Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 34203 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XB089] 

Taking of Marine Mammals Incidental 

to Specific Activities; Taking of Marine 

Mammals Incidental to Pile Driving and 

Removal Activities During the 

Metlakatla Seaplane Facility 

Refurbishment Project, Metlakatla, 

Alaska 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorization; request for 

comments on proposed authorization 

and possible renewal. 

SUMMARY: NMFS has received a request 

from the Alaska Department of 

Transportation and Public Facilities 

(AKDOT&PF) for authorization to take 

marine mammals incidental to pile 

driving/removal and down-the-hole 

drilling (DTH) activities during 

maintenance improvements to the 

existing Metlakatla Seaplane Facility 

(MSF) in Southeast Alaska. Pursuant to 

the Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue an incidental 

harassment authorization (IHA) to 

incidentally take marine mammals 

during the specified activities. NMFS is 

also requesting comments on a possible 

one-year renewal 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 July 29, 2021. 

ADDRESSES: Comments should be 

addressed to Jolie Harrison, Chief, 

Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service and should be 

sent by electronic mail to ITP.Egger@

noaa.gov. 

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 must not exceed a 

25-megabyte file size, including all 

attachments. All comments received are 

a part of the public record and will 

generally be posted online at https://

www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act without 

change. All personal identifying 

information (e.g., name, address) 

voluntarily submitted by the commenter 

may be publicly accessible. Do not 

submit confidential business 

information or otherwise sensitive or 

protected information. 

FOR FURTHER INFORMATION CONTACT: 

Stephanie Egger, Office of Protected 

Resources, NMFS, (301) 427–8401. 

Electronic copies of the application and 

supporting documents, as well as a list 

of the references cited in this document, 

may be obtained online at: https://

www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act. In case 

of problems accessing these documents, 

or for anyone who is unable to comment 

via electronic mail, please call the 

contact listed above. 

SUPPLEMENTARY INFORMATION: 

Background 

The MMPA prohibits the ‘‘take’’ of 

marine mammals, with certain 

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

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

seq.) direct the Secretary of Commerce 

(as delegated to NMFS) to allow, upon 

request, the incidental, but not 

intentional, taking of small numbers of 

marine mammals by U.S. citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

issued or, if the taking is limited to 

harassment, a notice of a proposed 

incidental take authorization may be 

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 such 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 such takings are set 

forth. The definitions of all applicable 

MMPA statutory terms cited above are 

included in the relevant sections below. 

National Environmental Policy Act 

To comply with the National 

Environmental Policy Act of 1969 

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

NOAA Administrative Order (NAO) 

216–6A, NMFS must review our 

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

IHA) with respect to potential impacts 

on the human environment. This action 

is consistent with categories of activities 

identified in Categorical Exclusion B4 

(IHAs with no anticipated serious injury 

or mortality) of the Companion Manual 

for NOAA Administrative Order 216– 

6A, which do not individually or 

cumulatively have the potential for 

significant impacts on the quality of the 

human environment and for which we 

have not identified any extraordinary 

circumstances that would preclude this 

categorical exclusion. Accordingly, 

NMFS has preliminarily determined 

that the issuance of the proposed IHA 

qualifies to be categorically excluded 

from further NEPA review. 

We will review all comments 

submitted in response to this notice 

prior to concluding our NEPA process 

or making a final decision on the IHA 

request. 

Summary of Request 

On August 10, 2020, NMFS received 

a request from the AKDOT&PF for an 

IHA to take marine mammals incidental 

to pile driving/removal and DTH 

activities during maintenance 

improvements to the existing MSF in 

Southeast Alaska. The application was 

deemed adequate and complete on 

November 23, 2020. The applicant also 

provided an addendum to their 

application on February 23, 2021 for the 

addition of eight piles, some changes to 

their proposed shutdown zones, and 

minor changes to their take estimates 

due to the increase of in-water work 

days from the eight additional piles. The 

applicant’s request is for take of eight 

species of marine mammals by Level B 

harassment only. Neither the 

AKDOT&PF nor NMFS expects serious 

injury or mortality to result from this 

activity and, therefore, an IHA is 

appropriate. 

Description of Proposed Activity 

Overview 

The purpose of this project is to make 

repairs to the MSF. The existing facility 

has experienced deterioration in recent 

years and AKDOT&PF has conducted 

several repair projects. The facility is 

near the end of its useful life, and 

replacement of all the existing float 

structures is required to continue safe 

operation in the future. 


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34204 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 

Dates and Duration 

The applicant is requesting an IHA to 

conduct pile driving/removal and DTH 

over two months (approximately 26 

working days) beginning in August 

2021. Pile installation and removal will 

be intermittent during this period, 

depending on weather, construction and 

mechanical delays, protected species 

shutdowns, and other potential delays 

and logistical constraints. Pile 

installation will occur intermittently 

during the work period, for durations of 

minutes to hours at a time. 

Approximately 18 days of pile 

installation and 8 days of pile removal 

will occur using vibratory and impact 

pile driving and some DTH to stabilize 

the piles. These are discussed in further 

detail below. The total construction 

duration accounts for the time required 

to mobilize materials and resources and 

construct the project. 

Specific Geographic Region 

The proposed project in Metlakatla is 

located approximately 24 kilometers 

(km) (15 miles (mi)) south of Ketchikan, 

in Southeast Alaska. Metlakatla, is on 

Annette Island, in the Prince of WhalesHyder Census Area of Southeast Alaska. 

The Metlakatla Seaplane Facility is 

centrally located in the village of 

Metlakatla on the south shore of Port 

Chester (Figure 1) within Section 5, 

Township 78 South, Range 92 East of 

the Copper River Meridian; United 

States Geological Survey Quad Map 

Ketchikan A–5; Latitude 55°7′50.30′′ 

North, 131°34′28.08′′ West. 

Port Chester is a bay located on the 

east shore of Nichols Passage and on the 

west side of Annette Island. Port Chester 

contains numerous small islands and 

reefs. The bay is one of many that lead 

to a larger system of glacial fjords 

connecting various channels with the 

open ocean via Nichol’s Passage, 

Clarence Strait, and Dixon Entrance. 

Port Chester is generally characterized 

by semidiurnal tides with mean tidal 

ranges of more than 5 meters (m) (16 

feet (ft)). Freshwater inputs to Port 

Chester originate from Trout Lake, 

Melanson Lake, Chester Lake, and other 

minor drainages from Annette Island. 

Three anadromous streams terminate in 

Port Chester: Hemlock Creek, Trout 

Lake Creek, and an unnamed creek that 

originates from Melanson Lake (Giefer 

and Blossom 2020). The bathymetry of 

the bay is variable depending on 

location and proximity to shore, islands, 

or rocks. Depths approach 107 to 122 m 

(350 to 400 ft) on the west side of the 

bay near Nichols Passage. Nichols 

Passage is a wide and deep channel that 

runs between Gravina Island and 

Annette Island. Depths can exceed 305 

m (1,000 ft) towards the south end of the 

channel. 

BILLING CODE 3510–22–P 


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Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 34205 

BILLING CODE 3510–22–C 

Detailed Description of Specific Activity 

Proposed activities included as part of 

the project with potential to affect 

marine mammals include the noise 

generated by vibratory removal of steel 

pipe piles, vibratory and impact 

installation of steel pipe piles, and DTH 

to stabilize piles. Pile removal will be 

conducted using a vibratory hammer. 

Pile installation will be conducted using 

both a vibratory and impact hammer 

and DTH pile installation methods. 

Piles will be advanced to refusal using 

a vibratory hammer. After DTH pile 

installation, the final approximately 10 

ft of driving will be conducted using an 

impact hammer so that the structural 

capacity of the pile embedment can be 

verified. The pile installation methods 

used will depend on sediment depth 

and conditions at each pile location. 

Pile installation and removal will occur 

in waters approximately 6–7 m (20–23 

ft) in depth. 

The project will involve the removal 

of 11 existing steel pipe piles (16-inch 

(in) diameter) that support the existing 

multiple-float structure. The multiplefloat timber structure, which covers 

8,600 square ft, will also be removed. A 

new 4,800-square-ft single-float timber 

structure will be installed in the same 

general location. Six 24-in diameter 

steel pipe piles will be installed to act 

as restraints for the new seaplane float. 

In addition, 12 temporary 24-in steel 

piles will be installed to support pile 

installation and removed following 

completion of construction. 


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~~ MetlakaUa Saaptana Faclmy 

Ratucblallma1H Project 

Figure 1--Project Location, Metlakatla, Alaska 
34206 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 

DTH pile installation involves drilling 

rock sockets into the bedrock to support 

installation of the 6 permanent piles and 

12 temporary piles. Rock sockets consist 

of inserting the pile in a drilled hole 

into the underlying bedrock after the 

pile has been driven through the 

overlying softer sediments to refusal by 

vibratory or impact methods. The pile is 

advanced farther into this drilled hole to 

properly secure the bottom portion of 

the pile into the rock. The depth of the 

rock socket varies, but 10–15 ft is 

commonly required. The diameter of the 

rock socket is slightly larger than the 

pile being driven. Rock sockets are 

constructed using a DTH device with 

both rotary and percussion-type actions. 

Each device consists of a drill bit that 

drills through the bedrock using both 

rotary and pulse impact mechanisms. 

This breaks up the rock to allow 

removal of the fragments and insertion 

of the pile. The pile is usually advanced 

at the same time that drilling occurs. 

Drill cuttings are expelled from the top 

of the pile using compressed air. It is 

estimated that drilling rock sockets into 

the bedrock will take about 1–3 hours 

(hrs) per pile. Tension anchors will be 

installed in each of the six permanent 

piles. Tension anchors are installed 

within piles that are drilled into the 

bedrock below the elevation of the pile 

tip after the pile has been driven 

through the sediment layer to refusal. A 

6- or 8-in diameter steel pipe casing will 

be inserted inside the larger diameter 

production pile. A rock drill will be 

inserted into the casing, and a 6- to 8- 

in diameter hole will be drilled into 

bedrock with rotary and percussion 

drilling methods. The drilling work is 

contained within the steel pile casing 

and the steel pipe pile. The typical 

depth of the drilled hole varies, but 20– 

30 ft is common. Rock fragments will be 

removed through the top of the casing 

with compressed air. A steel rod will 

then be grouted into the drilled hole and 

affixed to the top of the pile. The 

purpose of a tension anchor is to secure 

the pile to the bedrock to withstand 

uplift forces. It is estimated that tension 

anchor installation will take about 1–2 

hrs per pile. 

No concurrent pile driving is 

anticipated for this project. 

Please see Table 1 below for the 

specific amount of time required to 

install and remove piles. 

TABLE 1—PILE DRIVING AND REMOVAL ACTIVITIES

Pile diameter and type 

Number 

of 

piles 

Rock 

sockets 

Tension 

anchors 

Impact 

strikes per 

pile 

(duration in 

minutes) 

Vibratory 

duration 

per pile 

(minutes) 

DTH pile 

installation 

(rock socket) 

duration per 

pile 

(minutes) 

DTH pile 

installation 

(tension anchor) duration 

per pile 

(minutes) 

Total 

duration of 

activity 

per pile 

(hours) 

Piles per 

day 

(range) 

Total 

days 

Pile Installation 

24-in Steel Plumb Piles 

(Permanent) ..................... 4 4 4 20 (15) 15 180 120 5.5 0.5 (0–1) 8 

24-in Steel Batter Piles 

(Permanent) ..................... 2 2 2 20 (15) 15 90 120 4 0.5 (0–1) 4 

24-in Steel Piles (Temporary) ............................. 12 12 0 20 (15) 15 60 N/A 1.5 2 (1–3) 6 

Pile Removal 

16-in Steel Piles .................. 11 N/A N/A N/A 30 N/A N/A 0.5 3 (2–4) 4 

24-in Steel Piles (Temporary) ............................. 12 N/A N/A N/A 30 N/A N/A 0.5 3 (2–4) 4 

Totals ........................... 29 18 6 N/A N/A N/A N/A N/A N/A 26 

Note: DTH = down-the-hole; N/A = not applicable. 

Proposed mitigation, monitoring, and 

reporting measures are described in 

detail later in this document (please see 

Proposed Mitigation and Proposed 

Monitoring and Reporting). 

Description of Marine Mammals in the 

Area of Specified Activities 

Sections 3 and 4 of the application 

summarize available information 

regarding status and trends, distribution 

and habitat preferences, and behavior 

and life history, of the potentially 

affected species. 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/marinemammal-stock-assessment-reports) and 

more general information about these 

species (e.g., physical and behavioral 

descriptions) may be found on NMFS’s 

website (https://www.fisheries.noaa. 

gov/find-species). 

Table 2 lists all species or stocks for 

which take is expected and proposed to 

be authorized for this action, 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. For taxonomy, we follow 

Committee on Taxonomy (2020). 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 

mortality is anticipated or authorized 

here, PBR and annual serious injury and 

mortality from anthropogenic sources 

are included here as gross indicators of 

the status of the species and other 

threats. 

Marine mammal abundance estimates 

presented in this document represent 

the total number of individuals that 

make up a given stock or the total 

number estimated within a particular 

study or survey area. NMFS’ stock 

abundance estimates for most species 

represent the total estimate of 

individuals within the geographic area, 

if known, that comprises that stock. For 

some species, this geographic area may 

extend beyond U.S. waters. All managed 

stocks in this region are assessed in 

NMFS’ U.S. Pacific and Alaska SARs 

(Carretta et al., 2020; Muto et al., 2020). 

All MMPA stock information presented 

in Table 2 is the most recent available 

at the time of publication and is 

available in the 2019 SARs (Caretta et 

al., 2020; Muto et al., 2020) and draft 

2020 SARs (available online at: 

www.fisheries.noaa.gov/national/ 

marine-mammal-protection/draftmarine-mammal-stock-assessmentreports). 


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TABLE 2—MARINE MAMMAL OCCURRENCE IN THE PROJECT AREA

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): 

Minke Whale .................. Balaenoptera acutorostrata .. Alaska ................................... -, -, N N/A (see SAR, N/A, see 

SAR).

UND 0 

Humpback Whale ........... Megaptera novaeangliae ...... Central N Pacific .................. -, -, Y 10,103 (0.3, 7,891, 2006) .... 83 26 

Superfamily Odontoceti (toothed whales, dolphins, and porpoises) 

Family Delphinidae: 

Killer Whale .................... Orcinus orca ......................... Alaska Resident ................... -, -, N 2,347 (N/A, 2347, 2012) ...... 24 1 

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

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

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

Family Phocoenidae (porpoises): 

Dall’s Porpoise ............... Phocoenoides dalli ............... AK ......................................... -, -, N 83,400 (0.097, N/A, 1991) ... UND 38 

Harbor Porpoise ............. Phocoena phocoena ............ Southeast Alaska Inland 

waters.

-, -, Y see SAR (see SAR, see 

SAR, 2012).

see SAR 34 

Order Carnivora—Superfamily Pinnipedia 

Family Otariidae (eared seals 

and sea lions): 

Steller sea lion ............... Eumetopias jubatus .............. Eastern DPS ........................ T, D, Y 43,201 a (see SAR, 43,201, 

2017).

2592 112 

Family Phocidae (earless 

seals): 

Harbor Seal .................... Phoca vitulina ....................... Clarence Strait ..................... -, -, N 27,659 (see SAR, 24,854, 

2015).

746 40 

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-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable [explain if this is the case]: 3These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated 

mortality due to commercial fisheries is presented in some cases. 

As indicated above, all eight species 

(with 10 managed stocks) in Table 2 

temporally and spatially co-occur with 

the activity to the degree that take is 

reasonably likely to occur, and we have 

proposed authorizing it. 

Minke Whale 

In the North Pacific Ocean, minke 

whales occur from the Bering and 

Chukchi seas south to near the Equator 

(Leatherwood et al., 1982). In the 

northern part of their range, minke 

whales are believed to be migratory, 

whereas, they appear to establish home 

ranges in the inland waters of 

Washington and along central California 

(Dorsey et al. 1990). Minke whales are 

observed in Alaska’s nearshore waters 

during the summer months (National 

Park Service (NPS) 2018). Minke whales 

are usually sighted individually or in 

small groups of 2–3, but there are 

reports of loose aggregations of 

hundreds of animals (NMFS 2018d). 

