1884 Federal Register / Vol. 89, No. 8 / Thursday, January 11, 2024 / Notices 

2The specific exclusion for Lee Kum Kee’s 

shrimp sauce applies only to the scope of the AD 

order on certain frozen warmwater shrimp from 

China. 

3On April 26, 2011, Commerce amended the 

orders to include dusted shrimp, pursuant to the 

Court decision in Ad Hoc Shrimp Trade Action 

Committee v. United States, 703 F. Supp. 2d 1330 

(CIT 2010) and the U.S. International Trade 

Commission determination, which found the 

domestic like product to include dusted shrimp. 

See Certain Frozen Warmwater Shrimp from Brazil, 

India, the People’s Republic of China, Thailand, 

and the Socialist Republic of Vietnam: Amended 

Antidumping Duty Orders in Accordance with Final 

Court Decision, 76 FR 23277 (April 26, 2011); see 

also Frozen Warmwater Shrimp from Brazil, China, 

India, Thailand, and Vietnam, Inv. Nos. 731– 

TA1063, 1064, 1066–1068 (Review), USITC Pub. 

4221 (March 2011). 

4See Certain Frozen Warmwater Shrimp from the 

People’s Republic of China, India, Thailand, and 

the Socialist Republic of Vietnam: Continuation of 

Antidumping Duty Orders, 88 FR 42914 (July 5, 

2023). 

Frozen shrimp and prawns that are 

packed with marinade, spices or sauce 

are included in the scope of the orders. 

In addition, food preparations, which 

are not ‘‘prepared meals,’’ that contain 

more than 20 percent by weight of 

shrimp or prawn are also included in 

the scope of the orders. 

Excluded from the scope are: (1) 

breaded shrimp and prawns (HTSUS 

subheading 1605.20.1020); (2) shrimp 

and prawns generally classified in the 

Pandalidae family and commonly 

referred to as coldwater shrimp, in any 

state of processing; (3) fresh shrimp and 

prawns whether shell on or peeled 

(HTSUS subheadings 0306.23.0020 and 

0306.23.0040); (4) shrimp and prawns in 

prepared meals (HTSUS subheading 

1605.20.0510); (5) dried shrimp and 

prawns; (6) Lee Kum Kee’s shrimp 

sauce; 2 (7) canned warmwater shrimp 

and prawns (HTSUS subheading 

1605.20.1040); and (8) certain battered 

shrimp. Battered shrimp is a shrimpbased product: (1) that is produced from 

fresh (or thawed-from-frozen) and 

peeled shrimp; (2) to which a ‘‘dusting’’ 

layer of rice or wheat flour of at least 95 

percent purity has been applied; (3) 

with the entire surface of the shrimp 

flesh thoroughly and evenly coated with 

the flour; (4) with the non-shrimp 

content of the end product constituting 

between four and 10 percent of the 

product’s total weight after being 

dusted, but prior to being frozen; and (5) 

that is subjected to individually quick 

frozen (‘‘IQF’’) freezing immediately 

after application of the dusting layer. 

When dusted in accordance with the 

definition of dusting above, the battered 

shrimp product is also coated with a 

wet viscous layer containing egg and/or 

milk, and par-fried. 

The products covered by the orders 

are currently classified under the 

following HTSUS subheadings: 

0306.17.00.03, 0306.17.00.06, 

0306.17.00.09, 0306.17.00.12, 

0306.17.00.15, 0306.17.00.18, 

0306.17.00.21, 0306.17.00.24, 

0306.17.00.27, 0306.17.00.40, 

1605.21.10.30, 1605.29.10.10, 

0306.17.0004, 0306.17.0005, 

0306.17.0007, 0306.17.0008, 

0306.17.0010, 0306.17.0011, 

0306.17.0013, 0306.17.0014, 

0306.17.0016, 0306.17.0017, 

0306.17.0019, 0306.17.0020, 

0306.17.0022, 0306.17.0023, 

0306.17.0025, 0306.17.0026, 

0306.17.0028, 0306.17.0029, 

0306.17.0041, 0306.17.0042. These 

HTSUS subheadings are provided for 

convenience and for customs purposes 

only; the written description of the 

scope of the orders are dispositive.3 ’’ 

Background 

On July 5, 2023, Commerce published 

in the Federal Register the continuation 

of the orders for certain frozen 

warmwater shrimp from China, India, 

Thailand, and Vietnam.4 We 

inadvertently included the wrong scope 

of the orders. 

Notification to Interested Parties 

This notice is issued and published in 

accordance with sections 751(c), 

751(d)(2), and 777(i) of the Tariff Act of 

1930, as amended, and 19 CFR 

351.218(f)(4). 

Dated: January 5, 2024. 

Abdelali Elouaradia, 

Deputy Assistant Secretary for Enforcement 

and Compliance. 

[FR Doc. 2024–00396 Filed 1–10–24; 8:45 am] 

BILLING CODE 3510–DS–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD574] 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Sitka Seaplane 

Base Construction 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorizations; request for 

comments on proposed authorizations 

and possible renewals. 

SUMMARY: NMFS has received a request 

from the City and Borough of Sitka 

(CBS) for authorization to take marine 

mammals incidental to Sitka seaplane 

base construction activities over two 

years in Sitka, Alaska. Pursuant to the 

Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue two incidental 

harassment authorizations (IHA) to 

incidentally take marine mammals 

during the specified activities. NMFS is 

also requesting comments on possible 

one-time, 1-year renewals for each IHA 

that could be issued under certain 

circumstances and if all requirements 

are met, as described in Request for 

Public Comments at the end of this 

notice. NMFS will consider public 

comments prior to making any final 

decision on the issuance of the 

requested MMPA authorizations and 

agency responses will be summarized in 

the final notice of our decision. 

DATES: Comments and information must 

be received no later than February 12, 

2024. 

ADDRESSES: Comments should be 

addressed to Jolie Harrison, Chief, 

Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service and should be 

submitted via email to ITP.harlacher@

noaa.gov. 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-mammalprotection/incidental-takeauthorizations-construction-activities. 

In case of problems accessing these 

documents, please call the contact listed 

above. 

Instructions: NMFS is not responsible 

for comments sent by any other method, 

to any other address or individual, or 

received after the end of the comment 

period. Comments, including all 

attachments, must not exceed a 25- 

megabyte file size. All comments 

received are a part of the public record 

and will generally be posted online at 

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

national/marine-mammal-protection/ 

incidental-take-authorizationsconstruction-activities without change. 

All personal identifying information 

(e.g., name, address) voluntarily 

submitted by the commenter may be 

publicly accessible. Do not submit 

confidential business information or 

otherwise sensitive or protected 

information. 

FOR FURTHER INFORMATION CONTACT: 

Jenna Harlacher, Office of Protected 

Resources, NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 


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Federal Register / Vol. 89, No. 8 / Thursday, January 11, 2024 / Notices 1885 

Background 

The MMPA prohibits the ‘‘take’’ of 

marine mammals, with certain 

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

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

seq.) direct the Secretary of Commerce 

(as delegated to NMFS) to allow, upon 

request, the incidental, but not 

intentional, taking of small numbers of 

marine mammals by U.S. citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

proposed or, if the taking is limited to 

harassment, a notice of a proposed IHA 

is provided to the public for review. 

Authorization for incidental takings 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s) and will not have 

an unmitigable adverse impact on the 

availability of the species or stock(s) for 

taking for subsistence uses (where 

relevant). Further, NMFS must prescribe 

the permissible methods of taking and 

other ‘‘means of effecting the least 

practicable adverse impact’’ on the 

affected species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance, and on the 

availability of the species or stocks for 

taking for certain subsistence uses 

(referred to in shorthand as 

‘‘mitigation’’); and requirements 

pertaining to the mitigation, monitoring 

and reporting of the takings are set forth. 

The definitions of all applicable MMPA 

statutory terms cited above are included 

in the relevant sections below. 

National Environmental Policy Act 

To comply with the National 

Environmental Policy Act of 1969 

(NEPA; 42 U.S.C. 4321 et seq.) and 

NOAA Administrative Order (NAO) 

216–6A, NMFS must review our 

proposed action (i.e., the issuance of an 

IHA) with respect to potential impacts 

on the human environment. 

This action is consistent with 

categories of activities identified in 

Categorical Exclusion B4 (IHAs with no 

anticipated serious injury or mortality) 

of the Companion Manual for NAO 216– 

6A, which do not individually or 

cumulatively have the potential for 

significant impacts on the quality of the 

human environment and for which we 

have not identified any extraordinary 

circumstances that would preclude this 

categorical exclusion. Accordingly, 

NMFS has preliminarily determined 

that the issuance of the proposed IHA 

qualifies to be categorically excluded 

from further NEPA review. We will 

review all comments submitted in 

response to this notice prior to 

concluding our NEPA process or making 

a final decision on the IHA request. 

Summary of Request 

On September 1, 2023, NMFS 

received a request from CBS for two 

IHAs to take marine mammals 

incidental to the Sitka seaplane base 

construction project in Sitka, Alaska, 

over the course of two years. Following 

NMFS’ review of the application and a 

revised version, CBS submitted a final 

version on November 15, 2023. The 

application was deemed adequate and 

complete on December 1, 2023. For both 

IHAs, CBS’s request is for take of seven 

species of marine mammals by Level B 

harassment and, for a subset of three of 

these species, Level A harassment. 

Neither CBS nor NMFS expect serious 

injury or mortality to result from this 

activity and, therefore, IHAs are 

appropriate. 

Description of Proposed Activity 

Overview 

CBS proposes to replace the existing 

seaplane base in the Sitka Channel in 

Sitka, Alaska. The purpose of this 

project is to construct a new seaplane 

base, which would address existing 

capacity, safety, and condition 

deficiencies for critical seaplane 

operations, and for all seaplanes to 

transit the Sitka Chanel more safely. The 

proposed location of the new seaplane 

base in the Sitka Channel is located on 

the northern shore of Japonski Island in 

the Sitka Sound. Over the course of 2 

years spanning July 2024–June 2025 and 

July 2025–June 2026, CBS would use a 

variety of methods, including vibratory 

and impact pile driving, and down-thehole (DTH) drilling to install and 

remove piles. These methods of pile 

driving would introduce underwater 

sounds that may result in take, by Level 

A and Level B harassment, of marine 

mammals. 

Dates and Duration 

CBS anticipates that the seaplane base 

construction project would occur over 2 

years (phases). The in-water work 

window would last from July 2024 to 

June 2025 (Phase I) and July 2025 to 

June 2026 (Phase II). Pile driving and 

removal activities are anticipated to take 

45 hours over 31 days in Phase I and 13 

hours over 9 days in Phase II. All inwater pile driving would be completed 

during daylight hours. The Phase I IHA 

would be valid from July 1, 2024 to June 

30, 2025, and the Phase II IHA would be 

valid from July 1, 2025 to June 30, 2026. 

Specific Geographic Region 

The CBS seaplane base is located on 

the northern shore of Japonski Island in 

the Sitka Channel. Sitka Channel 

separates Japonski Island from Sitka 

Harbor and downtown Sitka on the 

much larger Baranof Island. The Sitka 

Channel is located on the eastern shore 

of Sitka Sound, west of Crescent Bay 

and adjacent to Whiting Harbor. Sitka 

Channel is bookended by the Channel 

Rock Breakwaters to the north and 

James O’Connell Bridge to the south. 

Sitka Channel is approximately 150 feet 

(ft) (46 meters (m)) wide and about 22 

ft (6.7 m) deep at its narrowest. 


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1886 Federal Register / Vol. 89, No. 8 / Thursday, January 11, 2024 / Notices 

Figure 1—Project Location 

Detailed Description of the Specified 

Activity 

The purpose of the proposed project 

is to replace the existing seaplane base 

in Sitka that has come to the end of its 

useful life and has several shortcomings, 

including limited docking capacity. The 

existing facility is expensive to 

maintain, has wildlife conflicts with a 

nearby seafood processing plant, and 

requires pilots to navigate a busy 

channel with heavy ship traffic. The 

new seaplane base would improve 

safety of seaplane operations by 

reducing traffic and congestion in Sitka 

Channel. The proposed project would 

consist of several components including 

in-water and landside construction, 

completed over two phases. All 

components of landside construction 

would not cause harassment of marine 

mammals and are not discussed further. 

Phase I would involve the installation 

and removal of temporary piles, and the 

installation of permanent piles. During 

Phase I, 10 16-inch (in, 0.4 m) and 16 

24-in (0.6 m) permanent steel piles 

would be installed. The installation and 

removal of 12 temporary 16-in (0.4 m) 

steel pipe piles would be completed to 

support permanent pile installation. 

Vibratory hammers, impact hammers, 

and DTH drilling would be used for the 

installation and removal of the piles 

(table 1). The installation and removal 

of temporary piles would be conducted 

using impact and vibratory hammers. 

All permanent piles would be initially 

installed with a vibratory hammer. After 

vibratory driving, piles would be 

socketed into the bedrock with DTH 

drilling equipment. Finally, piles would 

be driven the final few inches of 

embedment with an impact hammer. 

Phase II similarly would involve the 

installation and removal of temporary 

piles, and the installation of permanent 

piles. During Phase II six 24-in (0.6 m) 

steel piles would be installed. The 

installation and removal of six 

temporary 16-in (0.4 m) steel pipe piles 

would be completed to support the 

permanent pile installation. As in Phase 

I, vibratory hammers, impact hammers, 

and DTH drilling would be used for the 

installation and removal of the piles 

(table 2). The installation and removal 

of temporary piles would be conducted 

using impact and vibratory hammers. 

All permanent piles would be initially 

installed with a vibratory hammer. After 

vibratory driving, piles would be 

socketed into the bedrock with DTH 

drilling equipment. Finally, piles would 

be driven the final few inches of 

embedment with an impact hammer. 

