Notice2022-02035
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass Narrows in Ketchikan, 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
February 2, 2022
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the Alaska Department of Transportation and Public Facilities (ADOT) for an Incidental Harassment Authorization (IHA) to take marine mammals incidental to the construction of four ferry berth facilities in Tongass Narrows in Ketchikan, Alaska: The Gravina Airport Ferry Layup Facility, the Gravina Freight Facility, the Revilla New Ferry Berth, and the Gravina Island Shuttle Ferry Berth Facility. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an IHA to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, 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
<html>
<head>
<title>Federal Register, Volume 87 Issue 22 (Wednesday, February 2, 2022)</title>
</head>
<body><pre>
[Federal Register Volume 87, Number 22 (Wednesday, February 2, 2022)]
[Notices]
[Pages 5980-6015]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-02035]
[[Page 5979]]
Vol. 87
Wednesday,
No. 22
February 2, 2022
Part III
Department of Commerce
-----------------------------------------------------------------------
National Oceanic and Atmospheric Administration
-----------------------------------------------------------------------
Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Ferry Berth Improvements in Tongass
Narrows in Ketchikan, Alaska; Notice
Federal Register / Vol. 87 , No. 22 / Wednesday, February 2, 2022 /
Notices
[[Page 5980]]
-----------------------------------------------------------------------
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XB709]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass
Narrows in Ketchikan, Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
-----------------------------------------------------------------------
SUMMARY: NMFS has received a request from the Alaska Department of
Transportation and Public Facilities (ADOT) for an Incidental
Harassment Authorization (IHA) to take marine mammals incidental to the
construction of four ferry berth facilities in Tongass Narrows in
Ketchikan, Alaska: The Gravina Airport Ferry Layup Facility, the
Gravina Freight Facility, the Revilla New Ferry Berth, and the Gravina
Island Shuttle Ferry Berth Facility. Pursuant to the Marine Mammal
Protection Act (MMPA), NMFS is requesting comments on its proposal to
issue an IHA to incidentally take marine mammals during the specified
activities. NMFS is also requesting comments on a possible one-time,
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 March 4,
2022.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service. Written comments should be submitted
via email to <a href="/cdn-cgi/l/email-protection#8ec7dadea0caeff8e7fdcee0e1efefa0e9e1f8"><span class="__cf_email__" data-cfemail="6d24393d43290c1b041e2d03020c0c430a021b">[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, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at
<a href="http://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">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: Leah Davis, 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, 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 the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of the takings are set forth. The definitions
of all applicable MMPA statutory terms cited above are included in the
relevant sections below.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for 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 19, 2021, NMFS received a request from the ADOT for an
IHA to take marine mammals incidental to the construction of two ferry
berth facilities in Tongass Narrows in Ketchikan, Alaska: The Gravina
Airport Ferry Layup Facility and the Gravina Freight Facility. On
December 17, 2021 we received a revised request that included
additional work components associated with the Revilla New Ferry Berth
and Upland Improvements and the New Gravina Island Shuttle Ferry Berth
and Related Terminal Improvements in the same region. The application
was deemed adequate and complete on January 4, 2022. ADOT's request is
for take of a small number of eight species of marine mammals, by Level
B harassment and Level A harassment. Of those eight species, five
(Steller sea lion (Eumetopias jubatus), harbor seal (Phoca vitulina
richardii), harbor porpoise (Phocoena phocoena), Dall's porpoise
(Phocoenoides dalli) and minke whale (Balaenoptera acutorostrata)) may
also be taken by Level A harassment. Neither the ADOT nor NMFS expects
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
NMFS previously issued two consecutive IHAs and a Renewal IHA to
ADOT for this work (85 FR 673, January 7, 2020; 86 FR 23938, May 05,
2021).
[[Page 5981]]
ADOT complied with all the requirements (e.g., mitigation, monitoring,
and reporting) of the previous IHAs and information regarding their
monitoring results may be found in the Description of Marine Mammals in
the Area of Specified Activities and Marine Mammal Occurrence and Take
Calculation and Estimation sections. An IHA for the first phase of
construction of the Ketchikan-Gravina Access Project was issued to ADOT
on December 20, 2019 (85 FR 673, January 7, 2020). Complete
construction of two of those components, the Revilla New Ferry Berth
and Upland Improvements and Gravina Island Shuttle Ferry Berth
Facility/Related Terminal Improvements, did not occur within the
timeframe authorized by the Phase 1 IHA and will not be finished before
the expiration of the subsequent one-year renewal (86 FR 23938, May 05,
2021). Therefore, ADOT is requesting a new IHA for incidental take
associated with the continued marine construction of these facilities.
This proposed IHA would be valid for one year.
Description of Proposed Activity
Overview
ADOT is making improvements to existing ferry berths and
constructing new ferry berths on Gravina Island and Revillagigedo
(Revilla) Island in Tongass Narrows, near Ketchikan in southeast Alaska
(Figure 1). These ferry facilities provide the only public access
between the city of Ketchikan, AK on Revilla Island, and the Ketchikan
International Airport on Gravina Island (Figure 1). The project's
proposed activities that have the potential to take marine mammals, by
Level A harassment and Level B harassment, include vibratory and impact
pile driving, down-the-hole (DTH) operations for pile installation
(rock socketing of piles and tension anchors to secure piles), and
vibratory pile removal. The marine construction associated with the
proposed activities is planned to occur over 91 non-consecutive days
over one year beginning March 2022.
Improvement and construction of facilities is important to provide
reliable access to the airport and facilitate growth and development in
the region. Some of the existing ferry facilities are aging and
periodically out-of-service for repairs or maintenance, and this
project would provide redundant ferry berths to increase reliability.
Ketchikan is Alaska's fifth largest city, with a population of
approximately 8,125 (DCCED 2017), and has numerous marine facilities
including fishing infrastructure, cruise and ferry terminals, and
shipyards.
BILLING CODE 3510-22-P
[[Page 5982]]
[GRAPHIC] [TIFF OMITTED] TN02FE22.000
BILLING CODE 3510-22-C
Dates and Duration
In-water construction is scheduled to begin on March 1, 2022, upon
expiration of the current Phase I IHA (86 FR 23938; May 5, 2021). ADOT
anticipates that construction would occur during daylight hours only
with in-water construction occurring 6 days per week. ADOT anticipates
that the project would require approximately 91 days of pile
installation and removal
[[Page 5983]]
over the course of 7 or 8 months. Although it is anticipated that the
project would be completed sooner, ADOT requests that the IHA be valid
for a full year, from March 1, 2022 to February 28, 2023, to
accommodate scheduling unknowns or delays.
ADOT plans to implement the Essential Fish Habitat (EFH)
Conservation Recommendations developed by NMFS. No in-water work would
occur between March 1 and June 15 for three project components: The
Revilla New Ferry Berth and Upland Improvements, Gravina Airport Ferry
Layup Facility, and Revilla Refurbish Existing Ferry Berth Facility.
Specific Geographic Region
The proposed construction project is located in Ketchikan, Alaska
(Figure 1). Improvements to the Gravina Airport Ferry Layup Facility
construction would occur in the same location as the existing layup
dock facility. The new Gravina Freight Facility would be constructed in
the same location as the existing barge offload facility. The New
Gravina Island Shuttle Ferry Berth construction would occur slightly
North of the Airport Ferry Layup Facility. Improvements and
construction on Revilla Island would occur approximately 4 kilometers
(km; 2.5 miles (mi)) north of downtown Ketchikan. The new Revilla
Island Airport Shuttle Ferry Berth would be constructed immediately
adjacent to the existing Revilla Island Ferry Berth.
Tongass Narrows is an approximately 13-mile-long, north-south-
oriented marine channel situated between Revilla Island to the east and
Gravina Island to the west. In the vicinity of the proposed project,
Tongass Narrows is as little as 300 meters (m; 984 feet; ft) wide.
Tongass Narrows is generally characterized by strong tidal currents and
by steep bedrock or coarse gravel-cobble-boulder shoreline. Lower
intertidal and shallow subtidal areas are often sandy or mixed gravel,
sand, and shell, with varied amounts of silt. At other areas, however,
such as at rocky points and along the northwestern shore of Pennock
Island (which is located in the south end of Tongass Narrows, between
Gravina and Revilla Islands), bedrock slopes steeply to subtidal
depths. Subtidal habitats are a mix of bedrock outcrops or ledges,
boulder-cobble slopes, and, where lower slopes permit, sandy gravel
bottoms, often mixed with significant amounts of shell debris, similar
to intertidal habitats.
Several small natural coves and areas protected by constructed
breakwaters provide wave and current protection for marine habitats
with sand or gravel bottoms with some areas of eelgrass (Zostera
marina) beds. Extensive areas of riprap bank protection and fill occur
along the northeastern shoreline of the City of Ketchikan. Construction
of numerous buildings and docks on pilings over the intertidal and
shallow subtidal zone has significantly modified the shorelines in
these areas. Shoreline protection activities have similarly modified
approximately 1 mile of the shoreline of Gravina Island in the vicinity
of the airport and airport ferry terminal.
Water depths reach approximately 49 m (160 ft) in the middle of the
Tongass Narrows between the airport and town, but generally do not
exceed 18 m (60 ft) where piles would be installed. The channel bottom
slopes at about 2:1 (horizontal: vertical) from opposite shores.
Geological conditions in the vicinity of the project were recently
evaluated (CH2M 2018). The substrate consists of approximately 18 to 23
m (60 to 75 ft) of very loose to very dense granular deltaic or
alluvial sand and gravel. At approximately 18 to 23 m (60 to 75 ft)
below the mudline, the substrate transitions to phyllite bedrock (CH2M
2018). Pile installation would occur in waters ranging in depth from
less than 1 m (3.3 ft) nearshore to approximately 20 m (66 ft),
depending on the structure and location.
Ongoing vessel activities throughout Tongass Narrows, land-based
industrial and commercial activities, and regular aircraft operations
result in elevated in-air and underwater sound conditions in the
project area that increase with proximity to the proposed project
component sites. Sound levels likely vary seasonally, with elevated
levels during summer when the tourism and fishing industries are at
their peaks.
Detailed Description of Specific Activity
Planned construction includes the installation and continued
construction of new ferry facilities and the renovation of existing
structures. As stated above, the four proposed construction components
include: The Gravina Airport Ferry Layup Facility, the Gravina Freight
Facility, the Revilla New Ferry Berth and Upland Improvements, and the
New Gravina Island Shuttle Ferry Berth and Related Terminal
Improvements. ADOT anticipates that work may occur at multiple sites
concurrently, and that two hammers or DTH equipment could be used
concurrently (discussed further in the Estimated Take section).
Gravina Airport Ferry Layup Facility
The new ferry layup dock and transfer bridge would support layup
and maintenance of the airport ferry system. The current layup dock at
the Gravina Airport Ferry Layup Facility is in disrepair and needs to
be replaced. ADOT would remove the existing 265-ft (80.1-m)-long
floating dock, mooring structures, and transfer bridge and construct a
new 250-ft by 85-ft (76.2 m by 25.9 m) concrete or steel floating dock
in its place. The floating dock would be restrained by two side-
restraint float dolphins and three corner/mid-restraint float dolphins.
A new 20-ft by 140-ft (6.1 m by 42.6 m) steel transfer bridge would
provide access to the floating dock. It would be necessary to remove,
relocate, and replenish the existing rock slope, demolish the existing
concrete abutment, and construct a new pile-supported bridge abutment.
The Gravina Airport Ferry Layup Facility construction and Gravina
Freight Facility construction is anticipated to require a total of 47
days of in-water pile installation and removal.
Gravina Freight Facility
The new Gravina Freight Facility, located approximately 100 m from
the Gravina Airport Ferry Layup Facility (Figure 1), would be
constructed in the same location as the existing barge offload
facility. This facility would provide improved access to Gravina Island
for highway loads that cannot be accommodated by the shuttle ferry. The
existing ramp would be widened and re-graded both above and below the
high tide line. A new concrete plank or asphalt pavement ramp would be
constructed in its place. Five breasting dolphins and one mooring
dolphin would be constructed to support barge docking and would include
pedestrian walkways for access by personnel. In addition, two new pile-
supported mooring structures would be constructed above the high tide
line. As stated above, the Gravina Airport Ferry Layup Facility
construction and Gravina Freight Facility construction is anticipated
to require a total of 47 days of in-water pile installation and
removal.
Revilla New Ferry Berth and Upland Improvements
The new Revilla Island airport shuttle ferry berth is the only
project component that would occur on Revilla Island, and is currently
under construction immediately adjacent to the existing Revilla Island
Ferry Berth (Figure 1). The new ferry berth consists of a 7,400 square
ft (ft\2\; 687.4 m\2\) pile-supported approach trestle at the shore
side of the ferry terminal and a 1,500 ft\2\ (139.4 m) pile-supported
approach
[[Page 5984]]
trestle extension located landside and north of the new approach
trestle. A 25-ft by 142-ft (7.6 m by 43.2 m) steel transfer bridge with
vehicle traffic lane and separated pedestrian walkway extends from the
trestle to a new 2,200 ft\2\ (204.3 m\2\) steel float and apron. The
steel float is supported by three guide pile dolphins. A bulkhead
retaining wall is being constructed at the transition from uplands to
the approach trestle. Two new stern berth dolphins with fixed hanging
fenders and three new floating fender dolphins are being constructed to
moor vessels. The new apron would be supported by three new guide pile
dolphins. Water depths at the dolphins reach approximately 60 ft (18.2
m).
While construction on the Revilla New Ferry Berth is already
underway, ADOT anticipates that it would not be complete before ADOT's
current IHA (86 FR 23938; May 5, 2021) expires. Therefore, ADOT has
requested take associated with the portion of the project that it
anticipates may remain, which consists of installation of up to five
tension anchors.
Upland improvements associated with the Revilla New Ferry Berth
include reconstruction of terminal facilities, installation of
utilities, and construction of improvements to existing staging/parking
areas. Upland improvements are not anticipated to harass marine
mammals, and therefore, are not discussed further in this document.
Gravina Island Shuttle Ferry Berth and Related Terminal Improvements
The new Gravina Island Airport Shuttle Ferry Berth is currently
under construction (86 FR 23938; May 5, 2021) immediately adjacent to
the existing Gravina Island Ferry Berth (Figure 1). The new facility
consists of an approximately 7,000 ft\2\ (650.3 m\2\) pile-supported
approach trestle at the shore side of the ferry terminal. A 25-ft by
142-ft (7.6 m by 43.2 m) steel transfer bridge with vehicle traffic
lane and separated pedestrian walkway leads to a new 2,200 ft\2\ (204.3
m\2\) steel float and apron. The steel float is supported by three new
guide pile dolphins. Ferry berthing is supported by two new stern berth
dolphins and three new floating fender dolphins. To support the new
facility, a new bulkhead retaining wall is being constructed between
the existing ferry berth and the new approach trestle. A new fill slope
measuring approximately 21,200 ft\2\ (1,969.5 m\2\) is being
constructed west of the approach trestle. Upland improvements include
widening of the ferry approach road, retrofits to the existing
pedestrian walkway, installation of utilities, and construction of a
new employee access walkway. Due to unforeseen construction delays
encountered during the Phase 1 IHA construction period, ADOT
anticipates that construction on the Gravina Island Shuttle Ferry Berth
would not be completed before the expiration of the current IHA (86 FR
23938; May 5, 2021). Therefore, ADOT has requested take associated with
the portion of the project that it anticipates may remain, which
consists of up to 35 piles (both plumb and battered), 17-21 rock
sockets, 28 tension anchors, and up to 4 micropile anchors (Table 1).
