Notice2025-15014
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay and the Atlantic Ocean
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 7, 2025
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from Transcontinental Gas Pipe Line Company, LLC (Transco), a subsidiary of Williams Partners L.P., for authorization to take marine mammals incidental to the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay, and the Atlantic Ocean. 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 90 Issue 150 (Thursday, August 7, 2025)</title>
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[Federal Register Volume 90, Number 150 (Thursday, August 7, 2025)]
[Notices]
[Pages 38104-38132]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-15014]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF001]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Northeast Supply Enhancement
Project in Raritan Bay, Lower New York Bay and the Atlantic Ocean
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 Transcontinental Gas Pipe
Line Company, LLC (Transco), a subsidiary of Williams Partners L.P.,
for authorization to take marine mammals incidental to the Northeast
Supply Enhancement Project in Raritan Bay, Lower New York Bay, and the
Atlantic Ocean. 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
September 8, 2025.
ADDRESSES: Comments should be addressed to 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#91d8c5c1bfd7fdf4fcf8fff6d1fffef0f0bff6fee7"><span class="__cf_email__" data-cfemail="3b726f6b157d575e5652555c7b55545a5a155c544d">[email protected]</span></a>.
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 below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Kate Fleming, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs 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 IHA 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
[[Page 38105]]
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
(collectively referred to as ``mitigation''); and requirements
pertaining to the monitoring and reporting of the takings. The
definitions of all applicable MMPA statutory terms used above are
included in the relevant sections below and can be found in section 3
of the MMPA (16 U.S.C. 1362) and NMFS regulations at 50 CFR 216.103.
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 NAO 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.
Summary of Request
On May 30, 2025, NMFS received a request from Transco for an IHA to
take marine mammals incidental to Northeast Supply Enhancement Project
in Raritan Bay, Lower New York Bay and the Atlantic Ocean (in the New
York Bight). During NMFS' application review, Transco indicated that
two hammers at the same location may operate at the same time and
provided scenarios for simultaneous pile driving on July 11, 2025,
which necessitated additional analysis. Following NMFS' review of the
application and subsequent discussions between NMFS and Transco, the
application was deemed adequate and complete on July 29, 2025.
Transco's initial request was for authorization of take of 14 species
of marine mammals, by Level B harassment and, for a subset of 4 of
these species, Level A harassment. Following analysis, NMFS is
proposing to authorize take of 15 species of marine mammals, by Level B
harassment and, for a subset of 7 of these species, Level A harassment.
Neither Transco nor NMFS expect serious injury or mortality to result
from this activity and, therefore, an IHA is appropriate.
NMFS previously issued an IHA to Transco for the same project (85
FR 15125, March 17, 2020) as updated in the 2025 application. No work
was conducted under the 2020 IHA. NMFS also previously issued a
separate IHA to Transco for its Lower New York Bay Lateral Maintenance
(LNYBL) that occurred in the same region (89 FR 20170, March 21,
2024).and). Transco conducted all required monitoring and reporting
under the 2024 IHA, and information regarding Transco's monitoring
results may be found in the Potential Effects of the Specified Activity
on Marine Mammals and their Habitat section.
Description of Proposed Activity
Overview
Transco is proposing to expand its existing interstate natural gas
transmission system in Pennsylvania and New Jersey and its existing
offshore natural gas transmission system in New Jersey and New York
waters. The offshore pipeline facilities would include the installation
of the Raritan Bay Loop, which would be located primarily in Raritan
Bay, as well as parts of the Lower New York Bay and the Atlantic Ocean.
Construction of the Raritan Bay Loop pipeline would require
vibratory and impact installation and vibratory removal of 163
temporary piles, ranging in size from 10 to 60-inches (in) (0.3 to 1.5
meters (m)) in diameter, which may result in the incidental take of
marine mammals.
Dates and Duration
The proposed IHA would be valid for the statutory maximum of 1 year
from the date of effectiveness. It will become effective upon written
notification from the applicant to NMFS, but not beginning later than 1
year from the date of issuance or extending beyond 2 years from the
date of issuance. In-water construction is anticipated to occur between
the 2nd and 4th quarter of 2026, with pile installation and removal
activities planned for June through August 2026. Removal activities may
shift into fall 2026. However, project delays may occur due to a number
of factors including project funding, permitting requirements,
availability of equipment and/or materials, weather-related delays,
equipment maintenance and/or repair, and other contingencies etc.
All in-water construction and removal activities would be conducted
during daylight hours only. Pile installation and removal activities
are anticipated to take a total of 69 days.
Specific Geographic Region
Transco's proposed activity would occur in the waters of Raritan
Bay, the Lower New York Bay, and the Atlantic Ocean, off the coast of
New Jersey and New York, in a portion of the New York Bight sometimes
referred to as the New York Bight Apex (Brown et al., 2022). Leading to
the Port of New York and New Jersey, one of the busiest ports on the
East Coast and the third busiest port in the United States, this area
experiences significant commercial and recreational vessel activity.
Depths at the pile driving sites range from 4 to 13 m. The ensonified
areas associated with the planned activities extend to very shallow
areas to depths of 68 m.
BILLING CODE 3510-22-P
[[Page 38106]]
[GRAPHIC] [TIFF OMITTED] TN07AU25.000
[[Page 38107]]
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
Transco is proposing to expand its existing interstate natural gas
pipeline system in Pennsylvania and New Jersey and its existing
offshore natural gas pipeline system in New Jersey and New York waters
with the goal of providing an additional 400,000 dekatherms per day
transportation capacity to support its customers. To provide this
additional capacity, Transco proposes to expand portions of its system
from an existing compressor station in York County, Pennsylvania, to
the Rockaway Delivery Point in New York State waters, which represents
the interconnection point between Transco's existing LNYBL and the
existing offshore Rockaway Delivery Lateral. The proposed project would
consist of several components, including onshore pipeline facilities in
Pennsylvania and New Jersey and offshore pipeline facilities in New
Jersey and New York. Only the offshore pipeline components of the
project have the potential to result in the incidental take of marine
mammals, thus the onshore components of the project are not analyzed
further.
Transco's proposed offshore pipeline facilities include the Raritan
Bay Loop pipeline, which would be located primarily in Raritan Bay as
well as parts of Lower New York Bay and the Atlantic Ocean. The Raritan
Bay Loop would begin at the onshore connection with the Madison Loop in
Middlesex, New Jersey (see figure 2 in the IHA application). The
offshore portion of the Raritan Bay Loop would extend from the
Sayreville shoreline approximately 37.6 kilometers (km) across Raritan
Bay and Lower New York Bay to the Rockaway Transfer Point, which is the
interconnection point with the Rockaway Delivery Lateral in New York
state waters in the Atlantic Ocean, approximately 4.8 km seaward of
Rockaway, New York. Approximately 9.6 km of the offshore portion of the
Raritan Bay Loop route would cross New Jersey waters, while the
remaining 28 km would cross New York waters. The Raritan Bay Loop would
cross a continuous expanse of open marine and estuarine waters in New
Jersey and New York, which consists of three major contiguous
waterbodies, including Raritan Bay, Lower New York Bay, and the
Atlantic Ocean (See figures 1 and 2 in the application). This area is
included in the eastern-most portion of a larger coastal area known as
the New York Bight.
Construction of the Raritan Bay Loop pipeline would require the
installation of 163 piles, ranging in size from 10 to 60-in (0.3 to
1.5-m) in diameter, using vibratory and impact pile driving and
vibratory removal. Impact pile drivers are piston-type drivers that use
various means to lift a piston to a desired height and drop the piston
against the head of the pile in order to drive it into the substrate
(Caltrans, 2015). Diesel impact hammers would be used to install
approximately 34 steel piles (table 1). A vibratory device uses
spinning counterweights, causing the pile to vibrate at high speed. The
vibrating pile causes the soil underneath it to ``liquefy'' and allow
the pile to move easily into or out of the sediment. Vibratory devices
would be used to install and remove approximately 163 steel pipe piles
(table 1). Note that some piles would require both impact and vibratory
installation.
The total time to install a pile is dependent on the installation
method (vibratory or impact), diameter of the pile, substrate
composition, and depth the pile needs to penetrate through the
substrate. For pile installation of 34 to 60-in (0.9 to 1.5-m) piles
using a diesel impact hammer, the estimated time is 38 to 62 minutes
per pile. For pile installation of 10 to 60-in (0.3 to 1.5-m) piles
using a vibratory hammer, the estimated time is 15 minutes per pile.
For pile removal of 10 to 60-in (0.3 to 1.5-m) piles using a vibratory
hammer, the estimated time is 5 to 30 minutes per pile. The minimum
handling time (i.e., periods during which the pile is being positioned,
steadied, etc., and no in-water construction noise is anticipated) is
dependent on activity type and pile size. For vibratory hammer periods
for 10 to 48-in (0.3 to 1.2-m) piles, the handling time ranges from 15
to 45 minutes. For vibratory hammer periods for 60-in (1.5-m) piles,
the minimum handling time is 1 hour and 45 minutes. For impact hammer
periods, the minimum handling time is 30 minutes. The total duration of
pile installation (including both vibratory and impact pile driving) is
estimated at 43 days (of which impact pile driving would occur on up to
14 days and vibratory pile driving would occur on 43 days). The piles
would remain in the offshore environment only for the duration of each
related offshore construction activity. Once offshore construction is
complete, all piles would be removed using a vibratory hammer, which is
expected to occur over an estimated 26 days. Thus, the total duration
of pile installation and removal is 69 days (i.e., 43 days for pile
installation and 26 days for pile removal).
All piles would be installed along a string of locations within
Raritan Bay (see figure 2 in the IHA application). Transco would
complete construction of the various components of the offshore
pipeline in several stages with overlapping schedules. An overview of
these stages and their general sequence (i.e., temporary fixed
platform, pre-trenching, cable crossings and initial pipelay, Hydraulic
Directional Drilling (HDD) crossings, additional pipelay and backfill,
and subsea manifold tie-in, hydrostatic testing, and commissioning) are
described in Transco's application.
The various components of the proposed construction of the Raritan
Bay Loop pipeline, including pile type, size and quantity, installation
method (i.e., impact or vibratory), pile driving or removal duration,
are shown in table 1 and are described in greater detail in the IHA
application. At locations where more than one pile type is planned for
installation, Transco plans to install and remove two piles
simultaneously. The combination of piles that would create the largest
cumulative sound exposure level at a given location are presented in
table 2.
[[Page 38108]]
Table 1--Pile Driving Summary for Raritan Bay Loop Pipeline, Including Pile Types and Driving Durations
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Installation Removal
Pile size Number of ---------------------------------------------------------------------------------------------------
Mile Construction site Pile type (inches) piles Duration (minutes); Piles per Duration Removal Piles per Duration
Driving method strikes per pile day (days) time/ pile day (days)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
12.59.................... Morgan Shore Platform............ 36 18 Vibratory, Impact... 15; 1,920-\1\ 2,500. 4 4.5 30 8 3
Approach HDD. Platform Reaction... 36 4 Vibratory, Impact... 2 2 30
Support barge fender 36-48 4 Vibratory........... 15.................. 4 2 15 3 3
Water barge fender.. 36-48 4 Vibratory........... 15.................. 15
HDD sting goal post. 24 10 Vibratory........... 15.................. 4 3 5 4 3
13.84.................... Neptune Power Cable Sleeper vertical.... 10 8 Vibratory........... 15.................. 4 2 15 4 1.5
Crossing.
14.5 to 16.5............. Milepost (MP) 14.5 Morgan shore pull 24 22 Vibratory........... 15.................. 5 5 15 11 1.5
to MP 16.5. vertical guide.
28.0 to 29.36............ MP 28.0 to MP 29.36. Pipelay barge 34 12 Vibratory........... 15.................. 4 3 30 6 2
mooring.
29.4..................... Ambrose Channel HDD W750................ 36 3 Vibratory........... 15.................. 2 1.5 15 3 0.5
West. Reaction frame...... 36-60 8 Vibratory; Impact... 15; 3,382........... 2 4 30 8 0.5
Support barge fender 36-48 4 Vibratory........... 15.................. 4 1.5 15 8 1
Water barge fender.. 36-48 4 Vibratory........... 15.................. 15
HDD string goal 24 12 Vibratory........... 15.................. 6 1.5 5 6 2
posts.
30.48.................... Ambrose Channel HDD Vertical 24 22 Vibratory........... 15.................. 5 5 15 22 0.5
East Side. stabilization. 36 3 Vibratory........... 15.................. 3 0.5 15 3 0.5
W751 side piles.....
