60652 Federal Register / Vol. 88, No. 170 / Tuesday, September 5, 2023 / Notices 

https://meetings.npfmc.org/Meeting/ 

Details/3006. 

Council address: North Pacific 

Fishery Management Council, 1007 W 

3rd Ave, Suite 400, Anchorage, AK 

99501–2252; telephone: (907) 271–2809. 

Instructions for attending the meeting 

are given under SUPPLEMENTARY

INFORMATION, below. 

FOR FURTHER INFORMATION CONTACT: Sara 

Cleaver, Council staff; telephone: (907) 

271–2809; email: sara.cleaver@noaa.gov 

or Diana Stram, Council staff; email 

diana.stram@noaa.gov. For technical 

support, please contact our 

administrative staff; email: 

npfmc.admin@noaa.gov. 

SUPPLEMENTARY INFORMATION: 

Agenda 

Tuesday, September 19, 2023 Through 

Friday, September 22, 2023 

The Bering Sea and Aleutian Islands 

(BSAI) and Gulf of Alaska (GOA) 

Groundfish Plan Teams will meet to 

review and discuss issues of importance 

to both Plan Teams, including but not 

limited to: Economic and 

Socioeconomic Profile update, 

Ecosystem Status Report climate update, 

ecosystem surveys, bottom trawl 

surveys (BTS), longline survey, updates 

on model progress for stock assessments 

to be presented in November, and 

proposed harvest specifications. The 

agenda is subject to change, and the 

latest version will be posted at https:// 

meetings.npfmc.org/Meeting/Details/ 

3006 prior to the meeting, along with 

meeting materials. 

Connection Information 

You can attend the meeting online 

using a computer, tablet, or smartphone; 

or by phone only. Connection 

information will be posted online at: 

https://meetings.npfmc.org/Meeting/ 

Details/3006. 

Public Comment 

Public comment letters should be 

submitted electronically via the 

electronic agenda at https://

meetings.npfmc.org/Meeting/Details/ 

3006. 

Authority: 16 U.S.C. 1801 et seq. 

Dated: August 30, 2023. 

Rey Israel Marquez, 

Acting Deputy Director, Office of Sustainable 

Fisheries, National Marine Fisheries Service. 

[FR Doc. 2023–19083 Filed 9–1–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD165] 

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; issuance of an incidental 

harassment authorization. 

SUMMARY: In accordance with the 

regulations implementing the Marine 

Mammal Protection Act (MMPA) as 

amended, notification is hereby given 

that NMFS has issued an Incidental 

Harassment Authorization (IHA) to 

Municipality of Skagway (MOS) to 

incidentally harass marine mammals 

during construction associated with the 

Ore Terminal redevelopment project in 

Skagway, Alaska. 

DATES: This authorization is effective 

from October 1, 2023 through 

September 30, 2024. 

ADDRESSES: Electronic copies of the 

application and supporting documents, 

as well as a list of the references cited 

in this document, may be obtained 

online at: https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorizationmunicipality-skagways-skagway-oreterminal-redevelopment. In case of 

problems accessing these documents, 

please call the contact listed below. 

FOR FURTHER INFORMATION CONTACT: 

Jenna Harlacher, Office of Protected 

Resources, NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 

Background 

The MMPA prohibits the ‘‘take’’ of 

marine mammals, with certain 

exceptions. Sections 101(a)(5)(A) and 

(D) of the MMPA (16 U.S.C. 1361 et 

seq.) direct the Secretary of Commerce 

(as delegated to NMFS) to allow, upon 

request, the incidental, but not 

intentional, taking of small numbers of 

marine mammals by U.S. citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

proposed or, if the taking is limited to 

harassment, a notice of a proposed IHA 

is provided to the public for review. 

Authorization for incidental takings 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s) and will not have 

an unmitigable adverse impact on the 

availability of the species or stock(s) for 

taking for subsistence uses (where 

relevant). Further, NMFS must prescribe 

the permissible methods of taking and 

other ‘‘means of effecting the least 

practicable adverse impact’’ on the 

affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance, and on the 

availability of the species or stocks for 

taking for certain subsistence uses 

(referred to in shorthand as 

‘‘mitigation’’); and requirements 

pertaining to the mitigation, monitoring 

and reporting of the takings are set forth. 

