Notice2022-23775
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Relocation of National Oceanic and Atmospheric Administration Research Vessels at Naval Station Newport, Rhode Island
Primary source
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Published
November 2, 2022
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the U.S. Navy on behalf of NOAA Office of Marine and Aviation Operations (OMAO) for authorization to take marine mammals incidental to construction activities associated with the relocation of NOAA research vessels at Naval Station Newport in Rhode Island. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, 1-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 authorization and agency responses will be summarized in the final notice of our decision.
Full Text
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<title>Federal Register, Volume 87 Issue 211 (Wednesday, November 2, 2022)</title>
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[Federal Register Volume 87, Number 211 (Wednesday, November 2, 2022)]
[Notices]
[Pages 66133-66161]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-23775]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XC247]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Relocation of National Oceanic and
Atmospheric Administration Research Vessels at Naval Station Newport,
Rhode Island
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from the U.S. Navy on behalf of
NOAA Office of Marine and Aviation Operations (OMAO) for authorization
to take marine mammals incidental to construction activities associated
with the relocation of NOAA research vessels at Naval Station Newport
in Rhode Island. Pursuant to the Marine Mammal Protection Act (MMPA),
NMFS is requesting comments on its proposal to issue an incidental
harassment authorization (IHA) to incidentally take marine mammals
during the specified activities. NMFS is also requesting comments on a
possible one-time, 1-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 authorization and agency responses will be
summarized in the final notice of our decision.
DATES: Comments and information must be received no later than December
2, 2022.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service and should be submitted via email to
<a href="/cdn-cgi/l/email-protection#bff6ebef91cbdec6d3d0cdffd1d0dede91d8d0c9"><span class="__cf_email__" data-cfemail="f9b0ada9d78d988095968bb997969898d79e968f">[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 would 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: Jessica Taylor, 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/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</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 proposed or, if the taking is limited to harassment, a notice of a
proposed incidental harassment authorization is provided to the public
for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of the takings are set forth. The definitions
of all applicable MMPA statutory terms cited above are included in the
relevant sections below.
[[Page 66134]]
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 May 6, 2022, NMFS received a request from the U.S. Navy on
behalf of OMAO for an IHA to take marine mammals incidental to
construction activities associated with the relocation of NOAA research
vessels to the Naval Station Newport in Rhode Island. NMFS reviewed the
Navy's application and the Navy provided a revised application on July
14, 2022. The application was deemed adequate and complete on October
5, 2022. OMAO's request is for take of 7 species of marine mammals, by
Level B harassment and, for a subset of these species, Level A
harassment. Neither OMAO nor NMFS expect serious injury or mortality to
result from this activity and, therefore, an IHA is appropriate. OMAO
plans to commence in-water construction activities on February 1, 2024
yet has requested the IHA in advance due to OMAO's NEPA requirements.
Description of Proposed Activity
Overview
OMAO proposes to establish adequate pier, shore side, and support
facilities for four NOAA research vessels in Coddington Cove at Naval
Station (NAVSTA) Newport in Newport, Rhode Island. As part of the
proposed activity, a new pier, trestle, small boat floating dock, and
bulkhead would be constructed in Coddington Cove in order to meet NOAA
docking/berthing requirements for these four vessels. These
construction activities would involve the use of impact and vibratory
pile driving, vibratory pile extraction, rotary drilling, and down-the-
hole (DTH) mono-hammer excavation events, which have the potential to
take marine mammals, by Level A and Level B harassment. The project
would also include shore side administrative, warehouse, and other
support facilities.
Currently two of the four Rhode Island NOAA research vessels are
located at Pier 2 at NAVSTA Newport; however, Pier 2 does not provide
adequate docking and berthing for these vessels to meet NOAA
requirements. The two other NOAA Atlantic Fleet vessels are located in
New Hampshire, Virginia, South Carolina, or Mississippi. As many of the
NOAA research cruises are conducted in the northeast, relocating four
vessels to the project area provides logistical advantages and
operational efficiencies.
Coddington Cove, which opens to Narragansett Bay, covers an area of
approximately 395 acres (1.6 square kilometers) and is located near the
southeast corner of NAVSTA Newport. Construction activities would last
for approximately 1 year from February 1, 2024 to January 31, 2025 of
which in-water work would take place over 343 non-consecutive days.
Dates and Duration
In-water construction activities are estimated to occur over 343
non-consecutive days from February 1, 2024 to January 31, 2025. OMAO
anticipates that all work would be limited to daylight hours. Specific
construction activities may occur concurrently over a period of
approximately 138 days. Table 1 provides a summary of proposed
scenarios in which equipment may be used concurrently.
Table 1--Summary of Multiple Equipment Scenarios
----------------------------------------------------------------------------------------------------------------
Structure Activity Equipment and quantity
----------------------------------------------------------------------------------------------------------------
Bulkhead............................. Template installation (16- Vibratory Hammer (2).
inch steel) and steel pipe Vibratory Hammer (1), Impact Hammer (1).
pile installation (18-inch).
Vibratory Hammer (2), DTH Mono-hammer (1).
----------------------------------------------------------------------------------------------------------------
Bulkhead and Trestle................. Template extraction from Vibratory Hammer (3).
Bulkhead (16-inch steel), Vibratory Hammer (1), Impact Hammer (1),
Install sheet piles Bulkhead Rotary Drill (1).
(Z26-700), Install steel
pipe piles at Trestle (18-
inch).
Vibratory Hammer (2), Impact Hammer (1),
Rotary Drill (1).
----------------------------------------------------------------------------------------------------------------
Pier................................. Template Install (16-inch Vibratory Hammer (2).
steel) and Install steel Vibratory Hammer (1), Impact Hammer (1)
pipe piles (30-inch) at Pier.
Vibratory Hammer (1), Impact Hammer (1),
Rotary Drill (1).
----------------------------------------------------------------------------------------------------------------
Pier fender piles, gangway, and Install pipe piles (16-inch) Vibratory Hammer (2)
floating dock. at Pier and install steel Vibratory Hammer (1), Impact Hammer (1).
pipe piles at Small Boat
Floating Dock (18-Inch).
[[Page 66135]]
Template Extraction from Pier Vibratory Hammer (2), Impact Hammer (1).
(16-inch steel) and install Vibratory Hammer (1), Impact Hammer (1).
shafts (36-inch) at Small
Boat Floating Dock.
Vibratory (2), DTH Mono-hammer (1).
----------------------------------------------------------------------------------------------------------------
Specific Geographic Region
NAVSTA Newport encompasses 1,399 acres (5.66 (square kilometers)
km\2\) extending 6-7 miles (9.7-11.3 kilometers (km)) along the western
shore of Aquidneck Island in the towns of Portsmouth and Middletown,
Rhode Island and the city of Newport, Rhode Island. The base footprint
also includes the northern third of Gould Island in the town of
Jamestown, Rhode Island. The base is located in the southern part of
the state where Narragansett Bay adjoins the Atlantic Ocean. Figure 1
shows the site of where the proposed action would occur in Coddington
Cove.
Coddington Cove covers an area of approximately 395 acres (1.6
km\2\) and is partially protected by Coddington Point to the south and
a breakwater to the north. The northwest section of the cove opens to
Narragansett Bay. Water depths in the proposed project area of
Coddington Cove are less than 34 ft (10.4 m) mean lower low water. The
proposed project area experiences semi-diurnal tides, an average water
temperature of 36-68 [deg]F (2.2-20 [deg]C), and salinity of 31 parts
per thousand. Narragansett Bay is approximately 22 nautical miles (nm)
(40 km) long and 7 nm (16 km) wide. Narragansett Bay's most prominent
bathymetric feature is a submarine valley that runs between Conanicut
and Aquidneck Islands to Rhode Island Sound, and defines the East
Passage of Narragansett Bay. The shipping channel in the East Passage
serves as the primary shipping channel for the rest of Narragansett Bay
and is generally 100 ft (30.5 m) deep. The shipping channel from the
lower East Passage splits just south of Gould Island with the western
shipping channel heading to Quonset Point and the eastern shipping
channel heading to Providence and Fall River (Navy, 2008). Vessel noise
from commercial shipping and recreational activities contribute to the
ambient underwater soundscape in the proposed project area. Based upon
underwater noise data collected at the Naval Undersea Warfare Center
(NUWC) and the shallow depth of nearshore water, the ambient underwater
noise in the proposed project area is expected to be approximately 120
dB RMS.
BILLING CODE 3510-22-P
[[Page 66136]]
[GRAPHIC] [TIFF OMITTED] TN02NO22.000
BILLING CODE 3510-22-C
Figure 1. Proposed NAVSTA Project Area
Detailed Description of the Specified Activity
The proposed activity would establish adequate pier, shore side,
and support facilities to support the relocation of four NOAA Atlantic
Fleet research vessels at NAVSTA Newport, RI. This includes the
construction of a new pier, trestle, small boat floating dock,
bulkhead, and shore side facilities in Coddington Cove for which the
in-water schedule is shown in Table 2. Upland construction at the Pier
landing and parking facilities near Building 11 (Figure 1) would not
involve any in-water work and is not expected to result in any takes of
marine mammals; these activities are therefore not further discussed.
Table 2--Proposed In-Water Work Schedule
--------------------------------------------------------------------------------------------------------------------------------------------------------
Minutes to
drive/ Number of
Construction Pile type and Method of pile Daily extract/ impact Total
Facility period diameter (in) Number of piles driving/ production rate drill a strikes/ production
extraction single pile days \1\
pile
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abandoned guide piles along February 2024... 12'' steel...... 3.............. Vibratory 3 piles/day.... 30 N/A 1
bulkhead. extraction.
Floating dock demolition..... February 2024... 12'' timber..... 4.............. Vibratory 4 piles/day.... 30 N/A 1
extraction.
Bulkhead Construction........ February-April 18'' steel...... 115............ Vibratory/ 8 piles/day.... 30 1,000 15
2024. impact.
[[Page 66137]]
12............. DTH Mono-hammer 1 hole/day..... 300 13 12
\2\ \3\.
Steel sheet pile 230 (115 pairs) Vibratory...... 8 pairs/day.... 30 N/A 15
Z26-700, 18''
deep.
16 template 60 (4x 15 Vibratory 4 piles/day.... 30 N/A 30
steel pile. moves). installation/
extraction.
Trestle...................... April-June 2024 18'' steel pipe 36............. Vibratory/ 2 piles/day.... 30 1,500 18
*. pile. impact.
bents 1-18................... 4.............. Rotary drilling 1 hole/day..... 300 N/A 4
\4\.
16'' template 72 (4x 18 Vibratory 4 piles/day.... 30 N/A 36
steel pipe pile. moves). installation/
extraction.
Trestle...................... June 2024....... 30'' steel pipe 2.............. Vibratory/ 2 piles/day.... 45 2,000 1
pile. impact.
bent 19...................... 16'' template 4 (4x 1 moves). Vibratory 4 piles/day.... 30 N/A 2
steel pipe pile. installation/
extraction.
Pier......................... June-December 30'' steel pipe 120............ Vibratory/ 4 piles/day.... 45 2,000 30
2024 **. pile. impact.
12............. Rotary drilling 1 hole/day..... 300 N/A 12
\4\.
16'' template 120 (4x 30 Vibratory 4 piles/day.... 30 N/A 60
steel pipe pile. moves). installation/
extraction.
Fender Piles................. September 2024- 16'' steel pipe 201............ Vibratory...... 4 piles/day.... 20 N/A 50
January 2025 **. pile.
16'' template 96 (4x 24 Vibratory 4 piles/day.... 30 N/A 48
steel pipe pile. moves). installation/
extraction.
Gangway support piles for January 2025 **. 18'' steel pipe 4.............. Vibratory/ 2 piles/day.... 30 1,000 2
small boat floating dock. piles. impact.
Small floating dock.......... January 2025 **. 36'' steel 2.............. Vibratory/ 1 pile/day..... 60 1,000 2
casing shaft impact.
with rock
socket (guide
pile).
2.............. DTH Mono-hammer 1 hole/day..... 300 13 strikes/ 2
\2\ \3\ \5\. second
16'' template 4 (4x 1 moves). Vibratory 4 piles/day.... 30 N/A 2
steel pipe pile. installation/
extraction.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Pile installation at Bulkhead and Trestle may be concurrent.
** Pile installation of Fender piles, Gangway, and Floating Dock may be concurrent.
\1\ Total production days for template piles includes the time to install and the time to extract the piles.
\2\ ``Down-the-hole'' (DTH) mono-hammer excavation may be used to clear boulders and other hard driving conditions for pipe piling at the bulkhead. DTH
mono-hammer would only be used when obstructions or refusal (hard driving) occurs that prevents the pile from being advanced to the required tip
elevation using vibratory/impact driving. The DTH mono-hammer is placed inside of the steel pipe pile and operates at the bottom of the hole to clear
through rock obstructions, hammer does not ``drive'' the pile but rather cleans the pile and removes obstructions such that the piles may be installed
to ``minimum'' tip elevation.
\3\ DTH mono-hammer uses both impulsive (strikes/second) and continuous methods (minutes).
\4\ Rotary drilling may be used to clear boulders/obstructions for trestle and pier. Core barrel would be lowered through the pile and advanced using
rotary methods to clear the obstruction. After the obstruction is cleared, the piling would be advanced to the required tip elevation using impact
driving methods.
\5\ DTH mono-hammer would be used to create a rock socket at each of the 36-inch shafts for the floating dock.
Pier and Trestle: A new pile supported concrete pier would be
constructed approximately 450 ft (137.1 m) north of the existing T-pier
in Coddington Cover (Figure 1). The new pier would be approximately 62
ft (18.9 m) wide and and 587 ft (178.9 m) long, encompassing an area of
36,400 square ft (ft\2\, 3,381.6 m\2\). Structural support piles for
the new pier would consist of 120 30'' steel pipe piles. These piles
would be driven by vibratory and impact hammers to a depth required to
achieve bearing capacity. A rotary drill may be used to clear any
obstructions, such as glacial boulders. Fender piles would be installed
and consist of 201 16'' diameter steel pipe piles.