Support barge fender 36-48 4 Vibratory........... 15.................. 8 1 15 8 1
Water barge fender.. 36-48 4 Vibratory........... 15.................. 15
HDD drill sting goal 24 10 Vibratory........... 15.................. 5 1.5 5 5 2
posts.
Pipelay barge 60 1 Vibratory........... 15.................. 1 0.5 15 1 1
mooring pile.
34.5 to 35.04............ MP 34.5 to MP 35.04. Pipelay barge 34 4 Vibratory; Impact... 15; 1,920-2,500..... 2 3 15 2 2
mooring pile.
35.04.................... Neptune Power Cable Crossing pile....... 10 2 Vibratory........... 15.................. 2 1 15 2 1
Crossing MP 35.04.
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\1\ Maximum strikes per pile per day (i.e., 2,500) were used to calculate distances to Level A harassment isopleths.
[[Page 38109]]
Table 2--Simultaneous Pile Driving Scenarios That Result in the Largest Cumulative Sound Exposure Level at Each Location
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Installation/
Construction Pile size Total number Duration (minutes); removal Average number Number of days
Scenario site (inches) Activity of piles strikes per pile duration of piles per for concurrent
(days) day activities
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Installation
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1................ Morgan Shore 36 Impact............ 18 2,500 strikes....... 4.5 4 6.5
Approach HDD 36 Impact............ 4 2,500 strikes....... 2 2
(MP 12.59).
2................ Ambrose Channel 60 Impact............ 8 3,382 strikes....... 4 2 4
HDD West Side 48 Vibratory......... 4 15 minutes.......... 1.5 3
(MP 29.40).
3................ Ambrose Channel 48 Vibratory......... 4 15 minutes.......... 1 4 1
HDD East Side 48 Vibratory......... 4 15 minutes.......... 1 4
(MP 30.48).
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Removal
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4................ Morgan Shore 36 Vibratory......... 18 30 minutes.......... *3 6 3
Approach HDD 36 Vibratory......... 4 30 minutes.......... *3 1
(MP 12.59).
5................ Ambrose Channel 36 Vibratory......... 8 30 minutes.......... 0.5 8 1
HDD West Side 48 Vibratory......... 4 15 minutes.......... 1 4
(MP 29.4).
6................ Ambrose Channel 48 Vibratory......... 4 15 minutes.......... 1 4 1
HDD East Side 48 Vibratory......... 4 15 minutes.......... 1 4
(MP 30.48).
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* There are a total of 22 36-inch piles planned at Morgan Shore Approach HDD, 18 of which are platform piles (for temporary fixed platform); while the
other 4 are platform reaction piles; The overall extraction rate for 36-inch piles at Morgan Shore Approach HDD is 8 per day, but for purposes of this
concurrent pile extraction worst-case analysis, a more detailed extraction rate of 1.33 piles per day for the 4 platform reaction piles is used. As
such, production rates here do not match those presented in table 1.
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, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs; <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' 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 this activity and summarizes information
related to the population or stock, including regulatory status under
the MMPA and Endangered Species Act (ESA) and potential biological
removal (PBR), where known. 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 proposed
to be authorized here, PBR and annual serious injury and mortality (M/
SI) from anthropogenic sources are included here as gross indicators of
the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Atlantic SARs. All values presented in table 3 are the most
recent available at the time of publication (including from the draft
2024 SARs) and are available 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>.
Table 3--Species \1\ With Estimated Take From the Specified Activities
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ESA/ MMPA
status; Stock abundance (CV, Annual M/
Common name Scientific name Stock Strategic (Y/N) Nmin, most recent PBR SI \4\
\2\ abundance survey) \3\
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Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
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Family Balaenidae:
N Atlantic Right Whale \5\...... Eubalaena glacialis.... Western Atlantic....... E, D, Y 372 (0, 367, 2023).... 0.73 14.8
Family Balaenopteridae (rorquals):
Fin Whale....................... Balaenoptera physalus.. Western N Atlantic..... E, D, Y 6,802 (0.24, 5,573, 11 2.05
2021).
Humpback Whale.................. Megaptera novaeangliae. Gulf of Maine.......... -, -, N 1,396 (0, 1380, 2016). 22 12.15
Minke Whale..................... Balaenoptera Canadian Eastern -, -, N 21,968 (0.31, 17,002, 170 9.4
acutorostrata. Coastal. 2021).
[[Page 38110]]
Sei Whale....................... Balaenoptera borealis.. Nova Scotia............ E, D, Y 6,292 (1.02, 3,098, 6.2 0.6
2021).
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Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Long-Finned Pilot Whale \6\..... Globicephala melas..... Western N Atlantic..... -, -, N 39,215 (0.30, 30,627, 306 5.7
2021).
Short-Finned Pilot Whale \7\.... Globicephala Western N Atlantic..... -, -, Y 18,726 (0.33, 14,292, 143 218
macrorhynchus. 2021).
Atlantic Spotted Dolphin........ Stenella frontalis..... Western N Atlantic..... -, -, N 31,506 (0.28, 25,042, 250 0
2021).
Atlantic White-Sided Dolphin.... Lagenorhynchus acutus.. Western N Atlantic..... -, -, N 93,233 (0.71, 54,443, 544 28
2021).
Bottlenose Dolphin.............. Tursiops truncatus..... Northern Migratory -, -, Y 6,639 (0.41, 4,759, 48 12.2- 21.5
Coastal. 2016).
Western N Atlantic -, -, N 64,587 (0.24, 52,801, 507 28
Offshore \8\. 2021).
Common Dolphin.................. Delphinus delphis...... Western N Atlantic..... -, -, N 93,100 (0.56, 59,897, 1,452 414
2021).
Family Phocoenidae (porpoises):
Harbor Porpoise................. Phocoena phocoena...... Gulf of Maine/Bay of -, -, N 85,765 (0.53, 56,420, 649 145
Fundy. 2021).
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Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
Gray Seal \9\................... Halichoerus grypus..... Western N Atlantic..... -, -, N 27,911 (0.20, 23,624, 1,512 4,570
2021).
Harbor Seal..................... Phoca vitulina......... Western N Atlantic..... -, -, N 61,336 (0.08, 57,637, 1,729 339
2018).
Harp Seal....................... Pagophilus Western N Atlantic..... -, -, N 7.6M (UNK, 7.1M, 2019) 426,000 178,573
groenlandicus.
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\1\ 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>).
\2\ 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.
\3\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ 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, vessel 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.
\5\ The current SAR includes an estimated population (Nest 372) based on sighting history through November 2023. In October 2024, NMFS released a
technical report identifying that the North Atlantic right whale population size based on sighting history through 2023 was 372 whales, with a 95
percent credible interval ranging from 360 to 383 (Linden, 2024). Total annual average observed North Atlantic right whale mortality during the period
2018-2022 was 5.45 animals and annual average observed fishery mortality was 3.95 animals. Numbers presented in this table (14.8 total mortality and
10.8 fishery mortality) are 2018-2022 estimated annual means, accounting for undetected mortality and serious injury.
\6\ Key uncertainties exist in the population size estimate for this species, including uncertain separation between short-finned and long-finned pilot
whales, small negative bias due to lack of abundance estimate in the region between US and the Newfoundland/Labrador survey area, and uncertainty due
to unknown precision and accuracy of the availability bias correction factor that was applied.
\7\ A key uncertainty exists in the population size estimate for this species based upon the assumption that the logistic regression model accurately
represents the relative distribution of short-finned vs. long-finned pilot whales.
\8\ Estimates may include sightings of the coastal form.
\9\ NMFS' stock abundance estimate (and associated PBR value) applies to the U.S. population only. Total stock abundance (including animals in Canada)
is approximately 394,311. The annual M/SI value given is for the total stock.
As indicated above, all 15 number species (with 16 number managed
stocks) in table 3 temporally and spatially co-occur with the activity
to the degree that take is reasonably likely to occur. While sperm
whale could potentially occur in the project area, 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. Sperm whales typically occur in deeper waters than what are
included in the project area (Zoidis et al. 2021).
In addition to what is included in sections 3 and 4 of the IHA
application, and NMFS' website, further detail informing the regional
occurrence for select species of particularly or unique vulnerability
(i.e., information regarding ESA listed or MMPA depleted species,
information regarding current Unusual Mortality Events (UME) and known
important habitat areas such as Biologically Important Areas (BIAs))
(Van Parijs, 2015) is provided below. There is no ESA-designated
critical habitat for any species within the project area.
North Atlantic Right Whale
In December 2024, NMFS finalized the 2023 SARs, which updated the
North Atlantic right whale population estimate (N<INF>est</INF>) to 372
individuals, which is equal to the population estimate included in the
North Atlantic right whale Consortium's 2023 Report Card (Pettis et
al., 2024); between the final 2022 SAR and the final 2023 SAR, the
estimated annual mortality and serious injury (M/SI) value decreased
from 31.2 to 14.8. We note that beginning in the 2022 SARs, the M/SI
for North Atlantic right whale included the addition of estimated
undetected mortality and serious injury. There are no revisions to
N<INF>est</INF> or M/SI in the draft 2024 SAR.
Elevated North Atlantic right whale mortalities have occurred since
June 7, 2017, along the U.S. and Canadian coast, with the leading
category for the cause of death for this UME to be ``human interaction:
through entanglement and vessel strikes. As of July 30, 2025, there
have been 41 confirmed dead stranded whales, and 39 seriously injured
free-swimming whales for a total of 80 whales. The UME also considers
animals with sub-lethal injury or illness (called ``morbidity''; n= x)
bringing the total number of whales in the UME to 157. More information
about the North Atlantic right whale UME is available online at:
<a href="https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events">https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events</a>.
The eastern portion of the proposed project area spatially overlaps
with a BIA for migrating North Atlantic right whales, which is active
in March and
[[Page 38111]]
April (northward migration to feeding areas), and November and December
(southern migration to calving grounds) (LaBrecque et al., 2015; Van
Parijs et al., 2015). It is during this time (November through April)
that North Atlantic right whales are most likely to be found in the
vicinity of the proposed project area, and seasonal management areas
(SMAs) are in effect within a 37-kilometer (19-statute-mile) radius of
several major ports along the U.S. East Coast (73 FR 60173, October 10,
2008). A portion of the project area overlaps with an SMA associated
with the Port of New York and New Jersey. While North Atlantic right
whales are occasionally observed in nearshore waters near the project
site, their calls are most frequently detected in the shelf zone of the
New York Bight (between 25 m to 200 m water depth) (Zoidis et al.,
2021). Within the last 10 years, 12 sightings of 19 right whales have
been observed within the project area, off of Long Island, New Jersey,
and at the mouth of Upper Bay (between Brooklyn and Staten Island)
(Morrison and Taggart, 2021, accessed July 25, 2025). Dynamic
Management Areas (DMAs) that overlap with the project area have been
established on 18 occasions (including extensions) between January 2023
and June 2025. All DMAs occurred in the months of November through
March. DMAs are a voluntary program that NMFS uses to notify vessel
operators to slow down to avoid right whales. NMFS establishes DMAs
based on visual sightings of three or more right whales within a
distinct area. For a period of 15 days after whales are detected,
mariners are encouraged to avoid these areas or reduce speeds to 10
knots or less while transiting through these areas.
Recent research indicates our understanding of North Atlantic right
whale movement patterns remains incomplete (Davis et al., 2017). A
review of passive acoustic monitoring data from 2004 to 2014 throughout
the western North Atlantic demonstrated nearly continuous year-round
right whale presence across their entire habitat range (for at least
some individuals), including in locations previously thought of as
migratory corridors, suggesting that not all of the population
undergoes a consistent annual migration (Davis et al., 2017). However,
most of the north Atlantic right whales observed in the New York Bight
outside of the migration period are detected in deeper waters of the
continental shelf, much further offshore (Morrison and Taggart, 2021,
accessed July 25, 2025). Of the 11 sightings of North Atlantic right
whale observed in the project area (referenced above), just four
sightings of four individuals were reported within project waters
outside the migration period, in June and October 2020, and August 2021
(Morrison and Taggart, 2021, accessed July 25, 2025).