The definitions of all applicable MMPA 

statutory terms cited above are included 

in the relevant sections below. 

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. The 

proposed IHA published for public 

comment on April 18, 2023 (88 FR 

23627). 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 Activity 

MOS plans to redevelop the Skagway 

Ore Terminal in Skagway, Alaska. The 

project will cover construction from fall 

2023 through spring 2024 to avoid 

construction during cruise ship season 

with a maximum of 196 days of pile 

installation and removal. While the total 

number of estimated pile driving days is 

213, some days will include both impact 

and vibratory pile driving, reducing the 

maximum number of workdays to 196 

(Table 1). This project involves 

installation and removal of 36 

temporary steel pile guides, removal of 

692 piles, and installation of 244 

permanent steel piles. The IHA would 

be effective from October 1, 2023 

through September 30, 2024. MOS will 

conduct a total of 142 days of vibratory 

pile installation and removal and 71 

days of impact pile driving, which was 

updated to reflect a more accurate 

number of days from the proposed 

notice of IHA. Sounds resulting from 

pile installation and removal may result 

in the incidental take of marine 


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mammals by Level A and Level B harassment in the form of auditory 

injury or behavioral harassment. 

TABLE 1—PILE INSTALLATION METHODS AND DURATIONS +

Pile size, method Number of 

piles 

Duration/strikes 

per pile 

Piles driven/ 

day 

Estimated 

days 1

36-in to 48-in steel pile,** Impact Installation ........................................... 74 1800 strikes .......... 2 34 

24-in steel pile, Impact Installation ............................................................ 170 700 strikes ........... 5 37

Up to 30-in steel pile,* Vibratory Installation and Removal ...................... 511 45 min .................. 5 103 

36-in to 48 in steel pile,** Vibratory Installation ........................................ 74 45 min .................. 5 15 

14-in timber pile, Vibratory Removal ......................................................... 423 21 min .................. 18 24 

* 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. 

1Estimated days are based on individual days of work, in reality work could occur on the same day reducing the total number of workdays to 

196. + Changes were made to this table from proposed to final including: MOS updating their estimated work days and including temporary pile installation and removal in the up to 30-in steel piles. 

A further detailed description of the 

planned construction project is 

provided in the Federal Register notice 

for the proposed IHA (88 FR 23627, 

April 18, 2023). Please refer to that 

Federal Register notice for the 

description of the specified activity. 

Mitigation, monitoring, and reporting 

measures are described in detail later in 

this document (please see Mitigation 

and Monitoring and Reporting). 

Comments and Responses 

A notice of NMFS’ proposal to issue 

an IHA to MOS was published in the 

Federal Register on April 18, 2023 (88 

FR 23627). That notice described, in 

detail, MOS activities, the marine 

mammal species that may be affected by 

the activities, and the anticipated effects 

on marine mammals. During the 30-day 

public comment period only nonsubstantive comments were received 

and are not discussed further. 

Changes From the Proposed IHA to 

Final IHA 

Changes were made between 

publication of the notice of proposed 

IHA and this notice of final IHA. 

Changes have been made to correct 

typographical errors in pile numbers in 

the proposed Federal Register notice. 

The effective dates of the IHA, the 

maximum number of days of pile 

driving activity, and the Protected 

Species Observer (PSO) monitoring 

locations have been updated at the 

request of MOS. Harbor porpoise stock 

abundance was corrected and language 

limiting monitoring to a specific 

Beaufort sea state was removed. 

Additionally, take by Level B and Level 

A harassment has been updated for 

harbor porpoise, Dall’s porpoise, harbor 

seal, and Steller sea lion to reflect the 

updated number of workdays and 

correct mistakes in ensonified area 

calculations. 