Across the four project sites, three methods of pile installation
are anticipated. These include vibratory and impact hammers, use of DTH
systems to make holes for rock sockets and tension and micropile
anchors at some locations (Figure 1-3 of ADOT's IHA Application).
Installation of steel piles through the sediment layer would be
accomplished using vibratory or impact methods. Depending on the
location, the pile would be advanced to refusal at bedrock. Where
sediments are deep and rock socketing or anchoring (described below) is
not required, the final approximately 10 ft (3 m) of driving would be
conducted using an impact hammer so that the structural capacity of the
pile embedment can be verified or proofed. Proofing is expected to
require approximately 50 strikes over 15 minutes. Where sediments are
shallow, an impact hammer would be used to seat the piles into
competent bedrock before a DTH system is used to create holes for the
rock sockets and/or tension anchors. The pile installation methods used
would depend on sediment depth and conditions at each pile location.
Rock sockets are holes made in the bedrock where overlying
sediments are too shallow to adequately secure the bottom portion of a
pile using other methods. Rock sockets are constructed utilizing a DTH
device which uses both rotary and percussion-type drill action. These
devices consist 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, creating a hole that allows for
insertion of the pile. The socket holes are just large enough for the
pile to fit down in to provide lateral strength for the pile. The pile
is usually advanced at the same time that drilling occurs (the bit has
a flexible tip that can be retracted and pulled back up through the
center of a pile). Rock socket holes would be up to 15 ft (4.6 m) into
the bedrock. Drill cuttings are expelled from the top of the pile using
compressed air and/or other fluids. It is estimated that use of DTH for
rock sockets into the bedrock would take approximately 4-8 hours per
pile. Some piles would be seated in rock sockets as well as anchored
with tension anchors.
Tension anchors are comprised of a threaded steel rod grouted into
the bedrock strata at a specified depth below the pile tip. The rod is
tested and anchored to the top of the pile to resist uplift forces in
the associated structure. Tension anchors are installed within piles
that are DTH drilled or hammered 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-inch-diameter steel pipe casing is inserted
inside the larger-diameter production pile. A DTH hammer and bit is
inserted into the casing, and a 6- to 8-inch-diameter hole is made into
bedrock. The typical depth of the hole varies, but 20-30 ft (6.1-9.1 m)
is common to meet engineering needs. Rock fragments would be removed
through the top of the casing with compressed air. A steel rebar rod is
then grouted into the drilled hole and affixed to the top of the pile.
Micropiles have a casing diameter of approximately 3 to 10 in. A
DTH hammer device is used to create a hole in a manner identical to the
rock sockets as described above. The micropile casing is inserted to
depth and a steel reinforcement bar is inserted in the casing, and then
grout is pumped into the casing. The construction of the Gravina Island
Shuttle Ferry Berth could potentially utilize up to four micropiles.
Because both tension anchors and micropiles require drilling an 8-inch-
diameter hole, they are discussed together throughout this document.
Vibratory methods would also be used to remove temporary steel pipe
piles. These proposed activities and the noise they produce have the
potential to take marine mammals, by Level A harassment and Level B
harassment of marine mammals.
Each of the project components would include installation of steel
pipe piles that are 20, 24, or 30 inches in diameter (Table 1).
Temporary piles would be installed and removed with a vibratory hammer.
Some permanent piles would be battered (i.e., installed at an angle).
Approximately 50 impact strikes would be required for proofing each
permanent pile, requiring approximately 15 minutes of active impact
hammering per pile.
The estimated average installation rate for the project is one to
one and a half permanent or two temporary pipe piles per day (Table 1).
On some days,
[[Page 5985]]
more or fewer piles or partial piles may be installed. It would likely
not be possible to install an individual permanent pile to refusal with
a vibratory hammer, use DTH methods for the rock socket, impact proof,
and install the tension anchor on the same day. The construction crew
may use a single installation method for multiple piles on a single day
or find other efficiencies to increase production; the anticipated
ranges of possible values are provided in Table 1. The estimated
removal rate for temporary piles is two steel pipe piles per day. On
some days, more or fewer piles may be removed. It is estimated that the
40 temporary piles would be removed in 36 days.
In sum, approximately 91 days of pile installation and removal are
anticipated (Table 1), and of the 102 piles which ADOT anticipates it
will install, 40 of them will be installed and removed (for a total of
142 pile installations and removals).
Above-water work would consist of the installation of a concrete
float, a transfer bridge and transition ramp, dock-mounted fenders, and
utility lines. A utility and storage building would be constructed on
top of the concrete float. No in-water noise is anticipated in
association with above-water and upland construction activities, and no
associated take of marine mammals is anticipated from the noise or
visual disturbance. Therefore, above-water and upland construction
activities are not discussed further in this document.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN02FE22.001
[[Page 5986]]
BILLING CODE 3510-22-C
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's Stock Assessment Reports (SARs; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</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 specified activity, and summarizes
information related to the population or stock, including regulatory
status under the MMPA and Endangered Species Act (ESA) and potential
biological removal (PBR), where known. For taxonomy, we follow
Committee on Taxonomy (2021). 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's
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's 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's U.S. Alaska SARs (e.g., Muto et al. 2021). All values presented
in Table 2 are the most recent available at the time of publication and
are available in the draft 2021 SARs (Muto et al. 2021; available
online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>).
Table 2--Marine Mammal Species or Stocks for Which Take Is Expected and Proposed To Be Authorized
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stock abundance
ESA/MMPA status; Nbest, (CV; Nmin; Annual M/
Common name Scientific name MMPA stock strategic (Y/N) most recent abundance PBR SI \3\
\1\ survey) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
Humpback whale................. Megaptera novaeangliae Central North Pacific E, D, Y 10,103 (0.3; 7,890; 83.............. 26
2006).
Minke whale.................... Balaenoptera Alaska............... -, N N.A.(See SAR; N.A.; UND............. 0
acutorostrata. see SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Killer whale................... Orcinus orca.......... Alaska Resident...... -, N 2,347 (N.A.; 2,347; 24.............. 1
2012).
West Coast Transient. -, N 349 (N.A, 349; 2018). 3.5............. 0.4
Northern Resident.... -, N 302 (N.A.; 302; 2018. 2.2............. 0.2
Pacific white-sided dolphin.... Lagenorhynchus North Pacific........ -,-; N 26,880 (N.A.; N.A.; UND............. 0
obliquidens. 1990).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor porpoise................ Phocoena phocoena..... Southeast Alaska..... -, Y See SAR (see SAR; see See SAR......... 34
SAR; 2012).
Dall's porpoise................ Phocoenoides dalli.... Alaska............... -, N See SAR (see SAR; see See SAR......... 37
SAR; 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Steller sea lion............... Eumetopias jubatus.... Eastern U.S.......... -,-, N 43,201 (see SAR; 2,592........... 112
43,201; 2017).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor seal.................... Phoca vitulina Clarence Strait...... -, N 27,659 (See SAE; 746............. 40
richardii. 24,854; 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a> assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury (M/SI) 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.
All species that could potentially occur in the proposed survey
areas are included in Table 3-1 of the IHA application. However, the
spatial occurrence of gray whale and fin whale is such that take is not
expected to
[[Page 5987]]
occur, and they are not discussed further beyond the explanation
provided here. Gray whales have not been reported by any local experts
or recorded in monitoring reports and it would be extremely unlikely
for a gray whale to enter Tongass Narrows or the small portions of
Revillagigedo Channel this project would impact. Similarly for fin
whale, sightings have not been reported and it would be unlikely for a
fin whale to enter the project area as they are generally associated
with deeper, more offshore waters. The remaining 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.
Humpback Whale
Humpback whales are found throughout Southeast Alaska in a variety
of marine environments, including open-ocean, near-shore waters, and
areas with strong tidal currents (Dahlheim et al. 2009). Most humpback
whales are migratory and spend winters in the breeding grounds off
either Hawaii or Mexico. Humpback whales generally arrive in Southeast
Alaska in March and return to their wintering grounds in November. Some
humpback whales depart late or arrive early to feeding grounds, and
therefore the species occurs in Southeast Alaska year-round (Straley
1990; Straley et al. 2018). Current threats to humpback whales include
vessel strikes, spills, climate change, and commercial fishing
operations (Muto et al. 2021).
Humpback whales worldwide were designated as ``endangered'' under
the Endangered Species Conservation Act in 1970, and were listed under
the ESA at its inception in 1973. However, on September 8, 2016, NMFS
published a final decision that changed the status of humpback whales
under the ESA (81 FR 62259), effective October 11, 2016. The decision
recognized the existence of 14 DPSs based on distinct breeding areas in
tropical and temperate waters. Five of the 14 DPSs were classified
under the ESA (4 endangered and 1 threatened), while the other 9 DPSs
were delisted. Humpback whales found in the project area are
predominantly members of the Hawaii DPS, which is not listed under the
ESA. However, based on a comprehensive photo-identification study,
members of the Mexico DPS, which is listed as threatened, are known to
occur in Southeast Alaska. Members of different DPSs are known to
intermix on feeding grounds; therefore, all waters off the coast of
Alaska should be considered to have ESA-listed humpback whales.
Approximately 2 percent of all humpback whales in Southeast Alaska and
northern British Columbia are members of the Mexico DPS, while all
others are members of the Hawaii DPS (Wade et al. 2021).
The DPSs of humpback whales that were identified through the ESA
listing process do not necessarily equate to the existing MMPA stocks.
The stock delineations of humpback whales under the MMPA are currently
under review. Until this review is complete, NMFS considers humpback
whales in Southeast Alaska to be part of the Central North Pacific
stock, with a status of endangered under the ESA and designations of
strategic and depleted under the MMPA (Muto et al. 2021).
Southeast Alaska is considered a biologically important area for
feeding humpback whales between March and May (Ellison et al. 2012),
though not currently designated as critical habitat (86 FR 21082; April
21, 2021). Most humpback whales migrate to other regions during the
winter to breed, but rare events of over-wintering humpbacks have been
noted, and may be attributable to staggered migration (Straley, 1990;
Straley et al. 2018). It is thought that those humpbacks that remain in
Southeast Alaska do so in response to the availability of winter
schools of fish prey, which primarily includes overwintering herring
(Straley et al. 2018). In Alaska, humpback whales filter feed on tiny
crustaceans, plankton, and small fish such as walleye pollock, Pacific
sand lance, herring, eulachon, and capelin (Witteveen et al. 2012). It
is common to observe groups of humpback whales cooperatively bubble
feeding. Group sizes in Southeast Alaska generally range from one to
four individuals (Dahlheim et al. 2009).
No systematic studies have documented humpback whale abundance near
Ketchikan. Anecdotal information (See Section 4 of IHA Application)
suggests that this species is present in low numbers year-round in
Tongass Narrows, with the highest abundance during summer and fall.
Anecdotal reports suggest that humpback whales are seen only once or
twice per month, while more recently it has been suggested that the
occurrence is more regular, such as once per week on average, and more
seasonal. Humpbacks observed in Tongass Narrows are generally alone or
in groups of one to three individuals. Most humpback whales depart
Alaska for their breeding grounds in October and November, and return
in March and April. In August 2017, a group of six individuals was
observed passing through Tongass Narrows several times per day, for
several days in a row. Local residents reported that such high
abundance is common in August and September. NMFS reported that in 2018
airport ferry personnel observed a lone humpback whale in the area
every few days for several months and a group of two humpback whales
every other week (Muto et al. 2019).
In the Biological Opinion for this project, NMFS assumed the
occurrence of humpback whales in the project area to be one two
individuals twice per week, year-round. The assumption was based on
differences in abundance throughout the year, recent observations of
larger groups of whales present during summer, and a higher than
average frequency of occurrence in recent months.
The City of Ketchikan (COK) Rock Pinnacle project, which was
located approximately 4 km southeast of the proposed project site,
reported one humpback whale sighting of one individual during the
project (December 2019 through January 2020) (Sitkiewicz 2020). During
the Ward Cove Cruise Ship Dock Construction, located approximately 5 km
northwest of the proposed project site, protected species observers
(PSOs) observed 28 sightings of humpbacks on eighteen days of in water
work that occurred between February and September 2020, with at least
one humpback being recorded every month. A total of 42 individuals were
recorded and group sizes ranged from solo whales to pods of up to six
(Power Systems & Supplies of Alaska 2020). Humpbacks were recorded in
each month of construction, with the most individuals (10) being
recorded in May, 2020.
Humpback whales were sighted on 17 days out of 88 days of
monitoring in Tongass Narrows in 2020 and 2021 (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). There were no sightings in January or February,
but humpback whales were observed each month from October to December
2020 and May to June 2021 (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
There was only 1 day in June in which humpback whales were observed,
but on that day there were four groups of whales--three pairs and one
group of four (DOT&PF 2021d). In other months, humpback whale sightings
were mostly individual animals and occasionally pairs. During November
2020, a single known individual (by fluke pattern) was observed
repeatedly, accounting for 14 of the 26 sighting events that month
(DOT&PF 2020). During monitoring, humpback whales were observed on
average once a week.
[[Page 5988]]
Minke Whale
Minke whales are found throughout the northern hemisphere in polar,
temperate, and tropical waters. The population status of minke whales
is considered stable throughout most of their range. Historically,
commercial whaling reduced the population size of this species, but
given their small size, they were never a primary target of whaling and
did not experience the severe population declines as did larger
cetaceans.
The International Whaling Commission has identified a less
concentrated stock throughout the eastern Pacific. NOAA further splits
this stock between Alaska whales and resident whales of California,
Oregon, and Washington (Muto et al., 2021). Minke whales are found in
all Alaska waters. There are no population estimates for minke whales
in Alaska. Surveys in Southeast Alaska have consistently identified
individuals throughout inland waters in low numbers (Dahlheim et al.
2009).
Minke whales in Southeast Alaska are part of the Alaska stock (Muto
et al. 2021). 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, with small concentrations near
the entrance of Glacier Bay (Dahlheim et al. 2009). All sightings were
of single minke whales, except for a single sighting of multiple minke
whales. Surveys took place in spring, summer, and fall, and minke
whales were present in low numbers in all seasons and years. No
information appears to be available on the winter occurrence of minke
whales in Southeast Alaska.
In Alaska, the minke whale diet consists primarily of euphausiids
and walleye pollock. Minke whales are generally found in shallow,
coastal waters within 200 m of shore (Zerbini et al. 2006) and are
almost always solitary or in small groups of 2 to 3. In Alaska,
seasonal movements are associated with feeding areas that are generally
located at the edge of the pack ice (NMFS 2014).
There are no known occurrences of minke whales within the project
area. Since their ranges extend into the project area and they have
been observed in southeast Alaska, including in Clarence Strait
(Dahlheim et al., 2009), it is possible the species could occur near
the project area. During the surveys by Dalheim et al. (2009), all but
one encounter was with a single whale and, although infrequent, minke
whales were observed during all seasons surveyed (spring, summer and
fall). No minke whales where reported during the COK Rock Pinnacle
Blasting Project (Sitkiewicz 2020). During marine mammal monitoring of
Tongass Narrows in 2020 and 2021, there were no minke whales observed
on 88 days of observations across 7 months (October 2020-February 2021;
May-June 2021) (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). Future
observations of minke whale in the project area are expected to be
rare.
Killer Whale
Killer whales have been observed in all the world's oceans, but the
highest densities occur in colder and more productive waters found at
high latitudes (NMFS 2016). Killer whales occur along the entire Alaska
coast, in British Columbia and Washington inland waterways, and along
the outer coasts of Washington, Oregon, and California (NMFS 2016).
