eulachon run. The Lutak Inlet 
Eulachon run between April and May correlates with higher sea lion 
numbers near the Project site, with the Taiya Point haulout 
(approximately 10 miles (16.1 kilometers) away) being a popular land 
site (NOAA, 2022b). However, the Eulachon run is outside of the project 
work window.

Marine Mammal Hearing

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

                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
               Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen        7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans (dolphins,     150 Hz to 160 kHz.
 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) (true    50 Hz to 86 kHz.
 seals).

[[Page 23632]]

 
Otariid pinnipeds (OW) (underwater) (sea    60 Hz to 39 kHz.
 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 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 section, and the Proposed Mitigation section, to draw 
conclusions regarding the likely impacts of these activities on the 
reproductive success or survivorship of individuals and whether those 
impacts are reasonably expected to, or reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.
    Acoustic effects on marine mammals during the specified activity 
can occur from impact and vibratory pile driving and removal. The 
effects of underwater noise from MOS's proposed activities have the 
potential to result in Level A or Level B harassment of marine mammals 
in the action area.

Description of Sound Source

    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 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 vibratory pile removal, and impact and vibratory pile driving. 
The sounds produced by these activities fall into one of two general 
sound types: impulsive and non-impulsive. Impulsive sounds (e.g., 
explosions, gunshots, sonic booms, impact pile driving) are typically 
transient, brief (less than 1 second), broadband, and consist of high 
peak sound pressure with rapid rise time and rapid decay (ANSI, 1986; 
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).
    Two types of hammers would be used on this project: impact and 
vibratory. 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).
    The likely or possible impacts of MOS's proposed activity on marine 
mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of 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.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving is the primary means by which marine 
mammals may be harassed from the MOS'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

[[Page 23633]]

general, exposure to pile driving 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 as 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 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 TS 
is customarily expressed in decibels (dB). A TS can be permanent or 
temporary. As described in NMFS (2018), there are numerous factors to 
consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
and vocalization frequency range of the exposed species relative to the 
signal's frequency spectrum (i.e., how 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 (2015), marine mammal studies have shown the amount of TTS 
increases with cumulative sound exposure level (SELcum) in an 
accelerating fashion: At low exposures with lower SELcum, the amount of 
TTS is typically small and the growth curves have shallow slopes. At 
exposures with higher SELcum, the growth curves become steeper and 
approach linear relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in Masking, 
below). For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that takes place during a time when the animal is traveling 
through the open ocean, where ambient noise is lower and there are not 
as many competing sounds present. Alternatively, a larger amount and 
longer duration of TTS sustained during 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, 2020a, 
2020b). 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) and Finneran (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

[[Page 23634]]

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; NRC, 2005).
    Disturbance may result in changing durations of surfacing and 
dives, number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); and, avoidance of areas where sound sources are located. 
Pinnipeds may increase their haul out time, possibly to avoid in-water 
disturbance (Thorson and Reyff, 2006). Behavioral responses to sound 
are highly variable and context-specific and any reactions depend on 
numerous intrinsic and extrinsic factors (e.g., species, state of 
maturity, experience, current activity, reproductive state, auditory 
sensitivity, time of day), as well as the interplay between factors 
(e.g., Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 
2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can 
vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al., 2012), and can vary depending 
on characteristics associated with the sound source (e.g., whether it 
is moving or stationary, number of sources, distance from the source). 
In general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem 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 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; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al., (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar projects in the area.
    Masking--Sound can disrupt behavior through masking, or interfering 
with, an animal's ability to detect, recognize, or discriminate between 
acoustic signals of interest (e.g., those used for intraspecific 
communication and social interactions, prey detection, predator 
avoidance, navigation) (Richardson et al., 1995). Masking occurs when 
the receipt of a sound is interfered with by another coincident sound 
at similar frequencies and at similar or higher intensity, and may 
occur whether the sound is natural (e.g., snapping shrimp, wind, waves, 
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar, 
seismic exploration) in origin. The ability of a

[[Page 23635]]

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 near Skagway and Taiya Inlet, we believe that incidents of 
take resulting solely from airborne sound are unlikely due to the 
sheltered proximity between the proposed project area and these haulout 
sites (Taiya point, Gran Point, Yakutania Point, and in Taiya Inlet). 
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

    The MOS'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, 
the proposed location is not heavily used by marine mammals and is in 
close proximity to a heavily trafficked industrial area. 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 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 meter) radius around 
the pile (Everitt et al., 1980). The sediments of the project site will 
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. 
Local strong currents are anticipated to disburse any additional 
suspended sediments produced by project activities at moderate to rapid 
rates depending on tidal stage. Therefore, we expect the impact from 
increased turbidity levels to be discountable to marine mammals and do 
not discuss it further.

