82326 Federal Register / Vol. 88, No. 225 / Friday, November 24, 2023 / Notices 

Dated: November 20, 2023. 

Rey Israel Marquez, 

Acting Deputy Director, Office of Sustainable 

Fisheries, National Marine Fisheries Service. 

[FR Doc. 2023–25964 Filed 11–22–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XC980] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to the U.S. Army 

Corps of Engineers Unalaska (Dutch 

Harbor) Channel Deepening Project 

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 the 

United States Army Corps of Engineers 

(Alaska District) (USACE) for 

authorization to take marine mammals 

incidental to Unalaska (Dutch Harbor) 

Channel Deepening in Iliuliuk Bay, 

Unalaska, Alaska. 

DATES: This Authorization is effective 

from January 1, 2024 through December 

31, 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-authorization-us-armycorps-engineers-unalaska-dutch-harborchannel. In case of problems accessing 

these documents, please call the contact 

listed below. 

FOR FURTHER INFORMATION CONTACT: Cara 

Hotchkin, 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 October 31, 2022, NMFS received 

a request from the United States Army 

Corps of Engineers—Alaska District 

(USACE) for an IHA to take marine 

mammals incidental to deepening the 

entrance to Iliuliuk Bay, adjacent to 

Dutch Harbor, Alaska. Following NMFS’ 

review of the application, USACE 

submitted supplemental information on 

November 28, 2022 and January 5, 2023. 

The application was deemed adequate 

and complete on March 2, 2023. The 

notice of the proposed IHA and request 

for comments was published on April 

11, 2023 (88 FR 21630). USACE’s 

request is for take of harbor seals (Phoca 

vitulina richardsi), Steller sea lions 

(Eumetopias jubatus), harbor porpoise 

(Phocoena phocoena), and humpback 

whales (Megaptera novaengliae) by 

Level A harassment and Level B 

Harassment. Neither USACE nor NMFS 

expect serious injury or mortality to 

result from this activity and, therefore, 

an IHA is appropriate. 

Description of the Specified Activity 

The USACE plans to deepen the 

entrance channel of Iliuliuk Bay by 

means of dredging and (if necessary) 

confined blasting of a 42-foot (ft) (12.8 

meter (m)) deep ‘‘bar’’ which currently 

restricts access to the port of Dutch 

Harbor, Alaska. Dutch Harbor is the 

only deep draft, year-round ice-free port 

along the 1,200-mile (1,931 km) 

Aleutian Island chain, providing vital 

services to vessels operating in both the 

North Pacific and the Bering Sea, and 

the depth of the bar currently restricts 

access for large vessels that may need to 

enter the port, particularly during 

extreme weather. The purpose of the 

project is to increase navigational safety 

and improve economic efficiencies into 

and out of Dutch Harbor via Iliuliuk 

Bay. 

Removal of the bar will involve 

dredging (via clamshell dredge or longreach excavator) an area approximately 

600 ft (182.9 m) by 600 ft (182.9 m), 

moving approximately 182,000 cubic 

yards (139,150 cubic meters) of 

sediment. Dredged material will be 

placed in the water immediately 

adjacent to the inside of the bar in 

approximately 100 ft (33.3 m) of water. 

If required to enable dredging, confined 

blasting (hereafter ‘‘blasting’’) involving 

drilled boreholes and multiple charges 

with microdelays between blasts will be 

used to break up the sediment. 

Safety restrictions impose some limits 

on blasting activity and potential 

mitigations available to protect marine 

mammals. The explosives cannot 

‘‘sleep’’ after being placed for longer 

than 24 hours without becoming a risk 

to private property and human health, 

and they cannot be detonated in the 

dark. If a marine mammal enters the 

blast area following the emplacement of 

charges, detonation will be delayed as 

long as possible. All other legal 

measures to avoid injury will be 

utilized; however, the charges will be 

detonated when delay is no longer 

feasible. As discussed in the mitigation 

section, in order to minimize the 

chances the charges need to be 

detonated while animals are present in 

the vicinity, the IHA includes a 

mitigation measure requiring explosives 

to be set as early in the day as possible, 

and detonated as soon as the preclearance zone is clear for 30 minutes. 

Sounds resulting from confined 

blasting may result in the incidental 

take of marine mammals by Level A and 

Level B harassment in the form of slight 

injury (auditory and non-auditory) and 

behavioral harassment. Dredging and 

disposal of dredged material are not 

expected to result in either Level A or 

Level B harassment due to the low 

source level and mid-channel location 

of the dredging activities. If dredging is 

sufficient to deepen the channel to the 

required depth, reduced or no blasting 

may be necessary. The notice for the 

proposed IHA (88 FR 21630, April 11, 

2023) analyzed a conservative scenario 

requiring blasting approximately 50 

percent of the bar area, resulting in 


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approximately 1,800 drilled boreholes 

and up to 24 total blasting events. 

A detailed description of the planned 

project is provided in the Federal 

Register notice for the proposed IHA (88 

FR 21630, April 11, 2023). Since that 

time, no changes have been made to the 

planned activities. Therefore, a detailed 

description is not provided here. Please 

refer to that Federal Register notice for 

the detailed description of the specific 

activity. 

Comments and Responses 

A notice of NMFS’ proposal to issue 

an IHA to the USACE was published in 

the Federal Register on April 11, 2023 

(88 FR 21630). That notice described, in 

detail, USACE’s planned activities, the 

marine mammal species that may be 

affected by the activities, and the 

anticipated effects on marine mammals. 

In that notice, we requested public 

input on the request for authorization 

described therein, our analyses, the 

proposed authorization, and any other 

aspect of the notice of proposed IHA, 

and requested that interested persons 

submit relevant information, 

suggestions, and comments. This 

proposed notice was available for a 30- 

day public comment period. 

NMFS received two non-substantive 

comments on the proposed IHA: one 

from the U.S. Geological Survey stating 

no objections to the project, and one 

from a private citizen opposed to 

offshore wind, which is not related to 

this action. 