No abundance estimates have been 

made for the number of minke whales 

in the entire North Pacific. However, 

some information is available on the 

numbers of minke whales in some areas 

of Alaska. Line-transect surveys were 

conducted in shelf and nearshore waters 

(within 30–45 nautical mi of land) in 

2001–2003 from the Kenai Fjords in the 

Gulf of Alaska to the central Aleutian 

Islands. Minke whale abundance was 

estimated to be 1,233 (CV = 0.34) for 

this area (Zerbini et al., 2006). This 

estimate has also not been corrected for 

animals missed on the trackline. The 

majority of the sightings were in the 

Aleutian Islands, rather than in the Gulf 

of Alaska, and in water shallower than 

200 m. So few minke whales were seen 

during three offshore Gulf of Alaska 

surveys for cetaceans in 2009, 2013, and 

2015 that a population estimate for this 

species in this area could not be 

determined (Rone et al., 2017). 

Anecdotal observations suggest that 

minke whales do not enter Port Chester, 

and so are expected to occur rarely in 

the project area (L. Bethel, personal 

communication, June 11, 2020 as cited 

in the application). In nearby Tongass 

Narrows, NMFS estimated an 

occurrence rate of three individuals 

every 4 months (85 FR 673) based on 

Freitag, 2017 (as cited in 83 FR 37473). 

A recent monitoring report for Tongass 

Narrows reported no sightings of minke 

whales in May 2021 (report available at 

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

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). 

Humpback Whale 

The humpback whale is distributed 

worldwide in all ocean basins and a 

broad geographical range from tropical 

to temperate waters in the Northern 

Hemisphere and from tropical to nearice-edge waters in the Southern 

Hemisphere. The humpback whales that 

forage throughout British Colombia and 

Southeast Alaska undertake seasonal 

migrations from their tropical calving 

and breeding grounds in winter to their 

high-latitude feeding grounds in 

summer. They may be seen at any time 


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34208 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 

of year in Alaska, but most animals 

winter in temperate or tropical waters 

near Hawaii. In the spring, the animals 

migrate back to Alaska where food is 

abundant. The Central North Pacific 

stock of humpback whales are found in 

the waters of Southeast Alaska and 

consist of two distinct population 

segments (DPSs), the Hawaii DPS and 

the Mexico DPS (Mexico DPS listed 

under the ESA as threatened). 

Within Southeast Alaska, humpback 

whales are found throughout all major 

waterways and in a variety of habitats, 

including open-ocean entrances, openstrait environments, near-shore waters, 

area with strong tidal currents, and 

secluded bays and inlets. They tend to 

concentrate in several areas, including 

northern Southeast Alaska. Patterns of 

occurrence likely follow the spatial and 

temporal changes in prey abundance 

and distribution with humpback whales 

adjusting their foraging locations to 

areas of high prey density (Clapham 

2000). While many humpback whales 

migrate to tropical calving and breeding 

grounds in winter, they have been 

observed in Southeast Alaska in all 

months of the year (Bettridge et al., 

2015). 

No systematic studies have 

documented humpback whale 

abundance near Metlakatla. Anecdotal 

information from Metlakatla and 

Ketchikan suggest that humpback 

whales’ utilization of the area is 

intermittent year-round. Their 

abundance, distribution, and occurrence 

are dependent on and fluctuate with 

fish prey. Local mariners estimate that 

one to two humpback whales may be 

present in the Port Chester area on a 

daily basis during summer months (L. 

Bethel, personal communication, June 

11, 2020 as cited in the application). 

This is consistent with reports from 

nearby Tongass Narrows, which suggest 

that humpback whales occur alone or in 

groups of two or three individuals about 

once a week (Freitag 2017 as cited in 

85 FR 673). Therefore, in nearby 

Tongass Narrows, NMFS estimated that 

approximately four humpback whales 

may transit through each week (85 FR 

673). A recent monitoring report for 

Tongass Narrows reported 9 individual 

sightings of humpback whales with 6 

Level B harassment takes of humpback 

whales in May 2021(report available at 

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

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). Anecdotal reports 

suggest that humpback whale 

abundance is higher and occurrence is 

more regular in Metlakatla. 

On April 21, 2021, a final rule 

designating critical habitat for 

humpback whales was published in the 

Federal Register (86 FR 21082), 

however, no critical habitat for Mexico 

DPS humpback whales is within or near 

the project area. 

Killer Whale 

Killer whales have been observed in 

all oceans and seas of the world, but the 

highest densities occur in colder and 

more productive waters found at high 

latitudes. Killer whales are found 

throughout the North Pacific and occur 

along the entire Alaska coast, in British 

Columbia and Washington inland 

waterways, and along the outer coasts of 

Washington, Oregon, and California 

(NMFS 2018f). 

The Alaska Resident stock occurs 

from Southeast Alaska to the Aleutian 

Islands and Bering Sea. The Northern 

Resident stock occurs from Washington 

State through part of Southeast Alaska; 

and the West Coast Transient stock 

occurs from California through 

Southeast Alaska (Muto et al., 2018) and 

are thought to occur frequently in 

Southeast Alaska (Straley 2017). 

Transient killer whales hunt and feed 

primarily on marine mammals, while 

residents forage primarily on fish. 

Transient killer whales feed primarily 

on harbor seals, Dall’s porpoises, harbor 

porpoises, and sea lions. Resident killer 

whale populations in the eastern North 

Pacific feed mainly on salmonids, 

showing a strong preference for Chinook 

salmon (NMFS 2016a). 

No systematic studies of killer whales 

have been conducted in or around Port 

Chester. Dahlheim et al. (2009) observed 

transient killer whales within Lynn 

Canal, Icy Strait, Stephens Passage, 

Frederick Sound, and upper Chatham 

Strait. Anecdotal local information 

suggests that killer whales are rarely 

seen within the Port Chester area, but 

may be present more frequently in 

Nichols Passage and other areas around 

Gravina Island (L. Bethel, personal 

communication, June 11, 2020 as cited 

in the application). In nearby Tongass 

Narrows, NMFS estimated that one pod 

of 12 killer whales may be present each 

month, and two pods of 12 animals 

during May, June, and July based on 

killer whales generally just transiting 

through Tongass Narrows, and not 

lingering in the project area. Killer 

whales are observed on average about 

once every 2 weeks, and abundance 

increases between May and July (as 

cited in Freitag 2017 in 85 FR 673). A 

recent monitoring report for Tongass 

Narrows reported 10 individuals sighted 

and 10 Level B harassment takes of 

killer whales during May 2021 (report 

available at https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). 

Pacific White-Sided Dolphin 

Pacific white-sided dolphins are a 

pelagic species. They are found 

throughout the temperate North Pacific 

Ocean, north of the coasts of Japan and 

Baja California, Mexico (Muto et al., 

2018). They are most common between 

the latitudes of 38° North and 47° North 

(from California to Washington). The 

distribution and abundance of Pacific 

white-sided dolphins may be affected by 

large-scale oceanographic occurrences, 

such as El Nin ̃ o, and by underwater 

acoustic deterrent devices (NPS 2018a). 

Scientific studies and data are lacking 

relative to the presence or abundance of 

Pacific white-sided dolphins in or near 

Nichols Passage. Although they 

generally prefer deeper and more 

offshore waters, anecdotal reports 

suggest that Pacific white-sided 

dolphins have previously been observed 

in Nichols Passage, although they have 

not been observed in Nichols Passage or 

nearby inter-island waterways for 15 to 

20 years. When Pacific white-sided 

dolphins have been observed, sighting 

rates were highest in spring and 

decreased throughout summer and fall 

(Dahlheim et al., 2009). Most 

observations of Pacific white-sided 

dolphins occur off the outer coast or in 

inland waterways near entrances to the 

open ocean. According to Muto et al. 

(2018), aerial surveys in 1997 sighted 

one group of 164 Pacific white-sided 

dolphins in Dixon entrance to the south 

of Metlakatla. Surveys in April and May 

from 1991 to 1993 identified Pacific 

white-sided dolphins in Revillagigedo 

Channel, Behm Canal, and Clarence 

Strait (Dahlheim and Towell 1994). 

These areas are contiguous with the 

open ocean waters of Dixon Entrance. 

These observational data, combined 

with anecdotal information, indicate 

that there is a small potential for Pacific 

white-sided dolphins to occur in the 

Project area. In nearby Tongass Narrows, 

NMFS estimated that one group of 92 

Pacific white-sided dolphin may occur 

over a period of 1 year (85 FR 673), 

based on the median between 20 and 

164 Pacific-white sided dolphins (Muto 

et al., 2018). A recent monitoring report 

for Tongass Narrows reported no 

sighting of Pacific white-sided dolphins 

in May 2021 (report available at https:// 

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). 


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Dall’s Porpoise 

Dall’s porpoises are widely 

distributed across the entire North 

Pacific Ocean. They show some 

migration patterns, inshore and offshore 

and north and south, based on 

morphology and type, geography, and 

seasonality (Muto et al., 2018). They are 

common in most of the larger, deeper 

channels in Southeast Alaska and are 

rare in most narrow waterways, 

especially those that are relatively 

shallow and/or with no outlets 

(Jefferson et al., 2019). In Southeast 

Alaska, abundance varies with season. 

Jefferson et al. (2019) recently 

published a report with survey data 

spanning from 1991 to 2012 that studied 

Dall’s porpoise density and abundance 

in Southeast Alaska. They found Dall’s 

porpoise were most abundant in spring, 

observed with lower numbers in 

summer, and lowest in fall. Their 

relative rarity is supported by Jefferson 

et al. (2019) presentation of historical 

survey data showing very few sightings 

in the Ketchikan area (north of 

Metlakatla) and conclusion that Dall’s 

porpoise generally are rare in narrow 

waterways. 

No systematic studies of Dall’s 

porpoise abundance or distribution have 

occurred in Port Chester or Nichols 

Passage; however, Dall’s porpoises have 

been consistently observed in Lynn 

Canal, Stephens Passage, upper 

Chatham Strait, Frederick Sound, and 

Clarence Strait (Dahlheim et al. 2009). 

The species is generally found in waters 

in excess of 183 m (600 ft) deep, which 

do not occur in Port Chester. Despite 

generalized water depth preferences, 

Dall’s porpoises may occur in shallower 

waters. Moran et al. (2018) recently 

mapped Dall’s porpoise distributions in 

bays, shallow water, and nearshore 

areas of Prince William Sound, habitats 

not typically utilized by this species. If 

Dall’s porpoises occur in the project 

area, they will likely be present in 

March or April, given the strong 

seasonal patterns observed in nearby 

areas of Southeast Alaska (Dahlheim et 

al. 2009). Dall’s porpoises are seen once 

a month or less within Port Chester and 

Nichols Passage in groups of less than 

10 animals (L. Bethel, personal 

communication, June 11, 2020 as cited 

in the application). In nearby Tongass 

Narrows, NMFS estimated that 15 Dall’s 

porpoises per month may be present 

based on local reports of Dall’s 

porpoises typically occuring in groups 

of 10–15 animals in the area of 

Ketchikan (Freitag 2017 cited in 85 FR 

673). A recent monitoring report for 

Tongass Narrows reported no sighting of 

Dall’s porpoise in May 2021(report 

available at https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). 

Harbor Porpoise 

In the eastern North Pacific Ocean, 

the Bering Sea and Gulf of Alaska 

harbor porpoise stocks range from Point 

Barrow, along the Alaska coast, and the 

west coast of North America to Point 

Conception, California. The Southeast 

Alaska stock ranges from Cape Suckling, 

Alaska to the northern border of British 

Columbia. Within the inland waters of 

Southeast Alaska, harbor porpoises’ 

distribution is clustered with greatest 

densities observed in the Glacier Bay/ 

Icy Strait region and near Zarembo and 

Wrangell Islands and the adjacent 

waters of Sumner Strait (Dahlheim et 

al., 2015). 

There is no official stock abundance 

associated with the SARs for harbor 

porpoise. Both aerial and vessel based 

surveys have been conducted for this 

species. Aerial surveys of this stock 

were conducted in June and July 1997 

and resulted in an observed abundance 

estimate of 3,766 harbor porpoise 

(Hobbs and Waite 2010) and the surveys 

included a subset of smaller bays and 

inlets. Correction factors for observer 

perception bias and porpoise 

availability at the surface were used to 

develop an estimated corrected 

abundance of 11,146 harbor porpoise in 

the coastal and inside waters of 

Southeast Alaska (Hobbs and Waite 

2010). Vessel based spanning the 22- 

year study (1991–2012) found the 

relative abundance of harbor porpoise 

varied in the inland waters of Southeast 

Alaska. Abundance estimated in 1991– 

1993 (N = 1,076; percent CI = 910– 

1,272) was higher than the estimate 

obtained for 2006–2007 (N = 604; 95 

percent CI = 468–780) but comparable to 

the estimate for 2010–2012 (N = 975; 95 

percent CI = 857–1,109; Dahlheim et al., 

2015). These estimates assume the 

probability of detection directly on the 

trackline to be unity (g(0) = 1) because 

estimates of g(0) could not be computed 

for these surveys. Therefore, these 

abundance estimates may be biased low 

to an unknown degree. A range of 

possible g(0) values for harbor porpoise 

vessel surveys in other regions is 0.5– 

0.8 (Barlow 1988, Palka 1995), 

suggesting that as much as 50 percent of 

the porpoise can be missed, even by 

experienced observers. 

Further, other vessel based survey 

data (2010–2012) for the inland waters 

of Southeast Alaska, calculated 

abundance estimates for the 

concentrations of harbor porpoise in the 

northern and southern regions of the 

inland waters (Dahlheim et al. 2015). 

The resulting abundance estimates are 

398 harbor porpoise (CV = 0.12) in the 

northern inland waters (including Cross 

Sound, Icy Strait, Glacier Bay, Lynn 

Canal, Stephens Passage, and Chatham 

Strait) and 577 harbor porpoise (CV = 

0.14) in the southern inland waters 

(including Frederick Sound, Sumner 

Strait, Wrangell and Zarembo Islands, 

and Clarence Strait as far south as 

Ketchikan). Because these abundance 

estimates have not been corrected for 

g(0), these estimates are likely 

underestimates. 

The vessel based surveys are not 

complete coverage of harbor porpoise 

habitat and not corrected for bias and 

likely underestimate the abundance. 

Whereas, the aerial survey in 1997, 

although outdated, had better coverage 

of the range and is likely to be more of 

an accurate representation of the stock 

abundance (11,146 harbor porpoise) in 

the coastal and inside waters of 

Southeast Alaska. Although there have 

been no systematic studies or 

observations of harbor porpoises 

specific to Port Chester or Nichols 

Passage, there is potential for them to 

occur within the project area. 

Approximately one to two groups of 

harbor porpoises are observed each 

week in group sizes of up to 10 animals 

around Driest Point, located 5 km (3.1 

mi) north of the Project location (L. 

Bethel, personal communication, June 

11, 2020 as cited in the application). 

Their small overall size, lack of a visible 

blow, low dorsal fins and overall low 

profile, and short surfacing time make 

harbor porpoises difficult to spot 

(Dahlheim et al. 2015), likely reducing 

identification and reporting of this 

species, and these estimates therefore 

may be low. Harbor porpoises prefer 

shallower waters (Dahlheim et al. 2015) 

and generally are not attracted to areas 

with elevated levels of vessel activity 

and noise such as Port Chester. In 

nearby Tongass Narrrows, NMFS 

estimated that two groups of five harbor 

porpoises per month could be present 

(85 FR 673) based on local reports that 

harbor porpoises typically occur in 

groups of one to five animals and pass 

through in the area of Ketchikan 0–1 

times a month (Freitag 2017 as cited in 

85 FR 673). A recent monitoring report 

for Tongass Narrows reported no 

sighting of harbor porpoise in May 2021 

(report available at https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). 


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34210 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 

Harbor Seal 

Harbor seals range from Baja 

California north along the west coasts of 

Washington, Oregon, California, British 

Columbia, and Southeast Alaska; west 

through the Gulf of Alaska, Prince 

William Sound, and the Aleutian 

Islands; and north in the Bering Sea to 

Cape Newenham and the Pribilof 

Islands. They haul out on rocks, reefs, 

beaches, and drifting glacial ice and 

feed in marine, estuarine, and 

occasionally fresh waters. Harbor seals 

are generally non-migratory and, with 

local movements associated with such 

factors as tide, weather, season, food 

availability and reproduction. 

The Clarence Strait stock of harbor 

seals is present within the project area. 

Harbor seals are commonly sighted in 

the waters of the inside passages 

throughout Southeast Alaska. Surveys 

in 2015 estimated 429 (95% Confidence 

Interval (CI): 102–1,203) harbor seals on 

the northwest coast of Annettte Island, 

between Metlakatla and Walden Point. 