In-Water Construction Effects on Potential Foraging Habitat

    The proposed activities would result in a minor loss of benthic 
habitat and potentially change underwater features for fish, but these 
changes are insignificant and limited to the area of redevelopment. The 
total seafloor area likely impacted by the project is relatively small 
compared to the available habitat in Southeast Alaska and does not 
include any Biologically Important Areas (BIA) or other habitat of 
known importance. The area is highly influenced by anthropogenic 
activities. 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.
    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.

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 that 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

[[Page 23636]]

shown no or slight reaction to impulse sounds (e.g., Pena et al., 2013; 
Wardle et al., 2001; Jorgenson and Gyselman, 2009; Popper et al., 
2015).
    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. 
Finally, exposure to turbid waters from construction activities is not 
expected to be different from the current exposure; fish and marine 
mammals in the Passage Canal are routinely exposed to substantial 
levels of suspended sediment from natural and anthropogenic sources.
    In summary, given the short-term and limited duration of sound 
associated with 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 be temporary and would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity. Additionally, all in-water work will occur during 
the winter, when marine resident fish species are only present in 
limited numbers. 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

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., vibratory and impact pile driving) 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. 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 permanent threshold shift (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.
    MOS's proposed activity includes the use of continuous (vibratory 
pile driving) and impulsive (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

[[Page 23637]]

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). MOS's proposed activity includes the use 
of impulsive (impact pile driving) and non-impulsive (vibratory pile 
driving) 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: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1 [micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI, 2013). However, American National Standards Institute (ANSI)
  defines peak sound pressure 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 and 
vibratory pile driving and removal).
    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 5).

    Table 5--Observed Source Levels for Pile Installation and Removal
------------------------------------------------------------------------
        Pile size, method             SPLs (dB)             Source
------------------------------------------------------------------------
36-in to 48-in steel pile**,                193 RMS  Caltrans 2020.
 Impact Installation.
24-in steel pile, Impact                    189 RMS  Caltrans 2020.
 Installation.
Up to 30-in steel pile*,                    159 RMS  Caltrans 2020.
 Vibratory Installation and
 Removal.
36-in steel pile**, Vibratory               170 RMS  Caltrans 2015.
 Installation.
14-in timber pile, Vibratory                158 RMS  Greenbusch 2018.
 Removal.
------------------------------------------------------------------------
Note: SPLs = single strike sound pressure level; RMS = root mean square.
* Includes piles sizes: 10.75-in, 14-in, 16-in, 20-in, 24-in, 28-in, and
  30-in.
** Includes pile sizes: 36-in, 42-in, and 48-in.

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 * log10 (R1/R2),

Where:

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

    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 MOS's proposed activities. The Level B harassment zones 
for the proposed activities are shown in Table 6.

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

[[Page 23638]]

removal, the optional User Spreadsheet tool predicts the distance at 
which, if a marine mammal remained at that distance for the duration of 
the activity, it would be expected to incur PTS. 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, source levels) are 
presented in Table 1 and Table 5. The resulting isopleths are reported 
in Table 6.

                                        Table 6--Level A and Level B Harassment Isopleths for Impact Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    Level A harassment zone (m)                               Level B
                        Activity                         --------------------------------------------------------------------------------   harassment
                                                            LF cetacean     MF cetacean     HF cetacean       Phocids        Otariids        zone (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-in to 48-in steel pile **, Impact Installation.......         2,345.7            83.4         2,794.1          1255.3            91.4         1,584.9
24-in steel pile, Impact Installation...................         1,245.8            44.3         1,483.9           666.7            48.5           857.7
Up to 30-in steel pile *, Vibratory Installation and                12.1             1.1            17.9             7.4             0.5           3,981
 Removal................................................
36-in steel pile **, Vibratory Installation.............            65.6             5.8              97            39.9             2.8          21,544
14-in timber pile, Vibratory Removal....................            14.7             1.3            21.7             8.9             0.6         3,414.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Includes piles sizes: 10.75-in, 14-in, 16-in, 20-in, 24-in, 28-in, and 30-in.
** Includes pile sizes: 36-in, 42-in, and 48-in.