Changes From the Proposed IHA to 

Final IHA 

Since the Federal Register notice of 

the proposed IHA was published (88 FR 

21630, April 11, 2023), NMFS published 

the final 2022 Alaska and Pacific Stock 

Assessment Reports (SARs), which 

describe revised stock structures under 

the MMPA for humpback whales. 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 1), 

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). 

Additionally, between the publication 

of the proposed IHA (88 FR 21630, April 

11, 2023) and this notice, the USACE 

requested that the effective dates of the 

authorization be shifted from November 

1, 2023 through October 31, 2024 to 

January 1, 2024 through December 31, 

2024 due to logistical constraints. The 

analysis presented in the proposed IHA 

remains valid because the estimated 

takes were based on year-round 

monitoring data at the project location. 

The change to the effective dates of the 

authorization is reflected in the DATES

section, above. 

Description of Marine Mammals in the 

Area of Specified Activities 

Sections 3 and 4 of the application 

summarize available information 

regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history of the potentially 

affected species. NMFS fully considered 

all of this information, and we refer the 

reader to these descriptions, 

incorporated here by reference, instead 

of reprinting the information. 

Additional information regarding 

population trends and threats may be 

found in NMFS’ Stock Assessment 

Reports (SARs; www.fisheries.noaa.gov/ 

national/marine-mammal-protection/ 

marine-mammal-stock-assessments) 

and more general information about 

these species (e.g., physical and 

behavioral descriptions) may be found 

on NMFS’ website (https://

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

Table 1 lists all species or stocks for 

which take is expected and 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’ U.S. Alaska and Pacific Ocean 

SARs. All values presented in table 1 

are the most recent available at the time 

of publication and are available online 

at: www.fisheries.noaa.gov/national/

marine-mammal-protection/marinemammal-stock-assessments. 

TABLE 1—SPECIES LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES 1

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 2

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 3

PBR Annual 

M/SI 4

Order Artiodactyla—Infraorder Cetacea—Mysticeti (baleen whales) 

Family Balaenopteridae 

(rorquals): 

Humpback Whale 5 ............... Megaptera novaeangliae ............ Hawai1i ........................................

Mexico—North Pacific ................

Western North Pacific .................

-, -, N 

T, D, Y 

E, D, Y 

11,278 (0.56, 7,265, 2020) ...

918 (0.217, UNK, 2006) .......

1,084 (0.088, 1,007, 2021) ...

127 

UND 

3.4 

27.09 

0.57 

5.82 

Odontoceti (toothed whales, dolphins, and porpoises) 

Family Phocoenidae (porpoises): 

Harbor porpoise .................... Phocoena phocoena ................... Bering Sea 5 ................................

Gulf of Alaska .............................

-, -, Y 

-, -, Y 

UNK (UNK, N/A, 2008) ........

31,046 (0.21, N/A, 1998) ......

UND 

UND 

0.4 

72 


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TABLE 1—SPECIES LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES 1—Continued 

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 2

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 3

PBR Annual 

M/SI 4

Order Carnivora—Pinnipedia 

Family Otariidae (eared seals and 

sea lions): 

Steller Sea Lion .................... Eumetopias jubatus .................... Western .......................................

Eastern ........................................

E, D, Y 

-, -, N 

52,932 (N/A, 52,932, 2019) ..

43,201 (N/A, 43,201, 2017) ..

318 

2592 

254 

112 

Family Phocidae (earless seals): 

Harbor Seal .......................... Phoca vitulina ............................. Aleutian Islands .......................... -, -, N 5,588 (N/A, 5,366, 2018) ...... 97 90 

1 Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy’s Committee on Taxonomy 

(https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)). 2Endangered 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. 3 NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of stock 

abundance. In some cases, CV is not applicable due to lack of recent surveys allowing for accurate assessment of stock abundance. 4These 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. 5The best available abundance estimate and Nmin are likely an underestimate for the entire stock because it is based upon a survey that covered only a small portion of the stock’s range. PBR for this stock is undetermined due to this estimate being older than 8 years. 

A detailed description of the of the 

species likely to be affected by the 

Unalaska Channel Deepening 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 

21630, April 11, 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. Please refer to that 

Federal Register notice for these 

descriptions. Please also refer to NMFS’ 

website (https://www.fisheries.

noaa.gov/find-species) 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 

associated hearing ranges are provided 

in table 2. 

TABLE 2—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 et al., 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 

USACE’s construction activities have 

the potential to result in behavioral 

harassment of marine mammals in the 

vicinity of the blasting area. The notice 


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of proposed IHA (88 FR 21630, April 11, 

2023) included a discussion of the 

effects of anthropogenic noise on marine 

mammals and the potential effects of 

underwater noise from confined blasting 

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 

proposed IHA (88 FR 21630, April 11, 

2023). 

Estimated Take of Marine Mammals 

This section provides an estimate of 

the number of incidental takes 

authorized through this IHA, which 

informs 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 

explosive source (i.e., confined blasting) 

has the potential to result in disruption 

of behavioral patterns for individual 

marine mammals. There is also some 

potential for auditory injury and tissue 

damage (Level A harassment) to result, 

primarily for cetaceans (humpback 

whale and harbor porpoise) and phocids 

because predicted auditory injury zones 

are larger than for otariids. 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. While 

blasting has the potential to result in 

mortality, when the isopleths within 

which mortality could occur were 

calculated, the zones were sufficiently 

small that the risk of mortality is 

considered discountable. Below we 

describe how the take numbers were 

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 PTS of some 

degree (equated to Level A harassment). 

Thresholds have also been developed to 

identify the pressure levels above which 

animals may incur different types of 

tissue damage (non-acoustic Level A 

harassment or mortality) from exposure 

to pressure waves from explosive 

detonation. 

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 (including 

explosives) or non-impulsive). These 

thresholds are provided in table 3, 

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/marinemammal-acoustic-technical-guidance. 

Explosive sources—Based on the best 

available science, NMFS uses the 

acoustic and pressure thresholds 

indicated in tables 3 and 4 to predict the 

onset of behavioral harassment, PTS, 

TTS, tissue damage, and mortality. 