Based on data regarding association patterns, acoustics, movements,
and genetic differences, eight killer whale stocks are now recognized
within the Pacific U.S. Exclusive Economic Zone. This proposed IHA
considers only the Eastern North Pacific Alaska Resident stock (Alaska
Resident stock), Eastern North Pacific Northern Resident stock
(Northern Resident stock), and West Coast Transient stock, because all
other stocks occur outside the geographic area under consideration
(Muto et al., 2021).
There are three distinct ecotypes, or forms, of killer whales
recognized: Resident, Transient, and Offshore. The three ecotypes
differ morphologically, ecologically, behaviorally, and genetically.
Surveys between 1991 and 2007 encountered resident killer whales during
all seasons throughout Southeast Alaska. Both residents and transients
were common in a variety of habitats and all major waterways, including
protected bays and inlets. There does not appear to be strong seasonal
variation in abundance or distribution of killer whales, but there was
substantial variability between years during this study (Dahlheim et
al., 2009). Spatial distribution has been shown to vary among the
different ecotypes, with resident and, to a lesser extent, transient
killer whales more commonly observed along the continental shelf, and
offshore killer whales more commonly observed in pelagic waters (Rice
et al., 2021).
No systematic studies of killer whales have been conducted in or
around Tongass Narrows. Killer whales have been observed in Tongass
Narrows year-round and are most common during the summer Chinook salmon
run (May-July). During the Chinook salmon run, Ketchikan residents have
reported pods of 20-30 whales and during the 2016/2017 winter a pod of
5 whales was observed in Tongass Narrows (84 FR 36891; July 30, 2019).
Typical pod sizes observed within the project vicinity range from 1 to
10 animals and the frequency of killer whales passing through the
action area is estimated to be once per month (Frietag 2017). Anecdotal
reports suggest that large pods of killer whales (as many as 80
individuals, but generally between 25 and 40 individuals) are not
uncommon in May, June, and July when the king salmon are running.
During the rest of the year, killer whales occur irregularly in pods of
6 to 12 or more individuals. Large pods would be indicative of the
Alaska resident population, which travels and hunts in large social
groups.
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 6.0 in spring, 5.0 in summer, and 3.9 in fall. Pod sizes of
transient whales are generally smaller than those of resident social
groups. Resident killer whales occur in larger 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).
Although killer whales may occur in large numbers, they generally
form large pods and would incur fewer work stoppages than their numbers
suggest. Killer whales tend to transit through Tongass Narrows, and do
not linger in the project area.
Marine mammal observations in Tongass Narrows during 2020 and 2021
support an estimate of approximately one group of killer whales a month
in the project area. During 7 months of monitoring (October 2020-
February 2021; May-June 2021), there were five killer whale sightings
in 4 months (November, February, May, June) totaling 22 animals and
sightings occurred on 5 out of 88 days of monitoring (DOT&PF 2020,
2021a, 2021b, 2021c, 2021d). Pod sizes ranged from two to eight animals
(DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). During the COK's monitoring
for the Rock Pinnacle Removal project in December 2019 and January
2020, no killer whales were observed (Sitkiewicz 2020). Over 8 months
of monitoring at the Ward Cove Cruise Ship Dock in 2020, killer whales
were only observed on two days in March (Power Systems
[[Page 5989]]
and Supplies of Alaska, 2020). These observations included a sighting
of one pod of two killer whales and a second pod of five individuals
travelling through the project area.
Pacific White-Sided Dolphin
Pacific white-sided dolphins are a pelagic species inhabiting
temperate waters of the North Pacific Ocean and along the coasts of
California, Oregon, Washington, and Alaska (Muto et al., 2021). Despite
their distribution mostly in deep, offshore waters, they may also be
found over the continental shelf and near shore waters, including
inland waters of Southeast Alaska (Ferrero and Walker 1996). The North
Pacific stock is found within the project area. The Pacific white-sided
dolphin is distributed throughout the temperate North Pacific Ocean,
north of Baja California to Alaska's southern coastline and Aleutian
Islands. The North Pacific Stock ranges from Canada into Alaska (Muto
et al., 2021).
Pacific white-sided dolphins prey on squid and small schooling fish
such as capelin, sardines, and herring (Morton 2006). They are known to
work in groups to herd schools of fish and can dive underwater for up
to 6 minutes to feed (Morton 2006). Group sizes have been reported to
range from 40 to over 1,000 animals, but groups of between 10 and 100
individuals (Stacey and Baird 1991) occur most commonly. Seasonal
movements of Pacific white-sided dolphins are not well understood, but
there is evidence of both north-south seasonal movement (Leatherwood et
al. 1984) and inshore-offshore seasonal movement (Stacey and Baird
1991).
Scientific studies and data are lacking relative to the presence or
abundance of Pacific white-sided dolphins in or near Tongass Narrows.
Although they generally prefer deeper and more-offshore waters,
anecdotal reports suggest that Pacific white-sided dolphins have
previously been observed in Tongass Narrows, although they have not
been observed entering Tongass Narrows or nearby inter-island waterways
in 15-20 years.
Pacific white-sided dolphins are rare in the inside passageways of
Southeast Alaska. Most observations 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 Tongass Narrows.
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. Dalheim et al. (2009) frequently
encountered Pacific white-sided dolphin in Clarence Strait with
significant differences in mean group size and rare enough encounters
to limit the seasonality investigation to a qualitative note that
spring featured the highest number of animals observed. These
observations were noted most typically in open strait environments,
near the open ocean. Mean group size was over 20, with no recorded
winter observations nor observations made in the Nichols Passage or
Behm Canal, located on either side of the Tongass Narrows. Though
generally preferring more pelagic, open-water environments, Pacific
white-sided dolphin could be present within the action area during the
construction period. This observational data, combined with anecdotal
information, indicates there is a rare, however, slight potential for
Pacific white-sided dolphins to occur in the project area.
During marine mammal monitoring of Tongass Narrows in 2020 and
2021, no Pacific white-sided dolphins were observed on 88 days of
observations across 7 months (October 2020-February 2021; May-June
2021), which supports the anecdotal evidence that sightings of this
species are rare (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). There were
also no sightings of Pacific white-sided dolphins during the COK Rock
Pinnacle Blasting Project during monitoring surveys conducted in
December 2019 and January 2020 (Sitkiewicz 2020) or during monitoring
surveys conducted between February and September 2020 as part of the
Ward Cove Cruise Ship Dock (Power Systems and Supplies of Alaska,
2020).
Harbor Porpoise
In the eastern North Pacific Ocean, the harbor porpoise ranges from
Point Barrow, along the Alaska coast, and down the west coast of North
America to Point Conception, California. In Alaska, harbor porpoises
are currently divided into three stocks, based primarily on geography:
The Bering Sea stock, the Southeast Alaska stock, and the Gulf of
Alaska stock. The Southeast Alaska stock ranges from Cape Suckling to
the Canadian border (Muto et al. 2021). Harbor porpoises frequent
primarily coastal waters in Southeast Alaska (Dahlheim et al. 2009) and
occur most frequently in waters less than 100 m (328 ft) deep (Hobbs
and Waite 2010; Dahlheim et al. 2015).
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). The project area and Tongass Narrows fall
within the Clarence Strait to Ketchikan region, as identified by this
study for the survey effort. Harbor porpoise densities in this region
in summer were low, ranging from 0.01 to 0.02 harbor porpoises/km\2\.
Studies of harbor porpoises reported no evidence of seasonal
changes in distribution for the inland waters of Southeast Alaska
(Dahlheim et al. 2009). Their small overall size, lack of a visible
blow, low dorsal fins and overall low profile, and short surfacing time
make them difficult to observe (Dahlheim et al. 2015), likely reducing
identification and reporting of this species, and these estimates
therefore may be low.
Calving occurs from May to August; however, this can vary by
region. Harbor porpoises are often found traveling alone, or in small
groups less than 10 individuals (Schmale 2008). According to aerial
surveys of harbor porpoise abundance in Alaska conducted in 1991-1993,
mean group size in Southeast Alaska was calculated to be 1.2 animals
(Dahlheim et al. 2000).
Anecdotal reports (see Section 3 of the IHA Application) specific
to Tongass Narrows indicate that harbor porpoises are rarely observed
in the project area, and actual sightings are less common than those
suggested by Dahlheim et al. (2015). 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 Tongass
Narrows. Harbor porpoises are expected to be present in the project
area only a few times per year. Freitag (2017 as cited in 83 FR 22009;
May 11, 2018) observed harbor porpoises in Tongass Narrows zero to one
time per month and NMFS (83 FR 22009; May 11, 2018) has estimated that
one group of harbor porpoises would enter Tongass Narrows each month.
Harbor porpoises were sighted on 3 days of in-water work during
monitoring associated with the Ward Cove Cruise Ship Dock, with three
sightings of 15 individuals sighted in March and April, 2020 (Power
Systems and Supplies of Alaska, 2020). Solo individuals and pods of up
to 10 were identified as swimming and travelling 2,500 m to 2,800 m
from in-water work. During marine mammal monitoring of Tongass Narrows
in 2020 and 2021, no harbor porpoises were observed on 88 days of
observations across 7 months (October 2020-February 2021; May-June
2021), which supports the anecdotal evidence that harbor porpoise
sightings are rare (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). Marine
mammal
[[Page 5990]]
monitoring associated with the COK Rock Pinnacle Removal project also
did not observe any harbor porpoise during surveys conducted in
December 2019 and January 2020 (Sitkiewicz 2020).
Dall's Porpoise
Dall's porpoises are found throughout the North Pacific, from
southern Japan to southern California north to the Bering Sea. Dall's
porpoises are not listed as endangered or threatened under the ESA. All
Dall's porpoises in Alaska are members of the Alaska stock, and those
off California, Oregon, and Washington are part of a separate stock.
This species can be found in offshore, inshore, and nearshore habitat,
but prefer waters more than 600 ft (180 m) deep (Jefferson 2009).
No systematic studies of Dall's porpoise abundance or distribution
have occurred in Tongass Narrows; however, surveys for cetaceans
throughout Southeast Alaska were conducted between 1991 and 2007
(Dahlheim et al. 2009). The species is generally found in waters in
excess of 600 ft (183 m) deep (Dahlheim et al. 2009, Jefferson 2009),
which do not occur in Tongass Narrows. Jefferson et al. (2019) presents
historical survey data showing few sightings in the Ketchikan area, and
based on these occurrence patterns, concludes that Dall's porpoise
rarely come into narrow waterways, like Tongass Narrows. Anecdotal
reports suggest that Dall's porpoises are found northwest of Ketchikan
near the Guard Islands, where waters are deeper, as well as in deeper
waters to the southeast of Tongass Narrows. Should Dall's porpoises
occur in the project area, they would likely be present in March or
April, given past observations in the region. Despite generalized water
depth preferences, Dall's porpoises may occur in shallower waters. This
species has a tendency to bow-ride with vessels and may occur in the
project area incidentally a few times per year.
The mean group size in Southeast Alaska is estimated at
approximately three individuals (Dahlheim et al. 2009; Jefferson 2019).
However, in the Ketchikan vicinity, Dall's porpoises are reported to
typically occur in groups of 10-15 animals, with an estimated maximum
group size of 20 animals (Freitag 2017, 83 FR 37473; August 1, 2018).
Dall's porpoises were positively identified on 2 days of in-water
work during monitoring associated with the Ward Cove Cruise Ship Dock
(Power Systems and Supplies of Alaska, 2020). A pod of three and a pod
of five were recorded travelling at least 3,000 m from the construction
site in April and May, respectively. During marine mammal monitoring of
Tongass Narrows in 2020 and 2021, there were sightings of Dall's
porpoises on 2 out of 88 days of observations across 7 months (October
2020-February 2021; May-June 2021)--once in November 2020 and once in
February 2021. The pod sighted in November contained six animals; the
pod observed in February had 10. Based on this recent data, there is no
known pattern to their attendance in the project area, but they do
occur rarely (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
Steller Sea Lion
Steller sea lions were listed as threatened range-wide under the
ESA on November 26, 1990 (55 FR 49204). Steller sea lions were
subsequently partitioned into the western and eastern DPSs (and MMPA
stocks) in 1997 (62 FR 24345; May 5, 1997). The eastern DPS remained
classified as threatened until it was delisted in November 2013. The
current minimum abundance estimate for the eastern DPS of Steller sea
lions is 43,201 individuals (Muto et al. 2021). The western DPS (those
individuals west of 144[deg] W longitude or Cape Suckling, Alaska) was
upgraded to endangered status following separation of the DPSs, and it
remains endangered today. There is regular movement of both DPSs across
this 144[deg] W longitude boundary (Jemison et al. 2013), however, due
to the distance from this DPS boundary, it is likely that only eastern
DPS Steller sea lions are present in the project area. Therefore,
animals potentially affected by the project are assumed to be part of
the eastern DPS.
There are several mapped and regularly monitored long-term Steller
sea lion haulouts surrounding Ketchikan, such as West Rocks (36 miles/
58 km) or Nose Point (37 miles/60 km), but none are known to occur
within Tongass Narrows (Fritz et al. 2015). The nearest known Steller
sea lion haulout is located approximately 20 miles (58 km) west/
northwest of Ketchikan on Grindall Island (Figure 4-1 in application).
Summer counts of adult and juvenile sea lions at this haulout since
2000 have averaged approximately 191 individuals, with a range from 6
in 2009 to 378 in 2008. Only two winter surveys of this haulout have
occurred. In March 1993, a total of 239 individuals were recorded, and
in December 1994, a total of 211 individuals were recorded. No sea lion
pups have been observed at this haulout during surveys. Although this
is a limited and dated sample, it suggests that abundance may be
consistent year-round at the Grindall Island haulout.
No systematic studies of sea lion abundance or distribution have
occurred in Tongass Narrows. Anecdotal reports suggest that Steller sea
lions may be found in Tongass Narrows year-round, with an increase in
abundance from March to early May during the herring spawning season,
and another increase in late summer associated with salmon runs.
Overall sea lion presence in Tongass Narrows tends to be lower in
summer than in winter (FHWA 2017). During summer, Steller sea lions may
aggregate outside the project area, at rookery and haulout sites.
Monitoring during construction of the Ketchikan Ferry Terminal in
summer (July 16 through August 17, 2016) did not record any Steller sea
lions (ADOT&PF 2015); however, monitoring during construction of the
Ward Cove Dock, located approximately 6 km northwest of the Project
site, recorded 181 individual sea lions on 44 days between February and
September 2020 (Power Systems & Supplies of Alaska, 2020). Most
sightings occurred in February (45 sightings of 88 sea lions) and March
(34 sightings of 45 sea lions); the fewest number of sightings were
observed in May (1 sighting of 1 sea lion) (Power Systems & Supplies of
Alaska, 2020). Sightings were of single individuals, pairs, and herds
of up to 10 individuals.
Sea lions are known to transit through Tongass Narrows while
pursuing prey. Steller sea lions are also known to follow fishing
vessels, and may congregate in small numbers at seafood processing
facilities and hatcheries or at the mouths of rivers and creeks
containing hatcheries, where large numbers of salmon congregate in late
summer. Three seafood processing facilities are located east of the
proposed berth location on Revilla Island, and two salmon hatcheries
operated by the Alaska Department of Fish & Game (ADF&G) are located
east of the project area. Steller sea lions may aggregate near the
mouth of Ketchikan Creek, where a hatchery upstream supports a summer
salmon run. The Creek mouth is more than 4 km (2.5 mi) from both ferry
berth sites, and is positioned behind the cruise ship terminal and
within the small boat harbor. In addition to these locations, anecdotal
information from a local kayaking company suggests that there are
Steller sea lions present at Gravina Point, near the southwest entrance
to Tongass Narrows.