TABLE 1—PHASE 1 PROJECT PILE INSTALLATION AND REMOVAL SUMMARY

Project component Temp install 

(16-in) 

Temp remove 

(16-in) 

Perm install 

(16-in) 

Perm Install 

(24-in) 

Total # of piles ................................................................................................. 12 12 10 16 

Vibratory Pile Driving 

Max # of piles/day ........................................................................................... 6 6 6 6 

Time/pile (minutes) .......................................................................................... 10 10 10 10 

Time/day (min) ................................................................................................. 60 60 60 60 


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Federal Register / Vol. 89, No. 8 / Thursday, January 11, 2024 / Notices 1887 

TABLE 1—PHASE 1 PROJECT PILE INSTALLATION AND REMOVAL SUMMARY—Continued 

Project component Temp install 

(16-in) 

Temp remove 

(16-in) 

Perm install 

(16-in) 

Perm Install 

(24-in) 

# of days .......................................................................................................... 2 2 1.7 2.7 

Total # of hours ............................................................................................... 2 2 1.7 2.7 

DTH Drilling 

Max # of piles/day ........................................................................................... ........................ ........................ 2 2 

strikes/pile ........................................................................................................ ........................ ........................ 36,000 54,000 

strikes/sec ........................................................................................................ ........................ ........................ 10 10 

time/pile ............................................................................................................ ........................ ........................ 60 90 

time/day (min) .................................................................................................. ........................ ........................ 120 180 

# of days .......................................................................................................... ........................ ........................ 5 8 

Total # of hours ............................................................................................... ........................ ........................ 10 24 

Impact Pile Driving 

Max # of piles/day ........................................................................................... 4 ........................ 4 4 

strikes/pile ........................................................................................................ 175 ........................ 175 175 

time/pile (min) .................................................................................................. 5 ........................ 5 5 

time/day (min) .................................................................................................. 20 ........................ 20 20 

# of days .......................................................................................................... 3 ........................ 2.5 4 

Total # of hours ............................................................................................... 1 ........................ 0.8 1.3 

TABLE 2—PHASE 2 PROJECT PILE INSTALLATION AND REMOVAL SUMMARY

Project component Temp install 

(16-in) 

Temp remove 

(16-in) 

Perm install 

(24-in) 

Total # of piles ............................................................................................................................. 6 6 6 

Vibratory Pile Driving 

Max # of piles/day ....................................................................................................................... 6 6 6 

Time/pile (minutes) ...................................................................................................................... 10 10 10 

Time/day (min) ............................................................................................................................. 60 60 60 

# of days ...................................................................................................................................... 1 1 1 

Total # of hours ........................................................................................................................... 1 1 1 

DTH Drilling 

Max # of piles/day ....................................................................................................................... ........................ ........................ 2 

strikes/pile .................................................................................................................................... ........................ ........................ 54,000 

strikes/sec .................................................................................................................................... ........................ ........................ 10 

time/pile ........................................................................................................................................ ........................ ........................ 90 

time/day (min) .............................................................................................................................. ........................ ........................ 180 

# of days ...................................................................................................................................... ........................ ........................ 3 

Total # of hours ........................................................................................................................... ........................ ........................ 9 

Impact Pile Driving 

Max # of piles/day ....................................................................................................................... 4 ........................ 4 

strikes/pile .................................................................................................................................... 175 ........................ 175 

time/pile (min) .............................................................................................................................. 5 ........................ 5 

time/day (min) .............................................................................................................................. 20 ........................ 20 

# of days ...................................................................................................................................... 1.5 ........................ 1.5 

Total # of hours ........................................................................................................................... 0.5 ........................ 0.5 

Additionally, this project would 

include in-water work that is not 

expected to result in take of marine 

mammals. During Phase I and II, CBS 

proposed to discharge fill below the 

high tide line. The excavated materials 

from above the high tide line would be 

placed below the high tide line to 

develop the seaplane base uplands. The 

fill would be placed using an excavator 

and dozer and then compacted using a 

vibratory soil compactor. The total area 

of placement of fill below the high tide 

line in Phase I would be 1.6 acres (6,475 

square meters (m2)) and in Phase II 

would be 1.3 acres (5,261 m2). While 

marine mammals may behaviorally 

respond in some small degree to the 

noise generated by the placement of fill 

operations, given the slow, predictable 

movements of the equipment, and 

absent any other contextual features that 

would cause enhanced concern, NMFS 

does not expect CBS’s planned 

placement of fill to result in the take of 

marine mammals and it is not discussed 

further. 

Proposed mitigation, monitoring, and 

reporting measures are described in 

detail later in this document (please see 

Proposed Mitigation and Proposed 

Monitoring and Reporting). 


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Description of Marine Mammals in the 

Area of Specified Activities 

Sections 3 and 4 of the application 

summarize available information 

regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history of the potentially 

affected species. NMFS fully considered 

all of this information, and we refer the 

reader to these descriptions, instead of 

reprinting the information. Additional 

information regarding population trends 

and threats may be found in NMFS’ 

Stock Assessment Reports (SARs; 

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

national/marine-mammal-protection/ 

marine-mammal-stock-assessments) 

and more general information about 

these species (e.g., physical and 

behavioral descriptions) may be found 

on NMFS’ website (https://

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

Table 3 lists all species or stocks for 

which take is expected and proposed to 

be authorized for this activity and 

summarizes information related to the 

population or stock, including 

regulatory status under the MMPA and 

Endangered Species Act (ESA) and 

potential biological removal (PBR), 

where known. PBR is defined by the 

MMPA as the maximum number of 

animals, not including natural 

mortalities, that may be removed from a 

marine mammal stock while allowing 

that stock to reach or maintain its 

optimum sustainable population (as 

described in NMFS’ SARs). While no 

serious injury or mortality is anticipated 

or proposed to be authorized here, PBR 

and annual serious injury and mortality 

from anthropogenic sources are 

included here as gross indicators of the 

status of the species or stocks and other 

threats. 

Marine mammal abundance estimates 

presented in this document represent 

the total number of individuals that 

make up a given stock or the total 

number estimated within a particular 

study or survey area. NMFS’ stock 

abundance estimates for most species 

represent the total estimate of 

individuals within the geographic area, 

if known, that comprises that stock. For 

some species, this geographic area may 

extend beyond U.S. waters. All managed 

stocks in this region are assessed in 

NMFS’ 2022 U.S. Alaska SAR. All 

values presented in table 3 are the most 

recent available at the time of 

publication and are available online at: 

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

national/marine-mammal-protection/ 

marine-mammal-stock-assessments. 

TABLE 3—SPECIES LIKELY IMPACTED BY THE SPECIFIED ACTIVITIES

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 1

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 2

PBR Annual 

M/SI 3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) 

Family Balaenopteridae 

(rorquals): 

Humpback Whale ............... Megaptera novaeangliae .......... Hawai1i ...................................... -,-,N 11,278 (0.56, 7,265, 

2020).

127 27 

Mexico-North Pacific ................. T,D,Y N/A (N/A, N/A, 2006) ...... UND 0.6 

Minke Whale ....................... Balaenoptera acutorostrata ...... Alaska ....................................... -,-,N N/A (N/A, N/A, 2018) ...... ................ 0 

Family Eschrichtiidae: 

Gray Whale ......................... Eschrichtius robustus ................ Eastern North Pacific ................ -,-,N 26,960 (0.05, 25,849, 

2016).

801 131 

Superfamily Odontoceti (toothed whales, dolphins, and porpoises) 

Family Delphinidae: 

Killer whale ......................... Orca orcinus ............................. Northern Resident ..................... -,-,N 302 (N/A, 302, 2018) ...... 2.2 0.2 

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

Gulf of Alaska/Aleutian Islands/ 

Bering Sea Transient.

-,-,N 587 (N/A, 587, 2012) ...... 5.9 0.8 

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

Family Phocoenidae (porpoises): 

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

Order Carnivora—Superfamily Pinnipedia 

Family Otariidae (eared seals 

and sea lions): 

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

2019).

318 254 

Eastern Stock ........................... -,-,N 43,201 (N/A, 43,201, 

2017).

2,592 112 

Family Phocidae (earless seals): 

Harbor seal ......................... Phoca vituline richardii .............. Sitka/Chatham .......................... -,-,N 13,289 (N/A, 11,883, 

2015).

356 77 

1Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the 

ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or 

which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically 

designated under the MMPA as depleted and as a strategic stock. 2 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessmentreports CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 3These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. 

As indicated above, all 7 species (with 

12 managed stocks) in table 3 

temporally and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur. All species 

that could potentially occur in the 

proposed action area are included in 

table 8 of the IHA application. While 

northern fur seal, Pacific white-sided 


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Federal Register / Vol. 89, No. 8 / Thursday, January 11, 2024 / Notices 1889 

dolphin, Dall’s porpoise, North Pacific 

right whale, sperm whale, fin whale, 

and Cuvier’s beaked whale have been 

documented in or near Sitka Sound and 

Sitka Channel, the temporal and/or 

spatial occurrence of these species is 

such that take is not expected to occur, 

and they are not discussed further 

beyond the explanation provided here. 

These species are all considered to be 

rare (no sightings in recent years) or 

very rare (no local knowledge of 

sightings within the project vicinity) 

within Sitka Sound or near the action 

area. The take of these species has not 

been requested nor is proposed to be 

authorized and these species are not 

considered further in this document. In 

addition to what is included in Sections 

3 and 4 of the application, the SARs, 

and NMFS’ website, further localized 

data and detail informing the baseline 

for select species (i.e., information 

regarding current Unusual Mortality 

Events (UME) and important habitat 

areas) is provided below. 

Additionally, the Northern Sea Otter 

may be found in Sitka Sound. However, 

the Northern Sea Otter are managed by 

the U.S. Fish and Wildlife Service and 

are not considered further in this 

document. 

Gray Whale 

The migration pattern of gray whales 

appears to follow a route along the 

western coast of Southeast Alaska, 

traveling northward from British 

Columbia through Hecate Strait and 

Dixon Entrance, passing the west coast 

of Baranof Island from late March to 

May and then return south in October 

and November (Jones et al. 1984, Ford 

et al. 2013). The project area is inside 

Sitka Sound on the northern shore of 

Japonski Island, adjacent to Baranof 

Island. 

During 190 hours of observation from 

1994 to 2002 from Sitka’s Whale Park, 

three gray whales were observed 

(Straley et al., 2017). During recent 

marine mammal surveys conducted in 

the vicinity of the project action area, no 

gray whales were sighted, and these 

species are not known or expected to 

occur near or within Sitka Channel 

(Windward 2017; Turnagain 2017; 

Straley et al., 2017; Turnagain 2018; 

SolsticeAK 2019; SolsticeAK 2020; 

Halibut Point Marine Services 2021; 

SolsticeAK 2022). However, Sitka 

Sound is within a gray whale migratory 

route Biologically Important Area (BIA) 

(March–May; November–January) and a 

feeding BIA (March–June) (Wild et al., 

2023). 

Since January 1, 2019, elevated gray 

whale strandings have occurred along 

the west coast of North America from 

Mexico through Alaska. This event has 

been declared an UME, though a cause 

has not yet been determined. More 

information is available at https://

www.fisheries.noaa.gov/national/ 

marine-life-distress/active-and-closedunusual-mortality-events. 

Humpback Whale 

Humpback whales are the most 

commonly observed baleen whale in 

Sitka Sound. They have been observed 

in Southeast Alaska in all months of the 

year (Baker et al. 1985, 1986), although 

they are most common in Sitka Sound’s 

Eastern Channel in November, 

December, and January (Straley et al., 

2017). In late fall and winter, herring 

sometimes overwinter in deep fjords in 

Silver Bay and Eastern Channel, and 

humpback whales aggregate in these 

areas to feed on them. In the summer 

when prey is dispersed throughout Sitka 

Sound, humpback whales also disperse 

throughout the Sound (Straley et al., 

2017). 

Humpback whales have been 

frequently observed during construction 

projects in Sitka Sound, including the 

Biorka Island Dock Replacement Project 

(Turnagain Marine Construction, 2018) 

and the Sitka GPIP Multipurpose Dock 

Project (Turnagain Marine Construction, 

2017). During 190 hours of observation 

from 1994 to 2002 from Sitka’s Whale 

Park, 440 humpback whales were 

observed (Straley et al., 2017). During 

21 days of monitoring during the 

construction of GPIP Dock between 

October 9 and November 9, 2017, 39 

humpback whales were observed 

(Turnagain 2017). No humpback whales 

were observed within Sitka Channel 

during the eight days of monitoring in 

January 2017 during the construction of 

the Sitka Petro Dock (Windward 2017). 

Near Biorka Island, about 25 kilometers 

south of the project, humpback whales 

were sighted in June (22 whales), July (3 

whales), and September (2 whales) 2018 

(Turnagain 2018). No whales were 

sighted in August during the Biorka 

Island monitoring effort. Humpback 

whales were not observed during recent 

monitoring conducted for short periods 

over 8 days in September 2018 within 

a 400-meter radius surrounding the 

O’Connell Bridge Lightering Float 

(SolsticeAK 2019). During 39 days of 

monitoring in January through March 

2020 for the Crescent Harbor Float 

Rebuild Project, no humpbacks were 

observed. Humpback whales were not 

observed in the project area during 5 

days of monitoring in March 2022 

during the geotechnical survey for this 

project (SolsticeAK 2022). 

Given their widespread range and 

their opportunistic foraging strategies, 

humpback whales may be in Sitka 

Sound year-round but are more likely to 

occur in the summer months, although 

they are not as frequent in the action 

area. 

According to Wade et al. (2016), 

humpback whales in Southeast Alaska 

are most likely to be from the Hawaii 

DPS (distinct population segment, 98 

percent probability), with a 2 percent 

probability of being from the threatened 

Mexico DPS. Sitka Sound is within 

seasonal humpback whale feeding BIAs 

from March–May and September– 

December (Wild et al., 2023). 

Steller Sea Lion 

Steller sea lions occur year-round in 

the project area. Most are expected to be 

from the Eastern DPS; however, it is 

likely that some Steller sea lions in the 

action area are from the endangered 

Western DPS (Jemison et al. 2013; 

NMFS 2013). Jemison et al. (2013) 

estimated an average annual breeding 

season movement of 917 Western DPS 

Steller sea lions to Southeast Alaska. 

Based on surveys and analysis 

conducted by Hastings et al. (2020), an 

estimated 2.2 percent of Steller sea lions 

in the vicinity of the project are Western 

DPS Steller sea lions. 

Critical habitat has been defined in 

Southeast Alaska at major haulouts and 

major rookeries (50 CFR 226.202), but 

the project action area does not overlap 

with Steller sea lion critical habitat. The 

Biorka Island haulout is the closest 

designated critical habitat and is 

approximately 25 kilometers southwest 

of the project area. 

Based on Straley et al. (2017) and 

other vessel-based surveys conducted 

from 1994 to 2016, Steller sea lion 

numbers are highest near the project 

area in January and February. January 

was the most abundant month with 

about 190 Steller sea lions spotted. 

February and November were next with 

about 170 and 120 Steller sea lions 

spotted, respectively. The fewest Steller 

sea lions were spotted in the month of 

May (1995–2002). 