For explosive activities using single 

detonations (i.e., no more than one 

detonation within a day), such as those 

described in the planned activity, NMFS 

uses TTS onset thresholds to assess the 

likelihood of behavioral harassment, 

rather than the Level B Harassment 

threshold for multiple detonations 

indicated in table 3. While marine 

mammals may also respond 

behaviorally to single explosive 

detonations, these responses are 

expected to typically be in the form of 

a startle reaction, rather than a more 

meaningful disruption of a behavioral 

pattern. On the rare occasion that a 

single detonation might result in a 

behavioral disturbance that qualifies as 

Level B harassment, it would be 

expected to be in response to a 

comparatively higher received level. 

Accordingly, NMFS considers the 

potential for these responses to be 

quantitatively accounted for through the 

application of the TTS threshold, 

which, as noted above, is 5 dB higher 

than the behavioral harassment 

threshold for multiple explosives. 

TABLE 3—EXPLOSIVE THRESHOLDS FOR MARINE MAMMALS FOR PTS, TTS, AND BEHAVIOR

[Multiple detonations] 

Hearing group PTS impulsive 

thresholds 

TTS impulsive 

thresholds 

Behavioral threshold 

(multiple detonations) 

Low-Frequency (LF) Cetaceans ....... Cell 1: Lp,0-pk,flat: 219 dB; LE,LF,24h: 

183 dB.

Cell 2: Lp,0-pk,flat: 213 dB; LE,LF,24h: 

168 dB.

Cell 3: LE,LF,24h: 163 dB. 

Mid-Frequency (MF) Cetaceans ....... Cell 4: Lp,0-pk,flat: 230 dB; LE,MF,24h: 

185 dB.

Cell 5: Lp,0-pk,flat: 224 dB; LE,MF,24h: 

170 dB.

Cell 6: LE,MF,24h: 165 dB. 

High-Frequency (HF) Cetaceans ...... Cell 7: Lp,0-pk,flat: 202 dB; LE,HF,24h: 

155 dB.

Cell 8: Lp,0-pk,flat: 196 dB; LE,HF,24h: 

140 dB.

Cell 9: LE,HF,24h: 135 dB. 

Phocid Pinnipeds (PW) (Underwater) Cell 10: Lp,0-pk,flat: 218 dB; 

LE,PW,24h: 185 dB.

Cell 11: Lp,0-pk,flat: 212 dB; 

LE,PW,24h: 170 dB.

Cell 12: LE,PW,24h: 165 dB. 


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TABLE 3—EXPLOSIVE THRESHOLDS FOR MARINE MAMMALS FOR PTS, TTS, AND BEHAVIOR—Continued 

[Multiple detonations] 

Hearing group PTS impulsive 

thresholds 

TTS impulsive 

thresholds 

Behavioral threshold 

(multiple detonations) 

Otariid Pinnipeds (OW) (Underwater) Cell 13: Lp,0-pk,flat: 232 dB; 

LE,OW,24h: 203 dB.

Cell 14: Lp,0-pk,flat: 226 dB; 

LE,OW,24h: 188 dB.

Cell 15: LE,OW,24h: 183 dB. 

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS/TTS onset. 

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, 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 overall marine mammal 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. 

TABLE 4—LUNG AND GI TRACT INJURY THRESHOLDS FOR UNDERWATER EXPLOSIVES

Hearing group Mortality 

(severe lung injury) * Slight lung injury * GI tract injury 

All Marine Mammals ...................... Cell 1: Modified Goertner model; 

Equation 1.

Cell 2: Modified Goertner model; 

Equation 2.

Cell 3: Lp,0-pk,flat: 237 dB. 

* Lung injury (severe and slight) thresholds are dependent on animal mass (Recommendation: table C.9 from DON 2017 based on adult and/or 

calf/pup mass by species). 

Note: Peak sound pressure (Lpk) has a reference value of 1 μPa. In this table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, 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 overall marine mammal generalized hearing range. 

Modified Goertner Equations for severe and slight lung injury (pascal-second). 

Equation 1: 103M1/3(1 + D/10.1)1/6 Pa-s. 

Equation 2: 47.5M1/3(1 + D/10.1)1/6 Pa-s. 

M animal (adult and/or calf/pup) mass (kg) (table C.9 in DoN 2017). 

D animal depth (meters). 

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. 

NMFS computed cumulative sound 

exposure impact zones from the blasting 

information provided by the USACE. 

Peak source levels of the confined blasts 

were calculated based on Hempen et al. 

(2007), and scaled using a distance of 10 

ft (3 m) and a weight of 95 lbs (43.1 kg) 

for a single charge. The total charge 

weight is defined as the product of the 

single charge weight and the number of 

charges. In this case, the number of 

charges is 75. Explosive energy was then 

computed from peak pressure of the 

single maximum charge, using the 

pressure and time relationship of a 

shock wave (Urick, 1983). Due to time 

and spatial separation of each single 

charge by a distance of 10 ft (3m), the 

accumulation of acoustic energy is 

added sequentially, assuming the 

transmission loss follows cylindrical 

spreading within the matrix of charges. 

The sound exposure level (SEL) from 

each charge at its source can then be 

calculated, followed by the received 

SEL from each charge. Since the charges 

will be deployed in a grid of 10 ft (3 m) 

by 10 ft (3 m) apart, the received SELs 

from different charges to a given point 

will vary depending on the distance of 

the charges from the receiver. Without 

specific information regarding the 

layout of the charges, the modeling 

assumes a grid of 8 by 9 charges with 

an additional three charges located in 

three peripheral locations. Among the 

various total SELs calculated (one at a 

receiver location corresponding to each 

perimeter charge), the largest value, 

SELtotal (max) is selected to calculate 

the impact range. Using the pressure 

versus time relationship above, the 

frequency spectrum of the explosion can 

be computed by taking the Fourier 

transform of the pressure (Weston, 

1960), and subsequently be used to 

produce hearing range weighted 

metrics. 

