Proposed Rule2023-27189
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Maryland Offshore Wind Project Offshore of Maryland
Primary source
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Published
January 4, 2024
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from US Wind, Inc., (US Wind) for Incidental Take Regulations (ITR) and an associated Letter of Authorization (LOA) pursuant to the Marine Mammal Protection Act (MMPA). The requested regulations would govern the authorization of take, by Level A harassment and Level B harassment, of small number of marine mammals over the course of 5 years (2025-2029) incidental to construction of the Maryland Offshore Wind Project offshore of Maryland within the Bureau of Ocean Energy Management (BOEM) Commercial Lease of Submerged Lands for Renewable Energy Development on the Outer Continental Shelf (OCS) Lease Area OCS-A 0490 (Lease Area) and associated Export Cable Routes. Project activities likely to result in incidental take include impact pile driving and site assessment surveys using high-resolution geophysical (HRG) equipment. NMFS requests comments on its proposed rule. NMFS will consider public comments prior to making any final decision on the promulgation of the requested ITR and issuance of the LOA; agency responses to public comments will be summarized in the final notice of our decision. The proposed regulations, if issued, would be effective January 1, 2025 through December 31, 2029.
Full Text
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[Federal Register Volume 89, Number 3 (Thursday, January 4, 2024)]
[Proposed Rules]
[Pages 504-587]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-27189]
[[Page 503]]
Vol. 89
Thursday,
No. 3
January 4, 2024
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Part 217
Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to the Maryland Offshore Wind Project
Offshore of Maryland; Proposed Rule
Federal Register / Vol. 89 , No. 3 / Thursday, January 4, 2024 /
Proposed Rules
[[Page 504]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 217
[Docket No. 231206-0289]
RIN 0648-BM32
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Maryland Offshore Wind Project
Offshore of Maryland
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Proposed rule; request for comments.
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SUMMARY: NMFS has received a request from US Wind, Inc., (US Wind) for
Incidental Take Regulations (ITR) and an associated Letter of
Authorization (LOA) pursuant to the Marine Mammal Protection Act
(MMPA). The requested regulations would govern the authorization of
take, by Level A harassment and Level B harassment, of small number of
marine mammals over the course of 5 years (2025-2029) incidental to
construction of the Maryland Offshore Wind Project offshore of Maryland
within the Bureau of Ocean Energy Management (BOEM) Commercial Lease of
Submerged Lands for Renewable Energy Development on the Outer
Continental Shelf (OCS) Lease Area OCS-A 0490 (Lease Area) and
associated Export Cable Routes. Project activities likely to result in
incidental take include impact pile driving and site assessment surveys
using high-resolution geophysical (HRG) equipment. NMFS requests
comments on its proposed rule. NMFS will consider public comments prior
to making any final decision on the promulgation of the requested ITR
and issuance of the LOA; agency responses to public comments will be
summarized in the final notice of our decision. The proposed
regulations, if issued, would be effective January 1, 2025 through
December 31, 2029.
DATES: Comments and information must be received no later than February
5, 2024.
ADDRESSES: Submit all electronic public comments via the Federal e-
Rulemaking Portal. Go to <a href="https://www.regulations.gov">https://www.regulations.gov</a> and enter NOAA-
NMFS-2023-0110 in the Search box. (note: copying and pasting the FDMS
Docket Number directly from this document may not yield search
results). Click on the ``Comment'' icon, complete the required fields,
and enter or attach your comments.
Instructions: Comments sent by any other method, to any other
address or individual, or received after the end of the comment period,
may not be considered by NMFS. All comments received are a part of the
public record and will generally be posted for public viewing on
<a href="https://www.regulations.gov">https://www.regulations.gov</a> without change. All personal identifying
information (e.g., name, address), confidential business information,
or otherwise sensitive information submitted voluntarily by the sender
will be publicly accessible. NMFS will accept anonymous comments (enter
``N/A'' in the required fields if you wish to remain anonymous).
FOR FURTHER INFORMATION CONTACT: Jessica Taylor, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Availability
A copy of US Wind's Incidental Take Authorization (ITA) 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-other-energy-activities-renewable">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-other-energy-activities-renewable</a>. In case of
problems accessing these documents, please call the contact listed
above (see FOR FURTHER INFORMATION CONTACT).
Purpose and Need for Regulatory Action
This proposed rule would provide a framework under the authority of
the MMPA (16 U.S.C. 1361 et seq.) to allow for the authorization of
take of marine mammals incidental to construction of the Maryland
Offshore Wind Project (hereafter, ``Project'') within the BOEM
Renewable Energy Development Lease Area and along export cable
corridors to landfall locations in Delaware. NMFS received a request
from US Wind for 5-year regulations and a LOA that would authorize take
of individuals of 19 species of marine mammals (5 species by Level A
harassment and Level B harassment and 14 species by Level B harassment
only), comprising 20 stocks, incidental to US Wind's construction
activities. No mortality or serious injury is anticipated or proposed
for authorization. Please see below for definitions of harassment.
Please see the Estimated Take of Marine Mammals section below for
definitions of relevant terms.
Legal Authority for the Proposed Action
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made, regulations are
promulgated (when applicable), and public notice and an opportunity for
public comment are provided.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, the availability of the species or stocks for taking for
certain subsistence uses (referred to as ``mitigation''), and
requirements pertaining to the mitigation, monitoring and reporting of
the takings are set forth.
As noted above, no serious injury or mortality is anticipated or
proposed for authorization in this proposed rule. Relevant definitions
of MMPA statutory and regulatory terms are included below:
<bullet> Citizen--individual U.S. citizens or any corporation or
similar entity if it is organized under the laws of the United States
or any governmental unit defined in 16 U.S.C. 1362(13) (50 CFR
216.103);
<bullet> Take--to harass, hunt, capture, or kill, or attempt to
harass, hunt, capture, or kill any marine mammal (16 U.S.C. 1362; 50
CFR 216.3);
<bullet> Incidental taking--an accidental taking. This does not
mean that the taking is unexpected, but rather it includes those
takings that are infrequent, unavoidable, or accidental (50 CFR
216.103);
<bullet> Serious injury--any injury that will likely result in
mortality (50 CFR 216.3);
<bullet> Level A harassment--any act of pursuit, torment, or
annoyance which has the potential to injure a marine mammal or marine
mammal stock in the wild (16 U.S.C. 1362); and
<bullet> Level B harassment--any act of pursuit, torment, or
annoyance which has the potential to disturb a marine
[[Page 505]]
mammal or marine mammal stock in the wild by causing disruption of
behavioral patterns, including, but not limited to, migration,
breathing, nursing, breeding, feeding, or sheltering (16 U.S.C. 1362).
Section 101(a)(5)(A) of the MMPA and the implementing regulations
at 50 CFR part 216, subpart I, provide the legal basis for proposing
and, if appropriate, issuing 5-year regulations and associated LOA.
This proposed rule also establishes required mitigation, monitoring,
and reporting requirements for US Wind's activities.
Summary of Major Provisions Within the Proposed Action
The major provisions within this proposed rule are as follows:
<bullet> Authorize take of marine mammals by Level A harassment
and/or Level B harassment;
<bullet> No mortality or serious injury of any marine mammal is
proposed to be authorized;
<bullet> Establish a seasonal moratorium on pile driving during the
months of highest North Atlantic right whale (Eubalaena glacialis)
presence in the project area (December 1-April 30);
<bullet> Require both visual and passive acoustic monitoring by
trained, NMFS-approved Protected Species Observers (PSOs) and Passive
Acoustic Monitoring (PAM) operators before, during, and after impact
pile driving and HRG surveys;
<bullet> Require training for all US Wind personnel that would
clearly articulate all relevant responsibilities, communication
procedures, marine mammal monitoring and mitigation protocols,
reporting protocols, safety, operational procedures, and requirements
of the ITA and ensure that all requirements are clearly understood by
all participating parties;
<bullet> Require the use of sound attenuation device(s) during all
foundation installation activities to reduce noise levels;
<bullet> Delay the start of foundation installation if a North
Atlantic right whale is observed at any distance by a PSO or
acoustically detected within certain distances;
<bullet> Delay the start of foundation installation if other marine
mammals are observed entering or within their respective clearance
zones;
<bullet> Shut down pile driving (if feasible) if a North Atlantic
right whale is observed or if other marine mammals enter their
respective shut down zones;
<bullet> Shut down HRG survey equipment that may impact marine
mammals if a marine mammal enters their respective shut down zones;
<bullet> Conduct sound field verification during impact pile
driving to ensure in situ noise levels are not exceeding those modeled;
<bullet> Implement soft starts for impact pile driving;
<bullet> Implement ramp-up for HRG site characterization survey
equipment;
<bullet> Increase awareness of North Atlantic right whale presence
through monitoring of the appropriate networks and very high-frequency
(VHF) Channel 16, as well as reporting any sightings to the sighting
network;
<bullet> Implement various vessel strike avoidance measures;
<bullet> Implement Best Management Practices (BMPs) during
fisheries monitoring surveys, such as removing gear from the water if
marine mammals are considered at-risk or are interacting with gear; and
<bullet> Require frequent scheduled and situational reporting
including, but not limited to, information regarding activities
occurring, marine mammal observations and acoustic detections, and
sound field verification monitoring results.
Under section 105(a)(1) of the MMPA, failure to comply with these
requirements or any other requirements in a regulation or permit
implementing the MMPA may result in civil monetary penalties. Pursuant
to 50 CFR 216.106, violations may also result in suspension or
withdrawal of the LOA for the project. Knowing violations may result in
criminal penalties under section 105(b) of the MMPA.
National Environmental Policy Act (NEPA)
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 evaluate the proposed action (i.e., promulgation of
regulations and subsequent issuance of a 5-year LOA) and alternatives
with respect to potential impacts on the human environment.
Accordingly, NMFS plans to adopt the BOEM Environmental Impact
Statement (EIS), provided our independent evaluation of the document
finds that it includes adequate information analyzing the effects of
promulgating the proposed regulations and LOA issuance on the human
environment. NMFS is a cooperating agency on BOEM's EIS. BOEM's draft
EIS, ``Maryland Offshore Wind Project Draft Environmental Impact
Statement (DEIS) for Commercial Wind Lease OCS-A 0490'', was made
available for public comment on October 6, 2023 (88 FR 69658) and is
available at <a href="https://www.boem.gov/renewable-energy/state-activities/maryland-offshore-wind">https://www.boem.gov/renewable-energy/state-activities/maryland-offshore-wind</a>. The DEIS had a 45-day public comment period
open from October 6, 2023 to November 20, 2023. Additionally, BOEM held
two in-person public meetings on October 24, 2023 in Ocean City,
Maryland and October 26, 2023 in Dagsboro, Delaware and two virtual
public meetings on October 19, 2023 and October 30, 2023.
Information contained within US Wind's ITA application and this
Federal Register document provide the environmental information related
to these proposed regulations and associated 5-year LOA for public
review and comment. NMFS will review all comments submitted in response
to this notice of proposed rulemaking prior to concluding the NEPA
process or making a final decision on the requested 5-year ITR and LOA.
Fixing America's Surface Transportation Act (FAST-41)
This project is covered under Title 41 of the Fixing America's
Surface Transportation Act, or ``FAST-41.'' FAST-41 includes a suite of
provisions designed to expedite the environmental review for covered
infrastructure projects, including enhanced interagency coordination as
well as milestone tracking on the public-facing Permitting Dashboard.
FAST-41 also places a 2-year limitations period on any judicial claim
that challenges the validity of a Federal agency decision to issue or
deny an authorization for a FAST-41 covered project (42 U.S.C. 4370m-
6(a)(1)(A)).