Since the Federal Register notice of 

the proposed IHA was published (88 FR 

23627, April 18, 2023), NMFS published 

the final 2022 Alaska and Pacific Stock 

Assessment Reports (SARs), which 

describe revised stock structures under 

the MMPA for humpback whales and 

southeast Alaska harbor porpoise 

(Carretta et al., 2023; Young et al., 

2023). In the notice of proposed IHA, we 

explained that although we typically 

consider updated peer-reviewed data 

provided in draft SARs to be the best 

available science, and use the 

information accordingly, we make 

exception for proposed revised stock 

structures. Upon finalization of these 

revised stock structures, we have made 

appropriate updates, including 

description of the potentially affected 

stocks (see Table 2), attribution of take 

numbers to stock (see Estimated Take), 

and by updating our analyses to ensure 

the necessary determinations are made 

for the new stocks (see Negligible 

Impact Analysis and Determination and 

Small Numbers). 

Description of Marine Mammals in the 

Area of Specified Activities 

Sections 3 and 4 of the application 

summarize available information 

regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history of the potentially 

affected species. NMFS fully considered 

all of this information, and we refer the 

reader to these descriptions, instead of 

reprinting the information. Additional 

information regarding population trends 

and threats may be found in NMFS’ 

Stock Assessment Reports (SARs; 

https://www.fisheries.noaa.gov/

national/marine-mammal-protection/

marine-mammal-stock-assessments) 

and more general information about 

these species (e.g., physical and 

behavioral descriptions) may be found 

on NMFS’ website (https://

www.fisheries.noaa.gov/find-species). 

Table 2 lists all species or stocks for 

which take is expected and authorized 

to be authorized for this activity, and 

summarizes information related to the 

population or stock, including 

regulatory status under the MMPA and 

Endangered Species Act (ESA) and 

potential biological removal (PBR), 

where known. PBR is defined by the 

MMPA as the maximum number of 

animals, not including natural 

mortalities, that may be removed from a 

marine mammal stock while allowing 

that stock to reach or maintain its 

optimum sustainable population (as 

described in NMFS’ SARs). While no 

serious injury or mortality is anticipated 

or authorized here, PBR and annual 

serious injury and mortality from 

anthropogenic sources are included here 

as gross indicators of the status of the 

species or stocks and other threats. 

Marine mammal abundance estimates 

presented in this document represent 

the total number of individuals that 

make up a given stock or the total 

number estimated within a particular 

study or survey area. NMFS’ stock 

abundance estimates for most species 

represent the total estimate of 

individuals within the geographic area, 

if known, that comprises that stock. For 

some species, this geographic area may 

extend beyond U.S. waters. All managed 

stocks in this region are assessed in 

NMFS’ 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: 

https://www.fisheries.noaa.gov/

national/marine-mammal-protection/

marine-mammal-stock-assessments. 


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TABLE 2—SPECIES LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 1

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 2

PBR Annual 

M/SI 3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) 

Family Balaenopteridae 

(rorquals): 

Humpback whale .............. Megaptera novaeanglinae ...... Hawai1i .................................... -,-,N 11,278 (0.56, 7,265, 2020) .... 127 27.09 

Mexico-North Pacific .............. T,D,Y 918 (0.217, UNK, 2006) ......... UNK 0.57 

Minke whale ..................... Balaenoptera acutorostra ....... Alaska ..................................... -,-,N UNK ........................................ NA 0 

Superfamily Odontoceti (toothed whales, dolphins, and porpoises) 

Family Delphinidae: 

Killer whale ....................... Orca orcinus ........................... Eastern North Pacific, Norther 

Residents, Southeast Alaska.

-,-,N 302 (N/A, 302, 2018) ............. 2.2 0.2 

Eastern North Pacific Alaska 

Residents.

-,-,N 1,920 (N/A, 1,920, 2019) ....... 19 1.3 

West Coast Transients ........... -,-,N 349 (N/A, 349, 2018) ............. 3.5 0.4 

Gulf, Aleutian, Bering Transients.-,-,N 587 (N/A, 587, 2020) ............. 5.9 0.8 

Family Phocoenidae (porpoises): 

Harbor Porpoise ............... Phocoena phocoena .............. Northern Southeast Alaska Inland Waters.-,-,N 1,619 (0.26, 1,250, 2019) ...... 13 5.6 

Dall’s porpoise4 ................ Phocoenoides dalli ................. Alaska ..................................... -,-,N 15,432 (0.28, 13, 110, 2021) 131 37 

Order Carnivora—Superfamily Pinnipedia 

Family Otariidae (eared seals 

and sea lions): 

Steller sea lion ........................ Eumetopias jubatus ................ Western Stock ........................ E,D,Y 52,932 (N/A, 52,932, 2019) ... 318 254 

Eastern Stock ......................... -,-,N 43,201 (N/A, 43,201, 2017) ... 2,592 112 

Family Phocidae (earless 

seals): 

Harbor seal ....................... Phoca vituline richardii ........... Alaska-Lynn Canal/Stephens 

Passage.