Frequency specific transmission loss 

of acoustic energy due to absorption is 

computed using the absorption 

coefficient, a (dB/km), summarized by 

Franc ̧ois and Garrison (1982a, b). 

Seawater properties for computing 

sound speed and absorption coefficient 

were based on NMFS Alaska Fisheries 

Science Center report of mean 

measurements in Auke Bay (Sturdevant 

and Landingham, 1993) and the 2022 

average seawater temperature from 

Unalaska (NOAA, 2023). Transmission 

loss was calculated using the sonar 

equation: 

TL = SELtotal(m)¥SELthreshold

where SELthreshold is the Level A 

harassment threshold. The distances, R, 

where such transmission loss is 

achieved were computed numerically 

by combining both geometric 

transmission loss, and transmission loss 

due to frequency-specific absorption. A 

spreading coefficient of 20 is assumed to 

account for acoustic energy loss from 

the sediment into the water column. 

The outputs from this model are 

summarized in table 5, below. 


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TABLE 5—MODEL RESULTS OF IMPACT ZONES FOR BLASTING IN METERS (m) 

Species Mortality Slight lung 

injury GI tract PTS: SELcum PTS: SPLpk TTS: SELcum TTS: SPLpk 

Low frequency cetacean .......................... 4.0 9.2 25.8 * 344.66 205.29 * 1,918 409.62 

High frequency cetacean ......................... 20.3 47.5 25.8 1,213.79 * 1,453.37 * 4,435.57 2,899.86 

Otariid ....................................................... 13.8 32.3 25.8 40.00 * 91.92 * 249.76 183.40 

Phocid ...................................................... 18.2 42.5 25.8 164.84 * 230.34 * 909.10 459.60 

* For the dual criteria of SELcum and SPLpk, the largest of the two calculated distances for each species group was used in our analysis. The 

PTS and TTS distances for Steller sea lions resulting from the model seemed uncharacteristically small when compared to the other thresholds 

resulting from the model and were doubled to 92 m and 230 m respectively for take estimation, mitigation, and monitoring. 

Marine Mammal Occurrence 

In this section, we provide 

information about the occurrence of 

marine mammals, including density or 

other relevant information that informed 

the take calculations. Reliable densities 

are not available for Iliuliuk Bay, and 

generalized densities for the North 

Pacific are not applicable given the high 

variability in occurrence and density at 

specific areas around the Aleutian 

Island chain. Therefore, the USACE 

consulted previous survey data in and 

around Iliuliuk Bay and Dutch Harbor to 

arrive at a number of animals expected 

to occur within the project area per day. 

Figure 4–8 and table 4–3 in the IHA 

application provide further detail on 

observations of humpback whales, 

Steller sea lions, and harbor seals in and 

around Iliuliuk Bay. Harbor porpoise 

were not addressed in the IHA 

application; however, NMFS has 

authorized takes of harbor porpoise take 

out of an abundance of caution, based 

on the 2017 sighting of porpoises in the 

action area by USACE biologists. 

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. 

Since reliable densities are not 

available, the USACE requested take 

based on the maximum number of 

animals that may occur in the blasting 

area per day multiplied by the number 

of days of the activity. The applicant 

varied these calculations based on 

certain factors. Because of the nature of 

the planned blasting (i.e., no more than 

one blasting event per day), the 

behavioral thresholds associated with 

the activity are the same as for the onset 

of TTS for all species. Both behavioral 

disturbance and TTS may occur. 

Humpback whale—Humpback whales 

are commonly sighted outside the 

mouth of Iliuliuk Bay, and were most 

common in August and September 

between 2 and 8 km from the survey site 

outside the mouth of the bay. 

Humpbacks were also spotted within 

Iliuliuk Bay in much lower numbers 

(maximum daily sightings within the 

bay: 4; outside the bay: 47) (USACE 

2022). Based on the previous monitoring 

efforts in and around Iliuliuk Bay, 

USACE and NMFS estimated that a 

maximum of two animals may be 

present within the Level B harassment 

threshold for each blasting event. While 

NMFS expects that the monitoring and 

mitigation described later in this 

document will be effective at preventing 

injurious take of marine mammals, we 

recognize that humpback whales are 

common in the area, that animals may 

enter the blasting area after charges have 

been set, and that there is a limit on the 

amount of time detonation may be 

safely delayed. Humpback whales are 

highly visible, and their presence would 

likely be known before charges are laid 

on a blasting day. We therefore 

conservatively estimate up to 10 percent 

of the blasting events may include a 

humpback whale within the Level A 

harassment isopleth. With a maximum 

take of 2 animals per day, multiplied by 

a maximum of 24 days of blasting, we 

have authorized up to 48 takes by Level 

B harassment and up to 3 takes by Level 

A harassment of humpback whales. 

Harbor porpoise—Harbor porpoise 

were not included in the IHA 

application. This species typically 

travels alone or in pairs, but may 

occasionally be sighted in larger groups. 

Based on the USACE’s observation of a 

group of eight individuals in the project 

area in 2017, and other infrequent 

sightings of harbor porpoise in and 

around Iliulliuk Bay, NMFS 

conservatively estimated that two 

animals may occur within the Level B 

harassment threshold on up to 25 

percent of blasting days. Out of an 

abundance of caution, and because this 

species is both very sensitive to noise 

(meaning the Level A harassment zone 

is comparatively larger), including 

explosions (von Benda-Beckmann et al., 

2015), and difficult to see in the field, 

NMFS also proposed that up to two 

harbor porpoise could be within the 

Level A harassment threshold for up to 

10 percent of the blasting events. Given 

24 days of blasting, we have authorized 

up to 12 harbor porpoise takes by Level 

B harassment, and up to 5 harbor 

porpoise takes by Level A harassment 

over the course of the activity. 