US Wind's proposed project is listed on the Permitting Dashboard.
Milestones and schedules related to the environmental review and
permitting for the US Wind's Maryland Offshore Wind Project can be
found at <a href="https://www.permits.performance.gov/permitting-project/maryland-offshore-wind-project">https://www.permits.performance.gov/permitting-project/maryland-offshore-wind-project</a>.
Summary of Request
On August 31, 2022, NMFS received a request from US Wind, a
Baltimore, Maryland-based company registered in the State of Delaware
and subsidiary of Renexia SpA, for the promulgation of regulations and
issuance of an associated 5-year LOA to take marine mammals incidental
to construction activities associated with implementation of the
Project offshore of Maryland in the BOEM Lease Area OCS-A 0490 and
associated export cable routes. The request was for the incidental, but
not intentional, taking of a small number of 19 marine mammal species
(comprising 20 stocks). Neither
[[Page 506]]
US Wind nor NMFS expects serious injury or mortality to result from the
specified activities nor is any proposed for authorization.
US Wind is proposing to develop the Project over the course of
three construction campaigns. In total, the 3 campaigns would result in
a maximum of 114 wind turbine generators (WTGs), 4 offshore substations
(OSS) positions, and 1 Meteorological tower (Met tower) within the
Lease Area. The initial construction campaign, MarWin, would include
installation of approximately 21 WTGs, 1 OSS, and cable landing
infrastructure during the first year of activities in the most eastern
part of the Lease Area. The second construction campaign, Momentum
Wind, would take place during the second year of construction
activities and include installation of approximately 55 WTGs, 2 OSSs,
and a Met tower immediately to the west of MarWin. The third
construction campaign, currently unnamed and referred to as Future
Development, would occur during the third year of construction
activities and include the installation of approximately 38 WTGs and 1
OSS in the most western portion of the Lease Area. Four offshore export
cables would transmit electricity generated by the WTGs from the Lease
Area to onshore transmission systems within Delaware Seashore State
Park.
In response to our comments and following extensive information
exchanges with NMFS, US Wind submitted a final, revised application on
March 31, 2023 that NMFS deemed adequate and complete on April 3, 2023.
The final version of the application is available on NMFS' website at:
<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-wind-inc-construction-and-operation-maryland-offshore-wind">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-wind-inc-construction-and-operation-maryland-offshore-wind</a>. On May 2,
2023, NMFS published a notice of receipt (NOR) of the adequate and
complete application in the Federal Register (88 FR 27463), requesting
comments and soliciting information related to US Wind's request during
a 30-day public comment period. During the NOR public comment period,
NMFS received comment letters from 77 private citizens, 6 non-
governmental organizations, and 1 state government organization
(Delaware Department of Natural Resources and Environmental Control).
NMFS has reviewed all submitted material and has taken these into
consideration during the drafting of this proposed rule.
On August 1, 2022, NMFS announced proposed changes to the existing
North Atlantic right whale vessel speed regulations (87 FR 46921,
August 1, 2022) to further reduce the likelihood of mortalities and
serious injuries to endangered right whales from vessel collisions,
which are a leading cause of the species' decline and a primary factor
in an ongoing Unusual Mortality Event (UME). Should a final vessel
speed rule be issued and become effective during the effective period
of this ITR (or any other MMPA incidental take authorization), the
authorization holder would be required to comply with any and all
applicable requirements contained within the final rule. Specifically,
where measures in any final vessel speed rule are more protective or
restrictive than those in this or any other MMPA authorization,
authorization holders would be required to comply with the requirements
of the rule. Alternatively, where measures in this or any other MMPA
authorization are more restrictive or protective than those in any
final vessel speed rule, the measures in the MMPA authorization would
remain in place. The responsibility to comply with the applicable
requirements of any vessel speed rule would become effective
immediately upon the effective date of any final vessel speed rule and
when notice is published on the effective date, NMFS would also notify
US Wind if the measures in the speed rule were to supersede any of the
measures in the MMPA authorization such that they were no longer
required.
On September 6, 2023, and September 11, 2023, US Wind submitted
supplemental information related to its pilot whale and seal take
analyses. The corresponding memos, entitled ``US Wind NMFS Request for
Information (RFI) Response Memo and Maryland Offshore Wind Project
Revised Requested Take Tables'' are available on our website.
Description of the Specified Activities
Overview
US Wind has proposed to construct and operate a wind energy
facility, the Project, in the Atlantic Ocean in lease area OCS-A 0490,
offshore Maryland. The Project would allow the State of Maryland to
advance Federal and State offshore wind targets as well as reduce
greenhouse gas emissions, increase grid reliability, and support
economic development growth in the region. The Project consists of
three construction campaigns including MarWin, located in the
southeastern portion of the Lease Area with the potential to generate
approximately 300 megawatts (MW) of energy, Momentum Wind, located
immediately west of MarWin with the potential to generate approximately
808 MW of energy, and Future Development, which encompasses buildout of
the remainder of the Lease Area and for which generation capacity has
yet to be determined. Once operational, MarWin and Momentum Wind would
advance the State of Maryland's renewable energy goals of 50 percent by
the year 2030, with the full buildout of the Lease Area further
achieving renewable energy targets. US Wind also anticipates completing
the Future Development campaign within the effective period of the
proposed rule.
The Project would consist of several different types of permanent
offshore infrastructure, including up to 114 WTGs (e.g., 18-MW model
with a 250-meter (m) rotor diameter platform), four OSSs, a Met tower,
and inter-array and export cables. The Project is divided into three
construction campaigns: MarWin, Momentum Wind, and Future Development
(table 1). MarWin would occupy approximately 46.6 km\2\ (11,515 acres)
which would include approximately 21 WTGs and 1 OSS. The MarWin
campaign, as well as subsequent Momentum Wind and Future Development,
includes monopiles as the one potential WTG foundation type. For each
campaign, the OSS would be supported by monopiles or jacket foundations
with skirt piles. Skirt piles are post-piled pin piles. Jacket
foundations are placed on the seabed and pin piles are driven into
jacket pile guides, which are known as skirts. Table 1 provides a
summary of each construction campaign.
Table 1--US Wind's Anticipated Construction Campaign Schedule
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Number of 11-m Number of 1.8-
Campaigns Construction monopiles for Number 3-m pin piles for m pin piles Onshore export Offshore
year WTGs OSS jacket foundations \1\ for Met tower cables substations
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MarWin................................... 1 (2025) 21 4 (1 jacket)............... 0 4 1
Momentum................................. 2 (2026) 55 8 (2 jackets).............. 3 0 2
[[Page 507]]
Future Development....................... 3 (2027) 38 4 (1 jacket)............... 0 0 1
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\1\ Potential OSS foundations could also include monopile and suction bucket jacket foundations.
Strings of WTGs will connect with the OSS via a submarine inter-
array cable transmission system. Up to four high-voltage alternating
current (HVAC) offshore export cables would be installed during the
MarWin campaign, spanning approximately 65-97 km (40-60 miles (mi)) in
length, dependent on the location of the OSS and the final routing. The
Export Cable Corridor (ECC) would transmit electricity from the OSS to
one or two landfall sites in Delaware Seashore State Park.
The second construction campaign, Momentum Wind, would contain
approximately 55 WTGs, 2 OSSs, and 1 Met tower within an area of
approximately 142.4 km\2\ (35,188 acres). The Met tower would be
supported by pin pile foundations. During the third construction
campaign, Future Development, approximately 38 WTGs and 1 OSS would be
installed within an area of approximately 80.3 km\2\ (19,843 acres).
US Wind plans to install all monopile or pin pile foundations via
impact pile driving. If suction bucket foundations are selected for OSS
jacket foundations, impact pile driving would not be necessary. US Wind
would also conduct the following supporting activities: temporary
installation and subsequent removal of gravity cells to connect the
offshore export cables to onshore facilities; permanently install scour
protection around all foundations; permanently install and perform
trenching, laying, and burial activities associated with the export
cables from the OSSs to shore-based switching and sub-stations and WTG
inter-array cables; and, during years 2 and 3, performance of HRG
surveys using active acoustic sources with frequencies of less than 180
kilohertz (kHz). Vessels would transit within the project area and
anticipated between ports (Port Norris, NJ; Lewes, DE; Ocean City, MD;
Baltimore, MD; Hampton Roads, VA; and Cape Charles, VA) and the Lease
Area and cable corridors to transport crew, supplies, and materials to
support construction activities.
Up to four offshore export cables would be located among up to two
corridors from the OSSs and connect to the planned landfall at either
3R's Beach or Tower Road within Delaware Seashore State Park. When the
cables reach the landfall site, they would be pulled into a cable duct
generated by horizontal directional drilling (HDD), which would route
the cables under the existing beach to subterranean transition vaults.
All offshore cables would be connected to onshore export cables at the
sea-to-shore transition point via trenchless installation (i.e.,
underground tunneling utilizing micro tunnel boring installation
methodologies).
Fishery monitoring surveys, performed via recreational boat-based
surveys and a pot-based monitoring approach using ropeless gear
technology, would be conducted in conjunction with the University of
Maryland Center for Environmental Science (UMCES) to enhance existing
data for specific benthic and pelagic species of concern.
Dates and Duration
As described above, US Wind would conduct 3 campaigns over 3 years:
MarWin, Momentum Wind, and Future Development (table 1). In case of any
delays to any campaign, NMFS is proposing a 5-year effective date of
the proposed regulations and LOA; however, no more work in any given
year or total over 5 years other than described here would occur. US
Wind anticipates that activities with the potential to result in
incidental take of marine mammals would occur throughout 3 of the 5
years (2025-2027) of the proposed regulations which, if issued, would
be effective from January 1, 2025 through December 31, 2029. Based on
US Wind's proposed schedule, the installation of all permanent
structures would be completed by the end of November 2027. More
specifically, US Wind would install piles only between May 1 and
November 30. Also, the installation of WTG foundations and OSS 3-m pin
pile jacket foundations is expected to occur during daylight hours
between May 1 and November 30 of 2025, 2026, and 2027 (table 2);
however, NMFS is proposing to allow nighttime pile driving if US Wind
submits, and NMFS approves, an Alternative Monitoring Plan, as
discussed below. The single Met tower foundation would be installed in
2026 (table 2).
US Wind anticipates HRG surveys using sparkers and boomers to occur
during 2026 and 2027. Up to 14 days of HRG survey activity are planned
from April through June 2026 during the Momentum campaign. In addition,
up to 14 days of HRG survey activity are planned from April through
June 2027 during the Future Development campaign. No HRG surveys using
equipment that has the potential to result in the harassment of marine
mammals (e.g., sparkers or boomers) are planned for the MarWin campaign
during year 1.
Table 2--US Wind's Anticipated Construction and Operations Schedule During the Effective Period of the LOA \1\
----------------------------------------------------------------------------------------------------------------
Expected duration
Project activity Construction campaign Expected timing \2\ (approximate)
----------------------------------------------------------------------------------------------------------------
Scour Protection Pre-Installation MarWin............................. Year 1: Q2 through 21 days.
Q3 of 2025.
Momentum Wind...................... Year 2: Q2 through 55 days.
Q3 of 2026.
Future Development................. Year 3: Q2 through 38 days.
Q3 of 2027.
WTG Foundation Installation 3 5.. MarWin............................. Year 1: June 21 days.
through September
of 2025.
Momentum Wind...................... Year 2: May through 55 days.
August of 2026.
Future Development................. Year 3: June 38 days.
through August of
2027.
