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, 34203-34228 [2021-13790]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 86, Number 122 (Tuesday, June 29, 2021)]
[Notices]
[Pages 34203-34228]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-13790]



[[Page 34203]]

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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.

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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 [email protected].
    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-under-marine-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-under-marine-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.

[[Page 34204]]

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 Whales-Hyder 
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[deg]7'50.30'' North, 131[deg]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

[[Page 34205]]

[GRAPHIC] [TIFF OMITTED] TN29JN21.277

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 multiple-float 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.

[[Page 34206]]

    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
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                                                                                                          DTH pile
                                                                  Impact                  DTH pile      installation      Total
                                                                  strikes   Vibratory   installation      (tension     duration of  Piles per
    Pile diameter and type     Number of     Rock     Tension    per pile    duration   (rock socket)      anchor)       activity      day       Total
                                  piles    sockets    anchors    (duration   per pile   duration per    duration per     per pile    (range)      days
                                                                    in      (minutes)       pile            pile         (hours)
                                                                 minutes)                 (minutes)       (minutes)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Pile Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in Steel Plumb Piles                4          4          4     20 (15)         15             180             120          5.5  0.5 (0-1)          8
 (Permanent).................
24-in Steel Batter Piles               2          2          2     20 (15)         15              90             120            4  0.5 (0-1)          4
 (Permanent).................
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/marine-mammal-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/draft-marine-mammal-stock-assessment-reports).

[[Page 34207]]



                                                  Table 2--Marine Mammal Occurrence in the Project Area
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                                                                                      ESA/MMPA status;   Stock abundance (CV,
            Common name                  Scientific name              Stock           strategic (Y/N)      Nmin, most recent        PBR      Annual M/SI
                                                                                            \1\         abundance  survey) \2\                   \3\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Minke Whale....................  Balaenoptera            Alaska................  -, -, N            N/A (see SAR, N/A, see          UND            0
                                      acutorostrata.                                                     SAR).
    Humpback Whale.................  Megaptera novaeangliae  Central N Pacific.....  -, -, Y            10,103 (0.3, 7,891,              83           26
                                                                                                         2006).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer Whale...................  Orcinus orca..........  Alaska Resident.......  -, -, N            2,347 (N/A, 2347,                24            1
                                                                                                         2012).
                                                             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          N Pacific.............  -, -, N            26,880 (N/A, N/A,               UND            0
                                      obliquidens.                                                       1990).
Family Phocoenidae (porpoises):
    Dall's Porpoise................  Phocoenoides dalli....  AK....................  -, -, N            83,400 (0.097, N/A,             UND           38
                                                                                                         1991).
    Harbor Porpoise................  Phocoena phocoena.....  Southeast Alaska        -, -, Y            see SAR (see SAR, see       see SAR           34
                                                              Inland waters.                             SAR, 2012).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         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,             2592          112
                                                                                                         43,201, 2017).
Family Phocidae (earless seals):
    Harbor Seal....................  Phoca vitulina........  Clarence Strait.......  -, -, N            27,659 (see SAR,                746           40
                                                                                                         24,854, 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered 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-assessment-reports-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]:
\3\ These 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-alaska-department-transportation-ferry-berth-improvements).

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 near-ice-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

[[Page 34208]]

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, open-strait 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-alaska-department-transportation-ferry-berth-improvements). 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-alaska-department-transportation-ferry-berth-improvements).

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[deg] North and 47[deg] 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 Ni[ntilde]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-alaska-department-transportation-ferry-berth-improvements).

[[Page 34209]]

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-alaska-department-transportation-ferry-berth-improvements).

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-alaska-department-transportation-ferry-berth-improvements).

[[Page 34210]]

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-alaska-department-transportation-ferry-berth-improvements). 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[deg] 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-alaska-department-transportation-ferry-berth-improvements). 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 low-frequency 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.

[[Page 34211]]



                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen  7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true   275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)    50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)   60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* 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 
(Hemil[auml] 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 ([mu]Pa)), 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 [mu]Pa), while the received level is the SPL at the 
listener's position (referenced to 1 [mu]Pa).
    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 [mu]Pa\2\-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

[[Page 34212]]

(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 non-pulsed 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 non-
impulsive, 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; G[ouml]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

[[Page 34213]]

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

[[Page 34214]]

(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

[[Page 34215]]

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 five-day 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-
pituitary-adrenal 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 high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete

[[Page 34216]]

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.

[[Page 34217]]

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 [mu]Pa (rms) 
for continuous (e.g., vibratory pile driving and DTH) and above 160 dB 
re 1 [mu]Pa (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 [mu]Pa (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

[[Page 34218]]

potential for noise to affect auditory sensitivity by:
    [ssquf] Dividing sound sources into two groups (i.e., impulsive and 
non-impulsive) based on their potential to affect hearing sensitivity;
    [ssquf] 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
    [ssquf] 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-technical-guidance.
    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]
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds \*\ (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 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 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. 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 
(free-field) 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

[[Page 34219]]

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                         dB rms
 DTH).
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     B, C, F, G.
                                                                                            72) \b\.
8-in DTH \c\.............................                        166                       NMFS \c\                     ................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
 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.................  ................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Federal 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.
\c\ Tension 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
-----------------------------------------------------------------------------------------------------------------
                                                                                                  24-in plumb/
                                                            16-in piles        24-in  piles       batter piles
                                                             (removal)          temporary          permanent
                                                                            (install/removal)      (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      8-in pile       8-in pile       8-in pile      24-in pile      24-in pile      24-in pile
                                            (permanent)        (DTH)           (DTH)           (DTH)           (DTH)           (DTH)           (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

[[Page 34220]]