In order to access the pier, a 28 ft (8.5 m) wide by 525 ft (160 m)
long pile-supported trestle would be constructed. The trestle would
cover an area of approximately 14,200 ft\2\ (1,319.2 m\2\) over the
water. The entrance to the trestle would be located upland and span
over two existing bulkheads, a sheet pile bulkhead, and a new bulkhead
connected to the pier. Structural support piles for the trestle
concrete deck would include 36 18'' steel pipe piles and 2 30'' steel
pipe piles. The piles would be driven by impact and vibratory hammers
to depths required to achieve bearing capacity. If construction crews
encounter obstructions, such as glacial boulders, a rotary drill may be
used.
Trestle and pier piles would be installed using a template that
would be secured by 4 16'' steel pipe piles. Once the pier or trestle
piles are installed in the template, the template would be removed and
relocated to the next section of the pier/trestle construction. The
template piles would be installed and removed by vibratory installation
and extraction. Use of the template would require the driving and
removal of the template piles approximately 19 times for the trestle
and 30 times for the pier, for a total of 196 installation/extraction
moves of the pipe piles.
Small Boat Floating Dock: A small boat floating dock would be
constructed northwest of the pier and trestle structure. The dock would
be approximately 20 ft (6.1 m) wide by 66 ft (20.1 m) long, and provide
berthing on two sides. The floating system would consist of a single
heavy duty 20 ft (6.1 m) by 66 ft (20.1 m) concrete float of
approximately 1,300 ft\2\ (120.8 m\2\) and two 5.5 ft (1.7 m) wide by
80 ft (24.3 m) long gangway segments of approximately 440 ft\2\ (40.9
m\2\) each. The gangway would be supported by 4 18'' steel pipe piles.
These piles would be driven by vibratory installation followed by
impact installation to achieve bearing capacity. Two 36'' steel pipe
guide piles would provide lateral support to the floating dock. The
guide piles would be rock socketed into the bedrock. Shafts would be
installed using vibratory and impact driving methods, then set into
rock socket anchors and filled with concrete. DTH excavation using a
mono-hammer would be used to
[[Page 66138]]
create the rock sockets. Additionally, an abandoned dock currently
exists at the proposed site of the floating dock. Demolition of the
abandoned dock involving the vibratory extraction of 3 12'' steel pipe
piles and 4 12'' timber piles would take place before the small boat
floating dock would be installed.
Bulkhead: In order to reinforce and stabilize an existing
deteriorating bulkhead, a new bulkhead of approximately 728 ft (221.9
m) in length would be constructed near the proposed new pier location.
A combination of approximately 115 18'' steel pipe piles and 230 steel
Z-shaped sheet piles (55'' long and 8'' deep) would be installed along
the face of the existing bulkhead using vibratory and impact driving.
If obstructions, such as solid bedrock, boulders, or debris are
encountered, pile installation may require the use of DTH mono-hammer
excavation to break up rock or moving the obstruction aside using
mechanical means. Piles would be installed using a template that would
be secured by 4 16'' steel pipe piles. The use of the template would
require the vibratory driving and extraction of the 4 template piles
approximately 15 times for a total of 60 installation/extraction moves
of the pipe template piles.
Pile installation and removal would occur using barge-mounted
cranes and land-based cranes equipped with vibratory and impact
hammers. Piles would initially be installed using vibratory methods,
then finished with impact hammers as necessary. Impact hammers would
also be used where obstructions or sediment conditions do not permit
the efficient use of vibratory hammers. Rotary drilling may be used to
clear obstructions during pile driving. DTH mono-hammer excavation
combines the use of rotary drilling and percussive hammering to
fracture rock. This method may also be used to clear obstructions in
addition to set piles in rock sockets. Piles would be driven using a
vibratory pile driver whenever possible in order to reduce impacts.
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. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, incorporated here by reference, instead of
reprinting the information. Additional information regarding population
trends and threats may be found in NMFS' Stock Assessment Reports
(SARs; <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">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' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 3 lists all species or stocks for which take is expected and
proposed to be authorized for these activities, and summarizes
information related to the population or stock, including regulatory
status under the MMPA and Endangered Species Act (ESA) and potential
biological removal (PBR), where known. PBR is defined by the MMPA as
the maximum number of animals, not including natural mortalities, that
may be removed from a marine mammal stock while allowing that stock to
reach or maintain its optimum sustainable population (as described in
NMFS' SARs). While no serious injury or mortality is anticipated or
authorized here, PBR and annual serious injury and mortality from
anthropogenic sources are included here as gross indicators of the
status of the species and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates represent the total estimate of
individuals within the geographic area, if known, that comprises that
stock. For some species, this geographic area may extend beyond U.S.
waters. All managed stocks in this region are assessed in NMFS' U.S.
Atlantic and Gulf of Mexico SARs (e.g., Hayes et al., 2022). All values
presented in Table 3 are the most recent available at the time of
publication (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 3--Marine Mammal Species \4\ Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\1\ abundance survey) \2\ SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Infraorder Cetacea--Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Atlantic white-sided dolphins... Lagenorhynchus acutus.. Western North Atlantic. -, -, N 93,233 (0.71, 54,443, 544 27
2016).
Common dolphins................. Delphinus delphis...... Western North Atlantic. -, -, N 172,974 (0.21, 1,452 390
145,216, 2016).
Family Phocoenidae (porpoises):
Harbor Porpoise................. Phocoena phocoena...... Gulf of Maine/Bay of -, -, N 95,543 (0.31, 74,034, 851 164
Fundy. 2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
Harbor Seal..................... Phoca vitulina......... Western North Atlantic. -, -, N 61,336 (0.08, 57,637, 1,729 339
2018).
Gray Seal....................... Halichoerus grypus..... Western North Atlantic. -, -, N 27,300 (0.22, 22,785, 1,389 4,453
2016).
Harp Seal....................... Pagophilus Western North Atlantic. -, -, N 7.6 M (UNK, 7.1, 2019) 426,000 178,573
groenlandicus.
[[Page 66139]]
Hooded Seal..................... Cystophora cristata.... Western North Atlantic. -, -, N 593,500 (UNK, UNK, UNK 1,680
2005).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
(<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/</a>; Committee on Taxonomy (2022)).
As indicated above, all seven species (with seven managed stocks)
in Table 3 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur. While several species
of whales have been documented seasonally in New England waters, the
spatial occurrence of these species is such that take is not expected
to occur, and they are not discussed further beyond the explanation
provided here. The humpback (Megaptera novaeangliae), fin (Balaenoptera
physalus), sei (Balaenoptera borealis), sperm (Physeter macrocephalus)
and North Atlantic right whales (Eubaleana glacialis) occur seasonally
in the Atlantic Ocean, offshore of Rhode Island. However, due to the
depths of Narragansett Bay and near shore location of the project area,
these marine mammals are unlikely to occur in the project area.
Therefore, OMAO did not request, and NMFS is not proposing to authorize
takes of these species.
Atlantic White-Sided Dolphin
Atlantic white-sided dolphins occur in the temperate waters of the
North Atlantic and specifically off the coast of North Carolina to
Maine in U.S. waters (Hayes et al., 2022). The Gulf of Maine population
of white-sided dolphin primarily occurs in continental shelf waters
from Hudson Canyon to Georges Bank, and in the Gulf of Maine and lower
Bay of Fundy. From January to May, this population occurs in low
numbers from Georges Bank to Jeffreys Ledge (off New Hampshire) with
even lower numbers south of Georges Bank. They are most common from
June through September from Georges Bank to lower Bay of Fundy, with
densities declining from October through December (Payne and Heinemann,
1990; Hayes et al., 2022).
Since stranding recordings for the Atlantic white-sided dolphin
began in Rhode Island in the late 1960s, this species has become the
third most frequently recorded small cetacean. There are occasional
unconfirmed opportunistic reports of white-sided dolphins in
Narragansett Bay, typically in fall and winter. Atlantic white-sided
dolphins in Rhode Island inhabit the continental shelf, with a slight
tendency to occur in shallower water in the spring when they are most
common (approximately 64 percent of records). Seasonal occurrence of
Atlantic white-sided dolphins decreases significantly following spring
with 21 percent of records in summer, 10 percent in winter, and 7.6
percent in fall (Kenny and Vigness-Raposa, 2010).
Mass strandings of up to 100 animals or more is common for this
species. In an analysis of stranded marine mammals in Cape Cod and
southeastern Massachusetts, Bogomolni et al. (2010) found that 69
percent of stranded white-sided dolphins were involved in mass
stranding events with no significant cause determined, and 21 percent
were classified as disease-related. Impacts from contaminants and
pesticides, as well as climate-related changes, pose the greatest
threats for Atlantic white-sided dolphins.
Common Dolphin
The common dolphin is one of the most widely distributed species of
cetaceans, found world-wide in temperate and subtropical seas. In the
North Atlantic, they are common along the shoreline of Massachusetts
and at sea sightings have been concentrated over the continental shelf
between the 100-meter (m) and 2000-m isobaths over prominent underwater
topography and east to the mid-Atlantic Ridge. The common dolphin
occurs from Cape Hatteras northeast to Georges Bank from mid-January to
May and in the Gulf of Maine from mid-summer to autumn (Hayes et al.,
2022).
Strandings occur year-round. In the stranding record for Rhode
Island, common dolphins are the second most frequently stranded
cetacean (exceeded only by harbor porpoises) and the most common
delphinid. There were 23 strandings in Rhode Island between 1972 and
2005 (Kenny and Vigness-Raposa, 2010). A short-beaked common dolphin
was most recently recorded in Narragansett Bay in October of 2016
(Hayes et al., 2022). There are no recent records of common dolphins
far up rivers, however such occurrences would only show up in the
stranding database if the stranding network responded, and there is no
centralized clearinghouse for opportunistic sightings of that type. In
Rhode Island, there are occasional opportunistic reports of common
dolphins in Narragansett Bay up as far as the Providence River, usually
in winter. The greatest threats for common dolphins include impacts
from contaminants, anthropogenic sound, and climate change (Hayes et
al., 2022).
Harbor Porpoise
Harbor porpoises occur in northern temperate and subarctic coastal
and offshore waters in both the Atlantic and Pacific Oceans. In the
western North Atlantic, harbor porpoises occur in the northern Gulf of
Maine and southern Bay of Fundy region in waters generally less than
150 m deep, primarily during the summer (July to September). During
fall (October to December) and spring (April to June), harbor porpoises
are widely dispersed between New Jersey and Maine. Lower densities of
harbor porpoise occur during the winter (January to March) in waters
off New York to New Brunswick, Canada (Hayes et al., 2022).
Harbor porpoises are the most stranded cetacean in Rhode Island.
Their occurrence is strongly seasonal and the highest occurrence is in
spring at approximately 70 percent of all
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records. Harbor porpoises may occur in Narragansett Bay during the
winter, but reports are second- and third-hand anecdotal reports
(Kenny, 2013). As harbor porpoises spend a significant amount of time
in nearshore areas, harbor porpoises are vulnerable to contaminants,
ship traffic, and physical habitat modifications in addition to fishery
bycatch and sources of anthropogenic underwater noise (Hall et al.,
2006; Todd et al., 2015; Oakley et al., 2017; Hayes et al., 2022).
Harbor Seal
Harbor seals occur in all nearshore waters of the North Atlantic
and North Pacific Oceans and adjoining seas above approximately
30[deg]N (Burns, 2009). They are year-round residents in the coastal
waters of eastern Canada and Maine (Katona et al., 1993), occurring
seasonally from southern New England to New Jersey from September
through late May (Schneider and Payne, 1983; Schroeder, 2000; Rees et
al., 2016, Toth et al., 2018). Harbor seals' northern movement occurs
prior to pupping season that takes place from May through June along
the Maine coast. In autumn to early winter, harbor seals move southward
from the Bay of Fundy to southern New England and mid-Atlantic waters
(Rosenfeld et al., 1988; Whitman and Payne, 1990; Jacobs and Terhune,
2000; Hayes et al., 2022). Overall, there are five recognized
subspecies of harbor seal, two of which occur in the Atlantic Ocean.
The western Atlantic harbor seal is the subspecies likely to occur in
the proposed project area. There is some uncertainly about the overall
population stock structure of harbor seals in the western North
Atlantic Ocean. However, it is theorized that harbor seals along the
eastern U.S. and Canada are all from a single population (Temte et al.,
1991; Anderson and Olsen, 2010).
Harbor seals are regularly observed around all coastal areas
throughout Rhode Island, and occasionally well inland up bays, rivers,
and streams. In general, rough estimates indicate that approximately
100,000 harbor seals occur in New England waters (DeAngelis, 2020).
Seals are very difficult to detect during surveys, since they tend to
be solitary and the usual sighting cue is only the seal's head above
the surface. Available data on harbor seals in New England are strongly
dominated by stranding records, which comprise 446 of 507 total records
for harbor seals (88 percent) (Kenny and Vigness-Raposa, 2010). Of the
available records, 52.5 percent are in spring, 31.2 percent in winter,
9.5 percent in summer, and 6.9 percent in fall. In Rhode Island, there
are no records offshore of the 90-meter isobath. Based upon seasonal
monitoring in Rhode Island, seals begin to arrive in Narragansett Bay
in September, with numbers slowly increasing in March before dropping
off sharply in April. By May, seals have left the Bay (DeAngelis,
2020).
Seasonal nearshore marine mammal surveys were conducted at NAVSTA
Newport between May 2016 and February 2017. The surveys were conducted
along the western shoreline of Coasters Harbor Island northward to
Coggeshall Point and eastward to include Gould Island. The only species
that was sighted during the survey was harbor seal. During the spring
survey of 2016, one live harbor seal was sighted on May 12 and one
harbor seal carcass was observed and reported to the Mystic Aquarium
Stranding Network (Moll, et al., 2016, 2017; Navy, 2017b). A group of
three harbor seals was sighted on February 1 2017, during the winter
survey.