-,-,N 13,388 (N/A, 11,867, 2016) ... 214 50 

1Endangered 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-assessmentreports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 3These 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. 4Previous 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. 

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 authorized. 

A detailed description of the species 

likely to be affected by MOS’s 

construction project, including brief 

introductions to the species and 

relevant stocks as well as available 

information regarding population trends 

and threats, and information regarding 

local occurrence, were provided in the 

Federal Register notice for the proposed 

IHA (88 FR 23627, April 18, 2023); since 

that time, we are not aware of any 

changes in the status of these species 

and stocks; therefore, detailed 

descriptions are not provided here. 

However, there was a mistake in the 

harbor porpoise stock abundance listed 

in the notice for the proposed IHA, and 

the value was updated in this notice of 

final IHA. Please refer to that Federal 

Register notice for these descriptions. 

Please also refer to the NMFS website 

(https://www.fisheries.noaa.gov/findspecies) for generalized species 

accounts. 

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 lowfrequency 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 


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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 whales) ..................................................................................................................... 7 Hz to 35 kHz. 

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) ........................................... 150 Hz to 160 kHz. 

High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. 

australis).

275 Hz to 160 kHz. 

Phocid pinnipeds (PW) (underwater) (true seals) ................................................................................................................... 50 Hz to 86 kHz. 

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) .............................................................................................. 60 Hz to 39 kHz. 

* 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 

(Hemila ̈ 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 

The effects of underwater noise from 

the MOS’s pile driving activities have 

the potential to result in behavioral 

harassment of marine mammals in the 

vicinity of the project area. The notice 

of the proposed IHA (88 FR 23627, April 

18, 2023) included a discussion of the 

effects of anthropogenic noise on marine 

mammals and the potential effects of 

underwater noise from the MOS’s pile 

driving activities on marine mammals 

and their habitat. That information and 

analysis is incorporated by reference 

into this final IHA determination and is 

not repeated here; please refer to the 

notice of the proposed IHA (88 FR 

23627, April 18, 2023). 

Estimated Take of Marine Mammals 

This section provides an estimate of 

the number of incidental takes 

authorized 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 mitigation and monitoring 

measures are expected to minimize the 

severity of the taking to the extent 

practicable. As described previously, no 

serious injury or mortality is anticipated 

or authorized for this activity. Below, 

we describe how the take numbers are 

estimated. 

For acoustic impacts, generally 

speaking, we estimate take by 

considering: (1) acoustic thresholds 

above which NMFS believes the best 

available science indicates marine 

mammals will be behaviorally harassed 

or incur some degree of permanent 

hearing impairment; (2) the area or 

volume of water that will be ensonified 

above these levels in a day; (3) the 

density or occurrence of marine 

mammals within these ensonified areas; 

and, (4) the number of days of activities. 

We note that while these factors can 

contribute to a basic calculation to 

provide an initial prediction of potential 

takes, additional information that can 

qualitatively inform take estimates is 

also sometimes available (e.g., previous 

monitoring results or average group 

size). Below, we describe the factors 

considered here in more detail and 

present the take estimates. 