 
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                  10              10              10              10              10              10              10
 (meters) +.............................
--------------------------------------------------------------------------------------------------------------------------------------------------------


                     Table 8--NMFS Technical Guidance (2020) User Spreadsheet Outputs To Calculate Level A Harassment PTS Isopleths
--------------------------------------------------------------------------------------------------------------------------------------------------------
                        User spreadsheet output                                                      PTS isopleths (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       Level A harassment
                                                                       ---------------------------------------------------------------------------------
               Activity                   Sound source level at 10 m     Low-frequency   Mid-frequency   High-frequency
                                                                           cetaceans       cetaceans        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             161 SPL........................            10.8             1.0              16.0             6.6             0.5
 installation and removal.
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  181 SEL/193 SPL................           112.6             4.0             134.1            60.3             4.4
 piles a day).
24-in steel permanent installation (2  181 SEL/193 SPL................            85.9             3.1             102.3            46.0             3.3
 piles a day).
24-in steel permanent installation (1  181 SEL/193 SPL................            54.1             1.9              64.5            29.0             2.1
 piles a day).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                           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
----------------------------------------------------------------------------------------------------------------
                                                                                        Level B harassment zone
                Activity                        Received level at 10 meters (m)                  (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

[[Page 34221]]

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 x 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 low-frequency 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

[[Page 34222]]

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 
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 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

[[Page 34223]]

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
----------------------------------------------------------------------------------------------------------------
                                                                          Level B
                 Species                         Stock (NEST)           harassment         Percent of stock
----------------------------------------------------------------------------------------------------------------
Minke Whale.............................  Alaska (N/A)..............              12  N/A.
Humpback Whale..........................  Central North Pacific                  104  Less than 1 percent.
                                           (10,103).
Killer Whale............................  Alaska Resident (2,347)...              15  0.6 a.
                                          Northern Resident (302)...                  5.0 a.
                                          West Coast Transient (349)                  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.
----------------------------------------------------------------------------------------------------------------
a Take 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

[[Page 34224]]

for all pile driving/removal and DTH activities for cetaceans and 
pinnipeds.

                         Table 11--Pile Driving Shutdown Zones During Project Activities
----------------------------------------------------------------------------------------------------------------
                                                                                    Shutdown distance (meters)
             Activity                   Pile diameter       Pile type or  number -------------------------------
                                                                  of piles           Cetaceans       Pinnipeds
----------------------------------------------------------------------------------------------------------------
Vibratory Installation/Removal....  16- and 24-in........  Battered and Plumb...              50              50
DTH...............................  24-in................  Temporary............             200             200
                                                           Battered, Permanent..             260             120
                                                           Plumb, Permanent.....             415             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:
    [ssquf] Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
    [ssquf] 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);
    [ssquf] Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
    [ssquf] How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
    [ssquf] Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
    [ssquf] 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

[[Page 34225]]

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[hyphen]hr period (to reduce PSO 
fatigue).
    Monitoring of pile driving shall be conducted by qualified, NMFS-
approved PSOs. The AKDOT&PF shall adhere to the following conditions 
when selecting PSOs:
    [ssquf] PSOs must be independent (i.e., not construction personnel) 
and have no other assigned tasks during monitoring periods;
    [ssquf] 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;
    [ssquf] Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field), or training;
    [ssquf] 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
    [ssquf] 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:
    [ssquf] 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;
    [ssquf] Experience and ability to conduct field observations and 
collect data according to assigned protocols;
    [ssquf] Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
    [ssquf] Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
    [ssquf] 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
    [ssquf] 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 
[email protected] and [email protected]. The report 
must contain the informational elements described in the Marine Mammal 
Monitoring Plan and, at minimum, must include:
    [ssquf] Dates and times (begin and end) of all marine mammal 
monitoring;
    [ssquf] Construction activities occurring during each daily 
observation period, including:
    [cir] How many and what type of piles were driven and by what 
method (e.g., impact, vibratory, DTH);
    [cir] Total duration of driving time for each pile (vibratory 
driving) and number of strikes for each pile (impact driving); and
    [cir] For DTH, duration of operation for both impulsive and non-
pulse components.
    [ssquf] PSO locations during marine mammal monitoring;
    [ssquf] 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;
    [ssquf] Upon observation of a marine mammal, the following 
information:
    [cir] PSO who sighted the animal and PSO location and activity at 
time of sighting;
    [cir] Time of sighting;
    [cir] 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;
    [cir] 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);
    [cir] Estimated number of animals (min/max/best);
    [cir] Estimated number of animals by cohort (adults, juveniles, 
neonates, group composition etc.;
    [cir] Animal's closest point of approach and estimated time spent 
within the harassment zone; and
    [cir] 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).
    [ssquf] 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
    [ssquf] All PSO datasheets and/or raw sightings data.

[[Page 34226]]

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) 
([email protected]), 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:
    [ssquf] Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    [ssquf] Species identification (if known) or description of the 
animal(s) involved;
    [ssquf] Condition of the animal(s) (including carcass condition if 
the animal is dead);
    [ssquf] Observed behaviors of the animal(s), if alive;
    [ssquf] If available, photographs or video footage of the 
animal(s); and
    [ssquf] 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., population-
level 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:
    [ssquf] No mortality is anticipated or authorized;
    [ssquf] No take by Level A harassment is expected or authorized;
    [ssquf] Minimal impacts to marine mammal habitat/prey are expected;
    [ssquf] The action area is located and within an active marine 
commercial area;
    [ssquf] Anticipated incidents of Level B harassment consist of, at 
worst, temporary modifications in behavior; and
    [ssquf] 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

[[Page 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-under-marine-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:
    [ssquf] 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).

[[Page 34228]]

    [ssquf] 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