A total of 181 Steller sea lions were sighted on 44 separate days
during all months of Ward Cove Cruise Ship Dock construction (February
through September, 2020) (Power Systems and
[[Page 5991]]
Supplies of Alaska, 2020). Most sightings occurred in February and
March and the fewest sightings were in May. Sightings were of single
individuals, pairs, and herds of up to 10 individuals.
The DOT&PF implemented a marine mammal monitoring program in
Tongass Narrows for recent previous construction components of the
Tongass Narrows Project (84 FR 34134; July 17, 2019). Monitoring took
place from October 2020 through February 2021 and May through June
2021, and results indicated that Steller sea lion numbers were highest
in January and February (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
Steller sea lions were observed in the Tongass Narrows Project area on
49 of 88 days between October 2020 and June 2021 (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). They were observed in every month that
observations took place (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). Over
the course of the 7 months of monitoring, there were 77 sightings of 92
individual animals (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). Sightings
of Steller sea lions were most frequent in January and February and
least common in May and June (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
Sightings were primarily of single animals, but animals were also
present in pairs and groups up to five sea lions (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). This is consistent with Freitag (2017 as cited in
83 FR 22009; May 11, 2018), though groups of up to 80 individuals have
been observed (HDR, Inc. 2003). On average over the course of a year,
Steller sea lions occur in Tongass Narrows approximately three or four
times per week (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
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. In 2010, harbor seals in Alaska were partitioned into
12 separate stocks based largely on genetic structure (Allen and
Angliss 2010). Harbor seals in Tongass Narrows are recognized as part
of the Clarence Strait stock. Distribution of the Clarence Strait stock
ranges from the east coast of Prince of Wales Island from Cape Chacon
north through Clarence Strait to Point Baker and along the east coast
of Mitkof and Kupreanof Islands north to Bay Point, including Ernest
Sound, Behm Canal, and Pearse Canal (Muto et al. 2021). The latest
stock assessment analysis indicates that the current 8-year estimate of
the Clarence Strait population trend is +138 seals per year, with a
probability that the stock is decreasing of 0.413 (Muto et al. 2021).
Harbor seals 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, with local movements
associated with such factors as tides, weather, season, food
availability, and reproduction (Muto, et al. 2021).
No systematic studies of harbor seal abundance or distribution have
occurred in Tongass Narrows. Aerial surveys conducted in August 2011
did not record any harbor seal haulouts in Tongass Narrows, but several
haulouts were located on the outer shores of Gravina Island (London et
al. 2015). There is no known harbor seal haulout in Tongass Narrows
although seals have been observed hauled out on docks in Ketchikan
Harbor. The closest listed haulout is located off the tip of Gravina
Island, approximately 8 km (5 mi) northwest of Ward Cove (AFSC 2018).
Anecdotal observations indicate that harbor seals are common in
Tongass Narrows, although no data exist to quantify abundance. Two
salmon hatcheries operated by ADF&G are located east of the project
area. Like Steller sea lions, harbor seals may aggregate near the mouth
of Ketchikan Creek when salmon are running in summer. The creek mouth
is more than 4 km (2.5 mi) from the project component sites, and is
positioned behind both the cruise ship terminal and within the small
boat harbor. In the project area, they tend to be more abundant during
spring, summer and fall months when salmon are present in Ward Creek.
Anecdotal evidence indicates that harbor seals typically occur in
groups of 1-3 animals in Ward Cove (Spokely 2019). They were not
observed in Tongass Narrows during a combined 63.5 hours of marine
mammal monitoring that took place in 2001 and 2016 (OSSA 2001,
Turnagain 2016). The COK conducted pinnacle rock blasting in December
2019 and January 2020 near the vicinity of the proposed project and
recorded a total of 21 harbor seal sightings of 24 individuals over
76.2 hours of pre- and post-blast monitoring (Sitkiewicz 2020).
Harbor seals were sighted during every month of construction
(February through September, 2020) associated with the Ward Cove Cruise
Ship Dock, with most sightings in February and March and the fewest in
July (Power Systems and Supplies of Alaska, 2020). There were 247
sighting events of 271 individuals. Sighting events were of solo
individuals, pairs, and the occasional group of three.
Marine mammal monitoring occurred near the project site from
October 2020 to February 2021 and resumed in May 2021 during Phase 1 of
the previously issued IHA (85 FR 673; January 7, 2020). Harbor seals
were observed in the Tongass Narrows Project area in every month in
which observations took place, except during October 2020 when only 3
days of monitoring occurred (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
Harbor seals were sighted on 68 days out of 88 days of monitoring
(DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). They were mostly sightings
of single animals, but animals were also present in pairs and groups up
to five seals (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). Sightings of
harbor seals were consistent over the course of 7 months of
intermittent monitoring; they were observed 5 to 6 days per week on
average (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d).
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 5992]]
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 (dolphins, 150 Hz to 160 kHz.
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) (true 50 Hz to 86 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39 kHz.
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 co-occur with
the proposed survey 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 and ziphiid species and
the sperm whale), and two are classified as high-frequency cetaceans
(i.e., harbor porpoise, Dall's porpoise and Kogia spp.).
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 impact and vibratory pile driving and removal and use of
DTH equipment. The effects of underwater noise from ADOT's proposed
activities have the potential to result in Level A or Level B
harassment of marine mammals in the action area.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far (ANSI 1995). The sound level of an area is
defined by the total acoustical energy being generated by known and
unknown sources. These sources may include physical (e.g., waves, wind,
precipitation, earthquakes, ice, atmospheric sound), biological (e.g.,
sounds produced by marine mammals, fish, and invertebrates), and
anthropogenic sound (e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor, and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al. 1995). The result is that, depending
on the source type and its intensity, sound from the specified activity
may be a negligible addition to the local environment or could form a
distinctive signal that may affect marine mammals.
In-water construction activities associated with the project would
include impact pile driving, vibratory pile driving and removal, and
use of DTH equipment. The sounds produced by these activities fall into
one of two general sound types: Impulsive and non-impulsive. Impulsive
sounds (e.g., explosions, gunshots, sonic booms, impact pile driving)
are typically transient, brief (less than 1 second), broadband, and
consist of high peak sound pressure with rapid rise time and rapid
decay (ANSI 1986; NIOSH 1998; NMFS 2018). Non-impulsive sounds (e.g.
aircraft, machinery operations such as drilling or dredging, vibratory
pile driving, and active sonar systems) can be broadband, narrowband or
tonal, brief or prolonged (continuous or intermittent), and typically
do not have the high peak sound pressure with rapid rise/decay time
that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The
distinction between these two sound types is important because they
have differing potential to cause physical effects, particularly with
regard to hearing (e.g., Ward 1997 in Southall et al. 2007).
Three types of hammers would be used on this project: Impact,
vibratory, and DTH. Impact hammers operate by repeatedly dropping and/
or pushing a heavy piston onto a pile to drive the pile into the
substrate. Sound generated by impact hammers is characterized by rapid
rise times and high peak levels, a potentially injurious combination
(Hastings and Popper 2005). Vibratory hammers install piles by
vibrating them and allowing the weight of the hammer to push them into
the sediment. Vibratory hammers produce significantly less sound than
impact hammers. Peak Sound Pressure Levels (SPLs) may be 180 dB or
greater, but are generally 10 to 20 dB lower than SPLs generated during
impact pile driving of the same-sized pile (Oestman et al.
[[Page 5993]]
2009). Rise time is slower, reducing the probability and severity of
injury, and sound energy is distributed over a greater amount of time
(Nedwell and Edwards 2002; Carlson et al. 2005).
A DTH hammer is essentially a drill bit that drills through the
bedrock using a rotating function like a normal drill, in concert with
a hammering mechanism operated by a pneumatic (or sometimes hydraulic)
component integrated into to the DTH hammer to increase speed of
progress through the substrate (i.e., it is similar to a ``hammer
drill'' hand tool). The sounds produced by the DTH method contain both
a continuous non-impulsive component from the drilling action and an
impulsive component from the hammering effect. Therefore, we treat DTH
systems as both impulsive and continuous, non-impulsive sound source
types simultaneously.
The likely or possible impacts of ADOT's proposed activity on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of the equipment and personnel; however, any impacts to marine
mammals are expected to primarily be acoustic in nature. Acoustic
stressors include effects of heavy equipment operation during pile
installation and removal and use of DTH.
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic
environment from pile driving and removal and DTH is the primary means
by which marine mammals may be harassed from ADOT's specified activity.
In general, animals exposed to natural or anthropogenic sound may
experience physical and psychological effects, ranging in magnitude
from none to severe (Southall et al. 2007, 2019). In general, exposure
to pile driving and DTH noise has the potential to result in auditory
threshold shifts and behavioral reactions (e.g., avoidance, temporary
cessation of foraging and vocalizing, changes in dive behavior).
Exposure to anthropogenic noise can also lead to non-observable
physiological responses such an increase in stress hormones. Additional
noise in a marine mammal's habitat can mask acoustic cues used by
marine mammals to carry out daily functions such as communication and
predator and prey detection. The effects of pile driving and DTH noise
on marine mammals are dependent on several factors, including, but not
limited to, sound type (e.g., impulsive vs. non-impulsive), the
species, age and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the pile and the animal,
received levels, behavior at time of exposure, and previous history
with exposure (Wartzok et al. 2004; Southall et al. 2007). Here we
discuss physical auditory effects (threshold shifts) followed by
behavioral effects and potential impacts on habitat.
NMFS defines a noise-induced threshold shift (TS) as a change,
usually an increase, in the threshold of audibility at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS 2018). The amount of
threshold shift is customarily expressed in dB. A TS can be permanent
or temporary. As described in NMFS (2018), there are numerous factors
to consider when examining the consequence of TS, including, but not
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough
duration or to a high enough level to induce a TS, the magnitude of the
TS, time to recovery (seconds to minutes or hours to days), the
frequency range of the exposure (i.e., spectral content), the hearing
and vocalization frequency range of the exposed species relative to the
signal's frequency spectrum (i.e., how animal uses sound within the
frequency band of the signal; e.g., Kastelein et al. 2014), and the
overlap between the animal and the source (e.g., spatial, temporal, and
spectral).
Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent,
irreversible increase in the threshold of audibility at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS 2018). Available data from
humans and other terrestrial mammals indicate that a 40 dB threshold
shift approximates PTS onset (see Ward et al. 1958, 1959; Ward 1960;
Kryter et al. 1966; Miller 1974; Ahroon et al. 1996; Henderson et al.
2008). PTS levels for marine mammals are estimates, as with the
exception of a single study unintentionally inducing PTS in a harbor
seal (Kastak et al. 2008), there are no empirical data measuring PTS in
marine mammals largely due to the fact that, for various ethical
reasons, experiments involving anthropogenic noise exposure at levels
inducing PTS are not typically pursued or authorized (NMFS 2018).
Temporary Threshold Shift (TTS)--A temporary, reversible increase
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS 2018). Based on data from cetacean TTS measurements (see
Southall et al. 2007), a TTS of 6 dB is considered the minimum
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Schlundt et
al. 2000; Finneran et al. 2000, 2002). As described in Finneran (2015),
marine mammal studies have shown the amount of TTS increases with
cumulative sound exposure level (SELcum) in an accelerating fashion: At
low exposures with lower SELcum, the amount of TTS is typically small
and the growth curves have shallow slopes. At exposures with higher
SELcum, the growth curves become steeper and approach linear
relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to serious (similar to those discussed in auditory
masking, below). For example, a marine mammal may be able to readily
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal
is traveling through the open ocean, where ambient noise is lower and
there are not as many competing sounds present. Alternatively, a larger
amount and longer duration of TTS sustained during time when
communication is critical for successful mother/calf interactions could
have more serious impacts. We note that reduced hearing sensitivity as
a simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al. 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without cost.
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 five species of pinnipeds 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
[[Page 5994]]
mammal TTS data come from a limited number of individuals within these
species. No data are 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 Table 5 in
NMFS (2018).
Installing piles requires a combination of impact pile driving,
vibratory pile driving, and DTH. For the project, these activities may
occur at the same time (up to two hammers of any combination of hammer/
drill type), though such an occurrence is anticipated to be infrequent
and for short durations on any given day, given that pile installation
and removal occurs intermittently to allow for adjusting piles and
measuring and documenting progress. Therefore, there would likely be
pauses in activities producing the sound during each day. Given these
pauses and that many marine mammals are likely moving through the
project area and not remaining for extended periods of time, the
potential for TS declines.
Behavioral Harassment--Exposure to noise from pile driving and
removal and DTH also has the potential to behaviorally disturb marine
mammals. Available studies show wide variation in response to
underwater sound; therefore, it is difficult to predict specifically
how any given sound in a particular instance might affect marine
mammals perceiving the signal. If a marine mammal does react briefly to
an underwater sound by changing its behavior or moving a small
distance, the impacts of the change are unlikely to be significant to
the individual, let alone the stock or population. However, if a sound
source displaces marine mammals from an important feeding or breeding
area for a prolonged period, impacts on individuals and populations
could be significant (e.g., Lusseau and Bejder 2007; Weilgart 2007; NRC
2005).
Disturbance may result in changing durations of surfacing and
dives, number of blows per surfacing, or moving direction and/or speed;
reduced/increased vocal activities; changing/cessation of certain
behavioral activities (such as socializing or feeding); visible startle
response or aggressive behavior (such as tail/fluke slapping or jaw
clapping); avoidance of areas where sound sources are located.
Pinnipeds may increase their haul out time, possibly to avoid in-water
disturbance (Thorson and Reyff 2006). Behavioral responses to sound are
highly variable and context-specific and any reactions depend on
numerous intrinsic and extrinsic factors (e.g., species, state of
maturity, experience, current activity, reproductive state, auditory
sensitivity, time of day), as well as the interplay between factors
(e.g., Richardson et al. 1995; Wartzok et al. 2003; Southall et al.
2007; Weilgart 2007; 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 (Ellison et al. 2012), and can vary depending on
characteristics associated with the sound source (e.g., whether it is
moving or stationary, number of sources, distance from the source). In
general, pinnipeds seem more tolerant of, or at least habituate more
quickly to, potentially disturbing underwater sound than do cetaceans,
and generally seem to be less responsive to exposure to industrial
sound than most cetaceans. Please see Appendices B and C of Southall et
al. (2007) for a review of studies involving marine mammal behavioral
responses to sound.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.
2001; Nowacek et al. 2004; Madsen et al. 2006; Yazvenko et al. 2007). A
determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
In 2016, ADOT documented observations of marine mammals during
construction activities (i.e., pile driving and DTH) at the Kodiak
Ferry Dock (ABR 2016) in the Gulf of Alaska. In the marine mammal
monitoring report for that project, 1,281 Steller sea lions were
observed within the estimated Level B harassment zone during pile
driving or DTH (i.e., documented as potential take by Level B
harassment). Of these, 19 individuals demonstrated an alert behavior, 7
were fleeing, and 19 swam away from the project site. All other animals
(98 percent) were engaged in activities such as milling, foraging, or
fighting and did not change their behavior. In addition, two sea lions
approached within 20 m of active vibratory pile driving activities.
Three harbor seals were observed within the disturbance zone during
pile driving activities; none of them displayed disturbance behaviors.
Fifteen killer whales and three harbor porpoise were also observed
within the Level B harassment zone during pile driving. The killer
whales were travelling or milling while all harbor porpoises were
travelling. No signs of disturbance were noted for either of these
species. Given the similarities in species, activities, and habitat, we
expect similar behavioral responses of marine mammals to the ADOT's
specified activity. That is, disturbance, if any, is likely to be
temporary and localized (e.g., small area movements). Monitoring
reports from other recent pile driving and DTH projects in Alaska have
observed similar behaviors, for example, the Biorka Island Dock
Replacement Project (<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-faa-biorka-island-dock-replacement-project-sitka-ak">https://www.fisheries.noaa.gov/action/incidental-take-authorization-faa-biorka-island-dock-replacement-project-sitka-ak</a>).