Acoustic Thresholds 

NMFS recommends the use of 

acoustic thresholds that identify the 

received level of underwater sound 

above which exposed marine mammals 

would be reasonably expected to be 

behaviorally harassed (equated to Level 

B harassment) or to incur 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-meansquared pressure received levels (RMS 

SPL) of 120 dB (referenced to 1 

micropascal (re 1 mPa)) for continuous 

(e.g., vibratory pile driving, drilling) and 

above RMS SPL 160 dB re 1 mPa for nonexplosive impulsive (e.g., seismic 

airguns) or intermittent (e.g., scientific 

sonar) sources. Generally speaking, 

Level B harassment take estimates based 

on these behavioral harassment 

thresholds are expected to include any 

likely takes by temporary threshold shift 

(TTS) as, in most cases, the likelihood 


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of TTS occurs at distances from the 

source less than those at which 

behavioral harassment is likely. TTS of 

a sufficient degree can manifest as 

behavioral harassment, as reduced 

hearing sensitivity and the potential 

reduced opportunities to detect 

important signals (conspecific 

communication, predators, prey) may 

result in changes in behavior patterns 

that would not otherwise occur. 

MOS’s 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 mPa are 

applicable. 

Level A Harassment—NMFS’ 

Technical Guidance for Assessing the 

Effects of Anthropogenic Sound on 

Marine Mammal Hearing (Version 2.0) 

(Technical Guidance, 2018) identifies 

dual criteria to assess auditory injury 

(Level A harassment) to five different 

marine mammal groups (based on 

hearing sensitivity) as a result of 

exposure to noise from two different 

types of sources (impulsive or nonimpulsive). MOS’s 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: 

https://www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

marine-mammal-acoustic-technicalguidance. 

TABLE 4—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset acoustic thresholds * 

(received level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans ...................................... Cell 1: Lpk,flat: 219 dB; LE,LF,24h: 183 dB ......................... Cell 2: LE,LF,24h: 199 dB. 

Mid-Frequency (MF) Cetaceans ...................................... Cell 3: Lpk,flat: 230 dB; LE,MF,24h: 185 dB ........................ Cell 4: LE,MF,24h: 198 dB. 

High-Frequency (HF) Cetaceans ..................................... Cell 5: Lpk,flat: 202 dB; LE,HF,24h: 155 dB ........................ Cell 6: LE,HF,24h: 173 dB. 

Phocid Pinnipeds (PW) (Underwater) ............................. Cell 7: Lpk,flat: 218 dB; LE,PW,24h: 185 dB ....................... Cell 8: LE,PW,24h: 201 dB. 

Otariid Pinnipeds (OW) (Underwater) ............................. Cell 9: Lpk,flat: 232 dB; LE,OW,24h: 203 dB ....................... Cell 10: LE,OW,24h: 219 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 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s. 

In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure 

is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ‘‘flat’’ is being 

included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated 

with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF 

cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level 

thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for 

action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. 

Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that are used in estimating the area 

ensonified above the acoustic 

thresholds, including source levels and 

transmission loss coefficient. 

The sound field in the project area is 

the existing background noise plus 

additional construction noise from the 

planned 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 Peak SPLs 

(dB) 

RMS SPLs 

(dB) 

SELss 

(dB) Source 

36-in to 48-in steel pile,** Impact Installation ....................................................... 210 193 183 Caltrans 2020. 

24-in steel pile, Impact Installation ....................................................................... 203 189 177 Caltrans 2020. 

Up to 30-in steel pile,* Vibratory Installation and Removal .................................. 196 159 NA Caltrans 2020. 

36-in to 48-in steel pile,** Vibratory Installation .................................................... 180 170 NA Caltrans 2015. 

14-in timber pile, Vibratory Removal ..................................................................... NA 158 NA Greenbusch 2018. 

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 


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spherical and cylindrical spreading loss 

conditions, which is the most 

appropriate assumption for MOS’s 

planned activities. The Level B 

harassment zones for the planned 

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 

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 AND AREAS FOR IMPACT AND VIBRATORY PILE DRIVING

Activity 

Level A harassment zone (m)/area ensonified (km2) 1 Level B 

harassment 

zone (m)/area 

ensonified 

(km2) 

LF cetacean MF cetacean HF cetacean Phocids Otariids 

36-in to 48-in steel pile,** Impact Installation ......................... 2,345.7/5.85 83.4/0.02 2,794.1/6.95 1,255.3/2.20 91.4/0.05 1,584.9/3.23 

