Federal Register / Vol. 88, No. 177 / Thursday, September 14, 2023 / Notices 63067 

(7) The excluded safe must be imported in 

the fully assembled condition. 

The scope also excludes metal storage 

devices that (1) have two or more exterior 

exposed drawers regardless of the height of 

the unit, or (2) are no more than 30 inches 

tall and have at least one exterior exposed 

drawer. 

Also excluded from the scope are free 

standing metal cabinets less than 30 inches 

tall with a single opening, single door and an 

installed tabletop. 

The scope also excludes metal storage 

devices less than 27 inches wide and deep 

that: (1) Have two doors hinged on the right 

and left side of the door frame respectively 

covering a single opening and that open from 

the middle toward the outer frame; or (2) are 

free standing or wall-mounted, singleopening units 20 inches or less high with a 

single door. 

The subject certain metal lockers are 

classified under Harmonized Tariff Schedule 

of the United States (HTSUS) subheading 

9403.20.0078. Parts of subject certain metal 

lockers are classified under HTS subheading 

9403.90.8041. In addition, subject certain 

metal lockers may also enter under HTS 

subheading 9403.20.0050. While HTSUS 

subheadings are provided for convenience 

and Customs purposes, the written 

description of the scope of the Orders is 

dispositive. 

[FR Doc. 2023–19897 Filed 9–13–23; 8:45 am] 

BILLING CODE 3510–DS–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD199] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Ferry Berth 

Construction in Tongass Narrows in 

Ketchikan, 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 the 

Alaska Department of Transportation 

and Public Facilities (ADOT&PF) to 

incidentally harass marine mammals 

during construction activities associated 

with ferry berth construction in Tongass 

Narrows in Ketchikan, Alaska. 

DATES: This authorization is effective 

from September 11, 2023 to September 

10, 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/national/ 

marine-mammal-protection/incidentaltake-authorizations-constructionactivities. In case of problems accessing 

these documents, please call the contact 

listed below. 

FOR FURTHER INFORMATION CONTACT: Kate 

Fleming, 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 January 24, 2023, NMFS received 

a request from ADOT&PF for an IHA to 

take marine mammals incidental to the 

construction of and improvements to 

four (initially five—see explanation 

below) ferry berths in Tongass Narrows 

in Ketchikan, Alaska. On February 23, 

2023, ADOT&PF submitted a memo 

proposing additional construction 

activities at this project site, which was 

later retracted on March 21, 2023. 

Following NMFS’ review of the 

application and discussions between 

NMFS and ADOT&PF, on May 2, 2023, 

ADOT&PF asked NMFS to halt 

processing of the IHA until it submitted 

an acoustic monitoring report associated 

with previous work at the project site. 

ADOT&PF submitted the report on May 

24, 2023. NMFS reviewed and accepted 

the results in the report, and the 

application was deemed adequate and 

complete on June 27, 2023. ADOT&PF’s 

request is for take of 11 species of 

marine mammals, by Level B 

harassment and, for Steller sea lion 

(Eumetopias jubatus), harbor seal 

(Phoca vitulina), northern elephant seal 

(Mirounga angustirostris), harbor 

porpoise (Phocoena phocoena), and 

Dall’s porpoise (Phocoenoides dalli), 

Level A harassment. Neither ADOT&PF 

nor NMFS expect serious injury or 

mortality to result from this activity 

and, therefore, an IHA is appropriate. 

NMFS previously issued two 

consecutive IHAs to ADOT&PF for this 

work (85 FR 673, January 7, 2020), 

which covered construction at the 

following six sites: Revilla New Ferry 

Berth and Upland Improvements 

(Revilla New Berth), New Gravina 

Island Shuttle Ferry Berth/Related 

Terminal Improvements (Gravina New 

Berth), Gravina Airport Ferry Layup 

Facility, Gravina Freight Facility, 

Revilla Refurbish Existing Ferry Berth 

Facility, and Gravina Refurbish Existing 

Ferry Berth Facility (Figure 1). Due to 

various project delays (and two minor 

changes to the phase 1 IHA activities), 

the phase 1 IHA was renewed (86 FR 

23938, May 05, 2021) and the phase 2 

IHA was reissued (87 FR 12117, March 

3, 2022). Upon the expiration of the 

phase 1 renewal, because a subset of 

work had still not been completed, 

ADOT&PF requested, and NMFS issued, 

a new IHA (87 FR 15387, March 18, 

2022) which was renewed upon its 

expiration (88 FR 13802, March 6, 

2023). The reissued phase 2 IHA 

expired on February 28, 2023. While the 

current renewal IHA (88 FR 13802, 

March 6, 2023) does not expire until 

March 5, 2024, ADOT&PF proposed 

new project components that warrant a 

new IHA, and a subset of activities 

covered under the reissued phase 2 IHA 

remain incomplete. As such, ADOT&PF 

requested a new IHA to authorize take 

of marine mammals associated with all 

remaining work at the Tongass Narrows 

sites. Work at the Gravina Airport Ferry 

Layup Facility was completed prior to 

the application for this new IHA. Since 

the submission of ADOT&PF’s 2023 IHA 


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application, work has also been 

completed at the Gravina Freight 

Facility. As such, remaining work 

planned is limited to four project sites: 

Revilla New Berth, Gravina New Berth, 

Revilla Refurbish Existing Ferry Berth 

Facility, and Gravina Refurbish Existing 

Ferry Berth Facility. ADOT&PF has 

complied with all the requirements (e.g., 

mitigation, monitoring, and reporting) of 

the previous IHAs with the exception of 

one incident in which ADOT&PF 

reported that a pile had been removed 

without the presence of a Protected 

Species Observer (PSO) on site. 

ADOT&PF reported the incident 

immediately and retrained the 

Construction Contractor’s Foreman and 

ADOT&PF’s on-site representative. 

ADOT&PF also notified NMFS on May 

18, 2023 that 12 20’’ piles that were not 

included in the renewal, but were 

included in the initial IHA on which the 

renewal was based, were driven after 

expiration of the initial IHA (while the 

renewal was effective). 

Monitoring results from the previous 

IHAs are discussed in the Potential 

Effects of Specified Activities on Marine 

Mammals and their Habitat and the 

Estimated Take of Marine Mammals 

section. 

Description of Specified Activity 

ADOT&PF is making improvements to 

two existing ferry berths and 

constructing two new ferry berths on 

Gravina Island and Revillagigedo 

(Revilla) Island in Tongass Narrows, 

near Ketchikan, in southeast Alaska (see 

Figure 1 of the notice of proposed IHA 

(88 FR 46746; July 20, 2023). The 

existing ferry facilities improve access 

to developable land on Gravina Island, 

improve access to the Ketchikan 

International Airport, and facilitate 

economic development in the Ketchikan 

Gateway Borough. The new ferry berths 

provide redundancy to the existing ferry 

berths. The project’s planned activities 

that have the potential to take marine 

mammals, by Level A harassment and 

Level B harassment, include down-thehole (DTH) drilling of rock sockets and 

tension anchors, vibratory installation 

and removal of temporary steel pipe 

piles and/or H-piles, vibratory and 

impact installation of permanent steel 

pipe piles, and vibratory removal of 

permanent piles (in cases where work is 

being redone). The marine construction 

associated with the planned activities is 

expected to occur over 131 nonconsecutive days over 1 year. 

A detailed description of the planned 

construction project is provided in the 

Federal Register notice for the proposed 

IHA (88 FR 46746, July 20, 2023). Since 

that time, no changes have been made 

to planned activities. Therefore, a 

detailed description is not provided 

here. Please refer to that Federal 

Register notice for the description of the 

specified activity. 

Comments and Responses 

A notice of NMFS’ proposal to issue 

an IHA to ADOT&PF was published in 

the Federal Register on July 20, 2023 

(88 FR 46746). That notice described, in 

detail, ADOT&PF’s 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. During the 30-day public 

comment period, NMFS did not receive 

any public comments. 

Changes From the Proposed IHA to 

Final IHA 

Since the Federal Register notice of 

the proposed IHA was published (88 FR 

46746, July 20, 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 

descriptions of the potentially affected 

stocks (see Table 1), attribution of take 

numbers to stock (see Estimated Take of 

Marine Mammals), 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, as requested by 

ADOT&PF, NMFS made two changes to 

the PSO requirements since publication 

of the proposed IHA. First, NMFS 

revised the requirement for PSOs to be 

independent of the activity contractor 

(for example, employed by a 

subcontractor), to reflect that PSOs must 

be independent (not be part of the 

construction crew) but not necessarily 

employed by a subcontractor. This 

change is intended to align this 

requirement with that in the active IHA 

to allow PSOs who are currently 

working on the project to continue to do 

so. Second, NMFS proposed to require 

ADOT&PF to employ three PSOs for 

DTH activities. After publication of the 

proposed IHA, ADOT&PF requested for 

NMFS to revise this measure to require 

two PSOs for DTH activities, given that 

the zone sizes for DTH activities, like 

those of impact pile driving, are small 

enough to be adequately monitored by 

two PSOs. NMFS concurred, and 

therefore, the final IHA requires 

ADOT&PF to employ at least two PSOs 

for DTH activities, rather than three. 

Finally, NMFS corrected a 

typographical error in Table 8 of the 

notice of the proposed IHA (88 FR 

46746, July 20, 2023). The table omitted 

the Level B harassment isopleth for DTH 

of tension anchors, which should have 

been listed as 1,274 m. The 

corresponding table in the proposed 

IHA at the time of publishing was 

correct. 

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’ SARs (https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/marinemammal-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. 


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Federal Register / Vol. 88, No. 177 / Thursday, September 14, 2023 / Notices 63069 

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 (Caretta et al., 2023, 

Young et al., 2023) and are available 

online at: https://

www.fisheries.noaa.gov/national/ 

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

TABLE 1—MARINE MAMMAL 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): 

Minke Whale 5 ................ Balaenoptera acutorostrata .. Alaska ................................... -,-,N N/A (N/A, N/A, N/A) ............. UND 0 

Fin Whale 6 ..................... Balaenoptera physalus ......... Northeast Pacific .................. E, D, Y 3,168 (0.26, 2,554, 2013) .... UND 0.6 

Humpback Whale 7 ......... Megaptera novaeangliae ...... Hawai1i .................................. -,-,N 11,278 (0.56, 7,265, 2020) .. 127 19.6 

Mexico—North Pacific .......... T, D, Y N/A (N/A, N/A, 2006) ........... UND 0.56 

Family Eschrichtiidae: 

Gray whale ..................... Eschrichtius robustus ........... Eastern North Pacific ........... -,-,N 26,960 (0.05, 25,849, 2016) 801 131 

Odontoceti (toothed whales, dolphins, and porpoises) 

Family Delphinidae: 

Pacific White-sided Dolphin.Lagenorhynchus obliquidens N Pacific ............................... -,-,N 26,880 (N/A, N/A, 1990) ...... UND 0 

Killer Whale .................... Orcinus orca ......................... Eastern North Pacific Alaska 

Resident.