Individual sea lions were seen on 19 

of 21 days in Silver Bay and Easter 

Channel during monitoring for GPIP 

dock construction between October and 

November 2017 (Turnagain 2017). Near 

Biorka Island, sea lions were seen 

infrequently; sea lions were sighted in 

June (six animals), July (two animals), 

and no sea lions were seen in August 

2018 (Turnagain 2018). During 8 days of 

monitoring in January 2017 for the Petro 

Marine dock, about 1.6 kilometers (1 

mile) southwest of the Sitka SPB, 

individual sea lions were seen on 3 days 

(Windward 2017). Steller sea lions were 

observed 5 of 8 days during monitoring 


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conducted for 15-minute periods in 

September 2018 for the O’Connell 

Bridge Lightering Float (SolsticeAK 

2019). During in-water construction 

work for the O’Connell Bridge 

Lightering Float Pile Replacement 

Project between June 9 and June 12, 

2019, 42 Steller sea lions were sighted 

(SolsticeAK 2019). During 39 days of 

marine mammal monitoring for the 

Crescent Harbor Float Replacement 

Project in January and February 2020, 

six sea lions were observed southwest of 

Sitka Channel (SolsticeAK 2020). Steller 

sea lions were most often observed 

alone or in small groups of 2 or 3 during 

these monitoring efforts; however, a 

group of more than 100 was sighted on 

at least 1 occasion (Straley et al. 2017; 

Windward 2017; SolsticeAK 2019; 

SolsticeAK 2020). During the original 

construction of the Halibut Point Marine 

Services dock facility, no Steller sea 

lions were recorded within the 200- 

meter shutdown zone during pile 

driving operations; however, observers 

indicated observing individual sea lions 

outside the 200-meter zone four to five 

times per week (McGraw, 2019). 

During the summer months, sea lions 

are seen in the project area daily. Two 

to three individual sea lions feed on fish 

carcasses dumped adjacent to the 

project site from fishing charter 

operations in a nearby private marina. 

However, during the fall and winter, the 

charter fishing operations are not 

underway and the sea lions are not as 

active in the area (McGraw, pers. com., 

2019). 

Marine Mammal Hearing 

Hearing is the most important sensory 

modality for marine mammals 

underwater, and exposure to 

anthropogenic sound can have 

deleterious effects. To appropriately 

assess the potential effects of exposure 

to sound, it is necessary to understand 

the frequency ranges marine mammals 

are able to hear. Not all marine mammal 

species have equal hearing capabilities 

(e.g., Richardson et al., 1995; Wartzok 

and Ketten, 1999; Au and Hastings, 

2008). To reflect this, Southall et al. 

(2007, 2019) recommended that marine 

mammals be divided into hearing 

groups based on directly measured 

(behavioral or auditory evoked potential 

techniques) or estimated hearing ranges 

(behavioral response data, anatomical 

modeling, etc.). Note that no direct 

measurements of hearing ability have 

been successfully completed for 

mysticetes (i.e., low-frequency 

cetaceans). Subsequently, NMFS (2018) 

described generalized hearing ranges for 

these marine mammal hearing groups. 

Generalized hearing ranges were chosen 

based on the approximately 65 decibel 

(dB) threshold from the normalized 

composite audiograms, with the 

exception for lower limits for 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 4. 

TABLE 4—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 

This section provides a discussion of 

the ways in which components of the 

specified activity may impact marine 

mammals and their habitat. The 

Estimated Take of Marine Mammals 

section later in this document includes 

a quantitative analysis of the number of 

individuals that are expected to be taken 

by this activity. The Negligible Impact 

Analysis and Determination section 

considers the content of this section, the 

Estimated Take of Marine Mammals 

section, and the Proposed Mitigation 

section, to draw conclusions regarding 

the likely impacts of these activities on 

the reproductive success or survivorship 

of individuals and whether those 

impacts are reasonably expected to, or 

reasonably likely to, adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival. 

Description of Sound Sources 

The marine soundscape is comprised 

of both ambient and anthropogenic 

sounds. Ambient sound is defined as 

the all-encompassing sound in a given 

place and is usually a composite of 

sound from many sources both near and 

far. The sound level of an area is 

defined by the total acoustical energy 

being generated by known and 

unknown sources. These sources may 

include physical (e.g., waves, wind, 

precipitation, earthquakes, ice, 

atmospheric sound), biological (e.g., 

sounds produced by marine mammals, 

fish, and invertebrates), and 

anthropogenic sound (e.g., vessels, 

dredging, aircraft, construction). 

The sum of the various natural and 

anthropogenic sound sources at any 

given location and time—which 

comprise ‘‘ambient’’ or ‘‘background’’ 

sound—depends not only on the source 

levels (as determined by current 

weather conditions and levels of 

biological and shipping activity) but 

also on the ability of sound to propagate 

through the environment. In turn, sound 

propagation is dependent on the 

spatially and temporally varying 

properties of the water column and sea 

floor, and is frequency-dependent. As a 

result of the dependence on a large 

number of varying factors, ambient 

sound levels can be expected to vary 

widely over both coarse and fine spatial 

and temporal scales. Sound levels at a 


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given frequency and location can vary 

by 10–20 dB from day to day 

(Richardson et al., 1995). The result is 

that, depending on the source type and 

its intensity, sound from the specified 

activity may be a negligible addition to 

the local environment or could form a 

distinctive signal that may affect marine 

mammals. 

In-water construction activities 

associated with the project would 

include impact and vibratory pile 

driving and DTH drilling. The sounds 

produced by these activities fall into 

one of two general sound types: 

impulsive and non-impulsive. 

Impulsive sounds (e.g., explosions, 

gunshots, sonic booms, impact pile 

driving) are typically transient, brief 

(less than 1 second), broadband, and 

consist of high peak sound pressure 

with rapid rise time and rapid decay 

(American National Standards Institute 

(ANSI) 1986; National Institute for 

Occupational Safety and Health 

(NIOSH) 1998; ANSI 2005; NMFS 

2018a). Non-impulsive sounds (e.g., 

aircraft, machinery operations such as 

drilling or dredging, vibratory pile 

driving, and active sonar systems) can 

be broadband, narrowband or tonal, 

brief or prolonged (continuous or 

intermittent), and typically do not have 

the high peak sound pressure with raid 

rise/decay time that impulsive sounds 

do (ANSI 1995; NIOSH 1998; NMFS 

2018a). The distinction between these 

two sound types is important because 

they have differing potential to cause 

physical effects, particularly with regard 

to hearing (e.g., Ward 1997 in Southall 

et al., 2007). 

Three types of hammers would be 

used on this project: impact, vibratory, 

and DTH. Impact hammers operate by 

repeatedly dropping a heavy piston onto 

a pile to drive the pile into the substrate. 

Sound generated by impact hammers is 

characterized by rapid rise times and 

high peak levels, a potentially injurious 

combination (Hastings and Popper, 

2005). Vibratory hammers install piles 

by vibrating them and allowing the 

weight of the hammer to push them into 

the sediment. Vibratory hammers 

produce significantly less sound than 

impact hammers. Peak sound pressure 

levels (SPLs) may be 180 dB or greater, 

but are generally 10 to 20 dB lower than 

SPLs generated during impact pile 

driving of the same-sized pile (Oestman 

et al., 2009). Rise time is slower, 

reducing the probability and severity of 

injury, and sound energy is distributed 

over a greater amount of time (Nedwell 

and Edwards 2002; Carlson et al., 2005). 

A DTH hammer is essentially a drill 

bit that drills through the bedrock using 

a rotating function like a normal drill, 

in concert with a hammering 

mechanism operated by a pneumatic (or 

sometimes hydraulic) component 

integrated into the DTH hammer to 

increase speed of progress through the 

substrate (i.e., it is similar to a ‘‘hammer 

drill’’ hand tool). The sounds produced 

by the DTH method contain both a 

continuous non-impulsive component 

from the drilling action and an 

impulsive component from the 

hammering effect. Therefore, we treat 

DTH systems as both impulsive and 

non-impulsive sound source types 

simultaneously. 

The likely or possible impacts of 

CBS’s proposed activity on marine 

mammals involve both non-acoustic and 

acoustic stressors. Potential nonacoustic stressors could result from the 

physical presence of equipment and 

personnel; however, any impacts to 

marine mammals are expected to be 

primarily acoustic in nature. Acoustic 

stressors include effects of heavy 

equipment operation during pile driving 

and drilling. 

Acoustic Impacts 

The introduction of anthropogenic 

noise into the aquatic environment from 

pile driving or drilling is the primary 

means by which marine mammals may 

be harassed from the CBS’s specified 

activity. In general, animals exposed to 

natural or anthropogenic sound may 

experience physical and psychological 

effects, ranging in magnitude from none 

to severe (Southall et al., 2007). In 

general, exposure to pile driving or 

drilling noise has the potential to result 

in auditory threshold shifts and 

behavioral reactions (e.g., avoidance, 

temporary cessation of foraging and 

vocalizing, changes in dive behavior). 

Exposure to anthropogenic noise can 

also lead to non-observable 

physiological responses such an 

increase in stress hormones. Additional 

noise in a marine mammal’s habitat can 

mask acoustic cues used by marine 

mammals to carry out daily functions 

such as communication and predator 

and prey detection. The effects of pile 

driving or drilling noise on marine 

mammals are dependent on several 

factors, including, but not limited to, 

sound type (e.g., impulsive vs. nonimpulsive), the species, age and sex 

class (e.g., adult male vs. mom with 

calf), duration of exposure, the distance 

between the pile and the animal, 

received levels, behavior at time of 

exposure, and previous history with 

exposure (Wartzok et al., 2004; Southall 

et al., 2007). Here we discuss physical 

auditory effects (threshold shifts) 

followed by behavioral effects and 

potential impacts on habitat. 

NMFS defines a noise-induced 

threshold shift (TS) as a change, usually 

an increase, in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS 2018). The amount of 

threshold shift is customarily expressed 

in dB. TS can be permanent or 

temporary. As described in NMFS 

(2018), there are numerous factors to 

consider when examining the 

consequence of TS, including, but not 

limited to, the signal temporal pattern 

(e.g., impulsive or non-impulsive), 

likelihood an individual would be 

exposed for a long enough duration or 

to a high enough level to induce a TS, 

the magnitude of the TS, time to 

recovery (seconds to minutes or hours to 

days), the frequency range of the 

exposure (i.e., spectral content), the 

hearing and vocalization frequency 

range of the exposed species relative to 

the signal’s frequency spectrum (i.e., 

how an animal uses sound within the 

frequency band of the signal; e.g., 

Kastelein et al., 2014), and the overlap 

between the animal and the source (e.g., 

spatial, temporal, and spectral). 

Permanent Threshold Shift (PTS)— 

NMFS defines PTS as a permanent, 

irreversible increase in the threshold of 

audibility at a specified frequency or 

portion of an individual’s hearing range 

above a previously established reference 

level (NMFS 2018). Available data from 

humans and other terrestrial mammals 

indicate that a 40 dB threshold shift 

approximates PTS onset (see Ward et 

al., 1958, 1959; Ward 1960; Kryter et al., 

1966; Miller 1974; Ahroon et al., 1996; 

Henderson et al., 2008). PTS levels for 

marine mammals are estimates, as with 

the exception of a single study 

unintentionally inducing PTS in a 

harbor seal (Kastak et al., 2008), there 

are no empirical data measuring PTS in 

marine mammals largely due to the fact 

that, for various ethical reasons, 

experiments involving anthropogenic 

noise exposure at levels inducing PTS 

are not typically pursued or authorized 

(NMFS 2018). 

Temporary Threshold Shift (TTS)— 

TTS is a temporary, reversible increase 

in the threshold of audibility at a 

specified frequency or portion of an 

individual’s hearing range above a 

previously established reference level 

(NMFS 2018). Based on data from 

cetacean TTS measurements (see 

Southall et al., 2007), a TTS of 6 dB is 

considered the minimum threshold shift 

clearly larger than any day-to-day or 

session-to-session variation in a 

subject’s normal hearing ability 

(Schlundt et al., 2000; Finneran et al., 

2000, 2002). As described in Finneran 


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(2015), marine mammal studies have 

shown the amount of TTS increases 

with cumulative sound exposure level 

(SELcum) in an accelerating fashion: At 

low exposures with lower SELcum, the 

amount of TTS is typically small and 

the growth curves have shallow slopes. 

At exposures with higher SELcum, the 

growth curves become steeper and 

approach linear relationships with the 

noise SEL. 

Depending on the degree (elevation of 

threshold in dB), duration (i.e., recovery 

time), and frequency range of TTS, and 

the context in which it is experienced, 

TTS can have effects on marine 

mammals ranging from discountable to 

serious (similar to those discussed in 

auditory masking, below). For example, 

a marine mammal may be able to readily 

compensate for a brief, relatively small 

amount of TTS in a non-critical 

frequency range that takes place during 

a time when the animal is traveling 

through the open ocean, where ambient 

noise is lower and there are not as many 

competing sounds present. 

Alternatively, a larger amount and 

longer duration of TTS sustained during 

a time when communication is critical 

for successful mother/calf interactions 

could have more serious impacts. We 

note that reduced hearing sensitivity as 

a simple function of aging has been 

observed in marine mammals, as well as 

humans and other taxa (Southall et al., 

2007), so we can infer that strategies 

exist for coping with this condition to 

some degree, though likely not without 

cost. 

Many studies have examined noiseinduced hearing loss in marine 

mammals (see Finneran (2015) and 

Southall et al. (2019) for summaries). 

For cetaceans, published data on the 

onset of TTS are limited to the captive 

bottlenose dolphin (Tursiops truncatus), 

beluga whale (Delphinapterus leucas), 

harbor porpoise, and Yangtze finless 

porpoise (Neophocoena asiaeorientalis), 

and for pinnipeds in water, 

measurements of TTS are limited to 

harbor seals, elephant seals (Mirounga 

angustirostris), and California sea lions 

(Zalophus californianus). These studies 

examine hearing thresholds measured in 

marine mammals before and after 

exposure to intense sounds. The 

difference between the pre-exposure 

and post-exposure thresholds can be 

used to determine the amount of 

threshold shift at various post-exposure 

times. The amount and onset of TTS 

depends on the exposure frequency. 

Sounds at low frequencies, well below 

the region of best sensitivity, are less 

hazardous than those at higher 

frequencies, near the region of best 

sensitivity (Finneran and Schlundt, 

2013). At low frequencies, onset-TTS 

exposure levels are higher compared to 

those in the region of best sensitivity 

(i.e., a low frequency noise would need 

to be louder to cause TTS onset when 

TTS exposure level is higher), as shown 

for harbor porpoises and harbor seals 

(Kastelein et al., 2019a, 2019b). In 

addition, TTS can accumulate across 

multiple exposures, but the resulting 

TTS will be less than the TTS from a 

single, continuous exposure with the 

same SEL (Finneran et al., 2010; 

Kastelein et al., 2014; Kastelein et al., 

2015a; Mooney et al., 2009). This means 

that TTS predictions based on the total, 

cumulative SEL will overestimate the 

amount of TTS from intermittent 

exposures such as sonars and impulsive 

sources. Nachtigall et al. (2018) describe 

the measurements of hearing sensitivity 

of multiple odontocete species 

(bottlenose dolphin, harbor porpoise, 

beluga, and false killer whale 

(Pseudorca crassidens)) when a 

relatively loud sound was preceded by 

a warning sound. These captive animals 

were shown to reduce hearing 

sensitivity when warned of an 

impending intense sound. Based on 

these experimental observations of 

captive animals, the authors suggest that 

wild animals may dampen their hearing 

during prolonged exposures or if 

conditioned to anticipate intense 

sounds. Another study showed that 

echolocating animals (including 

odontocetes) might have anatomical 

specializations that might allow for 

conditioned hearing reduction and 

filtering of low-frequency ambient 

noise, including increased stiffness and 

control of middle ear structures and 

placement of inner ear structures 

(Ketten et al., 2021). Data available on 

noise-induced hearing loss for 

mysticetes are currently lacking (NMFS, 

2018). 