24-in steel pile, Impact Installation ......................................... 1,245.8/2.16 44.3/0.01 1,483.9/2.88 666.7/0.88 48.5/0.01 857.7/1.23 

Up to 30-in steel pile,* Vibratory Installation and Removal .... 12.1/<0.01 1.1/<0.01 17.9/<0.01 7.4/<0.01 0.5/<0.01 3,981/9.08 

36-in to 48-in steel pile,** Vibratory Installation ...................... 65.6/0.01 5.8/<0.01 97/0.03 39.9/0.01 2.8/<0.01 21,544/20.36 

14-in timber pile, Vibratory Removal ...................................... 14.7/<0.01 1.3/<0.01 21.7/<0.01 8.9/<0.01 0.6/<0.01 3,414.5/8.06 

* 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. 

1Ensonified areas were updated from proposed to final to correct a mistake. 

Marine Mammal Occurrence 

In this section we provide information 

about the occurrence of marine 

mammals, including density or other 

relevant information which will inform 

the take calculations. 

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 sitespecific knowledge and professional 

judgement. Table 7 density estimates are 

calculated based on winter density 

estimates of Western Behm Canal. 

TABLE 7—DENSITY OF MARINE MAMMAL SPECIES IN THE PROJECT AREA

Species Density 

(per km2) 

Humpback Whale ....................... 0.0081 

Minke Whale ............................... 0.0017 

Dall’s Porpoise ............................ 0.1210 

Harbor Porpoise ......................... 0.0473 

Killer Whale ................................ 0.0041 

Harbor Seal ................................ 1.730 

Steller Sea Lion .......................... 0.0123 

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 authorized. 

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 few 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 activity is occurring. Some 

species were increased or reduced from 

the calculated take when it did not align 

with local sighting data. Steller sea lion 

take estimates are increased to one 

potential take per day and killer whale 

take estimates are increased based on 

sightings of groups of killer whales four 

to five times per year. Harbor seal take 

was reduced as the estimate was high 

for winter when the work will occur. 

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—AUTHORIZED AMOUNT OF TAKING AND PERCENT OF STOCK

Species Stock 

Take by 

Level A 

harassment 

Take by 

Level B 

harassment 

Total take Percent of 

stock 

Humpback Whale ...................................... Hawaii 3 ..................................................... 2 13 15 <1 

Mexico-North Pacific 3 .............................. 0 1 1 <1 


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TABLE 8—AUTHORIZED AMOUNT OF TAKING AND PERCENT OF STOCK—Continued 

Species Stock 

Take by 

Level A 

harassment 

Take by 

Level B 

harassment 

Total take Percent of 

stock 

Minke Whale ............................................. Alaska ....................................................... 2 6 8 1 NA 

Dall’s Porpoise .......................................... Alaska ....................................................... 43 193 2 236 1.8 

Harbor Porpoise ........................................ Southeast Alaska ..................................... 17 75 2 92 5.7 

Killer Whale ............................................... Eastern North Pacific, Northern Residents, Southeast Alaska + Eastern 

North Pacific, Alaska Residents + West 

Coast Transients + Gulf, Aleutian, Bering Transients.

2 90 92 2.91 

Harbor Seal ............................................... Alaska—Lynn Canal/Stephens Passage 193 2,760 2 2,953 22.1 

Steller Sea Lion ........................................ Eastern US + Western US ....................... 2 196 2 198 <1 

1Alaska 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. 2Take was updated to reflect updated workdays and corrected ensonified areas. 

3Take was updated and allocated for the revised stock structure in the 2022 SARs. 

Mitigation 

In order to issue an IHA under section 

101(a)(5)(D) of the MMPA, NMFS must 

set forth the permissible methods of 

taking pursuant to the activity, and 

other means of effecting the least 

practicable impact on the species or 

stock and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance, and on 

the availability of the species or stock 

for taking for certain subsistence uses. 

NMFS regulations require applicants for 

incidental take authorizations to include 

information about the availability and 

feasibility (economic and technological) 

of equipment, methods, and manner of 

conducting the activity or other means 

of effecting the least practicable adverse 

impact upon the affected species or 

stocks, and their habitat (50 CFR 

216.104(a)(11)). 