In Rhode Island waters, harbor seals prefer to haul out on isolated
intertidal rock ledges and outcrops. Numerous Naval Station employees
have reported seals hauled out on an intertidal rock ledge named ``The
Sisters,'' which is north-northwest of Coddington Point and
approximately 3,500 ft (1,066.8 m) from the proposed project area (see
Figure 4-1 of the application) (NUWC Division, 2011). This haulout site
has been studied by the NUWC Division Newport since 2011 and has
demonstrated a steady increase in use during winter months when harbor
seals are present in the Bay. Harbor seals are rarely observed at ``The
Sisters'' haulout in the early fall (September-October) but sighted in
consistent numbers in mid-November (0-10 animals), and are regularly
observed with a gradual increase of more than 20 animals until numbers
peak in the upper 40s during March, typically at low tide. The number
of harbor seals begin to drop off in April and by mid-May, they are not
observed hauled out at all (DeAngelis, 2020). Haulout spaces at ``The
Sisters'' haulout site is primarily influenced by tide level, swell,
and wind direction (Moll et al., 2017; DeAngelis, 2020).
In addition to ``The Sisters'' haul out, there are 22 haulout sites
in Narragansett Bay (see Figure 4-1 in the application). During a 1 day
Narragansett Bay-wide count in 2018, there were at least 423 seals
observed and all 22 haulout sites were represented. Preliminary results
from the Bay-wide count for 2019 recorded 572 harbor seals, which also
included counts from Block Island (DeAngelis, 2020).
Gray Seal
Gray seals within U.S. waters are from the western North Atlantic
stock and are expected to be part of the eastern Canadian population.
The western North Atlantic stock is centered in Canadian waters,
including the Gulf of St. Lawrence and the Atlantic coasts of Nova
Scotia, Newfoundland, and Labrador, Canada, and the northeast U.S.
continental shelf (Hayes et al., 2022). In U.S. waters, year-round
breeding of approximately 400 animals has been documented on areas of
outer Cape Cod and Muskeget Island in Massachusetts.
Gray seal occurrences in Rhode Island are mostly represented by
stranding records--155 of 193 total records (80 percent). Gray seal
records in the region are primarily from the spring (approximately 87
percent), with much smaller numbers in all other seasons. Kenney and
Vigness-Raposa (2010) found strandings to be broadly distributed along
ocean-facing beaches in Long Island and Rhode Island, with a few spring
records in Connecticut. Habitat use by gray seals in Rhode Island is
poorly understood. They are seen mainly when stranded or hauled out,
and are infrequently observed at sea. There are very few observations
of gray seals in Rhode Island other than strandings. The annual numbers
of gray seal strandings in the Rhode Island study area since 1993 have
fluctuated markedly, from a low of 1 in 1999 to a high of 24 in 2011
(Kenney, 2020). The very strong seasonality of gray seal occurrence in
Rhode Island between March and June is linked to the timing of pupping
in January and February. Most stranded individuals encountered in Rhode
Island area appear to be post-weaning juveniles and starved or starving
juveniles (Nawojchik, 2002; Kenney, 2005). Annual informal surveys
conducted since 1994 observed a small number of gray seals in
Narragansett Bay in 2016, although the majority of seals observed were
harbor seals (ecoRI News, 2016).
Harp Seal
The harp seal is a highly migratory species, and its range can
extend from the Canadian Arctic to New Jersey (Sergeant, 1965; Stenson
and Sjare, 1997; Hayes et al., 2021). Harp seals are classified into
three stocks, which coincide with specific pupping sites on pack ice.
These pupping sites are as follows: (1) Eastern Canada, including the
areas off the coast of Newfoundland and Labrador and the area near the
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Magdalen Islands in the Gulf of St. Lawrence; (2) the West Ice off
eastern Greenland, and (3) the ice in the White Sea off the coast of
Russia ((Lavigne and Kovacs, 1988; Bonner, 1990; Hayes et al., 2021).
In U.S. waters, the species has an increasing presence in the coastal
waters between Maine and New Jersey with a general presence from
January through May (Hayes et al., 2021).
Harp seals in Rhode Island are known almost exclusively from
strandings (approximately 98 percent). Strandings are widespread on
ocean-facing beaches throughout Long Island and Rhode Island and the
records occur almost entirely during spring (approximately 68 percent)
and winter (approximately 30 percent). Harp seals are nearly absent in
summer and fall. Harp seals also make occasional appearances well
inland up rivers (Kenny and Vigness-Raposa, 2010). During late winter
of 2020, a healthy harp seal was observed hauled out and resting near
``The Sisters'' haulout site (DeAngelis, 2020).
Hooded Seal
The hooded seal is a highly migratory species, and its range can
extend from the Canadian Arctic to as far south as Puerto Rico
(Mignucci-Giannoni and Odell, 2001; Hayes et al., 2019). In U.S.
waters, the species has an increasing presence in the coastal waters
between Maine and Florida. Hooded seals in the U.S. are considered
members of the western North Atlantic stock and generally occur in New
England waters from January through May and further south off the
southeast U.S. coast and in the Caribbean in the summer and fall
seasons (McAlpine et al., 1999; Harris et al., 2001; and Mignucci-
Giannoni and Odell, 2001; Hayes et al., 2019).
Hooded seal occurrences in Rhode Island are predominately from
stranding records (approximately 99 percent). They are rare in summer
and fall but most common in the area during spring and winter (45
percent and 36 percent of all records, respectively) (Kenney, 2005;
Kenny and Vigness-Raposa, 2010). Hooded seal strandings are broadly
distributed across ocean-facing beaches in Rhode Island and they
occasionally occur well up rivers, but less often than harp seals.
Hooded seals have been recorded in Narragansett Bay but are considered
occasional visitors and are expected to be the least encountered seal
species in the Bay (RICRMC, 2010).
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007, 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). Note that no direct measurements of
hearing ability have been successfully completed for mysticetes (i.e.,
low-frequency cetaceans). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (dB) threshold from the normalized composite audiograms, with
the exception for lower limits for 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 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Generalized hearing
Hearing group range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen whales).... 7 Hz to 35 kHz.
Mid-frequency (MF) cetaceans (dolphins, toothed 150 Hz to 160 kHz.
whales, beaked whales, bottlenose whales).
High-frequency (HF) cetaceans (true porpoises, 275 Hz to 160 kHz.
Kogia, river dolphins, Cephalorhynchid,
Lagenorhynchus cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) (true seals). 50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions 60 Hz to 39 kHz.
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.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section provides a 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 whether those impacts are reasonably
expected to, or reasonably likely to, adversely affect the species or
stock through effect on annual rates of recruitment or survival.
Acoustic effects on marine mammals during the specified activities
can occur from vibratory and impact pile driving as well as rotary
drilling and DTH mono-hammer events. The effects of underwater noise
from OMAO's proposed activities have the potential to result in Level A
and Level B harassment of marine mammals in the proposed 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
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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
decibels (dB) from day to day (Richardson et al., 1995). The result is
that, depending on the source type and its intensity, sound from the
specified activities may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
In-water construction activities associated with the project would
include impact and vibratory pile driving, vibratory removal, and
rotary drilling and DTH mono-hammer excavation events. The sounds
produced by these activities fall into one of two general sound types:
impulsive and non-impulsive. Impulsive sounds (e.g., explosions, 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., machinery operations such as drilling or
dredging, vibratory pile driving, underwater chainsaws, and active
sonar systems) can be broadband, narrowband or tonal, brief or
prolonged (continuous or intermittent), and typically do not have the
high peak sound pressure with raid rise/decay time that impulsive
sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). DTH mono-hammer
excavation includes the use of rotary drilling (non-impulsive sound
source) and percussive hammering (impulsive sound source). The
distinction between impulsive and non-impulsive sound sources 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 mono-hammer. 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 considered
impulsive. Vibratory hammers install piles by vibrating them and
allowing the weight of the hammer to push them into the sediment.
Vibratory hammers produce non-impulsive, continuous sounds. Vibratory
hammering generally produces sounds pressure levels (SPLs) 10 to 20 dB
lower than impact pile driving of the same-sized pile (Oestman et al.,
2009). Rise time is slower, reducing the probability and severity of
injury, and sound energy is distributed over a greater amount of time
(Nedwell and Edwards, 2002; Carlson et al., 2005).
DTH systems, involving both mono-hammers and cluster-hammers, and
rotary drills will also be used during the proposed construction. In
rotary drilling, the drill bit rotates on the rock while the drill rig
applies pressure. The bit rotates and grinds continuously to fracture
the rock and create a hole. Rotary drilling is considered an
intermittent, non-impulsive noise source. 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). Rock socketing involves
using DTH equipment to create a hole in the bedrock inside which the
pile is placed to give it lateral and longitudinal strength. The sounds
produced by the DTH methods 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 OMAO's proposed activities on
marine mammals could be generated from both non-acoustic and acoustic
stressors. Potential non-acoustic stressors include the physical
presence of the equipment, vessels, and personnel; however, we expect
that any animals that approach the project site(s) close enough to be
harassed due to the presence of equipment or personnel would be within
the Level A or Level B harassment zones from pile driving/removal and
would already be subject to harassment from the in-water activities.
Therefore, any impacts to marine mammals are expected to primarily be
acoustic in nature. Acoustic stressors include heavy equipment
operation during pile installation and removal (i.e., impact and
vibratory pile driving and removal, rotary drilling, and DTH mono-
hammer excavation).
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic
environment from pile driving and removal equipment is the primary
means by which marine mammals may be harassed from OMAO's specified
activities. 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). Generally,
exposure to pile driving and removal and other construction 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 as 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 demolition 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. mother 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.,
2003; 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
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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; Henderson et al., 2008).
PTS levels for marine mammals are estimates, because there are limited
empirical data measuring PTS in marine mammals (e.g., Kastak et al.,
2008), largely due to the fact that, for various ethical reasons,
experiments involving anthropogenic noise exposure at levels inducing
PTS are not typically pursued or authorized (NMFS, 2018).
Temporary Threshold Shift (TTS)--TTS is a temporary, reversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range above a previously established
reference level (NMFS, 2018). Based on data from cetacean TTS
measurements (see Southall et al., 2007), a TTS of 6 dB is considered
the minimum threshold shift clearly larger than any day-to-day or
session-to-session variation in a subject's normal hearing ability
(Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in
Finneran (2016), marine mammal studies have shown the amount of TTS
increases with cumulative sound exposure level (SEL<INF>cum</INF>) in
an accelerating fashion: At low exposures with lower SEL<INF>cum,</INF>
the amount of TTS is typically small and the growth curves have shallow
slopes. At exposures with higher SEL<INF>cum</INF>, 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.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
For cetaceans, published data on the onset of TTS are limited to the
captive bottlenose dolphin (Tursiops truncatus), beluga whale
(Delphinapterus leucas), harbor porpoise, and Yangtze finless porpoise
(Neophocoena asiaeorientalis), and for pinnipeds in water, measurements
of TTS are limited to harbor seals, elephant seals (Mirounga
angustirostris), and California sea lions (Zalophus californianus).
These studies examine hearing thresholds measured in marine mammals
before and after exposure to intense sounds. The difference between the
pre-exposure and post-exposure thresholds can be used to determine the
amount of threshold shift at various post-exposure times. The amount
and onset of TTS depends on the exposure frequency. Sounds at low
frequencies, well below the region of best sensitivity, are less
hazardous than those at higher frequencies, near the region of best
sensitivity (Finneran and Schlundt, 2013). At low frequencies, onset-
TTS exposure levels are higher compared to those in the region of best
sensitivity (i.e., a low frequency noise would need to be louder to
cause TTS onset when TTS exposure level is higher), as shown for harbor
porpoises and harbor seals (Kastelein et al., 2019a, 2019b, 2020a,
2020b). In addition, TTS can accumulate across multiple exposures, but
the resulting TTS will be less than the TTS from a single, continuous
exposure with the same SEL (Finneran et al., 2010; Kastelein et al.,
2014; Kastelein et al., 2015a; Mooney et al., 2009). This means that
TTS predictions based on the total, cumulative SEL will overestimate
the amount of TTS from intermittent exposures such as sonars and
impulsive sources. Nachtigall et al. (2018) and Finneran (2018)
describe the measurements of hearing sensitivity of multiple odontocete
species (bottlenose dolphin, harbor porpoise, beluga, and false killer
whale (Pseudorca crassidens)) when a relatively loud sound was preceded
by a warning sound. These captive animals were shown to reduce hearing
sensitivity when warned of an impending intense sound. Based on these
experimental observations of captive animals, the authors suggest that
wild animals may dampen their hearing during prolonged exposures or if
conditioned to anticipate intense sounds. Another study showed that
echolocating animals (including odontocetes) might have anatomical
specializations that might allow for conditioned hearing reduction and
filtering of low-frequency ambient noise, including increased stiffness
and control of middle ear structures and placement of inner ear
structures (Ketten et al., 2021). Data available on noise-induced
hearing loss for mysticetes are currently lacking (NMFS, 2018).
Activities for this project include impact and vibratory pile
driving, vibratory pile removal, rotary drilling, and DTH mono-hammer
excavation. There would likely be pauses in activities producing the
sound during each day. Given these pauses and the fact that many marine
mammals are likely moving through the project areas and not remaining
for extended periods of time, the potential for threshold shift
declines.
Behavioral harassment--Exposure to noise from pile driving and
removal also has the potential to behaviorally disturb marine mammals.
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;
Southall et al., 2021). 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
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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).
The following subsections provide examples of behavioral responses
that provide an idea of the variability in behavioral responses that
would be expected given the differential sensitivities of marine mammal
species to sound and the wide range of potential acoustic sources to
which a marine mammal may be exposed. Behavioral responses that could
occur for a given sound exposure should be determined from the
literature that is available for each species, or extrapolated from
closely related species when no information exists, along with
contextual factors. 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. There are broad categories of potential
response, which we describe in greater detail here, that include
alteration of dive behavior, alteration of foraging behavior, effects
to respiration, interference with or alteration of vocalization,
avoidance, and flight.
Pinnipeds may increase their haul out time, possibly to avoid in-
water disturbance (Thorson and Reyff, 2006). 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.