An additional 90 (95% CI: 18–292) were 

observed along the southwest coast of 

Annette Island, between Metlakatla and 

Tamgas Harbor (NOAA 2019). The 

Alaska Fisheries Science Center 

identifies three haulouts in Port Chester 

(1.5–1.8 mi from Metlakatla) and three 

additional haulouts north of Driest Point 

(3+ mi from Metlakatla) (see Figure 4– 

2 of the application). Abundance 

estimates for these haulouts are not 

available, but they are all denoted as 

having had more than 50 harbor seals at 

one point in time (NOAA 2020). 

However, local biologists report only 

small numbers (fewer than 10) of harbor 

seals are regularly observed in Port 

Chester. As many as 10 to 15 harbor 

seals may utilize Sylburn Harbor, 

located 6 km (3.7 mi) north of 

Metlakatla across Driest Point (R. Cook, 

personal communication, June 5, 2020 

as cited in the application), as a haulout 

location. In nearby Tongass Narrows, 

NMFS estimated that two groups of 

three harbor seals would be present 

every day (85 FR 673) based on based 

on local reports that harbor seals 

typically occur in groups of one to three 

animals and occur every day of the 

month in the area of Ketchikan (Freitag 

2017 as cited in 85 FR 673). A recent 

monitoring report for Tongass Narrows 

reported 28 individual sighting of 

harbor seals with 18 takes by Level B 

harassment in May 2021 (report 

available at https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). Harbor seals are known 

to be curious and may approach novel 

activity, so it is possible some may enter 

the project area during pile driving 

activities. 

Steller Sea Lion 

Steller sea lions range along the North 

Pacific Rim from northern Japan to 

California, with centers of abundance in 

the Gulf of Alaska and Aleutian Islands 

(Loughlin et al., 1984). 

Of the two Steller sea lion 

populations in Alaska, the Eastern DPS 

includes sea lions born on rookeries 

from California north through Southeast 

Alaska and the Western DPS includes 

those animals born on rookeries from 

Prince William Sound westward, with 

an eastern boundary set at 144° W 

(NMFS 2018h). Only Eastern DPS 

Steller sea lions are considered in this 

application as Western DPS Steller sea 

lions are not typically found south of 

Sumner Strait. Steller sea lions are not 

known to migrate annually, but 

individuals may widely disperse 

outside of the breeding season (late-May 

to early-July), leading to intermixing of 

stocks (Jemison et al. 2013; Allen and 

Angliss 2015). 

Steller sea lions are common in the 

inside waters of Southeast Alaska. They 

are residents of the project vicinity and 

are common year-round in the action 

area, moving their haulouts based on 

seasonal concentrations of prey from 

exposed rookeries nearer the open 

Pacific Ocean during the summer to 

more protected sites in the winter 

(Alaska Department of Fish & Game 

(ADF&G) 2018). 

Steller sea lions are common within 

the project area; however, systematic 

counts or surveys have not been 

completed in the area directly 

surrounding Metlakatla. Three haulouts 

are located within 150 km (93 mi) of the 

project area (Fritz et al. 2016a; see 

Figure 4–1 of the application); the 

nearest documented haulout is West 

Rock, about 45 km (28 mi) south of 

Metlakatla. West Rock had a count of 

703 individuals during a June 2017 

survey and 1,101 individuals during a 

June 2019 survey (Sweeney et al. 2017, 

2019). Aerial surveys occurred 

intermittently between 1994 and 2015, 

and averaged 982 adult Steller sea lions 

(Fritz et al. 2016b). Anecdotal evidence 

provided by local captains and 

biologists indicate that 3 to 4 Steller sea 

lions utilize a buoy as a haulout near the 

entrance of Port Chester, about 3.2 km 

(2 mi) from the project area (L. Bethel, 

personal communication, June 11, 2020 

2020 as cited in the application). Steller 

sea lions are not known to congregate 

near the cannery in Metlakatla. In 

nearby Tongass Narrows, NMFS 

estimated that one group of 10 Steller 

sea lions could be present each day, and 

double that rate during herring and 

salmon runs in March through May and 

July through September (85 FR 673) 

based on local reports of Steller sea 

lions typically occurring in groups of 

1–10 animals and every day of the 

month in the area of Ketchikan (Freitag 

2017 as cited in 85 FR 673). A recent 

monitoring report for Tongass Narrows 

reported 41 individual sightings of 

Steller sea lions with 9 takes by Level 

B harassment in May 2021 (report 

available at https://

www.fisheries.noaa.gov/action/ 

incidental-take-authorization-alaskadepartment-transportation-ferry-berthimprovements). Local observations in 

Metlakatla suggest that the species 

assemblages and abundance in 

Metlakatla are similar to Tongass 

Narrows. 

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. Current data indicate 

that 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) 

recommended that marine mammals be 

divided into functional hearing groups 

based on directly measured or estimated 

hearing ranges on the basis of available 

behavioral response data, audiograms 

derived using auditory evoked potential 

techniques, anatomical modeling, and 

other data. 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 3. 


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Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 34211 

TABLE 3—MARINE MAMMAL HEARING GROUPS

[NMFS, 2018] 

Hearing group Generalized hearing 

range * 

Low-frequency (LF) cetaceans (baleen whales) ..................................................................................................................... 7 Hz to 35 kHz. 

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

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

australis).

275 Hz to 160 kHz. 

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

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

* Represents the generalized hearing range for the entire group as a composite (i.e., all species within the group), where individual species’ 

hearing ranges are typically not as broad. Generalized hearing range chosen based on ∼65 dB threshold from normalized composite audiogram, 

with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation). 

The pinniped functional hearing 

group was modified from Southall et al. 

(2007) on the basis of data indicating 

that phocid species have consistently 

demonstrated an extended frequency 

range of hearing compared to otariids, 

especially in the higher frequency range 

(Hemila ̈ et al., 2006; Kastelein et al., 

2009; Reichmuth and Holt, 2013). 

For more detail concerning these 

groups and associated frequency ranges, 

please see NMFS (2018) for a review of 

available information. Eight marine 

mammal species (six cetacean and two 

pinniped (one otariid and one phocid) 

species) have the reasonable potential to 

occur during the proposed activities. 

Please refer to Table 2. Of the cetacean 

species that may be present, two are 

classified as low-frequency cetaceans 

(i.e., all mysticete species), two are 

classified as mid-frequency cetaceans 

(i.e., all delphinid species), and two are 

classified as high-frequency cetaceans 

(i.e., porpoise). 

Potential Effects of Specified Activities 

on Marine Mammals and Their Habitat 

This section includes a summary and 

discussion of the ways that components 

of the specified activity may impact 

marine mammals and their habitat. The 

Estimated Take section later in this 

document includes a quantitative 

analysis of the number of individuals 

that are expected to be taken by this 

activity. The Negligible Impact Analysis 

and Determination section considers the 

content of this section, the Estimated 

Take section, and the Proposed 

Mitigation section, to draw conclusions 

regarding the likely impacts of these 

activities on the reproductive success or 

survivorship of individuals and how 

those impacts on individuals are likely 

to impact marine mammal species or 

stocks. 

Acoustic effects on marine mammals 

during the specified activity can occur 

from vibratory and impact pile driving 

as well as during DTH of the piles. The 

effects of underwater noise from the 

AKDOT&PF’s proposed activities have 

the potential to result in Level B 

behavioral harassment of marine 

mammals in the vicinity of the action 

area. 

Description of Sound Sources 

This section contains a brief technical 

background on sound, on the 

characteristics of certain sound types, 

and on metrics used in this proposal 

inasmuch as the information is relevant 

to the specified activity and to a 

discussion of the potential effects of the 

specified activity on marine mammals 

found later in this document. For 

general information on sound and its 

interaction with the marine 

environment, please see, e.g., Au and 

Hastings (2008); Richardson et al. 

(1995); Urick (1983). 

Sound travels in waves, the basic 

components of which are frequency, 

wavelength, velocity, and amplitude. 

Frequency is the number of pressure 

waves that pass by a reference point per 

unit of time and is measured in hertz 

(Hz) or cycles per second. Wavelength is 

the distance between two peaks or 

corresponding points of a sound wave 

(length of one cycle). Higher frequency 

sounds have shorter wavelengths than 

lower frequency sounds, and typically 

attenuate (decrease) more rapidly, 

except in certain cases in shallower 

water. Amplitude is the height of the 

sound pressure wave or the ‘‘loudness’’ 

of a sound and is typically described 

using the relative unit of the decibel 

(dB). A sound pressure level (SPL) in dB 

is described as the ratio between a 

measured pressure and a reference 

pressure (for underwater sound, this is 

1 microPascal (mPa)), and is a 

logarithmic unit that accounts for large 

variations in amplitude; therefore, a 

relatively small change in dB 

corresponds to large changes in sound 

pressure. The source level (SL) 

represents the SPL referenced at a 

distance of 1 m from the source 

(referenced to 1 mPa), while the received 

level is the SPL at the listener’s position 

(referenced to 1 mPa). 

Root mean square (rms) is the 

quadratic mean sound pressure over the 

duration of an impulse. Root mean 

square is calculated by squaring all of 

the sound amplitudes, averaging the 

squares, and then taking the square root 

of the average (Urick, 1983). Root mean 

square accounts for both positive and 

negative values; squaring the pressures 

makes all values positive so that they 

may be accounted for in the summation 

of pressure levels (Hastings and Popper, 

2005). This measurement is often used 

in the context of discussing behavioral 

effects, in part because behavioral 

effects, which often result from auditory 

cues, may be better expressed through 

averaged units than by peak pressures. 

Sound exposure level (SEL; 

represented as dB re 1 mPa2-s) represents 

the total energy in a stated frequency 

band over a stated time interval or 

event, and considers both intensity and 

duration of exposure. The per-pulse SEL 

is calculated over the time window 

containing the entire pulse (i.e., 100 

percent of the acoustic energy). SEL is 

a cumulative metric; it can be 

accumulated over a single pulse, or 

calculated over periods containing 

multiple pulses. Cumulative SEL 

represents the total energy accumulated 

by a receiver over a defined time 

window or during an event. Peak sound 

pressure (also referred to as zero-to-peak 

sound pressure or 0-pk) is the maximum 

instantaneous sound pressure 

measurable in the water at a specified 

distance from the source, and is 

represented in the same units as the rms 

sound pressure. 

When underwater objects vibrate or 

activity occurs, sound-pressure waves 

are created. These waves alternately 

compress and decompress the water as 

the sound wave travels. Underwater 

sound waves radiate in a manner similar 

to ripples on the surface of a pond and 

may be either directed in a beam or 

beams or may radiate in all directions 


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34212 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 

(omnidirectional sources), as is the case 

for sound produced by the pile driving 

activity considered here. The 

compressions and decompressions 

associated with sound waves are 

detected as changes in pressure by 

aquatic life and man-made sound 

receptors such as hydrophones. 

Even in the absence of sound from the 

specified activity, the underwater 

environment is typically loud due to 

ambient sound, which is defined as 

environmental background sound levels 

lacking a single source or point 

(Richardson et al., 1995). The sound 

level of a region is defined by the total 

acoustical energy being generated by 

known and unknown sources. These 

sources may include physical (e.g., 

wind and waves, earthquakes, ice, 

atmospheric sound), biological (e.g., 

sounds produced by marine mammals, 

fish, and invertebrates), and 

anthropogenic (e.g., vessels, dredging, 

construction) sound. A number of 

sources contribute to ambient sound, 

including wind and waves, which are a 

main source of naturally occurring 

ambient sound for frequencies between 

200 Hz and 50 kilohertz (kHz) (Mitson, 

1995). In general, ambient sound levels 

tend to increase with increasing wind 

speed and wave height. Precipitation 

can become an important component of 

total sound at frequencies above 500 Hz, 

and possibly down to 100 Hz during 

quiet times. Marine mammals can 

contribute significantly to ambient 

sound levels, as can some fish and 

snapping shrimp. The frequency band 

for biological contributions is from 

approximately 12 Hz to over 100 kHz. 

Sources of ambient sound related to 

human activity include transportation 

(surface vessels), dredging and 

construction, oil and gas drilling and 

production, geophysical surveys, sonar, 

and explosions. Vessel noise typically 

dominates the total ambient sound for 

frequencies between 20 and 300 Hz. In 

general, the frequencies of 

anthropogenic sounds are below 1 kHz 

and, if higher frequency sound levels 

are created, they attenuate rapidly. 

The sum of the various natural and 

anthropogenic sound sources that 

comprise ambient sound at any given 

location and time depends not only on 

the source levels (as determined by 

current weather conditions and levels of 

biological and human activity) but also 

on the ability of sound to propagate 

through the environment. In turn, sound 

propagation is dependent on the 

spatially and temporally varying 

properties of the water column and sea 

floor, and is frequency-dependent. As a 

result of the dependence on a large 

number of varying factors, ambient 

sound levels can be expected to vary 

widely over both coarse and fine spatial 

and temporal scales. Sound levels at a 

given frequency and location can vary 

by 10–20 decibels (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. 

Sounds are often considered to fall 

into one of two general types: Pulsed 

and non-pulsed (defined in the 

following). 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). Please see 

Southall et al. (2007) for an in-depth 

discussion of these concepts. The 

distinction between these two sound 

types is not always obvious, as certain 

signals share properties of both pulsed 

and non-pulsed sounds. A signal near a 

source could be categorized as a pulse, 

but due to propagation effects as it 

moves farther from the source, the 

signal duration becomes longer (e.g., 

Greene and Richardson, 1988). 

Pulsed sound sources (e.g., airguns, 

explosions, gunshots, sonic booms, 

impact pile driving) produce signals 

that are brief (typically considered to be 

less than one second), broadband, atonal 

transients (ANSI, 1986, 2005; Harris, 

1998; NIOSH, 1998; ISO, 2003) and 

occur either as isolated events or 

repeated in some succession. Pulsed 

sounds are all characterized by a 

relatively rapid rise from ambient 

pressure to a maximal pressure value 

followed by a rapid decay period that 

may include a period of diminishing, 

oscillating maximal and minimal 

pressures, and generally have an 

increased capacity to induce physical 

injury as compared with sounds that 

lack these features. 

Non-pulsed sounds can be tonal, 

narrowband, or broadband, brief or 

prolonged, and may be either 

continuous or intermittent (ANSI, 1995; 

NIOSH, 1998). Some of these nonpulsed sounds can be transient signals 

of short duration but without the 

essential properties of pulses (e.g., rapid 

rise time). Examples of non-pulsed 

sounds include those produced by 

vessels, aircraft, machinery operations 

such as drilling or dredging, vibratory 

pile driving, and active sonar systems. 

The duration of such sounds, as 

received at a distance, can be greatly 

extended in a highly reverberant 

environment. 

The impulsive sound generated by 

impact hammers is characterized by 

rapid rise times and high peak levels. 

Vibratory hammers produce nonimpulsive, continuous noise at levels 

significantly lower than those produced 

by impact hammers. Rise time is slower, 

reducing the probability and severity of 

injury, and sound energy is distributed 

over a greater amount of time (e.g., 

Nedwell and Edwards, 2002; Carlson et 

al., 2005). DTH is believed to produce 

sound with both impulsive and 

continuous characteristics (e.g., Denes et 

al., 2016). 

Acoustic Effects on Marine Mammals 

We previously provided general 

background information on marine 

mammal hearing (see Description of 

Marine Mammals in the Area of 

Specified Activities). 

Here, we discuss the potential effects 

of sound on marine mammals. 

Anthropogenic sounds cover a broad 

range of frequencies and sound levels 

and can have a range of highly variable 

impacts on marine life, from none or 

minor to potentially severe responses, 

depending on received levels, duration 

of exposure, behavioral context, and 

various other factors. The potential 

effects of underwater sound from active 

acoustic sources can potentially result 

in one or more of the following: 

Temporary or permanent hearing 

impairment, non-auditory physical or 

physiological effects, behavioral 

disturbance, stress, and masking 

(Richardson et al., 1995; Gordon et al., 

2004; Nowacek et al., 2007; Southall et 

al., 2007; Go ̈tz et al., 2009). The degree 

of effect is intrinsically related to the 

signal characteristics, received level, 

distance from the source, and duration 

of the sound exposure. In general, 

sudden, high level sounds can cause 

hearing loss, as can longer exposures to 

lower level sounds. Temporary or 

permanent loss of hearing will occur 

almost exclusively for noise within an 

animal’s hearing range. We first describe 

specific manifestations of acoustic 

effects before providing discussion 

specific to pile driving and removal 

activities. 