In evaluating how mitigation may or 

may not be appropriate to ensure the 

least practicable adverse impact on 

species or stocks and their habitat, as 

well as subsistence uses where 

applicable, NMFS considers two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat, as well as 

subsistence uses. This considers the 

nature of the potential adverse impact 

being mitigated (likelihood, scope, 

range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

implemented as planned), the 

likelihood of effective implementation 

(probability implemented as planned), 

and; 

(2) The practicability of the measures 

for applicant implementation, which 

may consider such things as cost, and 

impact on operations. 

NMFS requires 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 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 postcompletion 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 planned 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; 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 


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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 

meters (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 will 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 inwater 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 

activity will be allowed to continue 

until the safety concern has been 

addressed, and the animal will be 

continuously monitored. 

The large HF shutdown zones will be 

effectively monitored from the Kasidaya 

land based monitoring station and 

vessel traversing the south end of the 

largest Level B harassment zone. See the 

figures in MOS application for further 

details. 

TABLE 9—SHUTDOWN ZONES AND MONITORING ZONES

Activity 

Minimum shutdown zone 

Harassment 

zone Low-frequency 

(LF) 

cetaceans 

Mid-frequency 

(MF) 

cetaceans 

High-frequency 

(HF) 

cetaceans 

Phocid Otariid 

36-in to 48-in steel pile,** Impact Installation ............................................. 2,350 85 2,795 1,260 95 1,585 

24-in steel pile, Impact Installation ............................................................. 1,250 45 1,485 670 50 860 

Up to 30-in steel pile,* Vibratory Installation and Removal ........................ 15 10 20 10 10 3,985 

36-in to 48-in steel pile,** Vibratory Installation .......................................... 70 10 100 40 10 1 16,300 

14-in timber pile, Vibratory Removal .......................................................... 15 10 25 10 10 3,415 

* 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. 

1Shoreline of Taiya Inlet obstructs sound transmission and limits the extent of the Level B harassment zone. 

Protected Species Observers 

The placement of PSOs during all 

construction activities (described in the 

Monitoring and Reporting section) will 

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 will 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 will observe the 

shutdown and monitoring zones for a 

period of 30 minutes. The shutdown 

zone will 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 will be 

delayed or halted. If work ceases for 

more than 30 minutes, the pre-activity 

monitoring of the shutdown zones will 

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 will 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 will 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 

planned measures, as well as other 

measures considered by NMFS, NMFS 

has determined that the mitigation 

measures provide the means effecting 

the least practicable impact on the 

affected species or stocks and their 

habitat, paying particular attention to 


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rookeries, mating grounds, and areas of 

similar significance. 

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 will be conducted by 

PSOs meeting the following 

requirements: 

• Independent PSOs (i.e., not 

construction personnel) who have no 

other assigned tasks during monitoring 

periods; 

• At least one PSO will 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 will be 

designated. The lead observer will 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 

vibratory and impact hammering 

monitoring zones and the shutdown 

zones. The land based monitoring 

locations will be at the Railroad Dock, 

Yakutania Point, and Kasidaya. The 

larger monitoring zones will be 

monitored using PSOs in a mobile 

vessel traversing the south end of the 

monitoring zone in addition to the land 

based locations. All PSOs will 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 will be conducted 30 

minutes before, during, and 30 minutes 

after all in water construction activities. 

In addition, PSOs will record all 

incidents of marine mammal 

occurrence, regardless of distance from 

activity, and will 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 

will 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 will 

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 


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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 pilerelated 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 

(RMS90 (here forward referred to as 

SPLRMS), 5 percent to 95 percent) for 

each absolute peak pile strike. 

3. Mean and standard deviation/error 

of the SPLRMS percent for all pile strikes 

of each pile. 

4. Rise time. 

5. Number of strikes per pile and per 

day. 

6. Sound exposure level (SEL) of the 

single pile strike with the absolute peak 

(PK), mean SEL. 

7. Minimum, maximum, mean, and 

median cumulative SEL (cumulative 

SEL = single strike SEL + 

10*LOG10(number of pile strikes)). 

8. Frequency spectrum, between 20 

hertz (Hz) and 20 kilohertz (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 

outlined in NOAA’s 2018 guidance 

(NOAA, 2018). 