North Atlantic right whale foraging behavior has not been
documented near the coast of Long Island. The closest foraging sighting
to the project area was reported by the New England Aquarium in 2024,
in which over 82 unique individuals were observed during a series of
flights between the end of July into August 2024 about 40-70 miles
south and offshore of Long Island, between Hudson and Block Canyons
(New England Aquarium, 2024). Zoidis et al., 2021 also observed a right
whale skim feeding at the shelf break, further offshore than is
typical, in May 2019. Therefore, any right whales in the vicinity of
the project area are expected to be transient, either migrating through
the area from late fall until late April or spending short amounts of
time within the waters southeast of Long Island.
During Transco's LNYBL Maintenance Project, which was located in
Raritan Bay and Lower New York Bay, Protected Species Observers (PSOs)
monitored for marine mammals on 59 days between mid-July and late
October 2024, and reported no sightings of North Atlantic right whales.
Two sightings of five unidentified whales were reported, but PSOs
deduced they were not right whales based on the shapes of the dorsal
fins.
The project area does not overlap with designated critical habitat
for North Atlantic right whales.
Fin Whale
In the New York Bight, fin whales are most common in deeper waters
of the continental shelf (Estabrook et al., 2025, Lomack-Macnair et
al., 2022), particularly in the summer (Zoidis et al., 2021), though
they have been observed in nearshore waters off of long island in all
seasons (Sadove and Cardinale, 1993; Zoidis et al., 2021). During
monthly 36-line transect aerial surveys, fin whales were observed
closer to the project area primarily in the spring (Zoidis et al.,
2021).
During Transco's LNYBL Maintenance Project, PSOs reported no
sightings of fin whales during project monitoring described above.
However, two sighting of five unidentified whales were reported.
The project area does not overlap with any BIAs or other known
important areas for fin whales.
Humpback Whale
Humpback whales are one of the most frequently detected baleen
whale species throughout the New York Bight (Zoidis et al., 2021;
Estabrook et al., 2025). While it is unclear how long individual
humpback whales remain in the New York Bight, detections occur year-
round (Brown et al., 2022; Estabrook et al., 2025; Zoidis et al.,
2021). There is increasing evidence to suggest that the New York Bight
provides a supplemental foraging area for this species (Lomac-MacNair
et al., 2022; Estabrook et al., 2025), including in the project area
(Smith et al., 2022). The majority of sightings from whale watch trips
or public observations in the New York Bight Apex were reported between
July and September (Brown et al., 2022), though it is important to
recognize reduced observer effort in the winter months (i.e., there
were no whale watch trips during this time, only public reports).
Estabrook et al. (2025) noted that humpback whale calls were more
frequently detected near New York Harbor between November and March,
and at sites near the shelf edge between July and September.
During Transco's LNYBL Maintenance Project, PSOs reported eight
sightings of 10 humpback whales during project monitoring described
above. Additionally, two sightings of five unidentified whales were
reported.
Since January 2016, elevated humpback whale mortalities along the
Atlantic coast from Maine to Florida led to the declaration of a UME.
As of July 30, 2025, 257 humpback whales have stranded as part of the
UME. Partial or full necropsy examinations have been conducted on
approximately 90 of the known cases. Of the whales examined, about 40
percent had evidence of human interaction, either vessel strike or
entanglement. While a portion of the whales shown evidence of pre-
mortem vessel strike, this finding is not consistent across all whales
examined and more research is needed. Nearly a third of documented
strandings have occurred off New York and New Jersey. More information
is available at: <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events">https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events</a>.
The project area does not overlap with any BIAs for humpback
whales.
Minke Whale
North Atlantic minke whales migrate seasonally between high
latitude summer feeding grounds and low latitude winter breeding
grounds. While they have been sighted in all months of the year in the
New York Bight (Sadove
[[Page 38112]]
and Cardinale, 1993), the occurrence of minke whale in the mid-Atlantic
increases during the spring and summer (Risch et al., 2024, Lomac-
MacNair et al., 2022); acoustic array data analyzed by Rich et al.,
2014 detected minke whales off of NY in deep offshore waters, primarily
in March through May and reported few detections in autumn and winter
(note that summer data were not available at this NY site for this
study). Lomac-Macnair et al., 2022 observed minke whales may be using
the New York Bight region as supplementary feeding habitat in the
spring and summer.
Since January 2017, elevated minke whale mortalities have occurred
along the Atlantic coast from Main through Georgia. As of July 30,
2025, a total of 201 minke whales have stranded as part of the UME.
Partial or full necropsy examinations have been conducted on
approximately 60 percent of the known cases. Preliminary findings in
several of the whales have shown evidence of human interactions or
infectious diseases. These findings are not consistent across all of
the whales examined, so more research is needed. Nearly a quarter of
documented strandings have occurred off New York and New Jersey. More
information is available at: <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events">https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events</a>.
During Transco's LNYBL Maintenance Project, PSOs reported no
sightings of minke whales during project monitoring described above.
However, two sighting of five unidentified whales were reported.
The project area does not overlap with any BIAs or other known
important areas for minke whales.
Sei Whale
Sei whales have been detected acoustically along the Atlantic
Continental Shelf and Slope from south of Cape Hatteras, North Carolina
to the Davis Strait, and acoustic occurrence has been increasing in the
mid-Atlantic region since 2010 (Davis et al., 2020). Although their
migratory movements are not well understood, sei whales are believed to
migrate between feeding grounds in temperate and subpolar regions to
wintering grounds in lower latitudes (Kenney and Vigness-Raposa, 2010;
Hayes et al., 2020). Sei whales generally occur offshore and in deeper
waters (deeper waters of the continental shelf edge of the eastern
United States and northeastward to south of Newfoundland (Mitchell,
1975; Hain et al., 1985; Hayes et al., 2022); however, individuals may
also move into shallower, more inshore waters (Payne et al., 1990;
Halpin et al., 2009; Hayes et al., 2022).
During Transco's LNYBL Maintenance Project, PSOs reported no
sightings of sei whales during project monitoring described above.
However, two sighting of five unidentified whales were reported.
The project area does not overlap with any BIAs or other known
important areas for sei whales.
Phocid Seals
Harbor and gray seals have experienced two UMEs since 2018,
although one was closed in 2022 (pinniped UME in Maine) and closure of
the second, described here, is pending. Beginning in July 2018,
elevated numbers of harbor seal and gray seal mortalities occurred
across Maine, New Hampshire, and Massachusetts. Additionally, stranded
seals have shown clinical signs as far south as Virginia, although not
in elevated numbers, therefore the UME investigations encompassed all
seal strandings from Maine to Virginia. A total of 3,152 reported
strandings (of all species) occurred from July 1, 2018, through March
13, 2020. Full or partial necropsy examinations were conducted on some
of the seals and samples were collected for testing. Based on tests
conducted thus far, the main pathogen found in seals is phocine
distemper virus. NMFS is performing additional testing to identify any
other factors that may be involved in this UME, which is pending
closure. Information on this UME is available online at: <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events">https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events</a>.
Harbor seal, gray seal, and harp seal are most likely to occur
withint he project area during the winter and early spring (September
to May), with harbor seals primarily present between October to March.
Sandy Hook Beach is the closest known haulout to the project area. It
is approximately 2.9 km (1.8 mi) southwest of the project site, and is
used by both harbor seals and gray seals (Reynolds, 2024). The average
maximum daily count of pinnipeds reported by volunteers during winter
surveys between 2005 and 2024 is 68 (Reynolds, 2024). The Coastal
Research and Education Society of Long Island also implements
volunteer-based monitoring of pinnipeds at Cupsogue Beach,
approximately 72 km (45 mi) northeast of the Project Area. Additional
gray seal haulout sites are likely Little Gull Island and Great Gull
Island in Long Island Sound.
Pinnipeds were not detected during Transco's NYBL maintenance
project monitoring, described above.
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.). Generalized hearing ranges were
chosen based on the ~65 decibel (dB) threshold from composite
audiograms, previous analyses in NMFS (2018), and/or data from Southall
et al. (2007) and Southall et al. (2019). We note that the names of two
hearing groups and the generalized hearing ranges of all marine mammal
hearing groups have been recently updated (NMFS 2024) as reflected
below in table 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36 kHz.
whales).
High-frequency (HF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
Very High-frequency (VHF) cetaceans 200 Hz to 165 kHz.
(true porpoises, Kogia, river
dolphins, Cephalorhynchid,
Lagenorhynchus cruciger & L.
australis).
[[Page 38113]]
Phocid pinnipeds (PW) (underwater) 40 Hz to 90 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 68 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges may not be as broad. Generalized hearing range
chosen based on ~65 dB threshold from composite audiogram, previous
analysis in NMFS 2018, and/or data from Southall et al. 2007; Southall
et al. 2019. Additionally, animals are able to detect very loud sounds
above and below that ``generalized'' hearing range.
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) 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 in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals 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 of Marine Mammals 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 effects on
annual rates of recruitment or survival.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far (American National Standards Institute
(ANSI), 1995). The sound level of an area is defined by the total
acoustical energy being generated by known and unknown sources. These
sources may include physical (e.g., waves, wind, precipitation,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and anthropogenic sound
(e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current weather conditions and levels of biological and
shipping activity) but also on the ability of sound to propagate
through the environment. In turn, sound propagation is dependent on the
spatially and temporally varying properties of the water column and sea
floor, and is frequency-dependent. As a result of the dependence on a
large number of varying factors, ambient sound levels can be expected
to vary widely over both coarse and fine spatial and temporal scales.
Sound levels at a given frequency and location can vary by 10-20 dB
from day to day (Richardson et al., 1995). The result is that,
depending on the source type and its intensity, sound from the
specified activity may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
In-water construction activities associated with the project would
include impact and vibratory pile driving, and vibratory pile removal.
The sounds produced by these activities fall into one of two general
sound types: impulsive and non-impulsive. Impulsive sounds (e.g.,
explosions, gunshots, sonic booms, impact pile driving) are typically
transient, brief (less than 1 second), broadband, and consist of high
peak sound pressure with rapid rise time and rapid decay (ANSI, 1986;
National Institute of Occupational Safety and Health (NIOSH), 1998;
NMFS, 2018). Non-impulsive sounds (e.g., aircraft, machinery operations
such as drilling or dredging, vibratory pile driving, and active sonar
systems) can be broadband, narrowband or tonal, brief or prolonged
(continuous or intermittent), and typically do not have the high peak
sound pressure with rapid rise/decay time that impulsive sounds do
(ANSI, 1995; NIOSH, 1998; NMFS, 2018). The distinction between these
two sound types is important because they have differing potential to
cause physical effects, particularly with regard to hearing (e.g.,
Ward, 1997, in Southall et al., 2007).
Two types of hammers would be used on this project: impact and
vibratory. Impact hammers operate by repeatedly dropping a heavy piston
onto a pile to drive the pile into the substrate. Sound generated by
impact hammers is characterized by rapid rise times and high peak
levels, a potentially injurious combination (Hastings and Popper,
2005). Vibratory hammers install piles by vibrating them and allowing
the weight of the hammer to push them into the sediment. Vibratory
hammers produce significantly less sound than impact hammers. Peak
sound pressure levels (SPLs) may be 180 dB or greater, but are
generally 10 to 20 dB lower than SPLs generated during impact pile
driving of the same-sized pile (Oestman et al., 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).
The likely or possible impacts of Transco's proposed activity on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of equipment and personnel; however, any impacts to marine
mammals are expected to be primarily acoustic in nature. Acoustic
stressors include effects of heavy equipment operation during pile
installation and removal.
Acoustic Effects
The introduction of anthropogenic noise into the aquatic
environment from pile driving is the means by which marine mammals may
be harassed from Transco's specified activity. In general, animals
exposed to natural or anthropogenic sound may experience behavioral,
physiological, and/or physical effects, ranging in magnitude from none
to severe (Southall et al., 2007, 2019). In general, exposure to pile
driving noise has the potential to result in behavioral reactions
(e.g., avoidance, temporary cessation of foraging and vocalizing,
changes in dive behavior) and, in limited cases, an auditory threshold
shift (TS). Exposure to anthropogenic noise can also lead to
[[Page 38114]]
non-observable physiological responses such an increase in stress
hormones. Additional noise in a marine mammal's habitat can mask
acoustic cues used by marine mammals to carry out daily functions such
as communication and predator and prey detection. The effects of pile
driving on marine mammals are dependent on several factors, including,
but not limited to, sound type (e.g., impulsive vs. non-impulsive), the
species, age and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the sampling site and the
animal, received levels, behavior at time of exposure, and previous
history with exposure (Wartzok et al., 2004; Southall et al., 2007).
Here we discuss physical auditory effects (TSs) followed by behavioral
effects and potential impacts on habitat.