Richardson et al. (1995) described 

zones of increasing intensity of effect 

that might be expected to occur, in 

relation to distance from a source and 

assuming that the signal is within an 

animal’s hearing range. First is the area 

within which the acoustic signal would 

be audible (potentially perceived) to the 

animal but not strong enough to elicit 

any overt behavioral or physiological 

response. The next zone corresponds 

with the area where the signal is audible 

to the animal and of sufficient intensity 


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to elicit behavioral or physiological 

responsiveness. Third is a zone within 

which, for signals of high intensity, the 

received level is sufficient to potentially 

cause discomfort or tissue damage to 

auditory or other systems. Overlaying 

these zones to a certain extent is the 

area within which masking (i.e., when a 

sound interferes with or masks the 

ability of an animal to detect a signal of 

interest that is above the absolute 

hearing threshold) may occur; the 

masking zone may be highly variable in 

size. 

We describe the more severe effects 

(i.e., certain non-auditory physical or 

physiological effects) only briefly as we 

do not expect that there is a reasonable 

likelihood that pile driving may result 

in such effects (see below for further 

discussion). Potential effects from 

explosive impulsive sound sources can 

range in severity from effects such as 

behavioral disturbance or tactile 

perception to physical discomfort, slight 

injury of the internal organs and the 

auditory system, or mortality (Yelverton 

et al., 1973). Non-auditory physiological 

effects or injuries that theoretically 

might occur in marine mammals 

exposed to high level underwater sound 

or as a secondary effect of extreme 

behavioral reactions (e.g., change in 

dive profile as a result of an avoidance 

reaction) caused by exposure to sound 

include neurological effects, bubble 

formation, resonance effects, and other 

types of organ or tissue damage (Cox et 

al., 2006; Southall et al., 2007; Zimmer 

and Tyack, 2007; Tal et al., 2015). The 

construction activities considered here 

do not involve the use of devices such 

as explosives or mid-frequency tactical 

sonar that are associated with these 

types of effects. 

Threshold Shift—Note that, in the 

following discussion, we refer in many 

cases to a review article concerning 

studies of noise-induced hearing loss 

conducted from 1996–2015 (i.e., 

Finneran, 2015). For study-specific 

citations, please see that work. Marine 

mammals exposed to high-intensity 

sound, or to lower-intensity sound for 

prolonged periods, can experience 

hearing threshold shift (TS), which is 

the loss of hearing sensitivity at certain 

frequency ranges (Finneran, 2015). TS 

can be permanent (permanent threshold 

shift (PTS)), in which case the loss of 

hearing sensitivity is not fully 

recoverable, or temporary (TTS), in 

which case the animal’s hearing 

threshold would recover over time 

(Southall et al., 2007). Repeated sound 

exposure that leads to TTS could cause 

PTS. In severe cases of PTS, there can 

be total or partial deafness, while in 

most cases the animal has an impaired 

ability to hear sounds in specific 

frequency ranges (Kryter, 1985). 

When PTS occurs, there is physical 

damage to the sound receptors in the ear 

(i.e., tissue damage), whereas TTS 

represents primarily tissue fatigue and 

is reversible (Southall et al., 2007). In 

addition, other investigators have 

suggested that TTS is within the normal 

bounds of physiological variability and 

tolerance and does not represent 

physical injury (e.g., Ward, 1997). 

Therefore, NMFS does not consider TTS 

to constitute auditory injury. 

Relationships between TTS and PTS 

thresholds have not been studied in 

marine mammals, and there is no PTS 

data for cetaceans, but such 

relationships are assumed to be similar 

to those in humans and other terrestrial 

mammals. PTS typically occurs at 

exposure levels at least several decibels 

above (a 40-dB threshold shift 

approximates PTS onset; e.g., Kryter et 

al., 1966; Miller, 1974) that inducing 

mild TTS (a 6-dB threshold shift 

approximates TTS onset; e.g., Southall 

et al. 2007). Based on data from 

terrestrial mammals, a precautionary 

assumption is that the PTS thresholds 

for impulse sounds (such as impact pile 

driving pulses as received close to the 

source) are at least 6 dB higher than the 

TTS threshold on a peak-pressure basis 

and PTS cumulative sound exposure 

level thresholds are 15 to 20 dB higher 

than TTS cumulative sound exposure 

level thresholds (Southall et al., 2007). 

Given the higher level of sound or 

longer exposure duration necessary to 

cause PTS as compared with TTS, it is 

considerably less likely that PTS could 

occur. 

TTS is the mildest form of hearing 

impairment that can occur during 

exposure to sound (Kryter, 1985). While 

experiencing TTS, the hearing threshold 

rises, and a sound must be at a higher 

level in order to be heard. In terrestrial 

and marine mammals, TTS can last from 

minutes or hours to days (in cases of 

strong TTS). In many cases, hearing 

sensitivity recovers rapidly after 

exposure to the sound ends. Few data 

on sound levels and durations necessary 

to elicit mild TTS have been obtained 

for marine mammals. 

Marine mammal hearing plays a 

critical role in communication with 

conspecifics, and interpretation of 

environmental cues for purposes such 

as predator avoidance and prey capture. 

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. 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 

occurs during a time 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 

time when communication is critical for 

successful mother/calf interactions 

could have more serious impacts. 

Currently, TTS data only exist for four 

species of cetaceans (bottlenose dolphin 

(Tursiops truncatus), beluga whale 

(Delphinapterus leucas), harbor 

porpoise, and Yangtze finless porpoise 

(Neophocoena asiaeorientalis)) and 

three species of pinnipeds (northern 

elephant seal, harbor seal, and 

California sea lion) exposed to a limited 

number of sound sources (i.e., mostly 

tones and octave-band noise) in 

laboratory settings (Finneran, 2015). 

TTS was not observed in trained spotted 

(Phoca largha) and ringed (Pusa 

hispida) seals exposed to impulsive 

noise at levels matching previous 

predictions of TTS onset (Reichmuth et 

al., 2016). In general, harbor seals and 

harbor porpoises have a lower TTS 

onset than other measured pinniped or 

cetacean species (Finneran, 2015). 

Additionally, the existing marine 

mammal TTS data come from a limited 

number of individuals within these 

species. There are no data available on 

noise-induced hearing loss for 

mysticetes. For summaries of data on 

TTS in marine mammals or for further 

discussion of TTS onset thresholds, 

please see Southall et al. (2007), 

Finneran and Jenkins (2012), Finneran 

(2015), and NMFS (2018). 

Behavioral Effects—Behavioral 

disturbance may include a variety of 

effects, including subtle changes in 

behavior (e.g., minor or brief avoidance 

of an area or changes in vocalizations), 

more conspicuous changes in similar 

behavioral activities, and more 

sustained and/or potentially severe 

reactions, such as displacement from or 

abandonment of high-quality habitat. 

Behavioral responses to sound are 

highly variable and context-specific and 

any reactions depend on numerous 

intrinsic and extrinsic factors (e.g., 

species, state of maturity, experience, 

current activity, reproductive state, 

auditory sensitivity, time of day), as 

well as the interplay between factors 

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

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

2007; Archer et al., 2010). Behavioral 

reactions can vary not only among 

individuals but also within an 

individual, depending on previous 

experience with a sound source, 

context, and numerous other factors 


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(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). 

Please see Appendices B–C of Southall 

et al. (2007) for a review of studies 

involving marine mammal behavioral 

responses to sound. 

Habituation can occur when an 

animal’s response to a stimulus wanes 

with repeated exposure, usually in the 

absence of unpleasant associated events 

(Wartzok et al., 2003). Animals are most 

likely to habituate to sounds that are 

predictable and unvarying. It is 

important to note that habituation is 

appropriately considered as a 

‘‘progressive reduction in response to 

stimuli that are perceived as neither 

aversive nor beneficial,’’ rather than as, 

more generally, moderation in response 

to human disturbance (Bejder et al., 

2009). The opposite process is 

sensitization, when an unpleasant 

experience leads to subsequent 

responses, often in the form of 

avoidance, at a lower level of exposure. 

As noted, behavioral state may affect the 

type of response. For example, animals 

that are resting may show greater 

behavioral change in response to 

disturbing sound levels than animals 

that are highly motivated to remain in 

an area for feeding (Richardson et al., 

1995; NRC, 2003; Wartzok et al., 2003). 

Controlled experiments with captive 

marine mammals have showed 

pronounced behavioral reactions, 

including avoidance of loud sound 

sources (Ridgway et al., 1997; Finneran 

et al., 2003). Observed responses of wild 

marine mammals to loud pulsed sound 

sources (typically airguns or acoustic 

harassment devices) have been varied 

but often consist of avoidance behavior 

or other behavioral changes suggesting 

discomfort (Morton and Symonds, 2002; 

see also Richardson et al., 1995; 

Nowacek et al., 2007). However, many 

delphinids approach low-frequency 

airgun source vessels with no apparent 

discomfort or obvious behavioral change 

(e.g., Barkaszi et al., 2012), indicating 

the importance of frequency output in 

relation to the species’ hearing 

sensitivity. 

Available studies show wide variation 

in response to underwater sound; 

therefore, it is difficult to predict 

specifically how any given sound in a 

particular instance might affect marine 

mammals perceiving the signal. If a 

marine mammal does react briefly to an 

underwater sound by changing its 

behavior or moving a small distance, the 

impacts of the change are unlikely to be 

significant to the individual, let alone 

the stock or population. However, if a 

sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on individuals and populations 

could be significant (e.g., Lusseau and 

Bejder, 2007; Weilgart, 2007; NRC, 

2005). However, there are broad 

categories of potential response, which 

we describe in greater detail here, that 

include alteration of dive behavior, 

alteration of foraging behavior, effects to 

breathing, interference with or alteration 

of vocalization, avoidance, and flight. 

Changes in dive behavior can vary 

widely and may consist of increased or 

decreased dive times and surface 

intervals as well as changes in the rates 

of ascent and descent during a dive (e.g., 

Frankel and Clark, 2000; Costa et al., 

2003; Ng and Leung, 2003; Nowacek et 

al.; 2004; Goldbogen et al., 2013a, 

2013b). Variations in dive behavior may 

reflect interruptions in biologically 

significant activities (e.g., foraging) or 

they may be of little biological 

significance. The impact of an alteration 

to dive behavior resulting from an 

acoustic exposure depends on what the 

animal is doing at the time of the 

exposure and the type and magnitude of 

the response. 

Disruption of feeding behavior can be 

difficult to correlate with anthropogenic 

sound exposure, so it is usually inferred 

by observed displacement from known 

foraging areas, the appearance of 

secondary indicators (e.g., bubble nets 

or sediment plumes), or changes in dive 

behavior. As for other types of 

behavioral response, the frequency, 

duration, and temporal pattern of signal 

presentation, as well as differences in 

species sensitivity, are likely 

contributing factors to differences in 

response in any given circumstance 

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

2004; Madsen et al., 2006; Yazvenko et 

al., 2007). A determination of whether 

foraging disruptions incur fitness 

consequences would require 

information on or estimates of the 

energetic requirements of the affected 

individuals and the relationship 

between prey availability, foraging effort 

and success, and the life history stage of 

the animal. 

Variations in respiration naturally 

vary with different behaviors and 

alterations to breathing rate as a 

function of acoustic exposure can be 

expected to co-occur with other 

behavioral reactions, such as a flight 

response or an alteration in diving. 

However, respiration rates in and of 

themselves may be representative of 

annoyance or an acute stress response. 

Various studies have shown that 

respiration rates may either be 

unaffected or could increase, depending 

on the species and signal characteristics, 

again highlighting the importance in 

understanding species differences in the 

tolerance of underwater noise when 

determining the potential for impacts 

resulting from anthropogenic sound 

exposure (e.g., Kastelein et al., 2001, 

2005, 2006; Gailey et al., 2007; Gailey et 

al., 2016). 

Marine mammals vocalize for 

different purposes and across multiple 

modes, such as whistling, echolocation 

click production, calling, and singing. 

Changes in vocalization behavior in 

response to anthropogenic noise can 

occur for any of these modes and may 

result from a need to compete with an 

increase in background noise or may 

reflect increased vigilance or a startle 

response. For example, in the presence 

of potentially masking signals, 

humpback whales and killer whales 

have been observed to increase the 

length of their songs (Miller et al., 2000; 

Fristrup et al., 2003; Foote et al., 2004), 

while right whales have been observed 

to shift the frequency content of their 

calls upward while reducing the rate of 

calling in areas of increased 

anthropogenic noise (Parks et al., 2007). 

In some cases, animals may cease sound 

production during production of 

aversive signals (Bowles et al., 1994). 

Avoidance is the displacement of an 

individual from an area or migration 

path as a result of the presence of a 

sound or other stressors, and is one of 

the most obvious manifestations of 

disturbance in marine mammals 

(Richardson et al., 1995). For example, 

gray whales are known to change 

direction—deflecting from customary 

migratory paths—in order to avoid noise 

from airgun surveys (Malme et al., 

1984). Avoidance may be short-term, 

with animals returning to the area once 

the noise has ceased (e.g., Bowles et al., 

1994; Goold, 1996; Stone et al., 2000; 

Morton and Symonds, 2002; Gailey et 

al., 2007). Longer-term displacement is 

possible, however, which may lead to 

changes in abundance or distribution 

patterns of the affected species in the 

affected region if habituation to the 

presence of the sound does not occur 

(e.g., Blackwell et al., 2004; Bejder et al., 

2006; Teilmann et al., 2006). 

A flight response is a dramatic change 

in normal movement to a directed and 

rapid movement away from the 

perceived location of a sound source. 

The flight response differs from other 

avoidance responses in the intensity of 

the response (e.g., directed movement, 

rate of travel). Relatively little 

information on flight responses of 

marine mammals to anthropogenic 

signals exist, although observations of 

flight responses to the presence of 


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predators have occurred (Connor and 

Heithaus, 1996). The result of a flight 

response could range from brief, 

temporary exertion and displacement 

from the area where the signal provokes 

flight to, in extreme cases, marine 

mammal strandings (Evans and 

England, 2001). However, it should be 

noted that response to a perceived 

predator does not necessarily invoke 

flight (Ford and Reeves, 2008), and 

whether individuals are solitary or in 

groups may influence the response. 

Behavioral disturbance can also 

impact marine mammals in more subtle 

ways. Increased vigilance may result in 

costs related to diversion of focus and 

attention (i.e., when a response consists 

of increased vigilance, it may come at 

the cost of decreased attention to other 

critical behaviors such as foraging or 

resting). These effects have generally not 

been demonstrated for marine 

mammals, but studies involving fish 

and terrestrial animals have shown that 

increased vigilance may substantially 

reduce feeding rates (e.g., Beauchamp 

and Livoreil, 1997; Fritz et al., 2002; 

Purser and Radford, 2011). In addition, 

chronic disturbance can cause 

population declines through reduction 

of fitness (e.g., decline in body 

condition) and subsequent reduction in 

reproductive success, survival, or both 

(e.g., Harrington and Veitch, 1992; Daan 

et al., 1996; Bradshaw et al., 1998). 

However, Ridgway et al. (2006) reported 

that increased vigilance in bottlenose 

dolphins exposed to sound over a fiveday period did not cause any sleep 

deprivation or stress effects. 

Many animals perform vital functions, 

such as feeding, resting, traveling, and 

socializing, on a diel cycle (24-hour 

cycle). Disruption of such functions 

resulting from reactions to stressors 

such as sound exposure are more likely 

to be significant if they last more than 

one diel cycle or recur on subsequent 

days (Southall et al., 2007). 

Consequently, a behavioral response 

lasting less than one day and not 

recurring on subsequent days is not 

considered particularly severe unless it 

could directly affect reproduction or 

survival (Southall et al., 2007). Note that 

there is a difference between multi-day 

substantive behavioral reactions and 

multi-day anthropogenic activities. For 

example, just because an activity lasts 

for multiple days does not necessarily 

mean that individual animals are either 

exposed to activity-related stressors for 

multiple days or, further, exposed in a 

manner resulting in sustained multi-day 

substantive behavioral responses. 

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; Krausman et 

al., 2004; Lankford et al., 2005). Stress 

responses due to exposure to 

anthropogenic sounds or other stressors 

and their effects on marine mammals 

have also been reviewed (Fair and 

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

and, more rarely, studied in wild 

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

For example, Rolland et al. (2012) found 

that noise reduction from reduced ship 

traffic in the Bay of Fundy was 

associated with decreased stress in 

North Atlantic right whales. These and 

other studies lead to a reasonable 

expectation that some marine mammals 

will experience physiological stress 

responses upon exposure to acoustic 

stressors and that it is possible that 

some of these would be classified as 

‘‘distress.’’ In addition, any animal 

experiencing TTS would likely also 

experience stress responses (NRC, 

2003). 