Behavioral Harassment—Exposure to 

noise from pile driving and removal also 

has the potential to behaviorally disturb 

marine mammals. Available studies 

show wide variation in response to 

underwater sound; therefore, it is 

difficult to predict specifically how any 

given sound in a particular instance 

might affect marine mammals 

perceiving the signal. If a marine 

mammal does react briefly to an 

underwater sound by changing its 

behavior or moving a small distance, the 

impacts of the change are unlikely to be 

significant to the individual, let alone 

the stock or population. However, if a 

sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on individuals and populations 

could be significant (e.g., Lusseau and 

Bejder 2007; Weilgart 2007). 

Disturbance may result in changing 

durations of surfacing and dives, 

number of blows per surfacing, or 

moving direction and/or speed; 

reduced/increased vocal activities; 

changing/cessation of certain behavioral 

activities (such as socializing or 

feeding); visible startle response or 

aggressive behavior (such as tail/fluke 

slapping or jaw clapping); avoidance of 

areas where sound sources are located. 

Pinnipeds may increase their haul out 

time, possibly to avoid in-water 

disturbance (Thorson and Reyff 2006). 

Behavioral responses to sound are 

highly variable and context-specific and 

any reactions depend on numerous 

intrinsic and extrinsic factors (e.g., 

species, state of maturity, experience, 

current activity, reproductive state, 

auditory sensitivity, time of day), as 

well as the interplay between factors 

(e.g., Richardson et al., 1995; Wartzok et 

al., 2003; Southall et al., 2007; Weilgart 

2007). Behavioral reactions can vary not 

only among individuals but also within 

an individual, depending on previous 

experience with a sound source, 

context, and numerous other factors 

(Ellison et al., 2012), and can vary 

depending on characteristics associated 

with the sound source (e.g., whether it 

is moving or stationary, number of 

sources, distance from the source). In 

general, pinnipeds seem more tolerant 

of, or at least habituate more quickly to, 

potentially disturbing underwater sound 

than do cetaceans, and generally seem 

to be less responsive to exposure to 

industrial sound than most cetaceans. 

Please see Appendices B–C of Southall 

et al. (2007) for a review of studies 

involving marine mammal behavioral 

responses to sound. 

Disruption of feeding behavior can be 

difficult to correlate with anthropogenic 

sound exposure, so it is usually inferred 

by observed displacement from known 

foraging areas, the appearance of 

secondary indicators (e.g., bubble nets 

or sediment plumes), or changes in dive 

behavior. As for other types of 

behavioral response, the frequency, 

duration, and temporal pattern of signal 

presentation, as well as differences in 

species sensitivity, are likely 

contributing factors to differences in 

response in any given circumstance 

(e.g., Croll et al., 2001; Nowacek et al., 

2004; Madsen et al., 2006; Yazvenko et 

al., 2007). A determination of whether 

foraging disruptions incur fitness 

consequences would require 

information on or estimates of the 

energetic requirements of the affected 

individuals and the relationship 

between prey availability, foraging effort 


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and success, and the life history stage of 

the animal. 

Stress responses—An animal’s 

perception of a threat may be sufficient 

to trigger stress responses consisting of 

some combination of behavioral 

responses, autonomic nervous system 

responses, neuroendocrine responses, or 

immune responses (e.g., Seyle 1950; 

Moberg 2000). In many cases, an 

animal’s first and sometimes most 

economical (in terms of energetic costs) 

response is behavioral avoidance of the 

potential stressor. Autonomic nervous 

system responses to stress typically 

involve changes in heart rate, blood 

pressure, and gastrointestinal activity. 

These responses have a relatively short 

duration and may or may not have a 

significant long-term effect on an 

animal’s fitness. 

Neuroendocrine stress responses often 

involve the hypothalamus-pituitaryadrenal system. Virtually all 

neuroendocrine functions that are 

affected by stress—including immune 

competence, reproduction, metabolism, 

and behavior—are regulated by pituitary 

hormones. Stress-induced changes in 

the secretion of pituitary hormones have 

been implicated in failed reproduction, 

altered metabolism, reduced immune 

competence, and behavioral disturbance 

(e.g., Moberg 1987; Blecha 2000). 

Increases in the circulation of 

glucocorticoids are also equated with 

stress (Romano et al., 2004). 

The primary distinction between 

stress (which is adaptive and does not 

normally place an animal at risk) and 

‘‘distress’’ is the cost of the response. 

During a stress response, an animal uses 

glycogen stores that can be quickly 

replenished once the stress is alleviated. 

In such circumstances, the cost of the 

stress response would not pose serious 

fitness consequences. However, when 

an animal does not have sufficient 

energy reserves to satisfy the energetic 

costs of a stress response, energy 

resources must be diverted from other 

functions. This state of distress will last 

until the animal replenishes its 

energetic reserves sufficient to restore 

normal function. 

Relationships between these 

physiological mechanisms, animal 

behavior, and the costs of stress 

responses are well studied through 

controlled experiments and for both 

laboratory and free-ranging animals 

(e.g., Holberton et al., 1996; Hood et al., 

1998; Jessop et al., 2003; Lankford et al., 

2005). Stress responses due to exposure 

to anthropogenic sounds or other 

stressors and their effects on marine 

mammals have also been reviewed (Fair 

and Becker 2000; Romano et al., 2002b) 

and, more rarely, studied in wild 

populations (e.g., Romano et al., 2002a). 

For example, Rolland et al. (2012) found 

that noise reduction from reduced ship 

traffic in the Bay of Fundy was 

associated with decreased stress in 

North Atlantic right whales. These and 

other studies lead to a reasonable 

expectation that some marine mammals 

will experience physiological stress 

responses upon exposure to acoustic 

stressors and that it is possible that 

some of these would be classified as 

‘‘distress.’’ In addition, any animal 

experiencing TTS would likely also 

experience stress responses (National 

Research Council (NRC), 2003), however 

distress is an unlikely result of this 

project based on observations of marine 

mammals during previous, similar 

projects in the area. 

Masking—Sound can disrupt behavior 

through masking, or interfering with, an 

animal’s ability to detect, recognize, or 

discriminate between acoustic signals of 

interest (e.g., those used for intraspecific 

communication and social interactions, 

prey detection, predator avoidance, 

navigation) (Richardson et al., 1995). 

Masking occurs when the receipt of a 

sound is interfered with by another 

coincident sound at similar frequencies 

and at similar or higher intensity, and 

may occur whether the sound is natural 

(e.g., snapping shrimp, wind, waves, 

precipitation) or anthropogenic (e.g., 

pile driving, shipping, sonar, seismic 

exploration) in origin. The ability of a 

noise source to mask biologically 

important sounds depends on the 

characteristics of both the noise source 

and the signal of interest (e.g., signal-tonoise ratio, temporal variability, 

direction), in relation to each other and 

to an animal’s hearing abilities (e.g., 

sensitivity, frequency range, critical 

ratios, frequency discrimination, 

directional discrimination, age or TTS 

hearing loss), and existing ambient 

noise and propagation conditions. 

Masking of natural sounds can result 

when human activities produce high 

levels of background sound at 

frequencies important to marine 

mammals. Conversely, if the 

background level of underwater sound 

is high (e.g., on a day with strong wind 

and high waves), an anthropogenic 

sound source would not be detectable as 

far away as would be possible under 

quieter conditions and would itself be 

masked. 

Airborne Acoustic Effects—Although 

pinnipeds are known to haul out 

regularly on man-made objects, we 

believe that incidents of take resulting 

solely from airborne sound are unlikely 

due to the sheltered proximity between 

the proposed project area and haulout 

sites (outside of Sitka Channel). There is 

a possibility that an animal could 

surface in-water, but with head out, 

within the area in which airborne sound 

exceeds relevant thresholds and thereby 

be exposed to levels of airborne sound 

that we associate with harassment, but 

any such occurrence would likely be 

accounted for in our estimation of 

incidental take from underwater sound. 

Therefore, authorization of incidental 

take resulting from airborne sound for 

pinnipeds is not warranted, and 

airborne sound is not discussed further 

here. Cetaceans are not expected to be 

exposed to airborne sounds that would 

result in harassment as defined under 

the MMPA. 

Marine Mammal Habitat Effects 

CBS’s construction activities could 

have localized, temporary impacts on 

marine mammal habitat and their prey 

by increasing in-water sound pressure 

levels and slightly decreasing water 

quality. However, its proposed location 

is within the Sitka harbor and is located 

in an area that is currently used by 

numerous commercial fishing and 

personal vessels. Construction activities 

are of short duration and would likely 

have temporary impacts on marine 

mammal habitat through increases in 

underwater and airborne sound. 

Increased noise levels may affect 

acoustic habitat (see masking discussion 

above) and adversely affect marine 

mammal prey in the vicinity of the 

project area (see discussion below). 

During DTH drilling, impact, and 

vibratory pile driving, elevated levels of 

underwater noise would ensonify the 

project area where both fish and 

mammals occur and could affect 

foraging success. Additionally, marine 

mammals may avoid the area during 

construction; however, displacement 

due to noise is expected to be temporary 

and is not expected to result in longterm effects to the individuals or 

populations. 

Temporary and localized increase in 

turbidity near the seafloor would occur 

in the immediate area surrounding the 

area where piles are installed or 

removed. In general, turbidity 

associated with pile installation is 

localized to about a 25-ft (7.6 m) radius 

around the pile (Everitt et al., 1980). The 

sediments of the project site would 

settle out rapidly when disturbed. 

Cetaceans are not expected to be close 

enough to the pile driving areas to 

experience effects of turbidity, and any 

pinnipeds could avoid localized areas of 

turbidity. Therefore, we expect the 

impact from increased turbidity levels 

to be discountable to marine mammals 

and do not discuss it further. 


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In-Water Construction Effects on 

Potential Foraging Habitat 

The proposed activities would not 

result in permanent impacts to habitats 

used directly by marine mammals as the 

project would not expand outside of the 

Sitka Channel, and no increases in 

vessel traffic in the area are expected as 

a result of this project. The total seafloor 

area likely impacted by the project is 

relatively small compared to the 

available habitat in Southeast Alaska. 

Sitka Sound is included as a BIA for 

humpback whales and gray whales, 

however the action area is within the 

breakwaters where baleen whales are 

rare. Additionally, the area already has 

elevated noise levels because of busy 

vessel traffic transiting through the area, 

and critical habitat impacts would not 

be permanent nor would it result longterm effects to the local population. No 

known rookeries or major haulouts 

would be impacted. Additionally, the 

total seafloor area affected by pile 

installation and removal is a small area 

compared to the vast foraging area 

available to marine mammals in the 

area. At best, the impact area provides 

marginal foraging habitat for marine 

mammals and fishes. Furthermore, pile 

driving at the project site would not 

obstruct movements or migration of 

marine mammals. 

Effects on Potential Prey 

Sound may affect marine mammals 

through impacts on the abundance, 

behavior, or distribution of prey species 

(e.g., crustaceans, cephalopods, fish, 

zooplankton, etc.). Marine mammal prey 

varies by species, season, and location. 

Here, we describe studies regarding the 

effects of noise on known marine 

mammal prey. 

Fish utilize the soundscape and 

components of sound in their 

environment to perform important 

functions such as foraging, predator 

avoidance, mating, and spawning (e.g., 

Zelick and Mann, 1999; Fay, 2009). 

Depending on their hearing anatomy 

and peripheral sensory structures, 

which vary among species, fishes hear 

sounds using pressure and particle 

motion sensitivity capabilities and 

detect the motion of surrounding water 

(Fay et al., 2008). The potential effects 

of noise on fishes depends on the 

overlapping frequency range, distance 

from the sound source, water depth of 

exposure, and species-specific hearing 

sensitivity, anatomy, and physiology. 

Key impacts to fishes may include 

behavioral responses, hearing damage, 

barotrauma (pressure-related injuries), 

and mortality. 

Fish react to sounds which are 

especially strong and/or intermittent 

low-frequency sounds, and behavioral 

responses such as flight or avoidance 

are the most likely effects. Short 

duration, sharp sounds can cause overt 

or subtle changes in fish behavior and 

local distribution. The reaction of fish to 

noise depends on the physiological state 

of the fish, past exposures, motivation 

(e.g., feeding, spawning, migration), and 

other environmental factors. Hastings 

and Popper (2005) identified several 

studies that suggest fish may relocate to 

avoid certain areas of sound energy. 

Additional studies have documented 

effects of pile driving on fish, although 

several are based on studies in support 

of large, multiyear bridge construction 

projects (e.g., Scholik and Yan, 2001, 

2002; Popper and Hastings, 2009). 

Several studies have demonstrated that 

impulse sounds might affect the 

distribution and behavior of some 

fishes, potentially impacting foraging 

opportunities or increasing energetic 

costs (e.g., Fewtrell and McCauley, 

2012; Pearson et al., 1992; Skalski et al., 

1992; Santulli et al., 1999; Paxton et al., 

2017). However, some studies have 

shown no or slight reaction to impulse 

sounds (e.g., Wardle et al., 2001; 

Jorgenson and Gyselman, 2009). 

SPLs of sufficient strength have been 

known to cause injury to fish and fish 

mortality. However, in most fish 

species, hair cells in the ear 

continuously regenerate and loss of 

auditory function likely is restored 

when damaged cells are replaced with 

new cells. Halvorsen et al. (2012a) 

showed that a TTS of 4–6 dB was 

recoverable within 24 hours for one 

species. Impacts would be most severe 

when the individual fish is close to the 

source and when the duration of 

exposure is long. Injury caused by 

barotrauma can range from slight to 

severe and can cause death, and is most 

likely for fish with swim bladders. 

Barotrauma injuries have been 

documented during controlled exposure 

to impact pile driving (Halvorsen et al., 

2012b; Casper et al., 2013). 

The most likely impact to fish from 

pile driving activities at the project 

areas would be temporary behavioral 

avoidance of the area. The duration of 

fish avoidance of an area after pile 

driving stops is unknown, but a rapid 

return to normal recruitment, 

distribution and behavior is anticipated. 