Alteration of Dive Behavior--Changes in dive behavior can vary
widely, and may consist of increased or decreased dive times and
surface intervals as well as changes in the rates of ascent and descent
during a dive (e.g., Frankel and Clark, 2000; Costa et al., 2003; Ng
and Leung, 2003; Nowacek et al., 2004; Goldbogen et al., 2013). Seals
exposed to non-impulsive sources with a received sound pressure level
within the range of calculated exposures (142-193 dB re 1 [mu]Pa), have
been shown to change their behavior by modifying diving activity and
avoidance of the sound source (G[ouml]tz et al., 2010; Kvadsheim et
al., 2010). Variations in dive behavior may reflect interruptions in
biologically significant activities (e.g., foraging) or they may be of
little biological significance. The impact of an alteration to dive
behavior resulting from an acoustic exposure depends on what the animal
is doing at the time of the exposure and the type and magnitude of the
response.
Alteration of Feeding Behavior--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; Melc[oacute]n et al., 2012). In
addition, behavioral state of the animal plays a role in the type and
severity of a behavioral response, such as disruption to foraging
(e.g., Silve et al., 2016; Wensveen et al., 2017). 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.
Goldbogen et al. (2013) indicate that disruption of feeding and
displacement could impact individual fitness and health. However, for
this to be true, we would have to assume that an individual could not
compensate for this lost feeding opportunity by either immediately
feeding at another location, by feeding shortly after cessation of
acoustic exposure, or by feeding at a later time. There is no
indication this is the case, particularly since unconsumed prey would
likely still be available in the environment in most cases following
the cessation of acoustic exposure. Information on or estimates of the
energetic requirements of the individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal will help better inform a determination of whether
foraging disruptions incur fitness consequences.
Respiration--Respiration naturally varies with different behaviors,
and variations in respiration rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Studies with captive harbor porpoises showed increased
respiration rates upon introduction of acoustic alarms (Kastelein et
al., 2001; Kastelein et al., 2006a) and emissions for underwater data
transmission (Kastelein et al., 2005). Various studies also have shown
that species and signal characteristics are important factors in
whether respiration rates are unaffected or change, again highlighting
the importance in understanding species differences in the tolerance of
underwater noise when determining the potential for impacts resulting
from anthropogenic sound exposure (e.g., Kastelein et al., 2005, 2006,
2018; Gailey et al., 2007; Isojunno et al., 2018).
Vocalization--Marine mammals vocalize for different purposes and
across multiple modes, such as whistling, echolocation click
production, calling, and singing. Changes in vocalization behavior in
response to anthropogenic noise can occur for any of these modes and
may result from a need to compete with an increase in background noise
or may reflect increased vigilance or a startle response. For example,
in the presence of potentially masking signals, humpback whales and
killer whales (Orcinus orca) have been observed to increase the length
of their songs (Miller et al., 2000; Fristrup et al., 2003; Foote et
al., 2004), while right whales have been observed to shift the
frequency content of their calls upward while reducing the rate of
calling in areas of increased anthropogenic noise (Parks et al., 2007;
Rolland et al., 2012). Killer whales off the northwestern coast of the
United States have been observed to increase the duration of primary
calls once a threshold in observing vessel density (e.g., whale
watching) was reached, which has been suggested as a response to
increased masking noise produced by the vessels (Foote et al., 2004;
NOAA, 2014). In some cases, however, animals may cease or alter sound
production in response to underwater sound (e.g., Bowles et al., 1994;
Castellote et al., 2012; Cerchio et al., 2014). Studies also
demonstrate that even low levels of noise received far from the noise
source can induce changes in vocalization and/or
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behavioral responses (Blackwell et al., 2013, 2015).
Avoidance--Avoidance is the displacement of an individual from an
area or migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). Avoidance is qualitatively
different from the flight response, but also differs in the magnitude
of the response (i.e., directed movement, rate of travel, etc.). Often
avoidance is temporary, and animals return to the area once the noise
has ceased. Acute avoidance responses have been observed in captive
porpoises and pinnipeds exposed to a number of different sound sources
(Kastelein et al., 2001; Finneran et al., 2003; Kastelein et al.,
2006a; Kastelein et al., 2006b; Kastelein et al., 2015b; Kastelein et
al., 2015c; Kastelein et al., 2018). Short-term avoidance of seismic
surveys, low frequency emissions, and acoustic deterrents have also
been noted in wild populations of odontocetes (Bowles et al., 1994;
Goold, 1996; Goold and Fish, 1998; Morton and Symonds, 2002; Hiley et
al., 2021) and to some extent in mysticetes (Malme et al., 1984;
McCauley et al., 2000; Gailey et al., 2007). Longer-term displacement
is possible, however, which may lead to changes in abundance or
distribution patterns of the affected species in the affected region if
habituation to the presence of the sound does not occur (e.g.,
Blackwell et al., 2004; Bejder et al., 2006; Teilmann et al., 2006).
Forney et al. (2017) described the potential effects of noise on
marine mammal populations with high site fidelity, including
displacement and auditory masking. In cases of Western gray whales
(Eschrichtius robustus) (Weller et al., 2006) and beaked whales
(Ziphius cavirostris), anthropogenic effects in areas where they are
resident or exhibit site fidelity could cause severe biological
consequences, in part because displacement may adversely affect
foraging rates, reproduction, or health, while an overriding instinct
to remain in the area could lead to more severe acute effects.
Avoidance of overlap between disturbing noise and areas and/or times of
particular importance for sensitive species may be critical to avoiding
population-level impacts because (particularly for animals with high
site fidelity) there may be a strong motivation to remain in the area
despite negative impacts.
Flight Response--A flight response is a dramatic change in normal
movement to a directed and rapid movement away from the perceived
location of a sound source. The flight response differs from other
avoidance responses in the intensity of the response (e.g., directed
movement, rate of travel). Relatively little information on flight
responses of marine mammals to anthropogenic signals exist, although
observations of flight responses to the presence of predators have
occurred (Connor and Heithaus, 1996). The result of a flight response
could range from brief, temporary exertion and displacement from the
area where the signal provokes flight to, in extreme cases, marine
mammal strandings (Evans and England, 2001). There are limited data on
flight response for marine mammals in water; however, there are
examples of this response in species on land. For instance, the
probability of flight responses in Dall's sheep Ovis dalli dalli (Frid,
2003), hauled out ringed seals (Phoca hispida) (Born et al., 1999),
Pacific brant (Branta bernicla nigricans), and Canada geese (B.
canadensis) increased as a helicopter or fixed-wing aircraft more
directly approached groups of these animals (Ward et al., 1999).
However, it should be noted that response to a perceived predator does
not necessarily invoke flight (Ford and Reeves, 2008), and whether
individuals are solitary or in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been observed in marine mammals, but studies
involving fish and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates and efficiency (e.g.,
Beauchamp and Livoreil, 1997; Fritz et al., 2002; Purser and Radford,
2011). In addition, chronic disturbance can cause population declines
through reduction of fitness (e.g., decline in body condition) and
subsequent reduction in reproductive success, survival, or both (e.g.,
Harrington and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998).
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than one day and not
recurring on subsequent days is not considered particularly severe
unless it could directly affect reproduction or survival (Southall et
al., 2007). Note that there is a difference between multi-day
substantive behavioral reactions and multi-day anthropogenic
activities. For example, just because an activity lasts for multiple
days does not necessarily mean that individual animals are either
exposed to activity-related stressors for multiple days or, further,
exposed in a manner resulting in sustained multi-day substantive
behavioral responses.
Many of the contextual factors resulting from the behavioral
response studies (e.g., close approaches by multiple vessels or
tagging) would not occur during the proposed action. In 2016, the
Alaska Department of Transportation and Public Facilities (ADOT&PF)
documented observations of marine mammals during construction
activities (i.e., pile driving) at the Kodiak Ferry Dock (see 80 FR
60636, October 7, 2015). In the marine mammal monitoring report for
that project (ABR, 2016), 1,281 Steller sea lions were observed within
the Level B disturbance zone during pile driving or drilling (i.e.,
documented as Level B harassment take). 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. 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. The proposed action involves impact and vibratory pile
driving, vibratory pile removal, rotary drilling, and DTH mono-hammer
excavation. Given the similarities in activities and habitat (e.g.,
cool-temperate waters, industrialized area), we expect similar
behavioral responses from the same and similar species affected by
OMAO's proposed action. That is, disturbance, if any, is likely to be
temporary and localized (e.g., small area movements).
To assess the strength of behavioral changes and responses to
external sounds and SPLs associated with changes in behavior, Southall
et al., (2007) developed and utilized a severity scale, which is a 10
point scale ranging from no effect (labeled 0), effects not likely to
influence vital rates (low; labeled from 1 to 3), effects that could
affect vital rates (moderate; labeled 4 to
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6), to effects that were thought likely to influence vital rates (high;
labeled 7 to 9). Southall et al., (2021) updated the severity scale by
integrating behavioral context (i.e., survival, reproduction, and
foraging) into severity assessment. For non-impulsive sounds (i.e.,
similar to the sources used during the proposed action), data suggest
that exposures of pinnipeds to sources between 90 and 140 dB re 1
[mu]Pa do not elicit strong behavioral responses; no data were
available for exposures at higher received levels for Southall et al.,
(2007) to include in the severity scale analysis. Reactions of harbor
seals were the only available data for which the responses could be
ranked on the severity scale. For reactions that were recorded, the
majority (17 of 18 individuals/groups) were ranked on the severity
scale as a 4 (defined as moderate change in movement, brief shift in
group distribution, or moderate change in vocal behavior) or lower; the
remaining response was ranked as a 6 (defined as minor or moderate
avoidance of the sound source).
Habituation--Habituation can occur when an animal's response to a
stimulus wanes with repeated exposure, usually in the absence of
unpleasant associated events (Wartzok et al., 2003). Animals are most
likely to habituate to sounds that are predictable and unvarying. It is
important to note that habituation is appropriately considered as a
``progressive reduction in response to stimuli that are perceived as
neither aversive nor beneficial,'' rather than as, more generally,
moderation in response to human disturbance (Bejder et al., 2009). The
opposite process is sensitization, when an unpleasant experience leads
to subsequent responses, often in the form of avoidance, at a lower
level of exposure. As noted, behavioral state may affect the type of
response. For example, animals that are resting may show greater
behavioral change in response to disturbing sound levels than animals
that are highly motivated to remain in an area for feeding (Richardson
et al., 1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments
with captive marine mammals have showed pronounced behavioral
reactions, including avoidance of loud sound sources (Ridgway et al.,
1997; Finneran et al., 2003). Observed responses of wild marine mammals
to loud impulsive sound sources (typically seismic airguns or acoustic
harassment devices) have been varied but often consist of avoidance
behavior or other behavioral changes suggesting discomfort (Morton and
Symonds, 2002; see also Richardson et al., 1995; Nowacek et al., 2007).
Stress responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker 2000; Romano
et al., 2002b) and, more rarely, studied in wild populations (e.g.,
Romano et al., 2002a). For example, Rolland et al. (2012) found that
noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to
acoustic stressors and that it is possible that some of these would be
classified as ``distress.'' In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003), however
distress is an unlikely result of these projects based on observations
of marine mammals during previous, similar projects.
Auditory Masking--Sound can disrupt behavior through masking, or
interfering with, an animal's ability to detect, recognize, or
discriminate between acoustic signals of interest (e.g., those used for
intraspecific communication and social interactions, prey detection,
predator avoidance, navigation) (Richardson et al., 1995). 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. Narragansett Bay
supports cargo vessel traffic as well as numerous recreational and
fishing vessels, and background sound levels in the proposed project
area are already elevated.
Airborne Acoustic Effects--Pinnipeds that occur near the project
site could be
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exposed to airborne sounds associated with pile driving and removal
that have the potential to cause behavioral harassment, depending on
their distance from pile driving 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 likely previously
have been `taken' because of exposure to underwater sound above the
behavioral harassment thresholds, which are generally 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.
Marine Mammal Habitat Effects
OMAO's proposed construction activities could have localized,
temporary impacts on marine mammal habitat, including 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 areas (see discussion below). Elevated
levels of underwater noise would ensonify the project areas 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.
A temporary and localized increase in turbidity near the seafloor
would occur in the immediate area surrounding the area where piles are
installed or removed. In general, turbidity associated with pile
installation is localized to about a 25-ft (7.6 m) radius around the
pile (Everitt et al., 1980). Turbidity and sedimentation effects are
expected to be short-term, minor, and localized. Re-suspended sediments
in Coddington Cove are expected to remain in Coddington Cove due to the
circular nature of the currents with ambient conditions returning a few
hours after completion of construction. Cetaceans are not expected to
be close enough to the pile driving areas to experience effects of
turbidity, and any pinnipeds could avoid localized areas of turbidity.
Therefore, we expect the impact from increased turbidity levels to be
discountable to marine mammals and do not discuss it further.
In-Water Construction Effects on Potential Foraging Habitat
The area likely impacted by the project is relatively small
compared to the available habitat in Narragansett Bay. In addition, the
area is highly influenced by anthropogenic activities and habitat in
this area has been previously disturbed by as a part of offshore
remediation activities. The total seafloor area affected by pile
installation and removal is a small area compared to the vast amount of
habitat available to marine mammals in the area. All marine mammal
species using habitat near the proposed project area are primarily
transiting the area. There are no known foraging or haulout areas
within one half mile of the proposed project area. Furthermore, pile
driving and removal at the project site would not obstruct long-term
movements or migration of marine mammals.
Avoidance by potential prey (i.e., fish) of the immediate area due
to the temporary loss of this foraging habitat is also possible. The
duration of fish and marine mammal 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 or marine mammals of the disturbed area would still leave
significantly large areas of fish and marine mammal foraging habitat in
the nearby vicinity.
Effects on Potential Prey
Sound may affect marine mammals through impacts on the abundance,
behavior, or distribution of prey species (e.g., fish). Marine mammal
prey varies by species, season, and location. Here, we describe studies
regarding the effects of noise on known marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick and Mann, 1999; Fay,
2009). Depending on their hearing anatomy and peripheral sensory
structures, which vary among species, fishes hear sounds using pressure
and particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to noise depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Additional studies
have documented effects of pile driving on fish; 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).