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

Eastern North Pacific Northern Resident.-,-,N 302 (N/A, 302, 2018) ........... 2.2 0.2 

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

Family Phocoenidae (porpoises): 

Harbor Porpoise 8 ........... Phocoena phocoena ............ Southern Southeast Alaska 

Inland Waters.

-,-,Y 890 (0.37, 610, 2019) .......... 6.1 7.4 

Dall’s Porpoise 9 ............. Phocoenoides dalli ............... Alaska ................................... -,-,N 15,432 (0.097, 13,110, 2021) 131 37 

Order Carnivora—Pinnipedia 

Family Otariidae (eared seals 

and sea lions): 

Steller Sea Lion .............. Eumetopias jubatus .............. Eastern ................................. -,-,N 43,201 (N/A, 43,201, 2017) 2,592 112 

Family Phocidae (earless 

seals): 

Northern Elephant Seal .. Mirounga angustirostris ........ CA Breeding ......................... -,-,N 187,386 (N/A, 85,369, 2013) 5,122 13.7 

Harbor Seal .................... Phoca vitulina ....................... Clarence Strait ..................... -,-,N 27,659 (N/A, 24,854, 2015) 746 40 

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)). 2ESA 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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. 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. 5 No population estimates have been made for the number of minke whales in the entire North Pacific. Some information is available on the numbers of minke 

whales on some areas of Alaska, but in the 2009, 2013 and 2015 offshore surveys, so few minke whales were seen during the surveys that a population estimate for 

the species in this area could not be determined (Rone et al., 2017). Therefore, this information is N/A (not available). 6The best available abundance estimate for this stock is not considered representative of the entire stock as surveys were limited to a small portion of the stock’s 

range. Based upon this estimate and the Nmin, the PBR value is likely negatively biased for the entire stock. 7Abundance estimates for the Mexico-North Pacific Stock of humpback whale are based upon data collected more than 8 years ago and therefore, current estimates are considered unknown. 8Abundance estimates assumed that detection probability on the trackline was perfect; work is underway on a corrected estimate. Additionally, preliminary data results based on eDNA analysis show genetic differentiation between harbor porpoise in the northern and southern regions on the inland waters of southeast Alaska. 

Geographic delineation is not yet known. Data to evaluate population structure for harbor porpoise in Southeast Alaska have been collected and are currently being 

analyzed. Should the analysis identify different population structure than is currently reflected in the Alaska SARs, NMFS will consider how to best revise stock designations in the future. 9Previous 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 11 species 

(with 13 managed stocks) in Table 1 

temporally and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur. 

A detailed description of the species 

likely to be affected by ADOT&PF’s 

project, including brief introductions to 

the species and relevant stocks as well 

as available information regarding 

populations trends and threats, and 


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information regarding local occurrence, 

were provided in the Federal Register 

notice for the proposed IHA (88 FR 

46746, July 20, 2023).The 2022 Alaska 

and Pacific SARs described a revised 

stock structure for humpback whales 

which modifies the previous stocks 

designated under the MMPA to align 

more closely with the ESA-designated 

DPSs (Caretta et al., 2023; Young et al., 

2023). Specifically, the three previous 

North Pacific humpback whale stocks 

(Central and Western North Pacific 

stocks and a CA/OR/WA stock) were 

replaced by five stocks, largely 

corresponding with the ESA-designated 

DPSs. These include Western North 

Pacific and Hawaii stocks and a Central 

America/Southern Mexico-CA/OR/WA 

stock (which corresponds with the 

Central America DPS). The remaining 

two stocks, corresponding with the 

Mexico DPS, are the Mainland MexicoCA/OR/WA and Mexico-North Pacific 

stocks (Caretta et al., 2023; Young et al., 

2023). The former stock is expected to 

occur along the west coast from 

California to southern British Columbia, 

while the latter stock may occur across 

the Pacific, from northern British 

Columbia through the Gulf of Alaska 

and Aleutian Islands/Bering Sea region 

to Russia. 

In the proposed IHA, NMFS stated 

that the Central North Pacific stock of 

humpback whale was likely to be 

impacted by ADOT&PF’s activities. 

Given the revised stock structure, NMFS 

has reanalyzed the potential for take of 

each stock of humpback whale and 

determined that the Hawaii stock and 

the Mexico- North Pacific stock are 

likely to be impacted by ADOT&PF’s 

activities. 

The 2022 Alaska SARs described a 

revised stock structure for southeast 

Alaska harbor porpoise, which were 

split from one stock into three: the 

Northern Southeast Alaska Inland 

Waters, Southern Southeast Alaska 

Inland Waters, and Yakutat/Southeast 

Alaska Offshore Waters harbor porpoise 

stocks (Young et al., 2023). This update 

better aligns harbor porpoise stock 

structure with genetics, trends in 

abundance, and information regarding 

discontinuous distribution trends 

(Young et al., 2023). Harbor porpoises 

found in the Tongass Narrows area are 

assumed to be members of the Southern 

Southeast Alaska Inland Waters stock, 

based on the geographical range of the 

stock. Please refer to the notice of the 

proposed IHA (88 FR 46746, July 20, 

2023) for species descriptions. Please 

also refer to the NMFS’ website (https:// 

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

generalized species accounts, and to the 

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

national/marine-mammal-protection/ 

marine-mammal-stock-assessments) for 

more information about the changes to 

humpback whale and harbor porpoise 

stock structures. 

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 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 

ADOT&PF’s construction 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 46746, July 

20, 2023) included a discussion of the 

effects of anthropogenic noise on marine 

mammals and the potential effects of 

underwater noise from ADOT&PF’s 

construction activities on marine 

mammals and their habitat. That 

information and analysis is incorporated 

by reference into these final IHA 

determinations and is not repeated here; 

please refer to the Federal Register 

notice of proposed IHA (88 FR 46746, 

July 20, 2023). 

Estimated Take of Marine Mammals 

This section provides an estimate of 

the number of incidental takes 

authorized through this IHA, which 


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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 will primarily be by 

Level B harassment, as use of the 

acoustic sources (i.e., impact and 

vibratory pile driving and removal and 

DTH) has the potential to result in 

disruption of behavioral patterns for 

individual marine mammals. There is 

also some potential for auditory injury 

(Level A harassment) to result, primarily 

for high frequency cetaceans, phocids, 

and otariids because predicted auditory 

injury zones are larger than for other 

hearing groups. Auditory injury is 

unlikely to occur for other groups. 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 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., impact pile 

driving) or intermittent (e.g., scientific 

sonar) sources. This take estimation 

includes disruption of behavioral 

patterns resulting directly in response to 

noise exposure (e.g., avoidance), as well 

as the resulting indirectly form the 

associated impacts such as Temporary 

Threshold Shift (TTS) or masking. 

ADOT&PF’s planned activity includes 

the use of continuous (vibratory pile 

driving/removal and DTH) and 

impulsive (impact pile driving and 

DTH) 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). ADOT&PF’s planned 

activity includes the use of impulsive 

(impact pile driving and DTH) and nonimpulsive (vibratory pile driving/ 

removal and DTH) sources. 

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: 

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

national/marine-mammal-protection/ 

marine-mammal-acoustic-technicalguidance. 

TABLE 3—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset thresholds * 

(received level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans .................................... Cell 1: Lp,0-pk,flat: 219 dB; LE,p,LF,24h: 183 dB ............... Cell 2: LE,p,LF,24h: 199 dB. 

Mid-Frequency (MF) Cetaceans .................................... Cell 3: Lp,0-pk,flat: 230 dB; LE,p,MF,24h: 185 dB ............... Cell 4: LE,p,MF,24h: 198 dB. 

High-Frequency (HF) Cetaceans .................................. Cell 5: Lp,0-pk,flat: 202 dB; LE,p,HF,24h: 155 dB ............... Cell 6: LE,p,HF,24h: 173 dB. 

Phocid Pinnipeds (PW) (Underwater) ........................... Cell 7: Lp,0-pk.flat: 218 dB; LE,p,PW,24h: 185 dB .............. Cell 8: LE,p,PW,24h: 201 dB. 

Otariid Pinnipeds (OW) (Underwater) ........................... Cell 9: Lp,0-pk,flat: 232 dB; LE,p,OW,24h: 203 dB .............. Cell 10: LE,p,OW,24h: 219 dB. 

* Dual metric 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 are recommended 

for consideration. 


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Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 μPa, and weighted cumulative sound exposure level (LE,p) has a reference value of 1μPa2s. In this Table, thresholds are abbreviated to be more reflective of International Organization for Standardization standards (ISO 2017). The subscript ‘‘flat’’ is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized 

hearing range of marine mammals (i.e., 7 Hz to 160 kHz). 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 weighted 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 

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, 

vibratory pile driving and removal, and 

DTH). 

The intensity of pile driving sounds is 

greatly influenced by factors such as the 

type of piles (material and diameter), 

hammer type, and the physical 

environment (e.g., sediment type) in 

which the activity takes place. The 

ADOT&PF evaluated SPL measurements 

available for certain pile types and sizes 

from similar activities elsewhere to 

determine appropriate proxy levels for 

their planned activities. The ADOT&PF 

also initially referred to preliminary 

results from a sound source verification 

study to determine SPLs for DTH of 

8-inch tension anchors and 

Transmission Loss values (TLs) for all 

DTH activities. As discussed in the 

Summary of Request section above, a 

Sound Source Verification (SSV) report 

detailing sound source values and TL 

coefficients collected at the project site 

was subsequently submitted. 