NMFS defines a noise-induced 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, 2024). The amount of TS is customarily expressed in
dB. A TS can be permanent or temporary. As described in NMFS (2018,
2024), 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).
Auditory injury and permanent threshold shift (PTS)--NMFS defines
auditory injury (AUD INJ) as ``damage to the inner ear that can result
in destruction of tissue . . . which may or may not result in PTS''
(NMFS, 2024). 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, 2024). Available data from humans and other terrestrial
mammals indicate that a 40-dB TS approximates PTS onset (Ward et al.,
1958, 1959; Ward 1960; Kryter et al., 1966; Miller, 1974; Ahroon et
al., 1996; Henderson et al., 2008). PTS levels for marine mammals are
estimates, as with the exception of a single study unintentionally
inducing PTS in a harbor seal (Reichmuth 2019), there are no empirical
data measuring PTS in marine mammals largely due to the fact that, for
various ethical reasons, experiments involving anthropogenic noise
exposure at levels inducing PTS are not typically pursued or authorized
(NMFS, 2018).
Temporary threshold shift (TTS)--A temporary, reversible increase
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS, 2018). Based on data from cetacean TTS measurements
(Southall et al., 2007, 2019), a TTS of 6 dB is considered the minimum
TS clearly larger than any day-to-day or session-to-session variation
in a subject's normal hearing ability (Schlundt et al., 2000; Finneran
et al., 2000, 2002). As described in Finneran (2015), marine mammal
studies have shown the amount of TTS increases with cumulative sound
exposure level (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 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).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound. While experiencing TTS, the hearing threshold rises,
and a sound must be at a higher level in order to be heard. In
terrestrial and marine mammals, TTS can last from minutes or hours to
days (in cases of strong TTS). In many cases, hearing sensitivity
recovers rapidly after exposure to the sound ends. For cetaceans,
published data on the onset of TTS are limited to captive bottlenose
dolphin, beluga whale, harbor porpoise, and Yangtze finless porpoise
(Neophocoena asiaeorientalis) (Southall et al., 2019). For pinnipeds in
water, measurements of TTS are limited to harbor seals, elephant seals
(Mirounga angustirostris), bearded seals (Erignathus barbatus) and
California sea lions (Zalophus californianus) (Kastak et al., 1999,
2007; Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b; Reichmuth et
al., 2019; Sills et al., 2020). TTS was not observed in spotted (Phoca
largha) and ringed (Pusa hispida) seals exposed to single airgun
impulse sounds at levels matching previous predictions of TTS onset
(Reichmuth et al., 2016). These studies examine hearing thresholds
measured in marine mammals before and after exposure to intense or
long-duration sound exposures. 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
for a species or hearing group, 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, 2019c). Note that in general, harbor
seals and harbor porpoises have a lower TTS onset than other measured
pinniped or cetacean species (Finneran, 2015). 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
(Mooney et al., 2009; Finneran et al., 2010; Kastelein et al., 2014,
2015). This means that TTS predictions based on the total, cumulative
SEL will overestimate the amount of TTS from
[[Page 38115]]
intermittent exposures, such as sonars and impulsive sources.
Nachtigall et al., (2018) describe 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). Additionally, the existing marine
mammal TTS data come from a limited number of individuals within these
species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above that inducing mild TTS (e.g., a 40-dB threshold
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007,
2019). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulsive sounds (such as
impact pile driving pulses as received close to the source) are at
least 6 dB higher than the TTS threshold on a peak-pressure basis and
PTS cumulative sound exposure level thresholds are 15 to 20 dB higher
than TTS cumulative sound exposure level thresholds (Southall et al.,
2007, 2019). Given the higher level of sound or longer exposure
duration necessary to cause PTS as compared with TTS, it is
considerably less likely that PTS could occur.
Activities for this project include impact and vibratory pile
driving and removal. For the proposed project, these activities could
occur at the same time at three out of eight locations, but 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 TS declines.
Behavioral Harassment--Exposure to noise from pile driving and
removal also has the potential to behaviorally disturb marine mammals.
Generally speaking, NMFS considers a behavioral disturbance that rises
to the level of harassment under the MMPA a non-minor response--in
other words, not every response qualifies as behavioral disturbance,
and for responses that do, those of a higher level, or accrued across a
longer duration, have the potential to affect foraging, reproduction,
or survival. Behavioral disturbance may include a variety of effects,
including subtle changes in behavior (e.g., minor or brief avoidance of
an area or changes in vocalizations), more conspicuous changes in
similar behavioral activities, and more sustained and/or potentially
severe reactions, such as displacement from or abandonment of high-
quality habitat. Behavioral responses may include changing durations of
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral
activities (such as socializing or feeding); eliciting a visible
startle response or aggressive behavior (such as tail/fin slapping or
jaw clapping); avoidance of areas where sound sources are located.
Pinnipeds may increase their haul out time, possibly to avoid in-water
disturbance (Thorson and Reyff, 2006). Behavioral responses to sound
are highly variable and context-specific and any reactions depend on
numerous intrinsic and extrinsic factors (e.g., species, state of
maturity, experience, current activity, reproductive state, auditory
sensitivity, time of day), as well as the interplay between factors
(e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al.,
2007, 2019; Weilgart, 2007; Archer et al., 2010). Behavioral reactions
can vary not only among individuals but also within an individual,
depending on previous experience with a sound source, context, and
numerous other factors (Ellison et al., 2012), and can vary depending
on characteristics associated with the sound source (e.g., whether it
is moving or stationary, number of sources, distance from the source).
In general, pinnipeds seem more tolerant of, or at least habituate more
quickly to, potentially disturbing underwater sound than do cetaceans,
and generally seem to be less responsive to exposure to industrial
sound than most cetaceans. Please see Appendices B and C of Southall et
al. (2007) and Gomez et al. (2016) for reviews of studies involving
marine mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2004). 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 above, 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; Wartzok et al., 2004; National Research Council (NRC), 2005).
Controlled experiments with captive marine mammals have showed
pronounced behavioral reactions, including avoidance of loud sound
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed
responses of wild marine mammals to loud pulsed sound sources (e.g.,
seismic airguns) have been varied but often consist of avoidance
behavior or other behavioral changes (Richardson et al., 1995; Morton
and Symonds, 2002; Nowacek et al., 2007).
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
[[Page 38116]]
Changes in dive behavior can vary widely and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior
may reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007). For example, harbor porpoise respiration rate increased in
response to pile driving sounds at and above a received broadband SPL
of 136 dB (zero-peak SPL: 151 dB re 1 micropascal ([mu]Pa); SEL of a
single strike: 127 dB re 1 [mu]Pa\2\-s) (Kastelein et al., 2013).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004),
respectively, while North Atlantic right whales (Eubalaena glacialis)
have been observed to shift the frequency content of their calls upward
while reducing the rate of calling in areas of increased anthropogenic
noise (Parks et al., 2007). In some cases, animals may cease sound
production during production of aversive signals (Bowles et al., 1994).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996; Bowers et al., 2018). 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 et al., 2001). However, it should
be noted that response to a perceived predator does not necessarily
invoke flight (Ford and Reeves, 2008), and whether individuals are
solitary or in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fishes and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a 5-day period did not cause any sleep
deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than 1 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 (i.e., meaningful) 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.
Across 59 monitoring days between mid-July and late October 2024,
Transco documented observations of marine mammals during construction
activities at a project site occurring in Raritan Bay and Lower New
York Bay (LNYBL
[[Page 38117]]
Maintenance Project) (see 89 FR 20170, March 21, 2024). PSOs reported 8
sightings of 10 humpback whales and 35 sightings of 370 bottlenose
dolphins in the project area. An additional 2 sightings of 5
unidentified cetaceans and 31 sightings of 262 unidentified dolphins
were also reported. During pile driving activities, a total of 6
humpback whales, 113 bottlenose dolphins, and 166 unidentified dolphins
were observed within the estimated Level B harassment zone. The
humpback whales were observed breaching, surfacing, blowing, and
feeding while the bottlenose dolphins were observed diving, porpoising,
surfacing, blowing and milling. The unidentified dolphins were
primarily surfacing but were also observed traveling, blowing, diving,
milling and breaching. No changes in behavior in response to the
activity were reported for any species.
Given the similarities in activities and habitat and the fact the
same species are involved, we expect similar behavioral responses of
marine mammals to Transco's specified activity. That is, disturbance,
if any, is likely to be temporary and localized.
Stress Response--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 this project based on observations of
marine mammals during previous, similar projects in the area.
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., 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. Raritan Bay, Lower New York Bay and the Atlantic Ocean where
the project area is located experiences significant commercial and
recreational vessel activity, and background sound levels are already
elevated.
Airborne Acoustic Effects--Airborne noise would primarily be an
issue for pinnipeds that are swimming or hauled out near the project
site within the range of noise levels elevated above the acoustic
criteria. We recognize that pinnipeds in the water could be exposed to
airborne sound that may result in behavioral harassment when looking
with their heads above water. Most likely, airborne sound would cause
behavioral responses similar to those discussed above in relation to
underwater sound. For instance, anthropogenic sound could cause hauled-
out pinnipeds to exhibit changes in their normal behavior, such as
reduction in vocalizations, or cause them to temporarily abandon the
area and move further from the source. However, these animals would
previously have been ``taken'' because of exposure to underwater sound
above the behavioral harassment thresholds, which are in all cases
larger than those associated with airborne sound. Thus, the behavioral
harassment of these animals is already accounted for in these estimates
of potential take. Therefore, we do not believe that authorization of
incidental take resulting from airborne sound for pinnipeds is
warranted, and airborne sound is not discussed further. Cetaceans are
not expected to be exposed to airborne sounds that would result in
harassment as defined under the MMPA.
Marine Mammal Habitat Effects
The proposed activities would not result in permanent impacts to
habitats used directly by marine mammals, but may have potential short-
term impacts to food sources such as forage fish. The proposed
activities could also affect acoustic habitat (see masking discussion
above), but meaningful impacts are
[[Page 38118]]
unlikely. There are no known foraging hotspots, or other ocean bottom
structures of significant biological importance to marine mammals
present in the project area. Therefore, the main impact issue
associated with the proposed activity would be temporarily elevated
sound levels and the associated direct effects on marine mammals, as
discussed previously. The most likely impact to marine mammal habitat
occurs from pile driving effects on likely marine mammal prey (e.g.,
fish). Impacts to the immediate substrate during installation and
removal of piles are anticipated, but these would be limited to minor,
temporary suspension of sediments, which could impact water quality and
visibility for a short amount of time, without any expected effects on
individual marine mammals. Impacts to substrate are therefore not
discussed further.
In-water Construction Effects on Potential Prey--Sound may affect
marine mammals through impacts on the abundance, behavior, or
distribution of prey species (e.g., crustaceans, cephalopods, fish,
zooplankton). Marine mammal prey varies by species, season, and
location and, for some, is not well documented. Here, we describe
studies regarding the effects of noise on known marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to noise depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Additional studies
have documented effects of pile driving on fish, although several are
based on studies in support of large, multiyear bridge construction
projects (e.g., Scholik and Yan, 2001, 2002; Popper and Hastings,
2009). Several studies have demonstrated that impulse sounds might
affect the distribution and behavior of some fishes, potentially
impacting foraging opportunities or increasing energetic costs (e.g.,
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al.,
1992; Santulli et al., 1999; Paxton et al., 2017). However, some
studies have shown no or slight reaction to impulse sounds (e.g., Pena
et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott
et al., 2012). More commonly, though, the impacts of noise on fish are
temporary.
SPLs of sufficient strength have been known to cause auditory
injury, non-auditory injury, and mortality in fish. However, in most
fish species, hair cells in the ear continuously regenerate and loss of
auditory function likely is restored when damaged cells are replaced
with new cells. Halvorsen et al. (2012a) showed that a TTS of 4-6 dB
was recoverable within 24 hours for one species. Impacts would be most
severe when the individual fish is close to the source and when the
duration of exposure is long. Injury caused by barotrauma can range
from slight to severe and can cause death, and is most likely for fish
with swim bladders. Barotrauma injuries have been documented during
controlled exposure to impact pile driving (Halvorsen et al., 2012b;
Casper et al., 2013).