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
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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 fishes from pile driving and removal and
construction 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.
Construction activities have the potential to have adverse impacts
on forage fish in the project area in the form of increased turbidity.
Forage fish form a significant prey base for many marine mammal species
that occur in the project area. Increased turbidity is expected to
occur in the immediate vicinity (on the order of 10 ft (3 m) or less)
of construction activities. Turbidity within the water column has the
potential to reduce the level of oxygen in the water and irritate the
gills of prey fish in the proposed project area. However, fish in the
proposed project area would be able to move away from and avoid the
areas where increase turbidity may occur. Given the limited area
affected and ability of fish to move to other areas, any effects on
forage fish are expected to be minor or negligible.
In summary, given the short daily duration of sound associated with
individual pile driving and removal events and the relatively small
areas being affected, pile driving and removal activities associated
with the proposed actions are not likely to have a permanent, adverse
effect on any fish habitat, or populations of fish species. Any
behavioral avoidance by fish of the disturbed area would still leave
significantly large areas of fish and marine mammal foraging habitat in
the nearby vicinity. Thus, we conclude that impacts of the specified
activities 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
determinations.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of the acoustic sources (i.e., pile driving and removal, DTH, and
rotary drilling) has the potential to result in disruption of
behavioral patterns for individual marine mammals. There is also some
potential for auditory injury (Level A harassment) to result, primarily
for high frequency species and phocids because predicted auditory
injury zones are larger than for mid-frequency species. Auditory injury
is unlikely to occur for mid-frequency species. The proposed mitigation
and monitoring measures are expected to minimize the severity of the
taking to the extent practicable.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic thresholds above which NMFS believes the best
available science indicates marine mammals will be behaviorally
harassed or incur some degree of permanent hearing impairment; (2) the
area or volume of water that will be ensonified above these levels in a
day; (3) the density or occurrence of marine mammals within these
ensonified areas; and, (4) the number of days of activities. We note
that while these factors can contribute to a basic calculation to
provide an initial prediction of potential takes, additional
information that can qualitatively inform take estimates is also
sometimes available (e.g., previous monitoring results or average group
size). Below, we describe the factors considered here in more detail
and present the proposed take estimates.
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur PTS of some degree (equated to Level A
harassment). Thresholds have also been developed identifying the
received level of in-air sound above which exposed pinnipeds would
likely be behaviorally harassed.
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g.,
scientific sonar) sources. Generally speaking, Level B harassment take
estimates based on these behavioral harassment thresholds are expected
to include any likely takes by TTS as, in most cases, the likelihood of
TTS occurs at distances from the source less than those at which
behavioral harassment is likely. TTS of a sufficient degree can
manifest as behavioral harassment, as reduced hearing sensitivity and
the potential reduced opportunities to detect important signals
(conspecific communication, predators, prey) may result in changes in
behavior patterns that would not otherwise occur.
OMAO's proposed activities includes the use of continuous
(vibratory hammer/rotary drill/DTH mono-hammer) and impulsive (impact
hammer/DTH mono-hammer) sources, and therefore the RMS SPL thresholds
of 120 and 160 dB re 1 [mu]Pa are applicable.
[[Page 66149]]
Level A Harassment--NMFS' Technical Guidance for Assessing the
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0)
(Technical Guidance, 2018) identifies dual criteria to assess auditory
injury (Level A harassment) to five different marine mammal groups
(based on hearing sensitivity) as a result of exposure to noise from
two different types of sources (impulsive or non-impulsive). OMAO's
proposed activity includes the use of impulsive (impact hammer/DTH
mono-hammer) and non-impulsive (vibratory hammer/rotary drill/DTH mono-
hammer) sources.
These thresholds are provided in the table below. The references,
analysis, and methodology used in the development of the thresholds are
described in NMFS' 2018 Technical Guidance, which may be accessed at:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lp,0-pk,flat: 219 Cell 2: LE,p,LF,24h: 199 dB.
dB; LE,p,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lp,0-pk,flat: 230 Cell 4: LE,p,MF,24h: 198 dB.
dB; LE,p,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lp,0-pk,flat: 202 Cell 6: LE,p,HF,24h: 173 dB.
dB; LE,p,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lp,0-pk.flat: 218 Cell 8: LE,p,PW,24h: 201 dB.
dB; LE,p,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lp,0-pk,flat: 232 Cell 10: LE,p,OW,24h: 219 dB.
dB; LE,p,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric 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 are recommended for consideration.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [mu]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to be
more reflective of International Organization for Standardization standards (ISO 2017). The subscript ``flat''
is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized
hearing range of marine mammals (i.e., 7 Hz to 160 kHz). 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 weighted
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 thresholds will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
The sound field in the project area is the existing background
noise plus additional construction noise from the proposed project.
Marine mammals are expected to be affected via sound generated by the
primary components of the project (i.e., impact pile driving, vibratory
pile driving, vibratory pile removal, rotary drilling, and DTH).
The intensity of underwater sound is greatly influenced by factors
such as the size and type of piles, type of driver or drill, and the
physical environment in which the activity takes place. In order to
calculate distances to the Level A harassment and Level B harassment
thresholds for the methods and piles being used in this project, NMFS
used representative source levels (Table 6) from acoustic monitoring at
other locations.
Table 6--Source Levels for Proposed Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
SEL (dB re 1
Method Pile type Pile diameter Peak (dB re 1 RMS (dB re 1 [mu]Pa 2-sec Reference
[mu]Pa) [mu]Pa) sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Extraction............ Steel pipe \1\............... 12'' 171 155 155 Caltrans 2020, Table
1.2-1d.
Timber....................... 12'' NA 152 NA NMFS 2021a, Table 4.
Vibratory Installation.......... Steel pipe................... 18'' NA 162 \2\ 162 NAVFAC Mid-Atlantic
2019, Table 6-4.
Sheet pile................... Z26-700 \3\ NA 156 NA NMFS 2019, p.37846.
Steel pipe................... 30'' NA 167 167 Navy 2015, p.14.
Casing/shaft for steel pipe.. 36'' NA 175 175 NAVFAC Mid-Atlantic
2019, Table 6-4.
DTH Mono-hammer................. Steel pipe................... 18'' 172 167 146 Egger, 2021; Guan and
Miner 2020; Heyvaert
and Reyff, 2021.
Casing/shaft for steel pipe.. 36'' \4\ 194 167 164 Reyff and Heyvaert
2019; Reyff 2020; and
Denes et al. 2019.
Rotary Drilling................. Steel pipe................... 18'' and 30'' NA 154 NA Dazey et al. 2012.
Impact Install.................. Steel pipe \5\............... 18'' 208 187 176 Caltrans 2020, Table
1.2-1a.
Steel pipe................... 30'' 211 196 181 NAVFAC Southwest 2020,
p.A-4.
Vibratory Installation/ Steel pipe................... 16'' NA 162 162 NAVFAC Mid-Atlantic
Extraction. 2019, Table 6-4.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 13-inch steel pipe used as proxy because data were not available for vibratory install/extract of 12-inch steel pipe.
\2\ Although conservative, this 162 dB RMS is consistent with source level value used for 18-inch steel pipe in for Dry Dock 1 at Portsmouth Naval
Shipyard (84 FR 13252, April 4, 2019).
\3\ 30-inch steel pipe pile used as the proxy source for vibratory driving of steel sheet piles because data were not available for Z26-700 (Navy 2015
[p. 14]).
\4\ Guidance from NMFS states: For each metric, select the highest SL provided among these listed references (Reyff and Heyvaert, 2019); (Reyff J.,
2020); (Denes et al., 2019).
\5\ Impact install of 20-inch steel pipe used as proxy because data were not available for 18-inch.
[[Page 66150]]
Notes: All SPLs are unattenuated; dB = decibels; NA = Not applicable/Not available; RMS = root mean square; SEL = sound exposure level; Caltrans =
California Department of Transportation; NAVFAC = Naval Facilities Engineering Systems Command; dB re 1 [mu]Pa = dB referenced to a pressure of 1
microPascal, measures underwater SPL. dB re 1 [mu]Pa2-sec = dB referenced to a pressure of 1 microPascal squared per second, measures underwater SEL.
Single strike SEL are the proxy source levels presented for impact pile driving and were used to calculate distances to PTS. All data referenced at 10
meters.
NMFS recommends treating DTH systems as both impulsive and
continuous, non-impulsive sound source types simultaneously. Thus,
impulsive thresholds are used to evaluate Level A harassment, and
continuous thresholds are used to evaluate Level B harassment. With
regards to DTH mono-hammers, NMFS recommends proxy levels for Level A
harassment based on available data regarding DTH systems of similar
sized piles and holes (Denes et al., 2019; Guan and Miner, 2020; Reyff
and Heyvaert, 2019; Reyff, 2020; Heyvaert and Reyff, 2021) (Table 1
includes number of piles and duration; Table 6 includes sound pressure
levels for each pile type). At the time of the Navy's application
submission, NMFS recommended that the RMS sound pressure level at 10 m
should be 167 dB when evaluating Level B harassment (Heyvaert and
Reyff, 2021 as cited in NMFS 2021b) for all DTH pile/hole sizes.
However, since that time, NMFS has received additional clarifying
information regarding DTH data presented in Reyff and Heyvaert (2019)
and Reyff (2020) that allows for different RMS sound pressure levels at
10 m to be recommended for piles/holes of varying diameters. Therefore,
NMFS proposes to use the following proxy RMS sound pressure levels at
10 m to evaluate Level B harassment from this sound source in this
analysis (Table 6): 167 dB RMS for the 18-inch steel pipe piles
(Heyvaert and Reyff, 2021) and 174 dB RMS for the 36 inch steel shafts
(Reyff and Heyvaert, 2019; Reyff, 2020).
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 * log<INF>10</INF> (R<INF>1</INF>/R<INF>2</INF>),
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R<INF>1</INF> = the distance of the modeled SPL from the driven
pile, and
R<INF>2</INF> = the distance from the driven pile of the initial
measurement.
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, known as practical spreading. As
is common practice in coastal waters, here we assume practical
spreading (4.5 dB reduction in sound level for each doubling of
distance). Practical spreading was used to determine sound propagation
for this project.
The TL model described above was used to calculate the expected
noise propagation from vibratory pile driving/extracting, impact pile
driving, rotary drilling, and DTH mono-hammer excavation using
representative source levels to estimate the harassment zones or area
exceeding the noise criteria. Utilizing the described practical
spreading model, NMFS calculated the Level B isopleths shown in Tables
7 and 8. The largest calculated Level B isopleth, with the exception of
concurrent activities, discussed below, is 46,416 m for the vibratory
installation of the 36'' steel casing/shaft guide piles with rock
socket to build the small boat floating dock; however, this distance is
truncated by shoreline in all directions, so sound would not reach the
full distance of the calculated Level B harassment isopleth. This
activity would generate a maximum ensonified area of 3.31 km\2\ (Table
8).
Level A Harassment Zones
The ensonified area associated with Level A harassment is
technically more challenging to predict due to the need to account for
a duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the Technical Guidance that can be used
to relatively simply predict an isopleth distance for use in
conjunction with marine mammal density or occurrence to help predict
potential takes. We note that because of some of the assumptions
included in the methods underlying this optional tool, we anticipate
that the resulting isopleth estimates are typically going to be
overestimates of some degree, which may result in an overestimate of
potential take by Level A harassment. However, this optional tool
offers the best way to estimate isopleth distances when more
sophisticated modeling methods are not available or practical. For
stationary sources such as pile driving, the optional User Spreadsheet
tool predicts the distance at which, if a marine mammal remained at
that distance for the duration of the activity, it would be expected to
incur PTS. Inputs used in the optional User Spreadsheet tool are
reported in Tables 1 (number piles/day and duration to drive a single
pile) and 6 (source levels/distance to source levels). The resulting
estimated isopleths are reported below in Tables 7 and 8. The largest
Level A isopleth would be generated by the impact driving of the 30''
steel pipe pile at the proposed pier for high-frequency cetaceans
(3,500.3 m; Table 7). This activity would have a maximum ensonified
area of 6.49 km\2\ (Table 7). Excluding concurrent activities,
described below, the largest calculated Level B isopleth would be
generated by the vibratory installation of the 36'' steel casing/shaft
guide piles at the proposed small boat floating dock (46,416 m; Table
8), though as noted above, this distance would be truncated by
shoreline in all directions, so sound would not reach the full distance
of the calculated Level B harassment isopleth. This activity would have
a maximum ensonified area of 3.31 km\2\ (Table 8).
[[Page 66151]]
Table 7--Maximum Distances to Level A Harassment and Level B Harassment Thresholds for Impulsive Sound
[Impact Hammer and DTH Mono-Hammer]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A (PTS onset) harassment Level B
------------------------------------------------ (behavioral)
harassment
Maximum Maximum Maximum ---------------
distance to distance to distance to Maximum
185 dB SELcum 155 dB SELcum 185 dB SELcum distance 160
Structure Pile size and type Activity threshold(m)/ threshold(m)/ threshold(m)/ dB RMS SPL
area of area of area of (120 dB DTH)
harassment harassment harassment threshold (m)/
zone (km\2\) zone (km\2\) zone (km\2\) area of
harassment
zone (km\2\)
MF cetacean HF cetacean Phocid All Marine
Mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bulkhead construction (Combination 18'' steel pipe......... Impact Install......... 48.5/0.0037 1,624.7/0.66 729.9/0.21 631/0.16
Pipe/Z-pile).
DTH Mono-Hammer........ 4.6/0.000033 154.2/0.028 69.3/0.0075 13,594/3.31
Trestle (Bents 1-18)................. 18'' steel pipe......... Impact Install......... 25.2/0.0020 844.9/1.21 379.6/0.38 631/0.82
Trestle (Bent 19).................... 30'' steel pipe......... Impact Install......... 65.8/0.014 2,205.0/3.72 990.7/1.47 2,512/4.44
Pier................................. 30'' steel pipe......... Impact Install......... 104.5/0.034 3,500.3/6.49 1,572.6/2.50 2,512/4.44
Gangway support piles (small boat 18'' steel pipe......... Impact Install......... 19.3/0.00058 644.8/0.17 289.7/0.049 631/0.16
floating dock).