Scour Protection Post- MarWin............................. Year 1: Q2 through 42 days.
Installation. Q3 of 2025.
Momentum Wind...................... Year 2: Q2 through 110 days.
Q3 of 2026.
Future Development................. Year 3: Q2 through 76 days.
Q3 of 2027.
OSS Foundation Installation 3 5.. MarWin............................. Year 1: July of 1 day.
2025.
[[Page 508]]
Momentum Wind...................... Year 2: July of 2 days.
2026.
Future Development................. Year 3: July of 1 day.
2027.
Met Tower Installation 3 4....... Momentum Wind...................... Year 2: June of 1 day.
2026.
HRG Surveys \5\.................. Momentum Wind...................... Year 2: Q2 through 14 days.
Q3 of 2026.
Future Development................. Year 3: Q2 through 14 days.
Q3 of 2027.
Site Preparation................. n/a................................ Not anticipated.... n/a.
Inter-array Cable Installation... Marwin............................. Year 1: Q2 through 42 days.
Q4 of 2025.
Momentum Wind...................... Year 2: Q2 through 110 days.
Q4 of 2026.
Future Development................. Year 3: Q2 through 76 days.
Q4 of 2027.
Export Cable Installation........ MarWin............................. Year 1: Q1 through 60 days.
Q4 of 2025.
Momentum Wind...................... Year 2: Q1 through 120 days (2
Q4 of 2026. cables).
Future Development................. Year 3: Q1 through 60 days.
Q4 of 2027.
Fishery Monitoring Surveys....... MarWin............................. Q1 through Q4 Years 16 days/year for
1-5. commercial pot
surveys.
Momentum Wind...................... 12 days/year for
Future Development................. recreational
surveys.
----------------------------------------------------------------------------------------------------------------
\1\ While the effective period of the proposed regulations would extend through December 31, 2029, no activities
are proposed to occur in 2028 or 2029 by US Wind so these were not included in this table.
\2\ Installation timing will depend on vessel availability, contractor selection, weather, and more. Year 1 is
anticipated to be 2025, year 2 to be 2026, and year 3 to be 2027, although these are subject to change per the
factors identified. Note: ``Q1, Q2, Q3, and Q4'' each refer to a quarter of the year, starting in January and
comprising 3 months each. Therefore, Q1 represents January through March, Q2 represents April through June, Q3
represents July through September, and Q4 represents October through December.
\3\ The months identified here represent US Wind's planned schedule; however, in case of unanticipated delays,
foundation installation may occur between May 1 and November 30 annually.
\4\ US Wind anticipates that all WTGs, OSS, and Met tower foundations will be installed by November 30, 2027;
however, unanticipated delays may require some foundation pile driving to occur in years 4 (2028) or 5 (2029).
\5\ Represents HRG surveys that may result in take of marine mammals. US Wind plans to conduct HRG surveys that
do not have the potential to result in take of marine mammals during Q2 through Q3 of year 1 given those
surveys would utilize equipment all operating over 180kHz or have no acoustic output.
Specific Geographic Region
US Wind's specified activities would occur within the Northeast
U.S. Continental Shelf Large Marine Ecosystem (NES LME), an area of
approximately 260,000 km\2\ (64,247,399.2 acres) from Cape Hatteras in
the south to the Gulf of Maine in the north. Specifically, the
specified geographic region is the Middle-Atlantic Bight (Mid-Atlantic
Bight) sub-area of the NES LME. The Mid-Atlantic Bight encompasses
waters of the Atlantic Ocean between Cape Hatteras, North Carolina and
Martha's Vineyard, Massachusetts, extending westward into the Atlantic
to the 100-m isobath. In the Mid-Atlantic Bight, the pattern of
sediment distribution is relatively simple. The continental shelf south
of New England is broad and flat, dominated by fine grained sediments.
Most of the surficial sediments on the continental shelf are sands and
gravels. Silts and clays predominate at and beyond the shelf edge, with
most of the slope being 70-100 percent mud. Fine sediments are also
common in the shelf valleys leading to the submarine canyons. There are
some larger materials, left by retreating glaciers, along the coast of
Long Island and to the north and east.
Primary productivity is highest in the nearshore and estuarine
regions, with coastal phytoplankton blooms initiating in the winter and
summer, although the timing and spatial extent of blooms varies from
year to year. The relatively productive continental shelf supports a
wide variety of fauna and flora, making it important habitat for
various benthic and fish species and marine mammals, including but not
limited to, fin whales, humpback whales, North Atlantic right whales,
and other large whales as they migrate through the area. The Cold Pool,
a bottom-trapped cold, nutrient-rich pool and distinct oceanographic
feature of the Mid-Atlantic Bight, creates habitat that provides
thermal refuge to cold water species in the area (Lentz, 2017). Cold
Pool waters, when upwelled to the surface, promote primary productivity
within this region (Voynova et al., 2013).
The seafloor in the Project Area is dynamic and changes over time
due to current, tidal flows, and wave conditions. As the Lease Area is
located just south of the mouth of Delaware Bay, the seafloor bedforms
and sediments are affected by interactions between storm-driven
currents, storm discharges from Delaware Bay, and tidal flows
associated with Delaware Bay (US Wind, 2023b). The Lease Area is
defined by medium-coarse grained sand at the surface and sub-surface
interlays of clay and gravel (Alpine, 2015). The most prominent
bathymetric features of the Lease Area are ridges and swales offshore
of the Delmarva Peninsula that extend seaward from Delaware Bay (US
Wind, 2023b). Sand ripples are present throughout the Project area.
Sediment within the onshore export cable corridor is composed of
predominantly silt-sand mixed with medium-coarse grained sand (US Wind,
2023b). The bottom habitat of Indian River Bay, through which the
export cable route may pass through, is relatively flat in elevation
and comprises fine to course-grained sands area.
The benthic habitat of the Project Area contains a variety of
seafloor substrates, physical features, and associated benthic
organisms. The benthic macrofaunal community of the Lease Area is
dominated by polychaetes and oligochaete worms yet may also include
sand dollars, sea stars, tube anemones, hermit crabs, rock crabs, moon
snails, nassa snails, surf clams, sea scallops, shrimp, and ocean
quahog (Guida et al., 2017).
Additional information on the underwater environment's physical
resources can be found in the COP for the Maryland Offshore Wind
Project (US Wind, 2023b) available at: <a href="https://www.boem.gov/renewable-energy/state-activities/maryland-offshore-wind">https://www.boem.gov/renewable-energy/state-activities/maryland-offshore-wind</a>-construction-and-
operations-plan.
US Wind would construct the Project in Federal and State waters
offshore of Maryland within the BOEM Lease Area OCS-A 0490 and
associated export cable routes (figure 1). The Lease Area covers
approximately 323.7 square kilometers (km\2\) (80,000 acres) and is
located approximately 18.5 km offshore of Maryland. The water depths in
the Lease Area range from 13 m along the western lease border to 41.5 m
(43 to 136.1 feet (ft)) along the southeast corner of the lease area
while depths along the export cable routes range from 10 m to 45 m (33
to 148 ft). Mean sea
[[Page 509]]
surface temperatures range from 42 to 75.8 degrees Fahrenheit ([deg]F;
5.56 to 24.3 degrees Celsius ([deg]C), while the depth-average annual
water temperature is 58.2 [deg]F (14.6 [deg]C). Cables would come
ashore at 3Rs Beach or Tower Road within Delaware Seashore State Park.
The Project Area is defined as the Lease Area and export cable route
area.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TP04JA24.000
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
Below, we provide detailed descriptions of US Wind's planned
activities, explicitly noting those that are anticipated to result in
the take of marine mammals and for which incidental take authorization
is requested. Additionally, a brief explanation is provided for those
activities that are not expected to result in the take of marine
mammals.
WTG, OSS, and Met Tower Foundations
US Wind proposes to install up to 114 WTGs on monopile foundations,
4 OSSs on 3-m pin pile jacket foundations, and one Met tower on a 1.8-m
pin pile foundation. US Wind is also considering monopile foundations
and suction bucket jacket foundations for OSSs, although 3-m pin pile
jacket foundations are the most likely foundation type. All WTG and OSS
foundations would be installed between May 1 and November 30 in 2025
(MarWin), 2026 (Momentum Wind), and 2027 (Future Development) (refer
back to table 1). No pile driving would occur December 1-April 30. For
purposes of this proposed rule, US Wind assumed all foundations would
be installed using an impact hammer, unless US Wind
[[Page 510]]
uses gravity suction bucket-based jacket foundations for OSSs.
A WTG monopile foundation typically consists of a coated single
steel tubular section, with several sections of rolled steel plate
welded together. Each monopile would have a maximum diameter of 11 m
(36 ft). WTGs would be spaced approximately 0.77 nautical miles (nmi;
1.42 km) in an east-west direction and 1.02 nmi (1.89 km) in a north-
south direction and driven to a maximum penetration depth of 50 m (164
ft) below the seafloor (US Wind, 2023a). Monopile foundations would
consist of a monopile with an integrated or separate transition piece.
US Wind would install rock scour protection around the base of the
monopile foundations prior to or following installation to minimize
scour around the foundation bases (US Wind, 2023). Monopile foundations
would be installed using an MHU 4400 impact hammer at a maximum hammer
energy of 4,400 kJ. US Wind anticipates that one monopile will be
installed per day at a rate of approximately 2 hours of active pile
driving time per monopile, though two or more monopile installations
per day may be possible depending on operational limitations and
environmental conditions (table 3).
Monopile, pin pile jacket, and gravity suction-bucket jacket
foundations are technically and economically feasible for OSSs. Up to
four OSSs would be installed via impact pile driving (monopile and pin
pile jacket foundations) or dewatering process to sink suction buckets
to the appropriate depth. Rock scour protection would be applied after
foundation installation.
Monopile foundations for the OSSs would have a maximum diameter of
11 m (36 ft) and maximum pile penetration depth of 40 m (131 ft).
Monopile foundations would have a separate transition piece with a
number of J-tubes to support and protect cables as well as to connect
the inter-array cables and the offshore export cable to the OSS. If
monopiles are selected for the OSSs, monopiles would be installed
through impact pile driving according to the same methods as described
for WTG monopile foundations.
Jacket foundations with pin piles, if selected for OSS design, may
be pre-piled or post-piled using pin piles with a maximum diameter of
3-m (9.8 ft). A pre-piled jacket would involve pin piles pre-installed
in the seabed using a template. A post-piled jacket foundation is
formed by a steel lattice construction (comprising tubular steel
members and welded joints) secured to the seabed by means of hollow
steel pin piles attached to the jacket where the pin piles have been
driven through jacket skirts (skirt piles). Each jacket structure may
have three, four, or six legs. A four-leg OSS with a post-piled pin
pile jacket foundation is the most likely design and was selected for
modeling impacts to marine mammals from OSS installation. Each jacket
foundation would consist of up to four pin piles. In total, US Wind
would install up to 4 OSSs for a total of 16 pin piles. Up to four 3-m
pin piles would be installed per day using an impact hammer with a
maximum hammer energy 1,500 kJ (table 3). Pin piles would have a
maximum diameter of 3 m (9.8 ft) each and would be installed
vertically.
US Wind plans to install one Met tower to serve as a permanent
metocean monitoring station. The Met tower foundation would be a Braced
Caisson design, in which one main steel pile would be supported
laterally by two steel supporting (bracing) piles. The main steel pin
pile would have a maximum diameter of 1.8 m (72 in) and the two bracing
pin piles would have a maximum diameter of 1.5 m (60 in). US Wind
assumed bracing pin piles would be 1.8 m in diameter for the purposes
of modeling impacts of installation on marine mammals. The main caisson
and bracing piles would be installed using an impact hammer with a
maximum energy of 500 kJ at a rate of approximately 2 hours per pin
over the course of 2 days (table 3). The Met tower would include
measurement devices to record weather conditions, such as wind and
waves, in the Project Area. US Wind identified three potential
locations for placement of the Met tower along the southern edge of the
Lease Area, as shown in figure 1-2 of the ITA application.