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
[[Page 5995]]
``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), however
distress is an unlikely result of this project based on observations of
marine mammals during previous, similar projects in the area.
Masking--Sound can disrupt behavior through masking, or interfering
with, an animal's ability to detect, recognize, or discriminate between
acoustic signals of interest (e.g., those used for intraspecific
communication and social interactions, prey detection, predator
avoidance, navigation) (Richardson et al. 1995). Masking occurs when
the receipt of a sound is interfered with by another coincident sound
at similar frequencies and at similar or higher intensity, and may
occur whether the sound is natural (e.g., snapping shrimp, wind, waves,
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar,
seismic exploration) in origin. The ability of a noise source to mask
biologically important sounds depends on the characteristics of both
the noise source and the signal of interest (e.g., signal-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. Masking of natural sounds can result when human activities
produce high levels of background sound at frequencies important to
marine mammals. Conversely, if the background level of underwater sound
is high (e.g., on a day with strong wind and high waves), an
anthropogenic sound source would not be detectable as far away as would
be possible under quieter conditions and would itself be masked.
Airborne Acoustic Effects--Pinnipeds that occur near the project
site could be exposed to airborne sounds associated with pile driving
and removal and DTH that have the potential to cause behavioral
harassment, depending on their distance from these activities.
Cetaceans are not expected to be exposed to airborne sounds that would
result in harassment as defined under the MMPA.
Airborne noise would primarily be an issue for pinnipeds that are
swimming or hauled out near the project site within the range of noise
levels elevated above the acoustic criteria. We recognize that
pinnipeds in the water could be exposed to airborne sound that may
result in behavioral harassment when looking with their heads above
water. Most likely, airborne sound would cause behavioral responses
similar to those discussed above in relation to underwater sound. For
instance, anthropogenic sound could cause hauled-out pinnipeds to
exhibit changes in their normal behavior, such as reduction in
vocalizations, or cause them to temporarily abandon the area and move
further from the source. However, these animals would previously have
been `taken' because of exposure to underwater sound above the
behavioral harassment thresholds, which are in all cases larger than
those associated with airborne sound. Thus, the behavioral harassment
of these animals is already accounted for in these estimates of
potential take. Therefore, we do not believe that authorization of
incidental take resulting from airborne sound for pinnipeds is
warranted, and airborne sound is not discussed further here.
Marine Mammal Habitat Effects
ADOT's proposed activities at the project area would not result in
permanent negative impacts to habitats used directly by marine mammals,
but may have potential short-term impacts to food sources such as
forage fish and may affect acoustic habitat (see masking discussion
above). There are no known foraging hotspots or other ocean bottom
structure of significant biological importance to marine mammals
present in the marine waters of the project area during the
construction window, but there are times of increased foraging during
periods of forage fish and salmonid spawning. ADOT's construction
activities in Tongass Narrows could have localized, temporary impacts
on marine mammal habitat and their prey by increasing in-water sound
pressure levels and slightly decreasing water quality. Increased noise
levels may affect acoustic habitat (see masking discussion above) and
adversely affect marine mammal prey in the vicinity of the project area
(see discussion below). During DTH, impact and vibratory pile driving
or removal, elevated levels of underwater noise would ensonify a
portion of Tongass Narrows and nearby waters where both fishes and
mammals occur and could affect foraging success. Additionally, marine
mammals may avoid the area during construction, however, displacement
due to noise is expected to be temporary and is not expected to result
in long-term effects to the individuals or populations. Construction
activities are of short duration and would likely have temporary
impacts on marine mammal habitat through increases in underwater and
airborne sound.
The area likely impacted by the project includes much of Tongass
Narrows, but overall this area is relatively small compared to the
available habitat in the surrounding area including Revillagigedo
Channel, Behm Canal, and Clarence Strait. Pile installation/removal and
DTH may temporarily increase turbidity resulting from suspended
sediments. Any increases would be temporary, localized, and minimal. In
general, turbidity associated with pile installation is localized to
about a 25-ft radius around the pile (Everitt et al. 1980). Cetaceans
are not expected to be close enough to the project pile driving areas
to experience effects of turbidity, and pinnipeds could avoid localized
areas of turbidity. Therefore, the impact from increased turbidity
levels is expected to minimal for marine mammals. Furthermore, pile
driving and removal at the project site would not obstruct movements or
migration of marine mammals.
In-water Construction Effects on Potential Prey--Construction
activities
[[Page 5996]]
would produce continuous (i.e., vibratory pile driving and DTH) and
intermittent (i.e. impact driving and DTH) sounds. 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. Here, we describe studies regarding the effects of noise on
known marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick and Mann 1999; Fay 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al. 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds that are especially strong and/or intermittent
low-frequency sounds. Short duration, sharp sounds can cause overt or
subtle changes in fish behavior and local distribution. The reaction of
fish to noise depends on the physiological state of the fish, past
exposures, motivation (e.g., feeding, spawning, migration), and other
environmental factors. Hastings and Popper (2005) identified several
studies that suggest fish may relocate to avoid certain areas of sound
energy. Additional studies have documented effects of pile driving on
fish; 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).
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 and removal and
DTH activities at the project area would be temporary behavioral
avoidance of the area. The duration of fish avoidance of this area
after pile driving stops is unknown, but a rapid return to normal
recruitment, distribution and behavior is anticipated. Any behavioral
avoidance by fish of the disturbed area would still leave significantly
large areas of fish and marine mammal foraging habitat in the nearby
vicinity in Revillagigedo Channel, Behm Canal, and Clarence Strait.
Additionally, the City of Ketchikan within Tongass Narrows has a busy
industrial water front, and human impact lessens the value of the area
as foraging habitat. There are times of known seasonal marine mammal
foraging in Tongass Narrows around fish processing/hatchery
infrastructure or when fish are congregating, but the impacted areas of
Tongass Narrows are a small portion of the total foraging habitat
available in the region. In general, impacts to marine mammal prey
species are expected to be minor and temporary due to the short
timeframe of the project.
Construction activities, in the form of increased turbidity, have
the potential to adversely affect eulachon, herring, and juvenile
salmonid outmigratory routes in the project area. Salmon and forage
fish, like eulachon and herring, form a significant prey base for
Steller sea lions and are major components of the diet of many other
marine mammal species that occur in the project area. Increased
turbidity is expected to occur only in the immediate vicinity of
construction activities and to dissipate quickly with tidal cycles.
Given the limited area affected and high tidal dilution rates any
effects on fish are expected to be minor.
Additionally, the presence of transient killer whales means some
marine mammal species are also possible prey (harbor seals, harbor
porpoises). ADOT's pile driving, pile removal and DTH activities are
expected to result in limited instances of take by Level B and Level A
harassment on these smaller marine mammals. That, as well as the fact
that ADOT is impacting a small portion of the total available marine
mammal habitat means that there would be minimal impact on these marine
mammals as prey.
In summary, given the short daily duration of sound associated with
individual pile driving and DTH events and the small area being
affected relative to available nearby habitat, pile driving and DTH
activities associated with the proposed action are not likely to have a
permanent, adverse effect on any fish habitat, or populations of fish
species or other prey. Thus, we conclude that impacts of the specified
activity are not likely to have more than short-term adverse effects on
any prey habitat or populations of prey species. Further, any impacts
to marine mammal habitat are not expected to result in significant or
long-term consequences for individual marine mammals, or to contribute
to adverse impacts on their populations.
Estimated Take
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.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of the acoustic sources (i.e., impact and vibratory pile driving and
DTH) have the potential to result in disruption of behavioral patterns
for individual marine mammals. There is also some potential for
auditory injury (Level A harassment) to result, primarily for
mysticetes, high frequency species and phocids because predicted
auditory injury zones are larger than for mid-frequency species and
otariids. Auditory injury is unlikely to occur for mid-frequency
species and otariids. The proposed mitigation and monitoring
[[Page 5997]]
measures are expected to minimize the severity of such taking to the
extent practicable.
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
NMFS recommends the use of acoustic thresholds that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur PTS of some degree (equated to Level A
harassment).
Level B Harassment for non-explosive sources--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 microPascal ([mu]Pa) (root mean square (rms)) for
continuous (e.g., vibratory pile-driving, DTH) and above 160 dB re 1
[mu]Pa (rms) for non-explosive impulsive (e.g., seismic airguns) or
intermittent (e.g., scientific sonar) sources. This take estimation
includes disruption of behavioral patterns resulting directly in
response to noise exposure (e.g., avoidance), as well as that resulting
indirectly from associated impacts such as TTS or masking. ADOT's
proposed activity includes the use of continuous (vibratory pile
driving/removal and DTH) and impulsive (impact pile driving and DTH)
sources, and therefore both the 120 and 160 dB re 1 [mu]Pa (rms)
thresholds are applicable.
Level A harassment for non-explosive sources--NMFS' Technical
Guidance for Assessing the Effects of Anthropogenic Sound on Marine
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual
criteria to assess auditory injury (Level A harassment) to five
different marine mammal groups (based on hearing sensitivity) as a
result of exposure to noise from two different types of sources
(impulsive or non-impulsive). ADOT's proposed activity includes the use
of impulsive (impact pile driving and DTH) and non-impulsive (vibratory
pile driving/removal and DTH) sources.
These thresholds 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>.
Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
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.
The sound field in the project area is the existing background
noise plus additional construction noise from the proposed project.
Marine mammals are expected to be affected via sound generated by the
primary components of the project (i.e., impact pile driving, vibratory
pile driving, vibratory pile removal, and DTH).
In order to calculate distances to the Level A harassment and Level
B harassment sound thresholds for the methods and piles being used in
this project, NMFS used acoustic monitoring data from other locations
to develop source levels for the various pile types,
[[Page 5998]]
sizes and methods (Table 5). Note that piles of differing sizes have
different sound source levels (SSLs).
Empirical data from recent ADOT sound source verification (SSV)
studies at Ketchikan were used to estimate SSLs for vibratory and
impact driving of 30-inch steel pipe piles (Denes et al. 2016). Data
from Ketchikan was used because of its proximity to this proposed
project in Tongass Narrows. However, the use of data from Alaska sites
was not appropriate in all instances. Details are described below.
For vibratory driving of 24-inch steel piles, data from a Navy pile
driving project in the Puget Sound, WA was reviewed (Navy 2015). From
this review, ADOT determined the Navy's suggested source value of 161
dB rms was an appropriate proxy source value, and NMFS concurs. Because
the source value of smaller piles of the same general type (steel in
this case) are not expected to exceed a larger pile, the same 161 dB
rms source value was used for 20-inch steel piles. This assumption
conforms with source values presented in Navy (2015) for a project
using 16-inch steel piles at Naval Base Kitsap in Bangor, WA.
ADOT used source values of 177 dB SEL and 190 dB rms for impact
driving of 24-inch and 20-inch steel piles. These values were
determined based on summary values presented in Caltrans (2015) for
impact driving of 24-inch steel piles. NMFS concurs that the same
source value was an acceptable proxy for impact driving of 20-inch
steel piles.
Sound pressure levels in the water column resulting from DTH are
not well studied. Because DTH hole creation includes both impulsive and
continuous components, NMFS guidance currently recommends that it be
treated as a continuous sound for Level B calculations and as an
impulsive sound for Level A calculations (Table 11). In the absence of
data specific to different hole sizes, current NMFS guidance recommends
that calculation of Level B zones for DTH use the same continuous SSL
of 167 dB SEL for all hole sizes (Heyvaert and Reyff 2021). Recommended
SSLs for 30-inch and 24-inch holes as well as 8-inch holes for tension
anchors and micropiles for use in the calculation of Level A harassment
thresholds are provided by current NMFS guidance and in Table 5.
Table 5--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, DTH,
and Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Method and pile type SSL at 10 m Literature source
Vibratory hammer dB rms ........................
----------------------------------------------------------------------------------------------------------------
30-inch steel piles................... 162 Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch steel piles................... 161 Navy 2015.
----------------------------------------------------------------------------------------------------------------
20-inch steel piles................... 161 Navy 2015.
----------------------------------------------------------------------------------------------------------------
DTH of rock sockets and tension dB rms
anchors
----------------------------------------------------------------------------------------------------------------
All pile diameters.................... 167 Heyvaert and Reyff 2021.
----------------------------------------------------------------------------------------------------------------
DTH of rock sockets and tension
anchors dB SELss dB peak
----------------------------------------------------------------------------------------------------------------
30-inch rock socket.................. 164 194 Reyff and Heyvaert
2019; Reyff 2020;
Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch rock socket.................. 159 184 Heyvaert and Reyff
2021.
----------------------------------------------------------------------------------------------------------------
8-inch tension anchor/micropile...... 144 170 Reyff 2020.
----------------------------------------------------------------------------------------------------------------
Impact hammer dB rms dB SEL dB peak
----------------------------------------------------------------------------------------------------------------
30-inch steel piles................. 195 181 209 Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch steel piles................. 190 177 203 Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
20-inch steel piles................. 190 177 202 Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
Note: It is assumed that noise levels during pile installation and removal are similar. SEL = sound exposure
level; dB peak = peak sound level; rms = root mean square.
Simultaneous use of two impact, vibratory, or DTH hammers, or any
combination of those equipment, could occur. Such occurrences are
anticipated to be infrequent, would be for short durations on any given
day, and ADOT anticipates that no more than two hammers would be
operated concurrently. Simultaneous use of two hammers or DTH systems
could occur at the same project site, or at two different, but nearby
project sites. Simultaneous use of hammers could result in increased
SPLs and harassment zone sizes given the proximity of the component
driving sites and the physical rules of decibel addition. ADOT
anticipates that concurrent use of two hammers producing continuous
noise could occur on 44 days, which is half the anticipated number of
days of construction (91 days) and represents complete overlap between
the two contracts and/or represents use of two hammers by a single
contractor. Although it is unlikely that overlap would be complete,
ADOT anticipates, and NMFS concurs, this scenario represents the
potential worst case scenario, given that a more accurate estimate is
not possible, and concurrent operation of hammers would be incidental.
Given that the use of more than one hammer for pile installation on the
same day (whether simultaneous or not) would increase the number of
piles installed per day, this would be anticipated to result in a
reduction of the total number of days of pile installation. Table 6
shows how potential scenarios would reduce the total number of pile
driving days and weeks. However, as described in the Marine Mammal
Occurrence and Take Calculation and Estimation section below, ADOT has
conservatively calculated take with the assumption that pile driving
would occur on all 91 days.
[[Page 5999]]
Table 6--Calculated Reduction of Pile Driving Days Based on Percentage of Project Days With Two Hammers in Use
----------------------------------------------------------------------------------------------------------------
Days of work
Days of completed Remaining days Total number
Percent overlap overlap during overlap of work with of days of Weeks of work
(2 hammers) single hammer work
----------------------------------------------------------------------------------------------------------------
0............................... 0.0 0.0 91.0 91.0 15.2
10.............................. 9.1 18.2 72.8 81.9 13.7
20.............................. 18.2 36.4 54.6 72.8 12.1
30.............................. 27.3 54.6 36.4 63.7 10.6
40.............................. 36.4 72.8 18.2 54.6 9.1
50.............................. 45.5 91.0 0.0 45.5 7.6
----------------------------------------------------------------------------------------------------------------
NMFS (2018b) handles overlapping sound fields created by the use of
more than one hammer differently for impulsive (impact hammer and Level
A harassment zones for drilling with a DTH hammer) and continuous sound
sources (vibratory hammer and Level B harassment zones for drilling
with a DTH hammer; Table 7) and differently for impulsive sources with
rapid impulse rates of multiple strikes per second (DTH) and slow
impulse rates (impact hammering) (NMFS 2021). It is unlikely that the
two impact hammers would strike at the same instant, and therefore, the
SPLs would not be adjusted regardless of the distance between impact
hammers. In this case, each impact hammer would be considered to have
its own independent Level A harassment and Level B harassment zones.