Small Boat Floating Dock 36'' Steel Casing/Shaft Impact Install......... 35.5/0.002 1,189.5/0.45 534.4/0.12 3,415/2.14
with Rock Socket (Guide
Pile).
DTH Mono-Hammer........ 73/0.0084 2,444.5/1.21 1,098.2/0.42 13,594/3.31
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: dB = decibel; DTH = down-the-hole; dB RMS SPL = decibel root mean square sound pressure. level; dB SELcum = cumulative sound exposure level; m =
meter; PTS = Permanent Threshold Shift; km\2\ = square kilometer.
Table 8--Maximum Distances to Level A Harassment and Level B Harassment Thresholds for Continuous
[Vibratory Hammer/Rotary Drill]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A (PTS onset) harassment Level B
------------------------------------------------ (behavioral)
harassment
Maximum Maximum Maximum ---------------
distance to distance to distance to Maximum
198 dB SELcum 173 dB SELcum 201 dB SELcum distance 120
Structure Pile size and type Activity threshold(m)/ threshold(m)/ threshold(m)/ dB RMS SPL
area of area of area of (120 dB DTH)
harassment harassment harassment threshold (m)/
zone (km\2\) zone (km\2\) zone (km\2\) area of
harassment
zone (km\2\)
MF cetacean HF cetacean Phocid All Marine
Mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abandoned guide piles along bulkhead. 12'' steel pipe......... Vibratory Extract...... 0.3/0 5.3/0.000044 2.2/0.000008 2,514/1.26
Floating dock demolition (Timber 12'' timber............. Vibratory Extract...... 0.2/0 4/0.000025 1.7/0.000005 1,359/0.53
Guide Piles).
Bulkhead construction (Combination 18'' steel pipe......... Vibratory Install...... 1.8/0.000005 29.7/0.0014 12.2/0.00023 6,310/3.31
Pipe/Z-pile).
Steel sheet Z26-700..... Vibratory Install...... 0.7/0.000001 11.8/0.00022 4.9/0.000038 2,512/1.26
16'' steel pipe template Vibratory Install/ 1.1/0.000002 18.7/0.00055 7.7/0.000093 6,310/3.31
piles. Extract.
Trestle (Bents 1-18)................. 18'' steel pipe......... Vibratory Install...... 0.7/0.000002 11.8/0.00044 4.8/0.000072 6,310/8.53
18'' steel pipe hole.... Rotary Drill........... 0.0/0 0.6/0.000001 0.4/0.000001 1,848/2.98
16'' steel pipe template Vibratory Install/ 1.1/0.000004 18.7/0.0011 7.7/0.00019 6,310/8.53
piles. Extract.
Trestle (Bent 19).................... 30'' steel pipe......... Vibratory Install...... 2.0/0.000013 33.2/0.0034 13.7/0.00059 13,594/8.53
16'' steel pipe template Vibratory Install/ 1.1/0.000004 18.7/0.0011 7.7/0.00019 6,310/8.53
piles. Extract.
Pier................................. 30'' steel pipe......... Vibratory Install...... 3.2/0.000032 52.8/0.0087 21.7/0.0015 13,594/8.53
30'' hole............... Rotary Drill........... 0.0/0 0.6/0.000001 0.4/0.000001 1,848/2.98
16'' steel pipe template Vibratory Install/ 1.1/0.000004 18.7/0.0011 7.7/0.00019 6,310/8.53
piles. Extract.
Fender Piles......................... 16'' steel pipe......... Vibratory Install...... 0.9/0.000003 14.3/0.00064 5.9/0.00011 6,310/8.53
16'' steel pipe template Vibratory Install/ 1.1/0.000004 18.7/0.0011 7.7/0.00019 6,310/8.53
piles. Extract.
Gangway support piles (small boat 18'' steel pipe......... Vibratory Install...... 0.7/0.000001 11.8/0.00022 4.8/0.000036 6,310/3.31
floating dock).
Small Boat Floating Dock............. 36'' Steel Casing/Shaft Vibratory Install...... 5.2/0.000042 86.6/0.012 35.6/0.002 46,416/3.31
Guide Piles with Rock
Socket.
16'' steel pipe template Vibratory Install/ 1.1/0.000002 18.7/0.00055 7.7/0.000093 6,310/3.31
piles. Extract.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: dB = decibel; dB RMS SPL = decibel root mean square sound pressure level; dB SELcum = cumulative sound exposure level; m = meter; PTS = Permanent
Threshold Shift; km\2\ = square kilometer.
Concurrent Activities
Simultaneous use of two or three impact, vibratory, or DTH hammers,
or rotary drills, could occur (potential combinations described in
Table 1) and may result in increased sound source levels and harassment
zone sizes, given the proximity of the structure sites and the rules of
decibel addition (Table 9).
NMFS (2018b) handles overlapping sound fields created by the use of
more
[[Page 66152]]
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, rotary drill, and Level B harassment zones
for drilling with a DTH hammer (Table 9) 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 will strike at the same instant, and
therefore, the SPLs will not be adjusted regardless of the distance
between impact hammers. In this case, each impact hammer will 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 rules for
combining sound source levels generated during pile installation,
described in Table 9.
Table 9--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 Use zone for each pile
pile size and number size.
of strikes.
Vibratory, Vibratory Rotary drill, 0 or 1 dB................. Add 3 dB to the higher Add 3 dB to the higher
or DTH, DTH. source level. source level.
2 or 3 dB................. 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
source level. source level.
10 dB or more............. Add 0 dB to the higher Add 0 dB to the higher
source level. source level.
----------------------------------------------------------------------------------------------------------------
Note: The method is based on a method created by Washington State Department of Transportation (WSDOT 2020) and
has been updated and modified by NMFS.
When two continuous noise sources have overlapping sound fields,
there is potential for higher sound levels than for non-overlapping
sources. When two or more continuous noise sources 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 of decibel addition
(Table 9; NMFS 2021c).
For simultaneous use of three or more continuous sound sources,
NMFS first identifies the three overlapping sources with the highest
sound source level. Then, using the rules for combining sound source
levels generated during pile installation (Table 9), NMFS determines
the difference between the lower two source levels, and adds the
appropriate number of decibels to the higher source level of the two.
Then, NMFS calculates the difference between the newly calculated
source level and the highest source level of the three identified in
the first step, and again, adds the appropriate number of decibels to
the highest source level of the three.
For example, with overlapping isopleths from 24'', 36'', and 42''
diameter steel pipe piles with sound source levels of 161, 167, and 168
dB RMS respectively, NMFS would first calculate the difference between
the 24'' and 36'' source levels (167 dB-161 dB = 6 dB. Then, given that
the difference is 6 dB, as described in Table 9, NMFS would then add 1
dB to the highest of the two sound source levels (167 dB), for a
combined noise level of 168 dB. Next, NMFS calculates the difference
between the newly calculated 168 dB and the sound source level of the
42'' steel pile (168 dB). Since 168 dB-168 dB = 0 dB, 3 dB is added to
the highest value (168 dB + 3 dB = 171 dB). Therefore, for the
combination of 24'', 36'', and 42'' steel pipe piles, zones would be
calculated using a combined sound source level of 171 dB.
If an impact hammer and a vibratory hammer are used concurrently,
the largest Level B harassment zone generated by either hammer would
apply, and the Level A harassment zone generated by the impact hammer
would apply. Simultaneous use of two or more impact hammers does not
require source level additions as it is unlikely that two hammers would
strike at the same exact instant. Thus, sound source levels are not
adjusted regardless of distance, and the zones for each individual
activity apply.
For activity combinations that do require sound source level
adjustment, Table 10 shows the revised proxy source levels for
concurrent activities based upon the rules for combining sound source
levels generated during pile installation, described in Table 9.
Resulting Level A harassment and Level B harassment zones for
concurrent activities are summarized in Table 11. The maximum Level A
harassment isopleth would be 2,444.5 m for high-frequency cetaceans
generated by concurrent use of two vibratory pile drivers and DTH mono-
hammer during installation of 36'' shafts for the small boat floating
dock (Table 11). The maximum Level B harassment isopleth would be
54,117 m for the concurrent use of DTH mono-hammer and two vibratory
pile drivers for installation of 36'' shafts for the small boat
floating dock (Table 11).
Table 10--Proxy Values for Simultaneous Use of Non-Impulsive Sources
------------------------------------------------------------------------
Structure Activity and proxy New proxy
------------------------------------------------------------------------
Bulkhead.................... Vibratory Install 16-inch 165 dB RMS
steel pipe piles--162 dB RMS.
Vibratory Install 18-inch
steel pipe piles--162 dB RMS.
Vibratory Install 18-inch 168 dB RMS
steel pipe piles--162 dB.
DTH Install 18-inch steel pipe
piles--167 dB.
------------------------------------------------------------------------
[[Page 66153]]
Bulkhead and Trestle........ Vibratory Install/extract 16- 166 dB RMS
inch steel pipe piles--162 dB
RMS.
Vibratory Install Z26-700
sheet piles--156 dB RMS.
Vibratory Install 18-inch
steel pipe piles--162 dB RMS.
Vibratory Install/extract 16- 163 dB RMS
inch steel pipe piles--162 dB
RMS.
Vibratory Install Z26-700
sheet piles--156 dB RMS.
Rotary Drill 18-inch steel
pipe piles--154 dB RMS.
------------------------------------------------------------------------
Pier........................ Vibratory Install/extract 16- 168 dB RMS
inch steel pipe piles--162 dB
RMS.
Vibratory Install 30-inch
steel pipe piles--167 dB RMS.
Vibratory Install/extract 16- 163 dB RMS
inch steel pipe piles--162 dB
RMS.
Rotary Drill 30-inch steel
pipe piles--154 dB RMS.
------------------------------------------------------------------------
Pier Fender Piles and Small Vibratory Install/extract 16- 165 dB RMS
Boat Floating Dock. inch steel pipe piles--162 dB
RMS.
Vibratory Install 18-inch
steel pipe piles--162 dB RMS.
Vibratory Install/extract 16- 175 dB RMs
inch steel pipe piles--162 dB
RMS.
Vibratory Install 36-inch
steel pipe piles--175 dB RMS.
Vibratory Install 36-inch 176 dB
steel casing--175 dB.
DTH Install 36-inch steel
casing--167 dB.
------------------------------------------------------------------------
Table 11--Maximum Distances to Level A and Level B Harassment Thresholds for Concurrent Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A (PTS onset) harassment Level B
------------------------------------------------------ (behavioral)
harassment
Maximum distance Maximum distance Maximum distance ----------------
to continuous to continuous to continuous Maximum
Total 198 dB SELcum; 173 dB SELcum; 201 dB SELcum; distance 120 dB
Structure Pile sizes and Activity production DTH 185 dB DTH 155 dB DTH 185 dB RMS SPL
type days SELcum SELcum SELcum threshold (m)/
thresholds (m)/ thresholds (m)/ thresholds (m)/ area of
area of Area of area of harassment zone
harassment zone harassment zone harassment zone (km\2\)
(km\2\) (km\2\) (km\2\) (continuous and
DTH)
MF cetacean..... HF cetacean..... Phocid..........
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bulkhead..................... Install of 16- Install/Extract 15 3.7/0.000021.... 61.6/0.0060..... 25.3/0.001...... 10,000/3.31
inch and 18- using two
inch steel pipe Vibratory Pile
piles. Drivers.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Install of 18- Install using 12 Vibratory: 1.8/ Vibratory: 29.7/ Vibratory: 12.2/ 15,848.93/3.31
inch steel pile. two Vibratory 0.000005 DTH: 0.0014 DTH: 0.00023 DTH:
Pile Drivers 4.6/0.000033. 154.2/0.028. 69.3/0.0075.
and DTH mono-
hammer.
Bulkhead and Trestle......... Install of 16- Install/Extract 15 4.1/0.000026.... 68.3/0.0073..... 28.1/0.0012..... 10,000/3.31
inch and 18- using three
inch steel pipe Vibratory Pile
and Z26-700 Drivers.
steel sheet
piles.
Install/Extract 14 2.9/0.000013.... 47.8/0.0036..... 19.7/0.00061.... 7,356/3.31
using two
Vibratory Pile
Drivers and a
Rotary Drill.
Pier......................... Install of 16- Install/Extract 30 5.9/0.00011..... 97.6/0.030...... 40.1/0.0050..... 15,849/8.53
and 30-inch using two
steel pipe. Vibratory Pile
Drivers.
Install/Extract 27 2.0/0.0031...... 33.1/0.0034..... 13.6/0.00058.... 7,356/8.53
using a
vibratory pile
driver and
rotary drill.
Pier Fender Piles and Gangway Install of 16- Install/Extract 17 2.3/0.000017.... 38.8/0.0047..... 16.0/0.0008..... 10,000/8.53
Support for Small Boat and 18-inch using two
Floating Dock. steel pipe. Vibratory Pile
Drivers.
Install of 16- Install using 20 9.6/0.00029..... 159.5/0.080..... 65.6/0.013...... 46,416/8.53
inch steel pipe two Vibratory
and 36-inch Pile Drivers.
shafts.
[[Page 66154]]
Install of 36- Install using 2 Vibratory: 5.2/ Vibratory: 86.6/ Vibratory: 35.6/ DTH: 54,117/
inch shafts. two Vibratory 0.000042 DTH: 0.012 DTH: 0.002 DTH: 8.53
Pile Drivers 73/0.0084. 2,444.5/1.21. 1,098.2/0.42.
and DTH mono-
hammer.
--------------------------------------------------------------------------------------------------------------------------------------------------------
dB RMS SPL = decibel root mean square sound pressure level; dB SELcum = cumulative sound exposure level; m = meter; PTS = Permanent Threshold Shift;
km\2\ = square kilometer.