Marine Mammal Occurrence

    In this section, we provide information about the occurrence of 
marine mammals, including density or other relevant information that 
will inform the take calculations.
    For marine mammal density information in the Skagway area we use 
data from the Pacific Navy Marine Species Density Database (U.S. Navy, 
2021) and sources specific to the Skagway area to estimate take for 
marine mammals. The Marine Species Density Database incorporates 
analyzed literature and research for marine mammal density estimates 
per season for the Gulf of Alaska and the Western Behm Canal. The 
Western Behm Canal is closer to the Project site and geographically 
more similar (an inlet compared to open ocean); therefore, density 
estimates for Western Behm Canal are used as proxies. Density estimates 
specific to Taiya Inlet or Lynn Canal are not available for any of the 
species addressed in this application, and therefore takes must be 
estimated based on the nearest available and most appropriate density 
estimates, plus site-specific knowledge and professional judgement. 
Table 7 density estimates are calculated based on the in-water work 
window (November-March) and based on winter density estimates of 
Western Behm Canal.

      Table 7--Density of Marine Mammal Species in the Project Area
------------------------------------------------------------------------
                                                           Density  (per
                         Species                              km \2\)
------------------------------------------------------------------------
Humpback whale..........................................          0.0081
Minke Whale.............................................          0.0017
Dall's Porpoise.........................................          0.1210
Harbor Porpoise.........................................          0.4547
Killer Whale............................................          0.0041
Harbor Seal.............................................           1.730
Steller Sea Lion........................................          0.0122
------------------------------------------------------------------------

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.
    Using the overall area of disturbance generated by pile removal and 
installation given calculated distances to attenuation below 
disturbance (Level B harassment) thresholds, incidental take for each 
activity is estimated by the following equation:

Incidental take estimate = species density * ensonified area* days of 
pile-related activity

    Due to little observational data available for marine mammals in 
Taiya Inlet and Lynn Canal in the winter, this equation is a reasonable 
extrapolation for take estimates, which relies on the likelihood that a 
species is present within the ensonified area on a day where the 
proposed activity is occurring. The estimation of take by Level A 
harassment is based on the likelihood that marine mammals would enter 
the Level A harassment zone without detection.

                                           Table 8--Proposed Authorized Amount of Taking and Percent of Stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Take by Level   Take by Level                    Percent of
                    Species                                     Stock/DPS                  A harassment    B harassment     Total take         stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale.................................  Hawaii DPS + Mexico DPS................               2              14              16              <1
Minke Whale....................................  Alaska.................................               2               6               8          \1\ NA
Dall's Porpoise................................  Alaska.................................              10             173             183             1.4
Harbor Porpoise................................  Southeast Alaska.......................               5              69              74               7
Killer Whale...................................  Eastern North Pacific, Northern                       2              90              92            2.91
                                                  Residents, Southeast Alaska + Eastern
                                                  North Pacific, Alaska Residents + West
                                                  Coast Transients + Gulf, Aleutian,
                                                  Bering Transients.
Harbor Seal....................................  Alaska--Lynn Canal/Stephens Passage....             203           2,451           2,654            19.9
Steller Sea Lion...............................  Eastern US + Western US................               2             211             213              <1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Alaska SAR does not have an estimated population size for the Alaska stock of minke whales due only a portion of the stock's range being surveyed
  and such few whales seen during stock abundance surveys.

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,

[[Page 23639]]

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 MOS implementation, 
which may consider such things as cost and impact on operations.
    NMFS proposed the following mitigation measures be implemented for 
MOS's pile installation and removal activities.