Construction activities, in the form of 

increased turbidity, have the potential 

to adversely affect forage fish in the 

project area. Forage fish form a 

significant prey base for many marine 

mammal species that occur in the 

project area. Increased turbidity is 

expected to occur in the immediate 

vicinity (on the order of 10 ft (3 m) or 

less) of construction activities. However, 

suspended sediments and particulates 

are expected to dissipate quickly within 

a single tidal cycle. Given the limited 

area affected and high tidal dilution 

rates, any effects on forage fish are 

expected to be minor or negligible. 

Avoidance by potential prey (i.e., fish) 

of the immediate area due to the 

temporary loss of this foraging habitat is 

also possible. The duration of fish 

avoidance of this area after pile driving 

stops is unknown, but a rapid return to 

normal recruitment, distribution and 

behavior is anticipated. Any behavioral 

avoidance by fish of the disturbed area 

would still leave significantly large 

areas of fish and marine mammal 

foraging habitat in the nearby vicinity. 

In summary, given the short daily 

duration of sound associated with 

individual pile driving events and the 

relatively small areas being affected, 

pile driving activities associated with 

the proposed action are not likely to 

have a permanent adverse effect on any 

fish habitat, or populations of fish 

species. Any behavioral avoidance by 

fish of the disturbed area would still 

leave significantly large areas of fish and 

marine mammal foraging habitat in the 

nearby vicinity. Thus, we conclude that 

impacts of the specified activity are not 

likely to have more than short-term 

adverse effects on any prey habitat or 

populations of prey species. Further, 

any impacts to marine mammal habitat 

are not expected to result in significant 

or long-term consequences for 

individual marine mammals, or to 

contribute to adverse impacts on their 

populations. 

Estimated Take of Marine Mammals 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through the IHA, 

which will inform both NMFS’ 

consideration of ‘‘small numbers,’’ and 

the negligible impact determinations. 

Harassment is the only type of take 

expected to result from these activities. 

Except with respect to certain activities 

not pertinent here, section 3(18) of the 

MMPA defines ‘‘harassment’’ as any act 

of pursuit, torment, or annoyance, 

which (i) has the potential to injure a 

marine mammal or marine mammal 

stock in the wild (Level A harassment); 

or (ii) has the potential to disturb a 

marine mammal or marine mammal 

stock in the wild by causing disruption 

of behavioral patterns, including, but 

not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

(Level B harassment). 


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Authorized takes would primarily be 

by Level B harassment, as use of the 

acoustic sources (i.e., vibratory or 

impact pile driving and DTH drilling) 

has the potential to result in disruption 

of behavioral patterns for individual 

marine mammals. There is also some 

potential for auditory injury (Level A 

harassment) to result, primarily for 

harbor porpoise, harbor seals and Steller 

sea lions. Harbor porpoise have larger 

predicted auditory injury zones and due 

to their small size they could enter the 

Level A harassment zone and remain 

undetected for sufficient duration to 

incur auditory injury. While Steller sea 

lion do not have large Level A 

harassment zones, they are frequently 

sighted in the project area and therefor 

have some potential for auditory injury. 

Additionally harbor seals have larger 

Level A harassment zones and are 

common in the action area, and 

therefore have potential for auditory 

injury. Auditory injury is unlikely to 

occur for all other species, based on the 

unlikelihood of the species in the action 

area and the smaller Level A harassment 

zones. The proposed mitigation and 

monitoring measures are expected to 

minimize the severity of the taking to 

the extent practicable. 

As described previously, no serious 

injury or mortality is anticipated or 

proposed to be authorized for this 

activity. Below we describe how the 

proposed take numbers are estimated. 

For acoustic impacts, generally 

speaking, we estimate take by 

considering: (1) acoustic thresholds 

above which NMFS believes the best 

available science indicates marine 

mammals will be behaviorally harassed 

or incur some degree of permanent 

hearing impairment; (2) the area or 

volume of water that will be ensonified 

above these levels in a day; (3) the 

density or occurrence of marine 

mammals within these ensonified areas; 

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

We note that while these factors can 

contribute to a basic calculation to 

provide an initial prediction of potential 

takes, additional information that can 

qualitatively inform take estimates is 

also sometimes available (e.g., previous 

monitoring results or average group 

size). Below, we describe the factors 

considered here in more detail and 

present the proposed take estimates. 

Acoustic Thresholds 

NMFS recommends the use of 

acoustic thresholds that identify the 

received level of underwater sound 

above which exposed marine mammals 

would be reasonably expected to be 

behaviorally harassed (equated to Level 

B harassment) or to incur PTS of some 

degree (equated to Level A harassment). 

Level B Harassment—Though 

significantly driven by received level, 

the onset of behavioral disturbance from 

anthropogenic noise exposure is also 

informed to varying degrees by other 

factors related to the source or exposure 

context (e.g., frequency, predictability, 

duty cycle, duration of the exposure, 

signal-to-noise ratio, distance to the 

source), the environment (e.g., 

bathymetry, other noises in the area, 

predators in the area), and the receiving 

animals (hearing, motivation, 

experience, demography, life stage, 

depth) and can be difficult to predict 

(e.g., Southall et al., 2007, 2021, Ellison 

et al., 2012). Based on what the 

available science indicates and the 

practical need to use a threshold based 

on a metric that is both predictable and 

measurable for most activities, NMFS 

typically uses a generalized acoustic 

threshold based on received level to 

estimate the onset of behavioral 

harassment. NMFS generally predicts 

that marine mammals are likely to be 

behaviorally harassed in a manner 

considered to be Level B harassment 

when exposed to underwater 

anthropogenic noise above root-meansquared pressure received levels (RMS 

SPL) of 120 dB (referenced to 1 

micropascal (re 1 mPa)) for continuous 

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

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

airguns) or intermittent (e.g., scientific 

sonar) sources. Generally speaking, 

Level B harassment take estimates based 

on these behavioral harassment 

thresholds are expected to include any 

likely takes by TTS as, in most cases, 

the likelihood of TTS occurs at 

distances from the source less than 

those at which behavioral harassment is 

likely. TTS of a sufficient degree can 

manifest as behavioral harassment, as 

reduced hearing sensitivity and the 

potential reduced opportunities to 

detect important signals (conspecific 

communication, predators, prey) may 

result in changes in behavior patterns 

that would not otherwise occur. 

CBS’s proposed activity includes the 

use of continuous (vibratory hammer 

and DTH drilling) and impulsive (DTH 

drilling and impact pile driving) 

sources, and therefore the RMS SPL 

thresholds of 120 and 160 dB re 1 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). CBS’s proposed activity 

includes the use of impulsive (impact 

pile-driving and DTH drilling) and nonimpulsive (vibratory hammer and DTH 

drilling) sources. 

These thresholds are provided in the 

table below. The references, analysis, 

and methodology used in the 

development of the thresholds are 

described in NMFS’ 2018 Technical 

Guidance, which may be accessed at: 

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

national/marine-mammal-protection/ 

marine-mammal-acoustic-technicalguidance. 

TABLE 5—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

Hearing group 

PTS onset acoustic thresholds * 

(received level) 

Impulsive Non-impulsive 

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

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

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

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

Otariid Pinnipeds (OW) (Underwater) ............................. Cell 9: Lpk,flat: 232 dB; LE,OW,24h: 203 dB ....................... Cell 10: LE,OW,24h: 219 dB. 

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should 

also be considered. 


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Note: Peak sound pressure (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1 μPa2s. 

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

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

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

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

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

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

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

Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that are used in estimating the area 

ensonified above the acoustic 

thresholds, including source levels and 

transmission loss coefficient. 

The sound field in the project area is 

the existing background noise plus 

additional construction noise from the 

proposed project. Marine mammals are 

expected to be affected via sound 

generated by the primary components of 

the project (i.e., impact pile driving, 

vibratory pile driving and removal, and 

DTH). 

In order to calculate distances to the 

Level A harassment and Level B 

harassment thresholds for the methods 

and piles being used in this project, 

NMFS used acoustic monitoring data 

from other locations to develop source 

levels for the various pile types, sizes 

and methods (table 6). This analysis 

uses practical spreading loss, a standard 

assumption regarding sound 

propagation for similar environments, to 

estimate transmission of sound through 

water. For this analysis, the 

transmission loss factor of 15 (4.5 dB 

per doubling of distance) is used. A 

weighting adjustment factor of 2.5 or 2, 

a standard default value for vibratory 

pile driving and removal or impact 

driving and DTH respectively, were 

used to calculate Level A harassment 

areas. 

NMFS recommends treating DTH 

systems as both impulsive and 

continuous, non-impulsive sound 

source types simultaneously. Thus, 

impulsive thresholds are used to 

evaluate Level A harassment, and 

continuous thresholds are used to 

evaluate Level B harassment. With 

regards to DTH mono-hammers, NMFS 

recommends proxy levels for Level A 

harassment based on available data 

regarding DTH systems of similar sized 

piles and holes (Denes et al., 2019; Guan 

and Miner, 2020; Reyff and Heyvaert, 

2019; Reyff, 2020; Heyvaert and Reyff, 

2021) (table 1 and 2 includes number of 

piles and duration for each phase; table 

6 includes peak pressure, sound 

pressure, and sound exposure levels for 

each pile type). 

TABLE 6—ESTIMATES UNDERWATER PROXY SOURCE LEVEL FOR PILE INSTALLATION AND REMOVAL

Method and pile type Sound source at 10 meters Source 

Vibratory Hammer dB rms 

16 in ................................................................................ 161 NAVFAC 2015. 

24 in ................................................................................ 161 NAVFAC 2015. 

DTH Drill dB rms dB SEL dB peak 

16 in ............................................................................... 167 146 172 Heyvaert and Reyff 2021, Guan and Miner 2020. 

24 in ............................................................................... 167 159 184 Heyvaert and Reyff 2021. 

Impact Hammer dB rms dB SEL dB peak 

16 in ............................................................................... 185 175 200 Caltrans 2020. 

24 in ............................................................................... 190 177 203 Caltrans 2015. 

Level B Harassment Zones 

Transmission loss (TL) is the decrease 

in acoustic intensity as an acoustic 

pressure wave propagates out from a 

source. TL parameters vary with 

frequency, temperature, sea conditions, 

current, source and receiver depth, 

water depth, water chemistry, and 

bottom composition and topography. 

The general formula for underwater TL 

is: 

TL = B * log10 (R1/R2), 

Where: 

TL = transmission loss in dB 

B = transmission loss coefficient; for practical 

spreading equals 15 

R1 = the distance of the modeled SPL from 

the driven pile, and 

R2 = the distance from the driven pile of the 

initial measurement. 

The recommended TL coefficient for 

most nearshore environments is the 

practical spreading value of 15. This 

value results in an expected propagation 

environment that would lie between 

spherical and cylindrical spreading loss 

conditions, which is the most 

appropriate assumption for CBS’s 

proposed underwater activities. The 

Level B harassment zones and 

approximate amount of area ensonified 

for the proposed underwater activities 

are shown in table 7. 

Level A Harassment Zones 

The ensonified area associated with 

Level A harassment is more technically 

challenging to predict due to the need 

to account for a duration component. 

Therefore, NMFS developed an optional 

User Spreadsheet tool to accompany the 

Technical Guidance that can be used to 

relatively simply predict an isopleth 

distance for use in conjunction with 

marine mammal density or occurrence 

to help predict potential takes. We note 

that because of some of the assumptions 

included in the methods underlying this 

optional tool, we anticipate that the 

resulting isopleth estimates are typically 

going to be overestimates of some 

degree, which may result in an 

overestimate of potential take by Level 

A harassment. However, this optional 

tool offers the best way to estimate 

isopleth distances when more 

sophisticated modeling methods are not 

available or practical. For stationary 

sources such as pile installation or 

removal, the optional User Spreadsheet 


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tool predicts the distance at which, if a 

marine mammal remained at that 

distance for the duration of the activity, 

it would be expected to incur PTS. The 

isopleths generated by the User 

Spreadsheet used the same TL 

coefficient as the Level B harassment 

zone calculations (i.e., the practical 

spreading value of 15). Inputs used in 

the User Spreadsheet (e.g., number of 

piles per day, duration and/or strikes 

per pile) are presented in tables 1 and 

2. The maximum RMS SPL, SEL, and 

resulting isopleths are reported in tables 

6 and 7. 

TABLE 7—LEVEL A AND LEVEL B HARASSMENT ISOPLETHS FOR PILE DRIVING ACTIVITIES

Activity 

Level A isopleth 

(m) Level B 

isopleth 

(m) LF MF HF Phocids Otariids 

Vibratory Pile Removal/Installation 

Phase I: 

16-in temp install ........................................................................................ 6.8 0.6 10.1 4.2 0.3 5,411.7 

16-in temp removal .................................................................................... 6.8 0.6 10.1 4.2 0.3 5,411.7 

16-in perm install ....................................................................................... 6.8 0.6 10.1 4.2 0.3 5,411.7 

24-in perm install ....................................................................................... 6.8 0.6 10.1 4.2 0.3 5,411.7 

Phase II: 

16-in temp install ........................................................................................ 6.8 0.6 10.1 4.2 0.3 5,411.7 

16-in temp removal .................................................................................... 6.8 0.6 10.1 4.2 0.3 5,411.7 

24-in perm install ....................................................................................... 6.8 0.6 10.1 4.2 0.3 5,411.7 

DTH Pile Installation 

Phase I: 

16-in perm install ....................................................................................... 59 2.1 70.3 31.6 2.3 1 8,500 

24-in perm install ....................................................................................... 568.9 20.2 677.6 304.4 22.2 1 8,500 

Phase II: 

24-in perm install ....................................................................................... 568.9 20.2 677.6 304.4 22.2 1 8,500 

Impact Pile Installation 

Phase I: 

16-in temp install ........................................................................................ 231 8.2 275 123 9 464.2 

16-in perm install ....................................................................................... 231 8.2 275 123 9 464.2 

24-in perm install ....................................................................................... 313 11.1 373 168 12.2 1,000 

Phase II: 

16-in temp install ........................................................................................ 231 8.2 275 123 9 464.2 

24-in perm install ....................................................................................... 313 11.1 373 168 12.2 1,000 

1The calculated Level B harassment zone is 13,594 m. However, the farthest distance that sound will transmit from the source is 8,500 m before transmission is 

stopped by landmasses. 

Marine Mammal Occurrence 

In this section we provide information 

about the occurrence of marine 

mammals, including density or other 

relevant information which will inform 

the take calculations. 

Daily occurrence probability of each 

marine mammal species in the action 

area is based on consultation with 

previous monitoring reports, local 

researchers and marine professionals. 