To determine appropriate proxy SPLs 

for impact and vibratory pile driving of 

all pile types, NMFS completed a 

comprehensive review of source levels 

relevant to Southeast Alaska to generate 

regionally-specific source levels. NMFS 

compiled all available data from Puget 

Sound and Southeast Alaska and 

adjusted the data to standardize 

distance from the measured pile to 10 

meters (m). NMFS then calculated 

average source levels for each project 

and for each pile type. NMFS weighted 

impact pile driving project averages by 

the number of strikes per pile following 

the methodology in Navy (2015). The 

source levels for these various pile 

types, sizes and methods are listed in 

Table 4. Additionally, ADOT&PF 

requested, and NMFS agreed, to use the 

24-inch sound source values for impact 

or vibratory pile driving of 14-inch 

H-piles, because the source value of 

smaller piles of the same general type 

(steel) are not expected to exceed a 

larger pile. 

NMFS recommends treating DTH 

systems as both impulsive and 

continuous, non-impulsive sound 

source types simultaneously. Thus, 

impulsive thresholds are used to 

evaluate Level A harassment, and 

continuous thresholds are used to 

evaluate Level B harassment. NMFS 

(2022) recommended guidance on DTH 

systems (https://

media.fisheries.noaa.gov/2022-11/ 

PUBLIC%20DTH%20Basic

%20Guidance_November%202022.pdf) 

outlines its recommended source levels 

for DTH systems. NMFS has applied 

that guidance in this analysis (see Table 

4 for NMFS’ source levels). Note that the 

values in this table represent the SPL 

referenced to a distance of 10 m (33 

(feet) ft) from the source. 

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 

Absent site-specific acoustical 

monitoring with differing measured 

transmission loss, a practical spreading 

value of 15 is used as the transmission 

loss coefficient in the above formula. 

Site-specific transmission loss data for 

the Tongass Narrows are not available 

for vibratory pile installation and 

removal and impact pile driving; 

therefore, the default coefficient of 15 is 

used to determine the distances to the 

Level A harassment and Level B 

harassment thresholds for these 

activities and associated pile types. In 

the case of DTH activities, ADOT&PF 

conducted SSV at the project site for 

DTH of 24-inch rock sockets and 8-inch 

tension anchors. NMFS reviewed the TL 

data from this monitoring and has 

incorporated the most conservative 

transmission loss values measured for 

each pile type at the project site in its 

analysis herein (Table 4). 

TABLE 4—ESTIMATES OF MEAN UNDERWATER SOUND LEVELS GENERATED DURING VIBRATORY AND IMPACT PILE

INSTALLATION, DTH, AND VIBRATORY PILE REMOVAL

RMS SPL 

(dB re 1 μPa) 

SELss

(dB re 1 μPa 2 sec) 

Peak SPL 

(dB re 1 μPa) 

References levels 

(TL) 

TL 

coefficient 1

Vibratory Hammer 

30-inch steel piles ................. 166 NA NA NMFS Analysis—C. Hotchkin April 24, 

2023.

15 

24-inch steel piles ................. 163 NA NA NMFS Analysis—C. Hotchkin April 24, 

2023.

15 

Steel 14′′ H-piles 2 ................. 163 NA NA 24-inch as proxy ...................................... 15 

DTH of Rock Sockets and Tension Anchors—Continuous 

24-inch (Rock Socket) ........... 167 NA NA Heyvaert & Reyff 2021; (Reyff and 

Ambaskar 2023).

19.5 


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TABLE 4—ESTIMATES OF MEAN UNDERWATER SOUND LEVELS GENERATED DURING VIBRATORY AND IMPACT PILE

INSTALLATION, DTH, AND VIBRATORY PILE REMOVAL—Continued 

RMS SPL 

(dB re 1 μPa) 

SELss

(dB re 1 μPa 2 sec) 

Peak SPL 

(dB re 1 μPa) 

References levels 

(TL) 

TL 

coefficient 1

8-inch DTH (Tension Anchor) 156 NA NA Reyff & Heyvaert 2019; Reyff 2020; 

(Reyff and Ambaskar 2023).

17.1 

Impact Hammer 

30-inch steel piles ................. 195 183 210 NMFS Analysis—C. Hotchkin April 24, 

2023.

15 

24-inch steel piles ................. 190 177 203 Caltrans 2015, Caltrans 2020 .................. 15 

Steel 14′′ H-piles 2 ................. 190 177 203 24-inch as proxy ...................................... 15 

DTH of rock sockets and tension anchors—Impulsive 

24-inch (Rock Socket) ........... NA 159 184 Heyvaert & Reyff 2021; (Reyff and 

Ambaskar 2023).

19.9 

8-inch (Tension anchor) ........ NA 144 170 Reyff 2020; (Reyff and Ambaskar 2023) 17.1 

1 NMFS recommends a default transmission loss of 15 * log10(R) when site-specific data are not available (NMFS, 2020; NMFS, 2022). 2For 14-inch H piles, NMFS uses sound source level data from 24-inch piles as a conservative proxy. 

Note: all SPLs are unattenuated and represent the SPL referenced to a distance of 10 m from the source; NA = Not applicable; dB re 1 μPa = 

decibels (dB) referenced to a pressure of 1 microPascal, measures underwater SPL; dB re 1 μPa2-sec = dB referenced to a pressure of 1 microPascal squared per second, measures underwater Sound Exposure Level (SEL). 

All Level B harassment isopleths are 

reported in Table 5 below. Of note, 

based on the geography of Tongass 

Narrows and the surrounding islands, 

sound will not reach the full distance of 

the Level B harassment isopleth in most 

directions. Generally, due to interaction 

with land, only a thin slice of the 

possible area will be ensonified to the 

full distance of the Level B harassment 

isopleth. 

TABLE 5—LEVEL B HARASSMENT ISOPLETHS BY ACTIVITY AND PILE SIZE

Activity Pile diameter 

(inch) 

Level B 

harassment isopleth 

(m) 

Vibratory Installation and Removal .......................................................................................................... 30 

24 

14 

11,659 

7,365 

DTH Rock Sockets .................................................................................................................................. 24 2,572 

DTH Tension Anchor ............................................................................................................................... 8 1,274 

Impact Installation .................................................................................................................................... 30 

24 

14 

2,154 

1,000 

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 driving or removal 

or DTH using any of the methods 

discussed above, 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 is expected to incur PTS. 

Inputs used in the optional User 

Spreadsheet tool, and the resulting 

estimated isopleths, are reported in 

Table 6 and Table 7. 

TABLE 6—NMFS USER SPREADSHEET INPUTS

Vibratory pile driving DTH Impact 

30-inch steel piles 24-inch steel piles or 

steel H-pile 

Rock socket 

(24 inch) 

Tension anchor 

(8-inch) 30-inch steel piles 24-inch steel piles or steel H-pile 

Installation 

or removal 

Installation 

or removal Installation Installation Installation Installation 

Spreadsheet Tab Used A.1) Vibratory Pile 

Driving.

A.1) Vibratory Pile 

Driving.

E.2) DTH Pile Driving.E.2) DTH Pile Driving.E.1) Impact Pile Driving.E.1) Impact Pile Driving. 

Source Level (SPL) .... 166 RMS .................. 163 RMS .................. 167 RMS, 159 SEL .. 156 RMS, 144 SEL .. 183 SEL ................... 177 SEL. 


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TABLE 6—NMFS USER SPREADSHEET INPUTS—Continued 

Vibratory pile driving DTH Impact 

30-inch steel piles 24-inch steel piles or 

steel H-pile 

Rock socket 

(24 inch) 

Tension anchor 

(8-inch) 30-inch steel piles 24-inch steel piles or steel H-pile 

Installation 

or removal 

Installation 

or removal Installation Installation Installation Installation 

Transmission Loss Coefficient.15 ............................. 15 ............................. 19.5, 19.9 ................. 17.1, 17.1 ................. 15 ............................. 15. 

Weighting Factor Adjustment (kHz).2.5 ............................ 2.5 ............................ 2 ............................... 2 ............................... 2 ............................... 2. 

Activity Duration 

(hours) within 24 

hours.

0.5–6 * ...................... 0.5–8 * ...................... 1–8 ........................... 1–8.

Strike rate strike per 

second.

.................................. .................................. 10 ............................. 19.

Number of strikes per 

pile.

.................................. .................................. .................................. .................................. 50 (temporary); 200 

(permanent).

50 (temporary); 200 

(permanent). 

Number of piles per 

day.

1–6 ........................... 1–8 ........................... 1 ............................... 1 ............................... 1–3 ........................... 1–3. 

Distance of sound 

pressure level measurement.

10 ............................. 10 ............................. 10 ............................. 10 ............................. 10 ............................. 10. 

* A range of activity durations (vibratory and DTH), strikes per pile (impact), piles per day are listed because ADOT&PF anticipates that they can install or remove 

piles of the same size at different rates at different sites. Duration estimates for DTH assume that multiple rock sockets and tension anchors will be installed each 

day, with a maximum daily duration of 8 hours. 

Level A harassment thresholds for 

impulsive sound sources (impact pile 

driving and DTH) are defined for both 

cumulative sound exposure level 

(SELcum) and Peak SPL with the 

threshold that results in the largest 

modeled isopleth for each marine 

mammal hearing group used to establish 

the Level A harassment isopleth. In this 

project, Level A harassment isopleths 

based on SELcum were always larger 

than those based on Peak SPL. It should 

be noted that there is a duration 

component when calculating the Level 

A harassment isopleth based on 

SELcum, and this duration depends on 

the number of piles that will be driven 

in a day and strikes per pile. For some 

activities, ADOT&PF plans to drive 

variable numbers of piles per day 

throughout the project (See ‘‘Average 

Piles per Day (Range)’’ in Table 1 of the 

Federal Register notice for the proposed 

IHA, (88 FR 46746, July 20, 2023)). 

NMFS accounted for this variability in 

its analysis. For each activity, 

ADOT&PF provided the minimum and 

maximum potential durations of the 

activity. In some cases the difference in 

the Level A harassment zone size 

between the minimum and maximum 

duration anticipated for an activity for 

a given hearing group is quite large. 

ADOT&PF expressed concerns about 

implementing the largest Level A 

harassment zones for an activity on days 

where activity levels would be much 

lower, particularly given that the 

shutdown zones for an activity (Table 9) 

are based upon the Level A harassment 

zone sizes. Therefore, for low frequency 

cetaceans and phocids, in order to 

provide flexibility while ensuring the 

number of Level A harassment zones 

and associated shutdown zones are 

manageable, NMFS has identified two 

Level A harassment isopleths for a given 

activity in cases where the differences 

between zone sizes associated with the 

minimum and maximum potential 

activity duration spans >100 m. At the 

beginning of each pile driving day, 

ADOT&PF will determine the maximum 

number or duration that piles will be 

driven that day and implement the 

Level A harassment zone associated 

with that amount of activity. 