The greatest potential impact to fishes during construction would
occur during impact pile driving which is estimated to occur on up to
14 days across the proposed project, with 7 days of impact pile driving
estimated at Morgan Shore Approach HDD (MP 12.59) (with a maximum of
15,000 strikes per day), 4 days of impact pile driving planned at
Ambrose Channel HDD West Side (with a maximum of 6,764 strikes per
day), and 3 days of impact pile driving planned at MP 34.5 to MP 35.04
(with a maximum of 5,000 strikes per day). There would in-water
construction activities would only occur during daylight hours,
allowing fish to forage and transit the project area in the evening.
Vibratory pile driving and removal would possibly elicit behavioral
reactions from fishes such as temporary avoidance of the area but is
unlikely to cause injuries to fishes or have persistent effects on
local fish populations.
The most likely impact to fishes from pile driving and removal
activities in the project area would be temporary behavioral avoidance
of the area. The duration of fish avoidance of the area after pile
driving stops is unknown but a rapid return to normal recruitment,
distribution, and behavior is anticipated. In general, impacts to
marine mammal prey species are expected to be minor and temporary.
Further, it is anticipated that preparation activities for pile driving
and removal (i.e., positioning of the hammer) and upon initial startup
of devices would cause fish to move away from the affected area where
injuries may occur. Therefore, relatively small portions of the
proposed project area would be affected for short periods of time, and
the potential for effects to fish would be temporary and limited to the
duration of sound-generating activities.
In summary, given the short daily duration of sound associated with
individual pile driving and removal, and the relatively small areas
being affected, pile driving and removal activities associated with the
proposed action 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 activity are
not likely to have more than short-term adverse effects on any prey
habitat or populations of prey species. Further, any impacts to marine
mammal habitat are not expected to result in significant or long-term
consequences for individual marine mammals, or to contribute to adverse
impacts on their populations.
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
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
[[Page 38119]]
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 source/s (i.e., impact and vibratory pile driving and
removal) has the potential to result in disruption of behavioral
patterns for individual marine mammals. There is also some potential
for auditory injury (AUD INJ) (Level A harassment) to result for all
hearing groups. However, 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 criteria above which NMFS believes there is
some reasonable potential for marine mammals to be behaviorally
harassed or incur some degree of AUD INJ; (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 Criteria
NMFS recommends the use of acoustic criteria 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 AUD INJ of some degree (equated to
Level A harassment). We note that the criteria for AUD INJ, as well as
the names of two hearing groups, have been recently updated (NMFS 2024)
as reflected below in the Level A harassment section.
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.
Transco's proposed activity includes the use of continuous
(vibratory pile driving and removal) and impulsive (impact pile
driving) sources, and therefore the RMS SPL thresholds of 120 and 160
dB re 1 [mu]Pa are applicable.
Level A Harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive).
Transco's proposed activity includes the use of impulsive (impact pile
driving) and non-impulsive (vibratory pile driving and removal)
sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in the table below. The references, analysis,
and methodology used in the development of the criteria are described
in NMFS' 2024 Updated Technical Guidance, which may be accessed at:
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.
Table 5--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ onset acoustic thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 222 dB; Cell 2: LE,LF,24h: 197 dB.
LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,HF,24h: 201 dB.
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,VHF,24h: 181 dB.
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 223 dB; Cell 8: LE,PW,24h: 195 dB.
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 230 dB; Cell 10: LE,OW,24h: 199 dB.
LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
[[Page 38120]]
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [micro]Pa\2\s. In this table, criteria 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 underwater (i.e., 7 Hertz (Hz) to 165 Kilohertz (kHz)). The subscript
associated with cumulative sound exposure level criteria indicates the designated marine mammal auditory
weighting function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation
period is 24 hours. The weighted cumulative sound exposure level criteria 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 criteria 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., vibratory pile driving and
removal, and impact pile driving).
The project includes vibratory pile installation and removal, and
impact pile driving. Since there would be many piles at each of the
eight construction sites within close proximity to one another, Transco
found, and NMFS agreed, that it was not practical to estimate
harassment zones for each individual pile at specific locations and
results would have been nearly identical for all similarly sized piles
at each construction location. In order to simplify calculations, a
representative pile site was selected for the eight separate pile
locations (figure 1). For strings where only a single pile type would
be installed or removed (i.e., Neptune Power Cable Crossing MP 13.84
and MP 35.04, MP 14.5 to MP 16.5, MP 28 to MP 29.36, and MP 34.5 to MP
35.04), Transco selected a representative location in the middle of the
string. For the Morgan Shore Approach HDD string site, Transco selected
the location closest to the platform installation as the representative
pile location because it represents the area with the largest pile
sizes. At the HDD Ambrose West Side and HDD Ambrose East Side
locations, Transco's representative pile locations were selected based
on the entry and exit pits. The HDD Ambrose East Side is the entry pit
and the HDD Ambrose West Side is the exit pit. This would also
represent the outer limit of the HDD Ambrose string, and is therefore
the most conservative modeling option.
In its application, Transco indicated that it identified source
levels for installation and removal of each pile type and size using
the compendium compiled by Caltrans 2015, but also referenced Caltrans,
2020 and Illingworth & Rodkin, 2017. Transco did not specify which
sound levels were based on which reference. NMFS revised source levels
for these activities based on reviews of measurements of the same or
similar types and dimensions of piles available in the literature
(table 6). NMFS and Transco assumed that the representative sound
source levels were based on the largest pile expected to be driven/
removed at each potential in-water construction site. For example,
where Transco may use a range of pile sizes (i.e., 36 to 48-in piles),
the largest potential pile size (48-in) was used in modeling. Source
levels for vibratory installation and removal are assumed to be the
same.
Additionally, while not included in its application, Transco
indicated that two hammers, including a combination of vibratory and
impact hammers, may operate simultaneously at three out of eight
locations. As such, source levels for the combination of piles that
would create the largest cumulative sound exposure level at location
are also presented in table 6.
The methods for how the source levels for these concurrent
activities are derived are described here: When two noise sources have
overlapping sound fields, the sources are considered additive and
combined using the rules of dB addition. For addition of two
simultaneous sources, the difference between the two sound source
levels is calculated, and if that difference is between 0 and 1 dB, 3
dB are added to the higher sound source levels; if the difference is
between 2 and 3 dB, 2 dB are added to the highest sound source levels;
if the difference is between 4 and 9 dB, 1 dB is added to the highest
sound source levels; and with differences of 10 or more dB, there is no
addition. For two simultaneous sources of different type (i.e., impact
and vibratory driving), there is no sound source addition. In such
cases, the isopleth associated with the individual source which results
in the largest isopleths is conservatively used for both sources to
account for periods of overlapping activities.
Table 6--Estimates of Mean Underwater Sound Levels \1\ Generated During Vibratory and Impact Pile Driving and
Vibratory Removal of Temporary Steel Piles
----------------------------------------------------------------------------------------------------------------
Pile size
Method (inches) dB RMS dB Peak dB SEL References
----------------------------------------------------------------------------------------------------------------
Vibratory............................. 10 155 N/A N/A Caltrans 2015.
24 157 N/A N/A Caltrans 2020.
34 170 N/A N/A Caltrans 2015.
36 170 N/A N/A Caltrans 2015.
48 170 N/A N/A NMFS 2024.\2\
60 170 N/A N/A NMFS 2024.\2\
Impact................................ 34 193 210 183 Caltrans 2015, Caltrans
2020.
36 193 210 183 Caltrans 2015, Caltrans
2020.
60 193 210 185 Caltrans 2020.
Impact, Impact \3\.................... 36, 36 196 213 183 Caltrans 2015.
Impact, Vibratory..................... 60, 48 170 210 185 Caltrans 2020.
Vibratory, Vibratory \3\.............. 48, 48 173 N/A N/A NMFS 2024.\2\
36, 36 173 N/A N/A
36, 48 173 N/A N/A
----------------------------------------------------------------------------------------------------------------
Note: dB peak = peak sound level; rms = root mean square; SEL = sound exposure level.
\1\ All sound levels are referenced at 10 m.
\2\ Refers to a NMFS compendium of recommended source level proxies.
[[Page 38121]]
\3\ Source levels adjusted following rules of dB addition described above.
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 x Log10 (R<INF>1</INF>/R<INF>2</INF>),
where
TL = transmission loss in dB
B = transmission loss coefficient
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
Absent site-specific acoustical monitoring with differing measured
TL, a practical spreading value of 15 is used as the TL coefficient in
the above formula. Site-specific TL data for the New York Bight are not
available; therefore, the default coefficient of 15 is used to
determine the distances to the Level A harassment and Level B
harassment thresholds.
The ensonified area associated with Level A harassment is more
technically challenging to predict due to the need to account for a
duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the 2024 Updated 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 pile driving and removal, 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 AUD INJ. Inputs used in the optional User Spreadsheet
tool, and the resulting estimated isopleths, are reported in tables 7
and 8.
To calculate Level A harassment isopleths for two impact hammers
operating simultaneously, the NMFS User Spreadsheet calculator was used
with modified inputs to account for the total estimated number of
strikes for all piles. For simultaneous impact pile driving of two 36-
in steel piles (the most conservative scenario identified at Morgan
Shore Approach HDD MP 12.59), the total estimated number of strikes per
day was summed to estimate total sound exposure during simultaneous
installation, and the number of piles per day was reduced to one. The
source level for two simultaneous impact hammers was not adjusted
because for identical sources the accumulation of energy depends only
on the total number of strikes, whether or not they overlap fully in
time.
To calculate the Level A harassment isopleths for one impact and
one vibratory hammer operating simultaneously, sources were treated as
though they were non-overlapping. The isopleths associated with the
individual source which results in the largest Level A harassment
isopleths were conservatively used for both sources to account for
periods of overlapping activities.
To calculate Level A harassment isopleths for two simultaneous
vibratory hammers, the NMFS User Spreadsheet was used with modified
inputs to account for accumulation, weighting, and source overlap in
space and time. Using the rules of dB addition described above (i.e.,
if the difference between the two source levels is between 0 and 1 dB,
3 dB are added to the higher sound source level), the combined sound
source level for the simultaneous vibratory installation of two 48-in
steel piles, or two 36-in steel piles, or a 36-in and a 48-in steel
pile is 173 dB RMS in all cases.
Table 7--User Spreadsheet Inputs: Single Pile Driving Scenarios
--------------------------------------------------------------------------------------------------------------------------------------------------------
Weighting
factor Duration to
Location Pile size Spreadsheet tab used adjustment Piles per day drive a single Strikes
(kHz) pile (minutes)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 12.59)...... 24 A.1 Vibratory pile driving.. 2.5 4 15 N/A
36 4
48 4
36 E.1 Impact pile driving..... 2 4 N/A 2,500
Neptune Power Cable Crossing (MP 13.84)... 10 A.1 Vibratory pile driving.. 2.5 4 15 N/A
MP 14.5 to MP 16.5........................ 24 A.1 Vibratory pile driving.. 2.5 5 15 N/A
MP 28.0 to MP 29.36....................... 34 A.1 Vibratory pile driving.. 2.5 4 15 N/A
HDD Ambrose West Side (MP 29.4)........... 24 A.1 Vibratory pile driving.. 2.5 6 15 N/A
36 2
48 4
60 2
E.1 Impact pile driving..... 2 2 N/A 3,382
HDD Ambrose East Side (MP 30.48).......... 24 A.1 Vibratory pile driving.. 2.5 5 15 N/A
36 3
48 8
60 1
MP 34.5 to MP 35.04....................... 34 A.1 Vibratory pile driving.. 2.5 2 15 N/A
E.1 Impact pile driving..... 2 2 15 2,500
Neptune PC Crossing (MP 35.04)............ 10 A.1 Vibratory pile driving.. 2.5 2 15 N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------
Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 12.59)...... 24 A.1 Vibratory pile driving.. 2.5 5 4 N/A
36 30 8
48 15 3
[[Page 38122]]
Neptune PC Crossing (MP 13.84)............ 10 A.1 Vibratory pile driving.. 2.5 15 4 N/A
MP 14.5 to MP 16.5........................ 24 A.1 Vibratory pile driving.. 2.5 15 11 N/A
MP 28.0 to MP 29.36....................... 34 A.1 Vibratory pile driving.. 2.5 30 6 N/A
HDD Ambrose West Side (MP 29.4)........... 24 A.1 Vibratory pile driving.. 2.5 5 6 N/A
36 15 3
48 15 8
60 30 8
HDD Ambrose East Side (MP 30.48).......... 24 A.1 Vibratory pile driving.. 2.5 15 22 N/A
36 3
48 8
60 1
MP 34.5 to MP 35.04....................... 34 A.1 Vibratory pile driving.. 2.5 15 2 N/A
Neptune PC Crossing (35.04)............... 10 A.1 Vibratory pile driving.. 2.5 15 2 N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 8--User Spreadsheet Inputs: Simultaneous Pile Driving Scenarios
--------------------------------------------------------------------------------------------------------------------------------------------------------
Weighting
Pile sizes (inches) and factor Duration to
Location methods Spreadsheet tab used adjustment Piles per day drive a single Strikes
(kHz) pile (minutes)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 12.59). 36 impact, 36 impact.... E.1 Impact pile driving 2 1 N/A 15,000
HDD Ambrose West Side (MP 29.4)...... 60 impact, 48 vibratory. E.1 Impact pile driving 2 2 N/A 3,382
HDD Ambrose East Side (MP 30.48)..... 48 vibratory, 48 A.1 Vibratory pile 2.5 1 60 N/A
vibratory. driving.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 12.59). 36 vibratory, 36 A.1 Vibratory pile 2.5 1 40 N/A
vibratory. driving.