If US Wind installs suction bucket jacket foundations, they would
have a maximum diameter of 15 m (49 ft) and pile penetration depth of
15 m (49 ft). Suction bucket jacket foundations would be installed
through a dewatering process which generates pressure that draws the
buckets to the desired depth. The process to install a suction bucket
foundation does not produce elevated noise levels that could harass
marine mammals; therefore, no take from this activity is anticipated to
occur or is proposed to be authorized. Installation is not expected to
result in take of marine mammals. Suction bucket foundations are not
further discussed.
Table 3--Impact Pile Driving Schedule
----------------------------------------------------------------------------------------------------------------
Piling time Piling time
Project Max hammer Number of duration duration Number
Pile type component energy hammer per pile per day piles/day
(kJ) \1\ blows (min) (min)
----------------------------------------------------------------------------------------------------------------
11-m monopile................ WTG............. 1,100 600 120 120 1
2,200 2,400
3,300 \2\ 1,800
3-m pin pile jacket OSS............. 1,500 19,200 120 480 4
foundations.
1.8-m Steel Bracing Caisson Met tower....... 500 2,988 120 360 1
pile \3\.
1.8-m Steel Bracing pile \3\. 2
----------------------------------------------------------------------------------------------------------------
\1\ Assumes MHU 4400 hammer.
\2\ US Wind has proposed a hammer strike energy progression for impact pile driving of monopiles, beginning at a
hammer energy of 1,100 kJ to an energy of 3,300 kJ, although the maximum hammer energy possible (4,400 kJ) was
used and scaled in the modeling.
\3\ A bracing caisson design has one main pile supported laterally by two bracing piles. The bracing caisson
pile and bracing piles for the Met tower are pin piles.
While pre-piling preparatory work and post-piling activities could
be ongoing at one foundation position as pile driving is occurring at
another position, no concurrent/simultaneous pile driving of
foundations would occur (see Dates and Duration section). Installation
of foundations is anticipated to result in the take of marine mammals
due to noise generated during pile driving. Proposed mitigation,
monitoring, and reporting measures for impact pile driving are
described in detail later in this document (see Proposed Mitigation and
Proposed Monitoring and Reporting).
US Wind anticipates the 21 WTGs to be installed during the MarWin
campaign would become operational by December 31, 2025. The 55 WTGs to
be installed during the Momentum Wind
[[Page 511]]
campaign would become operational by December 31, 2026, and the 38 WTGs
to be installed during the Future Development campaign would become
operational by December 31, 2027 (table 2).
HRG Surveys
US Wind plans on conducting HRG surveys to identify any seabed
debris or unexploded ordnance (UXO), confirm previously surveyed site
conditions prior to cable installation, meet BOEM or other agency
requirements for additional surveys, and to refine or (microsite)
locations of construction footprints, WTG and OSS foundations, and
cables. US Wind has committed to not detonating any UXOs. US Wind would
prepare an avoidance plan for working around UXOs and conduct micro-
siting surveys to identify any UXOs in the area. Only the micro-siting
surveys have the potential to result in harassment of marine mammals
and would be limited to the Lease Area. Pre-construction and UXO HRG
surveys would utilize equipment that have operating frequencies that
are above relevant marine mammal hearing thresholds or no acoustic
output (e.g., magnetometers). Take is not anticipated from the use of
this equipment; therefore, pre-construction and UXO HRG surveys are not
analyzed further.
HRG micro-siting surveys would occur within the Lease Area,
focusing on the inter-array cable layout, as well as along the offshore
export cable corridors, if necessary. US Wind estimates approximately
14 days of HRG micro-siting survey effort per year from April through
June during years 2 and 3 (Momentum Wind in 2026, Future Development in
2027) and only during daylight hours. HRG micro-siting surveys would be
conducted using one vessel at a time. Up to 111.1 km of survey lines
would be surveyed per vessel each survey day at approximately 7.4 km/
hour (4 knots (kn)) during daylight hours. Acoustic equipment described
above (multibeam echosounders, side scan sonars, and marine
magnetometers) may be used during micro-siting surveys as well as non-
impulsive ultra-short baseline positioning equipment (i.e., Ultra-Short
BaseLine (USBL) and other parametric sub-bottom profilers), shallow
penetration sub-bottom profilers (SBPs) (e.g., Innomar SES-2000 non-
parametric SBP), and medium penetration SBPs (e.g., sparkers and
boomers). Take is not anticipated resulting from the use of ultra-short
baseline position equipment or the Innomar SBP as these equipment types
have a very narrow beam width which limits acoustic propagation, and
these sources are not analyzed further.
Of the HRG equipment types proposed for use during micro-siting
surveys, the following sources have the potential to result in take of
marine mammals:
<bullet> Medium penetration SBPs (boomers) to map deeper subsurface
stratigraphy as needed. A boomer is a broad-band sound source operating
in the 0.2 kHz to 15 kHz frequency range. This system is typically
mounted on a sled and towed behind the vessel.
<bullet> Medium penetration SBPs (sparkers) to map deeper
subsurface stratigraphy as needed. A sparker creates acoustic pulses
from 0.05 kHz to 3 kHz omni-directionally from the source that can
penetrate several hundred meters into the seafloor. These are typically
towed behind the vessel with adjacent hydrophone arrays to receive the
return signals.
Table 4 provides a list of the equipment specifications for the
medium penetration SBPs that may result in take of marine mammals
during HRG micro-siting surveys. Equipment with operating frequencies
above 180 kHz are not discussed further because they are outside the
general hearing range of marine mammals and therefore do not have the
potential to cause harassment. Although US Wind has proposed a
beamwidth of 100 degrees for the Geo Spark sparker, NMFS has determined
that a 180-degree beamwidth is more appropriate for this analysis, as
sparkers are considered omnidirectional sources (Ruppel et al., 2022).
Additionally, US Wind proposed an RMS source level of 219 decibels
(dB), based on a manufacturer specification. Because it was not clear
which operating energy, tip configuration, or specific sparker model
this source level was based on, and also because the manufacturer-
provided source levels are not well-documented, NMFS considers the
well-documented measurements for a wide variety of sparker
configurations from Crocker and Fratantonio (2016) to be the best-
available data for use in deriving appropriate proxy source levels.
Further, the RMS source levels are given directly in Crocker and
Fratantonio (2016), thus mitigating uncertainty associated with
deriving RMS levels from peak levels. For these reasons, we have
instead used an RMS source level of 206 dB, based on Crocker and
Fratantonio (2016) and a 3 dB adjustment to account for the potential
use of two 400 tip decks. Source characteristics and details of the
source proxy are found in Table 4, and its footnotes below. The net
result of NMFS's changes to the proposed methodology is an increase of
the Level B isopleth from 50.1 m to 200 m.
Proposed mitigation, monitoring, and reporting measures for HRG
micro-siting surveys are described in detail later in this document
(see Proposed Mitigation and Proposed Monitoring and Reporting).
Table 4--Summary of Representative HRG Micro-Siting Survey Equipment That May Result in Take of Marine Mammals \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Operating Peak source RMS source Pulse
HRG system Representative survey frequencies level level duration Repetition Beamwidth
equipment (kHz) (dBpeak) (dBRMS) (ms) rate (Hz) (degrees)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Medium- penetration SBP................. Applied Acoustic S Boomer 0.1-5 211 205 0.6 3 80
\2\.
AA Dura Spark 400 tip (500 0.3-4 214 206 2.3 2 180
J) \3\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
dB = decibels; Hz = hertz.
\1\ Of note, NMFS has performed a preliminary review of a report submitted by Rand (2023), that includes measurements of the Geo-Marine Geo-Source 400
sparker (400 tip, 800 J), and suggests that NMFS is assuming lower source and received levels than appropriate in its assessments of HRG impacts. NMFS
has determined that the values in our assessment remain appropriate, based on the model methodology (i.e., source level propagated using spherical
spreading) here predicting a peak level 3 dB louder than the maximum measured peak levels at the closest measurement range in Rand (2023). NMFS will
continue reviewing any available data relevant to these sources.
\2\ Crocker and Fratantonio (2016) provide Applied Acoustics S Boomer measurements. Frequency and repetition rate of the Applied Acoustics S Boomer
verified by survey contractors.
\3\ AA Dura-Spark 400 tip used as a proxy due to similar configuration and energy to the Geo-spark 2000. See Table 10 in Crocker and Fratantonio (2016)
source levels for 500 J setting and 400 tips. Based on previous survey experience, US Wind expects to operate the Geo-spark at 400-500 J per 400 tip
deck, with the possibility of one or two total 400 tip decks (i.e., 400-1000 J total energy). To account for the potential of two decks, the source
level is doubled in energy, which results in the addition of approximately 3 dB (to the 206 dB RMS, as shown in Table 4).
[[Page 512]]
Cable Landfall Construction
US Wind would bring up to four offshore export cables through
Indian River Bay to shore to landing locations at 3Rs Beach or Tower
Road within the Delaware Seashore State Park (figure 1). The US Wind
export cable would be connected to the onshore transmission cable at
the landfall locations using horizontal directional drilling (HDD) and
a jet plow. Cables would be pulled into cable ducts that would route
the cables under the beach to subterranean transition vaults, located
in existing developed areas such as parking lots. US Wind evaluated
cofferdams at the HDD locations and determined that the use of a
gravity cell would be more appropriate for soil conditions as well as
avoid the use of a vibratory hammer that would create additional
underwater sound. The gravity cell would be lowered onto the seafloor
and would not require the walls of the cell to be driven into the
seabed (i.e., no pile driving would occur). The HDD drill rig would be
set up onshore in an excavated area and the drill would advance to the
offshore exit point. The offshore cable would be pulled in through the
HDD ducts into the cable jointing/transition vault at the landfall
location. The cable installation vessel would then begin laying the
cable on the seabed as described in the Cable Laying and Installation
section below. Given the work is not expected to produce noise levels
that could result in harassment to marine mammals, HDD and gravity cell
installation is not expected to result in the take of marine mammals.
US Wind did not request, and NMFS is not proposing to authorize, take
associated with cable landfall construction; therefore, this activity
is not discussed further.
Cable Laying and Installation
Cable burial operations would occur both in the Lease Area and ECCs
from the Lease Area to shore. The inter-array cables would connect the
WTGs to any one of the OSSs. All WTGs would connect to an OSS in
strings of 4-6 WTGs via the inter-array cables. Cables within the ECCs
would carry power from the OSSs to shore at the landfall location(s)
within Delaware Seashore State Park. The offshore export cables would
be buried in the seabed at a target depth of up to 1 m (3.3 ft) to 3 m
(9.8 ft), although the exact depth would not exceed 4 m (13.1 ft).
Inter-array cable burial operations would be installed to a target
depth of 1 m (3.3 ft) to 2 m (6.6 ft), not to exceed 4 m (13.1 ft) in
depth and would follow installation of the WTG and OSS foundations as
the foundations must be in place to provide connection points. Offshore
cable installation may occur concurrently with foundation installation.