TABLE 7—DISTANCES TO LEVEL A HARASSMENT ISOPLETHS, BY HEARING GROUP, AND LEVEL B HARASSMENT ZONES, 

DURING PILE INSTALLATION AND REMOVAL

Activity 

Pile 

diameter(s) 

(inches) 

Max. daily 

duration/ 

number of 

piles * 

Level A harassment Isopleths, by hearing group (m) 

Level B 

harassment 

isopleth 

(m; hearing 

groups) 

LF MF HF PW 

Minke OW 

whale, fin 

whale, 

humpback 

whale, gray 

whale 

Pacific 

white-sided 

dolphin, 

killer 

whale 

Harbor 

porpoise, 

Dall’s 

porpoise 

Harbor seal, 

northern 

elephant 

seal 

Steller 

sea lion 

Vibratory Installation 

or Removal ........... 30 

24 or 14 

≤360 

≤480 

48.6 

37.1 

4.3 

3.3 

71.8 

54.9 

29.5 

22.6 

2.1 

1.6 

11,659 

7,356 

DTH (Rock Socket) .. 24 ≤120 

121–180 

181–480 

210.3 

....................

344.3 

27.8 

....................

....................

392.8 

....................

....................

107.1 

214.9 

....................

29.8 

....................

....................

2,572 

....................

....................

DTH (Tension Anchor) ..................... 8 ≤480 118.7 6.4 138.4 68.6 6.9 1,274 

Impact, 200 strikes ... 30 1 

2 

3 

542.1 

....................

710.4 

25.3 

....................

....................

846.2 

....................

....................

182.8 

380.2 

....................

27.7 

....................

....................

2,154 

....................

....................


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TABLE 7—DISTANCES TO LEVEL A HARASSMENT ISOPLETHS, BY HEARING GROUP, AND LEVEL B HARASSMENT ZONES, 

DURING PILE INSTALLATION AND REMOVAL—Continued 

Activity 

Pile 

diameter(s) 

(inches) 

Max. daily 

duration/ 

number of 

piles * 

Level A harassment Isopleths, by hearing group (m) 

Level B 

harassment 

isopleth 

(m; hearing 

groups) 

LF MF HF PW 

Minke OW 

whale, fin 

whale, 

humpback 

whale, gray 

whale 

Pacific 

white-sided 

dolphin, 

killer 

whale 

Harbor 

porpoise, 

Dall’s 

porpoise 

Harbor seal, 

northern 

elephant 

seal 

Steller 

sea lion 

24 or 14 1 

2 

3 

136.0 

282.8 

....................

10.1 

....................

....................

336.9 

....................

....................

72.8 

151.4 

....................

11.0 

....................

....................

1,000 

....................

....................

Impact, 50 strikes ..... 24 or 14 1–3 112.2 4.0 133.7 60.1 4.4 1,000 

* For low frequency cetaceans and phocids, in cases where the Level A harassment zone spanned ≥100 m between the minimum and maximum duration for the same activity, NMFS analyzed a shorter activity duration to allow for flexibility. 

Marine Mammal Occurrence and Take 

Estimation 

In this section we provide information 

about the occurrence of marine 

mammals, including density, or group 

dynamics of marine mammals, that will 

inform the take calculations. 

Additionally, we describe how the 

occurrence information is synthesized 

to produce a quantitative estimate of the 

take that is reasonably likely to occur 

and authorized. Note that take estimates 

included in ADOT&PF’s application 

reflect 152 construction days rather than 

131 (see Summary of Request section, in 

which it is described that one site has 

been completed since submission of the 

application). A summary of take, 

including a percentage of population for 

each of the species, is shown in Table 

8. 

Minke Whale 

There are no known occurrences of 

minke whales within the project area. 

No minke whales where reported during 

ADOT&PF’s previous construction 

activities at the project site (ADOT&PF 

2021, 2023), nor during other recent 

projects in the Tongass Narrows (e.g., 

City of Ketchikan (COK) Rock Pinnacle 

Blasting Project, Sitkiewicz 2020, Ward 

Cove Cruise Ship Dock in 2020, Power 

Systems and Supplies of Alaska, 2020). 

However, since their range extends into 

the project area, and they have been 

observed in southeast Alaska, including 

in Clarence Strait (Dahlheim et al., 

2009), it is possible the species could 

occur in the project area. Still, future 

observations of minke whale in the 

project area are expected to be rare. 

ADOT&PF conservatively requested 

take by Level B harassment of three 

minke whales every 4 months across the 

12 months that the IHA is active. NMFS 

concurs with ADOT&PF’s estimated 

group size and frequency, but finds it 

more appropriate to estimate take 

according to the number of actual 

months in which construction is 

planned. As such, NMFS conservatively 

authorizes four takes by Level B 

harassment (3 minke whales × 1.25 

months = 4 takes by Level B 

harassment). 

ADOT&PF is planning to implement 

shutdown zones for low-frequency 

cetaceans that exceed the Level A 

harassment isopleth for all activities. 

Therefore, especially in combination 

with the infrequent occurrence of minke 

whales entering the project area, 

implementation of the established 

shutdown zones is expected to 

eliminate the potential for take by Level 

A harassment of minke whale. 

Therefore, ADOT&PF did not request 

take by Level A harassment of minke 

whale, nor is NMFS authorizing any. 

Fin Whale 

Fin whales typically inhabit deep, 

offshore waters and often travel in open 

seas away from coasts, and are often 

observed in social groups of two to 

seven. However, a single fin whale was 

recently observed in Clarence Strait 

(Scheurer, personal communication). 

Since the ensonified area extends to the 

mouth of Tongass Narrows, where it 

meets Clarence Strait, there is a chance 

that fin whale could occur in the project 

area during construction. As such, 

NMFS conservatively authorizes two 

takes by Level B harassment of fin 

whale. 

ADOT&PF is planning to implement 

shutdown zones for low-frequency 

cetaceans that exceed the Level A 

harassment isopleth for all activities. 

Therefore, especially given the rare 

occurrence of fin whale in the 

surrounding area, implementation of the 

established shutdown zones is expected 

to eliminate the potential for take by 

Level A harassment of fin whale. 

Therefore, ADOT&PF did not request 

take by Level A harassment of fin whale, 

nor is NMFS authorizing any. 

Humpback Whale 

While no systematic studies have 

documented humpback whale 

abundance near Ketchikan, anecdotal 

information suggests that this species is 

present in low numbers year-round in 

Tongass Narrows. Additionally, during 

ADOT&PF’s 215 days of monitoring 

associated with previous construction, 

80 humpback whales were observed, or 

0.37 humpback whales per day 

(ADOT&PF 2021, 2023). According to 

ADOT&PF, the average group size was 

1.25 humpback whales, and the 

maximum group size was 4. 

ADOT&PF conservatively estimates, 

and NMFS concurs, that one humpback 

whale may occur in the Level B 

harassment zone each day of planned 

in-water work (1 humpback whale × 131 

days = 131 takes by Level B 

harassment). 

ADOT&PF is planning to implement 

shutdown zones for low-frequency 

cetaceans that exceed the Level A 

harassment isopleth for all activities. 

Therefore, implementation of the 

established shutdown zones is expected 

to eliminate the potential for take by 

Level A harassment of humpback whale. 

Therefore, ADOT&PF did not request 

take by Level A harassment of 

humpback whale, nor is NMFS 

authorizing any. 

In the proposed IHA, NMFS 

anticipated that all takes of humpback 

whale would be of the Central North 

Pacific stock. Given the revised stock 

structure described in the Description of 

Marine Mammals in the Area of 

Specified Activities section, NMFS has 

reanalyzed the potential for take of each 

stock of humpback whale and 

anticipates that the authorized takes 

would be of the new Hawaii stock and 


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new Mexico-North Pacific stock. To 

determine the number of estimated 

takes of each stock, NMFS assumes that 

two percent of humpback whales 

occurring in Southeast Alaska are from 

the Mexico-North Pacific stock and the 

remaining humpback whales are from 

the Hawai’i stock (Wade et al., 2021). 

Gray Whale 

Gray whales are rare in the project 

area and unlikely to occur in Tongass 

Narrows. They were not observed 

during the Dahlheim et al. (2009) 

surveys of Alaska’s inland waters with 

surveys conducted in the spring, 

summer and fall months. No gray 

whales where reported during 

ADOT&PF’s previous construction 

activities at the project site (ADOT&PF 

2021, 2023), nor during other recent 

projects in the Tongass Narrows (e.g., 

COK Rock Pinnacle Blasting Project, 

Sitkiewicz 2020; Ward Cove Cruise Ship 

Dock in 2020, Power Systems and 

Supplies of Alaska, 2020). However a 

gray whale could migrate through or 

near the project, during November 

especially. Gray whales are generally 

solitary and travel together, alone, or in 

small groups. 

ADOT&PF requested 24 takes by 

Level B harassment of gray whales (1 

group × 2 gray whales × 12 months that 

the IHA is active). NMFS concurs with 

ADOT&PF’s estimated group size and 

frequency, but finds it more appropriate 

to base take estimates on planned 

duration of in-water work. As such, 

NMFS authorizes 10 takes by Level B 

harassment (1 group × 2 gray whales × 

5 months = 10 takes by Level B 

harassment). 

ADOT&PF is planning to implement 

shutdown zones for low-frequency 

cetaceans that exceed the Level A 

harassment isopleth for all activities. 

Therefore, especially in combination 

with the low occurrence of gray whales 

in the project area, implementation of 

the planned shutdown zones is 

expected to eliminate the potential for 

take by Level A harassment of gray 

whale. Therefore, ADOT&PF did not 

request take by Level A harassment of 

gray whale, nor is NMFS authorizing 

any. 

Pacific White-Sided Dolphin 

Pacific white-sided dolphins were not 

observed during the 215 days of marine 

mammal monitoring associated with 

ADOT&PF’s previous construction 

activities at this site (ADOT&PF 2021, 

2023). There were also no sightings of 

Pacific white-sided dolphins during 

previous monitoring conducted during 

other recent construction projects in the 

Tongass Narrows (Sitkiewicz 2020, 

Power Systems and Supplies of Alaska, 

2020). 

While rare in the inside passageways 

of Southeast Alaska, a group of 164 

Pacific white-sided dolphins were 

observed in the Dixon entrance to the 

south of Tongass Narrows during aerial 

surveys in 1997 (Muto et al. 2018), and 

this species was also documented in 

Revillagigedo Channel, Behm Canal, 

and Clarence Strait during surveys 

conducted from April to May between 

1991 and 1993 (Dahlheim and Towell 

1994). Finally, Dalheim et al. (2009) 

frequently encountered Pacific whitesided dolphins in Clarence Strait. 

