Notice2021-13790
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
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
June 29, 2021
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
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.
Full Text
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<title>Federal Register, Volume 86 Issue 122 (Tuesday, June 29, 2021)</title>
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[Federal Register Volume 86, Number 122 (Tuesday, June 29, 2021)]
[Notices]
[Pages 34203-34228]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[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 <a href="/cdn-cgi/l/email-protection#743d20245a3113131106341a1b15155a131b02"><span class="__cf_email__" data-cfemail="1b524f4b355e7c7c7e695b75747a7a357c746d">[email protected]</span></a>.
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 <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> 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: <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a>. 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)
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Pile Installation
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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
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Pile Removal
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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
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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; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports</a>) and more general information about these
species (e.g., physical and behavioral descriptions) may be found on
NMFS's website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
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: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>).
[[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)
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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).
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Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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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).
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Order Carnivora--Superfamily Pinnipedia
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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).
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\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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports</a>-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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>).
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
<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>). 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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>).
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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>).
[[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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>).
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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>).
[[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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>). 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 <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements">https://www.fisheries.noaa.gov/action/incidental-take-authorization-alaska-department-transportation-ferry-berth-improvements</a>). 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 <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
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 * log<INF>10</INF>(R<INF>1</INF>/R<INF>2</INF>),
where:
B = transmission loss coefficient (assumed to be 15)
R<INF>1</INF> = the distance of the modeled SPL from the driven
pile, and
R<INF>2</INF> = 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
<a href="/cdn-cgi/l/email-protection#6e3e3c40273a3e40230100071a011c0700093c0b1e011c1a1d2e00010f0f40090118"><span class="__cf_email__" data-cfemail="4e1e1c60071a1e60032120273a213c2720291c2b3e213c3a3d0e20212f2f60292138">[email protected]</span></a> and <a href="/cdn-cgi/l/email-protection#f5bca1a5dbb092929087b59b9a9494db929a83"><span class="__cf_email__" data-cfemail="521b06027c1735353720123c3d33337c353d24">[email protected]</span></a>. 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)
(<a href="/cdn-cgi/l/email-protection#9bcbc9b5d2cfcbb5d6f4f5f2eff4e9f2f5fcc9feebf4e9efe8dbf5f4fafab5fcf4ed"><span class="__cf_email__" data-cfemail="3e6e6c10776a6e10735150574a514c5750596c5b4e514c4a4d7e50515f5f10595148">[email protected]</span></a>), 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 <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a>.
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
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.