Cable laying, cable installation, and cable burial activities
planned to occur during the construction of the Project would include
the following methods: offshore export cable pull through the HDD duct,
simultaneous lay and burial for cable installation through the use of a
jet plow, and post-lay burial for cables, as needed. Offshore export
cables would be pulled through the HDD duct, as described in the Cable
Landfall Construction section above. The inter-array cables would be
installed from a dynamically positioned cable installation vessel. US
Wind plans to use a jet plow to achieve the target inter-array and
offshore cable burial depth. If necessary, post-lay cable burial would
be completed through the use of a cable installation support vessel and
remotely operated vehicle (ROV) system (US Wind, Inc., 2023a). Areas
with cable crossings or hard bottoms may require additional protection
measures, such as mattresses, rock placement, or cable protection
systems. In shallow areas of cable installation, dredging may be
necessary to allow access by the cable lay barge. As the noise levels
generated from cable laying and installation work are low, the
potential for take of marine mammals to result is discountable. US Wind
is not requesting, and NMFS is not proposing, to authorize take
associated with cable laying activities. Therefore, cable laying
activities are not analyzed further in this document.
Site Preparation and Scour Protection
Site preparation typically includes sand bedform leveling, boulder
clearance, pre-lay grapnel runs, and a pre-lay survey to prepare the
area for export cable installation. Route clearance activities would be
conducted prior to offshore export cable installation. Project
activities would include a pre-installation survey and grapnel run
along the offshore export cable corridor to remove debris that could
impact the cable lay and burial. US Wind does not expect pre-
installation seabed preparation, such as leveling, pre-trenching, to be
necessary. A pre-lay grapnel run would be conducted along the cable
route to remove debris that could impact cable lay and burial.
US Wind would also deposit rock around each foundation as scour
protection. Prior to or following the installation of a monopile or
jacket foundation for the OSS, a first layer of scour protection rocks
will be deployed in a circle around the pile location to stabilize the
seabed (US Wind, Inc., 2023a). If suction bucket foundations are
selected for OSSs, scour protection would be deployed after buckets
reach target penetration depth. A 1-2 m (2-7 ft) thick second layer of
larger rocks would be placed for stabilization once the inter-array
cables have been pulled into the monopile. Scour protection may also be
applied as additional protection for cables after burial.
NMFS does not expect scour protection placement or site preparation
work, including pre-lay grapnel runs and pre-lay surveys, to generate
noise levels that would cause take of marine mammals. Although not
anticipated, any necessary dredging, bedform leveling, or boulder
clearance would be extremely localized at any given time, and NMFS
expects that any marine mammals would not be exposed at levels or
durations likely to disrupt behavioral patterns (i.e., migrating,
foraging, calving, etc.). Therefore, the potential for the take of
marine mammals to result from these activities is so low as to be
discountable. US Wind did not request, and NMFS is not proposing, to
authorize any takes associated with site preparation and scour
protection activities; therefore, they are not analyzed further in this
document.
Vessel Operation
US Wind will utilize various types of vessels over the course of
the 5-year proposed regulations for surveying, foundation installation,
cable installation, WTG and OSS installation, and support activities.
US Wind has identified several existing port facilities located in
Maryland, Virginia, Delaware, and New Jersey to support offshore
construction, assembly and fabrication, crew transfer and logistics,
and other operational activities. In addition, some components,
materials, and vessels could come from Canadian and European ports. A
variety of vessels would be used throughout the construction
activities. These range from crew transportation vessels, tugboats,
jack-up vessels, cargo ships, and various support vessels (table 5).
Details on the vessels, related work, operational speeds, and general
trip behavior can be found in table 1-2 of the ITA application and
table 4-1 in the COP volume 1.
As part of various vessel-based construction activities, including
cable laying and construction material delivery, dynamic positioning
thrusters may be utilized to hold vessels in position or move slowly.
Sound produced through use of dynamic positioning thrusters is similar
to that
[[Page 513]]
produced by transiting vessels, and dynamic positioning thrusters are
typically operated either in a similarly predictable manner or used for
short durations around stationary activities. Fall pipe vessels may use
dynamic positioning thrusters during the installation of scour
protection up to 24 hours per day. Jack-up cranes or floating cranes
may use dynamic positioning thrusters for up to 4 hours per WTG or OSS
installation. Heavy lift and general cargo vessels may use dynamic
positioning thrusters for the delivery of Project components from the
manufacturing location to the staging/assembly port only while
maneuvering in port. Multipurpose offshore supply vessels may also use
dynamic positioning thrusters throughout the day during the pre-lay
grapnel run boulder clearance and cable burial. Jack-up or
accommodation vessels may use dynamic positioning thrusters while
constructing housing for offshore works, yet only while maneuvering to
the site, which would last approximately 2 hours per WTG or OSS.
Dynamic positioning thrusters may also be used by vessels throughout
the day for pre-installation, geophysical and geotechnical verification
surveys, cable installation, placement of scour protection and concrete
mattresses, seabed preparation and leveling, and commissioning
activities. Sound produced by dynamic positioning thrusters would be
preceded by, and associated with, sound from ongoing vessel noise and
would be similar in nature; thus, any marine mammals in the vicinity of
the activity would be aware of the vessel's presence. Construction-
related vessel activity, including the use of dynamic positioning
thrusters, is not expected to result in take of marine mammals. US Wind
did not request, and NMFS does not propose to authorize, any take
associated with vessel activity.
The total vessels expected for use during the Project are provided
in table 5; more details can be found in table 1-2 of the ITA
application. Assuming the maximum design scenario, approximately 458
total vessel round trips are expected to occur during the MarWin
construction campaign (2025), approximately 1,944 total vessel round
trips are expected to occur during the Momentum Wind construction
campaign (2026), and approximately 1,587 total vessel round trips are
expected to occur during the Future Development construction campaign
(2027). Vessels would remain on site during construction activities
each year to reduce the number of transits between the Project Area and
ports.
For operations and maintenance, US Wind anticipates that up to 10
vessels could be used, although not all vessels would operate at the
same time or every year. A fall pipe vessel, jack-up vessel, and multi-
role survey vessel only be used for non-routine maintenance activities
(table 5). Crew transfer vessels would not be likely to operate on a
daily basis year-round, however, to be conservative, US Wind assumed
that these vessels would operate on a daily basis (table 5).
Table 5--Type and Number of Vessels Anticipated During Construction and Operations
----------------------------------------------------------------------------------------------------------------
Expected
Max number of maximum
Project period Vessel types vessels annual number
of trips \1\
----------------------------------------------------------------------------------------------------------------
Foundation Installation....................... Transport, Installation, and 5 10
Support.
Crew Transfer................... 1 26
Environmental Monitoring and 4 52
Mitigation.
WTG Installation.............................. Transport, Installation, and 4 26
Support.
Crew Transfer Vessel............ 0 0
Inter-array Cable Installation................ Transport, Installation, and 4 5
Support.
Crew Transfer Vessel............ 2 136
OSS Installation.............................. Transport, Installation, and 9 16
Support.
Crew Transfer Vessel............ 0 0
Offshore Export Cable Installation............ Transport, Installation, and 6 25
Support.
Crew Transfer Vessel............ 0 0
Operations and Maintenance \2\................ Fall Pipe Vessel................ 1 1
Crew Transfer Vessel (refueling) 1 20
\3\.
Jack-up Vessel.................. 1 1
Multi-role Survey Vessel \4\.... 2 13
Sportfisher Vessel.............. 1 100
Crew Transfer Vessel............ 4 365 \5\
----------------------------------------------------------------------------------------------------------------
\1\ Vessels and trips provided represent the maximum number of year 2 trips for each vessel category for each
activity from US Wind's OCS air permit application, appendix A.
\2\ Potential operation and maintenance ports include Ocean City, MD; Baltimore, MD; and Portsmouth, VA.
\3\ Only for non-routine maintenance activities
\4\ One of these vessels would be for non-routine maintenance activities
\5\ Expected maximum annual number of trips per year for each of the four vessels. Fourth vessel may not be
necessary.
While a vessel strike could cause injury or mortality of a marine
mammal, NMFS is proposing to require extensive vessel strike avoidance
measures that would avoid vessel strikes from occurring (see Proposed
Mitigation section). US Wind has not requested, and NMFS is not
proposing to authorize, take from vessel strikes.
Fisheries and Benthic Monitoring
Fisheries and benthic monitoring surveys are being designed for the
project in collaboration with UMCES. UMCES and US Wind would conduct
pot surveys and recreational fishing surveys focusing on evaluating the
extent that commercial and recreational fisheries would be impacted due
to changes in black sea bass aggregation behaviors during and after
Project construction activities. The program includes a trial baseline
year to test deployments and collect baseline data in the Project Area
as well as a data synthesis year before construction activities would
begin. UMCES and US Wind would conduct additional passive acoustic
monitoring research for marine mammals.
[[Page 514]]
Pot surveys offshore Ocean City would be conducted monthly from
March through November using ropeless fishing gear to collect data on
black sea bass relative abundance in the vicinity of the proposed
turbine areas. Catches and sizes of other fauna would be assessed as
well. US Wind would set strings of 15 pots (six strings, up to 90 pots
total) from a commercial fishing vessel, each string with a 1-day
duration set period. EdgeTech ropeless gear (EdgeTech, 2023) would
allow sets (trawls) of 15 pots without any rope in the water column.
Approximately 300-355 m (984-1,165 ft) of \7/16\ inch (in) main-line
rope would lie on the bottom during the survey. There would also be
approximately 1.5 m of \7/16\ in line that would form the bridle
connecting each pot to the main line. Each string of pots would consist
of 15 black sea bass pots, an EdgeTech pot, and an anchor. The EdgeTech
pot would be the release pot attached at the end of each trawl. Each
survey would consist of six strings deployed for a 1-day soak time (see
diagram in Proposed Rule Comment Responses Memo, October 12, 2023).
After the 1-day set period, UMCES and US Wind would retrieve the pot
trawls by sending a release command from the on-site research vessel to
activate an acoustic release on the release pot. Upon activation, the
flotation with the attached rope would ascend to the water surface.
UMCES and US Wind would recover the floatation connected to the release
pot as well as the rest of the pots for that trawl. The pot survey
would be conducted under a NMFS Scientific LOA for black sea bass
collection research, of which a similar letter was received by UMCES
from NMFS Greater Atlantic Regional Fisheries Office (GARFO) for the
initial trial baseline year.
UMCES and US Wind would operate the recreational fishing survey off
a recreational charter vessel based in Ocean City to compare data on
black sea bass and other fauna between two artificial reef/wreck sites
and two turbine sites using a Before-After-Control-Impact (BACI) study
design. Angling techniques, such as drop bottom fishing and jigging,
would be used to collect catch data on black sea bass and other fauna.
Six monthly recreational surveys spanning a 2-day window each, would be
conducted annually from May through October.
Passive acoustic monitoring research would focus on using
rockhopper recorders to determine occurrence and position of large
whales and dolphins as well as F-POD (full waveform capture Pod)
devices to detect tonal echolocation clicks of small cetaceans in the
Lease Area. The goal of the research would be to distinguish changes in
marine mammal behavior due to natural inter-annual variation versus
behaviors influenced by wind facility operations. US Wind and UMCES
would use a before-during-after gradient design involving 2 years of
monitoring in each period before, during, and after Project
construction, from 2023 to 2029. The Rockhopper recorder would sample
at 200 kHz for baleen whales and dolphins while the F-POD would detect
echolocation clicks of small cetaceans. Rockhopper recorders would
include a localization array with the Lease Area to allow the positions
of calling North Atlantic right whales, humpback whales, and dolphins
to be detected. Innovasea receivers would also be attached at up to
four mooring sites within the Lease Area to examine spatiotemporal
patterns of previously tagged fish, such as Atlantic sturgeon, white
sharks, and sand tiger sharks.