• All underwater source levels will be 

recorded as measured and could 

additionally 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 pilerelated 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 


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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 mPa); 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 mPa): 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.). 

• Sound measurement data shall be 

provided to NMFS in tabular 

spreadsheet format (Microsoft Excel or 

similar). 

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) 

(PR.ITP.MonitoringReports@noaa.gov), 

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; 

• 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., populationlevel 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 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 

Mitigation section). 

Take by Level A harassment is 

authorized 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 authorized 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 

authorized 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 


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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 breaks 

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 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 

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 

Biologically Important Areas (BIAs) 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 within 

designated 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 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 longterm 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 

monitoring and mitigation measures, 

NMFS finds that the total marine 

mammal take from the activity will have 

a negligible impact on all affected 

marine mammal species or stocks. 

Small Numbers 

As noted previously, only take of 

small numbers of marine mammals may 

be authorized under sections 

101(a)(5)(A) and (D) of the MMPA for 

specified activities other than military 

readiness activities. The MMPA does 

not define small numbers and so, in 

practice, where estimated numbers are 

available, NMFS compares the number 

of individuals taken to the most 

appropriate estimation of abundance of 

the relevant species or stock in our 

determination of whether an 

authorization is limited to small 

numbers of marine mammals. When the 

predicted number of individuals to be 

taken is fewer than one-third of the 

species or stock abundance, the take is 

considered to be of small numbers. 

Additionally, other qualitative factors 

may be considered in the analysis, such 

as the temporal or spatial scale of the 

activities. 

The amount of take NMFS is 

authorizing 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 


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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 authorized is believed to be an 

even smaller portion of the overall stock 

abundance. 

Likewise, there is no current or 

historical estimate of the Alaska minke 

whale stock, but minke whale 

abundance has been estimated to be 

over 1,000 whales in portions of Alaska 

(Muto et al., 2022) so the 8 takes 

proposed for authorization represent 

small numbers of this stock. 

Additionally, the range of the Alaska 

stock of minke whales is extensive, 

stretching from the Canadian Pacific 

coast to the Chukchi Sea, and DOT&PF’s 

project area impacts a small portion of 

this range. Therefore, the eight takes of 

minke whale proposed for authorization 

is small relative to estimated survey 

abundance, even if each proposed take 

occurred to a new individual. 

Based on the analysis contained 

herein of the planned activity (including 

the mitigation and monitoring 

measures) and the anticipated take of 

marine mammals, NMFS 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 project at worst 

may cause short-term disturbance to sea 

lions and harbor seals in the area. 

The 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 planned 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; 

• 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 

mitigation and monitoring measures, 

NMFS has determined that there will 

not be an unmitigable adverse impact on 

subsistence uses from MOS’s 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 plan to authorize take for 

endangered or threatened species, in 

this case with the Alaska Regional 

Office. 

NMFS is authorizing take of the 

Mexico-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 Permit and Conservation Division 

completed a Section 7 consultation with 

the Alaska Regional Office for the 

issuance of this IHA on August 23, 

2023. The Alaska Regional Office’s 

biological opinion states that the action 

is not likely to jeopardize the continued 

existence of the listed species. 

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 

determined that the issuance of the IHA 

qualifies to be categorically excluded 

from further NEPA review. 

Authorization 

As a result of these determinations, 

NMFS has issued an IHA to MOS for the 

potential harassment of small numbers 

of 7 marine mammal species incidental 

to the terminal redevelopment project in 

Skagway, Alaska that includes the 

previously explained mitigation, 

monitoring, and reporting requirements. 

The final IHA can be found at: https:// 

www.fisheries.noaa.gov/action/ 

incidental-take-authorizationmunicipality-skagways-skagway-oreterminal-redevelopment. 

Dated: August 29, 2023. 

Catherine Marzin, 

Acting Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2023–19029 Filed 9–1–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD310] 

Marine Mammals; File No. 27361 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; receipt of application. 

SUMMARY: Notice is hereby given that 

Brent Stewart, Ph.D., Brent S Stewart 

Associates, 3889 Creststone Place, San 


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