The Level B harassment zones in Table 11 were calculated based upon
the adjusted source levels for simultaneous construction activities
(Table 10). OMAO has not proposed any scenarios for concurrent work in
which the Level A harassment isopleths would need to be adjusted from
that calculated for single sources. Regarding implications for Level A
harassment zones when multiple vibratory hammers, or vibratory hammers
and rotary drills, are operating concurrently, given the small size of
the estimated Level A harassment isopleths for all hearing groups
during vibratory pile driving, the zones of any two hammers or hammer
and drill are not 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 vibratory
hammers are operating concurrently with a DTH hammer, combining
isopleths for these sources is difficult for a variety of reasons.
First, vibratory pile driving relies upon non-impulsive PTS thresholds,
while DTH hammers use impulsive thresholds. Second, vibratory pile
driving accounts 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 implications for impact hammers used in combination with
a vibratory hammer or DTH hammer, the likelihood of these multiple
sources' isopleths completely overlapping 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
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information that
will inform the take calculations. Potential exposures to construction
noise for each acoustic threshold were estimated using marine mammal
density estimates (N) from the Navy Marine Species Density Database
(NMSDD) (Navy, 2017a). OMAO evaluated data reflecting monthly densities
of each species to determine minimum, maximum, and average annual
densities within Narragansett Bay. Table 12 summarizes the average
annual densities of species that may be impacted by the proposed
construction activities, with the exception of harbor seals as the
density value for this species in the table represents the maximum
density value for seals.
Table 12--Average Densities by Species Used in Exposure Analysis
------------------------------------------------------------------------
Average density
in project area
Species (species per
km\2\)
------------------------------------------------------------------------
Atlantic White-sided Dolphin......................... 0.003
Common Dolphin....................................... 0.011
Harbor Porpoise...................................... 0.012
Harbor Seal.......................................... 0.623
Gray Seal............................................ 0.131
Harp Seal............................................ 0.05
Hooded Seal.......................................... 0.001
------------------------------------------------------------------------
The NMSDD models reflect densities for seals as a guild due to
difficulty in distinguishing these species at sea. Harbor seal is
expected to be the most common pinniped in Narragansett Bay with year-
round occurrence (Kenney and Vigness-Raposa, 2010). Therefore, OMAO
used the maximum density for the seal guild for harbor seal. Gray seals
are the second most common seal to be observed in Rhode Island waters
and, based on stranding records, are commonly observed during the
spring to early summer and occasionally observed during other months of
the year (Kenney, 2020). Therefore, the average density for the seal
guild was used for gray seal occurrence in Narragansett Bay. Minimum
densities for the seal guild were used for harp seal and hooded seals
as they are considered occasional visitors in Narragansett Bay
[[Page 66155]]
but are rare in comparison to harbor and gray seals (Kenney, 2015).
NMFS has carefully reviewed and concurs with the use of these densities
proposed by OMAO.
Take Estimation
Here we describe how the information provided above is synthesized
to produce a quantitative estimate of the take that is reasonably
likely to occur and proposed for authorization.
For each species, OMAO multiplied the average annual density by the
largest ensonified area (Tables 7, 8, 11) and the maximum days of
activity (Tables 7, 8, 11) (take estimate = N x ensonified area x days
of pile driving) in order to calculate estimated take by Level A
harassment and Level B harassment. OMAO used the pile type, size, and
construction method that produce the largest isopleth to estimate
exposure of marine mammals to noise impacts. The exposure estimate was
rounded to the nearest whole number at the end of the calculation.
Table 13 shows the total estimated number of takes for each species by
Level A harassment and Level B harassment for individual and concurrent
activities as well as estimated take as a percent of stock abundance.
Estimated take by activity type for individual and concurrent equipment
use for each species is shown in Tables 6-12 through 6-17 in the
application. OMAO is requesting take by Level A harassment of 4 species
(harbor porpoise, harbor seal, gray seal, and harp seal) incidental to
construction activities using one equipment type. In addition, OMAO is
requesting one take of harbor seals by Level A harassment during
concurrent use of a DTH mono-hammer and two vibratory hammers for
installation of 36'' shafts for the small boat floating dock.
To account for group size, OMAO conservatively increased the
estimated take by Level B harassment from 9 to 16 Atlantic white-sided
dolphins, as the calculated take was less than the documented average
group size (NUWC, 2017). NMFS agrees with this approach, and is
proposing to authorize 16 takes by Level B harassment of Atlantic
white-sided dolphins. The species density for the hooded seal was too
low to result in any calculated estimated takes. In order to be
conservative, OMAO requested, and NMFS is proposing to authorize, 1
take by Level B harassment of hooded seals for each month of
construction activity when this species may occur in the project area.
Hooded seals may occur in the project area from January through May
which is a total of 5 months. Therefore, OMAO is requesting, and NMFS
is proposing to authorize, 5 takes by Level B harassment of hooded
seals for individual construction activities and 5 takes by Level B
harassment of hooded seals for concurrent construction activities for a
total of 10 takes by Level B harassment of hooded seals.
Table 13--Total Estimated Take by Level A harassment and Level B Harassment for Individual and Concurrent Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Individual activities Concurrent activities
---------------------------------------------------------------- Total
Species Level A Level B Level A Level B requested % of stock
harassment harassment harassment harassment take
--------------------------------------------------------------------------------------------------------------------------------------------------------
Atlantic white-sided dolphin............................ 0 6 0 3 16 \1\ 0.2
Short-beaked common dolphin............................. 0 26 0 13 39 0.2
Harbor Porpoise......................................... 2 27 0 13 42 0.044
Harbor Seal............................................. 55 1,478 1 589 2,123 3.46
Gray Seal............................................... 11 312 0 125 448 1.64
Harp Seal............................................... 4 117 0 47 168 0.002
Hooded Seal............................................. 0 \2\ 5 0 \2\ 5 10 0.002
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Requested take has been increased to mean group size (NUWC, 2017). Mean group size was not used for those take estimates that exceeded the mean
group size.
\2\ OMAO is conservatively requesting 1 take by Level B harassment of hooded seal per month of construction when this species may occur in the project
area (January through May).
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 (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks, and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost and impact on
operations.
NMFS proposes the following mitigation measures be implemented for
OMAO's pile installation and removal activities.
Shutdown Zones
OMAO will establish shutdown zones for all pile driving activities.
The purpose of a shutdown zone is generally to define an area within
which shutdown of the activity would occur upon sighting of a marine
mammal (or in anticipation of an animal entering the defined area).
Shutdown zones would be based upon the Level A harassment zone for each
pile size/type and driving method, as shown in Table 14. If the
[[Page 66156]]
Level A harassment zone is too large to monitor, the shutdown zone
would be limited to a radial distance of 200 m from the acoustic source
(86 FR 71162, December 15, 2021; 87 FR 19886, April 6, 2022). For
example, the largest Level A harassment zone for high-frequency
cetaceans extends approximately 2,444,5 m from the source during DTH
mono-hammer excavation while installing the 36-in steel shafts for the
small boat floating dock (Table 7). OMAO plans to maintain maximum
shutdown zone of 200 m for that activity, consistent with prior
projects in the area (87 FR 11860, March 2, 2022).
A minimum shutdown zone of 10 m would be applied for all in-water
construction activities if the Level A harassment zone is less than 10
m (i.e., vibratory pile driving, drilling). The 10 m shutdown zone
would also serve to protect marine mammals from collisions with project
vessels during pile driving and other construction activities, such as
barge positioning or drilling. If an activity is delayed or halted due
to the presence of a marine mammal, the activity may not commence or
resume until either the animal has voluntarily exited and been visually
confirmed beyond the shutdown zone indicated in Table 14 or 15 minutes
have passed without re-detection of the animal. Construction activities
must be halted upon observation of a species for which incidental take
is not authorized or a species for which incidental take has been
authorized but the authorized number of takes has been met entering or
within the harassment zone.
If a marine mammal enters the Level B harassment zone, in-water
work would proceed and PSOs would document the marine mammal's presence
and behavior.
Table 14--Shutdown Zones and Level B Harassment Zones by Activity
----------------------------------------------------------------------------------------------------------------
Shutdown zone (m) Level B harassment
-------------------------------- zone (m)
Pile type/size Driving method ----------------------
Cetaceans Pinnipeds All marine mammals
----------------------------------------------------------------------------------------------------------------
12'' steel pipe................... Vibratory extraction. 10 10 2,600.
12'' timber....................... Vibratory extraction. 15 10 3,500.
16'' steel pipe................... Vibratory install/ 20 10 6,400.
extract.
18'' steel pipe................... Impact install....... \1\ 200 \1\ 200 640.
Vibratory install.... 30 15 6,400.
DTH Mono-hammer...... \1\ 200 \1\ 200 Maximum harassment
zone.\2\
Rotary drilling 18'' 10 10 1,900.
holes.
Z26-700 steel sheets.............. Vibratory install.... 15 10 2,600.
30'' steel pipe................... Impact install....... \1\ 200 \1\ 200 2,600.
Vibratory install.... 55 25 Maximum harassment
zone.\2\
30'' steel pipe................... Rotary drilling...... 10 10 1,900.
36'' steel pipe................... Impact install....... \1\ 200 \1\ 200 3,400.
Vibratory install.... 90 40 Maximum harassment
zone \2\
36'' shafts....................... DTH Mono-hammer...... \1\ 200 \1\ 200 Maximum harassment
zone.\2\
----------------------------------------------------------------------------------------------------------------
\1\ Distance to shutdown zone distances implemented for other similar projects in the region (NAVFAC, 2019).
\2\ Harassment zone would be truncated due to the presence of intersecting land masses and would encompass a
maximum area of 3.31 km\2\.
Protected Species Observers
The placement of protected species observers (PSOs) during all
construction activities (described in the Proposed Monitoring and
Reporting section) would ensure that the entire shutdown zone is
visible. Should environmental conditions deteriorate such that the
entire shutdown zone would not be visible (e.g., fog, heavy rain), pile
driving would be delayed until the PSO is confident marine mammals
within the shutdown zone could be detected.
Monitoring for Level A Harassment and Level B Harassment
PSOs would monitor the full shutdown zones and the remaining Level
A harassment and the Level B harassment zones to the extent
practicable. Monitoring zones provide utility for observing by
establishing monitoring protocols for areas adjacent to the shutdown
zones. Monitoring zones enable observers to be aware of and communicate
the presence of marine mammals in the project areas outside the
shutdown zones and thus prepare for a potential cessation of activity
should the animal enter the shutdown zone.
Pre-Activity Monitoring
Prior to the start of daily in-water construction activity, or
whenever a break in pile driving of 30 minutes or longer occurs, PSOs
would observe the shutdown, Level A harassment, and Level B harassment
for a period of 30 minutes. Pile driving may commence following 30
minutes of observation when the determination is made that the shutdown
zones are clear of marine mammals. If a marine mammal is observed
within the shutdown zones listed in Table 14, construction activity
would be delayed until the animal has voluntarily exited and been
visually confirmed beyond the shutdown zone indicated in Table 14 or
has not been observed for 15 minutes. When a marine mammal for which
Level B harassment take is authorized is present in the Level B
harassment zone, activities would begin and Level B harassment take
would be recorded. A determination that the shutdown zone is clear must
be made during a period of good visibility (i.e., the entire shutdown
zone and surrounding waters are visible). If the shutdown zone is
obscured by fog or poor lighting conditions, in-water construction
activity would not be initiated until the entire shutdown zone is
visible.
Soft-Start
Soft-start procedures are used to provide additional protection to
marine mammals by providing warning and/or giving marine mammals a
chance to leave the area prior to the hammer operating at full
capacity. For impact pile driving, contractors would be required to
provide an initial set of three strikes from the hammer at reduced
energy, followed by a 30-second waiting period, then two subsequent
reduced-energy strike sets. Soft start would be implemented at the
start of each day's impact pile driving and at any time following
cessation of impact pile driving for a period of 30 minutes or longer.
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the
[[Page 66157]]
proposed mitigation measures provide the means of effecting the least
practicable impact on the affected species or stocks and their habitat,
paying particular attention to rookeries, mating grounds, and areas of
similar significance.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the action; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and,
<bullet> Mitigation and monitoring effectiveness.
Visual Monitoring
Marine mammal monitoring during in-water construction activities
would be conducted by PSOs meeting NMFS' standards and in a manner
consistent with the following:
<bullet> Independent PSOs (i.e., employees of the entity conducting
construction activities may not serve as PSOs) who have no other
assigned tasks during monitoring periods would be used;
<bullet> At least one PSO would have prior experience performing
the duties of a PSO during construction activity pursuant to a NMFS-
issued incidental take authorization;
<bullet> Other PSOs may substitute education (degree in biological
science or related field) or training for experience; and
<bullet> Where a team of three or more PSOs is required, a lead
observer or monitoring coordinator would be designated. The lead
observer would be required to have prior experience working as a marine
mammal observer during construction.
PSOs would have the following additional qualifications:
<bullet> Ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
<bullet> Writing skills sufficient to prepare a report of
observations including but not limited to the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was not implemented when required);
and marine mammal behavior; and
<bullet> Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary.
Visual monitoring would be conducted by a minimum of two trained
PSOs positioned at suitable vantage points. Any activity for which the
Level B harassment isopleth would exceed 1,900 meters would require a
minimum of three PSOs to effectively monitor the entire Level B
harassment zone. PSOs would likely be located on Gould Island South,
Gould Island Pier, Coddington Point, Bishop Rock, Breakwater, or Taylor
Point as shown in Figure 11-1 in the application. All PSOs would have
access to high-quality binoculars, range finders to monitor distances,
and a compass to record bearing to animals as well as radios or cells
phones for maintaining contact with work crews.
Monitoring would be conducted 30 minutes before, during, and 30
minutes after all in water construction activities. In addition, PSOs
would record all incidents of marine mammal occurrence, regardless of
distance from activity, and would document any behavioral reactions in
concert with distance from piles being driven or removed. Pile driving
activities include the time to install or remove a single pile or
series of piles, as long as the time elapsed between uses of the pile
driving equipment is no more than 30 minutes.