Occurrence probability estimates are 

based on conservative density 

approximations for each species and 

factor in historic data of occurrence, 

seasonality, and group size in Sitka 

Sound and Sitka Channel. A summary 

of proposed occurrence is shown in 

table 9. To accurately describe species 

occurrence near the action area, marine 

mammals were described as either 

common (species sighted consistently 

during all monitoring efforts in the 

project vicinity, assume one to two 

groups per day), frequent (species 

sighted with some consistency during 

most monitoring efforts in the project 

vicinity, assume one group per week), or 

infrequent (species sighted occasionally 

during a few monitoring efforts in the 

project vicinity, assume one group per 

2 weeks). 

TABLE 8—ESTIMATED OCCURRENCE OF GROUP SIGHTINGS OF MARINE MAMMAL SPECIES

Species Frequency Average group 

size Expected occurrence 

Humpback whale .................................................... Frequent ................................................................. 3.4 1 group/week. 

Minke whale 1 .......................................................... Infrequent ............................................................... 3.5 1 group/2 weeks. 

Gray whale .............................................................. Infrequent ............................................................... 3.5 1 group/2 weeks. 

Killer whale .............................................................. Frequent ................................................................. 6.6 1 group/week. 

Harbor porpoise ...................................................... Infrequent ............................................................... 5.0 1 group/2 weeks. 

Harbor seal 2 ........................................................... Common ................................................................. 2.1 1–2 groups/day. 

Steller sea lion 2 ...................................................... Common ................................................................. 2.0 1–2 groups/day. 

1 Minke whale considered rare in Sitka Channel, but to be conservative they are treated as infrequent for take estimation as there is a small 

likelihood they could be in the area during the activity. 2 Likelihood of one group/day in the Level A harassment zone and likelihood of two groups/day in the level B harassment zone. 


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Take Estimation 

Here we describe how the information 

provided above is synthesized to 

produce a quantitative estimate of the 

take that is reasonably likely to occur 

and proposed for authorization. 

For the total underwater take 

estimate, the daily occurrence 

probability for a species was multiplied 

by the estimated group size and by the 

number of days of each type of pile 

driving activity. Group size is based on 

the best available published research for 

these species and their presence in the 

action area. 

Estimated take = Group size × Groups 

per day × Days of pile driving activity 

Take by Level A harassment is 

requested for Steller sea lions and 

harbor seals. Although Steller sea lion 

Level A harassment zones are small, as 

previously discussed they are known to 

spend extended periods of time within 

the breakwaters in Sitka sound and in 

the project area. Harbor seals are also 

common in the project area and 

although their Level A harassment 

zones are farther from the project area, 

CBS has requested a maximum 

shutdown zone of 125 m for harbor seals 

and therefor there is likelihood for take 

by Level A harassment of harbor seals. 

Take by Level A harassment is also 

requested for harbor porpoise. We are 

proposing a maximum shutdown zone 

for high frequency species of 300 m and 

therefor there is likelihood for some take 

by Level A harassment. Even though 

they are not as common within the 

breakwaters, their Level A harassment 

zone extends beyond the breakwaters 

and they are elusive in nature. The take 

by Level A harassment for both 

pinniped species, are based on a lower 

daily occurrence rate based on the 

frequency of sightings within the 

smaller Level A harassment zone of the 

breakwaters (table 8). 

Additionally, for species that are large 

and/or infrequent (gray whale, minke 

whale, humpback whale, and harbor 

porpoise) in Sitka Sound and are 

unlikely to be within the breakwaters 

where the proposed action will take 

place, take by Level B harassment is 

only anticipated to occur incidental to 

vibratory and DTH methods, given the 

larger Level B harassment zones which 

will extend beyond the breakwaters. 

Anticipated take by Level A harassment 

for harbor seal and harbor porpoise 

would likely occur only incidental to 

impact pile driving and DTH drilling, 

and anticipated take of Steller sea lion 

by Level A harassment would likely 

occur only incidental to DTH drilling, 

due to the larger Level A harassment 

zones for these activities. See table 7. 

TABLE 9—PROPOSED TAKE OF MARINE MAMMALS BY LEVEL A AND LEVEL B HARASSMENT AND PERCENT OF STOCK

PROPOSED TO BE TAKEN

Species Stock 

Phase 1 Phase 2 

Level A Level B Percent of 

stock Level A Level B Percent of stock 

Humpback whale 1 ............................. Hawai1i ............................................... 0 11 0.1 0 * 4 0 

Mexico-North Pacific 2 ....................... 0 0 0 0 0 0 

Gray Whale ........................................ Eastern North Pacific ........................ 0 6 0 0 * 4 0 

Minke Whale ...................................... Alaska ............................................... 0 6 NA 0 * 4 NA 

Killer whale ........................................ West Coast Transients ..................... 0 3 0.9 0 1 0.3 

Gulf, Aleutian, Bering Transient ........ 0 6 0.9 0 2 0.3 

Northern Resident ............................. 0 3 0.9 0 1 0.3 

Alaska Resident ................................ 0 18 0.9 0 6 0.3 

Harbor porpoise ................................. Northern Southeast Alaska ............... * 5 8 0.9 * 5 * 5 0.7 

Harbor seal ........................................ Sitka/Chatham Alaska ....................... 48 130 1.3 13 38 0.4 

Steller sea lion ................................... Eastern US ........................................ 16 121 0.3 6 35 0.1 

Western US ....................................... 0 3 0 0 2* 0 

1Take estimates are weighted based on calculated percentages of population for each distinct stock, assuming animals present would follow same probability of 

presence in project area. Humpback whale probability by stock based on Southeast Alaska estimates from NMFS 2021 (98 percent Hawaii DPS; 2 percent Mexico 

DPS). 2ESA listed Mexico humpback whales take calculation resulted in less than 0.5 takes, therefore no takes are anticipate or are proposed for authorization. 

* Where proposed calculated take was less than the average group size, the take was rounded up to a group size as that is likely what would be encountered. 

Proposed Mitigation 

In order to issue an IHA under section 

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

set forth the permissible methods of 

taking pursuant to the activity, and 

other means of effecting the least 

practicable impact on the species or 

stock and its habitat, paying particular 

attention to rookeries, mating grounds, 

and areas of similar significance, and on 

the availability of the species or stock 

for taking for certain subsistence uses. 

NMFS regulations require applicants for 

incidental take authorizations to include 

information about the availability and 

feasibility (economic and technological) 

of equipment, methods, and manner of 

conducting the activity or other means 

of effecting the least practicable adverse 

impact upon the affected species or 

stocks, and their habitat (50 CFR 

216.104(a)(11)). 

In evaluating how mitigation may or 

may not be appropriate to ensure the 

least practicable adverse impact on 

species or stocks and their habitat, as 

well as subsistence uses where 

applicable, NMFS considers two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat, as well as 

subsistence uses. This considers the 

nature of the potential adverse impact 

being mitigated (likelihood, scope, 

range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

implemented as planned), the 

likelihood of effective implementation 

(probability implemented as planned), 

and; 

(2) The practicability of the measures 

for applicant implementation, which 

may consider such things as cost, and 

impact on operations. 

Mitigation Measures 

For each IHA, CBS must follow 

mitigation measures as specified below: 

• Ensure that construction 

supervisors and crews, the monitoring 

team, and relevant CBS staff are trained 

prior to the start of all pile driving and 

DTH drilling activity, so that 

responsibilities, communication 

procedures, monitoring protocols, and 

operational procedures are clearly 

understood. New personnel joining 

during the project must be trained prior 

to commencing work; 

• Employ Protected Species 

Observers (PSOs) and establish 


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monitoring locations as described in the 

application and the IHA. The Holder 

must monitor the project area to the 

maximum extent possible based on the 

required number of PSOs, required 

monitoring locations, and 

environmental conditions. For all pile 

driving and removal at least one PSO 

must be used. The PSO will be stationed 

as close to the activity as possible; 

• The placement of the PSOs during 

all pile driving and removal and DTH 

drilling activities will ensure that the 

entire shutdown zone is visible during 

pile installation; 

• Monitoring must take place from 30 

minutes prior to initiation of pile 

driving or DTH drilling activity (i.e., 

pre-clearance monitoring) through 30 

minutes post-completion of pile driving 

or DTH drilling activity; 

• Pre-start clearance monitoring must 

be conducted during periods of 

visibility sufficient for the lead PSO to 

determine that the shutdown zones 

indicated in table 10 are clear of marine 

mammals. Pile driving and DTH drilling 

may commence following 30 minutes of 

observation when the determination is 

made that the shutdown zones are clear 

of marine mammals; 

• CBS must use soft start techniques 

when impact pile driving. Soft start 

requires contractors to provide an initial 

set of three strikes at reduced energy, 

followed by a 30-second waiting period, 

then two subsequent reduced-energy 

strike sets. A soft start must be 

implemented at the start of each day’s 

impact pile driving and at any time 

following cessation of impact pile 

driving for a period of 30 minutes or 

longer; and 

• If a marine mammal is observed 

entering or within the shutdown zones 

indicated in table 10, pile driving and 

DTH drilling must be delayed or halted. 

If pile driving is delayed or halted due 

to the presence of a marine mammal, the 

activity may not commence or resume 

until either the animal has voluntarily 

exited and been visually confirmed 

beyond the shutdown zone (table 11) or 

15 minutes have passed without redetection of the animal. 

As proposed by the applicant, in 

water activities will take place only 

between civil dawn and civil dusk when 

PSOs can effectively monitor for the 

presence of marine mammals; during 

conditions with a Beaufort sea state of 

4 or less. Pile driving and DTH drilling 

may continue for up to 30 minutes after 

sunset during evening civil twilight, as 

necessary to secure a pile for safety 

prior to demobilization during this time. 

The length of the post-activity 

monitoring period may be reduced if 

darkness precludes visibility of the 

shutdown and monitoring zones. 

Shutdown Zones 

CBS will establish shutdown zones 

for all pile driving and DTH drilling 

activities. The purpose of a shutdown 

zone is generally to define an area 

within which shutdown of the activity 

would occur upon sighting of a marine 

mammal (or in anticipation of an animal 

entering the defined area). Shutdown 

zones would be based upon the Level A 

harassment isopleth for each pile size/ 

type and driving method where 

applicable, as shown in table 10. 

For in-water heavy machinery 

activities other than pile driving, if a 

marine mammal comes within 10 m, 

work will stop and vessels will reduce 

speed to the minimum level required to 

maintain steerage and safe working 

conditions. A 10 m shutdown zone 

serves to protect marine mammals from 

physical interactions with project 

vessels during pile driving and other 

construction activities, such as barge 

positioning or drilling. If an activity is 

delayed or halted due to the presence of 

a marine mammal, the activity may not 

commence or resume until either the 

animal has voluntarily exited and been 

visually confirmed beyond the 

shutdown zone indicated in table 10 or 

15 minutes have passed without redetection of the animal. Construction 

activities must be halted upon 

observation of a species for which 

incidental take is not authorized or a 

species for which incidental take has 

been authorized but the authorized 

number of takes has been met entering 

or within the harassment zone. 

All marine mammals will be 

monitored in the Level B harassment 

zones and throughout the area as far as 

visual monitoring can take place. If a 

marine mammal enters the Level B 

harassment zone, construction activities 

including in-water work will continue 

and the animal’s presence within the 

estimated harassment zone will be 

documented. 

CBS would also establish shutdown 

zones for all marine mammals for which 

take has not been authorized or for 

which incidental take has been 

authorized but the authorized number of 

takes has been met. These zones are 

equivalent to the Level B harassment 

zones for each activity. If a marine 

mammal species not covered under this 

IHA enters the shutdown zone, all inwater activities will cease until the 

animal leaves the zone or has not been 

observed for at least 15 minutes, and 

NMFS will be notified about species 

and precautions taken. Pile driving will 

proceed if the non-IHA species is 

observed to leave the Level B 

harassment zone or if 15 minutes have 

passed since the last observation. 

If shutdown and/or clearance 

procedures would result in an imminent 

safety concern, as determined by CBS or 

its designated officials, the in-water 

activity will be allowed to continue 

until the safety concern has been 

addressed, and the animal will be 

continuously monitored. 

TABLE 10—PROPOSED SHUTDOWN AND MONITORING ZONES

Activity 

Level A isopleth 

(m) Level B 

isopleth 

(m) LF MF HF 2 Phocids 1 Otariids 

Vibratory Pile Removal/Installation 

Phase I: 

16-in temp install ........................................................................................ 10 10 20 10 10 5,415 

16-in temp removal .................................................................................... 10 10 20 10 10 5,415 

16-in perm install ....................................................................................... 10 10 20 10 10 5,415 

24-in perm install ....................................................................................... 10 10 20 10 10 5,415 

Phase II: 

16-in temp install ........................................................................................ 10 10 20 10 10 5,415 

16-in temp removal .................................................................................... 10 10 20 10 10 5,415 

24-in perm install ....................................................................................... 10 10 20 10 10 5,415 

DTH Pile Installation 

Phase I: 

16-in perm install ....................................................................................... 60 10 75 35 10 8,500 


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TABLE 10—PROPOSED SHUTDOWN AND MONITORING ZONES—Continued 

Activity 

Level A isopleth 

(m) Level B 

isopleth 

(m) LF MF HF 2 Phocids 1 Otariids 

24-in perm install ....................................................................................... 570 30 300 125 30 8,500 

Phase II: 

24-in perm install ....................................................................................... 570 30 300 125 30 8,500 

Impact Pile Installation 

Phase I: 

16-in temp install ........................................................................................ 235 10 275 125 10 465

16-in perm install ....................................................................................... 235 10 275 125 10 465 

24-in perm install ....................................................................................... 315 20 300 125 20 1,000 

Phase II: 

16-in temp install ........................................................................................ 235 10 275 125 10 465

24-in perm install ....................................................................................... 315 20 300 125 20 1,000 

1 Maximum shutdown for phocids is reduced to 125 m as they are a common species within the breakwaters of Sitka Sound. 

2 Maximum shutdown for high frequency species is reduced to 300 m, given the difficulty observing harbor porpoise at greater distances. 

Protected Species Observers 

The placement of PSOs during all 

construction activities (described in the 

Proposed Monitoring and Reporting 

section) would ensure that the entire 

shutdown zone is visible. Should 

environmental conditions deteriorate 

such that the entire shutdown zone 

would not be visible (e.g., fog, heavy 

rain), pile driving would be delayed 

until the PSO is confident marine 

mammals within the shutdown zone 

could be detected. 

PSOs would monitor the full 

shutdown zones and the remaining 

Level A harassment and the Level B 

harassment zones to the extent 

practicable. Monitoring zones provide 

utility for observing by establishing 

monitoring protocols for areas adjacent 

to the shutdown zones. Monitoring 

zones enable observers to be aware of 

and communicate the presence of 

marine mammals in the project areas 

outside the shutdown zones and thus 

prepare for a potential cessation of 

activity should the animal enter the 

shutdown zone. 