Auditory 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; 

Erbe et al., 2016). 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., 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-to-noise ratio, temporal 

variability, direction), in relation to each 

other and to an animal’s hearing 

abilities (e.g., sensitivity, frequency 

range, critical ratios, frequency 

discrimination, directional 

discrimination, age or TTS hearing loss), 

and existing ambient noise and 

propagation conditions. 

When the coincident (masking) sound 

is man-made, it may be considered 

harassment when disrupting or altering 

critical behaviors. Further, under certain 

circumstances, marine mammals 

experiencing significant masking could 

also be impaired from maximizing their 

performance fitness in survival and 

reproduction. However, it is important 

to distinguish TTS and PTS, which 

persist after the sound exposure, from 

masking, which occurs during the 

sound exposure. Because masking 

(without resulting in TS) is not 

associated with abnormal physiological 

function, it is not considered a 

physiological effect, but rather a 

potential behavioral effect. 

The frequency range of the potentially 

masking sound is important in 

determining any potential behavioral 

impacts. For example, low-frequency 

signals may have less effect on highfrequency echolocation sounds 

produced by odontocetes but are more 

likely to affect detection of mysticete 


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communication calls and other 

potentially important natural sounds 

such as those produced by surf and 

some prey species. The masking of 

communication signals by 

anthropogenic noise may be considered 

as a reduction in the communication 

space of animals (e.g., Clark et al., 2009) 

and may result in energetic or other 

costs as animals change their 

vocalization behavior (e.g., Miller et al., 

2000; Foote et al., 2004; Parks et al., 

2007; Di Iorio and Clark, 2009; Holt et 

al., 2009). Masking can be reduced in 

situations where the signal and noise 

come from different directions 

(Richardson et al., 1995), through 

amplitude modulation of the signal, or 

through other compensatory behaviors 

(Houser and Moore, 2014). Masking can 

be tested directly in captive species 

(e.g., Erbe, 2008), but in wild 

populations it must be either modeled 

or inferred from evidence of masking 

compensation. There are few studies 

addressing real-world masking sounds 

likely to be experienced by marine 

mammals in the wild (e.g., Branstetter et 

al., 2013). 

Masking affects both senders and 

receivers of acoustic signals and can 

potentially have long-term chronic 

effects on marine mammals at the 

population level as well as at the 

individual level. Low-frequency 

ambient sound levels have increased by 

as much as 20 dB (more than three times 

in terms of SPL) in the world’s ocean 

from pre-industrial periods, with most 

of the increase from distant commercial 

shipping (Hildebrand, 2009). All 

anthropogenic sound sources, but 

especially chronic and lower-frequency 

signals (e.g., from vessel traffic), 

contribute to elevated ambient sound 

levels, thus intensifying masking. 

Potential Effects of the AKDOT&PF’s 

Activity—As described previously, the 

AKDOT&PF proposes to conduct pile 

driving, including impact and vibratory 

driving (inclusive of DTH). The effects 

of pile driving on marine mammals are 

dependent on several factors, including 

the size, type, and depth of the animal; 

the depth, intensity, and duration of the 

pile driving sound; the depth of the 

water column; the substrate of the 

habitat; the standoff distance between 

the pile and the animal; and the sound 

propagation properties of the 

environment. With both types, it is 

likely that the pile driving could result 

in temporary, short-term changes in an 

animal’s typical behavioral patterns 

and/or avoidance of the affected area. 

These behavioral changes may include 

(Richardson et al., 1995): 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; 

and/or flight responses. 

The biological significance of many of 

these behavioral disturbances is difficult 

to predict, even if the detected 

disturbances appear minor, and the 

consequences of behavioral 

modification could be expected to be 

biologically significant if the change 

affects growth, survival, or 

reproduction. However, significant 

behavioral modifications that could lead 

to effects on growth, survival, or 

reproduction, such as drastic changes in 

diving/surfacing patterns or significant 

habitat abandonment are extremely 

unlikely to result from this activity or in 

this area (i.e., shallow waters in 

modified industrial areas). 

Whether impact or vibratory driving, 

sound sources would be active for 

relatively short durations, with little 

potential for masking. Also, the 

frequencies output by pile driving 

activity are lower than those used by 

most species expected to be regularly 

present for communication or 

echolocation. We expect insignificant 

impacts from masking, and any masking 

event that could possibly rise to Level 

B harassment under the MMPA would 

occur concurrently within the zones of 

behavioral harassment already 

estimated for vibratory and impact pile 

driving, and which have already been 

taken into account in the exposure 

analysis. 

Anticipated Effects on Marine Mammal 

Habitat 

The proposed activities would not 

result in permanent impacts to habitats 

used directly by marine mammals. The 

project would occur within the same 

footprint as existing marine 

infrastructure. The nearshore and 

intertidal habitat where the project 

would occur is an area of relatively high 

marine vessel traffic. Most marine 

mammals do not generally use the area 

within the footprint of the project area. 

The proposed activities may have 

potential short-term impacts to food 

sources such as forage fish. The 

proposed activities could also affect 

acoustic habitat (see masking discussion 

above), but meaningful impacts are 

unlikely. There are no known foraging 

hotspots, or other ocean bottom 

structures of significant biological 

importance to marine mammals present 

in the marine waters in the vicinity of 

the project area. Therefore, the main 

impact issue associated with the 

proposed activity would be temporarily 

elevated sound levels and the associated 

direct effects on marine mammals, as 

discussed previously. The most likely 

impact to marine mammal habitat 

occurs from pile driving effects on likely 

marine mammal prey (i.e., fish) near 

where the piles are installed. Impacts to 

the immediate substrate during 

installation and removal of piles are 

anticipated, but these would be limited 

to minor, temporary suspension of 

sediments, which could impact water 

quality and visibility for a short amount 

of time, but which would not be 

expected to have any effects on 

individual marine mammals or the prey 

for marine mammals. Impacts to 

substrate are therefore not discussed 

further. 

Effects to Prey—Sound may affect 

marine mammals through impacts on 

the abundance, behavior, or distribution 

of prey species (e.g., crustaceans, 

cephalopods, fish, zooplankton). Marine 

mammal prey varies by species, season, 

and location and, for some, is not well 

documented. 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 et al., 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. 


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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., Pena et al., 2013; Wardle 

et al., 2001; Jorgenson and Gyselman, 

2009; Cott et al., 2012). More 

commonly, though, the impacts of noise 

on fish are temporary. 

Exposure to loud sounds with 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. 

In general, impacts to marine mammal 

prey species are expected to be minor 

and temporary due to the expected short 

daily duration of individual pile driving 

events and the relatively small areas 

being affected. 

The following essential fish habitat 

(EFH) species may occur in the project 

area during at least one phase of their 

lifestage: Chum Salmon (Oncorhynchus 

keta), Pink Salmon (O. gorbuscha), Coho 

Salmon (O. kisutch), Sockeye Salmon 

(O. nerka), and Chinook Salmon (O. 

tshawytscha). Three creeks flowing into 

Port Chester are known to contain 

salmonids: Hemlock Creek, Trout Lake 

Creek, and Melanson Lake outflow 

(Giefer and Blossom 2020); however, 

adverse effects on EFH in this area are 

not expected. 

The area impacted by the project is 

relatively small compared to the 

available habitat and does not include 

habitat of particular importance relative 

to available habitat overall. 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. As described in the 

preceding, the potential for the 

AKDOT&PF’s construction to affect the 

availability of prey to marine mammals 

or to meaningfully impact the quality of 

physical or acoustic habitat is 

considered to be insignificant. Effects to 

habitat will not be discussed further in 

this document. 

Estimated Take 

This section provides an estimate of 

the number of incidental takes proposed 

for authorization through this IHA, 

which will inform both NMFS’ 

consideration of ‘‘small numbers’’ and 

the negligible impact determination. 

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). 

Take of marine mammals incidental 

to the AKDOT&PF’s pile driving and 

removal activities (as well as during 

DTH) could occur as a result of Level B 

harassment only. Below we describe 

how the potential take is estimated. As 

described previously, no mortality is 

anticipated or proposed to be authorized 

for this activity. Below we describe how 

the take is estimated. 

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) and the number of days of 

activities. We note that while these 

basic factors can contribute to a basic 

calculation to provide an initial 

prediction of 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 estimate. 

Acoustic Thresholds 

Using the best available science, 

NMFS has developed 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 (e.g., 

frequency, predictability, duty cycle), 

the environment (e.g., bathymetry), and 

the receiving animals (hearing, 

motivation, experience, demography, 

behavioral context) and can be difficult 

to predict (Southall et al., 2007, Ellison 

et al., 2012). Based on what the 

available science indicates and the 

practical need to use a threshold based 

on a factor that is both predictable and 

measurable for most activities, NMFS 

uses a generalized acoustic threshold 

based on received level to estimate the 

onset of behavioral harassment. NMFS 

predicts that marine mammals are likely 

to be behaviorally harassed in a manner 

we consider Level B harassment when 

exposed to underwater anthropogenic 

noise above received levels of 120 dB re 

1 mPa (rms) for continuous (e.g., 

vibratory pile driving and DTH) and 

above 160 dB re 1 mPa (rms) for 

impulsive sources (e.g., impact pile 

driving). The AKDOT&PF’s proposed 

activity includes the use of continuous 

(vibratory pile driving, DTH) and 

impulsive (impact pile driving) sources, 

and therefore the 120 and 160 dB re 1 

mPa (rms) 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. The technical 

guidance identifies the received levels, 

or thresholds, above which individual 

marine mammals are predicted to 

experience changes in their hearing 

sensitivity for all underwater 

anthropogenic sound sources, and 

reflects the best available science on the 


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potential for noise to affect auditory 

sensitivity by: 

D Dividing sound sources into two 

groups (i.e., impulsive and nonimpulsive) based on their potential to 

affect hearing sensitivity; 

D Choosing metrics that best address 

the impacts of noise on hearing 

sensitivity, i.e., sound pressure level 

(peak SPL) and sound exposure level 

(SEL) (also accounts for duration of 

exposure); and 

D Dividing marine mammals into 

hearing groups and developing auditory 

weighting functions based on the 

science supporting that not all marine 

mammals hear and use sound in the 

same manner. 

These thresholds were developed by 

compiling and synthesizing the best 

available science, and are provided in 

Table 4 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. 

DTH pile installation includes drilling 

(non-impulsive sound) and hammering 

(impulsive sound) to penetrate rocky 

substrates (Denes et al. 2016; Denes et 

al. 2019; Reyff and Heyvaert 2019). DTH 

pile installation was initially thought be 

a primarily non-impulsive noise source. 

However, Denes et al. (2019) concluded 

from a study conducted in Virginia, 

nearby the location for this project, that 

DTH should be characterized as 

impulsive based on Southall et al. 

(2007), who stated that signals with a >3 

dB difference in sound pressure level in 

a 0.035-second window compared to a 

1-second window can be considered 

impulsive. Therefore, DTH pile 

installation is treated as both an 

impulsive and non-impulsive noise 

source. In order to evaluate Level A 

harassment, DTH pile installation 

activities are evaluated according to the 

impulsive criteria and using 160 dB 

rms. Level B harassment isopleths are 

determined by applying non-impulsive 

criteria and using the 120 dB rms 

threshold which is also used for 

vibratory driving. This approach 

ensures that the largest ranges to effect 

for both Level A and Level B harassment 

are accounted for in the take estimation 

process. 

TABLE 4—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT

[Auditory injury] 

Hearing group 

PTS onset acoustic thresholds *

(received level) 

Impulsive Non-impulsive 

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

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

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

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

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

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

also be considered. 

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

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

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

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

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

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

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

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

Ensonified Area 

Here, we describe operational and 

environmental parameters of the activity 

that will feed into identifying the area 

ensonified above the acoustic 

thresholds, which include source levels 

and transmission loss coefficient. 

Sound Propagation 

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: 

B = transmission loss coefficient (assumed to 

be 15) 

R1 = the distance of the modeled SPL from 

the driven pile, and 

R2 = the distance from the driven pile of the 

initial measurement. 

This formula neglects loss due to 

scattering and absorption, which is 

assumed to be zero here. The degree to 

which underwater sound propagates 

away from a sound source is dependent 

on a variety of factors, most notably the 

water bathymetry and presence or 

absence of reflective or absorptive 

conditions including in-water structures 

and sediments. Spherical spreading 

occurs in a perfectly unobstructed (freefield) environment not limited by depth 

or water surface, resulting in a 6 dB 

reduction in sound level for each 

doubling of distance from the source 

(20*log(range)). Cylindrical spreading 

occurs in an environment in which 

sound propagation is bounded by the 

water surface and sea bottom, resulting 

in a reduction of 3 dB in sound level for 

each doubling of distance from the 

source (10*log(range)). As is common 

practice in coastal waters, here we 

assume practical spreading loss (4.5 dB 

reduction in sound level for each 

doubling of distance). Practical 

spreading is a compromise that is often 

used under conditions where water 

depth increases as the receiver moves 

away from the shoreline, resulting in an 

expected propagation environment that 

would lie between spherical and 

cylindrical spreading loss conditions. 

Practical spreading was used to 

determine sound propagation for this 

project. 

Sound Source Levels 

The intensity of pile driving sounds is 

greatly influenced by factors such as the 

type of piles, hammers, and the physical 

environment in which the activity takes 

place. There are source level 


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measurements available for certain pile 

types and sizes from the similar 

environments recorded from underwater 

pile driving projects in Alaska that were 

evaluated and used as proxy sound 

source levels to determine reasonable 

sound source levels likely result from 

the AKDOT&PF’s pile driving and 

removal activities (Table 5). Many 

source levels used were more 

conservative as the values were from 

larger pile sizes. 

TABLE 5—PROPOSED SOUND SOURCE LEVELS

Method and pile type SSL at 10 meters Literature Source Federal Register sources a

Continuous (Vibratory Pile Driving and DTH) dB rms 

16-in Steel Piles ............................................. 161 Navy 2012, 2015 ........................................... A, B, C, H. 

24-in Steel Piles ............................................. 161 Navy 2012, 2015 ........................................... C, D, E, H, I. 

24-in DTH b .................................................... 166 Denes et al. 2016 (Table 72) b ...................... B, C, F, G. 

8-in DTH c ...................................................... 166 NMFSc

Impulsive (Impact Pile Driving and DTH) dB rms dB SEL dB Peak ................................................................... ...............................

24-in Steel Piles ............................................. 193 181 210 Navy 2015 ...................................................... D, H, I. 

24-in DTH b .................................................... ........................ 154 ........................ Denes et al. 2016 b ........................................

8-in DTH c ...................................................... ........................ 144 170 Reyff 2020. ....................................................

aFederal Register (FR) sources: 

A: 84 FR 24490, City of Juneau Waterfront Improvement Project, Juneau, Alaska. 

B: 85 FR 4278, Statter Harbor Improvement Project, Auke Bay, Alaska. 

C: 85 FR 673, Tongass Narrows Ferry Berth Improvements, Ketchikan, Alaska. 

D: 85 FR 19294, Port of Alaska’s Petroleum and Cement Terminal, Anchorage, Alaska. 

E: 84 FR 56767, Auke Bay Ferry Terminal Modifications and Improvements Project, Juneau, Alaska. 

F: 85 FR 18196, Gastineau Channel Historical Society Sentinel Island Moorage Float Project, Juneau, Alaska. 

G: 85 FR 12523, Ward Cove Cruise Ship Dock Project, Juneau, Alaska. 

H: 83 FR 29749, City Dock and Ferry Terminal, Tenakee Springs, Alaska. 

I: 82 FR 48987, Sand Point City Dock Replacement Project, Sand Point, Alaska. 

b DTH pile installation is treated as a continuous sound for Level B calculations and impulsive for Level A calculations. 

cTension anchor installation (8-in DTH) is currently treated as DTH pile installation. 

Notes: DTH = down-the-hole pile installation; SSL = sound source = level; dB = decibel; rms = root mean square; SEL = sound ure level.