Mitigation Measures

    MOS must follow mitigation measures as specified below:
     Ensure that construction supervisors and crews, the 
monitoring team, and relevant MOS staff are trained prior to the start 
of all pile driving 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;
     Employ Protected Species Observers (PSOs) and establish 
monitoring locations as described in the application and the IHA. MOS 
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;
     The placement of the PSOs during all pile driving and 
removal activities will ensure that the entire shutdown zone is visible 
during pile driving activities. Should environmental conditions 
deteriorate such that marine mammals within the entire shutdown zone 
will not be visible (e.g., fog, heavy rain), pile driving and removal 
must be delayed until the PSO is confident marine mammals within the 
shutdown zone could be detected;
     Monitoring must take place from 30 minutes prior to 
initiation of pile driving activity (i.e., pre-clearance monitoring) 
through 30 minutes post-completion of pile driving activity;
     Pre-start clearance monitoring must be conducted during 
periods of visibility sufficient for the lead PSO to determine that the 
shutdown zones indicated in Table 9 are clear of marine mammals. Pile 
driving may commence following 30 minutes of observation when the 
determination is made that the shutdown zones are clear of marine 
mammals;
     MOS 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;
     If a marine mammal is observed entering or within the 
shutdown zones indicated in Table 9, pile driving must be delayed or 
halted. If pile driving is delayed or halted due to the presence of a 
marine mammal, the activity may not commence or resume until either the 
animal has voluntarily exited and been visually confirmed beyond the 
shutdown zone (Table 9) or 15 minutes have passed without re-detection 
of the animal; and
     As proposed by MOS, in water activities will take place 
only between civil dawn and civil dusk and for a limited duration after 
dusk with lighting when PSOs can effectively monitor for the presence 
of marine mammals; during conditions with a Beaufort Sea State of 4 or 
less; when the entire shutdown zone and adjacent waters are visible 
(e.g., monitoring effectiveness in not reduced due to rain, fog, snow, 
etc.).

Shutdown Zones

    MOS will establish shutdown zones for all pile driving 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 zone for each 
pile size/type and driving method where applicable, as shown in Table 
9.
    For in-water heavy machinery activities other than pile driving, if 
a marine mammal comes within 10 m, work generating underwater noise 
will stop and vessels will reduce speed to the minimum level required 
to maintain steerage and safe working conditions. A 10 m shutdown zone 
would also serve 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 9 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, in-water 
activities will continue and the animal's presence within the estimated 
harassment zone will be documented.
    MOS 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 MOS or its designated officials, the 
in-water

[[Page 23640]]

activity will be allowed to continue until the safety concern has been 
addressed, and the animal will be continuously monitored.

                              Table 9--Proposed Shutdown Zones and Monitoring Zones
----------------------------------------------------------------------------------------------------------------
             Activity                                    Minimum shutdown zone
----------------------------------------------------------------------------------------------------
                                        Low-         Mid-        High-                                Harassment
                                     frequency    frequency    frequency                                 zone
                                        (LF)         (MF)         (HF)        Phocid      Otariid
                                     cetaceans    cetaceans    cetaceans
----------------------------------------------------------------------------------------------------------------
36-in to 48-in steel pile **,             2,350           85        2,795        1,260           95        1,585
 Impact Installation..............
24-in steel pile, Impact                  1,250           45        1,485          670           50          860
 Installation.....................
Up to 30-in steel pile *,                    15           10           20           10           10        3,985
 Vibratory Installation and
 Removal..........................
36-in steel pile **, Vibratory               70           10          100           40           10       21,545
 Installation.....................
14-in timber pile, Vibratory                 15           10           25           10           10        3,415
 Removal..........................
----------------------------------------------------------------------------------------------------------------
* Includes piles sizes: 10.75-in, 14-in, 16-in, 20-in, 24-in, 28-in, and 30-in.
** Includes pile sizes: 36-in, 42-in, and 48-in.

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

Proposed Monitoring and Reporting

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

Visual Monitoring

    Marine mammal monitoring must be conducted in accordance with the 
conditions in this section and the IHA. Marine mammal monitoring during 
pile driving activities would be conducted by PSOs meeting NMFS' 
following requirements:
     Independent PSOs (i.e., not construction personnel) who 
have no other assigned tasks during monitoring periods would be used;

[[Page 23641]]

     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;
     Other PSOs may substitute education (degree in biological 
science or related field) or training for experience; and
     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 must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to 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
     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.
     MOS must employ up to five PSOs during all pile driving 
activities 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.
     MOS must establish the following monitoring locations with 
the best views of monitoring zones as described in the IHA and 
Application.
     Up to five 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 impact hammering monitoring zone and the 
Level A harassment Shutdown Zones. The stations will be at the Railroad 
Dock, Yakutania Point, and Dyea Point. The vibratory monitoring zone 
will be monitored using PSOs stationed on boats anchored near the 
shoreline. 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 cells phones for maintaining contact with 
work crews.
    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.
    MOS shall conduct briefings between construction supervisors and 
crews, PSOs, MOS 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.