Pre-Activity Monitoring 

Prior to the start of daily in-water 

construction activity, or whenever a 

break in pile driving or DTH drilling of 

30 minutes or longer occurs, PSOs 

would observe the shutdown and 

monitoring zones for a period of 30 

minutes. The shutdown zone would be 

considered cleared when a marine 

mammal has not been observed within 

the zone for that 30-minute period. If a 

marine mammal is observed within the 

shutdown zones listed in table 10, pile 

driving activity would be delayed or 

halted. If work ceases for more than 30 

minutes, the pre-activity monitoring of 

the shutdown zones would commence. 

A determination that the shutdown zone 

is clear must be made during a period 

of good visibility (i.e., the entire 

shutdown zone and surrounding waters 

must be visible to the naked eye). 

Soft-Start Procedures 

Soft-start procedures provide 

additional protection to marine 

mammals by providing warning and/or 

giving marine mammals a chance to 

leave the area prior to the hammer 

operating at full capacity. For impact 

pile driving, contractors would be 

required to provide an initial set of three 

strikes from the hammer at reduced 

energy, followed by a 30-second waiting 

period, then two subsequent reducedenergy strike sets. Soft-start would be 

implemented at the start of each day’s 

impact pile driving and at any time 

following cessation of impact pile 

driving for a period of 30 minutes or 

longer. 

Based on our evaluation of the 

applicant’s proposed measures NMFS 

has preliminarily determined that the 

proposed mitigation measures provide 

the means of effecting the least 

practicable impact on the affected 

species or stocks and their habitat, 

paying particular attention to rookeries, 

mating grounds, and areas of similar 

significance. 

Proposed Monitoring and Reporting 

In order to issue an IHA for an 

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

MMPA states that NMFS must set forth 

requirements pertaining to the 

monitoring and reporting of such taking. 

The MMPA implementing regulations at 

50 CFR 216.104(a)(13) indicate that 

requests for authorizations must include 

the suggested means of accomplishing 

the necessary monitoring and reporting 

that will result in increased knowledge 

of the species and of the level of taking 

or impacts on populations of marine 

mammals that are expected to be 

present while conducting the activities. 

Effective reporting is critical both to 

compliance as well as ensuring that the 

most value is obtained from the required 

monitoring. 

Monitoring and reporting 

requirements prescribed by NMFS 

should contribute to improved 

understanding of one or more of the 

following: 

• Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density); 

• Nature, scope, or context of likely 

marine mammal exposure to potential 

stressors/impacts (individual or 

cumulative, acute or chronic), through 

better understanding of: (1) action or 

environment (e.g., source 

characterization, propagation, ambient 

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

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

of marine mammal species with the 

activity; or (4) biological or behavioral 

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

feeding areas); 

• Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors; 

• How anticipated responses to 

stressors impact either: (1) long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks; 

• Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat); and, 

• Mitigation and monitoring 

effectiveness. 

Visual Monitoring 

Marine mammal monitoring must be 

conducted in accordance with the 

conditions in this section and the IHA. 


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Marine mammal monitoring during pile 

driving activities would be conducted 

by PSOs meeting NMFS’ following 

requirements: 

• PSOs must be independent of the 

activity contractor (for example, 

employed by a subcontractor) and have 

no other assigned tasks during 

monitoring periods; 

• At least one PSO would have prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization; 

• Other PSOs may substitute 

education (degree in biological science 

or related field) or training for 

experience; and 

• Where a team of three or more PSOs 

is required, a lead observer or 

monitoring coordinator would be 

designated. The lead observer would be 

required to have prior experience 

working as a marine mammal observer 

during construction. 

PSOs should have the following 

additional qualifications: 

Æ Ability to conduct field 

observations and collect data according 

to assigned protocols; 

Æ Experience or training in the field 

identification of marine mammals, 

including the identification of 

behaviors; 

Æ Sufficient training, orientation, or 

experience with the construction 

operation to provide for personal safety 

during observations; 

Æ Writing skills sufficient to prepare 

a report of observations including but 

not limited to the number and species 

of marine mammals observed; dates and 

times when in-water construction 

activities were conducted; dates, times 

and reason for implementation of 

mitigation (or why mitigation was not 

implemented when required); and 

marine mammal behavior; and 

Æ 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. 

• CBS must employ up to five PSOs 

depending on the size of the monitoring 

and shutdown zones. A minimum of 

two PSOs (including the lead PSO) must 

be assigned to the active pile driving 

location to monitor the shutdown zones 

and as much of the Level B harassment 

zones as possible. 

• CBS must establish monitoring 

locations with the best views of 

monitoring zones as described in the 

IHA and Monitoring Plan posted on our 

website. 

• Up to four monitors will be used at 

a time depending on the size of the 

monitoring area. PSOs would be 

deployed in strategic locations around 

the area of potential effects at all times 

during in-water pile driving and 

removal. PSOs will be positioned at 

locations that provide full views of the 

monitoring zones and the Level A 

harassment Shutdown Zones. All PSOs 

would have access to high-quality 

binoculars, range finders to monitor 

distances, and a compass to record 

bearing to animals as well as radios or 

cell phones for maintaining contact with 

work crews. 

• Up to four PSOs will be stationed 

at the following locations: the project 

site, Sandy Beach Day use site, 

O’Connell lightering float, and Whale 

Park. 

Monitoring would be conducted 30 

minutes before, during, and 30 minutes 

after all in water construction activities. 

In addition, PSOs would record all 

incidents of marine mammal 

occurrence, regardless of distance from 

activity, and would document any 

behavioral reactions in concert with 

distance from piles being driven or 

removed. Pile driving activities include 

the time to install or remove a single 

pile or series of piles, as long as the time 

elapsed between uses of the pile driving 

equipment is no more than 30 minutes. 

CBS shall conduct briefings between 

construction supervisors and crews, 

PSOs, CBS staff prior to the start of all 

pile driving activities and when new 

personnel join the work. These briefings 

would explain responsibilities, 

communication procedures, marine 

mammal monitoring protocol, and 

operational procedures. 

Reporting 

A draft marine mammal monitoring 

report will be submitted to NMFS 

within 90 days after the completion of 

pile driving and removal activities for 

each IHA, or 60 days prior to a 

requested date of issuance from any 

future IHAs for projects at the same 

location, whichever comes first. The 

report will include an overall 

description of work completed, a 

narrative regarding marine mammal 

sightings, and associated PSO data 

sheets. Specifically, the report must 

include: 

• 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 drilling) 

and the total equipment duration for 

vibratory removal for each pile or total 

number of strikes for each pile (impact 

driving); 

• PSO locations during marine 

mammal monitoring; 

• Environmental conditions during 

monitoring periods (at beginning and 

end of PSO shift and whenever 

conditions change significantly), 

including Beaufort sea state and any 

other relevant weather conditions 

including cloud cover, fog, sun glare, 

and overall visibility to the horizon, and 

estimated observable distance; 

• Upon observation of a marine 

mammal, the following information: 

• Name of PSO who sighted the 

animal(s) and PSO location and activity 

at the time of sighting; 

• Time of sighting; 

• Identification of the animal(s) (e.g., 

genus/species, lowest possible 

taxonomic level, or unidentifiable), PSO 

confidence in identification, and the 

composition of the group if there is a 

mix of species; 

• Distance and bearing of each marine 

mammal observed relative to the pile 

being driven for each 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 

and shutdown zones; by species; and 

• Detailed information about any 

implementation of any mitigation 

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

description of specific actions that 

ensured, and resulting changes in 

behavior of the animal(s), if any. 

If no comments are received from 

NMFS within 30 days, the draft reports 

will constitute the final reports. If 

comments are received, a final report 

addressing NMFS comments must be 

submitted within 30 days after receipt of 

comments. 

Reporting Injured or Dead Marine 

Mammals 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, the 

IHA-holder must immediately cease the 

specified activities and report the 


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incident to the Office of Protected 

Resources (OPR) 

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

NMFS and to the Alaska Regional 

Stranding Coordinator as soon as 

feasible. If the death or injury was 

clearly caused by the specified activity, 

CBS must immediately cease the 

specified activities until NMFS is able 

to review the circumstances of the 

incident and determine what, if any, 

additional measures are appropriate to 

ensure compliance with the terms of the 

IHA. The IHA-holder must not resume 

their activities until notified by NMFS. 

The report must include the following 

information: 

• 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 discussion of 

our analysis applies to all species listed 

in table 3, given that the anticipated 

effects of this activity on these different 

marine mammal stocks are expected to 

be similar. There is little information 

about the nature or severity of the 

impacts, or the size, status, or structure 

of any of these species or stocks that 

would lead to a different analysis for 

this activity. In addition, because both 

the number and nature of the estimated 

takes anticipated to occur are identical 

in Phase I and II, the analysis below 

applies to both of the IHAs. 

Pile driving and DTH drilling 

activities associated with the project, as 

outlined previously, have the potential 

to disturb or displace marine mammals. 

Specifically, the specified activities may 

result in take, in the form of Level B 

harassment and, for some species, Level 

A harassment from underwater sounds 

generated by pile driving and DTH 

drilling. Potential takes could occur if 

individuals are present in the ensonified 

zone when these activities are 

underway. 

No serious injury or mortality would 

be expected, even in the absence of 

required mitigation measures, given the 

nature of the activities. Further, no take 

by Level A harassment is anticipated for 

killer whales, humpback whales, gray 

whales, or minke whales due to the 

application of planned mitigation 

measures, such as shutdown zones that 

encompass the Level A harassment 

zones for the species, the rarity of the 

species near the action area, and the 

small Level A harassment zones (for 

killer whales only). The potential for 

harassment would be minimized 

through the construction method and 

the implementation of the planned 

mitigation measures (see Proposed 

Mitigation section). 

Take by Level A harassment is 

proposed for three species (harbor 

porpoise, Steller sea lion, and harbor 

seal) as the Level A harassment 

isopleths exceed the size of the 

shutdown zones for specific 

construction scenarios, the Level A 

harassment zones are large, and/or the 

species is frequent near the action area. 

Therefore, there is the possibility that an 

animal could enter a Level A 

harassment zone and remain within that 

zone for a duration long enough to incur 

PTS. Level A harassment of these 

species is therefore proposed for 

authorization. Any take by Level A 

harassment is expected to arise from, at 

most, a small degree of PTS (i.e., minor 

degradation of hearing capabilities 

within regions of hearing that align most 

completely with the energy produced by 

impact pile driving such as the lowfrequency region below 2 kHz), not 

severe hearing impairment or 

impairment within the ranges of greatest 

hearing sensitivity. Animals would need 

to be exposed to higher levels and/or 

longer duration than are expected to 

occur here in order to incur any more 

than a small degree of PTS. 

Further, the amount of take proposed 

for authorization by Level A harassment 

is very low for the marine mammal 

stocks and species. If hearing 

impairment occurs, it is most likely that 

the affected animal would lose only a 

few decibels in its hearing sensitivity. 

Due to the small degree anticipated, any 

PTS potential incurred would not be 

expected to affect the reproductive 

success or survival of any individuals, 

much less result in adverse impacts on 

the species or stock. 

The Level A harassment zones 

identified in table 7 are based upon an 

animal exposed to pile driving or DTH 

drilling of several piles per day (six 

piles per day for vibratory removal and 

installation, four piles per day of impact 

driving, and two piles per day of DTH 

drilling). Given the short duration to 

impact drive or vibratory install or 

remove, or use DTH drilling, each pile 

and break between pile installations (to 

reset equipment and move piles into 

place), an animal would have to remain 

within the area estimated to be 

ensonified above the Level A 

harassment threshold for multiple 

hours. This is highly unlikely given 

marine mammal movement patterns in 

the area. If an animal was exposed to 

accumulated sound energy, the resulting 

PTS would likely be small (e.g., PTS 

onset) at lower frequencies where pile 

driving energy is concentrated, and 

unlikely to result in impacts to 

individual fitness, reproduction, or 

survival. 

Additionally, some subset of the 

individuals that are behaviorally 

harassed could also simultaneously 

incur some small degree of TTS for a 

short duration of time. However, since 

the hearing sensitivity of individuals 

that incur TTS is expected to recover 

completely within minutes to hours, it 

is unlikely that the brief hearing 

impairment would affect the 

individual’s long-term ability to forage 

and communicate with conspecifics, 

and would therefore not likely impact 

reproduction or survival of any 

individual marine mammal, let alone 


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adversely affect rates of recruitment or 

survival of the species or stock. 

The nature of the pile driving project 

precludes the likelihood of serious 

injury or mortality. For all species and 

stocks, take would occur within a 

limited, confined area (adjacent to the 

project site) of the stock’s range. The 

intensity and duration of take by Level 

A and Level B harassment would be 

minimized through use of mitigation 

measures described herein. Further, the 

amount of take proposed to be 

authorized is extremely small when 

compared to stock abundance. 

Behavioral responses of marine 

mammals to pile driving, pile removals, 

and DTH drilling in Sitka Channel and 

the surrounding Sitka Sound are 

expected to be mild, short term, and 

temporary. Marine mammals within the 

Level B harassment zones may not show 

any visual cues they are disturbed by 

activities or they could become alert, 

avoid the area, leave the area, or display 

other mild responses that are not 

observable such as changes in 

vocalization patterns. Given that pile 

driving, pile removal, and DTH drilling 

are temporary activities and effects 

would cease when equipment is not 

operating, any harassment occurring 

would be temporary. Additionally, 

many of the species present in the 

region would only be present 

temporarily based on seasonal patterns 

or during transit between other habitats. 

These species would be exposed to even 

smaller periods of noise-generating 

activity, further decreasing the impacts. 

Nearly all inland waters of southeast 

Alaska, including Sitka Sound, are 

included in the southeast Alaska 

humpback whale feeding BIA (Wild et 

al., 2023), though humpback whale 

distribution in southeast Alaska varies 

by season and waterway (Dahlheim et 

al., 2009). Humpback whales could be 

present within Sitka Sound year round, 

however the action area is within the 

breakwaters where humpback whales 

are not commonly found and therefore, 

the BIA is not expected to be affected. 

Therefore, the proposed project is not 

expected to have significant adverse 

effects on the foraging of humpback 

whales. 

Sitka Sound is also within a gray 

whale migratory corridor BIA (Wild et 

al., 2023). Construction is expected to 

occur while the BIA is active during the 

southbound migration (November to 

January) and northbound migration 

(March–May). The Sound is also a Gray 

whale feeding BIA. Construction is 

expected to overlap with the feeding 

BIA (March–June). However, as noted 

for humpback whales, project activities 

will only overlap seasonally in the gray 

whale migratory and feeding BIAs, and 

the overall 2 year project (Phase I and 

Phase II) is expected to occur over just 

40 in-water workdays, further reducing 

the temporal overlap with the BIAs. 