Given the gear used (ropeless pot and hook and line), the fishery
surveys present little risk to marine mammals (although some hook and
line entanglement has been documented in marine mammals). To further
minimize this already low risk of interaction, US Wind has proposed,
and NMFS has included in the proposed rule, mitigation and monitoring
measures to avoid taking marine mammals, including, but not limited to,
monitoring for marine mammals before and during fishing/survey
activities, not deploying, pulling gear, or fishing in certain
circumstances, limiting tow times, and fully repairing nets and lines.
All vessel captains and crew would also abide by the vessel strike
avoidance measures outlined in Sec. 217.344(b) of this rule. A full
description of mitigation measures can be found in the Proposed
Mitigation section.
With the implementation of these measures, US Wind does not
anticipate, and NMFS is not proposing to authorize, take of marine
mammals incidental to research pot and recreational surveys. Given no
take is anticipated from these surveys, impacts from fishery surveys
will not be discussed further in this document (with the exception of
the description of measures in the Proposed Mitigation section).
Description of Marine Mammals in the Geographic Area
Thirty-eight marine mammal species under NMFS' jurisdiction have
geographic ranges within the western North Atlantic OCS (Hayes et al.,
2023). However, for reasons described below, US Wind has requested, and
NMFS proposes to authorize, take of only 19 species (comprising 20
stocks) of marine mammals. Sections 3 and 4 of US Wind's ITA
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 in
the application 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/draft-marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</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>).
Of the 38 marine mammal species and/or stocks with geographic
ranges that include the Project Area (i.e., found in the coastal and
offshore waters of Maryland), 19 species are not expected to be present
or are considered rare or unexpected in the Project Area based on
sighting and distribution data (see table 3-1 in US Wind's ITA
application). Specifically, the following cetacean species are known to
occur off of Maryland but are not expected to occur in the Project Area
due to the location of preferred habitat outside the Lease Area and
ECCs, based on the best available information, and therefore US Wind
did not request, and NMFS is not proposing to authorize take, of these
species: Blue whale (Balaenoptera musculus), Cuvier's beaked whale
(Ziphius cavirostris), four species of Mesoplodont beaked whales
(Mesoplodon densitostris, M. europaeus, M. mirus, and M. bidens),
Atlantic white-sided dolphin (Lagenorhynchus acutus), Clymene dolphin
(Stenella clymene), dwarf sperm whale (Kogia sima), false killer whale
(Pseudorca crassidens), Fraser's dolphin (Lagenodelphis hosei), melon-
headed whale (Peponocephala electra), northern bottlenose whale
(Hyperoodon ampullatus), pygmy killer whale (Feresa attenuata), pygmy
sperm whale (Kogia breviceps), sperm whale (Physeter macrocephalus),
spinner dolphin (Stenella longirostris), and white-beaked dolphin
(Lagenorhynchus albirostris). Two species of phocid pinnipeds are also
uncommon in the Project Area, including: harp seals (Pagophilus
groenlandica) and hooded seals (Cystophora cristata). However, harp
seals are known to strand in coastal Maryland. Therefore, NMFS is
[[Page 515]]
proposing to authorize take of harp seals.
In addition, the Florida manatee (Trichechus manatus, a sub-species
of the West Indian manatee) has been previously documented as an
occasional visitor to the Mid-Atlantic region during summer months
(Morgan et al., 2002; Cummings et al., 2014). However, manatees are
managed by the U.S. Fish and Wildlife Service (USFWS) and are not
considered further in this document.
Table 6 lists all species or stocks for which take is expected and
proposed to be authorized for this action and summarizes information
related to the population or stock, including regulatory status under
the MMPA and Endangered Species Act (ESA) and potential biological
removal (PBR), where known. PBR is defined 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'' (16 U.S.C. 1362(20)). While no
mortality is anticipated or proposed to be authorized, PBR and annual
serious injury and mortality from anthropogenic sources are included
here as gross indicators of the status of the species or stocks and
other threats. Take for 19 species (20 stocks) in table 6 is expected
and proposed to be authorized for this activity.
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 and Gulf of Mexico SARs. All values presented in
table 6 are the most recent available at the time of publication and,
unless noted otherwise, use NMFS' final 2022 SARs (Hayes et al., 2023)
available online at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>.
Table 6--Marine Mammal Species That May Occur in the Project Area and Be Taken, by Harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA status; Stock abundance (CV,
Common name \1\ Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ SI \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
North Atlantic right whale...... Eubalaena glacialis.... Western Atlantic....... E, D, Y 338 (0; 332; 2020); 0.7 \6\ 31.2
356 (346-363, 2022)
\5\.
Family Balaenopteridae (rorquals):
Fin whale....................... Balaenoptera physalus.. Western North Atlantic. E, D, Y 6,802 (0.24, 5573, 11 1.8
2016).
Sei whale....................... Balaenoptera borealis.. Nova Scotia............ E, D, Y 6,292 (1.02, 3098, 6.2 0.8
2016).
Minke whale..................... Balaenoptera Canadian Eastern -, -, N 21,968 (0.31, 17,002, 170 10.6
acutorostrata. Coastal. 2016).
Humpback whale.................. Megaptera novaeangliae. Gulf of Maine.......... -, -, Y 1,396 (0, 1,380, 2016) 22 12.15
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Killer whale \7\................ Orcinus orca........... Western North Atlantic. -, -, N UNK (UNK, UNK, 2016).. UNK 0
Long-finned pilot whale......... Globicephala melas..... Western North Atlantic. -, -, N 39,215 (0.3, 30,627, 306 29
2016).
Short-finned pilot whale........ Globicephala Western North Atlantic. -, -, Y 28,924 (0.24, 23,637, 236 136
macrorhynchus. 2016).
Bottlenose dolphin.............. Tursiops truncatus..... Western North Atlantic -, -, N 62,851 (0.23, 51,914, 519 28
Offshore. 2016).
Bottlenose dolphin.............. Tursiops truncatus..... Northern Migratory -, -, Y 6,639 (0.41, 4,759, 48 12.2-21.5
Coastal. 2016).
Common dolphin.................. Delphinus delphis...... Western North Atlantic. -, -, N 172,897 (0.21, 1,452 390
145,216, 2016).
Atlantic spotted dolphin........ Stenella frontalis..... Western North Atlantic. -, -, N 39,921 (0.27, 32,032, 320 0
2016).
Pantropical spotted dolphin..... Stenella attenuata..... Western North Atlantic. -, D, N 6,593 (0.52, 4,367, 44 0
2016).
Risso's dolphin................. Grampus griseus........ Western North Atlantic. -, -, N 35,215 (0.19, 30,051, 301 34
2016).
Rough-toothed dolphin \7\....... Steno bredanensis...... Western North Atlantic. -, -, N 136 (1, 67, 2016)..... 0.7 0
Striped dolphin \7\............. Stenella coeruleoalba.. Western North Atlantic. -, -, N 67,036 (0.29, 52,939, 529 0
2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):
Harbor porpoise................. Phocoena phocoena...... Gulf of Maine/Bay of -, -, N 95,543 (0.31, 74,034, 851 164
Fundy. 2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina......... Western North Atlantic. -, -, N 61,336 (0.08, 57,637, 1,729 339
2018).
Gray seal \8\................... Halichoerus grypus..... Western North Atlantic. -, -, N 27,300 (0.22, 22,785, 1,389 4453
2016).
Harp seal....................... Pagophilus Western North Atlantic. -, -, N 7.6M (UNK, 7.1M, 2019) 426,000 178,573
groenlandicus.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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://www.marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/">https://www.marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/</a>; Committee on Taxonomy (2022)).
[[Page 516]]
\2\ 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 2022 marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a> assessments. CV is the 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, ship strike).
\5\ The current SAR includes an estimated population (Nbest 338) based on sighting history through November 2020 (Hayes et al., 2023). In October 2023,
NMFS released a technical report identifying that the North Atlantic right whale population size based on sighting history through 2022 was 356
whales, with a 95 percent credible interval ranging from 346 to 363 (Linden, 2023).
\6\ Total annual average observed North Atlantic right whale mortality during the period 2016-2020 was 8.1 animals and annual average observed fishery
mortality was 5.7 animals. Numbers presented in this table (31.2 total mortality and 22 fishery mortality) are 2015-2019 estimated annual means,
accounting for undetected mortality and serious injury.
\7\ US Wind did not request take of these species; however, their exposure analysis demonstrates there is a low risk of harassment. Although these
species are rare in the project area, NMFS is proposing to authorize a small amount of Level B harassment in the case of potential presence during
pile driving.
\8\ NMFS' stock abundance estimate (and associated PBR value) applies to the U.S. population only. Total stock abundance (including animals in Canada)
is approximately 451,431. The annual M/SI value given is for the total stock.
As indicated above, all 19 species and 20 stocks in table 6
temporally and spatially co-occur with the activity to the degree that
take is reasonably likely to occur. Three of the marine mammal species
for which take is requested are listed as endangered under the ESA,
including North Atlantic right, fin, and sei whales. In addition to
what is included in sections 3 and 4 of US Wind's ITA application
(<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-wind-inc-construction-and-operation-maryland-offshore-wind">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-wind-inc-construction-and-operation-maryland-offshore-wind</a>), the
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 NMFS' website (<a href="https://www.fisheries.noaa.gov/species-directory/marine-mammals">https://www.fisheries.noaa.gov/species-directory/marine-mammals</a>), we provide
further detail below informing the baseline for select species (e.g.,
information regarding current UME and known important habitat areas,
such as Biologically Important Areas (BIAs; <a href="https://oceannoise.noaa.gov/biologically-important-areas">https://oceannoise.noaa.gov/biologically-important-areas</a>) (Van Parijs, 2015)).
There are no ESA-designated critical habitats for any species within
the project area (<a href="https://www.fisheries.noaa.gov/resource/map/national-esa-critical-habitat-mapper">https://www.fisheries.noaa.gov/resource/map/national-esa-critical-habitat-mapper</a>).
Under the MMPA, a UME is defined as ``a stranding that is
unexpected; involves a significant die-off of any marine mammal
population; and demands immediate response'' (16 U.S.C. 1421h(6)). As
of July 2023, five UMEs are active. Four of these UMEs are occurring
along the U.S. Atlantic coast for various marine mammal species. Of
these, the most relevant to the project area are the North Atlantic
right whale, humpback whale, and harbor and gray seal UMEs given the
prevalence of these species in the project area. More information on
UMEs, including all active, closed, or pending, can be found on NMFS'
website 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>.
Below, we include information for a subset of the species that
presently have an active or recently closed UME occurring along the
Atlantic coast or for which there is information available related to
areas of biological significance. For the majority of species
potentially present in the specific geographic region, NMFS has
designated only a single generic stock (e.g., ``western North
Atlantic'') for management purposes. This includes the ``Canadian east
coast'' stock of minke whales, which includes all minke whales found in
U.S. waters and is also a generic stock for management purposes. For
humpback and sei whales, NMFS defines stocks on the basis of feeding
locations (i.e., Gulf of Maine and Nova Scotia, respectively). However,
references to humpback whales and sei whales in this document refer to
any individuals of the species that are found in the project area. Any
areas of known biological importance (including the BIAs identified in
LaBrecque et al., 2015) that overlap spatially (or are adjacent) with
the project area are addressed in the species sections below.