Acoustic Monitoring

    Acoustic monitoring will be conducted during in-water pile 
installation and removal, for each of the three scenarios (impact 
installation of steel piles, vibratory installation and removal of 
steel piles, and vibratory removal of timber piles). Collection of the 
acoustic data will be accomplished using a minimum of two hydrophones. 
At least one land-based microphone would also be deployed to record 
airborne sound levels. For underwater acoustic monitoring, the 
hydrophones will be placed such that there is a direct line of acoustic 
transmission through the water column between the impact or vibratory 
hammer and the hydrophones, without any interposing structures 
(including other piles) that could impede sound transfer, when 
possible. All acoustical recordings will be conducted at least 1 meter 
below the water surface and 1 meter above the sea floor, or as 
applicable to optimize sound recordings in the nearshore environment. 
Background noise recordings (in the absence of pile-related work) will 
also be made during the study to provide a baseline background noise 
profile.
    All sensors, signal conditioning equipment, and sampling equipment 
will be calibrated at the start of the monitoring period to National 
Institute of Standards and Technology standards and will be rechecked 
at the start of each day.
    A stationary two-channel hydrophone recording system will be 
deployed to record continuous sound associated with pile driving and 
removal activities during the monitoring period. Key methodological 
details are as follows:
     Prior to monitoring, water depth measurements will be made 
to ensure that hydrophones will not drag on the bottom during tidal 
changes. The hydrophones will be placed at least 1 meter below the 
surface and 1 meter above the seafloor. The depth with respect to the 
bottom may vary somewhat due to tidal changes and current effects.
     One hydrophone will be deployed to maintain a constant 
distance of approximately 10 meters from the pile-related noise source, 
and the other would be at a further distance from the pile-related 
noise source.
     The hydrophones, signal conditioning, and recording 
equipment will be configured to acquire maximum source levels without 
clipping recorded data.
    Post-analysis of underwater sound level signals would include the 
following:
     Impact Pile Driving:
    1. Determination of the maximum absolute value of the instantaneous 
pressure within each strike.
    2. RMS value for the period of which 90 percent of the energy is 
represented (RMS 90, 5 percent to 95 percent) for each absolute peak 
pile strike.
    3. Peak SPL and pulse duration for each pile strike.
    4. Mean and standard deviation/error of the RMS 90 percent for all 
pile strikes of each pile.
    5. Rise time.
    6. Number of strikes per pile and per day.
    7. Sound exposure level (SEL) of the single pile strike with the 
absolute peak (PK), mean SEL.
    8. Minimum, maximum, mean, and median cumulative SEL (cumulative 
SEL = single strike SEL + 10*LOG (number of pile strikes)).
    9. Frequency spectrum, between 20 Hz and 20 kHz, for up to eight 
successive strikes with similar sound level.
     Vibratory Pile Driving and Removal:
    1. RMS values (median, standard deviation/error, minimum, and 
maximum) for each recorded pile. The 10-second, RMS-averaged values 
will be used for determining the source value and extent of the 120 dB 
underwater isopleth.
    2. Frequency spectra will be provided for each functional hearing 
group as

[[Page 23642]]