Observations were noted most typically 

in open strait environments, near the 

open ocean. Mean group size was over 

20, with no recorded winter 

observations nor observations made in 

the Nichols Passage or Behm Canal, 

located on either side of the Tongass 

Narrows. This observational data, 

combined with anecdotal information, 

indicates that while Pacific white-sided 

dolphins are rare in the area, they could 

occur in the project area during 

construction. 

ADOT&PF requested Level B 

harassment take of one group of 50 

Pacific white-sided dolphins. However, 

to remain consistent with mean groups 

sizes detected near Tongass Narrows 

(Dalheim et al., 2009), NMFS is 

authorizing three groups of 20 pacific 

white sided dolphins (60 takes by Level 

B harassment of Pacific white-sided 

dolphin). 

ADOT&PF is planning to implement 

shutdown zones for mid-frequency 

cetaceans that exceed the Level A 

harassment isopleth for all activities. 

Additionally, the Level A harassment 

isopleths for mid-frequency cetaceans 

are quite small, and therefore, shutdown 

zones should be easily implemented. 

Therefore, especially in combination 

with the low occurrence of Pacific 

white-sided dolphins in the project area, 

implementation of the established 

shutdown zones is expected to 

eliminate the potential for take by Level 

A harassment of Pacific white-sided 

dolphin. Therefore, ADOT&PF did not 

request take by Level A harassment of 

Pacific white-sided dolphin, nor is 

NMFS is authorizing any. 

Killer Whale 

While no systematic studies of killer 

whales have been conducted in or 

around Tongass Narrows, killer whales 

are observed in Tongass Narrows yearround, and anecdotal reports suggest 

they are most common during the 

summer Chinook salmon run (May– 

July) (84 FR 36891, July 30, 2019). 

Across the 215 days of monitoring 

during ADOT&PF’s previous Tongass 

Narrows construction activities, a total 

of 78 killer whales were observed, for an 

observation rate of 0.36 per day 

(ADOT&PF 2021, 2023). According to 

ADOT&PF, the average group size 

observed was 4.6 killer whales and the 

maximum group size was 8. 

While ADOT&PF requested 180 takes 

by Level B harassment ((1 group × 12 

killer whales × 9 months) + (2 groups × 

12 killer whales × 3 months) = 180 takes 

by Level B harassment)), NMFS finds it 

more appropriate to base take estimates 

off the maximum group size (8 killer 

whales) observed during monitoring of 

previous construction activities and the 

planned duration of in-water work (5 

months). As such, NMFS authorizes 64 

takes by Level B harassment ((2 pods × 

8 killer whales × 3 months) + (1 pod × 

8 killer whales × 2 months) = 64 takes 

by Level B harassment). 

ADOT&PF is planning to implement 

shutdown zones for mid-frequency 

cetaceans that exceed the Level A 

harassment isopleth for all activities. 

Additionally, the Level A harassment 

isopleths for mid-frequency cetaceans 

are quite small and therefore shutdown 

zones should be easily implemented. 

Therefore, implementation of the 

established shutdown zones is expected 

to eliminate the potential for take by 

Level A harassment of killer whale. 

Therefore, ADOT&PF did not request 

take by Level A harassment of killer 

whale, nor is NMFS authorizing any. 

Harbor Porpoise 

Abundance data for harbor porpoise 

in Southeast Alaska were collected 

during 18 seasonal surveys spanning 22 

years, from 1991 to 2012 (Dahlheim et 

al. 2015). The project area falls within 

the Clarence Strait to Ketchikan region, 

as identified by this study for the survey 

effort. Harbor porpoise densities in this 

region in summer were low, ranging 

from 0.01 to 0.02 harbor porpoises/ 

kilometers2. During ADOT&PF’s 215 

days of monitoring during previous 

construction activities at this project 

site, the daily average observations of 

harbor porpoise in the project area was 

0.1 (ADOT&PF 2021, 2023). According 

to ADOT&PF, the maximum group size 

observed during this monitoring was 

five. 

ADOT&PF estimates that two groups 

of five harbor porpoise may occur in the 

Level B harassment zone across the 12 

months that the IHA is active. NMFS 

concurs with ADOT&PF’s estimated 

group size but finds it appropriate to 

increase the frequency of occurrence 

estimate in the Level B harassment zone 

from two groups per month to three 

groups per month of work. Additionally, 


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NMFS finds it more appropriate to 

estimate take by Level B harassment 

according to the planned duration of inwater work (3 groups × 5 harbor 

porpoises × 5 months = 75 takes by 

Level B harassment). Additionally, 

ADOT&PF requested take by Level A 

harassment of one group of five harbor 

porpoise every 4 months across 12 

months that the IHA is active. However, 

NMFS finds it more appropriate to 

estimate take by Level A harassment 

according to the number of months in 

which the Level A harassment zone may 

extend beyond the established 

shutdown zone (i.e., 2.9 months, when 

DTH systems may be employed to 

install 24-inch piles, or 24-inch and 30- 

inch piles may be installed with an 

impact pile driver (200 strikes)). As 

such, NMFS authorizes 15 takes by 

Level A harassment of harbor porpoise 

(1 group × 5 harbor porpoise × 2.9 

months = 15 takes by Level B 

harassment) and 60 takes by Level B 

harassment ((3 groups × 5 harbor 

porpoise × 5 months)¥15 takes by Level 

A harassment = 60 takes by Level B 

harassment). 

In the proposed IHA, NMFS 

anticipated that all takes of harbor 

porpoise would be of the Southern 

Southeast Alaska Inland Water stock. 

Given the revised stock structure 

described in the Description of Marine 

Mammals in the Area of Specified 

Activities section, NMFS has reanalyzed 

the potential for take of each stock of 

harbor porpoise and anticipates that the 

authorized takes would be of the new 

Southern Southeast Alaska Inland 

Waters stock, as that is the only stock 

that overlaps the project area. 

Dall’s Porpoise 

Dall’s porpoise have occasionally 

been observed during previous 

construction projects completed in 

Tongass Narrows (Power Systems and 

Supplies of Alaska, 2020), including 

during ADOT&PF’s 215 days of 

monitoring (ADOT&PF 2021, 2023). 

ADOT&PF reported that the average 

group size observed was 5.6 and the 

maximum group size was 10. To 

estimate take, ADOT&PF has assumed 

that Dall’s porpoise may occur in pods 

of 15 and across the 12 months that the 

IHA is active. NMFS finds it more 

appropriate to base take estimates off 

the maximum group size (10 Dall’s 

porpoise) observed during monitoring of 

previous construction activities and 

according to estimated duration of 

planned pile driving and DTH activities. 

As such, while ADOT&PF estimates 

that one pod of 15 Dall’s porpoise may 

occur within the Level B harassment 

zone across each of the 12 months that 

the IHA is active, NMFS finds it more 

appropriate to conservatively estimate 

that 2 pods of 10 Dall’s porpoise may 

occur in the Level B harassment zone 

each month in which in-water work is 

planned (2 pod × 10 Dall’s porpoise × 

5 months = 100). 

Additionally, ADOT&PF has 

estimated that one pod of 15 Dall’s 

porpoise may occur within the Level A 

harassment zone across the 12 months 

that the IHA is active. However, NMFS 

finds it more appropriate to estimate 10 

takes by Level A harassment of Dall’s 

porpoise across the 2.9 months in which 

the Level A harassment zone may 

extend beyond the shutdown zone for 

this species, which could occur when 

DTH systems are employed to install 24- 

inch piles or an impact pile driver (200 

strikes) is used to install 24-inch and 30- 

inch piles (1 group × 10 Dall’s porpoise 

= 10 takes by Level A harassment). 

Therefore, NMFS is authorizing 10 takes 

by Level A harassment of Dall’s 

porpoise. Finally, the authorized take by 

Level B harassment has been calculated 

as the total calculated Dall’s porpoise 

takes by Level B harassment minus the 

authorized takes by Level A harassment 

(100 takes by Level B harassment¥10 

takes by Level A harassment = 90 takes 

by Level B harassment). Therefore, 

NMFS is authorizing 90 takes by Level 

B harassment of Dall’s porpoise. 

Steller Sea Lion 

Steller sea lions may be found in 

Tongass Narrows year-round, with 

anecdotal reports suggesting an increase 

in abundance from March to early May 

during the herring spawning season, 

and another increase in late summer 

associated with salmon runs. During the 

215 days of marine mammal monitoring 

that took place during construction of 

previous components of the Tongass 

Narrows Project, a total of 322 Steller 

sea lions were observed (ADOT&PF 

2021, 2023). According to ADOT&PF, 

the average group size was 1.25 

individuals and maximum group size 

observed was five individuals. At least 

one Steller sea lion was observed during 

each month that monitoring took place. 

Monitoring during construction of the 

nearby Ward Cove Dock recorded 4.1 

individuals per day (Power Systems & 

Supplies of Alaska, 2020). 

ADOT&PF estimates that one group of 

10 Steller sea lions may be taken by 

Level B harassment each day that inwater work is planned. Based on 

ADOT&PF’s 215 days of project-related 

monitoring, NMFS finds it more 

appropriate to estimate that 1 group of 

5 Steller sea lions may be present in the 

Level B harassment zone each day (1 

group × 5 Steller sea lion × 131 

construction days = 655 takes by Level 

B harassment). 

ADOT&PF is required to implement a 

shutdown zone that exceeds the Level A 

harassment zone for Steller sea lions 

during all project activities. However, 

ADOT&PF expects that Steller sea lions 

could enter the Level A harassment 

zone undetected on rare occasions. As 

such, ADOT&PF requests take by Level 

A harassment of 5 percent of Steller sea 

lions authorized for take by Level B 

harassment. NMFS concurs that, given 

the various structures along the 

shoreline in the project area, Steller sea 

lions could enter the Level A 

harassment zone and remain in the zone 

undetected for a long enough duration 

to incur PTS before a shutdown occurs. 

However, NMFS anticipates that 5 

percent of the take by Level B 

harassment would result in an 

overestimate of Level A harassment. 