OMAO and the Navy shall conduct briefings between construction
supervisors and crews, PSOs, OMAO and Navy staff prior to the start of
all pile driving activities and when new personnel join the work. These
briefings would explain responsibilities, communication procedures,
marine mammal monitoring protocol, and operational procedures.
Hydro-Acoustic Monitoring
OMAO would implement in situ acoustic monitoring efforts to measure
SPLs from in-water construction activities by collecting and evaluating
acoustic sound recording levels during activities. Stationary
hydrophones would be placed 33 ft (10 m) from the noise source, in
accordance with NMFS' most recent guidance for the collection of source
levels. If there is the potential for Level A harassment, a second
monitoring location would be set up at an intermediate distance between
cetacean/phocid shutdown zones and Level A harassment zones.
Hydrophones would be deployed with a static line from a stationary
vessel. Locations of hydro-acoustic recordings would be collected via
GPS. A depth sounder and/or weighted tape measure would be used to
determine the depth of the water. The hydrophone would be attached to a
weighted nylon cord or chain to maintain a constant depth and distance
from the pile area. The nylon cord or chain would be attached to a
float or tied to a static line.
Each hydrophone would be calibrated at the start of each action and
would be checked frequently to the applicable standards of the
hydrophone manufacturer. Environmental data would be collected,
including but not limited to, the following: wind speed and direction,
air temperature, humidity, surface water temperature, water depth, wave
height, weather conditions, and other factors that could
[[Page 66158]]
contribute to influencing the airborne and underwater sound levels
(e.g., aircraft, boats, etc.). The chief inspector would supply the
acoustics specialist with the substrate composition, hammer or drill
model and size, hammer or drill energy settings and any changes to
those settings during the piles being monitored, depth of the pile
being driven or shaft excavated, and blows per foot for the piles
monitored. For acoustically monitored piles and shafts, data from the
monitoring locations would be post-processed to obtain the following
sound measures:
<bullet> Maximum peak pressure level recorded for all the strikes
associated with each pile or shaft, expressed in dB re 1 [mu]Pa. For
pile driving and DTH mono-hammer excavation, this maximum value would
originate from the phase of pile driving/drilling during which hammer/
drill energy was also at maximum (referred to as Level 4);
<bullet> From all the strikes associated with each pile occurring
during the Level 4 phase these additional measures would be made:
(1) mean, median, minimum, and maximum RMS pressure level in [dB re
1 [mu]Pa];
(2) mean duration of a pile strike (based on the 90 percent energy
criterion);
(3) number of hammer strikes;
(4) mean, median, minimum, and maximum single strike SEL in [dB re
[mu]Pa2 s];
<bullet> Cumulative SEL as defined by the mean single strike SEL +
10*log10 (number of hammer strikes) in [dB re [mu]Pa2 s];
<bullet> Median integration time used to calculate SPL RMS;
<bullet> A frequency spectrum (pressure spectral density) in [dB re
[mu]Pa2 per Hertz {Hz{time} ] based on the average of up to eight
successive strikes with similar sound. Spectral resolution would be 1
Hz, and the spectrum would cover nominal range from 7 Hz to 20 kHz;
<bullet> Finally, the cumulative SEL would be computed from all the
strikes associated with each pile occurring during all phases, i.e.,
soft-start, Level 1 to Level 4. This measure is defined as the sum of
all single strike SEL values. The sum is taken of the antilog, with
log10 taken of result to express in [dB re [mu]Pa2 s].
Hydro-acoustic monitoring would be conducted for at least 10% and
up to 10 of each different pile type for each method of installation as
shown in Table 13-1 in the application All acoustic data would be
analyzed after the project period for pile driving, rotary drilling,
and DTH mono-hammer excavation events to confirm SPLs and rate of
transmission loss for each construction activity.
Reporting
OMAO would submit a draft marine mammal monitoring report to NMFS
within 90 days after the completion of pile driving activities, or 60
days prior to a requested date of issuance of any future IHAs for the
project, or other projects at the same location, whichever comes first.
The marine mammal monitoring report would include an overall
description of work completed, a narrative regarding marine mammal
sightings, and associated PSO data sheets. Specifically, the report
would include:
<bullet> Dates and times (begin and end) of all marine mammal
monitoring;
<bullet> Construction activities occurring during each daily
observation period, including:
(1) The number and type of piles that were driven and the method
(e.g., impact, vibratory, down-the-hole, etc.);
(2) Total duration of time for each pile (vibratory driving) number
of strikes for each pile (impact driving); and
(3) For down-the-hole drilling, duration of operation for both
impulsive and non-pulse components.
<bullet> PSO locations during marine mammal monitoring; and
<bullet> Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and any other relevant
weather conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance.
For each observation of a marine mammal, the following would be
reported:
<bullet> Name of PSO who sighted the animal(s) and PSO location and
activity at time of sighting;
<bullet> Time of sighting;
<bullet> Identification of the animal(s) (e.g., genus/species,
lowest possible taxonomic level, or unidentified), PSO confidence in
identification, and the composition of the group if there is a mix of
species;
<bullet> Distance and location of each observed marine mammal
relative to the pile being driven or hole being drilled for each
sighting;
<bullet> Estimated number of animals (min/max/best estimate);
<bullet> Estimated number of animals by cohort (adults, juveniles,
neonates, group composition, etc.);
<bullet> Animal's closest point of approach and amount of time
spent in harassment zone;
<bullet> Description of any marine mammal behavioral observations
(e.g., observed behaviors such as feeding or traveling), including an
assessment of behavioral responses thought to have resulted from the
activity (e.g., no response or changes in behavioral state such as
ceasing feeding, changing direction, flushing, or breaching);
<bullet> Number of marine mammals detected within the harassment
zones, by species; and
<bullet> Detailed information about implementation of any
mitigation (e.g., shutdowns and delays), a description of specified
actions that ensued, and resulting changes in behavior of the
animal(s), if any.
If no comments are received from NMFS within 30 days, the draft
report would constitute the final reports. If comments are received, a
final report addressing NMFS' comments would be required to be
submitted within 30 days after receipt of comments. All PSO datasheets
and/or raw sighting data would be submitted with the draft marine
mammal report.
In the event that personnel involved in the construction activities
discover an injured or dead marine mammal, OMAO would report the
incident to the Office of Protected Resources (OPR)
(<a href="/cdn-cgi/l/email-protection#8fdfdda1c6dbdfa1c2e0e1e6fbe0fde6e1e8ddeaffe0fdfbfccfe1e0eeeea1e8"><span class="__cf_email__" data-cfemail="6333314d2a37334d2e0c0d0a170c110a0d043106130c111710230d0c02024d04">[email protected]</span></a>ov), NMFS and to the Northeast Region
(GARFO) regional stranding coordinator as soon as feasible. If the
death or injury was clearly caused by the specified activity, OMAO
would immediately cease the specified activities until NMFS is able to
review the circumstances of the incident and determine what, if any,
additional measures are appropriate to ensure compliance with the terms
of the IHAs. OMAO would not resume their activities until notified by
NMFS.
The report would include the following information:
1. Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
2. Species identification (if known) or description of the
animal(s) involved;
3. Condition of the animal(s) (including carcass condition if the
animal is dead);
4. Observed behaviors of the animal(s), if alive;
5. If available, photographs or video footage of the animal(s); and
6. General circumstances under which the animal was discovered.
OMAO would also provide a hydro-acoustic monitoring report based
upon hydro-acoustic monitoring conducted during construction
activities. The hydro-acoustic monitoring report would include:
[[Page 66159]]
<bullet> Hydrophone equipment and methods: recording device,
sampling rate, distance (meter) from the pile where recordings were
made; depth of water and recording device(s);
<bullet> Type and size of pile being driven, substrate type, method
of driving during recordings (e.g., hammer model and energy), and total
pile driving duration;
<bullet> Whether a sound attenuation device is used and, if so, a
detailed description of the device used and the duration of its use per
pile;
<bullet> For impact pile driving and/or DTH mono-hammer excavation
(per pile): Number of strikes and strike rate; depth of substrate to
penetrate; pulse duration and mean, median, and maximum sound levels
(dB re: 1 [mu]Pa): root mean square sound pressure level
(SPL<INF>rms</INF>); cumulative sound exposure level
(SEL<INF>cum</INF>), peak sound pressure level (SPL<INF>peak</INF>),
and single-strike sound exposure level (SEL<INF>s-s</INF>);
<bullet> For vibratory driving/removal and/or DTH mono-hammer
excavation (per pile): Duration of driving per pile; mean, median, and
maximum sound levels (dB re: 1 [mu]Pa): root mean square sound pressure
level (SPL<INF>rms</INF>), cumulative sound exposure level
(SEL<INF>cum</INF>) (and timeframe over which the sound is averaged);
<bullet> One-third octave band spectrum and power spectral density
plot; and
<bullet> General daily site conditions, including date and time of
activities, water conditions (e.g., sea state, tidal state), and
weather conditions (e.g., percent cover, visibility.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the majority of our analysis applies to all
the species listed in Table 3, given that many of the anticipated
effects of this project on different marine mammal stocks are expected
to be relatively similar in nature. Where there are meaningful
differences between species or stocks, or groups of species, in
anticipated individual responses to activities, impact of expected take
on the population due to differences in population status, or impacts
on habitat, they are described independently in the analysis below.
Pile driving activities associated with the OMAO vessel relocation
project have the potential to disturb or displace marine mammals.
Specifically, the project activities may result in take, in the form of
Level B harassment, and for harbor porpoise, harbor seal, gray seal,
and harp seal, Level A harassment, from underwater sounds generated
from pile driving and removal, DTH, and rotary drilling. Potential
takes could occur if individuals are present in zones ensonified above
the thresholds for Level B harassment, identified above, when these
activities are underway.
No serious injury or mortality would be expected, even in the
absence of required mitigation measures, given the nature of the
activities. Further, no take by Level A harassment is anticipated for
Atlantic white-sided dolphins, short-beaked common dolphins, and harp
seals due to the application of planned mitigation measures, such as
shutdown zones that encompass the Level A harassment zones for these
species. The potential for harassment would be minimized through the
construction method and the implementation of the planned mitigation
measures (see Proposed Mitigation section).
Take by Level A harassment is proposed for 4 species (harbor
porpoise, harbor seal, gray seal, and harp seal) as the Level A
harassment zones exceed the size of the shutdown zones for specific
construction scenarios. Therefore, there is the possibility that an
animal could enter a Level A harassment zone without being detected,
and remain within that zone for a duration long enough to incur PTS.
Any take by Level A harassment is expected to arise from, at most, a
small degree of PTS (i.e., minor degradation of hearing capabilities
within regions of hearing that align most completely with the energy
produced by impact pile driving such as the low-frequency region below
2 kHz), not severe hearing impairment or impairment within the ranges
of greatest hearing sensitivity. Animals would need to be exposed to
higher levels and/or longer duration than are expected to occur here in
order to incur any more than a small degree of PTS.
Further, the amount of take proposed for authorization by Level A
harassment is very low for all marine mammal stocks and species. For
three species, Atlantic white-sided dolphin, short-beaked common
dolphin, and harp seal, NMFS anticipates and proposes to authorize no
Level A harassment take over the duration of OMAO's planned activities;
for the other four stocks, NMFS proposes to authorize no more than 56
takes by Level A harassment for any stock. If hearing impairment
occurs, it is most likely that the affected animal would lose only a
few decibels in its hearing sensitivity. Due to the small degree
anticipated, any PTS potential incurred would not be expected to affect
the reproductive success or survival of any individuals, much less
result in adverse impacts on the species or stock.
Additionally, some subset of the individuals that are behaviorally
harassed could also simultaneously incur some small degree of TTS for a
short duration of time. However, since the hearing sensitivity of
individuals that incur TTS is expected to recover completely within
minutes to hours, it is unlikely that the brief hearing impairment
would affect the individual's long-term ability to forage and
communicate with conspecifics, and would therefore not likely impact
reproduction or survival of any individual marine mammal, let alone
adversely affect rates of recruitment or survival of the species or
stock.
As described above, NMFS expects that marine mammals would likely
move away from an aversive stimulus, especially at levels that would be
expected to result in PTS, given sufficient notice through use of soft
start. OMAO would also shut down pile driving activities if marine
mammals enter the shutdown zones (see Table 14) further minimizing the
likelihood and degree of PTS that would be incurred.
Effects on individuals that are taken by Level B harassment in the
form of
[[Page 66160]]
behavioral disruption, on the basis of reports in the literature as
well as monitoring from other similar activities, would likely be
limited to reactions such as avoidance, increased swimming speeds,
increased surfacing time, or decreased foraging (if such activity were
occurring) (e.g., Thorson and Reyff 2006). Most likely, individuals
would simply move away from the sound source and temporarily avoid the
area where pile driving is occurring. If sound produced by project
activities is sufficiently disturbing, animals are likely to simply
avoid the area while the activities are occurring. We expect that any
avoidance of the project areas by marine mammals would be temporary in
nature and that any marine mammals that avoid the project areas during
construction would not be permanently displaced. Short-term avoidance
of the project areas and energetic impacts of interrupted foraging or
other important behaviors is unlikely to affect the reproduction or
survival of individual marine mammals, and the effects of behavioral
disturbance on individuals is not likely to accrue in a manner that
would affect the rates of recruitment or survival of any affected
stock.
Since June 2022, an Unusual Mortality Event (UME) has been declared
for Northeast pinnipeds in which elevated numbers of sick and dead
harbor seals and gray seals have been documented along the southern and
central coast of Maine (NOAA Fisheries, 2022). As of October 18, 2022,
the date of writing of this notice, 22 grays seals and 230 harbor seals
have stranded. However, we do not expect takes that may be authorized
under this rule to exacerbate or compound upon these ongoing UMEs. As
noted previously, no injury, serious injury, or mortality is expected
or will be authorized, and takes of harbor seal and gray seal will be
reduced to the level of least practicable adverse impact through the
incorporation of the required mitigation measures. For the WNA stock of
gray seal, the estimated U.S. stock abundance is 27,300 an
[…truncated; see source link]Indexed from Federal Register on November 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.