Steller sea lion—During previous 

monitoring efforts, Steller sea lions were 

sighted most frequently inside of 

Iliuliuk Bay, within 4 km of the project 

area. The maximum number of sightings 

in a single day was 32, though it is 

unclear whether this includes multiple 

sightings of the same large group of 10 

to 12 individuals (USACE 2022). Steller 

sea lions in this area are known to 

congregate around and follow fishing 

vessels that regularly transit into and 

out of Dutch Harbor. Given the previous 

monitoring data, USACE and NMFS 

conservatively estimated that a 

maximum of two animals may be within 

the Level B harassment threshold for 

each blast. While NMFS expects that the 

monitoring and mitigation described 

later in this document will be effective 

at preventing injurious take of marine 

mammals, we recognize that Steller sea 

lions are common in the area, that 

animals may enter the blasting area after 

charges have been set, and that there is 

a limit on the amount of time detonation 

may be safely delayed. Steller sea lions 

may be difficult for observers to detect 

before charges are laid on a blasting day, 

and we therefore conservatively 

estimated up to two Steller sea lions 

may be within the Level A harassment 

isopleth for up to 20 percent of the 

blasting events. With a maximum take 

of 2 animals per day, multiplied by a 

maximum of 24 days of blasting, we 

have authorized up to 48 takes by Level 

B harassment and up to 5 takes by Level 

A harassment of Steller sea lions. 

Harbor seal—Previous monitoring 

efforts documented harbor seals close to 

the shoreline Ulatka Head, on the 

northeastern side of Iliuliuk Bay 

between 1 and 4 km from the project 

area, but they were sighted throughout 

Iliuliuk Bay in all survey months 

(April–October) (USACE 2022). They 

were most frequently sighted in the 

summer months, with up to 43 sightings 

on a single day. Based on the high rate 

of sightings within a few hundred 


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meters of the Level B harassment 

isopleth in the previous data, USACE 

and NMFS conservatively assumed a 

maximum of 10 seals within the Level 

B harassment threshold for each blast. 

While NMFS expects that the 

monitoring and mitigation described 

later in this document will be effective 

at preventing injurious take of marine 

mammals, we recognize that harbor 

seals are common in the area, that 

animals may enter the blasting area after 

charges have been set, and that there is 

a limit on the amount of time detonation 

may be safely delayed. Harbor seals 

were frequently sighted close to the 

Level B threshold distance and may be 

difficult for observers to detect before 

charges are laid on a blasting day. We 

therefore conservatively estimated up to 

two harbor seals may be within the 

Level A harassment isopleth for up to 20 

percent of the blasting events. With a 

maximum take of 10 animals per day, 

multiplied by a maximum of 24 days of 

blasting, we have authorized up to 240 

takes by Level B harassment and up to 

5 takes by Level A harassment of harbor 

seals. 

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. 

In addition to the measures described 

later in this section, the USACE will 

employ the following standard 

mitigation measures: 

• Conduct a briefing between 

construction supervisors and crews and 

the marine mammal monitoring team 

prior to the start of construction, and 

when new personnel join the work, to 

explain responsibilities, communication 

procedures, marine mammal monitoring 

protocol, and operational procedures; 

• For in-water and over-water heavy 

machinery work, if a marine mammal 

comes within 10 m, operations must 

cease and vessels must reduce speed to 

the minimum level required to maintain 

steerage and safe working conditions; 

• Work may only occur during 

daylight hours, when visual monitoring 

of marine mammals can be conducted; 

and 

• If take reaches the authorized limit 

for an authorized species, the blasting 

activity will be stopped as these species 

approach the Monitoring zones (table 6) 

to avoid additional take of them. 

TABLE 6—MONITORING AND PRE-CLEARANCE ZONES FOR BLASTING ACTIVITIES FOR SPECIES WITH AUTHORIZED TAKE

Pre-clearance zones (m) 

Monitoring zones 

(m) 

Level A 

harassment 

thresholds 

(PTS) 

Level B 

harassment 

thresholds 

(TTS) 

Humpback whale ......................................................................................................................... 345 1,918 2,500 

Harbor Porpoise ........................................................................................................................... 1,214 4,500 5,000 

Steller sea lion ............................................................................................................................. 92 250 2,500 

Harbor seal .................................................................................................................................. 231 910 2,500 

The USACE will implement the 

following mitigation requirements: 

Establishment of Pre-clearance and 

Monitoring Zones—The USACE and 

NMFS have identified pre-clearance 

zones associated with the distances 

within which Level A harassment and 

Level B harassment are expected to 

occur. Additionally, monitoring zones 

that extend beyond the pre-clearance 

zones have been established. Monitoring 

zones provide utility for observing by 

establishing monitoring protocols for 

areas adjacent to the pre-clearance 

zones. Monitoring zones enable 

observers to be aware of and 

communicate the presence of marine 

mammals in the project area outside the 

Level B harassment pre-clearance zone 

and thus prepare for a potential 

cessation of activity should the animal 

enter the Level A harassment zone (table 

6). 

Pre-monitoring and Delay of 

Activities—Prior to the start of daily inwater activity, or whenever a break in 

activity of 30 minutes or longer occurs, 

the observers will observe the preclearance and monitoring zones for a 

period of 30 minutes. Pre-clearance 

zones will be considered cleared when 

a marine mammal has not been 

observed within the zone for that 30- 

minute period. If any marine mammal is 

observed within the Level A preclearance zone, activity cannot proceed 

until the animal has left the zone or has 

not been observed for 15 minutes. If 

marine mammals are observed within 

the Level B pre-clearance or monitoring 

zones but outside of the Level A preclearance zones, work may proceed in 

good visibility conditions. If work 

ceases for more than 30 minutes, the 

pre-activity monitoring of both the 

monitoring zones and pre-clearance 

zones will commence. 

In the event that a large whale for 

which take is not authorized is sighted 

within either the monitoring or the 

Level A or Level B pre-clearance zones 

during monitoring prior to placement of 

charges on a planned blast day, USACE 

will evaluate whether environmental 


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conditions allow for blasting to be 

delayed to the following day. If charges 

have already been laid before the whale 

is sighted, blasting will not commence 

until the whale has been positively 

observed outside of the monitoring 

zone, subject to the safety restrictions 

discussed below. 