outlined in NOAA's 2018 guidance (NOAA, 2018).
    3. All underwater source levels will be standardized to a reference 
distance of 10 meters (33 feet).
     Post-analysis of airborne noise will be presented in an 
unweighted format, and will include the following:
    1. The unweighted RMS values (average, minimum, and maximum) for 
each recorded pile. The average values will be used for determining the 
extent of the airborne isopleths relative to species specific criteria.
    2. Frequency spectra will be provided from 10 Hz to 20 kHz for 
representative pile-related activity.
    3. All airborne source levels will be standardized to a reference 
distance of approximately 15 meters (50 feet).
     Acoustic monitoring will be performed using a standardized 
method that will facilitate comparisons with other studies. In the 
event that pile-related noise trends toward consistently surpassing 
calculated levels, NMFS will be contacted immediately to revise 
Shutdown Zones as needed.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance 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:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact or vibratory) and the total 
equipment duration for vibratory removal for each pile or total number 
of strikes for each pile (impact driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information:
     Name of PSO who sighted the animal(s) and PSO location and 
activity at the time of sighting;
     Time of sighting;
     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;
     Distance and bearing of each marine mammal observed 
relative to the pile being driven for each sightings (if pile driving 
was occurring at time of sighting);
     Estimated number of animals (min/max/best estimate);
     Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition, sex class, etc.);
     Animal's closest point of approach and estimated time 
spent within the harassment zone;
     Description of any marine mammal behavioral observations 
(e.g., observed behaviors such as feeding or traveling), including an 
assessment of behavioral responses thought to have resulted from the 
activity (e.g., no response or changes in behavioral state such as 
ceasing feeding, changing direction, flushing, or breaching);
     Number of marine mammals detected within the harassment 
zones and shutdown zones; by species;
     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; and
     If visibility degrades to where PSO(s) cannot view the 
entire harassment zones, additional PSOs may be positioned so that the 
entire width is visible, or work will be halted until the entire width 
is visible to ensure that any humpback whales entering or within the 
harassment zone are detected by PSOs.
    If no comments are received from NMFS within 30 days, the draft 
final report will constitute the final report. If comments are 
received, a final report addressing NMFS comments must be submitted 
within 30 days after receipt of comments.

Acoustic Monitoring Report

    The Acoustic Monitoring Report must include:
     Type and size of pile being driven, substrate type, method 
of driving during recordings (e.g., hammer model, energy), and total 
pile driving duration;
     Whether a sound attenuation device is used and, if so, a 
detailed description of the device and the duration of its use per 
pile;
     A description of the sound monitoring equipment, including 
a detailed description of the depths and locations of the hydrophones 
relative to the pile being driven;
     For impact pile driving: Number of strikes and strike 
rate, depth of substrate to penetrate; pulse duration and mean, median, 
and maximum sound levels (dB re: 1 [micro]Pa); root mean square sound 
pressure level (SPLRMS), cumulative sound exposure level 
(SELcum), peak sound pressure level (SPLpeak), 
and single strike exposure sound level (SEL s-s);
     For vibratory driving/removal (per pile): Duration of 
driving per pile; mean, median, and maximum sound levels (dB re: 1 
[micro]Pa): Root mean square sound pressure level (SPLRMS), 
cumulative sound exposure level (SELcum) (and timeframe over 
which the sound is averaged);
     One-third octave band spectrum and power spectral density 
plot for each pile monitored and average spectrum for each type of 
driving (i.e. impact, vibratory of steel, vibratory of timber); and,
     Environmental data, including but not limited to, the 
following: wind speed and direction, air temperature, humidity, surface 
water temperature, water depth (at the pile and hydrophone locations), 
characteristics of the bottom substrate into which the pile was driven, 
wave height, weather conditions, and other factors that could 
contribute to influencing the airborne and underwater sound levels 
(e.g., aircraft, boats, etc.).

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the MOS must immediately 
cease the specified activities and report the incident to the Office of 
Protected Resources (OPR) ([email protected]), NMFS and 
to the Alaska Regional Stranding Coordinator as soon as feasible. If 
the death or injury was clearly caused by the specified activity, MOS 
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 MOS must not resume their activities until notified by 
NMFS. The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;

[[Page 23643]]