North Atlantic Right Whale
The North Atlantic right whale has been listed as Endangered since
the ESA's enactment in 1973. The species was recently uplisted from
Endangered to Critically Endangered on the International Union for
Conservation of Nature (IUCN) Red List of Threatened Species (Cooke,
2020). The uplisting was due to a decrease in population size (Pace et
al., 2017), an increase in vessel strikes and entanglements in fixed
fishing gear (Daoust et al., 2017; Davis & Brillant, 2019; Knowlton et
al., 2012; Knowlton et al., 2022; Moore et al., 2021; Sharp et al.,
2019), and a decrease in birth rate (Pettis et al., 2022; Reed et al.,
2022). The western Atlantic stock is considered depleted under the MMPA
(Hayes et al., 2023). There is a recovery plan (NMFS, 2005) for the
North Atlantic right whale, and NMFS completed 5-year reviews of the
species in 2012, 2017, and 2022 which concluded no change to the
listing status is warranted.
Designated by NMFS as a Species in the Spotlight, the North
Atlantic right whale is considered among the species with the greatest
risk of extinction in the near future (<a href="https://www.fisheries.noaa.gov/topic/endangered-species-conservation/species-in-the-spotlight">https://www.fisheries.noaa.gov/topic/endangered-species-conservation/species-in-the-spotlight</a>).
The North Atlantic right whale population had only a 2.8-percent
recovery rate between 1990 and 2011 and an overall abundance decline of
23.5 percent from 2011 to 2019 (Hayes et al., 2023). Since 2011, the
North Atlantic right whale population has been in decline; however, the
sharp decrease observed from 2015 to 2020 appears to have slowed,
though the right whale population continues to experience annual
mortalities above recovery thresholds (Pace et al., 2017; Pace et al.,
2021; Linden, 2023). North Atlantic right whale calving rates dropped
from 2017 to 2020 with zero births recorded during the 2017-2018
season. The 2020-2021 calving season had the first substantial calving
increase in 5 years with 20 calves born (including 2 mortalities)
followed by 15 calves during the 2021-2022 calving season and 12 births
(including 1 mortality) in 2022-2023 calving season. These data
demonstrate that birth rates are increasing. However, mortalities
continue to outpace births. Best estimates indicate fewer than 70
reproductively active females remain in the population and adult
females experience a lower average survival rate than males (Linden,
2023). In 2023, the total annual average observed North Atlantic right
whale mortality increased from 8.1 (which represents 2016-2020) to 31.2
(which represents 2015-2019), however, this updated estimate also
accounts for undetected mortality and serious injury (Hayes et al.,
2023). Although the predicted number of deaths from the population are
lower in recent years (2021-2022) when compared to the high number of
deaths
[[Page 517]]
from 2014 to 2020 suggesting a short-term increase in survival, annual
mortality rates still exceed PBR (Linden, 2023).
Critical habitat for North Atlantic right whales is not present in
the Project Area. However, the Project Area both spatially and
temporally overlaps a portion of the migratory corridor BIA within
which North Atlantic right whales migrate south to calving grounds
generally in November and December, followed by a northward migration
(primarily moms with young calves) into feeding areas far north of the
Project Area in March and April (LaBrecque et al., 2015; Van Parijs,
2015). North Atlantic right whale foraging may rarely opportunistically
occur around the Project Area, yet the region is not considered primary
foraging habitat. Engelhaupt et al. (2023) documented feeding and
socializing behavior off Virginia and North Carolina, just south of the
Project Area, suggesting that North Atlantic right whales may use the
mid-Atlantic migratory corridor for more than just migration.
NMFS' regulations at 50 CFR 224.105 designated Seasonal Management
Areas (SMAs) for North Atlantic right whales in 2008 (73 FR 60173,
October 10, 2008). SMAs were developed to reduce the threat of
collisions between ships and North Atlantic right whales around their
migratory route and calving grounds. The Delaware Bay SMA overlaps with
the export cable corridor of the proposed project. This SMA is
currently active from November 1 through April 30 of each year and may
be used by North Atlantic right whales for migrating and/or feeding. As
noted above, NMFS is proposing changes to the North Atlantic right
whale speed rule (87 FR 46921, August 1, 2022). Due to the current
status of North Atlantic right whales and the spatial proximity overlap
of the proposed project with areas of biological significance, (i.e., a
migratory corridor, SMA), the potential impacts of the proposed project
on North Atlantic right whales warrant particular attention.
During the spring, North Atlantic right whales use the migratory
corridor BIA to move north from calving grounds off Georgia and Florida
to feeding grounds in New England and Canadian waters (Hayes et al.,
2023). Right whales feed primarily on the copepod, Calanus
finmarchicus, a species whose availability and distribution has changed
both spatially and temporally over the last decade due to an
oceanographic regime shift that has been ultimately linked to climate
change (Meyer-Gutbrod et al., 2021; Record et al., 2019; Sorochan et
al., 2019). This distribution change in prey availability has led to
shifts in right whale habitat-use patterns over the same time period
(Davis et al., 2020; Meyer-Gutbrod et al., 2022; Quintano-Rizzo et al.,
2021; O'Brien et al., 2022; Van Parijs et al., 2023) with reduced use
of foraging habitats in the Great South Channel and Bay of Fundy and
increased use of habitats within Cape Cod Bay and a region south of
Martha's Vineyard and Nantucket Islands (Stone et al., 2017; Mayo et
al., 2018; Ganley et al., 2019; Record et al., 2019; Meyer-Gutbrod et
al., 2021; Van Parijs et al., 2023); these foraging habitats are all
located several hundred kilometers north of the project area. In late
fall (i.e., November), a portion of the right whale population
(including pregnant females) typically departs the feeding grounds in
the North Atlantic, moves south along the migratory corridor BIA,
including through the Project Area, to right whale calving grounds off
Georgia and Florida. Observations of these transitions in right whale
habitat use, variability in seasonal presence in identified core
habitats, and utilization of habitat outside of previously focused
survey effort prompted the formation of a NMFS' Expert Working Group,
which identified current data collection efforts, data gaps, and
provided recommendations for future survey and research efforts (Oleson
et al., 2020). Recent research indicates understanding of their
movement patterns remains incomplete and not all of the population
undergoes a consistent annual migration (Davis et al., 2017; Gowan et
al., 2019; Krzystan et al., 2018). Non-calving females may remain in
the feeding grounds, during the winter in the years preceding and
following the birth of a calf to increase their energy stores (Gowen et
al., 2019).
Although North Atlantic right whales move seasonally between
foraging and calving grounds, Davis et al. (2017) acoustically detected
right whales along the coast from Cape Hatteras, NC, United States to
Nova Scotia, Canada year-round, suggesting that North Atlantic right
whale use of the mid-Atlantic and southeast has increased since 2010
(Davis et al., 2017). North Atlantic right whale presence in the
Project Area is predominately seasonal with individuals likely to be
transient and migrating through the area. Bailey et al. (2018)
acoustically detected the year-round presence of North Atlantic right
whales in the vicinity of the Project Area, with a maximum abundance
during the late winter and early spring. In addition, a monitoring
buoy, deployed by UMCES offshore of Ocean City Maryland in 2022,
acoustically detected the presence of North Atlantic right whales in
the lease area from November through January, with the highest
frequency of confirmed detections occurring during the months of
December and January (Woods Hole Oceanographic Institute, 2022). Visual
surveys also confirm a maximum abundance of North Atlantic right whales
in the vicinity of the Lease Area during the winter (Barco et al.,
2015; Williams et al., 2015). As part of the Mid-Atlantic Baseline
Studies Project and Maryland Project, Williams et al. (2015) conducted
standardized aerial and boat-based surveys of the Delaware, Maryland,
Virginia Wind Energy Areas (WEAs), and visually observed North Atlantic
right whales in the lease area during the months of February and March.
Based upon year-round aerial surveys conducted from 2013 to 2015, Barco
et al. (2015) observed the largest numbers of North Atlantic right
whales in the Maryland WEA during the month of January, suggesting that
the area may be a destination for non-breeding individuals and pulses
of North Atlantic right whales may travel through the region. Barco et
al. (2015) also documented North Atlantic right whale open mouth
behavior, which is consistent with, though not necessarily indicative
of, feeding. As part of the U.S. Navy's Marine Species Monitoring
Program, HDR has conducted aerial and vessel-based surveys for large
whales off Virginia and North Carolina since 2015. The majority of
North Atlantic right whale sightings have occurred in these areas, just
south of the Project Area, during the months of January-March
(Aschettino et al., 2023). The highest density month for North Atlantic
right whales in the vicinity of the lease area is February (0.00076
individuals/km (0.54 nmi grid square)) (Roberts et al., 2023).
Since 2017, 98 dead, seriously injured, or sublethally injured or
ill North Atlantic right whales along the United States and Canadian
coasts have been documented, necessitating a UME declaration and
investigation. The leading category for the cause of death for this
ongoing UME is ``human interaction,'' specifically from entanglements
or vessel strikes. As of October 30, 2023, there have been 36 confirmed
mortalities (dead, stranded, or floaters) and 34 seriously injured
free-swimming whales for a total of 70 whales. Beginning on October 14,
2022, the UME also considers animals with sublethal injury or illness
bringing the total number of whales in the UME to
[[Page 518]]
115. Approximately 42 percent of the population is known to be in
reduced health (Hamilton et al., 2021) likely contributing to smaller
body sizes at maturation, making them more susceptible to threats and
reducing fecundity (Moore et al., 2021; Reed et al., 2022; Stewart et
al., 2022). More information about the North Atlantic right whale UME
is available online at <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2023-north-atlantic-right-whale-unusual-mortality-event">https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2023-north-atlantic-right-whale-unusual-mortality-event</a>.
Humpback Whale
Humpback whales were listed as endangered under the Endangered
Species Conservation Act (ESCA) in June 1970. In 1973, the ESA replaced
the ESCA, and humpbacks continued to be listed as endangered. On
September 8, 2016, NMFS divided the once single species into 14
distinct population segments (DPS), removed the species-level listing,
and, in its place, listed four DPSs as endangered and one DPS as
threatened (81 FR 62259, September 8, 2016). The remaining nine DPSs
were not listed. The West Indies DPS, which is not listed under the
ESA, is the only DPS of humpback whales that is expected to occur in
the Project Area. Bettridge et al. (2015) estimated the size of the
West Indies DPS population at 12,312 (95 percent confidence interval
(CI) 8,688-15,954) whales in 2004-2005, which is consistent with
previous population estimates of approximately 10,000-11,000 whales
(Stevick et al., 2003; Smith et al., 1999) and the increasing trend for
the West Indies DPS (Bettridge et al., 2015).
The Project Area does not overlap with any BIAs or other important
areas for the humpback whales. A humpback whale feeding BIA extends
throughout the Gulf of Maine, Stellwagen Bank, and Great South Channel
from May through December, annually (LaBrecque et al., 2015). However,
this BIA is located approximately 556.2 km (345.6 mi) north of the
Project Area, and thus, would not be impacted by project activities.
Humpback whale presence in the mid-Atlantic varies seasonally.
Humpback whales are most typically observed in this region during the
winter months (Williams et al., 2015d; Barco et al., 2015) and are
known to be migratory off coastal Maryland, moving seasonally between
northern feeding grounds in New England and southern calving grounds in
the West Indies (Hayes et al., 2023). However, not all humpback whales
migrate to the Caribbean during the winter as individuals are sighted
in mid- to high-latitude areas during this season (Swingle et al.,
1993; Davis et al., 2020). In addition to a migratory pathway, the mid-
Atlantic region also represents a supplemental winter feeding ground
for juveniles and mature whales (Barco et al., 2002). Records of
humpback whales off the U.S. mid-Atlantic coast (New Jersey south to
North Carolina) suggest that these waters are used as a winter feeding
ground from December through March (Mallette et al., 2017; Barco et
al., 2002; LaBrecque et al., 2015) and represent important habitat for
juveniles, in particular (Swingle et al., 1993; Wiley et al., 1995).