Charges for blasting will not be laid if 

marine mammals are within the Level A 

pre-clearance zone or appear likely to 

enter the Level A pre-clearance zone. 

However, once charges are placed, they 

cannot be safely left undetonated for 

more than 24 hours. For blasting, the 

monitoring and pre-clearance zones will 

be monitored for a minimum of 30 

minutes prior to detonating the blasts. If 

a marine mammal is sighted within the 

Level A or Level B pre-clearance zones 

following the emplacement of charges, 

detonation will be delayed until the 

zones are clear of marine mammals for 

30 minutes. This will continue as long 

as practicable within the constraints of 

the blasting design but not beyond 

sunset on the same day as the charges 

cannot lay dormant for more than 24 

hours, which may force the detonation 

of the blast in the presence of marine 

mammals. All other legal measures to 

avoid injury will be utilized; however, 

the charges will be detonated when 

delay is no longer feasible. 

Charges will be laid as early as 

possible in the morning and stemming 

procedures will be used to fill the 

blasting holes to potentially reduce the 

noise from the blasts. Blasting will only 

be planned to occur in good visibility 

conditions, and at least 30 minutes after 

sunrise and at least one hour prior to 

sunset. The zones will also be 

monitored for 1 hour post-blasting. 

If a detonation occurs when a marine 

mammal is known to be within the 

Level A or Level B pre-clearance zones, 

USACE will observe the blast area for 

two hours after the blasting event, or 

until visibility or safety conditions 

decline to the point that monitoring is 

no longer feasible, to determine as much 

as possible about the behavior and 

physical status of the marine mammal 

affected by the blasting event. 

Based on our evaluation of the 

applicant’s planned measures, as well as 

other measures considered by NMFS, 

NMFS has determined that the listed 

mitigation measures provide the means 

of effecting the least practicable impact 

on the affected species or stocks and 

their habitat, paying particular attention 

to rookeries, mating grounds, and areas 

of similar significance, and on the 

availability of such species or stock for 

subsistence uses. 

Monitoring and Reporting 

In order to issue an IHA for an 

activity, section 101(a)(5)(D) of the 

MMPA states that NMFS must set forth 

requirements pertaining to the 

monitoring and reporting of such taking. 

The MMPA implementing regulations at 

50 CFR 216.104(a)(13) indicate that 

requests for authorizations must include 

the suggested means of accomplishing 

the necessary monitoring and reporting 

that will result in increased knowledge 

of the species and of the level of taking 

or impacts on populations of marine 

mammals that are expected to be 

present while conducting the activities. 

Effective reporting is critical both to 

compliance as well as ensuring that the 

most value is obtained from the required 

monitoring. 

Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density); 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) action or 

environment (e.g., source 

characterization, propagation, ambient 

noise); (2) affected species (e.g., life 

history, dive patterns); (3) co-occurrence 

of marine mammal species with the 

activity; or (4) biological or behavioral 

context of exposure (e.g., age, calving or 

feeding areas); 

• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors; 

• How anticipated responses to 

stressors impact either: (1) long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks; 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat); and, 

• Mitigation and monitoring 

effectiveness. 

Visual Monitoring 

Monitoring will be conducted 30 

minutes before, during, and 30 minutes 

after construction activities. In addition, 

observers must record all incidents of 

marine mammal occurrence, regardless 

of distance from activity, and must 

document any behavioral reactions in 

concert with distance from construction 

activities. 

Protected Species Observers (PSOs) 

will be land- and boat-based. For 

blasting, three PSOs will be required 

(two land-based and one boat-based). 

Observers will be stationed at locations 

that provide adequate visual coverage 

for shutdown and monitoring zones. 

Potential observation locations are 

depicted in Figure 3–1 of the applicant’s 

Marine Mammal Monitoring and 

Mitigation Plan. During blasting, preblast monitoring, and post-blast 

monitoring, three observers will be on 

duty. Optimal observation locations will 

be selected based on visibility and the 

type of work occurring. All PSOs will be 

trained in marine mammal 

identification and behaviors and are 

required to have no other project-related 

tasks while conducting monitoring. In 

addition, monitoring will be conducted 

by qualified observers, who will be 

placed at the best vantage point(s) 

practicable to monitor for marine 

mammals and implement shutdown/ 

delay procedures when applicable. 

Monitoring of construction activities 

must be conducted by qualified PSOs 

(see below), who must have no other 

assigned tasks during monitoring 

periods. The applicant must adhere to 

the following conditions when selecting 

observers: 

• Independent PSOs must be used 

(i.e., not construction personnel); 

• At least one PSO must have prior 

experience working as a marine 

mammal observer during construction 

activities; 

• Other PSOs may substitute 

education (degree in biological science 

or related field) or training for 

experience; 

• Where a team of three or more PSOs 

are required, a lead observer or 

monitoring coordinator must be 

designated. The lead observer must have 

prior experience working as a marine 

mammal observer during construction; 

and 

• The applicant must submit PSO 

curriculum vitaes for approval by 

NMFS. 

The applicant must ensure that 

observers 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 


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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. 

At least 24 hours prior to blasting, the 

USACE will notify the Office of 

Protected Resources, NMFS Alaska 

Regional Office, and the Alaska 

Regional Stranding Coordinator that 

blasting is planned to occur, as well as 

notify these parties within 24 hours 

after blasting that blasting actually 

occurred. If a marine mammals is 

known to be within the Level A or Level 

B pre-clearance zones during a 

detonation, USACE will report the 

following information within 24 hours 

of the blasting event: 

• Description of the blasting event; 

• PSO positions and monitoring effort 

for the 24 hours preceding the blast; 

• Environmental conditions (e.g., 

Beaufort sea state, visibility); 

• Description of all marine mammal 

observations in the 24 hours preceding 

the incident; 

• Species identification or 

description of the animal(s) involved; 

• Fate of the animal(s); and 

• Photographs or video footage of the 

animal(s) (if equipment is available). 