Level A Harassment 

In conjunction with the NMFS 

Technical Guidance (2018), in 

recognition of the fact that ensonified 

area/volume could be more technically 

challenging to predict because of the 

duration component in the new 

thresholds, we developed a User 

Spreadsheet that includes tools to help 

predict a simple isopleth that can be 

used in conjunction with marine 

mammal density or occurrence to help 

predict takes. We note that because of 

some of the assumptions included in the 

methods used for these tools, we 

anticipate that isopleths produced are 

typically going to be overestimates of 

some degree, which may result in some 

degree of overestimate of Level A 

harassment take. However, these tools 

offer the best way to predict appropriate 

isopleths when more sophisticated 3D 

modeling methods are not available, and 

NMFS continues to develop ways to 

quantitatively refine these tools, and 

will qualitatively address the output 

where appropriate. For stationary 

sources (such as from impact and 

vibratory pile driving and DTH), NMFS 

User Spreadsheet (2020) predicts the 

closest distance at which, if a marine 

mammal remained at that distance the 

whole duration of the activity, it would 

not incur PTS. Inputs used in the User 

Spreadsheet (Tables 6 and 7), and the 

resulting isopleths are reported below 

(Table 8). 

TABLE 6—NMFS TECHNICAL GUIDANCE (2020) USER SPREADSHEET INPUT TO CALCULATE PTS ISOPLETHS FOR

VIBRATORY PILE DRIVING

User Spreadsheet Input—Vibratory pile driving spreadsheet tab A.1 vibratory pile driving used 

16-in piles 

(removal) 

24-in 

piles temporary 

(install/removal) 

24-in plumb/batter 

piles permanent 

(install) 

Source Level (RMS SPL) .......................................................................................... 161 161 161 

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

Number of piles within 24-hr period .......................................................................... 4 4 4 

Duration to drive a single pile (min) .......................................................................... 30 30 30 

Propagation (xLogR) .................................................................................................. 15 15 15 

Distance of source level measurement (meters) + .................................................... 10 10 10 

TABLE 7—NMFS TECHNICAL GUIDANCE (2020) USER SPREADSHEET INPUT TO CALCULATE PTS ISOPLETHS FOR IMPACT

PILE DRIVING

User spreadsheet input—impact pile driving spreadsheet Tab E.1 impact pile driving used 

24-in piles 

(permanent) 

8-in pile 

(DTH) 

8-in pile 

(DTH) 

8-in pile 

(DTH) 

24-in pile 

(DTH) 

24-in pile 

(DTH) 

24-in pile 

(DTH) 

Source Level (Single Strike/shot SEL) ......... 181 144 144 144 154 154 154 

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

Number of strikes per pile ............................. 20 54,000 108,000 162,000 54,000 81,000 162,000 


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TABLE 7—NMFS TECHNICAL GUIDANCE (2020) USER SPREADSHEET INPUT TO CALCULATE PTS ISOPLETHS FOR IMPACT

PILE DRIVING—Continued 

User spreadsheet input—impact pile driving spreadsheet Tab E.1 impact pile driving used 

24-in piles 

(permanent) 

8-in pile 

(DTH) 

8-in pile 

(DTH) 

8-in pile 

(DTH) 

24-in pile 

(DTH) 

24-in pile 

(DTH) 

24-in pile 

(DTH) 

Minutes per pile ............................................. ........................ 60 120 180 60 90 180 

Number of piles per day ............................... 3 1 1 1 1 1 1 

Propagation (xLogR) ..................................... 15 15 15 15 15 15 15 

Distance of source level measurement (meters) ∂ ........................................................ 10 10 10 10 10 10 10 

TABLE 8—NMFS TECHNICAL GUIDANCE (2020) USER SPREADSHEET OUTPUTS TO CALCULATE LEVEL A HARASSMENT

PTS ISOPLETHS

User spreadsheet output PTS isopleths (meters) 

Activity Sound source level at 

10 m 

Level A harassment 

Low-frequency 

cetaceans 

Mid-frequency 

cetaceans 

High-frequency 

cetaceans Phocid Otariid 

Vibratory Pile Driving/Removal 

16-in steel pile removal ............................................. 161 SPL ..................... 10.8 1.0 16.0 6.6 0.5 

24-in steel pile temporary installation and removal .. 161 SPL ..................... 10.8 1.0 16.0 6.6 0.5 

24-in steel pile permanent ........................................ 161 SPL ..................... 10.8 1.0 16.0 6.6 0.5 

Impact Pile Driving 

24-in steel permanent installation (3 piles a day) ..... 181 SEL/193 SPL ...... 112.6 4.0 134.1 60.3 4.4 

24-in steel permanent installation (2 piles a day) ..... 181 SEL/193 SPL ...... 85.9 3.1 102.3 46.0 3.3 

24-in steel permanent installation (1 piles a day) ..... 181 SEL/193 SPL ...... 54.1 1.9 64.5 29.0 2.1 

DTH 

8-in steel (60 min) ..................................................... 144 SEL/166 SPL ...... 35.8 1.3 42.7 19.2 1.4 

8-in steel (120 min) ................................................... 144 SEL/166 SPL ...... 56.9 2.0 67.8 30.4 2.2 

8-in steel (180 min) ................................................... 144 SEL/166 SPL ...... 74.5 2.7 88.8 39.9 2.9 

24-in steel (60 min) ................................................... 154 SEL/166 SPL ...... 166.3 5.9 198.1 89.0 6.5 

24-in steel (90 min) ................................................... 154 SEL/166 SPL ...... 218.0 7.8 259.6 116.6 8.5 

24-in steel (180 min) ................................................. 154 SEL/166 SPL ...... 346.0 12.3 412.1 185.2 13.5 

Level B Harassment 

Utilizing the practical spreading loss 

model, the AKDOT&PF determined 

underwater noise will fall below the 

behavioral effects threshold of 120 dB 

rms for marine mammals at the 

distances shown in Table 9 for vibratory 

pile driving/removal, and DTH. With 

these radial distances, the largest Level 

B harassment zone calculated was for 

DTH at 11,659 m. For calculating the 

Level B harassment zone for impact 

driving, the practical spreading loss 

model was used with a behavioral 

threshold of 160 dB rms. The maximum 

radial distance of the Level B 

harassment zone for impact piling 

equaled 1,585 m for 24-in piles. Table 

9 below provides all Level B harassment 

radial distances (m) during the 

AKDOT&PF’s proposed activities. 

TABLE 9—RADIAL DISTANCES (METERS) TO RELEVANT BEHAVIORAL ISOPLETHS

Activity Received level at 10 meters 

(m) 

Level B harassment zone 

(m) * 

Vibratory Pile Driving/Removal and DTH 

16-in steel piles ................................................................ 161 SPL ............................. 5,415 (calculated 5,412). 

24-in steel piles ................................................................ 161 SPL ............................. 5,415 (calculated 5,412). 

8-in and 24-in DTH ........................................................... 166 SPL ............................. 11,660 (calculated 11,659). 

Impact Pile Driving 

24-in steel piles ................................................................ 181 SEL/193 SPL .............. 1,585. 

* Numbers rounded up to nearest 5 meters. These specific rounded distances are for monitoring purposes rather than take estimation. 

Marine Mammal Occurrence and Take 

Calculation and Estimation 

In this section we provide the 

information about the presence, density, 

or group dynamics of marine mammals 

that will inform the take calculations. 

Potential exposures to impact pile 

driving, vibratory pile driving/removal 

and DTH noises for each acoustic 

threshold were estimated using group 

size estimates and local observational 

data. As shown above, distances to 

Level A harassment thresholds for 

project activities are relatively small and 

mitigation (i.e., shutdown zones) is 

expected to avoid Level A harassment 

from these activities. Accordingly, take 


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by Level B harassment only will be 

considered for this action. Take by Level 

B harassment are calculated differently 

for some species based on monthly or 

daily sightings data and average group 

sizes within the action area using the 

best available data. 

Minke Whales 

There are no density estimates of 

minke whales available in the project 

area. These whales are usually sighted 

individually or in small groups of two 

or three, but there are reports of loose 

aggregations of hundreds of animals 

(NMFS 2018). Dedicated surveys for 

cetaceans in Southeast Alaska found 

that minke whales were scattered 

throughout inland waters from Glacier 

Bay and Icy Strait to Clarence Strait 

(Dahlheim et al. 2009). All sightings 

were of single minke whales, except for 

a single sighting of multiple minke 

whales. Anecdotal observations suggest 

that minke whales do not enter Port 

Chester, and may be more rare in the 

project area (L. Bethel, personal 

communication, June 11, 2020 as cited 

in the application). Based on the 

potential for one group of a group size 

of three whales entering the Level B 

harassment zone during the project, 

similar to what is observed in Tongass 

Narrows, AKDOT&PF requested, and 

NMFS proposes to authorize, take of 

three minke whales over the 4-month 

project period by Level B harassment. 

No take by Level A harassment is 

proposed for authorization or 

anticipated to occur due to their rarer 

occurrence in the project area. In 

addition, the shutdown zones are larger 

than all the calculated Level A 

harassment isopleths for all pile 

driving/removal and DTH activities for 

cetaceans. 

Humpback Whales 

There are no density estimates of 

humpback whales available in the 

project area. Use of Nichols Passage and 

Port Chester by humpback whales is 

common but intermittent and 

dependent on the presence of prey fish. 

No systematic studies have documented 

humpback whale abundance near 

Metlakatla. Anecdotal information from 

Metlakatla and Ketchikan suggest that 

humpback whales’ utilization of the 

area is intermittent year-round and local 

mariners estimate that one to two 

humpback whales may be present in the 

Port Chester area on a daily basis during 

summer months (L. Bethel, personal 

communication, June 11, 2020 2020 as 

cited in the application). This is 

consistent with reports from Ketchikan, 

which suggest that humpback whales 

occur alone or in groups of two or three 

individuals and abundance is highest in 

August and September (84 FR 34134). 

However, anecdotal reports suggest that 

humpback whale abundance is higher 

and occurrence is more regular in 

Metlakatla. Therefore, AKDOT&PF 

requested and NMFS proposes that two 

groups of two whales, up to four 

individuals per day, may be taken by 

Level B harassment for a total of 104 

humpback whales (4 whales per day * 

26 days = 104 humpback whales). 

Under the MMPA, humpback whales 

are considered a single stock (Central 

North Pacific); however, we have 

divided them here to account for DPSs 

listed under the ESA. Using the stock 

assessment from Muto et al. 2020 for the 

Central North Pacific stock (10,103 

whales) and calculations in Wade et al. 

2016; 9,487 whales are expected to be 

from the Hawaii DPS and 606 from the 

Mexico DPS. Therefore, for purposes of 

consultation under the ESA, we 

anticipate that 7 whales of the total 

takes would be individuals from the 

Mexico DPS (104 × 0.061 = 6.3 rounded 

to 7). No take by Level A harassment is 

proposed for authorization or 

anticipated to occur due to their large 

size and ability to be visibly detected in 

the project area if an animal should 

approach the Level A harassment zone 

as well as the size of the Level A 

harassment zones, which are expected 

to be manageable for the PSOs. The 

calculated Level A isopleths for lowfrequency cetaceans are 113 m or less 

with the exception of DTH of limited 

duration of 24-in piles where they range 

from 166.3–346.0 m. The shutdown 

zones (Table 11) are larger for all 

calculated Level A harassment isopleths 

during all pile driving activities 

(vibratory, impact and DTH) for all 

cetaceans. 

Killer Whales 

There are no density estimates of 

killer whales available in the project 

area. Three distinct eco-types occur in 

Southeast Alaska (resident, transient 

and offshore whales; Ford et al., 1994; 

Dahlheim et al., 1997, 2008). Dahlheim 

et al. (2009) observed transient killer 

whales within Lynn Canal, Icy Strait, 

Stephens Passage, Frederick Sound, and 

upper Chatham Strait. As determined 

during a line-transect survey by 

Dalheim et al. (2008), the greatest 

number of transient killer whale 

observed in Southeast Alaska occurred 

in 1993 with 32 animals seen over 2 

months for an average of 16 sightings 

per month. Resident pods were also 

observed in Icy Strait, Lynn Canal, 

Stephens Passage, Frederick Sound and 

upper Chatham Straight (Dalheim et al. 

2008). Transient killer whales are often 

found in long-term stable social units 

(pods) of 1 to 16 whales. Average pod 

sizes in Southeast Alaska were 6 in 

spring, 5 in summer, and 4 in fall. Pod 

sizes of transient whales are generally 

smaller than those of resident social 

groups. Resident killer whales occur in 

pods ranging from 7 to 70 whales that 

are seen in association with one another 

more than 50 percent of the time 

(Dahlheim et al. 2009; NMFS 2016b). In 

Southeast Alaska, resident killer whale 

mean pod size was approximately 21.5 

in spring, 32.3 in summer, and 19.3 in 

fall (Dahlheim et al. 2009). Killer whales 

are observed occasionally during 

summer throughout Nichols Passage, 

but their presence in Port Chester is 

unlikely. Anecdotal local information 

suggests that killer whales are rarely 

seen within the Port Chester area, but 

may be present more frequently in 

Nichols Passage and other areas around 

Gravina Island (L. Bethel, personal 

communication, June 11, 2020 2020 as 

cited in the application). To be 

conservative AKDOT&PF requested one 

killer whale pod of up to 15 individuals 

once during the project could be taken 

by Level B harassment based on a pod 

of 12 killer whales that may be present 

each month similar to Tongass Narrows 

near Ketchikan. Additionally, a recent 

monitoring report for Tongass Narrows 

reported 10 individuals sighted and 10 

Level B harassment takes of killer 

whales during May 2021. No take by 

Level A harassment is proposed for 

authorization or anticipated to occur to 

the ability to visibly detect these large 

whales and the small size of the Level 

A harassment zones. In addition, the 

shutdown zones are larger than all the 

calculated Level A harassment isopleths 

for all pile driving/removal and DTH 

activities for cetaceans. 

Pacific White-Sided Dolphin 

There are no density estimates of 

Pacific white-sided dolphins available 

in the project area. Most observations of 

Pacific white-sided dolphins occur off 

the outer coast or in inland waterways 

near entrances to the open ocean. 

Pacific white-sided dolphins have been 

observed in Alaska waters in groups 

ranging from 20 to 164 animals, with the 

sighting of 164 animals occurring in 

Southeast Alaska near Dixon Entrance 

to the south of Metlakatla (Muto et al., 

2018). In nearby Tongass Narrows, 

NMFS estimated that one group of 92 

Pacific white-sided dolphin (median 

between 20 and 164) may occur over a 

period of 1 year (85 FR 673). There are 

no records of this species occurring in 

Port Chester, and it is uncommon for 

individuals to occur in the project area. 

Therefore, the AKDOT&PF requested 


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and NMFS proposes one large group of 

92 dolphins may be taken by Level B 

harassment during the project. No take 

by Level A harassment is proposed or 

anticipated as the Level A harassment 

isopleths are so small. 

Dall’s Porpoise 

There are no density estimates of 

Dall’s porpoise available in the project 

area. Little information is available on 

the abundance of Dall’s porpoise in the 

inland waters of Southeast Alaska. 

Dall’s porpoise are most abundant in 

spring, observed with lower numbers in 

the summer, and lowest numbers in fall. 

Jefferson et al., 2019 presents 

abundance estimates for Dall’s porpoise 

in these waters and found the 

abundance in summer (N = 2,680, CV = 

19.6 percent), and lowest in fall (N = 

1,637, CV = 23.3 percent). No systematic 

studies of Dall’s porpoise abundance or 

distribution have occurred in Port 

Chester or Nichols Passage; however, 

Dall’s porpoises have been consistently 

observed in Lynn Canal, Stephens 

Passage, upper Chatham Strait, 

Frederick Sound, and Clarence Strait 

(Dahlheim et al. 2009). The species is 

generally found in waters in excess of 

600 ft (183 m) deep, which do not occur 

in Port Chester. If Dall’s porpoises occur 

in the project area, they will likely be 

present in March or April, given the 

strong seasonal patterns observed in 

nearby areas of Southeast Alaska 

(Dahlheim et al. 2009). Dall’s porpoises 

are seen once a month or less within 

Port Chester and Nichols Passage in 

groups of less than 10 animals (L. 

Bethel, personal communication, June 

11, 2020 as cited in the application). 

Dall’s porpoises are not expected to 

occur in Port Chester because the 

shallow water habitat of the bay is 

atypical of areas where Dall’s porpoises 

usually occur. Therefore, AKDOT&PF 

requests and NMFS proposes one group 

of Dall’s porpoise (15 individuals) per 

month, similar to what was estimated in 

nearby Tongass Narrows, may be taken 

by Level B harassment for a total of 30 

Dall’s porpoises during the 26 days of 

in-water construction (2 months * 15 

porpoises per month = 30). No take by 

Level A harassment is proposed for 

authorization or anticipated to occur 

due to their rarer occurrence in the 

project area and the unlikelihood that 

they would enter the Level A 

harassment zone and remain long 

enough to incur PTS in the rare event 

that they are encountered. No take by 

Level A harassment is proposed for 

authorization or anticipated to occur, as 

the calculated isopleths for highfrequency cetaceans are 134 m or less 

during all activities except during DTH 

for 24-in piles of limited duration where 

they are 198 m–412 m. The shutdown 

zones (Table 11) are larger for all 

calculated Level A harassment isopleths 

during all pile driving activities 

(vibratory, impact and DTH) for all 

cetaceans. 