NMFS anticipates that 10 Steller sea 

lions could enter the Level A 

harassment zone and remain in the zone 

undetected for a long enough duration 

to incur PTS before a shutdown occurs 

across the 131 days of planned in-water 

work. As such, NMFS is authorizing 10 

takes by Level A harassment and 645 

takes by Level B harassment ((1 group 

× 5 individuals × 131 construction 

days)¥10 takes by Level A harassment 

= 645 takes by Level B harassment). 

Northern Elephant Seal 

Although northern elephant seals are 

known to visit the Gulf of Alaska to feed 

on benthic prey, they rarely occur on 

the beaches of Alaska. Despite the low 

probability of northern elephant seals 

entering the project area, there have 

been recent reports of elephant seals 

occurring in and near the Tongass 

Narrows, and two northern elephant 

seals were observed during ADOT&PF’s 

Tongass Narrows construction in 2022. 

As such, ADOT&PF requested take by 

Level B harassment of one elephant seal 

per 6-day work week. NMFS concurs 

that one take by Level B harassment per 

work week is appropriate. However, 

because ADOT&PF plans 7-day work 

weeks, NMFS calculates the total 

number of work weeks to occur within 

131 construction days as 19 weeks 

rather than ADOT&PF’s planned 22 

weeks (1 Northern elephant seal × 19 

work weeks = 19 takes by Level B 

harassment). 

For most project activities, the 

established shutdown zone will exceed 

the Level A harassment zone for 

Northern elephant seal. However, the 

Level A harassment zone may extend 

beyond the established shutdown zone 

for this species on 37 days (when DTH 

systems may be employed to install 24- 


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inch piles or 30-inch piles may be 

installed with an impact pile driver (200 

strikes)). While unlikely given the 

already low occurrence of Northern 

elephant seals, on those days, a 

Northern elephant seal could occur in 

the Level A harassment zone and 

remain in the zone for a long enough 

duration to incur PTS, and NMFS is 

conservatively authorizing five takes by 

Level A harassment. As such, NMFS is 

authorizing 14 takes by Level B 

harassment (1 Northern elephant seal × 

19 work weeks¥5 takes by Level A 

harassment = 14 takes by Level B 

harassment). 

Harbor Seal 

During marine mammal monitoring 

associated with ADOT&PF’s previous 

Tongass Narrows construction activities, 

550 harbor seals were observed with an 

average of 1.2 harbor seals per day and 

a maximum group size of 5. The COK 

pinnacle rock blasting project recorded 

a total of 21 harbor seal sightings of 24 

individuals over 76.2 hours of pre- and 

post-blast monitoring (Sitkiewicz 2020). 

Additionally, information from PSOs 

associated with on-going construction 

indicates that a small number of harbor 

seals are regularly sighted at about 820 

ft (250 m) from the project location 

(Wyatt, personal communication). 

Additionally, there are two key harbor 

seal haulouts about 7.1 miles (11.5 

kilometers) from the project area on a 

mid-channel island to the southeast of 

the project site. Each haulout was 

monitored in 2022 with 10 harbor seals 

observed at one haulout and 50 harbor 

seals observed at the other (Richland, 

personal communication). 

ADOT&PF estimates, and NMFS 

concurs, that up to 2 groups of 3 harbor 

seals could enter the Level B harassment 

zone per day (2 groups × 3 harbor seals 

× 131 days = 786). Further, NMFS also 

estimates that half the harbor seals 

occurring at the haulout sites within the 

project area could enter the Level B 

harassment zone on days when the 

ensonified area (during 30′′ vibratory 

pile driving) reaches these haulout sites 

(30 harbor seals × 13 days = 390). 

ADOT&PF also estimates that 1 harbor 

seal could be taken by Level A 

harassment on each day of in-water 

work (1 harbor seal × 131 days = 131 

takes by Level A harassment). For most 

project activities, the shutdown zone 

exceeds the Level A harassment zone. 

However, when an impact pile driver 

(200 strikes) is used to install 30-inch 

piles, the Level A harassment zone 

exceeds the associated shutdown zone. 

This could occur on 13 days. NMFS 

anticipates that three harbor seals could 

be taken by Level A harassment on each 

day that the Level A harassment 

isopleth for this species extends beyond 

the shutdown zone. Therefore, NMFS is 

authorizing 39 takes by Level A 

harassment (3 harbor seal × 13 days = 

39 takes by Level A harassment) and 

1,137 takes by Level B harassment (786 

takes by Level B harassment + 390 takes 

by Level B harassment ¥ 39 takes by 

Level A harassment = 1,137 takes by 

Level B harassment). 

TABLE 8—AUTHORIZED TAKE BY STOCK AND HARASSMENT TYPE AND AS A PERCENTAGE OF STOCK ABUNDANCE

Species Stock 

Authorized take Authorized take as 

a percentage of 

stock abundance Level B 

harassment 

Level A 

harassment 

Minke whale ..................................................... Alaska .............................................................. 4 0 ..............................

Fin whale ......................................................... Northeast Pacific ............................................. 2 0 0.1 

Humpback whale ............................................. Hawai1i 1 ........................................................... 128 0 1.1 

Mexico—North Pacific 1 ................................... 3 0 ..............................

Gray whale ...................................................... Eastern North Pacific ....................................... 10 0 0.04 

Pacific white-sided dolphin .............................. North Pacific .................................................... 60 0 0.2 

Killer whale ...................................................... Eastern North Pacific Alaska Resident ........... 64 0 3.3 

Eastern North Pacific Northern Resident ........ .................... .................... 21.2 

West Coast Transient ...................................... .......................................................................... .................... .................... 16.3 

Harbor porpoise ............................................... Southern Southeast Alaska Inland 2 ................ 60 15 8.4 

Dall’s porpoise ................................................. Alaska .............................................................. 90 10 0.8 

Steller sea lion ................................................. Eastern U.S ..................................................... 645 10 1.5 

Northern Elephant seal .................................... California Breeding .......................................... 14 5 <0.1 

Harbor seal ...................................................... Clarence Strait ................................................. 1,137 39 4.3 

1Given the revised stock structure for humpback whale, described in the Description of Marine Mammals in the Area of Specified Activities 

section, NMFS assumes that two percent of humpback whales occurring in Southeast Alaska are from the Mexico—North Pacific stock and the 

remaining humpback whales are from the Hawai1i stock (Wade et al., 2021). 2Given the revised stock structure described in the Description of Marine Mammals in the Area of Specified Activities section, NMFS assumed 

all the authorized takes would be of the new Southern Southeast Alaska Inland Waters stock, as that is the only stock that overlaps the project 

area. 

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. 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 


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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. 

ADOT&PF must ensure that 

construction supervisors and crews, the 

monitoring team and relevant 

ADOT&PF staff are trained prior to the 

start of all pile driving and DTH 

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. 

Protected Species Observers 

ADOT&PF must employ PSOs and 

establish monitoring locations as 

described in the NMFS-approved 

Marine Mammal Monitoring Plan and 

Section 5 of the IHA. ADOT&PF 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 

vibratory pile driving and removal, 

ADOT&PF must employ at least three 

PSOs. For all impact pile driving and 

DTH, ADOT&PF must employ at least 

two PSOs. As noted in the Changes from 

the Proposed IHA to Final IHA section, 

in the proposed IHA, NMFS proposed to 

require ADOT&PF to employ three PSOs 

for DTH activities. After publication of 

the proposed IHA, ADOT&PF requested 

for NMFS to revise this measure to 

require two PSOs for DTH activities, 

given that the zone sizes for DTH 

activities were more commensurate with 

that of impact pile driving. NMFS 

concurred, and therefore, the final IHA 

requires ADOT&PF to employ at least 

two PSOs for DTH activities, rather than 

three. The placement of the PSOs during 

all pile driving and removal and DTH 

activities will ensure that the entire 

shutdown zone is visible. 

Pre- and Post-Activity Monitoring 

Monitoring must take place from 30 

minutes prior to initiation of pile 

driving or DTH activity (i.e., preclearance monitoring) through 30 

minutes post-completion of pile driving 

or DTH 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. Further, while not 

a requirement in the IHA, the 2023 

Biological Opinion requires that if a 

work stoppage occurs and PSOs do not 

monitor the boundaries of the Level B 

harassment zone continuously during 

the work stoppage, the entire Level B 

harassment zone must be surveyed 

again for the presence of ESA-listed 

species before work may resume. 

Additionally, the 2023 Biological 

Opinion requires that in-water activities 

take place only between civil dawn and 

civil dusk when PSOs can effectively 

monitor for the presence of marine 

mammals and when the entire 

shutdown zone and adjacent waters are 

visible (e.g., monitoring effectiveness is 

not reduced due to rain, fog, snow, etc.). 

The 2023 Biological Opinion allows for 

pile driving to continue for up to 30 

minutes after sunset during evening 

civil twilight, as necessary to secure a 

pile for safety prior to demobilization 

for the evening. PSOs will continue to 

observe shutdown and monitoring zones 

during this time. The length of the postactivity monitoring period may be 

reduced if darkness precludes visibility 

of the shutdown and monitoring zones. 

Soft Start 

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. ADOT&PF 

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. 

Shutdown Zones 

For all pile driving/removal and DTH 

activities, ADOT&PF will establish 

shutdown zones (Table 9). The purpose 

of a shutdown zone is generally to 

define an area within which shutdown 

of activity will occur upon sighting of a 

marine mammal (or in anticipation of an 

animal entering the defined area). 

Shutdown zones vary based on the 

activity type and duration and marine 

mammal hearing group (Table 9). In 

most cases, shutdown zones are based 

on the estimated Level A harassment 

isopleth distances for each hearing 

group. However, in cases where 

ADOT&PF asserted that it would be 

impracticable to shut down at the Level 

A harassment isopleth due to excessive 

work stoppages, a smaller shutdown 

zone has been established (e.g., for highfrequency cetaceans and phocids during 

DTH rock socketing of 24-inch piles). 

Note that some of the established 

shutdown zones differ from those 

proposed by the ADOT&PF in their 

application (see Table 6–5 of 

ADOT&PF’s application) due to our 

incorporation of sound source levels 

and DTH TL coefficients from 

ADOT&PF’s SSV report. 