     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, our analysis applies to all species listed in 
Table 2 for which take could occur, given that NMFS expects the 
anticipated effects of the proposed pile driving/removal on different 
marine mammal stocks to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis.
    Pile driving 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 Level A harassment from underwater sounds 
generated by pile driving. 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, limited take by Level A harassment is anticipated 
for humpback whales, minke whales, killer whales, harbor porpoise, and 
Steller sea lion due to the application of planned mitigation measures, 
such as shutdown zones that encompass the Level A harassment zones for 
these species and the rarity of these species near the action area. 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 all species, as there is 
potential for these species to be in the area. There is the possibility 
that an animal could enter a Level A harassment zone without being 
detected, and remain within that zone for a duration long enough to 
incur PTS. However, Level A harassment of these species is proposed to 
be conservative. 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 low for both marine mammal stocks and species except 
harbor seals as they are common in the area. 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.
    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 
adversely affect rates of recruitment or survival of the species or 
stock.
    The Level A harassment zones identified in Table 6 are based upon 
an animal's exposure to pile driving of up to 5 steel piles or 18 
timber piles removed per day. Given the short duration to impact drive 
or vibratory install or extract 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 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.
    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. Level A and Level B harassment will be reduced to 
the level of least practicable adverse impact through use of mitigation 
measures described herein. Further, the amount of take proposed to be 
authorized is small when compared to stock abundance.
    Behavioral responses of marine mammals to pile driving and removal 
in Taiya Inlet 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 and removal would occur for only a portion of 
the project's duration, any harassment occurring would be temporary. 
Additionally, many of the species present in region would only be

[[Page 23644]]

present temporarily based on seasonal patterns or during transit 
between other habitats. These temporarily present species would be 
exposed to even smaller periods of noise-generating activity, further 
decreasing the impacts.
    For all species, there are no known BIA near the project area that 
would be impacted by MOS's planned activities. While there is a Steller 
sea lion haulout at the end of Taiya inlet at Taiya point, this is 
approximately 13,300-m from the project site. Additionally, there is a 
rookery at Gran Point, which is Steller sea lion critical habitat, 
though this is outside the project area around 24 miles (38.6 km) from 
Skagway. Lastly, there is a summer feeding ground for humpback whales 
in Lynn Canal, however this is outside of Taiya Inlet, and 
approximately 50 miles (80.5 km) from Skagway.
    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 will 
have only minor, short-term effects on individuals. The specified 
activities are not expected to impact rates of recruitment or survival 
and will therefore not result in population-level impacts.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     Authorized Level A harassment would be very small amounts 
and of low degree;
     For all species, Taiya Inlet is a very small and 
peripheral part of their range;
     The intensity of anticipated takes by Level B harassment 
is 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;
     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;
     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;
     The lack of anticipated significant or long-term negative 
effects to marine mammal habitat; and
     MOS 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 from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted previously, only small numbers of incidental take may be 
authorized under 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 is below one-third of 
the estimated stock abundance for all species. 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.
    The most recent estimate for the Alaska stock of Dall's porpoise 
was 13,110 animals, however this number just accounts for a portion of 
the stock's range. Therefore, the 183 takes of this stock proposed for 
authorization is believed to be an even smaller portion of the overall 
stock abundance.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    In the Skagway area, sea lions and harbor seals are available for 
subsistence harvest authorized under the MMPA. The subsistence areas 
used by the Hoonah and Angoon communities are in the vicinity of the 
project area, but will not directly overlap with the project areas. 
During subsistence harvest in Southeast Alaska in 2012, the most recent 
year of available data from the Alaska Department of Fish and Game, 595 
harbor seals were taken, while only 9 sea lions were taken in the 
region (Wolfe et al., 2013). The proposed Project at worst may cause 
short-term disturbance to sea lions and harbor seals in the area.
    The proposed activity will take place in Taiya Inlet, and no 
activities overlap with subsistence hunting areas; therefore, there are 
no relevant subsistence uses of marine mammals adversely impacted by 
this action. 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 to impact subsistence harvest of 
marine mammals in the region because:
     Construction activities are localized and temporary;

[[Page 23645]]

     Mitigation measures will be implemented to minimize 
disturbance of marine mammals in the action area; and,
     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 there will 
not be an unmitigable adverse impact on subsistence uses from MOS'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 consults internally whenever we propose to authorize take for 
endangered or threatened species, in this case with the Alaska Regional 
Office.
    NMFS is proposing to authorize take of the Central North Pacific 
stock of humpback whale and the Western US stock of Steller sea lion, 
which are listed or include individuals that are listed under the ESA.
    The Permits and Conservation Division has requested initiation of 
section 7 consultation with the Alaska Region 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 an IHA to MOS for conducting construction in Skagway, Alaska 
provided the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated. A draft of the proposed IHA can be found 
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

Request for Public Comments

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

    Dated: April 13, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-08186 Filed 4-17-23; 8:45 am]
BILLING CODE 3510-22-P