HDD Ambrose West Side (MP 29.4)...... 36 vibratory, 48 A.1 Vibratory pile 2.5 1 60 N/A
vibratory. driving.
HDD Ambrose East Side (MP 30.48)..... 48 vibratory, 48 A.1 Vibratory pile 2.5 1 60 N/A
vibratory. driving.
--------------------------------------------------------------------------------------------------------------------------------------------------------
NMFS has established Level B harassment thresholds of 160 dB
re1[mu]Pa (rms) for impulsive sounds (e.g., impact pile driving) and
120 dB re1[mu]Pa (rms) for non-impulsive sounds (e.g., vibratory
driving and removal). Based on the predicted source levels associated
with various pile sizes (table 6) the distances from the pile driving/
removal equipment to the Level B harassment thresholds were calculated,
using the distance to the 160 dB threshold for the impact hammer and
the distance to the 120 dB threshold for the vibratory device, at the
representative pile locations (table 9). It should be noted that while
sound levels associated with the Level B harassment threshold for
vibratory driving/removal were estimated to propagate as far as 34,146
m from pile installation and removal activities based on modeling, it
is likely that the noise produced from vibratory activities associated
with the project would be masked by background noise before reaching
this distance, as the Port of New York and New Jersey, which represents
the busiest port on the east coast of the United States and the third
busiest port in the United States, is located near the project area and
sounds from the port and from vessel traffic propagate throughout the
project area. However, take estimates conservatively assume propagation
of project-related noise to the full extent of the modeled isopleth
distance to the Level B harassment threshold. The modeled distances to
isopleths associated with Level B harassment thresholds for impact and
vibratory driving are shown in table 9.
Table 9--Projected Distances to Level A and Level B Harassment Isopleths (m) (and Associated Areas \1\ (km\2\) by Marine Mammal Hearing Group
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment zones (m) (areas km\2\) Level B
Location Pile size Hammer type ---------------------------------------------------------------------- harassment
(inches) LF HF VHF PW zone
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 24 Vibratory........ 5................... 1.9 4.1 6.4 2,929
12.59). 36 36.7................ 14.1 30.0 47.3 21,544
48 36.7................ 14.1 30.0 47.3 1,584
36 Impact........... 4,618.4............. 589.3 7,147.0 4,102.8 2,512
36 and 36 Impact and Impact 6,052 (34.20)....... 772 (1.72) 9,365 (59.13) 5,376 (29.19) 21,544
Neptune PC Crossing (MP 13.84). 10 Vibratory........ 3.7................. 1.4 3.0 4.7 2,154
MP 14.5 to MP 16.5............. 24 Vibratory........ 5.8................. 2.2 4.7 7.5 2,929
MP 28.0 to MP 29.36............ 34 Vibratory........ 36.7................ 14.1 30.0 47.3 21,544
[[Page 38123]]
HDD Ambrose West Side (MP 29.4) 24 Vibratory........ 6.5................. 2.5 5.3 8.4 2,929
36 23.1................ 8.9 18.9 29.8 21,544
48 36.7................ 14.1 30.0 47.3 21,544
60 23.1................ 8.9 18.9 29.8 21,544
Impact........... 4,837.6............. 617.2 7,486.1 4,297.5 2,154
60 and 48 Impact and 4,837.6 (72.22)..... 617.2 (1.20) 7,486.1 4,297.5 34,146 (1502)
Vibratory. (159.37) (57.63)
HDD Ambrose East Side (MP 24 Vibratory........ 5.8................. 2.2 4.7 7.5 2,929
30.48). 36 30.3................ 11.6 24.8 39.0 21,544
48 58.3................ 22.4 47.6 75.0 21,544
60 14.6................ 5.6 11.9 18.8 21,544
48 and 48 Vibratory and 58.3................ 22.4 47.6 75.0 34,146 (1502)
Vibratory.
MP 34.5 to MP 35.04............ 34 Vibratory........ 23.1................ 8.9 18.9 29.8 21,544
Impact........... 2,909.4 (62.49)..... 371.2 (0.43) 4,502.3 2,584.6 1,585
(62.49) (20.99)
Neptune PC Crossing (MP 35.04). 10 Vibratory........ 2.3................. 0.9 1.9 3.0 2,154
(14.58)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 24 Vibratory........ 2.4................. 0.9 2.0 3.1 2,929
12.59). 36 92.5................ 35.5 75.6 119.1 21,544
48 30.3................ 11.6 24.8 39.0 21,544
36 and 36 Vibratory and 44.4................ 17.1 36.3 57.2 34,146 (1539)
Vibratory.
Neptune PC Crossing (MP 13.84). 10 Vibratory........ 3.7................. 1.4 3.0 4.7 2,154
MP 14.5 to MP 16.5............. 24 Vibratory........ 9.8................. 3.8 8.0 12.6 2,929
MP 28.0 to MP 29.36............ 34 Vibratory........ 76.4................ 29.8 62.4 98.3 21,544
HDD Ambrose West Side (MP 29.4) 24 Vibratory........ 3.1................. 1.2 2.6 4.0 2,929
36 30.3................ 11.6 24.8 39.0 21,544
48 58.3................ 22.4 47.6 75.0 21,544
60 92.5................ 35.5 75.6 119.1 21,544
36 and 48 Vibratory and 58.3................ 22.4 47.6 75.0 34,146
Vibratory.
HDD Ambrose East Side (MP 24 Vibratory........ 15.6................ 6.0 12.7 20.0 2,929
30.48). 36 30.3................ 11.6 24.8 39.0 21,544
48 58.3................ 22.4 47.6 75.0 21.544
60 14.6................ 5.6 11.9 18.8 21.544
48 and 48 Vibratory and 58.3................ 22.4 47.6 75.0 34,146
Vibratory.
MP 34.5 to MP 35.04............ 34 Vibratory........ 23.1................ 8.9 18.9 29.8 21,544
Neptune PC Crossing (35.04).... 10 Vibratory........ 2.3................. 0.9 1.9 3.0 2,154
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Only areas relevant for take estimates (the largest Level B harassment zones at each location, and the largest Level A harassment zones associated
with impact pile driving at each location) are presented.
Level A harassment zones are typically smaller than Level B
harassment zones. However, during impact pile driving, the calculated
Level A harassment isopleth is greater than the calculated Level B
harassment isopleth for low frequency cetaceans, very high-frequency
cetaceans and phocids (however, because all activities are assumed as
potentially occurring on the same day, we functionally reference the
largest Level A and Level B harassment zones for purposes of estimating
take). Calculation of Level A harassment isopleths includes a duration
component, which in the case of impact pile driving, is estimated
through the total number of daily strikes and the associated pulse
duration. For a stationary sound source such as impact pile driving, we
assume here that an animal is exposed to all of the strikes expected
within a 24-hour period. Calculation of a Level B harassment zone does
not include a duration component.
Marine Mammal Occurrence
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations. Additionally, we describe how the
occurrence information is synthesized to produce a quantitative
estimate of the take that is reasonably likely to occur and proposed
for authorization.
To estimate take during impact and vibratory pile driving and
removal, Transco first generated an annual average density estimate for
each noise-producing scenario, for each species, using Duke University
Marine Geospatial Ecology Laboratory marine mammal habitat-based
density data (<a href="https://seamap.env.duke.edu/models/Duke/EC/">https://seamap.env.duke.edu/models/Duke/EC/</a>) (Roberts et
al., 2016; Roberts et al., 2023, Roberts et al., 2024). Instead of
generating average annual density estimates for each species for each
noise producing scenario, NMFS subsequently created a single project
area that encompassed the largest Level B harassment zones across each
of the eight project locations. This project area was used as the basis
for generating an annual average density estimate and an average
density estimate between June and November, which corresponds to the
planned project period, for each species. Specifically, in a Geographic
Information System, for each month and each species, the density
rasters were clipped to the polygon representing the above referenced
project area. To generate the annual average density estimate for each
species, the density estimates for each clipped density raster (January
through December) were summed and divided by 12 (table 10). To generate
the average density across June through November, the density values
for each clipped density raster (June through November) were summed
[[Page 38124]]
and divided by 6. In both cases, the mean density values for each
species were selected to use as a basis for take estimates.
Table 10--Marine Mammal Density Estimates Generated for the Transco Northeast Supply Enhancement Project Area
----------------------------------------------------------------------------------------------------------------
Mean densities (January- Mean densities (June-
Marine mammal species December) animals/100 November) animals/100
km\2\ km\2\
----------------------------------------------------------------------------------------------------------------
North Atlantic Right Whale.................................... 0.021304616299007 0.0030074206269121
Fin Whale..................................................... 0.034273800129881 0.019738282989868
Humpback Whale................................................ 0.057397781000022 0.032971508482719
Minke Whale................................................... 0.094349173218718 0.027476606940787
Sei Whale..................................................... 0.013016774291886 0.0056379703117625
Pilot Whale spp guild \2\..................................... 0.0010383579896433 0.0010383579896433
Atlantic Spotted Dolphin...................................... 0.012827813937997 0.025403273029717
Atlantic White-Sided Dolphin.................................. 0.1092249846683 0.068747673449369
Bottlenose Dolphin \1\........................................ 5.2491380360819 8.0931224515361
Common Dolphin................................................ 0.9122067405692 0.63518957481269
Harbor Porpoise............................................... 0.8396537609158 0.022988098221005
Seal guild \3\................................................ 8.6582116388505 8.0272698748496
----------------------------------------------------------------------------------------------------------------
\1\ The Duke University density data treats all bottlenose dolphins as a single group and as such are not subset
between the Migratory Coastal stocks and the Offshore stocks by the 20-meter isobath.
\2\ The Duke University density data for pilot whale spp. is not broken up for each species and only a single
density file is available. The density here represents the entire guild and will be the same for the annual
mean or the June to November analysis.
\3\ The Duke University data for pinnipeds is not broken up for each species that could occur and represents the
density for the guild.
In addition to consulting the output of marine mammal habitat-based
density models, NMFS also consulted the following data sets: (1)
Monitoring data associated with Transco's LNYBL Maintenance Project in
Sandy Hook Channel, New Jersey, in which PSO's monitored for marine
mammals on 59 days between mid-July and late October 2024 in Raritan
and Lower New York Bays; and, (2) group sizes derived from NOAA
Atlantic Marine Assessment Program for Protected Species data from
2010-2019 shipboard distance sampling surveys (Palka et al., 2021).
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. Generally, take
estimates are the product of density, ensonified area, and number of
days of pile driving work. Specifically, take estimates are calculated
by multiplying the expected densities of marine mammals in the activity
area(s) by the area of water likely to be ensonified above the NMFS
defined threshold levels in a single day (24-hr period) and the number
of construction days planned. A summary of this method is illustrated
in the following formula:
Estimated Take = D x ZOI x # of construction days
Where:
D = density estimate for each species (individuals/km\2\) within the
ZOI. (Note that since densities in Roberts et al. (2023, 2024) are
provided in individuals per 100 square km, they were converted to
individuals per square km for ease of use in generating take
estimates).
ZOI = maximum daily ensonified area to relevant thresholds (km\2\)
To estimate take, Transco initially proposed to multiply location-
specific annual average density estimates for each species by the ZOI
associated with each noise-producing activity, by the number of
construction days estimated for each noise-producing activity (based on
pile size and location). Activity-specific take estimates were then
summed to generate an overall take estimate for each species across the
project.