When two DTH hammers operate simultaneously their continuous sound
components overlap completely in time. When the Level B isopleth of one
DTH sound source encompasses the isopleth of another DTH sound source,
the sources are considered additive and combined using the following
rules (Table 7). The method described below was based on one created by
Washington State Department of Transportation (WSDOT) and has been
updated and modified by NMFS (WSDOT 2020). For addition of two
simultaneous DTH hammers, the difference between the two SSLs is
calculated, and if that difference is between 0 and 1 dB, 3 dB are
added to the higher SSL; if difference is between 2 or 3 dB, 2 dB are
added to the highest SSL; if the difference is between 4 to 9 dB, 1 dB
is added to the highest SSL; and with differences of 10 or more
decibels, there is no addition.
When two continuous noise sources, such as vibratory hammers, have
overlapping sound fields, there is potential for higher sound levels
than for non-overlapping sources.
When two or more vibratory hammers are used simultaneously, and the
isopleth of one sound source encompasses the isopleth of another sound
source, the sources are considered additive and source levels are
combined using the rules in Table 7, similar to described above for
DTH.
Table 7--Rules for Combining Sound Source Levels Generated During Pile Installation
----------------------------------------------------------------------------------------------------------------
Hammer types Difference in SSL Level A zones Level B zones
----------------------------------------------------------------------------------------------------------------
Vibratory, Impact................. Any.................. Use impact zones.......... Use largest zone.
Impact, Impact.................... Any.................. Use zones for each pile Use zone for each pile
size and number of size.
strikes.
Vibratory, Vibratory or DTH, DTH.. 0 or 1 dB............ Add 3 dB to the higher Add 3 dB to the higher
2 or 3 dB............ source level. source level.
Add 2 dB to the higher Add 2 dB to the higher
source level. source level.
4 to 9 dB............ Add 1 dB to the higher Add 1 dB to the higher
10 dB or more........ source level. source level.
Add 0 dB to the higher Add 0 dB to the higher
source level. source level.
----------------------------------------------------------------------------------------------------------------
During pile driving, it is common for pile installation to start
and stop multiple times as each pile is adjusted and its progress is
measured and documented, though as stated above, for short durations,
it is anticipated that multiple hammers could be in use simultaneously.
Following an approach modified from WSDOT in their Biological
Assessment manual (WSDOT 2020) and described in Table 8, decibel
addition calculations were carried out for possible combinations of
pile driving and DTH throughout the project area. The source levels
included in Table 8 are used to estimate the Level A harassment zones
and the Level B harassment zones.
Table 8--Combined SSLs (dB at 10 m) Generated During Pile Installation and Removal for Combinations of Two Pieces of Equipment: Impact Hammer, Vibratory
Hammer, and Down-the-Hole Drill
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory (RMS) DTH (RMS) DTH (SEL)
--------------------------------------------------------------------------------------------------
Method Pile diameter 20 24 30 8 24 30 8 24 30
--------------------------------------------------------------------------------------------------
SSL 161 161 162 167 167 167 144 159 164
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory (RMS)...................................... 20 161 164 164 165 168 168 168 ....... ....... .......
24 161 164 164 165 168 168 168 ....... ....... .......
30 162 165 165 165 168 168 168 ....... ....... .......
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (RMS)............................................ 8 167 168 168 168 170 170 170 ....... ....... .......
[[Page 6000]]
24 167 168 168 168 170 170 170 ....... ....... .......
30 167 168 168 168 170 170 170 ....... ....... .......
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH (SEL)............................................ 8 144 ....... ....... ....... ....... ....... ....... 147 159 164
24 159 ....... ....... ....... ....... ....... ....... 159 162 165
30 164 ....... ....... ....... ....... ....... ....... 164 165 167
--------------------------------------------------------------------------------------------------------------------------------------------------------
No addition is warranted for impact pile driving in combination
with vibratory or impact pile driving or DTH (NMFS 2021).
Level B Harassment Zones
Transmission loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source. TL parameters vary
with frequency, temperature, sea conditions, current, source and
receiver depth, water depth, water chemistry, and bottom composition
and topography. The general formula for underwater TL is:
TL = B * Log10 (R1/R2),
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement
The recommended TL coefficient for most nearshore environments is
the practical spreading value of 15. This value results in an expected
propagation environment that would lie between spherical and
cylindrical spreading loss conditions, which is the most appropriate
assumption for ADOT's proposed activity in the absence of specific
modelling.
All Level B harassment isopleths are reported in Table 9 and Table
10 below. It should be noted that based on the geography of Tongass
Narrows and the surrounding islands, sound would not reach the full
distance of the Level B harassment isopleth in most directions.
Generally, due to interaction with land, only a thin slice of the
possible area is ensonified to the full distance of the Level B
harassment isopleth.
The size of the Level B harassment zone during concurrent operation
of two vibratory or DTH hammers would depend on the combination of
sound sources and the decibel addition of two hammers producing
continuous noise. Table 9 shows the distances to Level B harassment
isopleths during simultaneous hammering from two sources, based on the
combined SSL. Because the calculated Level B harassment isopleths for
two sources are dependent upon the combined SSL, the Level B harassment
zone for each combined sound source level included in Table 9 is
consistent, regardless of the equipment combination. Please refer to
Table 8 to determine which sound sources apply to each Combined SSL.
As noted previously, pile installation often involves numerous
stops and starts of the hammer for each pile. Therefore, decibel
addition is applied only when the adjacent continuous sound sources
experience overlapping sound fields, which generally requires close
proximity of driving locations.
Table 9-- Level B Harassment Isopleths for Multiple Vibratory Hammer
Additions
------------------------------------------------------------------------
Level B
harassment
Combined SSL (dB) isopleth (m)
\a\
------------------------------------------------------------------------
164..................................................... 8,577
165..................................................... 10,000
166..................................................... 11,659
167..................................................... 13,594
168..................................................... 15,849
169..................................................... 18,478
170..................................................... 21,544
------------------------------------------------------------------------
\a\ These larger zones are truncated to the southeast by islands, which
prevent propagation of sound in that direction beyond the confines of
Tongass Narrows. To the northwest of Tongass Narrows, combined sound
levels that exceed 167 dB rms extend into Clarence Strait before
attenuating to sound levels that are anticipated to be below 120 dB
rms.
Table 10--Level B Harassment Isopleths for Single Hammer Use by Activity
and Pile Size
------------------------------------------------------------------------
Level B
Activity Pile diameter harassment
(inch) isopleth (m)
------------------------------------------------------------------------
Vibratory Installation.................. 30 6,310
24 5,412
20 ..............
Vibratory Removal....................... 24 ..............
DTH Rock Sockets........................ 30 13,594
[[Page 6001]]
24 ..............
DTH Tension Anchor/Micropile............ 8 ..............
Impact Installation..................... 30 2,154
24 1,000
20 1,000
------------------------------------------------------------------------
Level A Harassment Zones
When the NMFS Technical Guidance (2016) was published, 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 takes by Level A harassment. 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
pile driving or removal and DTH using any of the methods discussed
above, NMFS User Spreadsheet predicts the closest distance at which, if
a marine mammal remained at that distance the whole duration of the
activity, it would incur PTS. Inputs used in the User Spreadsheet are
reported in Table 11 and Table 12, and the resulting isopleths are
reported below in Table 13 and Table 14. Pile installation and removal
can occur at variable rates, from a few minutes one day to many hours
the next. ADOT anticipates that one permanent pile would be installed
per day on 27 non-consecutive days, two temporary piles would be
installed per day on 10 non-consecutive days, and two temporary piles
would be removed per day on 10 days.
BILLING CODE 3510-22-P
[[Page 6002]]
[GRAPHIC] [TIFF OMITTED] TN02FE22.002
BILLING CODE 3510-22-C
Regarding implications for Level A harassment zones when two
vibratory hammers are operating concurrently, given the small size of
the estimated Level A harassment isopleths for all hearing groups
during vibratory pile driving, the zone of any two hammers would not be
expected to overlap. Therefore, compounding effects of multiple
vibratory hammers operating concurrently are not anticipated, and NMFS
has treated each source independently.
Regarding implications for Level A harassment zones when one
vibratory hammer and one DTH hammer are operating concurrently,
combining isopleths for these sources is difficult for a variety of
reasons. First, vibratory pile driving relies upon non-impulsive PTS
thresholds, while DTH/rock hammers use impulsive thresholds. Second,
vibratory pile driving account for the duration to drive a pile, while
DTH account for strikes per pile. Thus, it is difficult to measure
sound on the same scale and combine isopleths from these impulsive and
non-impulsive, continuous sources. Therefore, NMFS has treated each
source independently at this time.
Regarding the operation of two DTH hammers concurrently, since DTH
hammers are capable of multiple strikes per second, there is potential
for multiple DTH/rock hammer sources' isopleths to overlap in space and
time (a higher strike rate indicates a greater potential for overlap).
Therefore, NMFS has calculated distances to Level A harassment
isopleths, by hearing group
[[Page 6003]]
for simultaneous use of two DTH hammers (Table 14), using NMFS' User
Spreadsheet. The inputs for these calculations are outlined in Table
12. When the Level A isopleth of one DTH sound source encompasses the
isopleth of another DTH sound source, the sources are considered
additive and combined using the rules in Table 7 as described above.
The number of piles per day is altered to reflect only a single pile
for all those that overlap in space and time (i.e., no double counting
of overlapping piles). The maximum strike rate and duration of the two
DTH systems is used in the User Spreadsheet calculations.
Table 12--NMFS User Spreadsheet Inputs for Simultaneous Use of Two DTH
Hammers
------------------------------------------------------------------------
E.2) DTH pile
Spreadsheet tab used driving
------------------------------------------------------------------------
Weighting Factor Adjustment (kHz)....................... 2
SSL (dB SEL at 10m): \a\
8-in pile/8-in pile................................. 147
8-in pile, 24-in pile............................... 159
8-in pile, 30-in pile............................... 164
24-in pile, 24-in pile.............................. 162
24-in pile, 30-in pile.............................. 165
30-in pile, 30-in pile.............................. 167
Activity duration (minutes) within 24 hours \b\......... 240
Number of piles per day \b\............................. 1
Strike rate (strikes per second)........................ \c\ 15 or
25.83
------------------------------------------------------------------------
\a\ SSL reflects the combined SSLs calculated in Table 8.
\b\ ADOT anticipates that DTH could occur at one site for up to 10 hours
(600 minutes) per day, and overlap between two sites could occur for
up to 4 hours (240 minutes) per day. Since the potential overlap in
sources is accounted for in the SSL adjustment, and the total
potential duration (even with two hammers) is accounted for in the
``Activity duration (minutes) within 24 hours,'' the ``Number of piles
per day'' is assumed to be 1.
\c\ 25.83 for combinations that include 8-in piles. 15 for all other
combinations.
Level A harassment thresholds for impulsive sound sources (impact
pile driving and DTH) are defined for both SELcum and Peak SPL with the
threshold that results in the largest modeled isopleth for each marine
mammal hearing group used to establish the Level A harassment isopleth.
In this project, Level A harassment isopleths based on SELcum were
always larger than those based on Peak SPL (for both single hammer use
and simultaneous use of two hammers). It should be noted that there is
a duration component when calculating the Level A harassment isopleth
based on SELcum, and this duration depends on the number of piles that
would be driven in a day and strikes per pile. For some activities,
ADOT has proposed to drive variable numbers of piles per day throughout
the project (See ``Average Piles per Day (Range)'' in Table 1), and
determine at the beginning of each pile driving day, the maximum number
or duration piles would be driven that day. Here, this flexibility has
been accounted for by modeling multiple durations for the activity, and
determining the relevant isopleths.
Table 13--Distances to Level A Harassment Isopleths, by Hearing Group, and Area of Level A Harassment Zones, for Single Hammer Use During Pile
Installation and Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment isopleth (m) Level A
------------------------------------------------------- harassment
Activity Pile Minutes per pile or areas (km\2\)
diameter(s) strikes per pile LF MF HF PW OW all hearing
groups \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation............... 30 60 minutes................ 8 1 12 5 1 <0.1
\b\ 24 60 minutes................ 7 1 11 5 1 <0.1
20 60 minutes................ 7 1 11 5 1 <0.1
Vibratory Removal.................... 24 60 minutes................ 7 1 11 5 1 <0.1
DTH Rock Sockets..................... 30 60 minutes................ 773 28 920 414 31 <0.9
300 minutes............... 2,258 81 2,690 1,209 88 <3.5
600 minutes............... 3,584 128 4,269 1,918 140 <6.6
24 60 minutes................ 359 13 427 192 15 <0.2
300 minutes............... 1,048 38 1,249 561 41 <1.4
600 minutes............... 1,664 60 1,982 891 65 <2.4
DTH Tension Anchor................... 8 120 minutes............... 82 3 98 44 4 <0.1
240 minutes............... 130 5 155 70 6 <0.1
Impact Installation.................. 30 50 strikes................ 100 4 119 54 4 <0.1
24 50 strikes................ 54 2 65 29 3 <0.1
20 50 strikes................ 54 2 65 29 3 <0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Please refer to Table 6-4 of ADOT's IHA application for hearing group-specific areas.
\b\ Includes vibratory installation and removal.
[[Page 6004]]
Table 14--Distances to Level A Harassment Isopleths, by Hearing Group for Simultaneous Use of Two DTH Hammers
----------------------------------------------------------------------------------------------------------------
Level A harassment isopleth (m)
Activity combination -------------------------------------------------------------------------------
LF MF HF PW OW
----------------------------------------------------------------------------------------------------------------
8-in pile, 8-in pile............ 206 7 245 110 8
8-in pile, 24-in pile........... 1,297 46 1,545 694 51
8-in pile, 30-in pile........... 2,796 99 3,329 1,496 109
24-in pile, 24-in pile.......... 1,431 51 1,705 766 56
24-in pile, 30-in............... 2,268 81 2,702 1,214 88
30-in pile, 30-in pile.......... 3,084 110 3,673 1,650 120
----------------------------------------------------------------------------------------------------------------
Regarding implications for impact hammers used in combination with
a vibratory hammer or DTH drill, the likelihood of these multiple
sources' isopleths to completely overlap in time is slim primarily
because impact pile driving is intermittent. Furthermore, non-
impulsive, continuous sources rely upon non-impulsive TTS/PTS
thresholds, while impact pile driving uses impulsive thresholds, making
it difficult to calculate isopleths that may overlap from impact
driving and the simultaneous action of a non-impulsive continuous
source or one with multiple strikes per second. Thus, with such slim
potential for multiple different sources' isopleths to overlap in space
and time, specifications should be entered as ``normal'' into the User
Spreadsheet for each individual source separately.
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. Additionally, we describe how the occurrence information
is brought together to produce a quantitative take estimate for each
phase. A summary of proposed take, including as a percentage of
population for each of the species, is shown in Table 15.
Steller Sea Lion
Steller sea lion abundance in the Tongass Narrows area is not well
known. No systematic studies of Steller sea lions have been conducted
in or near the Tongass Narrows area. Steller sea lions are known to
occur year-round and local residents report observing Steller sea lions
approximately once or twice per week (based on communication outlined
in Section 6 of ADOT's IHA application). Abundance appears to increase
during herring runs (March to May) and salmon runs (July to September).