Harbor Porpoise 

There are no density estimates of 

Harbor porpoise available in the project 

area. Although there have been no 

systematic studies or observations of 

harbor porpoises specific to Port Chester 

or Nichols Passage, there is potential for 

them to occur within the project area. 

Abundance data for harbor porpoises in 

Southeast Alaska were collected during 

18 seasonal surveys spanning 22 years, 

from 1991 to 2012 (Dahlheim et al. 

2015). During that study, a total of 81 

harbor porpoises were observed in the 

southern inland waters of Southeast 

Alaska, including Clarence Strait. The 

average density estimate for all survey 

years in Clarence Strait was 0.02 harbor 

porpoises per square kilometer. There 

does not appear to be any seasonal 

variation in harbor porpoise density for 

the inland waters of Southeast Alaska 

(Dahlheim et al. 2015). Approximately 

one to two groups of harbor porpoises 

are observed each week in group sizes 

of up to 10 animals around Driest Point, 

located 5 km (3.1 mi) north of the 

project location (L. Bethel, personal 

communication, June 11, 2020 as cited 

in the application). Therefore, 

AKDOT&PK requests and NMFS 

proposes that 2 groups of 5 harbor 

porpoises (average group size of local 

sightings) per 5 days of in-water work 

may be taken by Level B harassment. 

Expressed in another way, this is an 

average of 2 harbor porpoise per day of 

in-water work. Therefore, we estimate 

52 exposures over the course of the 

project (26 days * 2 porpoises per day 

= 52). No take by Level A harassment is 

proposed for authorization or 

anticipated to occur, as the calculated 

isopleths for high-frequency cetaceans 

are 134 m or less during all activities 

except during DTH for 24-in piles of 

limited duration where they are 198 m– 

412 m. The shutdown zones (Table 11) 

are larger for all calculated Level A 

harassment isopleths during all pile 

driving activities (vibratory, impact and 

DTH) for all cetaceans. 

Harbor Seal 

There are no density estimates of 

harbor seals available in the project 

area. Harbor seals are commonly sighted 

in the waters of the inside passages 

throughout Southeast Alaska. Surveys 

in 2015 estimated 429 (95 percent 

Confidence Interval [CI]: 102–1,203) 

harbor seals on the northwest coast of 

Annettte Island, between Metlakatla and 

Walden Point. An additional 90 (95 

percent CI: 18–292) were observed along 

the southwest coast of Annette Island, 

between Metlakatla and Tamgas Harbor 

(NOAA 2019). The Alaska Fisheries 

Science Center identifies three haulouts 

in Port Chester (less than a mile from 

the project area) and three additional 

haulouts north of Driest Point (3.7 mi 

from the project are). Abundance 

estimates for these haulouts are not 

available, but they are all denoted as 

having had more than 50 harbor seals at 

one point in time (NOAA 2020). 

However, local biologists report only 

small numbers (fewer than 10) of harbor 

seals are regularly observed in Port 

Chester. As many as 10 to 15 harbor 

seals may utilize Sylburn Harbor, north 

of Metlakatla across Driest Point (R. 

Cook, personal communication, June 5, 

2020 as cited in the application), as a 

haulout location. Therefore, 

AKDOT&PK requests and NMFS 

proposes that up to 15 harbor seals may 

be taken by Level B harassment each 

day, for a total of 390 exposures (26 

days * 15 seals per day = 390). No take 

by Level A harassment is proposed for 

authorization or anticipated to occur, as 

the calculated isopleths are 60 m or less 

during all activities except during DTH 

for 24-in piles of limited duration where 

they are 89–186 m. In addition, the 

shutdown zones (Table 11) are larger for 

all calculated Level A harassment 

isopleths during all pile driving 

activities (vibratory, impact and DTH) 

for all pinnipeds. 

Steller Sea Lion 

There are no density estimates of 

Steller sea lions available in the project 

area. Steller sea lions are common 

within the project area; however, 

systematic counts or surveys have not 

been completed in the area directly 

surrounding Metlakatla. Three haulouts 

are located within 150 km (93 mi) of the 

project area (Fritz et al. 2016a); the 

nearest documented haulout is West 

Rock, about 45 km (28 mi) south of 

Metlakatla. West Rock had a count of 

703 individuals during a June 2017 

survey and 1,101 individuals during a 

June 2019 survey (Sweeney et al. 2017, 

2019). Aerial surveys occurred 

intermittently between 1994 and 2015, 

and averaged 982 adult Steller sea lions 

(Fritz et al., 2016b). Anecdotal evidence 

indicate that 3 to 4 Steller sea lions 

utilize a buoy as a haulout near the 

entrance of Port Chester, about 3.2 km 

(2 mi) from the project location (L. 

Bethel, personal communication, June 

11, 2020 as cited in the application). 

Steller sea lions are not known to 


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congregate near the cannery in 

Metlakatla. Anecdotal evidence suggests 

that the species assemblages and 

abundance in Metlakatla are similar to 

Tongass Narrows where 20 sea lions are 

estimated each day during July through 

September. A recent monitoring report 

for Tongass Narrows reported 41 

individual sightings of Steller sea lions 

with 9 takes by Level B harassment in 

May 2021. Therefore to be conservative, 

AKDOT&PF requests and NMFS 

proposes two groups of 10 Steller sea 

lions (20 Steller sea lions) may be taken 

by Level B harassment for a total of 520 

Steller sea lions (26 days * 20 sea lions 

per day = 520). No take by Level A 

harassment is proposed or anticipated to 

occur as the largest Level A isopleth 

calculated was 13.5 m during DTH of 

24-in piles and the remaining isopleths 

were less than 10 m. In addition, the 

shutdown zones (Table 11) are larger for 

all calculated Level A harassment 

isopleths during all pile driving 

activities (vibratory, impact and DTH) 

for all pinnipeds. 

Table 10 below summarizes the 

proposed estimated take for all the 

species described above as a percentage 

of stock abundance. 

TABLE 10—PROPOSED TAKE ESTIMATES AS A PERCENTAGE OF STOCK ABUNDANCE

Species Stock 

(NEST) 

Level B 

harassment 

Percent 

of stock 

Minke Whale ............................................ Alaska (N/A) ............................................ 12 N/A. 

Humpback Whale .................................... Central North Pacific (10,103) ................. 104 Less than 1 percent. 

Killer Whale ............................................. Alaska Resident (2,347) ..........................

Northern Resident (302) ..........................

West Coast Transient (349) ....................

15 0.6 a. 

5.0 a. 

4.3 a. 

Pacific White-Sided Dolphin .................... North Pacific (26,880) ............................. 92 Less than 1 percent. 

Dall’s Porpoise ......................................... Alaska (83,400) b ..................................... 30 Less than 1 percent. 

Harbor Porpoise ...................................... Southeast Alaska (NA) ............................ 52 NA. 

Harbor Seal ............................................. Clarence Strait (27,659) .......................... 390 1.4. 

Steller Sea Lion ....................................... Eastern U.S. (43,201) ............................. 520 1.2. 

aTake 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. b Jefferson et al. 2019 presents the first abundance estimates for Dall’s porpoise in the waters of Southeast Alaska with highest abundance recorded in spring (N = 5,381, CV = 25.4 percent), lower numbers in summer (N = 2,680, CV = 19.6 percent), and lowest in fall (N = 1,637, CV = 

23.3 percent). However, NMFS currently recognizes a single stock of Dall’s porpoise in Alaskan waters and an estimate of 83,400 Dall’s porpoises is used by NMFS for the entire stock (Muto et al., 2020). 

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 such 

activity, and other means of effecting 

the least practicable impact on such 

species or stock and its habitat, paying 

particular attention to rookeries, mating 

grounds, and areas of similar 

significance, and on the availability of 

such species or stock for taking for 

certain subsistence uses (latter not 

applicable for this action). 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 such 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, we carefully consider two 

primary factors: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure(s) is 

expected to reduce impacts to marine 

mammals, marine mammal species or 

stocks, and their habitat. This considers 

the nature of the potential adverse 

impact being mitigated (likelihood, 

scope, range). It further considers the 

likelihood that the measure will be 

effective if implemented (probability of 

accomplishing the mitigating result if 

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, 

impact on operations, and, in the case 

of a military readiness activity, 

personnel safety, practicality of 

implementation, and impact on the 

effectiveness of the military readiness 

activity. 

General 

The AKDOT&PF would follow 

mitigation procedures as outlined in 

their Marine Mammal Monitoring Plan 

and as described below. In general, if 

poor environmental conditions restrict 

visibility full visibility of the shutdown 

zone, pile driving installation and 

removal as well as DTH would be 

delayed. 

Training 

The AKDOT&PF must ensure that 

construction supervisors and crews, the 

monitoring team, and relevant 

AKDOT&PF staff are trained prior to the 

start of construction activity subject to 

this IHA, 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. 

Avoiding Direct Physical Interaction 

The AKDOT&PF must avoid direct 

physical interaction with marine 

mammals during construction activity. 

If a marine mammal comes within 10 m 

of such activity, operations must cease 

and vessels must reduce speed to the 

minimum level required to maintain 

steerage and safe working conditions, as 

necessary to avoid direct physical 

interaction. 

Shutdown Zones 

For all pile driving/removal and DTH 

activities, the AKDOT&PF would 

establish a shutdown zone for a marine 

mammal species that is greater than its 

corresponding Level A harassment zone 

(Table 11). 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). The 

shutdown zones are larger than all the 

calculated Level A harassment isopleths 


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for all pile driving/removal and DTH 

activities for cetaceans and pinnipeds. 

TABLE 11—PILE DRIVING SHUTDOWN ZONES DURING PROJECT ACTIVITIES

Activity Pile diameter Pile type or 

number of piles 

Shutdown distance 

(meters) 

Cetaceans Pinnipeds 

Vibratory Installation/Removal ........ 16- and 24-in .................................. Battered and Plumb ....................... 50 50 

DTH ................................................ 24-in ............................................... Temporary ......................................

Battered, Permanent ......................

Plumb, Permanent .........................

200 

260 

415 

200 

120 

200 

DTH ................................................ 8-in ................................................. Permanent ...................................... 100 50 

Impact ............................................. 24-in ............................................... 3 piles ............................................. 135 

2 piles ............................................. 100 

1 pile .............................................. 100 

Soft Start 

The AKDOT&PF must use soft start 

techniques when impact pile driving. 

Soft start requires contractors to provide 

an initial set of three strikes from the 

hammer at reduced energy, followed by 

a 30-second waiting period. Then two 

subsequent reduced-energy strike sets 

would occur. 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. Soft start is not required during 

vibratory pile driving and removal 

activities. 

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 in the proposed action area. 

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: 

D Occurrence of marine mammal 

species or stocks in the area in which 

take is anticipated (e.g., presence, 

abundance, distribution, density); 

D 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 

action; or (4) biological or behavioral 

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

feeding areas); 

D Individual marine mammal 

responses (behavioral or physiological) 

to acoustic stressors (acute, chronic, or 

cumulative), other stressors, or 

cumulative impacts from multiple 

stressors; 

D How anticipated responses to 

stressors impact either: (1) Long-term 

fitness and survival of individual 

marine mammals; or (2) populations, 

species, or stocks; 

D Effects on marine mammal habitat 

(e.g., marine mammal prey species, 

acoustic habitat, or other important 

physical components of marine 

mammal habitat); and 

D Mitigation and monitoring 

effectiveness. 

Monitoring Zones 

The AKDOT&PF will conduct 

monitoring to include the area within 

the Level B harassment presented in 

Table 9. Monitoring will include all 

areas where SPLs are equal to or exceed 

120 dB rms (for vibratory pile driving/ 

removal and DTH) and 160 dB rms (for 

impact pile driving). These zones 

provide utility for monitoring 

conducted for mitigation purposes (i.e., 

shutdown zone monitoring) by 

establishing monitoring protocols for 

areas adjacent to the shutdown zones. 

Monitoring of the Level B harassment 

zones enables observers to be aware of 

and communicate the presence of 

marine mammals in the project area, but 

outside the shutdown zone, and thus 

prepare for potential shutdowns of 

activity. 

Pre-Start Clearance Monitoring 

Pre-start clearance monitoring must 

be conducted during periods of 

visibility sufficient for the lead PSO to 

determine the shutdown zones clear of 

marine mammals. Pile driving and DTH 

may commence when the determination 

is made. 

Visual Monitoring 

Monitoring must take place from 30 

minutes (min) prior to initiation of pile 

driving and DTH activity (i.e., pre-start 

clearance monitoring) through 30 min 

post-completion of pile driving and 

DTH activity. If a marine mammal is 

observed entering or within the 

shutdown zones, pile driving and DTH 

activity must be delayed or halted. If 

pile driving or DTH 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 or 15 min have passed 

without re-detection of the animal. Pile 

driving and DTH activity must be halted 

upon observation of either a species for 

which incidental take is not authorized 

or a species for which incidental take 

has been authorized but the authorized 

number of takes has been met, entering 

or within the harassment zone. 

PSO Monitoring Requirements and 

Locations 

The AKDOT&PF must establish 

monitoring locations as described in the 

Marine Mammal Monitoring Plan. PSOs 


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will be responsible for monitoring, the 

shutdown zones, the Level B 

harassment zones, and the pre-clearance 

zones, as well as effectively 

documenting Level B harassment take. 

As described in more detail in the 

Reporting section below, they will also 

(1) document the frequency at which 

marine mammals are present in the 

project area, (2) document behavior and 

group composition (3) record all 

construction activities, and (4) 

document observed reactions (changes 

in behavior or movement) of marine 

mammals during each sighting. 

Observers will monitor for marine 

mammals during all in-water pile 

installation/removal and DTH 

associated with the project. The 

AKDOT&PF must monitor the project 

area to the extent possible based on the 

required number of PSOs, required 

monitoring locations, and 

environmental conditions. Monitoring 

would be conducted by PSOs from land. 

For all pile driving and DTH activities, 

a minimum of one observer must be 

assigned to each active pile driving and 

DTH location to monitor the shutdown 

zones. Two PSOs must be onsite during 

all in-water activities and will monitor 

from the best vantage point. Due to the 

remote nature of the area, the PSOs will 

meet with the future designated 

Contractor and AKDOT&PF to 

determine the most appropriate 

observation location(s) for monitoring 

during pile installation and removal. 

These observers must record all 

observations of marine mammals, 

regardless of distance from the pile 

being driven or during DTH. 

In addition, PSOs will work in shifts 

lasting no longer than 4 hrs with at least 

a 1-hr break between shifts, and will not 

perform duties as a PSO for more than 

12 hrs in a 24-hr period (to reduce PSO 

fatigue). 

Monitoring of pile driving shall be 

conducted by qualified, NMFSapproved PSOs. The AKDOT&PF shall 

adhere to the following conditions when 

selecting PSOs: 

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

construction personnel) and have no 

other assigned tasks during monitoring 

periods; 

D At least one PSO must have prior 

experience performing the duties of a 

PSO during construction activities 

pursuant to a NMFS-issued incidental 

take authorization; 

D Other PSOs may substitute other 

relevant experience, education (degree 

in biological science or related field), or 

training; 

D Where a team of three PSOs are 

required, a lead observer or monitoring 

coordinator shall be designated. The 

lead observer must have prior 

experience performing the duties of a 

PSO during construction activity 

pursuant to a NMFS-issued incidental 

take authorization; and 

D PSOs must be approved by NMFS 

prior to beginning any activity subject to 

this IHA. 

The AKDOT&PF shall ensure that the 

PSOs have the following additional 

qualifications: 

D Visual acuity in both eyes 

(correction is permissible) sufficient for 

discernment of moving targets at the 

water’s surface with ability to estimate 

target size and distance; use of 

binoculars may be necessary to correctly 

identify the target; 

D Experience and ability to conduct 

field observations and collect data 

according to assigned protocols; 

D Experience or training in the field 

identification of marine mammals, 

including the identification of 

behaviors; 

D Sufficient training, orientation, or 

experience with the construction 

operation to provide for personal safety 

during observations; 

D 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 

D 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. 