A draft marine mammal monitoring 

report will be submitted to NMFS 

within 90 days after the completion of 

construction activities. It will include 

an overall description of work 

completed, a narrative regarding marine 

mammal sightings, and associated PSO 

data sheets. Specifically, the report must 

include: 

• Date and time that monitored 

activity begins or ends; 

• Construction activities occurring 

during each observation period; 

• Weather parameters (e.g., percent 

cover, visibility); 

• Water conditions (e.g., sea state, 

tide state); 

• Species, numbers, and, if possible, 

sex and age class of marine mammals; 

• Description of any observable 

marine mammal behavior patterns, 

including bearing and direction of travel 

and distance from construction activity; 

• Distance from construction 

activities to marine mammals and 

distance from the marine mammals to 

the observation point; 

• Locations of all marine mammal 

observations; and 

• Other human activity in the area. 

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. 

In the unanticipated event that the 

specified activity likely causes the take 

of a marine mammal in a manner 

prohibited by the IHA (if issued), such 

as a serious injury or mortality, the 

USACE will immediately cease the 

specified activities and report the 

incident to the Office of Protected 

Resources, NMFS Alaska Regional 

Office, and the Alaska Regional 

Stranding Coordinator. The report will 

include the following information: 

• Description of the incident; 

• Environmental conditions (e.g., 

Beaufort sea state, visibility); 

• Description of all marine mammal 

observations in the 24 hours preceding 

the incident; 

• Species identification or 

description of the animal(s) involved; 

• Fate of the animal(s); and 

• Photographs or video footage of the 

animal(s) (if equipment is available). 

Activities will not resume until NMFS 

is able to review the circumstances of 

the prohibited take. NMFS will work 

with the USACE to determine what is 

necessary to minimize the likelihood of 

further prohibited take and ensure 

MMPA compliance. The USACE will 

not be able to resume their activities 

until notified by NMFS via letter, email, 

or telephone. 

In the event that the USACE discovers 

an injured or dead marine mammal, and 

the lead PSO determines that the cause 

of the injury or death is unknown and 

the death is relatively recent (e.g., in 

less than a moderate state of 

decomposition as described in the next 

paragraph), the USACE will 

immediately report the incident to the 

Office of Protected Resources, NMFS 

Alaska Regional Office, and the Alaska 

Regional Stranding Coordinator. The 

report will include the same 

information identified in the paragraph 

above. Activities will be able to 

continue while NMFS reviews the 

circumstances of the incident. NMFS 

will work with the USACE to determine 

whether modifications in the activities 

are appropriate. 

In the event that the USACE discovers 

an injured or dead marine mammal and 

the lead PSO determines that the injury 

or death is not associated with or related 

to the activities authorized in the IHA 

(e.g., previously wounded animal, 

carcass with moderate to advanced 

decomposition, or scavenger damage), 

the USACE will report the incident to 

the Office of Protected Resources, NMFS 

Alaska Regional Office, and the NMFS 

Alaska Stranding Hotline and/or by 

email to the Alaska Regional Stranding 

Coordinator, within 24 hours of the 

discovery. The USACE will provide 

photographs, video footage (if available), 

or other documentation of the stranded 

animal sighting to NMFS and the 

Marine Mammal Stranding Coordinator. 

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, the discussion of 

our analysis applies to all the species 

listed in table 1, given that the 

anticipated effects of this activity on 

these different marine mammal stocks 

are expected to be similar. There is little 

information about the nature or severity 

of the impacts, or the size, status, or 

structure of any of these species or 


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Federal Register / Vol. 88, No. 225 / Friday, November 24, 2023 / Notices 82335 

stocks that would lead to a different 

analysis for this activity. 

As stated in the mitigation section, 

pre-clearance zones equal to or 

exceeding Level A isopleths shown in 

table 6 for blasting will be implemented 

for all species. Serious injury or 

mortality is not anticipated nor 

authorized. 

Behavioral disturbances of marine 

mammals to blasting, if any, are 

expected to be mild and temporary due 

to the short-term duration of the noise 

produced by the source and the fact that 

only a single blasting event will occur 

on a given day. Additionally, blasting 

events will not occur on consecutive 

days. Given the short duration of noisegenerating activities per day and that 

blasting events would occur on a 

maximum of 24 days, any harassment 

would be temporary. For all species 

except humpbacks, there are no known 

biologically important areas near the 

project zone that will be impacted by 

the construction activities. The project 

area occupies a small percentage of the 

humpback whale feeding BIA and 

Critical Habitat areas, and there is 

sufficient similar habitat nearby. 

Acoustic impacts will be short-term and 

temporary in duration. The region of 

Iliuliuk Bay where the project will take 

place is located in a highly trafficked 

commercial port area with regular 

marine vessel traffic. 

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 any of the 

species or stocks through effects on 

annual rates of recruitment or survival: 

• No serious injury or mortality is 

anticipated or authorized; 

• Authorized Level A harassment will 

be very small amounts and of low 

degree; 

• The intensity of anticipated takes 

by Level B harassment is relatively low 

for all stocks. Level B harassment will 

be primarily in the form of behavioral 

disturbance, resulting in avoidance of 

the project areas around where blasting 

is occurring, with some TTS that may 

limit the detection of acoustic cues for 

relatively brief amounts of time; 

• While a feeding BIA and Critical 

Habitat for humpback whales exist in 

the action area, the planned activity 

occupies a small percentage of the total 

BIA and of the Critical Habitat, and 

would occur on a short term, temporary 

basis. 

• The USACE will implement 

mitigation measures, such as preclearance zones, for all in-water and 

over-water activities; and 

• Monitoring reports from similar 

work in Alaska have documented little 

to no effect on individuals of the same 

species impacted by the specified 

activities (USACE, 2020). 

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 planned 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. 

Table 7 presents the number of 

animals that could be exposed to 

received noise levels that may result in 

take by Level A or Level B harassment 

for the construction at Iliuliuk Bay, 

Unalaska. Our analysis shows that less 

than one-third of the best available 

population estimate of each affected 

stock could be taken. Therefore, the 

numbers of animals authorized to be 

taken for all species would be 

considered small relative to the relevant 

stocks or populations even if each 

estimated taking occurred to a new 

individual—an extremely unlikely 

scenario. For harbor seals and Steller 

sea lions occurring in the vicinity of the 

project site, there will almost certainly 

be some overlap in individuals present 

day-to-day, and these takes are likely to 

occur only within some small portion of 

the overall regional stock. 