Group sizes may reach up to 6 to 10 individuals (Freitag 2017 as cited
in 83 FR 37473; August 1, 2018), though groups of up to 80 individuals
have been observed (HDR, Inc. 2003).
ADOT conservatively estimates that one group of 10 Steller sea
lions may be present in the project area each day, but this occurrence
rate may as much as double (20 Steller sea lions per day) during
periods of increased abundance associated with the herring and salmon
runs (March to May and July to September). Therefore, ADOT anticipates
that two large groups (20 individuals) may be taken by Level B
harassment each day during these months. To be conservative, we assume
all 91 days of work could be completed during these months of increased
abundance and thus estimate 1,820 potential takes by Level B harassment
of Steller sea lions in Tongass Narrows (i.e., 2 groups of 10 sea lions
per day x 91 construction days = 1,820 takes by Level B harassment;
Table 15).
ADOT estimates that simultaneous use of two hammers (any
combination) could occur on up to 44 days during the project. On those
days, Level B harassment zones would extend into Clarence Strait.
Steller sea lions are known to swim across Clarence Strait and to use
offshore areas with deeper waters, although no estimates of at-sea
density or abundance in Clarence Strait are available. Therefore, ADOT
has conservatively estimated, and NMFS concurs, that during the 44 days
with potential simultaneous use of two hammers, a group of 10 Steller
sea lions may occur in the portion of the Level B harassment zone in
Clarence Strait each day (one group of 10 sea lions per day x 44 days =
440 individuals). Therefore, the preliminary sum of estimated takes by
Level B harassment of Steller sea lions between Tongass Narrows and
Clarence Strait is 2,260 (1,820 + 440 = 2,260 takes by Level B
harassment).
The largest Level A harassment zone for otariid pinnipeds could
extend 140 m from the noise source for 10 hours of DTH using a single
hammer, or 120 m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types would occur on
no more than 44 days). Zones for shorter durations and other activities
would be smaller (Table 13). For some DTH activities, the estimated
Level A harassment zone is larger than the proposed shutdown zone, and
therefore, some Level A harassment could occur. Further, while
unlikely, it is possible that a Steller sea lion could enter a shutdown
zone without detection given the various obstructions along the
shoreline, and remain in the zone long enough to be taken by Level A
harassment before being observed and a shutdown occurring. ADOT
therefore requests, and NMFS proposes to authorize, one take by Level A
harassment on each of the 91 construction days (91 takes by Level A
harassment). Take by Level B harassment proposed for authorization was
calculated as the total calculated Steller sea lion takes by Level B
harassment minus the takes by Level A harassment (2,260 takes-91 takes
by Level A harassment) for a total of 2,169 takes by Level B
harassment. Therefore, ADOT requests, and NMFS proposes to authorize,
91 takes of Steller sea lion by Level A harassment and 2,169 takes of
Steller sea lion by Level B harassment (2,260 total takes of Steller
sea lion; Table 15).
Harbor Seal
Harbor seal densities in the Tongass Narrows area are not well
known. No systematic studies of harbor seals have been conducted in or
near Tongass Narrows. They are known to occur year-round with little
seasonal variation in abundance (Freitag 2017 as cited in 83 FR 37473;
August 1, 2018) and local experts estimate that there are about 1 to 3
harbor seals in Tongass Narrows every day, in addition to those that
congregate near the seafood processing plants and fish hatcheries. NMFS
has indicated that the maximum group size in Tongass Narrows is three
individuals (83 FR 22009; May 11, 2018); however, ADOT monitoring in
March 2021
[[Page 6005]]
observed several groups of up to 5 individuals. Based on this
knowledge, the expected maximum group size in Tongass Narrows is five
individuals. Harbor seals are known to be curious and may approach
novel activity. For these reasons ADOT conservatively estimates that up
to two groups of 5 harbor seals per group could be taken by Level B
harassment due to project-related underwater noise each construction
day for a total of 910 takes by Level B harassment of harbor seal in
Tongass Narrows (i.e., 2 groups of 5 harbor seals per day x 91
construction days = 910 total takes by Level B harassment of harbor
seal; Table 15).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, Level B harassment zones would extend into Clarence Strait.
Harbor seals are known to swim across Clarence Strait, although no
estimates of at-sea density or abundance in Clarence Strait are
available. It is likely that harbor seal abundance in Clarence Strait
is lower than in Tongass Narrows, as harbor seals generally prefer
nearshore waters. Therefore, ADOT has conservatively estimated, and
NMFS concurs, that during the 44 days with potential simultaneous use
of two hammers, a group of 5 harbor seals may occur in the portion of
the Level B harassment zone in Clarence Strait each day (one group of 5
harbor seals per day x 44 days = 220 individuals). Therefore, the sum
of total estimated takes by Level B harassment of harbor seals between
Tongass Narrows and Clarence Strait is 1,130 (910 + 220 = 1,130 takes
by Level B harassment).
The largest Level A harassment zone for harbor seals could extend
1,918 m from the noise source for 10 hours of DTH using a single
hammer, or 1,640 m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types would occur on
no more than 44 days). Zones for shorter durations and other activities
would be smaller (Table 13). Due to practicability concerns, NMFS
proposes to require a 200 m shutdown zone for harbor seals during 24-in
and 30-in DTH activities (Table 16). Therefore, for some DTH
activities, the estimated Level A harassment zone is larger than the
proposed shutdown zone, and therefore, some Level A harassment could
occur. Harbor seals may enter and remain within the area between the
Level A harassment zone and the shutdown zone for a duration long
enough to be taken by Level A harassment. Additionally, while unlikely,
it is possible that a harbor seal could enter a shutdown zone without
detection given the various obstructions along the shoreline, and
remain in the zone for a duration long enough to be taken by Level A
harassment before being observed and a shutdown occurring.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (1,918 m-200 m shutdown
zone = 1,718 m) to the Level B harassment zone isopleth (13,594 m;
1,718 m/13,594 m = 0.1264). ADOT multiplied the resulting ratio by the
total potential take in Tongass Narrows, resulting in 116 takes by
Level A harassment (i.e., 910 takes by Level B harassment x 0.1264 =
116 takes by Level A harassment). NMFS reviewed, and concurs with and
adopts this method. (Potential operation of two DTH hammers for 24-in/
30-in or 30-in/30-in pile combinations would result in larger Level A
harassment isopleths than 1,918 m, however, such concurrent work would
rarely occur, if at all, and therefore, NMFS expects that calculating
Level A harassment take using those zones would be overly conservative
and unrealistic. Moreover, since the method used above assumes 30-inch
DTH on all days it provided a precautionary cushion since activities
with smaller Level A harassment zone sizes will occur on many days.)
Take by Level B harassment proposed for authorization was calculated as
the total calculated harbor seal takes by Level B harassment minus the
takes by Level A harassment (1,130 takes-116 takes by Level A
harassment) for a total of 1,014 takes by Level B harassment. ADOT
therefore requests, and NMFS proposes to authorize, 116 takes of harbor
seal by Level A harassment and 1,014 takes of harbor seal by Level B
harassment (1,130 total takes of harbor seal, Table 15).
Harbor Porpoise
Harbor porpoises are non-migratory; therefore, our occurrence
estimates are not dependent on season. Freitag (2017 as cited in 83 FR
37473; August 1, 2018) observed harbor porpoises in Tongass Narrows
zero to one time per month. Harbor porpoises observed in the project
vicinity typically occur in groups of one to five animals with an
estimated maximum group size of eight animals (83 FR 37473, August 1,
2018, Solstice 2018). ADOT's 2020 and 2021 monitoring program in
Tongass Narrows did not result in sightings of this species; however,
ADOT assumes an occurrence rate of one group per month in the following
take estimations. For our analysis, we are considering a group to
consist of five animals. Based on Freitag (2017), and supported by the
reports of knowledgeable locals as described in ADOT's application,
ADOT estimates that one group of five harbor porpoises could enter
Tongass Narrows and potentially taken by Level B harassment due to
project-related noise each month for a total of 15 potential harbor
porpoise takes by Level B harassment in Tongass Narrows (i.e., 1 group
of 5 individuals x 3 months (91 days) = 15 harbor porpoises).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone would extend into Clarence
Strait. Harbor porpoises are known to swim across Clarence Strait and
to use other areas of deep, open waters. Dahlheim et al. (2015)
estimated a density of 0.02 harbor porpoises/km\2\ in an area that
encompasses Clarence Strait. ADOT estimates, and NMFS concurs that
during the 44 days with potential simultaneous use of two hammers, 17
harbor porpoises (0.02 harbor porpoises/km\2\ x 18.5 km\2\ x 44 days =
17 harbor porpoises) may occur in the portion of the Level B harassment
zone in Clarence Strait during the project (though ADOT and NMFS
anticipate that this is a conservative estimate, given the entire 18.5
km\2\ area would rarely be ensonified above the Level B harassment
threshold). Therefore, the sum of total estimated takes by Level B
harassment of harbor porpoise between Tongass Narrows and Clarence
Strait is 32 (15 + 17 = 32 takes by Level B harassment).
The largest Level A harassment zone for harbor porpoises extends
4,269 m from the noise source for 10 hours of DTH using a single
hammer, and 3,673 m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types would occur on
no more than 44 days). Zones for shorter durations and other activities
would be smaller (Table 13). Due to practicability concerns, NMFS
proposes to require a 500 m shutdown zone for high frequency cetaceans
during 24-in and 30-in DTH activities. Therefore, for some DTH
activities, the estimated Level A harassment zone is larger than the
proposed shutdown zone, and therefore, some Level A harassment could
occur. Harbor porpoises may enter and remain within the area between
the Level A harassment zone
[[Page 6006]]
and the shutdown zone for a duration long enough to be taken by Level A
harassment. Additionally, given the large size of required shutdown
zones for some activities and the cryptic nature of harbor porpoises,
it is possible that a harbor porpoise could enter a shutdown zone
without detection and remain in the zone for a duration long enough to
be taken by Level A harassment before being observed and a shutdown
occurring.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (4,269 m-500 m = 3,769
m) to the Level B harassment zone isopleth (13,594 m; 3,769/13,594 =
0.2773). ADOT multiplied the resulting ratio by the total potential
take in Tongass Narrows, resulting in 5 takes by Level A harassment
(i.e., 15 takes by Level B harassment x 0.2773 = 5 takes by Level A
harassment). NMFS reviewed and concurs with this method. (Potential
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile
combinations would result in larger Level A harassment isopleths than
4,269 m, however, such concurrent work would rarely occur, if at all,
and therefore, as described above, NMFS expects that calculating Level
A harassment take using those zones is unnecessary.) Take by Level B
harassment proposed for authorization was calculated as the total
calculated harbor porpoise takes by Level B harassment minus the takes
by Level A harassment (32 takes-5 takes by Level A harassment) for a
total of 27 takes by Level B harassment. ADOT therefore requests and
NMFS proposes to authorize 5 takes by Level A harassment and 27 takes
by Level B harassment (32 total takes of harbor porpoise, Table 15).
Dall's Porpoise
Dall's porpoises are expected to only occur in the project area a
few times per year. Their relative rarity is supported by Jefferson et
al.'s (2019) presentation of historical survey data showing very few
sightings in the Ketchikan area and conclusion that Dall's porpoise
generally are rare in narrow waterways, like the Tongass Narrows.
ADOT's monitoring program from 2020 and 2021 recorded one sighting of 6
individuals over 23 days of observation, 16 days of observations with
no sightings, and two sightings of 10 individuals in 14 days of
observation; this equates to one sighting every approximately 17 days
(DOT&PF 2020, 2021a, 2021b, 2021c, 2021d) or approximately two
sightings per month. This species is non-migratory; therefore, the
occurrence estimates are not dependent on season. ADOT anticipates that
one large Dall's porpoise pod (12 individuals) may be present in the
project area and exposed to project related underwater noise twice each
month during 3 months of construction (91 days rounded to 3 months) for
a total of 72 potential takes by Level B harassment in Tongass Narrows
(i.e.,2 groups of 12 Dall's porpoises per month x 3 months = 72
potential takes by Level B harassment).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone would extend into Clarence
Strait, where Dall's porpoises are known to occur. Jefferson et al.
(2019) estimated an average density of 0.19 Dall's porpoises/km\2\ in
Southeast Alaska. ADOT estimates, and NMFS concurs, that during the 44
days with potential simultaneous use of two hammers, 155 Dall's
porpoises (0.19 Dall's porpoises/km\2\ x 18.5 km\2\ x 44 days = 155
Dall's porpoises) may occur in the portion of the Level B harassment
zone in Clarence Strait during the project (though ADOT and NMFS
anticipate that this is a conservative estimate, given the entire 18.5
km\2\ area would rarely be ensonified above the Level B harassment
threshold). Therefore, the sum of total estimated takes by Level B
harassment of harbor porpoise between Tongass Narrows and Clarence
Strait is 227 (72 + 155 = 227 takes by Level B harassment).
The largest Level A harassment zone for Dall's porpoises extends
4,269 m from the noise source for 10 hours of DTH using a single
hammer, and m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types would occur on
no more than 44 days). Zones for shorter durations and other activities
would be smaller (Table 13). Due to practicability concerns, NMFS
proposes to require a 500 m shutdown zone for high frequency cetaceans
during 24-in and 30-in DTH activities. Therefore, for some DTH
activities, the estimated Level A harassment zone is larger than the
proposed shutdown zone, and therefore, some Level A harassment could
occur. Dall's porpoises may enter and remain within the area between
the Level A harassment zone and the shutdown zone and be exposed to
sound levels for a duration long enough to be taken by Level A
harassment. Additionally, given the large size of the required shutdown
zones for some activities, it is possible that a Dall's porpoise could
enter a shutdown zone without detection and remain in the zone for a
duration long enough to taken by Level A harassment before being
observed and a shutdown occurring.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (4,269 m-500 m = 3,769
m) to the Level B harassment zone isopleth (13,594 m; 3,769/13,594 =
0.2773). ADOT multiplied the resulting ratio by the total potential
take in Tongass Narrows, resulting in 20 takes by Level A harassment
(i.e., 72 takes by Level B harassment x 0.2773 = 20 takes by Level A
harassment). NMFS revised and concurs with this method. (Potential
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile
combinations would result in larger Level A harassment isopleths than
4,269 m, however, such concurrent work would rarely occur, if at all,
and therefore, as described above, NMFS expects that calculating Level
A harassment take using those zones is unnecessary.) Take by Level B
harassment proposed for authorization was calculated as the total
calculated Dall's porpoise takes by Level B harassment minus the takes
by Level A harassment (227 takes-20 takes by Level A harassment) for a
total of 207 takes by Level B harassment. ADOT therefore requests and
NMFS proposes to authorize 20 takes by Level A harassment, and 207
takes by Level B harassment (227 total takes of Dall's porpoise, Table
15).
Pacific White-Sided Dolphin
Pacific white-sided dolphins do not generally occur in the shallow,
inland waterways of Southeast Alaska. There are no records of this
species occurring in Tongass Narrows, and it is uncommon for
individuals to occur in the proposed project area. However, historical
sightings in nearby areas (Dahlheim and Towell 1994; Muto et al. 2018)
and recent fluctuations in distribution and abundance mean it is
possible the species could be present.
To account for the possibility that this species could be present
in the project area, ADOT conservatively estimates, and NMFS concurs,
that one large group (92 individuals) of Pacific white-sided dolphins
may be taken by Level B harassment in Tongass Narrows during the
proposed activity.