Final Report 

The AKDOT&PF will submit a draft 

report to NMFS on all monitoring 

conducted under this IHA within 90 

calendar days of the completion of 

monitoring or 60 calendar days prior to 

the requested issuance of any 

subsequent IHA for construction activity 

at the same location, whichever comes 

first. A final report must be prepared 

and submitted within 30 days following 

resolution of any NMFS comments on 

the draft report. If no comments are 

received from NMFS within 30 days of 

receipt of the draft report, the report 

shall be considered final. All draft and 

final marine mammal monitoring 

reports must be submitted to 

PR.ITP.MonitoringReports@noaa.gov 

and ITP.Egger@noaa.gov. The report 

must contain the informational elements 

described in the Marine Mammal 

Monitoring Plan and, at minimum, must 

include: 

D Dates and times (begin and end) of 

all marine mammal monitoring; 

D Construction activities occurring 

during each daily observation period, 

including: 

Æ How many and what type of piles 

were driven and by what method (e.g., 

impact, vibratory, DTH); 

Æ Total duration of driving time for 

each pile (vibratory driving) and 

number of strikes for each pile (impact 

driving); and 

Æ For DTH, duration of operation for 

both impulsive and non-pulse 

components. 

D PSO locations during marine 

mammal monitoring; 

D 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; 

D Upon observation of a marine 

mammal, the following information: 

Æ PSO who sighted the animal and 

PSO location and activity at time of 

sighting; 

Æ Time of sighting; 

Æ Identification of the animal (e.g., 

genus/species, lowest possible 

taxonomic level, or unidentified), PSO 

confidence in identification, and the 

composition of the group if there is a 

mix of species; 

Æ Distance and bearing of each 

marine mammal observed to the pile 

being driven for each sighting (if pile 

driving and DTH was occurring at time 

of sighting); 

Æ Estimated number of animals (min/ 

max/best); 

Æ Estimated number of animals by 

cohort (adults, juveniles, neonates, 

group composition etc.; 

Æ Animal’s closest point of approach 

and estimated time spent within the 

harassment zone; and 

Æ Description of any marine mammal 

behavioral observations (e.g., observed 

behaviors such as feeding or traveling), 

including an assessment of behavioral 

responses to the activity (e.g., no 

response or changes in behavioral state 

such as ceasing feeding, changing 

direction, flushing, or breaching). 

D Detailed information about 

implementation of any mitigation (e.g., 

shutdowns and delays), a description of 

specific actions that ensued, and 

resulting changes in behavior of the 

animal, if any; and 

D All PSO datasheets and/or raw 

sightings data. 


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Reporting of Injured or Dead Marine 

Mammals 

In the event that personnel involved 

in the construction activities discover 

an injured or dead marine mammal, the 

AKDOT&PF must report the incident to 

NMFS Office of Protected Resources 

(OPR) (PR.ITP.MonitoringReports@

noaa.gov), NMFS (301–427–8401) and 

to the Alaska regional stranding network 

(877–925–7773) as soon as feasible. If 

the death or injury was clearly caused 

by the specified activity, the 

AKDOT&PF must immediately cease the 

specified activities until NMFS OPR 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 

this IHA. The AKDOT&PF must not 

resume their activities until notified by 

NMFS. The report must include the 

following information: 

D Time, date, and location (latitude/ 

longitude) of the first discovery (and 

updated location information if known 

and applicable); 

D Species identification (if known) or 

description of the animal(s) involved; 

D Condition of the animal(s) 

(including carcass condition if the 

animal is dead); 

D Observed behaviors of the 

animal(s), if alive; 

D If available, photographs or video 

footage of the animal(s); and 

D 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 responses (e.g., intensity, 

duration), the context of any responses 

(e.g., critical reproductive time or 

location, migration), 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’s 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 environmental 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). 

As stated in the proposed mitigation 

section, shutdown zones that are larger 

than the Level A harassment zones will 

be implemented, which, in combination 

with the fact that the zones are small to 

begin with, is expected to avoid the 

likelihood of Level A harassment for 

marine mammals species. 

Exposures to elevated sound levels 

produced during pile driving activities 

may cause behavioral responses by an 

animal, but they are expected to be mild 

and temporary. Effects on individuals 

that are taken by Level B harassment, on 

the basis of reports in the literature as 

well as monitoring from other similar 

activities, will likely be limited to 

reactions such as increased swimming 

speeds, increased surfacing time, or 

decreased foraging (if such activity were 

occurring) (e.g., Thorson and Reyff, 

2006; Lerma, 2014). Most likely, 

individuals will simply move away 

from the sound source and be 

temporarily displaced from the areas of 

pile driving, although even this reaction 

has been observed primarily only in 

association with impact pile driving. 

These reactions and behavioral changes 

are expected to subside quickly when 

the exposures cease. 

During all impact driving, 

implementation of soft start procedures 

and monitoring of established shutdown 

zones will be required, significantly 

reducing the possibility of injury. Given 

sufficient notice through use of soft start 

(for impact driving), marine mammals 

are expected to move away from an 

irritating sound source prior to it 

becoming potentially injurious. In 

addition, PSOs will be stationed within 

the action area whenever pile driving/ 

removal and DTH activities are 

underway. Depending on the activity, 

the AKDOT&PF will employ the use of 

two PSOs to ensure all monitoring and 

shutdown zones are properly observed. 

The project would likely not 

permanently impact any marine 

mammal habitat since the project will 

occur within the same footprint as 

existing marine infrastructure. The 

nearshore and intertidal habitat where 

the project will occur is an area of 

relatively high marine vessel traffic. The 

closest pinniped haulouts are used by 

harbor seals and are less than a mile 

from the project area; however, impacts 

to fitness of individuals is likely low 

(due to short duration of the project) 

and would not produce population-level 

impacts. There are no other biologically 

important areas for marine mammals 

near the project area. In addition, 

impacts to marine mammal prey species 

are expected to be minor and temporary. 

Overall, the area impacted by the project 

is very small compared to the available 

habitat around Metlakatla. The most 

likely impact to prey will be temporary 

behavioral avoidance of the immediate 

area. During pile driving/removal and 

DTH activities, it is expected that fish 

and marine mammals would 

temporarily move to nearby locations 

and return to the area following 

cessation of in-water construction 

activities. Therefore, indirect effects on 

marine mammal prey during the 

construction are not expected to be 

substantial. 

In summary and as described above, 

the following factors primarily support 

our preliminary determination that the 

impacts resulting from this activity are 

not expected to adversely affect the 

species or stock through effects on 

annual rates of recruitment or survival: 

D No mortality is anticipated or 

authorized; 

D No take by Level A harassment is 

expected or authorized; 

D Minimal impacts to marine 

mammal habitat/prey are expected; 

D The action area is located and 

within an active marine commercial 

area; 

D Anticipated incidents of Level B 

harassment consist of, at worst, 

temporary modifications in behavior; 

and 

D The required mitigation measures 

(i.e. shutdown zones) are expected to be 

effective in reducing the effects of the 

specified activity. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

proposed monitoring and mitigation 

measures, NMFS preliminarily finds 

that the total marine mammal take from 

the proposed activity will have a 

negligible impact on all affected marine 

mammal species or stocks. 

Small Numbers 

As noted above, only small numbers 

of incidental take may be authorized 

under Section 101(a)(5)(A) and (D) of 

the MMPA for specified activities other 

than military readiness activities. The 

MMPA does not define small numbers 


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Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 34227 

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. 

Take of six of the marine mammal 

stocks proposed will comprise at most 

approximately 1.4 percent or less of the 

stock abundance. There are no official 

stock abundances for harbor porpoise 

and minke whales; however, as 

discussed in greater detail in the 

Description of Marine Mammals in the 

Area of Specified Activities, we believe 

for the abundance information that is 

available, the estimated takes are likely 

small percentages of the stock 

abundance. For harbor porpoise, the 

abundance for the Southeast Alaska 

stock is likely more represented by the 

aerial surveys that were conducted as 

these surveys had better coverage and 

were corrected for observer bias. Based 

on this data, the estimated take could 

potentially be approximately 4 percent 

of the stock abundance. However, this is 

unlikely and the percentage of the stock 

taken is likely lower as the proposed 

take estimates are conservative and the 

project occurs in a small footprint 

compared to the available habitat in 

Southeast Alaska. For minke whales, in 

the northern part of their range they are 

believed to be migratory and so few 

minke whales have been seen during 

three offshore Gulf of Alaska surveys 

that a population estimate could not be 

determined. With only twelve proposed 

takes for this species, the percentage of 

take in relation to the stock abundance 

is likely to be very small. 

Based on the analysis contained 

herein of the proposed activity 

(including the proposed mitigation and 

monitoring measures) and the 

anticipated take of marine mammals, 

NMFS preliminarily finds that small 

numbers of marine mammals will 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. 

The project area does not spatially 

overlap any known subsistence hunting. 

The project area is a developed area 

with regular marine vessel traffic. 

However, the AKDOT&PF plans to 

provide advance public notice of 

construction activities to reduce 

construction impacts on local residents, 

adjacent businesses, and other users of 

Port Chester and nearby areas. This will 

include notification to nearby Alaska 

Native tribes that may have members 

who hunt marine mammals for 

subsistence. Currently, the Metlakatla 

Indian Community does not authorize 

the harvest of marine mammals for 

subsistence use (R. Cook, personal 

communication, June 5, 2020 as cited in 

the application). 

The proposed project is not likely to 

adversely impact the availability of any 

marine mammal species or stocks that 

are commonly used for subsistence 

purposes or to impact subsistence 

harvest of marine mammals in the 

region because construction activities 

are localized and temporary; mitigation 

measures will be implemented to 

minimize disturbance of marine 

mammals in the project area. 

Accordingly, NMFS has preliminarily 

determined that there will not be an 

unmitigable adverse impact on 

subsistence uses from the AKDOT&PF’s 

proposed activities. 

Endangered Species Act (ESA) 

Section 7(a)(2) of the Endangered 

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

1531 et seq.) requires that each Federal 

agency insure that any action it 

authorizes, funds, or carries out is not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or result in the 

destruction or adverse modification of 

designated critical habitat. To ensure 

ESA compliance for the issuance of 

IHAs, NMFS consults internally 

whenever we propose to authorize take 

for endangered or threatened species, in 

this case with the Alaska Regional 

Office (AKRO). 

NMFS is proposing to authorize take 

of the Mexico DPS of humpback whales, 

which are listed under the ESA. The 

Permit and Conservation Division has 

requested initiation of Section 7 

consultation with the AKRO for the 

issuance of this IHA. NMFS will 

conclude the ESA consultation prior to 

reaching a determination regarding the 

proposed issuance of the authorization. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

an IHA to the AKDOT&PF for 

conducting for the proposed pile driving 

and removal activities as well as DTH 

during construction of the Metlakatla 

Seaplane Facility Refurbishment 

Project, Metlakatla, Alaska for one year, 

beginning August 2021, provided the 

previously mentioned mitigation, 

monitoring, and reporting requirements 

are incorporated. A draft of the 

proposed IHA can be found at https:// 

www.fisheries.noaa.gov/permit/ 

incidental-take-authorizations-undermarine-mammal-protection-act. 

Request for Public Comments 

We request comment on our analyses, 

the proposed authorization, and any 

other aspect of this notice of proposed 

IHA for the proposed pile driving and 

removal activities as well as DTH during 

construction of the Metlakatla Seaplane 

Facility Refurbishment Project. We also 

request at this time, comments on the 

potential for Renewal of this proposed 

IHA as described in the paragraph 

below. Please include with your 

comments any supporting data or 

literature citations to help inform 

decisions on the request for this IHA or 

a subsequent Renewal IHA. 

On a case-by-case basis, NMFS may 

issue a one-time, 1-year Renewal IHA 

following notice to the public providing 

an additional 15 days for public 

comments when (1) up to another year 

of identical or nearly identical, or nearly 

identical, activities as described in the 

Description of Proposed Activities 

section of this notice is planned or (2) 

the activities as described in the 

Description of Proposed Activities 

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: 

D 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). 


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34228 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Notices 

D 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); and 

(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: June 23, 2021. 

Catherine Marzin, 

Acting Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2021–13790 Filed 6–28–21; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XB193] 

Endangered and Threatened Species; 

Notice of Initiation of a 5-Year Review 

of the Kemp’s Ridley Sea Turtle 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce, and Fish and Wildlife 

Service (USFWS), Interior. 

ACTION: Notice of initiation of 5-year 

review; request for information. 

SUMMARY: NMFS and USFWS announce 

the initiation of a 5-year review for the 

Kemp’s ridley sea turtle (Lepidochelys 

kempii). We are required by the 

Endangered Species Act (ESA) to 

conduct 5-year reviews to ensure that 

the species’ listing status remains 

accurate. The 5-year review must be 

based on the best scientific and 

commercial data available at the time of 

the review. We request submission of 

any such information on the Kemp’s 

ridley, particularly information on the 

status, threats, and recovery of the 

species that has become available since 

the last 5-year review was published in 

July of 2015. 

DATES: To allow us adequate time to 

conduct this review, we must receive 

your information no later than August 

30, 2021. 

ADDRESSES: You may submit 

information on this document, 

identified by NOAA–NMFS–2021–0063, 

by the following method: 

• Electronic Submission: Submit 

electronic information via the Federal eRulemaking Portal. Go to 

www.regulations.gov and enter NOAA– 

NMFS–2021–0063 in the Search box. 

Click on the ‘‘Comment’’ icon and 

complete the required fields. Enter or 

attach your comments. 

Instructions: Comments sent by any 

other method, to any other address or 

individual, or received after the end of 

the specified period, may not be 

considered. All comments received are 

a part of the public record and will 

generally be posted for public viewing 

on www.regulations.gov without change. 

All personal identifying information 

(e.g., name, address, etc.), confidential 

business information, or otherwise 

sensitive or protected information 

submitted voluntarily by the sender will 

be publicly accessible. NMFS will 

accept anonymous submissions (enter 

‘‘N/A’’ in the required fields if you wish 

to remain anonymous). 

FOR FURTHER INFORMATION CONTACT: 

Jennifer Schultz, by phone at (301) 427– 

8443 or Jennifer.Schultz@noaa.gov. 

SUPPLEMENTARY INFORMATION: This 

notice announces our 5-year review of 

the Kemp’s ridley, which is listed as an 

endangered species under the ESA. 

Section 4(c)(2)(A) of the ESA requires us 

to conduct a review of listed species at 

least once every 5 years. On the basis of 

that review, we are required to 

determine whether a listed species 

should be removed from the list (i.e., 

delisted) or reclassified from 

endangered to threatened or from 

threatened to endangered (16 U.S.C. 

1533(c)(2)(B)). The regulations in 50 

CFR 424.21 require that we publish a 

notice in the Federal Register 

announcing species under active 

review. 

Background information on the 

species is available on the NMFS 

website at: https://

www.fisheries.noaa.gov/species/kempsridley-turtle. 

Public Solicitation of New Information 

To ensure that the review is complete 

and based on the best available 

scientific and commercial information, 

we are soliciting new information from 

the public, governmental agencies, 

Tribes, the scientific community, 

industry, environmental entities, and 

any other interested parties concerning 

the status of the species. Categories of 

requested information include: (1) 

Species biology including, but not 

limited to, population trends, 

distribution, abundance, demographics, 

and genetics; (2) habitat conditions 

including, but not limited to, amount, 

distribution, and important features for 

conservation; (3) status and trends of 

threats to the species and its habitats; (4) 

conservation measures that have been 

implemented that benefit the species, 

including monitoring data 

demonstrating effectiveness of such 

measures; (5) need for additional 

conservation measures; and (6) other 

new information, data, or corrections 

including, but not limited to, taxonomic 

or nomenclatural changes and improved 

analytical methods for evaluating 

extinction risk. 

If you wish to provide information for 

the review, you may submit your 

information and materials electronically 

(see ADDRESSES section). We request that 

all information be accompanied by 

supporting documentation such as 

maps, bibliographic references, or 

reprints of pertinent publications. 

Authority: 16 U.S.C. 1531 et seq. 

Dated: June 23, 2021. 

Margaret H. Miller, 

Acting Chief, Endangered Species Division, 

Office of Protected Resources, National 

Marine Fisheries Service. 

[FR Doc. 2021–13768 Filed 6–28–21; 8:45 am] 

BILLING CODE 3510–22–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XB157] 

Fisheries of the South Atlantic; 

Southeast Data, Assessment, and 

Review (SEDAR); Public Meeting 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice of SEDAR webinar II for 

SEDAR Procedural Workshop 8: Fishery 

Independent Index Development Under 

Changing Survey Design. 

SUMMARY: The SEDAR Procedural 

Workshop 8 for Fishery Independent 

Index Development will consist of a 

series of webinars, and an in-person 


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