Additionally, the area of the feeding BIA 

in which impacts of the planned project 

may occur is small relative to both the 

overall area of the BIA and the overall 

area of suitable gray whale habitat 

outside of this BIA. The area of Sitka 

Sound affected by this project is also 

small relative to the rest of the Sound, 

such that it allows animals within the 

migratory corridor to still utilize Sitka 

Sound without necessarily being 

disturbed by the construction. 

Specifically, all Level A harassment 

isopleths for gray whale are within the 

breakwaters where gray whales are not 

expected. Therefore, take of gray whales 

using the feeding and migratory BIAs is 

not expected to impact feeding or 

migratory behavior and, therefore, 

would not impact reproduction or 

survivorship. 

As noted previously, since January 1, 

2019, elevated gray whale strandings 

have occurred along the west coast of 

North America from Mexico through 

Alaska. The event has been declared an 

UME, though a cause has not yet been 

determined. While 6 takes by Level B 

harassment in phase I and 4 takes by 

Level B harassment in phase II of gray 

whale are proposed to be authorized for 

each year this is an extremely small 

portion of the stock (<1 percent), and 

CBS will be required to implement a 

shutdown zone that includes the entire 

Level A harassment zone for lowfrequency cetaceans such as gray 

whales. 

The same regions are also a part of the 

Western DPS Steller sea lion ESA 

critical habitat. While Steller sea lions 

are common in the project area, there 

are no essential physical and biological 

habitat features, such as haulouts or 

rookeries, within the proposed project 

area. The nearest haulout is 

approximately 25 km away from the 

proposed project area. Therefore, the 

proposed project is not expected to have 

significant adverse effects on the critical 

habitat of Western DPS Steller sea lions. 

No areas of specific biological 

importance (e.g., ESA critical habitat, 

other BIAs, or other areas) for any other 

species are known to co-occur with the 

project area. 

In addition, it is unlikely that minor 

noise effects in a small, localized area of 

habitat would have any effect on each 

stock’s ability to recover. In 

combination, we believe that these 

factors, as well as the available body of 

evidence from other similar activities, 

demonstrate that the potential effects of 

the specified activities would have only 

minor, short-term effects on individuals. 

The specified activities are not expected 

to impact rates of recruitment or 

survival and would therefore not result 

in population-level impacts. 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from this activity are 

not expected to adversely affect any of 

the species or stocks through effects on 

annual rates of recruitment or survival: 

• No serious injury or mortality is 

anticipated or authorized; 

• Level A harassment would be very 

small amounts and of low degree; 

• Level A harassment takes of only 

harbor porpoise, Steller sea lions and 

harbor seals; 

• For all species, the Sitka Sound and 

channel are a very small and peripheral 

part of their range; 

• Anticipated takes by Level B 

harassment are relatively low for all 

stocks. Level B harassment would be 

primarily in the form of behavioral 

disturbance, resulting in avoidance of 

the project areas around where impact 

or vibratory pile driving is occurring, 

with some low-level TTS that may limit 

the detection of acoustic cues for 

relatively brief amounts of time in 

relatively confined footprints of the 

activities; 

• Effects on species that serve as prey 

for marine mammals from the activities 

are expected to be short-term and, 

therefore, any associated impacts on 

marine mammal feeding are not 

expected to result in significant or longterm consequences for individuals, or to 

accrue to adverse impacts on their 

populations; 

• The ensonified areas are very small 

relative to the overall habitat ranges of 

all species and stocks, and would not 

adversely affect ESA-designated critical 

habitat for any species or any areas of 

known biological importance; 

• The lack of anticipated significant 

or long-term negative effects to marine 

mammal habitat; and 

• CBS would implement mitigation 

measures including soft-starts and 

shutdown zones to minimize the 

numbers of marine mammals exposed to 

injurious levels of sound, and to ensure 

that take by Level A harassment is, at 

most, a small degree of PTS. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

proposed monitoring and mitigation 

measures, NMFS preliminarily finds 

that the total marine mammal take, 

specific to each of the 2 consecutive 


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years of proposed activity, would have 

a negligible impact on all affected 

marine mammal species or stocks. 

Small Numbers 

As noted previously, only take of 

small numbers of marine mammals may 

be authorized under sections 

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

specified activities other than military 

readiness activities. The MMPA does 

not define small numbers and so, in 

practice, where estimated numbers are 

available, NMFS compares the number 

of individuals taken to the most 

appropriate estimation of abundance of 

the relevant species or stock in our 

determination of whether an 

authorization is limited to small 

numbers of marine mammals. When the 

predicted number of individuals to be 

taken is fewer than one-third of the 

species or stock abundance, the take is 

considered to be of small numbers. 

Additionally, other qualitative factors 

may be considered in the analysis, such 

as the temporal or spatial scale of the 

activities. 

The amount of take NMFS proposes to 

authorize, for each of the 2 consecutive 

years of proposed activity, is below one 

third of the estimated stock abundance 

for all species (in fact, take of 

individuals is less than 2 percent of the 

abundance of the affected stocks, see 

table 9). This is likely a conservative 

estimate because we assume all takes 

are of different individual animals, 

which is likely not the case. Some 

individuals may return multiple times 

in a day, but PSOs would count them as 

separate takes if they cannot be 

individually identified. 

There is no current or historical 

estimate of the Alaska minke whale 

stock, but there are known to be over 

1,000 minke whales in the Gulf of 

Alaska (Muto et al. 2018), so the 10 

takes by Level B harassment proposed 

over the 2 years of the project duration 

is small relative to estimated survey 

abundance, even if each take occurred 

to a new individual. Additionally, the 

range of the Alaska stock of minke 

whales is extensive, stretching from the 

Canadian Pacific coast to the Chukchi 

Sea, and CBS’s project would only 

impact a small portion of this range. 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the 

anticipated take of marine mammals, 

NMFS preliminarily finds that, specific 

to each of the two consecutive years of 

proposed activity, small numbers of 

marine mammals would be taken 

relative to the population size of the 

affected species or stocks. 

Unmitigable Adverse Impact Analysis 

and Determination 

In order to issue an IHA, NMFS must 

find that the specified activity will not 

have an ‘‘unmitigable adverse impact’’ 

on the subsistence uses of the affected 

marine mammal species or stocks by 

Alaskan Natives. NMFS has defined 

‘‘unmitigable adverse impact’’ in 50 CFR 

216.103 as an impact resulting from the 

specified activity: (1) That is likely to 

reduce the availability of the species to 

a level insufficient for a harvest to meet 

subsistence needs by: (i) Causing the 

marine mammals to abandon or avoid 

hunting areas; (ii) Directly displacing 

subsistence users; or (iii) Placing 

physical barriers between the marine 

mammals and the subsistence hunters; 

and (2) That cannot be sufficiently 

mitigated by other measures to increase 

the availability of marine mammals to 

allow subsistence needs to be met. 

Sitka Channel and other nearby areas 

are within the traditional territory of the 

Sheet’ka ́ wa ́an. Alaska natives have 

traditionally harvested marine mammals 

in Sitka, however today a majority of the 

subsistence harvest is of species other 

than marine mammals. Alaska 

Department Fish and Game reported 

that in 2013, around 11 percent of Sitka 

households used subsistence-caught 

marine mammals (ADF&G, 2023), 

however this is the most recent data 

available and there has not been a 

survey since. 

The proposed project is not likely to 

adversely impact the availability of any 

marine mammal species or stocks that 

are commonly used for subsistence 

purposes or impact subsistence harvest 

of marine mammals in the region 

because: 

• There is no recent recorded 

subsistence harvest of marine mammals 

in the area; 

• Construction activities are 

temporary and localized primarily 

within Sitka Channel; 

• Construction will not take place 

during the herring spawning season 

when subsistence species are more 

active; 

• Mitigation measures will be 

implemented to minimize disturbance 

of marine mammals in the action area; 

and, 

• The project will not result in 

significant changes to availability of 

subsistence resources. 

Based on the description of the 

specified activity, the measures 

described to minimize adverse effects 

on the availability of marine mammals 

for subsistence purposes, and the 

proposed mitigation and monitoring 

measures; NMFS has preliminarily 

determined that, specific to each of the 

two consecutive years of proposed 

activity, there will not be an 

unmitigable adverse impact on 

subsistence uses from CBS’s proposed 

activities. 

Endangered Species Act 

Section 7(a)(2) of the Endangered 

Species Act of 1973 (ESA; 16 U.S.C. 

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

IHAs, NMFS Office of Protected 

Resources (OPR) consults internally 

whenever we propose to authorize take 

for endangered or threatened species, in 

this case with the NMFS Alaska 

Regional Office (AKR). 

NMFS OPR has requested initiation of 

section 7 consultation with the NMFS 

AKR for the issuance of this IHA. NMFS 

will conclude the ESA consultation 

prior to reaching a determination 

regarding the proposed issuance of the 

authorization. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

two sequential IHAs, each lasting 1 year, 

to CBS for conducting Seaplane Base 

construction in Sitka, Alaska, starting in 

July 2024 for Phase I and July 2025 for 

Phase II, provided the previously 

mentioned mitigation, monitoring, and 

reporting requirements are incorporated. 

Drafts of the proposed IHAs can be 

found at: https://

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/incidentaltake-authorizations-constructionactivities. 

Request for Public Comments 

We request comment on our analyses, 

the proposed authorization, and any 

other aspect of this notice of proposed 

IHAs for the proposed construction 

project. We also request comment on the 

potential renewal of these proposed 

IHAs as described in the paragraph 

below. Please include with your 

comments any supporting data or 

literature citations to help inform 

decisions on the request for these IHAs 

or subsequent renewal IHAs. 

On a case-by-case basis, NMFS may 

issue a one-time, 1-year renewal IHA 

following notice to the public providing 

an additional 15 days for public 

comments when (1) up to another year 

of identical or nearly identical activities 


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as described in the Description of 

Proposed Activity section of this notice 

is planned or (2) the activities as 

described in the Description of 

Proposed Activity section of this notice 

would not be completed by the time the 

IHA expires and a renewal would allow 

for completion of the activities beyond 

that described in the Dates and Duration 

section of this notice, provided all of the 

following conditions are met: 

• A request for renewal is received no 

later than 60 days prior to the needed 

renewal IHA effective date (recognizing 

that the renewal IHA expiration date 

cannot extend beyond one year from 

expiration of the initial IHA). 

• The request for renewal must 

include the following: 

(1) An explanation that the activities 

to be conducted under the requested 

renewal IHA are identical to the 

activities analyzed under the initial 

IHA, are a subset of the activities, or 

include changes so minor (e.g., 

reduction in pile size) that the changes 

do not affect the previous analyses, 

mitigation and monitoring 

requirements, or take estimates (with 

the exception of reducing the type or 

amount of take). 

(2) A preliminary monitoring report 

showing the results of the required 

monitoring to date and an explanation 

showing that the monitoring results do 

not indicate impacts of a scale or nature 

not previously analyzed or authorized. 

Upon review of the request for 

renewal, the status of the affected 

species or stocks, and any other 

pertinent information, NMFS 

determines that there are no more than 

minor changes in the activities, the 

mitigation and monitoring measures 

will remain the same and appropriate, 

and the findings in the initial IHA 

remain valid. 

Dated: January 5, 2024. 

Kimberly Damon-Randall, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2024–00390 Filed 1–10–24; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XD640] 

Taking and Importing Marine 

Mammals; Taking Marine Mammals 

Incidental to Geophysical Surveys 

Related to Oil and Gas Activities in the 

Gulf of Mexico 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice of issuance of Letter of 

Authorization. 

SUMMARY: In accordance with the 

Marine Mammal Protection Act 

(MMPA), as amended, its implementing 

regulations, and NMFS’ MMPA 

Regulations for Taking Marine 

Mammals Incidental to Geophysical 

Surveys Related to Oil and Gas 

Activities in the Gulf of Mexico, 

notification is hereby given that a Letter 

of Authorization (LOA) has been issued 

to Chevron U.S.A. Inc. (Chevron) for the 

take of marine mammals incidental to 

geophysical survey activity in the Gulf 

of Mexico. 

DATES: The LOA is effective from 

January 5, 2024 through February 19, 

2024. 

ADDRESSES: The LOA, LOA request, and 

supporting documentation are available 

online at: https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-gulf-mexico. In case of problems 

accessing these documents, please call 

the contact listed below (see FOR

FURTHER INFORMATION CONTACT). 

FOR FURTHER INFORMATION CONTACT: 

Jenna Harlacher, Office of Protected 

Resources, NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 

Background 

Sections 101(a)(5)(A) and (D) of the 

MMPA (16 U.S.C. 1361 et seq.) direct 

the Secretary of Commerce 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 

issued or, if the taking is limited to 

harassment, a notice of a proposed 

authorization is provided to the public 

for review. 

An authorization for incidental 

takings shall be granted if NMFS finds 

that the taking will have a negligible 

impact on the species or stock(s), will 

not have an unmitigable adverse impact 

on the availability of the species or 

stock(s) for subsistence uses (where 

relevant), and if the permissible 

methods of taking and requirements 

pertaining to the mitigation, monitoring 

and reporting of such takings are set 

forth. NMFS has defined ‘‘negligible 

impact’’ in 50 CFR 216.103 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. 

Except with respect to certain 

activities not pertinent here, 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). 

On January 19, 2021, we issued a final 

rule with regulations to govern the 

unintentional taking of marine 

mammals incidental to geophysical 

survey activities conducted by oil and 

gas industry operators, and those 

persons authorized to conduct activities 

on their behalf (collectively ‘‘industry 

operators’’), in U.S. waters of the Gulf of 

Mexico (GOM) over the course of 5 

years (86 FR 5322, January 19, 2021). 

The rule was based on our findings that 

the total taking from the specified 

activities over the 5-year period will 

have a negligible impact on the affected 

species or stock(s) of marine mammals 

and will not have an unmitigable 

adverse impact on the availability of 

those species or stocks for subsistence 

uses. The rule became effective on April 

19, 2021. 

Our regulations at 50 CFR 217.180 et 

seq. allow for the issuance of LOAs to 

industry operators for the incidental 

take of marine mammals during 

geophysical survey activities and 

prescribe the permissible methods of 

taking and other means of effecting the 

least practicable adverse impact on 

marine mammal species or stocks and 

their habitat (often referred to as 

mitigation), as well as requirements 

pertaining to the monitoring and 

reporting of such taking. Under 50 CFR 

217.186(e), issuance of an LOA shall be 

based on a determination that the level 

of taking will be consistent with the 

findings made for the total taking 

allowable under these regulations and a 

determination that the amount of take 

authorized under the LOA is of no more 

than small numbers. 

Summary of Request and Analysis 

This LOA covers work that was not 

completed under Chevron’s 2023 LOA 

that expired on January 2, 2024 (88 FR 

40209, June 21, 2023). Chevron 

requested an additional LOA covering 

26 days of work. There are no other 

changes from the previously analyzed 

and issued LOA (88 FR 40209, June 21, 

2023) other than a reduction in the 


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