ADOT&PF anticipates that the 

maximum amount of activity within a 

given day may vary significantly (Table 

6), with large differences in maximum 

zones sizes possible (Table 7). Given 

this uncertainty and concerns related to 

ESA-listed humpback whales and fin 

whales, and practicability concerns with 

shutting down, ADOT&PF plans a tiered 

system to identify and monitor the 

appropriate Level A harassment zones 

and shutdown zones for large frequency 

cetaceans and phocids. This tiered 

system is based on the maximum 

expected number of piles to be installed 

(impact or vibratory pile driving) or the 

maximum expected DTH duration in a 

given day. At the start of each work day, 

ADOT&PF will determine the maximum 

scenario possible for that day (according 

to the defined duration intervals in 

Tables 7 and 9), which will determine 

the appropriate Level A harassment 

isopleth and associated shutdown zone 

for that day. This Level A harassment 

zone (Table 7) and associated shutdown 

zone (Table 9) must be implemented for 

the entire work day. 

The placement of PSOs during all pile 

installation and removal, and DTH 

activities (described in detail in the 

Monitoring and Reporting section) will 

ensure that the entire shutdown zones 

are visible during pile driving. 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 

(non-ESA-listed species) or 30 minutes 

(humpback whales and fin whales) have 

passed without re-detection of the 

animal. Further, pile driving activity 

must be halted upon observation of 

either 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. 

ADOT&PF must also avoid direct 

physical interaction with marine 


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mammals during construction activity. 

If a marine mammal comes within 10 m 

of such activity, operations must cease 

and vessels must reduce speed to the 

minimum level required to maintain 

steerage and safe working conditions. 

TABLE 9—SHUTDOWN ZONES AND LEVEL B HARASSMENT ZONES

Activity Pile diameter(s) 

(inches) 

Duration (min; 

vibratory/ 

DTH)/# of 

piles (impact) 

Shutdown distances (m) Level B 

harassment 

isopleth 

(m) LF MF HF PW OW 

Vibratory Installation or 

Removal, temporary 

and permanent.

30 ......................

24 or 14 .............

≤360 

≤480 

50 

40 

10 

10 

80 

60 

30 

30 

10 

10 

11,659 

7,365 

DTH (Rock Socket) ....... 24 ...................... ≤120 220 30 300 110 30 2,572 

121–180 ........................ ........................ ........................ 220 ........................ ........................

181–480 350 ........................ ........................ ........................ ........................ ........................

DTH (Tension Anchor) .. 8 ........................ ≤480 170 10 140 70 10 1,274 

Impact permanent ......... 30 ...................... 1 550 30 300 190 30 2,154 

2 ........................ ........................ ........................ 300 ........................ ........................

3 720 ........................ ........................ ........................ ........................ ........................

24 or 14 ............. 1 140 10 300 80 20 1,000 

2 290 ........................ ........................ 160 ........................ ........................

3 ........................ ........................ ........................ ........................ ........................ ........................

Impact, temporary ......... 24 or 14 ............. 1–3 120 10 140 60 10 1,000 

Based on our evaluation of the 

applicant’s planned measures, as well as 

other measures considered by NMFS, 

NMFS has determined that the required 

mitigation measures provide the means 

effecting the least practicable impact on 

the affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance. 

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 must be conducted by 

qualified, NMFS-approved PSOs, who 

will be present during all pile 

installation and removal activities, 

including vibratory, impact, and DTH 

methods, in accordance with the 

following: 

• PSOs must be independent (i.e., not 

construction personnel) and have no 

other assigned tasks during monitoring 

periods; 

• At least one PSO must have prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued IHA; 

• Other PSOs may substitute other 

relevant experience, education (degree 

in biological science or related field), or 

training for prior experience performing 

the duties of a PSO during construction 

activity pursuant to a NMFS-issued 

IHA; 

• Where a team of three or more PSOs 

is required, a lead observer or 

monitoring coordinator must be 

designated. The lead observer must have 

prior experience performing the duties 

of a PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization; and 

• PSOs must be approved by NMFS 

prior to beginning any activity subject to 

this IHA. 

PSOs should 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 of 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. 

A minimum of one PSO (the lead 

PSO) must be assigned to the active pile 

driving or DTH location to monitor the 

shutdown zones and as much of the 

harassment zones as possible. The 

observation points of the additional 


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PSOs may vary depending on the 

construction activity and location of the 

piles. During impact pile driving or 

DTH activities, the second PSO will 

select the best location to observe as 

much of the Level A harassment and 

Level B harassment zones as possible. 

To select the best observation locations 

during vibratory installation and 

removal, prior to start of construction, 

the lead PSO will stand at the 

construction site to monitor the 

shutdown zones while two or more 

PSOs travel in opposite directions from 

the project site along Tongass Narrows 

until they have reached the edge of the 

Level B harassment zone, where they 

will identify suitable observation points 

from which to observe. If visibility 

deteriorates so that the entire width of 

Tongass Narrows at the harassment zone 

boundary is not visible, 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 or fin 

whales entering or within the 

harassment zone are detected by PSOs. 

PSOs must record all observations of 

marine mammals, regardless of distance 

from the pile being driven. PSOs shall 

document any behavioral reactions in 

concert with distance from piles being 

driven or removed. 

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 of 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, vibratory or DTH), the total 

equipment duration for vibratory 

installation/removal or DTH for each 

pile or hole and 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 time of 

sighting; Time of sighting; Identification 

of the animal(s) (e.g., genus/species, 

lowest possible taxonomic level, or 

unidentified), 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 sighting (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, 

by species; 

• Detailed information about any 

implementation of any mitigation 

triggered (e.g., shutdowns and delays), a 

description of specific actions that 

ensued, and resulting changes in 

behavior of the animal(s), if any. 

ADOT&PF must also submit all PSO 

datasheets and/or raw sighting data with 

the draft report, as specified in 

condition 6(b) of this IHA. 

If no comments are received from 

NMFS within 30 days, the draft 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. 

Reporting Injured or Dead Marine 

Mammals 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, the 

IHA-holder must immediately cease the 

specified activities and report the 

incident to the Office of Protected 

Resources (OPR), NMFS and to the 

NMFS 24-hour Stranding Hotline as 

soon as feasible. If the death or injury 

was clearly caused by the specified 

activity, ADOT&PF must immediately 

cease the specified activities until 

NMFS is able to review the 

circumstances of the incident and 

determine what, if any, additional 

measures are appropriate to ensure 

compliance with the terms of the IHA. 

The IHA-holder must not resume their 

activities until notified by NMFS. The 

report must include the following 

information: 

• 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, the majority of 

our analysis applies to all the species 

listed in Table 1, given that many of the 


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anticipated effects of this project on 

different marine mammal stocks are 

expected to be relatively 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 and DTH activities 

associated with the project, as outlined 

previously, have the potential to disturb 

or displace marine mammals. 

Specifically, the specified activities may 

result in take, in the form of Level B 

harassment and, for some species Level 

A harassment, from underwater sounds 

generated by pile driving and DTH. 

Potential takes could occur if marine 

mammals are present in zones 

ensonified above the thresholds for 

Level B harassment or Level A 

harassment, identified above, while 

activities are underway. 

NMFS does not anticipate that serious 

injury or mortality will occur as a result 

of ADOT&PF’s planned activity given 

the nature of the activity, even in the 

absence of required mitigation. Further, 

no take by Level A harassment is 

anticipated for Pacific white-sided 

dolphin, killer whale, humpback whale, 

gray whale, fin whale, or minke whale, 

due to the likelihood of occurrence and/ 

or required mitigation measures. As 

stated in the mitigation section, 

ADOT&PF will implement shutdown 

zones that equal or exceed many of the 

Level A harassment isopleths shown in 

Table 9. Take by Level A harassment is 

authorized for some species (Steller sea 

lion, harbor seal, northern elephant seal, 

harbor porpoise, and Dall’s porpoise) to 

account for the potential that an animal 

could enter and remain within the area 

between a Level A harassment zone and 

the shutdown zone for a duration long 

enough to be taken by Level A 

harassment, and in some cases, to 

account for the possibility that an 

animal could enter a shutdown zone 

without detection given the various 

obstructions along the shoreline, and 

remain in the Level A harassment zone 

for a duration long enough to be taken 

by Level A harassment before being 

observed and a shutdown occurring. 

Any take by Level A harassment is 

expected to arise from, at most, a small 

degree of PTS because 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. 

Additionally, and as noted previously, 

some subset of the individuals that are 

behaviorally harassed could also 

simultaneously incur some small degree 

of TTS for a short duration of time. 

Because of the small degree anticipated, 

though, any PTS or TTS potentially 

incurred here is not expected to 

adversely impact individual fitness, let 

alone annual rates of recruitment or 

survival. 

For all species and stocks, take is 

expected to occur within a limited, 

confined area (adjacent to the project 

site) of the stock’s range. The intensity 

and duration of take by Level A 

harassment and Level B harassment will 

be minimized 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, pile removal, 

and DTH at the sites in Tongass 

Narrows 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 visually observable such as 

changes in vocalization patterns. Given 

that pile driving, pile removal, and DTH 

will occur for only a portion of the 

project’s duration and often on 

nonconsecutive days, any harassment 

would be temporary. Additionally, 

many of the species present in Tongass 

Narrows would only be present 

temporarily based on seasonal patterns 

or during transit between other habitats. 

These species would be exposed to even 

shorter periods of noise-generating 

activity, further decreasing the impacts. 

As previously described, a UME has 

been declared for gray whales. However, 

we do not expect the takes authorized 

herein to exacerbate the ongoing UME. 

No serious injury or mortality of gray 

whales is expected or authorized, and 

take by Level B harassment is limited 

(10 takes over the duration of the 

authorization). As such, the authorized 

take by Level B harassment of gray 

whale is not expected to exacerbate or 

compound upon the ongoing UME. 

For all species except humpback 

whales, there are no known BIAs near 

the project zone that will be impacted 

by ADOT&PF’s planned activities. For 

humpback whales, the inland waters of 

Southeast Alaska is a seasonal feeding 

BIA from May through September (Wild 

et al., 2023), however, the mouth of 

Tongass Narrows is a small passageway 

and represents a very small portion of 

the total available habitat. Also, while 

southeast Alaska is considered an 

important area for feeding humpback 

whales during this time, it is not 

currently designated as critical habitat 

for humpback whales (86 FR 21082, 

April 21, 2021). 

More generally, there are no known 

calving or rookery grounds within the 

project area, but anecdotal evidence 

from local experts shows that marine 

mammals are more prevalent in Tongass 

Narrows and Clarence Strait during 

spring and summer associated with 

feeding on aggregations of fish, meaning 

the area may play a role in foraging. 

Because ADOT&PF’s activities could 

occur during any season, takes may 

occur during important feeding times. 

However, the project area represents a 

small portion of available foraging 

habitat and impacts on marine mammal 

feeding for all species, including 

humpback whales, should be minimal. 