TABLE 7—SUMMARY OF AUTHORIZED INSTANCES OF LEVEL A AND LEVEL B HARASSMENT

Species DPS/stock 

Number of 

takes by 

Level B 

harassment 

by stock 

Number of 

takes by 

Level A 

harassment 

by stock 

Stock 

abundance 

Percent of 

population 

Humpback whale ...................................... Western North Pacific .............................. 0.96 0 1,107 0.1 

Mexico—North Pacific .............................. 3.36 0 4,973 0.1 

Hawaii ....................................................... 43.68 3 10,103 0.5 

Harbor seal ............................................... Aleutian Island Stock ................................ 240 5 5,588 4.4 

Harbor porpoise 1 ...................................... Bering Sea ................................................ 12 5 31,046 0.05 

Gulf of Alaska ........................................... .................... .................... .................... ....................

Steller sea lion .......................................... Western DPS ............................................ 48 5 52,932 0.1 

1There is not enough information available to determine takes for separate stocks for harbor porpoise. Calculations have been based on the 

best available stock abundance for the Gulf of Alaska stock, as there are no available data for the Bering Sea stock. This number is conservative, because it represents a minimum value of both stocks. 

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’’ 


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82336 Federal Register / Vol. 88, No. 225 / Friday, November 24, 2023 / Notices 

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. 

Subsistence activities in Unalaska 

have historically included the harvest of 

pinnipeds and sea otters. However, 

subsistence harvests of marine 

mammals declined between 1994 and 

2008 (the last year for which data are 

available) (ADF&G 2022). Additionally, 

a ban on firearm discharge within the 

city limits of the City of Unalaska means 

that current subsistence harvesting 

typically occurs from skiffs in areas 

outside of Dutch Harbor and Iliuliuk 

Bay, including Wide Bay, Kalekta Bay, 

Bishop Point, Wislow Island, and 

Beaver Inlet. The planned activity 

would not impact these areas. 

Any impacts to marine mammals from 

the planned activity are likely to be 

short-term and temporary, and limited 

to the area around the blasting site. 

While a limited number of individuals 

may experience PTS, there are no 

expected impacts to the availability of 

marine mammals for subsistence uses 

due to the blasting activity. 

Based on the description of the 

specified activity, and the mitigation 

and monitoring measures, NMFS has 

determined that there will not be an 

unmitigable adverse impact on 

subsistence uses from USACE’s 

construction 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 NMFS Alaska Regional 

Office. 

There are two marine mammal 

species (western DPS Steller sea lion 

and humpback whale (Mexico and 

Western North Pacific DPSs)) with 

confirmed occurrence in the project area 

that are listed as endangered under the 

ESA. The NMFS Alaska Regional Office 

Protected Resources Division issued a 

Biological Opinion on November 16, 

2023 under section 7 of the ESA, on the 

issuance of an IHA to USACE under 

section 101(a)(5)(D) of the MMPA by the 

NMFS Permits and Conservation 

Division. The Biological Opinion 

concluded that the action is not likely 

to jeopardize the continued existence of 

Western DPS Steller sea lions or 

humpback whales from either the 

Mexico or Western North Pacific DPSs, 

and is not likely to destroy or adversely 

modify humpback whale critical habitat. 

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 

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 the USACE 

for conducting confined blasting in 

Iliuliuk Bay, Unalaska between January 

1, 2024 and December 31, 2024, 

incorporating the previously mentioned 

mitigation, monitoring, and reporting 

requirements. The IHA can be found at: 

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

incidental-take-authorization-us-armycorps-engineers-unalaska-dutch-harborchannel. 

Dated: November 20, 2023. 

Kimberly Damon-Randall, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2023–25934 Filed 11–22–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD512] 

Fisheries of the Exclusive Economic 

Zone Off Alaska; Bering Sea and 

Aleutian Islands Management Area; 

Cost Recovery Fee Notice for the 

Western Alaska Community 

Development Quota and Trawl Limited 

Access Privilege Programs 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice of standard prices and 

fee percentage. 

SUMMARY: NMFS publishes standard 

prices and fee percentages for cost 

recovery for the Amendment 80 

Program, the American Fisheries Act 

(AFA) Program, the Aleutian Islands 

Pollock (AIP) Program, and the Western 

Alaska Community Development Quota 

(CDQ) Program in the Bering Sea 

Aleutian Islands (BSAI) management 

area. The fee percentages for 2023 are 

1.37 percent for the Amendment 80 

Program, 0.26 percent for the AFA 

inshore cooperatives, 0 percent for the 

AIP program, and 1.07 percent for the 

CDQ Program. This notice is intended to 

provide the 2023 standard prices and 

fee percentages to calculate the required 

payment for cost recovery fees due by 

December 31, 2023. 

DATES: The standard prices and fee 

percentages are valid on November 24, 

2023. 

FOR FURTHER INFORMATION CONTACT: 

Charmaine Weeks, Fee Coordinator, 

907–586–7231. 

SUPPLEMENTARY INFORMATION: 

Background 

Section 304(d) of the MagnusonStevens Fishery Conservation and 

Management Act (Magnuson-Stevens 

Act) authorizes and requires that NMFS 

collect cost recovery fees for limited 

access privilege programs and the CDQ 

Program. Cost recovery fees include 

NMFS’ actual costs directly related to its 

management, data collection, and 

enforcement of the programs. Section 

304(d) of the Magnuson-Stevens Act 

mandates that cost recovery fees not 

exceed 3 percent of the annual ex-vessel 

value of fish harvested under any 

program subject to a cost recovery fee 

and that the fee be collected either at the 

time of landing, filing of a landing 

report, or sale of such fish during a 

fishing season or in the last quarter of 


ddrumheller on DSK120RN23PROD with NOTICES1