Because any activity could occur on any construction day, NMFS
instead multiplied the density estimate generated for the entire
project area by the largest ZOI associated with each of the eight
project locations by the total number of construction days planned at
each location. The resulting location-specific take estimates were
summed to generate an overall take estimate for each species across the
project. To be conservative, NMFS compared the results using the annual
average density estimate for each species and the average density
estimate for June through November and selected the largest result to
use as the basis for its proposed take authorization.
NMFS used the same equation to calculate take by Level A
harassment, with the ZOIs referring to the largest hearing group
specific Level A harassment zones at each location, during impact pile
driving activities only. Because Transco plans to shut down at
distances greater than the Level A harassment zones during vibratory
activities, only impact pile driving activities were included in
estimates of take by Level A harassment.
The ZOI's and total construction days used in density-based take
analyses are presented in the tables 11 and 12.
[[Page 38125]]
Table 11--The ZOI's and Total Construction Days Used in Density-Based
Estimates of Take by Level B Harassment
------------------------------------------------------------------------
Total
construction days
associated with
vibratory pile
ZOIs at each driving
representative pile (installation and
Location driving location removal) \1\ at
(km\2\) (and each
associated representative
isopleths (m)) pile driving
location (and
associated
isopleths (m))
------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 373 km\2\ (34,146 21
12.59). m).
Neptune Power Cable Crossing (MP 15 km\2\ (2,154 m). 4
13.84).
MP 14.5 to MP 16.5.............. 24 km\2\ (2,929 m). 7
MP 28.0 to MP 29.36............. 761 km\2\ (21,544 5
m).
HDD Ambrose West Side (MP 29.4). 1502 km\2\ (34,146 13
m).
HDD Ambrose East Side (MP 30.48) 1502 km\2\ (34,146 14
m).
MP 34.5 to MP 35.04............. 857 km\2\ (21,544 5
m).
Neptune Power Cable Crossing (MP 15 km\2\ (2,154 m). 2
35.04).
------------------------------------------------------------------------
\1\ Total construction days have been rounded up.
Table 12--The ZOI's and Total Construction Days Used in Density-Based Estimates of Take by Level A Harassment
----------------------------------------------------------------------------------------------------------------
ZOI representing the largest hearing group specific Level A Total
harassment zones (km\2\) at each location during impact pile construction
driving (and associated isopleths (m)) days
Location -------------------------------------------------------------------- associated
with impact
LF HF VHF PW pile driving
\1\
----------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD 34.2 km\2\ 1.72 km\2\ (722 59.13 km\2\ 29.19 km\2\ 7
(MP 12.59). (6,052 m). m). (9,365 m). (5,376 m).
HDD Ambrose West Side (MP 72.23 km\2\ 1.20 km\2\ (617 159.37 km\2\ 57.63 km\2\ 4
29.4). (4,838 m). m). (7,486 m). (4,298 m).
MP 34.5 to MP 35.04......... 26.59 km\2\ 0.43 km\2\ (371 62.49 km\2\ 20.99 km\2\ 3
(2,909 m). m). (4,502 m). (2,585 m).
----------------------------------------------------------------------------------------------------------------
\1\ Total construction days have been rounded up.
Monitoring data reported by PSO's during Transco's LNYBL
Maintenance project in Raritan Bay, Lower New York Bay, and the
Atlantic Ocean, in which PSOs monitored for marine mammals on 59 days
between July and October 2024, were also consulted to inform estimates
of take by Level A harassment.
A total of eight sightings of 10 humpback whales were observed
within 4,000 m of the pile driving source, translating to approximately
one sighting of humpback whales per week. The maximum group size
reported during this project was two humpback whales. As such, NMFS
proposes to authorize take by Level A harassment of one group of two
humpback whales each week that impact pile driving activities are
planned (two weeks). Therefore, NMFS proposes to authorize four takes
by Level A harassment of humpback whale (1 group x 2 humpback whales x
2 weeks of impact pile driving).
During Transco's LNYBL project, PSOs also reported an average of 6
bottlenose or unidentified dolphins each day occurring within 770 m of
the pile driving source, which represents the largest Level A
harassment zones associated with impact pile driving proposed for this
project. As such, NMFS proposed to authorize six takes by Level A
harassment for each construction day that impact pile driving is
planned (14 days). Therefore, NMFS proposes to authorize 84 takes by
Level A harassment of bottlenose dolphins (6 takes of bottlenose
dolphins x 14 construction days = 84 takes by Level A harassment of
bottlenose dolphin).
Additional data regarding average group sizes from survey effort in
the region was considered to ensure adequate take estimates are
evaluated. Take estimates for several species were adjusted based on
average group sizes derived from NOAA Atlantic Marine Assessment
Program for Protected Species data from 2010-2019 shipboard distance
sampling surveys (Palka et al., 2021). This is particularly true for
uncommon or rare species with very low densities in the models. The
calculated take estimates were adjusted for species as follows:
<bullet> Pilot whales (long-finned and short-finned): Only one take
by Level B harassment was estimated. Takes proposed for authorization
were increased to the average number of pilot whales in a group
reported in Palka et al., 2021 (n = 14) and applied to both stocks; and
<bullet> Atlantic spotted dolphin: Only 14 takes by Level B
harassment were estimated. Takes proposed for authorization were
increased to the average number of dolphins in a group reported in
Palka et al., 2021 (n = 25).
For bottlenose dolphins, the density data presented by Roberts et
al., (2023, 2024) does not differentiate between stocks. Thus, the take
estimate for bottlenose dolphins calculated by the method described
above resulted in an estimate of the total number of bottlenose
dolphins expected to be taken, from all stocks. However, as described
above, both the Western North Atlantic Northern Migratory Coastal stock
and the Western North Atlantic Offshore stock have the potential to
occur in the project area. Because approximately 50 percent of the
[[Page 38126]]
project area occurs in waters shallower than 20 m, the isobaths at
which we expect segregation of these stocks (Garrison et al., 2017), we
assign take to each stock accordingly. Thus, we assume that 50 percent
of the total proposed authorized bottlenose dolphin takes would accrue
to the Western North Atlantic Offshore stock, and 50 percent to the
Western North Atlantic Northern Migratory Coastal stock (table 13).
Finally, takes by Level B harassment are modified to deduct the
proposed amount of take by Level A harassment in order to avoid double-
counting in the estimate of total takes for each species or stock.
Table 13--Take by Stock and Harassment Type and as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
Level B take Level A take Total take
Species Stock proposed for proposed for proposed for % Stock
authorization authorization authorization
----------------------------------------------------------------------------------------------------------------
North Atlantic Right Whale.... Western Atlantic 12 0 12 <3.2
Fin Whale..................... Western North 19 0 19 <1
Atlantic.
Humpback Whale................ Gulf of Maine... 29 4 33 <1
Minke Whale................... Canadian East 53 1 54 <1
Coast.
Sei Whale..................... Nova Scotia..... 7 0 7 <1
Pilot Whale, Long-finned...... Western N \1\ 14 0 14 <1
Atlantic.
Pilot Whale, Short-finned..... Western N
Atlantic.
Atlantic Spotted Dolphin...... Western N \1\ 25 0 25 <1
Atlantic.
Atlantic White-sided Dolphin.. Western N 62 0 62 <1
Atlantic.
Bottlenose Dolphin............ Western N 2,295 42 2,253 35
Atlantic
Migratory
Coastal.
Western N 2,296 42 2,254 3.5
Atlantic
Offshore.
Common Dolphin................ Western N 518 0 518 <1
Atlantic.
Harbor Porpoise............... Gulf of Maine/ 465 11 465 <1
Bay of Fundy.
Gray Seal..................... Western N 4,868 44 4,912 17.6
Atlantic.
Harbor Seal................... Western N 8
Atlantic.
Harp Seal..................... Western N <1
Atlantic.
----------------------------------------------------------------------------------------------------------------
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.
The mitigation requirements described in the following were
proposed by Transco in its adequate and complete application or are the
result of subsequent coordination between NMFS and Transco. Transco has
agreed that all of the mitigation measures are practicable. NMFS has
fully reviewed the specified activities and the mitigation measures to
determine if the mitigation measures would result in the least
practicable adverse impact on marine mammals and their habitat, as
required by the MMPA, and has determined the proposed measures are
appropriate. NMFS describes these below as proposed mitigation
requirements, and has included them in the proposed IHA.
Vessel Strike Avoidance Measures
In addition to complying with existing vessel speed restrictions
for North Atlantic right whales, Transco intends to comply with
voluntary programs NMFS uses to notify vessel operators to slow down to
avoid right whales. All project related vessels, regardless of size,
will operate at 10 knots (18.5 km/hr) or less when traveling in an SMA
(active in portions of the project area between November 1 and April
30). Additionally, at all times and locations, vessel operators and
crews would use the following protocols:
<bullet> Maintain a vigilant watch for right whales and slow down
or stop the vessel to avoid striking the animal(s);
<bullet> Conform to the regulations prohibiting approach of right
whales closer than 500 yards (460 m) (50 CFR 224.103 (c));
<bullet> Adhere to rules for DMAs if they are designated by NMFS in
the project area during the project.
Shutdown Zones
For all pile driving and removal activities, Transco would
implement shutdowns within designated zones. 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
vary based on the activity type and marine mammal hearing group (tables
14 and 15).
In cases where it would be challenging to detect marine mammals at
the Level A harassment isopleth, (e.g., all hearing groups during
impact pile driving activities), and where shutting down at the Level A
harassment zone
[[Page 38127]]
would create practicability concerns due to the distances at which
species would need to be detected (e.g., high frequency cetaceans
during impact pile driving), smaller shutdown zones have been proposed
(table 15)).
Construction supervisors and crews, PSOs, and relevant Transco
staff must avoid direct physical interaction with marine mammals during
construction activity. If a marine mammal comes within 10 m of such
activity, operations must cease and vessels must reduce speed to the
minimum level required to maintain steerage and safe working
conditions, as necessary to avoid direct physical interaction. 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 tables 14 and 15, or 15 minutes have passed without re-
detection of the animal.
Finally, 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 any harassment zone. If a marine
mammal species for which take is not authorized enters a harassment
zone, all in-water activities will cease until the animal leaves the
zone or has not been observed for at least 15 minutes. Pile driving
will proceed if the unauthorized species is observed leaving the
harassment zone or if 15 minutes have passed since the last
observation.
Table 14--Proposed Shutdown Zones During Vibratory Pile Driving and Removal
----------------------------------------------------------------------------------------------------------------
Shutdown for
all hearing
Site Pile size Installation or removal method groups,
(inches) install and
removal (m)
----------------------------------------------------------------------------------------------------------------
Morgan Shore Approach HDD (MP 12.59).......... 24 Vibratory....................... 10
36 Vibratory....................... 120
36, 36 Vibratory, Vibratory............ 60
48 Vibratory....................... 50
Neptune PC Crossing (MP 13.84)................ 10 Vibratory....................... 10
MP 14.5 to MP 16.5............................ 24 Vibratory....................... 20
MP 28.0 to MP 29.36........................... 34 Vibratory....................... 100
HDD Ambrose West Side (MP 29.4)............... 24 Vibratory....................... 10
36 Vibratory....................... 40
48 Vibratory....................... 80
36, 48 Vibratory, Vibratory............ 80
60 Vibratory....................... 120
HDD Ambrose East Side (MP 30.48).............. 24 Vibratory....................... 20
36 Vibratory....................... 40
48 Vibratory....................... 80
48, 48 Vibratory, Vibratory............ 80
60 Vibratory....................... 20
MP 34.5 to MP 35.04........................... 34 Vibratory....................... 30
Neptune PC Crossing (MP 35.04)................ 10 Vibratory....................... 10
----------------------------------------------------------------------------------------------------------------
Table 15--Proposed Shutdown Zones During Impact Pile Driving
[m]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hearing group-specific shutdown zones (m)
Location Pile types Activity ---------------------------------------------------------------
LF HF VHF PW
--------------------------------------------------------------------------------------------------------------------------------------------------------
HDD Morgan Offshore (MP 12.59)............ 36-inch Impact...................... 2000 200 200 150
36, 36 Impact, Impact..............
HDD Ambrose West Side (MP 29.4)........... 60 Impact......................
60, 48 Impact, Vibratory...........
MP 34.5 to MP 35.04....................... 34 Impact......................
--------------------------------------------------------------------------------------------------------------------------------------------------------
PSOs
The number and placement of PSOs during all construction activities
(described in the Proposed Monitoring and Reporting section) would
ensure that the shutdown zones are generally visible, such that PSOs
are reasonably confident of their ability to observe species at
relevant distances. Transco would employ at least two PSOs at each
active pile driving site during all pile driving activities.