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone would
[[Page 6007]]
extend into Clarence Strait. However, no additional takes of Pacific
white-sided dolphin are anticipated to occur due to simultaneous use of
two hammers, given that Pacific white-sided dolphins are uncommon in
the project area. Therefore, NMFS is proposing to authorize 92 takes by
Level B harassment of Pacific white-sided dolphins.
ADOT did not request, nor does NMFS propose to authorize take by
Level A harassment for this activity given that Pacific white-sided
dolphins are uncommon in the project area. Further, considering the
small Level A harassment zones for mid-frequency cetaceans (Table 13
and Table 14) in comparison to the required shutdown zones, it is
unlikely that a Pacific white-sided dolphin would enter and remain
within the area between the Level A harassment zone and the shutdown
zone for a duration long enough to be taken by Level A harassment.
Killer Whale
Killer whales are observed in Tongass Narrows irregularly with
peaks in abundance between May and July. During 7 months of
intermittent marine mammal monitoring (October 2020-February 2021; May-
June 2021), there were five killer whale sightings in 4 months
(November, February, May, June) totaling 22 animals; sightings occurred
on 5 out of 88 days of monitoring (DOT&PF 2020, 2021a, 2021b, 2021c,
2021d). Pod sizes ranged from two to eight animals (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). Previous incidental take authorizations in the
Ketchikan area have estimated killer whale occurrence in Tongass
Narrows at one pod per month, except during the peak period of May to
July when estimates have included two pods per month (Freitag 2017 as
cited in 83 FR 37473; August 1, 2018 and 83 FR 34134; July 17, 2019).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone would extend into Clarence
Strait. In estimating take by Level B harassment, ADOT assumed a pod
size of 12 killer whales, that all 91 days of work would occur between
May and July during the peaks in abundance, and that therefore, 2 pods
may occur within the Level B harassment zone (including both Tongass
Narrows and Clarence Strait) during each month of work, for a total of
72 takes by Level B harassment (2 groups x 12 individuals x 3 months =
72 killer whales). Therefore, ADOT estimates that a total of 72 killer
whales may be taken by Level B harassment (i.e., 2 pods of 12
individuals per month x 3 months (91 days) = 72 takes by Level B
harassment). NMFS reviewed and concurs with this method, and proposes
to authorize 72 takes by Level B harassment of killer whale.
ADOT did not request, nor does NMFS propose to authorize take by
Level A harassment of killer whales for this activity. Considering the
small Level A harassment zones for mid-frequency cetaceans (Table 13
and Table 14) in comparison to the required shutdown zones, it is
unlikely that a killer whale would enter and remain within the area
between the Level A harassment zone and the shutdown zone for a
duration long enough to be taken by Level A harassment.
Humpback Whale
As discussed in the Description of Marine Mammals in the Area of
Specified Activities section, locals have observed humpback whales an
average of about once per week in Tongass Narrows, but there is
evidence to suggest occurrence may be higher during some periods of the
year. The December 19, 2019 Biological Opinion stated that based on
observations by local experts, approximately one group of two
individuals would occur in Tongass Narrows during ADOT's activity two
times per seven days during pile driving, pile removal, and DTH
activities throughout the year. The assumption was based on differences
in abundance throughout the year, recent observations of larger groups
of whales present during summer, and a higher than average frequency of
occurrence in recent months (NMFS 2019). ADOT's 2020 and 2021
monitoring program documented a similar sighting rate, with 30 humpback
whale sightings over 53 days of in-water pile driving; some of the
sightings were believed to be repeated sightings of the same individual
(DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). ADOT therefore predicts, and
NMFS concurs, that one group of two individuals may occur within the
Level B harassment zones twice per week during the proposed activities.
As noted previously, ADOT estimates that pile driving would occur over
the course of 91 days (13 weeks). Therefore, ADOT estimates, and NMFS
concurs that 52 takes by Level B harassment of humpback whales (1 group
of 2 individuals x 2 groups per week x 13 weeks = 52 takes by Level B
harassment) from the Central North Pacific stock may occur in Tongass
Narrows.
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone would extend into Clarence
Strait. Local specialists estimated that approximately four humpback
whales could pass through or near the portion of the Level B harassment
zone in Clarence Strait each day. Therefore, ADOT estimates, and NMFS
concurs, that during the 44 days with potential simultaneous use of two
hammers, 176 takes by Level B harassment of humpback whale could occur
in Clarence Strait (4 humpback whales x 44 days = 176 takes by Level B
harassment). Therefore, the sum of total estimated takes by Level B
harassment of humpback whale between Tongass Narrows and Clarence
Strait is 228 (52 + 176 = 228 takes by Level B harassment), and NMFS
proposes to authorize 228 takes by Level B harassment of humpback
whale.
As noted previously, Wade et al. (2021) estimates that
approximately 2 percent of all humpback whales in Southeast Alaska and
northern British Columbia are of the Mexico DPS, while all others are
of the Hawaii DPS. However, NMFS has conservatively assumed here that
6.1 percent of the total humpback population in Southeast Alaska is
from the Mexico DPS (Wade et al. 2016). Therefore, of the 228 takes of
humpback whale proposed for authorization, NMFS expects that a total of
14 takes would be of individuals from the Mexico DPS. NMFS expects that
all other instances of proposed take would be from the non-listed
Hawaii DPS.
Take by Level A harassment of humpback whales is neither
anticipated nor proposed to be authorized because of the expected
effectiveness of the required monitoring and mitigation measures (see
Proposed Mitigation section below for more details). For all pile
driving and DTH activities, the shutdown zone exceeds the calculated
Level A harassment zone. Humpbacks are usually readily visible, and
therefore, we expect PSOs to be able to effectively implement the
required shutdown measures prior to any humpback whales incurring PTS
within Level A harassment zones.
Minke Whales
Minke whales may be present in Tongass Narrows year-round. Their
abundance throughout Southeast Alaska is very low, and anecdotal
reports have not included minke whales near the project area. ADOT's
monitoring program in Tongass Narrows also did not report any minke
whale sightings. However, minke whales are distributed throughout a
wide variety of habitats and could occur near the project area.
[[Page 6008]]
Minke whales are generally sighted as solo individuals (Dahlheim et al.
2009).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone would extend into Clarence
Strait. Based on Freitag (2017; as cited in 83 FR 37473; August 1, 2018
and 83 FR 34134; July 17, 2019), ADOT estimates that three individual
minke whales may occur near or within the Level B harassment zone
(including both Tongass Narrows and Clarence Strait) every four months.
Based on that estimated occurrence rate, NMFS estimates that three
minke whales may occur in the Level B harassment zone during the
proposed activities (occurring over approximately 3 months), and
proposes to authorize 3 takes by Level B harassment of minke whales
(Table 15).
The largest Level A harassment zone for minke whale extends 3,584 m
from the noise source for 10 hours of DTH using a single hammer, and
3,084 m from the noise source for 4 hours of DTH using two hammers for
30-in piles simultaneously. (As noted previously, ADOT estimates that
simultaneous use of any two hammer types would occur on no more than 44
days.) Zones for shorter durations and other activities would be
smaller (Table 14). NMFS proposes to require a 1,500 m shutdown zone
for minke whales during 24-in and 30-in DTH activities. Therefore, for
some DTH activities, the estimated Level A harassment zone is larger
than the proposed shutdown zone, and Level A harassment could occur.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (3,584 m-1,500 m = 2,084
m) to the Level B harassment zone isopleth (13,594 m; 2,084 m/13,594 m
= 0.1533). ADOT multiplied the resulting ratio by the total potential
take by Level B harassment, resulting in 1 take by Level A harassment
(i.e., 3 takes by Level B harassment x 0.1533 = 1 take by Level A
harassment). NMFS reviewed and concurs with this method. (Potential
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile
combinations would result in larger Level A harassment isopleths than
4,269 m, however, such concurrent work would rarely occur, if at all,
and therefore, as described above NMFS expects that calculating Level A
harassment take using those zones is unnecessary.) Take by Level B
harassment was calculated as the total potential minke whale takes by
Level B harassment minus the takes by Level A harassment. ADOT
therefore requests, and NMFS proposes to authorize 1 take by Level A
harassment and 2 takes by Level B harassment (3 total takes of minke
whale, Table 15).
Table 15--Proposed Amount of Take as a Percentage of Stock Abundance, by Stock and Harassment Type
----------------------------------------------------------------------------------------------------------------
Proposed authorized take
------------------------------------------------ Percent of
Species DPS/stock Level A Level B stock
harassment harassment Total
----------------------------------------------------------------------------------------------------------------
Steller sea lion.............. Eastern U.S..... 91 2,169 2,260 5.2
Harbor seal................... Clarence Strait. 116 1,014 1,130 4.1
Harbor porpoise............... Southeast Alaska 5 27 32 2.5
Dall's porpoise............... Alaska.......... 20 207 227 1.7
Pacific white-sided dolphin... North Pacific... 0 92 92 0.3
Killer whale.................. Alaska Resident. .............. .............. .............. \a\ 3.1
West Coast 0 72 72 \a\ 20.1
Transient.
Northern .............. .............. .............. \a\ 23.8
Resident.
Humpback whale................ Central North 0 228 228 \b\ 2.3
Pacific.
Minke whale................... Alaska.......... 1 2 3 N/A
----------------------------------------------------------------------------------------------------------------
Proposed Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses. NMFS regulations require applicants for incidental
take authorizations to include information about the availability and
feasibility (economic and technological) of equipment, methods, and
manner of conducting the activity or other means of effecting the least
practicable adverse impact upon the affected species or stocks and
their habitat (50 CFR 216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, 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.
Because of the need for an ESA Section 7 consultation for effects
of the project on ESA listed humpback whales, there are a number of
mitigation measures that go beyond, or are in addition to, typical
mitigation measures we would otherwise require for this sort of
project. The proposed measures are however typical for actions in the
Ketchikan area. The mitigation measures included herein include
measures that align with the 2019 Biological Opinion, and are subject
to change, as required by NMFS' ESA Section 7 consultation. If Section
7 consultation warrants changes to these measures, NMFS expects that
the new measures would align closely with those included in the recent
proposed IHA for construction at the NOAA Port Facility
[[Page 6009]]
Project in Ketchikan, Alaska (86 FR 68223; December 1, 2021). ADOT must
employ the following mitigation measures as included in the proposed
IHA:
<bullet> 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 (note that NMFS expects that a 10 m shutdown zone is
sufficient to avoid direct physical interaction with marine mammals,
but ADOT has conservatively proposed a 20 m shutdown zone to avoid
physical interaction for in-water other than vessel transit);
<bullet> Ensure that construction supervisors and crews, the
monitoring team and relevant ADOT staff are trained prior to the start
of all pile driving and DTH activity, so that responsibilities,
communication procedures, monitoring protocols, and operational
procedures are clearly understood. New personnel joining during the
project must be trained prior to commencing work;
<bullet> Pile driving activity must be halted upon observation of
either a species for which incidental take is not authorized or a
species for which incidental take has been authorized but the
authorized number of takes has been met, entering or within the
harassment zone;
<bullet> For any marine mammal species for which take by Level B
harassment has not been requested or authorized, in-water pile
installation/removal and DTH will shut down immediately when the
animals are sighted;
<bullet> Employ PSOs and establish monitoring locations as
described in the Marine Mammal Monitoring Plan and Section 5 of the
IHA. The Holder must monitor the project area to the maximum extent
possible based on the required number of PSOs, required monitoring
locations, and environmental conditions. For all pile driving and
removal at least three PSOs must be used;
<bullet> The placement of the PSOs during all pile driving and
removal and DTH activities will ensure that the entire shutdown zone is
visible during pile installation;
<bullet> Monitoring must take place from 30 minutes prior to
initiation of pile driving or DTH activity (i.e., pre-clearance
monitoring) through 30 minutes post-completion of pile driving or DTH
activity;
<bullet> If in-water work ceases for more than 30 minutes, ADOT
will conduct pre-clearance monitoring of both the Level B harassment
zone and shutdown zone;
<bullet> Pre-start clearance monitoring must be conducted during
periods of visibility sufficient for the lead PSO to determine that the
shutdown zones indicated in Table 16 are clear of marine mammals. Pile
driving may commence following 30 minutes of observation when the
determination is made that the shutdown zones are clear of marine
mammals;
<bullet> If a marine mammal is observed entering or within the
shutdown zones indicated in Table 16, pile driving must be delayed or
halted. If pile driving is delayed or halted due to the presence of a
marine mammal, the activity may not commence or resume until either the
animal has voluntarily exited and been visually confirmed beyond the
shutdown zone (Table 16) or 15 minutes have passed without re-detection
of the animal (30 minutes for humpback whales);
<bullet> As required by the 2019 Biological Opinion, if waters
exceed a sea state that restricts the PSOs' ability to make
observations within the shutdown zone, in-water pile installation and
removal will cease. Pile installation and removal will not be initiated
or continue until the appropriate shutdown zone is visible in its
entirety;
<bullet> For humpback whales, if the boundaries of the harassment
zone have not been monitored continuously during a work stoppage, the
entire harassment zone will be surveyed again to ensure that no
humpback whales have entered the harassment zone that were not
previously accounted for;
<bullet> In-water activities will take place only: Between civil
dawn and civil dusk when PSOs can effectively monitor for the presence
of marine mammals; during conditions with a Beaufort Sea State of 4 or
less; when the entire shutdown zone and adjacent waters are visible
(e.g., monitoring effectiveness is not reduced due to rain, fog, snow,
etc.). Pile driving may continue for up to 30 minutes after sunset
during evening civil twilight, as necessary to secure a pile for safety
prior to demobilization for the evening. PSO(s) will continue to
observe shutdown and monitoring zones during this time. The length of
the post- activity monitoring period may be reduced if darkness
precludes visibility of the shutdown and monitoring zones;
<bullet> Vessel operators will implement the following required
measures: Maintain a watch for marine mammals at all times while
underway; remain at least and at least 91 m (100 yards (yd)) from all
other listed marine mammals, travel at less than 5 knots (9 km/hr) when
within 274 m (300 yd) of a whale; avoid changes in direction and speed
when within 274 m (300 yd) of whales, unless doing so is necessary for
maritime safety; not position vessel(s) in the path of whales, and will
not cut in front of whales in a way or at a distance that causes the
whales to change their direction of travel or behavior (including
breathing/surfacing pattern); check the waters immediately adjacent to
the vessel(s) to ensure that no whales will be injured when the
propellers are engaged; adhere to the Alaska Humpback Whale Approach
Regulations when transiting to and from the project site (see 50 CFR
216.18, 223.214, and 224.103(b)); not allow lines to remain in the
water, and not throw trash or other debris overboard, thereby reducing
the potential for marine mammal entanglement; follow established
transit routes and travel <10 knots while in the harassment zones;
follow the speed limit within Tongass Narrows (7 knots for vessels over
23 ft in length). If a whale's course and speed are such that it will
likely cross in front of a vessel that is underway, or approach within
91 m (100 yards (yd)) of the vessel, and if maritime conditions safely
allow, the engine will be put in neutral and the whale will be allowed
to pass beyond the vessel, except that vessels will remain 460 m (500
yd) from North Pacific right whales; if a humpback whale comes within
10 m (32.8 ft) of a vessel during construction, the vessel will reduce
speed to the minimum level required to maintain safe steerage and
working conditions until the humpback whale is at least 10 m (32.8 ft)
away from the vessel; vessels are prohibited from disrupting the normal
behavior or prior activity of a whale by any other act or omission.
<bullet> ADOT must use soft start techniques when impact pile
driving. Soft start requires contractors to provide an initial set of
three strikes at reduced energy, followed by a 30-second waiting
period, then two subsequent reduced-energy strike sets. A soft sta
[…truncated; see source link]Indexed from Federal Register on February 2, 2022.
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.