Any impacts on marine mammal prey 

that occur during ADOT&PF’s planned 

activity are expected to have, at most, 

short-term effects on foraging of 

individual marine mammals, and likely 

no effect on the populations of marine 

mammals as a whole. Indirect effects on 

marine mammal prey during the 

construction are expected to be minor, 

and these effects are unlikely to cause 

substantial effects on marine mammals 

at the individual level, with no expected 

effect on annual rates of recruitment or 

survival. 

In addition, it is unlikely that minor 

noise effects in a small, localized area of 

habitat will have any effect on the 

reproduction or survival of any 

individuals, much less the stocks’ 

annual rates of recruitment or survival. 

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 any of the 

species or stocks through effects on 

annual rates of recruitment or survival: 

• No serious injury or mortality is 

anticipated or authorized; 

• Take by Level A harassment of 

Pacific white-sided dolphin, killer 

whale, humpback whale, fin whale, gray 

whale, or minke whale is not 

anticipated or authorized; 

• ADOT&PF will implement 

mitigation measures including softstarts for impact pile driving and 

shutdown zones to minimize the 

numbers of marine mammals exposed to 


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injurious levels of sound, and to ensure 

that any take by Level A harassment is, 

at most, a small degree of PTS; 

• The intensity of anticipated takes 

by Level B harassment is relatively low 

for all stocks and will not be of a 

duration or intensity expected to result 

in impacts on reproduction or survival; 

• There are 10 known areas of 

specific biological importance, covering 

a broad area of southeast Alaska, for 

humpback whales. The project area 

overlaps a very small portion of one of 

these BIAs. No other known areas of 

particular biological importance to any 

of the affected species or stocks are 

impacted by the activity, including 

ESA-designated critical habitat; 

• The project area represents a very 

small portion of the available foraging 

area for all potentially impacted marine 

mammal species and stocks and 

anticipated habitat impacts are minor; 

and 

• Monitoring reports from similar 

work in Tongass Narrows have 

documented little to no effect on 

individuals of the same species 

impacted by the specified activities. 

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. 

The authorized number of instances 

of take is below one-third of the 

estimated stock abundance for all stocks 

(see Table 8). The number of animals 

authorized to be taken from these stocks 

would be considered small relative to 

the relevant stocks’ abundances even if 

each estimated taking occurred to a new 

individual, which is an unlikely 

scenario. Some individuals may return 

multiple times in a day, but PSOs will 

count them as separate takes if they 

cannot be individually identified. 

The Alaska stock of Dall’s porpoise 

has no official NMFS abundance 

estimate, as the most recent estimate is 

greater than 8 years old. The most recent 

estimate was 13,110 animals for just a 

portion of the stock’s range. Therefore, 

the 100 authorized takes of this stock 

clearly represent small numbers of this 

stock. 

The Mexico—North Pacific stock of 

Humpback Whale has no official NMFS 

abundance estimate, as the most recent 

estimate is greater than 8 years old. The 

most recent estimate was 571 animals 

for just a portion of the stock’s range 

(Revillagigedo Archipelago). Therefore, 

the three takes of this stock authorized 

clearly represent small numbers of this 

stock. 

There is no current or historical 

estimate of the Alaska minke whale 

stock, but there are known to be over 

1,000 minke whales in the Gulf of 

Alaska (Muto et al. 2018), so the 4 takes 

authorized is small relative to estimated 

survey abundance, even if each take 

occurred to a new individual. 

Additionally, the range of the Alaska 

stock of minke whales is extensive, 

stretching from the Canadian Pacific 

coast to the Chukchi Sea, and 

ADOT&PF’s project area will impact a 

small portion of this range. 

The best available abundance estimate 

for fin whale is not considered 

representative of the entire stock as 

surveys were limited to a small portion 

of the stock’s range, but there are known 

to be over 2,500 fin whales in the 

northeast Pacific stock (Muto et al. 

2021). As such, the two takes authorized 

is small relative to the estimated survey 

abundance, even if each 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 are 

expected to 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. 

Harbor seals are the marine mammal 

species most regularly harvested for 

subsistence by households in Ketchikan 

and Saxman (a community a few miles 

south of Ketchikan, on the Tongass 

Narrows). Eighty harbor seals were 

harvested by Ketchikan residents in 

2007, which ranked fourth among all 

communities in Alaska that year for 

harvest of harbor seals. Thirteen harbor 

seals were harvested by Saxman 

residents in 2007. In 2008, two Steller 

sea lions were harvested by Ketchikanbased subsistence hunters, but this is 

the only record of sea lion harvest by 

residents of either Ketchikan or Saxman. 

In 2012, the community of Ketchikan 

had an estimated subsistence take of 22 

harbor seals and 0 Steller sea lion (Wolf 

et al. 2013). NMFS is not aware of more 

recent data. Hunting usually occurs in 

October and November (Alaska 

Department of Fish and Game (ADF&G) 

2009), but there are also records of 

relatively high harvest in May (Wolfe et 

al. 2013). The ADF&G has not recorded 

harvest of cetaceans from Ketchikan or 

Saxman (ADF&G 2023). 

All project activities are planned to 

take place within the industrial area of 

Tongass Narrows immediately adjacent 

to Ketchikan where subsistence 

activities do not generally occur. Both 

harbor seals and Steller sea lions may be 

temporarily displaced from the project 

area. The project will also not have an 

adverse impact on the availability of 

marine mammals for subsistence use at 

locations farther away where these 

construction activities are not expected 

to take place. Some minor, short-term 

harassment of the harbor seals could 

occur, but given the information above, 

we do not expect such harassment to 

have effects on subsistence hunting 

activities. 

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, 


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NMFS has determined that there will 

not be an unmitigable adverse impact on 

subsistence uses from ADOT&PF’s 

planned 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 NMFS’ Alaska Regional 

Office (AKRO). 

NMFS is authorizing take of the 

Mexico—North Pacific stock of 

humpback whale, and fin whale, which 

are listed as threatened or endangered 

under the ESA. The NMFS AKRO 

issued a Biological Opinion under 

section 7 of the ESA on the issuance of 

an IHA to ADOT&PF under section 

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

OPR. The biological opinion concluded 

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 proposed 

actions (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 

NMFS has issued an IHA to 

ADOT&PF for the potential harassment 

of small numbers of 11 marine mammal 

species incidental to ferry berth 

construction in Tongass Narrows in 

Ketchikan, Alaska, that includes the 

previously explained mitigation, 

monitoring, and reporting requirements. 

Dated: September 11, 2023. 

Kimberly Damon-Randall, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2023–19903 Filed 9–13–23; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD340] 

Gulf of Mexico Fishery Management 

Council; Public Meeting 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice of a public meeting. 

SUMMARY: The Gulf of Mexico Fishery 

Management Council (Council) will 

hold a one-day meeting of its Reef Fish 

Advisory Panel (AP). 

DATES: The meeting will be held 

Monday, October 2, 2023, from 8:30 

a.m. to 5 p.m., EDT. 

ADDRESSES: The in-person meeting will 

take place at the Gulf Council office. 

Council address: Gulf of Mexico 

Fishery Management Council, 4107 W 

Spruce Street, Suite 200, Tampa, FL 

33607; telephone: (813) 348–1630. 

FOR FURTHER INFORMATION CONTACT: Mr. 

Ryan Rindone, Lead Fishery Biologist, 

Gulf of Mexico Fishery Management 

Council; ryan.rindone@gulfcouncil.org, 

telephone: (813) 348–1630. 

SUPPLEMENTARY INFORMATION: 

Monday, October 2, 2023; 8:30 a.m.– 

5:30 p.m., EST 

The meeting will begin with 

Introductions of Members and Adoption 

of Agenda, Approval of Minutes from 

the October 11, 2022, meeting, election 

of the Chair and Vice Chair, review the 

Scope of Work, and Reef Fish and 

Individual Fishing Quota (IFQ) Program 

Landings. 

The AP will then receive an update 

on the Marine Recreational Information 

Program—Fishing Effort Survey (MRIP– 

FES) Pilot Study and Proposed Next 

Steps, followed by a summary of the 

Gag Research Review from September 

2023 Gulf Scientific and Statistical 

Committee (SSC) Meeting. The AP will 

then review the Gag Interim Analysis 

Health Check, followed by discussions 

on the Reef Fish Framework Action: 

Modifications to Gag and Black Grouper 

Recreational Retention Limits and 

Commercial Spawning Season Closure. 

The AP will receive a brief update on 

Draft Amendment 58: Modifications to 

Shallow-water Grouper Complex 

Management Measures; and will then 

review interim analyses for Vermilion 

Snapper and Lane Snapper. 

Next, the AP will review Draft 

Snapper Grouper Amendment 44/Reef 

Fish Amendment 55: Catch Level 

Adjustments and Allocations for 

Southeastern U.S. Yellowtail Snapper, 

and then discuss the Draft Generic 

Amendment for Regulatory 

Streamlining; the AP will then receive 

Public Comment. 

Lastly, the AP will discuss any Other 

Business items. 

—Meeting Adjourns 

The meeting will also be broadcast via 

webinar. You may register for the 

webinar by visiting www.gulfcouncil.org 

and clicking on the Advisory Panel 

meeting on the calendar. The Agenda is 

subject to change, and the latest version 

along with other meeting materials will 

be posted on www.gulfcouncil.org as 

they become available. 

Although other non-emergency issues 

not on the agenda may come before the 

Advisory Panel for discussion, in 

accordance with the Magnuson-Stevens 

Fishery Conservation and Management 

Act, those issues may not be the subject 

of formal action during this meeting. 

Actions of the Advisory Panel will be 

restricted to those issues specifically 

identified in the agenda and any issues 

arising after publication of this notice 

that require emergency action under 

section 305(c) of the Magnuson-Stevens 

Fishery Conservation and Management 

Act, provided the public has been 

notified of the Council’s intent to take 

action to address the emergency. 

Special Accommodations 

The meeting is physically accessible 

to people with disabilities. Requests for 

sign language interpretation or other 

auxiliary aid should be directed to 

Kathy Pereira, (813) 348–1630, at least 

5 days prior to the meeting date. 

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

Dated: September 11, 2023. 

Diane M. DeJames-Daly, 

Acting Deputy Director, Office of Sustainable 

Fisheries, National Marine Fisheries Service. 

[FR Doc. 2023–19930 Filed 9–13–23; 8:45 am] 

BILLING CODE 3510–22–P 


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