Monitoring for Level A and Level B Harassment
PSOs would monitor the shutdown zones and beyond to the extent that
PSOs can see. Monitoring beyond the shutdown zones enables 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. Transco also plans to take measures beyond visual observations to
ensure that they are aware of marine mammal locations by monitoring
media throughout the day including, but not limited to, Whale Alert,
Whale Map, Right Whale Sightings Advisory System (RWSAS), and U.S.
Coast Guard very high
[[Page 38128]]
frequency (VHF) Channel 16 (see Monitoring and Reporting section).
Pre-and-Post-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 zones and as much of the harassment zones as
possible for a period of 30 minutes. Pre-start clearance monitoring
must be conducted during periods of visibility sufficient for the lead
PSO to determine that the shutdown zones are clear of marine mammals
for which take is authorized. If the shutdown zone for which take is
authorized is obscured by fog or poor lighting conditions, in-water
construction activity will not be initiated until the entire shutdown
zone is visible. 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 entering or
within shutdown zones, pile driving activity must be delayed or halted.
If pile driving is delayed or halted due to the presence of a marine
mammal, the activity may not commence or resume until either the animal
has voluntarily exited and been visually confirmed beyond the shutdown
zone or 15 minutes have passed without re-detection of the animal. If a
marine mammal for which take by Level B harassment is authorized is
present in the Level B harassment zone, activities may begin. If work
ceases for more than 30 minutes, the pre-activity monitoring of the
shutdown zones would commence.
Soft Start
The use of soft-start procedures during impact pile driving are
believed 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, with each strike
followed by a 30-second waiting period. This procedure would be
conducted a total of three times before impact pile driving begins.
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. Soft start is not required during
vibratory pile driving activities.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has preliminarily
determined that the proposed mitigation measures provide the means of
effecting the least practicable impact on the affected species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present 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 activity; 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.
The monitoring and reporting requirements described in the
following were proposed by Transco in its adequate and complete
application or are the result of subsequent coordination between NMFS
and Transco. Transco has agreed that all of the monitoring and
reporting measures are practicable. NMFS describes those below as
proposed requirements, and has included them in the proposed IHA.
Visual Monitoring
Marine mammal monitoring during pile driving activities must be
conducted by NMFS-approved PSOs in a manner consistent with the
following:
<bullet> PSOs must be independent of the activity contractor (for
example, employed by a subcontractor), and have no other assigned tasks
during monitoring periods;
<bullet> At least one PSO must 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 other relevant experience,
education (degree in biological science or related field) or training
for experience performing the duties of a PSO during construction
activities pursuant to NMFS-issued take authorization;
<bullet> Where a team of three or more PSOs is required, a lead
observer or monitoring coordinator will be designated. The lead
observer will be required to have prior experience working as a marine
mammal observer during construction activity pursuant to a NMFS-issued
incidental take authorization; and,
<bullet> PSOs must be approved by NMFS prior to beginning any
activity subject to this IHA.
PSOs should also have the following 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 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,
[[Page 38129]]
<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 trained PSOs positioned at
suitable vantage points to generally be able to observe the entirety of
the shutdown zones. Transco would place at least two PSOs at each
active pile driving site during all pile driving and removal
activities. PSOs would be stationed either on the construction barge or
a separate support vessel. PSOs would monitor for marine mammals 360
degrees around their respective vessels.
Monitoring would be conducted 30 minutes before, during, and 30
minutes after all in water construction activities. In addition, PSOs
will record all incidents of marine mammal occurrence, regardless of
distance from activity, and will 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.
North Atlantic Right Whale and Other Marine Mammal Awareness
Throughout each day, Transco plans to use available sources of
information on North Atlantic right whale and other marine mammals,
including but not limited to Whale Alert, Whale Map, RWSAS, and U.S.
Coast Guard very high frequency (VHF) Channel 16, to receive
notifications of any marine mammal sightings and information associated
with any DMAs. Maintaining frequent daily awareness of North Atlantic
right whale presence in the area, through Transco's ongoing visual
monitoring efforts and opportunistic data sources (outside of Transco's
efforts), and subsequent coordination for disseminating that
information across project personnel affords increased protection of
North Atlantic right whales and other marine mammals by alerting
project personnel and the marine mammal monitoring team to a higher
likelihood of encountering these species, potentially increasing the
efficacy of mitigation efforts.
Reporting
Transco 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 will include an overall
description of work completed, a narrative regarding marine mammal
sightings, and associated PSO data sheets. Specifically, the report
will 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 or vibratory); and (2) total
duration of driving time for each pile (vibratory driving) and number
of strikes for each pile (impact driving);
<bullet> PSO locations during marine mammal monitoring;
<bullet> Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and other relevant weather
conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance;
<bullet> Upon observation of a marine mammal, the following
information: (1) name of PSO who sighted the animal(s) and PSO location
and activity at time of sighting; (2) time of sighting; (3)
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; (4)
distance and location of each observed marine mammal relative to the
pile being driven for each sighting; (5) estimated number of animals
(min/max/best estimate); (6) estimated number of animals by cohort
(adults, juveniles, neonates, group composition, etc.); (7) animal's
closest point of approach and estimated time spent within the
harassment zone; (8) 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 specific
actions that ensued, and resulting changes in behavior of the
animal(s), if any.
A final report must be prepared and submitted within 30 calendar
days following receipt of any NMFS comments on the draft report. If no
comments are received from NMFS within 30 calendar days of receipt of
the draft report, the report shall be considered final. All PSO data
would be submitted electronically in a format that can be queried such
as a spreadsheet or database and 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, the Transco must report the
incident to the NMFS Office of Protected Resources (OPR)
(<a href="/cdn-cgi/l/email-protection#3f6f6d11766b6f11725051564b504d5651586d5a4f504d4b4c7f51505e5e11585049"><span class="__cf_email__" data-cfemail="09595b27405d5927446667607d667b60676e5b6c79667b7d7a4967666868276e667f">[email protected]</span></a> and <a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="a0c9d4d08ec6ccc5cdc9cec7e0cecfc1c18ec7cfd6">[email protected]</a>) and
Greater Atlantic Regional Fisheries Office (GARFO) Stranding
Coordinator as soon as feasible. If the death or injury was clearly
caused by the specified activity, the Transco must immediately cease
the activities until NMFS OPR is able to review the circumstances of
the incident and determine what, if any, additional measures are
appropriate to ensure compliance with the terms of this IHA. Transco
must not resume their activities until notified by NMFS. The report
must include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animals(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and,
<bullet> General circumstances under which the animal was
discovered.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical
[[Page 38130]]
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 and removal associated with this project, as outlined
previously, have the potential to disturb or displace marine mammals.
Specifically, the specified activities may result in take, in the form
of Level B harassment and, for some species, Level A harassment from
underwater sounds generated by pile driving and removal. Potential
takes could occur if individuals are present in the ensonified zone
when these activities are underway.
No serious injury or mortality is expected, even in the absence of
required mitigation measures, given the nature of the activities.
Further, for eight species of marine mammals, no take by Level A
harassment is anticipated, due to the rarity of the species near the
project area. The likelihood of take by Level A harassment occurring is
further reduced by Transco's plans to implement mitigation measures
such as shutdown zones that encompass all or a portion of the Level A
harassment zones (see Proposed Mitigation section).
Level A harassment is proposed to be authorized for humpback whale,
minke whale, bottlenose dolphin, harbor porpoise, and pinnipeds that
may occur in the project area (gray seal, harbor seal, and harp seal).
Any take by Level A harassment is expected to arise from, at most, a
small degree of AUD INJ (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.
Additionally, the amount of take by Level A harassment proposed for
authorization is very low. NMFS expects no more than 4 takes by Level A
harassment for humpback whale; 1 take by Level A harassment for minke
whale; and 11 takes by Level A harassment for harbor porpoise. The
proposed amount of take by Level A harassment for bottlenose dolphin
and the guild of pinnipeds that may occur in the project area are a bit
larger--42 takes and 44 takes, respectively. However, for all hearing
groups, if hearing impairment occurs, it is most likely that the
affected animal would lose only a few dB in its hearing sensitivity.
Due to the small degree anticipated, any AUD INJ potentially 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.
Effects on individuals that are taken by Level B harassment in the
form of 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.
Some individual marine mammals in the project area, such as harbor
seals or bottlenose dolphins, may be present and be subject to repeated
exposure to sound from pile driving activities on multiple days.
However, pile driving and extraction is not expected to occur on every
day, and these individuals would likely return to normal behavior
during gaps in pile driving activity within each day of construction
and in between work days. As discussed above, individuals could
temporarily relocate during construction activities to reduce exposure
to elevated sound levels from the project. Thus, even repeated Level B
harassment of some small subset of an overall stock is unlikely to
result in any effects on rates of reproduction and survival of the
stock.
The project is also not expected to have significant adverse
effects on affected marine mammals' habitats. The project activities
would not modify existing marine mammal habitat for a significant
amount of time. The activities may cause a low level of turbidity in
the water column and some fish may leave the area of disturbance, thus
temporarily impacting marine mammals' foraging opportunities in a
limited portion of the foraging range; but, because of the short
duration of the activities and the relatively small area of the habitat
that may be affected (with the exception of right whales, there are no
habitats of known particular importance to marine mammals), the impacts
to marine mammal habitat are not expected to cause significant or long-
term negative consequences.
There is a BIA for migrating right whales that intersects with the
offshore portion of the project area (LaBrecque et al., 2015; Van
Parijs et al., 2015), but it is active between March and April and
November and December, when most of the project activities are not
planned to occur. This suggests that impacts from the project would
have minimal to no impact on important right whale habitat and would
therefore not affect reproduction and survival. While there are plans
for project activities to occur
[[Page 38131]]
in November, and Transco has also accounted for the potential that the
project schedule could shift into any time of year, most of the North
Atlantic right whales observed in the New York Bight, when present, are
detected in deeper waters of the continental shelf, much further
offshore (Zoidis et al., 2021; Morrison and Taggart, 2021, accessed
July 25, 2025). Given the nature of migratory behavior (e.g.,
continuous path), as well as the low number of total takes, we
anticipate that few, if any, of the instances of take would represent
repeat takes of any individual.
As described above, North Atlantic right, humpback, and minke
whales are experiencing ongoing UMEs, and an ongoing UME for gray and
harbor seals is pending closure. However, we do not expect authorized
takes to exacerbate or compound upon these ongoing and closure pending
UMEs. As discussed above, very little injury, serious injury or
mortality is expected or authorized, and the impact of Level A and
Level B harassment takes of these species will be minimized through the
incorporation of mitigation measures. The UMEs do not provide cause for
concern regarding population-level impacts. Despite the UMEs, the
relevant population of humpback whales (the West Indies breeding
population, or DPS), minke whales, and relevant pinniped species (gray
and harbor seals) remain healthy.
For North Atlantic right whales, no injury as a result of the
proposed project is expected or proposed for authorization, and Level B
harassment takes of right whales are expected to be in the form of
avoidance of the immediate area of construction. In addition, the
number of exposures above the Level B harassment threshold are minimal
(i.e., 12). As no injury or mortality is expected or proposed for
authorization, the proposed authorized takes of right whales would not
exacerbate or compound the ongoing UME in any way.
Finally, it is unlikely that minor noise effects in a small,
localized area of habitat would have any effect on the reproduction or
survival of any individuals, much less these stocks' annual rates of
recruitment or survival. In combination, we believe that these factors,
as well as the available body of evidence from other similar
activities, demonstrate that the potential effects of the specified
activities would have only minor, short-term effects on individuals.
The specified activities are not expected to impact rates of
recruitment or survival and would therefore not result in population-
level impacts.
In summary and as described above, the following factors primarily
support our preliminary determination that the impacts resulting from
this activity are not expected to adversely affect any of the species
or stocks through effects on annual rates of recruitment or survival:
<bullet> No serious injury or mortality is anticipated or
authorized;
<bullet> No take by Level A harassment is proposed for 7 species;
<bullet> Take by Level A harassment would be in very small amounts
for most species and of low severity;
<bullet> Proposed takes by Level B harassment are relatively low
for most stocks. Level B harassment would primarily be in the form of
behavioral disturbance, resulting in avoidance of the project areas
around where impact or vibratory pile driving is occurring, with some
low-level TTS that may limit the detection of acoustic cues for
relative
[…truncated; see source link]Indexed from Federal Register on August 7, 2025.
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