Acoustic monitoring in the vicinity of the lease area has detected
the presence of humpback whales year-round, although detections exhibit
similar seasonal trends as visual sightings. Humpback whale detections
were lowest during the summer months (June through September),
increased through the winter (January through March) and peaked in
April (Bailey et al., 2018). Davis et al. (2020) also found detections
of humpback whales off the mid-Atlantic (Virginia) to peak from January
through May. Density modeling (Roberts et al., 2023) confirms April
(0.00187 individuals per 1 km (0.54 nmi) grid cell) as the month of the
highest average density of humpback whales in the vicinity of the
Project Area.
Since January 2016, elevated humpback whale mortalities along the
Atlantic coast from Maine to Florida led to the declaration of a UME.
As of October 2, 2023, 209 humpback whales have stranded as part of
this 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 ship strike or
entanglement. While a portion of the whales have shown evidence of pre-
mortem vessel strike, this finding is not consistent across all whales
examined and more research is needed. As the humpback whale population
has grown, they are seen more often in the mid-Atlantic. Since January
2023, 34 humpbacks have stranded along the east coast of the United
States (1 of these stranded in Maryland). These whales may have been
following their prey (small fish) which were reportedly close to shore
this past winter. These prey also attract fish that are targeted by
recreational and commercial fishermen, which increases the number of
boats in these areas. 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>.
Fin Whale
Fin whales frequently occur in the waters of the U.S. Atlantic
Exclusive Economic Zone (EEZ), principally from Cape Hatteras, North
Carolina northward and are distributed in both continental shelf and
deep-water habitats (Hayes et al., 2023). Although fin whales are
present north of the 35-degree latitude region in every season and are
broadly distributed throughout the western North Atlantic for most of
the year, densities vary seasonally (Edwards et al., 2015; Hayes et
al., 2023). Fin whales typically feed in the Gulf of Maine and the
waters surrounding New England, but their mating and calving (and
general wintering) areas are largely unknown (Hain et al., 1992; Hayes
et al., 2023). Acoustic detections of fin whale singers augment and
confirm these visual sighting conclusions for males. Recordings from
Massachusetts Bay, New York Bight, and deep-ocean areas have detected
some level of fin whale singing from September through June (Watkins et
al., 1987; Clark and Gagnon, 2002; Morano et al., 2012). These acoustic
observations from both coastal and deep-ocean regions support the
conclusion that male fin whales are broadly distributed throughout the
western North Atlantic for most of the year (Hayes et al., 2022).
Fin whale feeding BIAs occur offshore of Montauk Point, New York
from March to October (2,933 km\2\) (Hain et al., 1992; LaBrecque et
al., 2015) and year-round in the southern Gulf of Maine (18,015 km\2\).
However, given the more southerly location of the Project Area (located
approximately 364.8 km (226.7 mi) and 546.2 km (339.4 mi) away from
these BIAs, respectively), there is no spatial overlap from with these
BIAs.
Fin whales were among the most frequently observed baleen whale
species during the Maryland Wind Energy Area aerial surveys conducted
for the Maryland Department of Natural Resources (MD DNR) by the
Virginia Aquarium and Marine Science Center Foundation (Barco et al.,
2015), and the most commonly detected baleen whale species during
acoustic monitoring surveys from 2014 to 2017 in the Maryland WEA,
although the majority of detections were offshore of the WEA (Bailey et
al., 2018a). Fin whale abundance in the vicinity of the Project Area
peaked during the winter and early spring (Williams et al., 2015d;
Barco et al., 2015), with the lowest occurrence documented during
summer and early fall (Bailey et al., 2018). Consistent with visual
sightings and acoustic detections,
[[Page 519]]
the highest average density of fin whales in the vicinity of the
proposed Project Area occurs in January (0.00214 individuals per 1 km
(0.54 nmi) grid cell) (Roberts et al., 2023). There is no active fin
whale UME.
Minke Whale
Minke whales are common and widely distributed throughout the U.S.
Atlantic EEZ (Cetacean and Turtle Assessment Program (CETAP), 1982;
Hayes et al., 2022), although their distribution has a strong seasonal
component. Individuals have often been detected acoustically in shelf
waters from spring to fall and more often detected in deeper offshore
waters from winter to spring (Risch et al., 2013). Minke whales are
abundant in New England waters from May through September (Pittman et
al., 2006; Waring et al., 2014), yet largely absent from these areas
during the winter, suggesting the possible existence of a migratory
corridor (LaBrecque et al., 2015). A migratory route for minke whales
transiting between northern feeding grounds and southern breeding areas
may exist to the east of the Project Area, as minke whales may track
warmer waters along the continental shelf while migrating (Risch et
al., 2014). Risch et al. (2014) suggests the presence of a minke whale
breeding ground offshore of the southeastern US during the winter.
There are two minke whale feeding BIAs identified in the southern
and southwestern section of the Gulf of Maine, including Georges Bank,
the Great South Channel, Cape Cod Bay and Massachusetts Bay, Stellwagen
Bank, Cape Anne, and Jeffreys Ledge from March through November,
annually (LaBrecque et al., 2015). However, these BIAs are
approximately 512.1 km (318.2 mi) and 668.8 km (415.6 mi) northwest of
the Project Area, respectively, and would not be impacted by the
proposed project activities.
Overall, minke whale use of the Project Area is likely highest
during fall, winter, and spring months based upon visual sightings and
acoustic detections in the vicinity of the lease area during the months
of November, January, February, and April (Bailey et al., 2018a; Barco
et al., 2015; Williams et al., 2015b). The highest average density of
minke whales in the vicinity of the lease area is expected to occur in
May (0.00750 individuals per 1 km (0.54 nmi)).
From 2017 through 2022, elevated minke whale mortalities detected
along the Atlantic coast from Maine through South Carolina resulted in
the declaration of a UME. As of October 2, 2023, a total of 160 minke
whale mortalities have occurred during this UME. Full or partial
necropsy examinations were conducted on more than 60 percent of the
whales. Preliminary findings in several of the whales have shown
evidence of human interactions or infectious disease, but these
findings are not consistent across all of the minke whales examined, so
more research is needed. More information is available at <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2022-minke-whale-unusual-mortality-event-along-atlantic-coast">https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2022-minke-whale-unusual-mortality-event-along-atlantic-coast</a>.
Sei Whale
The Nova Scotia stock of sei whales can be found in 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). During spring and summer, the stock is
mainly concentrated in northern feeding areas, including the Scotian
Shelf (Mitchell and Chapman, 1977), the Gulf of Maine, Georges Bank,
the Northeast Channel, and south of Nantucket (CETAP, 1982; Kraus et
al., 2016; Roberts et al., 2016; Palka et al., 2017; Cholewiak et al.,
2018; Hayes et al., 2022). Sei whales have been detected acoustically
along the Atlantic Continental Shelf and Slope from south of Cape
Hatteras, North Carolina to the Davis Strait, with acoustic occurrence
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 north in June and July to feeding areas and
south in September and October to breeding areas (Mitchell, 1975;
CETAP, 1982; Davis et al., 2020). Sei whales generally occur offshore;
however, individuals may also move into shallower, more inshore waters
(Payne et al., 1990; Halpin et al., 2009; Hayes et al., 2022).
A sei whale feeding BIA occurs in New England waters from May
through November (LaBrecque et al., 2015). However, this BIA is located
approximately 501.5 km (311.6 mi) north of the Project Area and not
likely to be impacted by the Project activities.
Sei whales were sighted infrequently during visual surveys
(Williams et al., 2015d) and acoustic monitoring (WHOI, 2022; WHOI,
2023) of the Maryland WEA. The highest average density of sei whales in
the vicinity of the lease area is expected to occur during the month of
April (0.00061 individuals per 1 km (0.54 nmi) (Roberts et al., 2023).
There is no active sei whale UME.
Phocid Seals
Since June 2022, elevated numbers of harbor seal and gray seal
mortalities have occurred across the southern and central coast of
Maine. This event has been declared a UME. Preliminary testing of
samples has found some harbor and gray seals positive for highly
pathogenic avian influenza. While the UME is not occurring in the
Project Area, the populations affected by the UME are the same as those
potentially affected by the project. Information on this UME is
available online at <a href="https://www.fisheries.noaa.gov/2022-2023-pinniped-unusual-mortality-event-along-maine-coast">https://www.fisheries.noaa.gov/2022-2023-pinniped-unusual-mortality-event-along-maine-coast</a>.
The above event was preceded by a different UME, occurring from
2018 to 2020 (closure of the 2018-2020 UME 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 investigation
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 have been
conducted on some of the seals and samples have been collected for
testing. Based on tests conducted thus far, the main pathogen found in
the 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/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along">https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along</a>.
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, 2019a) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges
[[Page 520]]
(behavioral response data, anatomical modeling, etc.). Note that no
direct measurements of hearing ability have been successfully completed
for mysticetes (i.e., low-frequency cetaceans). Subsequently, NMFS
(2018) described generalized hearing ranges for these marine mammal
hearing groups. Generalized hearing ranges were chosen based on the
approximately 65-decibel (dB) threshold from the normalized composite
audiograms, with the exception for lower limits for low-frequency
cetaceans where the lower bound was deemed to be biologically
implausible and the lower bound from Southall et al. (2007) retained.
Marine mammal hearing groups and their associated hearing ranges are
provided in table 7.
Table 7--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans (dolphins, 150 Hz to 160 kHz.
toothed whales, beaked whales, bottlenose
whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus cruciger &
L. australis).
Phocid pinnipeds (PW) (underwater) (true 50 Hz to 86 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39 kHz.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65-dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al., 2007) and PW pinniped (approximation).
The pinniped functional hearing group was modified from Southall et
al. (2007) on the basis of data indicating that phocid species have
consistently demonstrated an extended frequency range of hearing
compared to otariids, especially in the higher frequency range
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt,
2013). For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
NMFS notes that in 2019a, Southall et al. recommended new names for
hearing groups that are widely recognized. However, this new hearing
group classification does not change the weighting functions or
acoustic thresholds (i.e., the weighting functions and thresholds in
Southall et al. (2019a) are identical to NMFS 2018 Revised Technical
Guidance). When NMFS updates our Technical Guidance, we will be
adopting the updated Southall et al. (2019a) hearing group
classification.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a summary and discussion of the ways that
components of the specified activity may impact marine mammals and
their habitat. The Estimated Take 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 how those impacts on individuals are
likely to impact marine mammal species or stocks. General background
information on marine mammal hearing was provided previously (see the
Description of Marine Mammals in the Geographic Area section). Here,
the potential effects of sound on marine mammals are discussed.
US Wind has requested, and NMFS proposes to authorize, the take of
marine mammals incidental to the construction activities associated
with the project area. In their application, US Wind presented their
analyses of potential impacts to marine mammals from the acoustic
sources. NMFS both carefully reviewed the information provided by US
Wind, as well as independently reviewed applicable scientific research
and literature and other information to evaluate the potential effects
of the Project's activities on marine mammals.
The proposed activities would result in the construction and
placement of up to 119 permanent foundations to support WTGs, OSSs, a
Met tower, and seafloor mapping using HRG surveys. There are a variety
of types and degrees of effects to marine mammals, prey species, and
habitat that could occur as a result of the Project. Below we provide a
brief description of the types of sound sources that would be generated
by the project, the general impacts from these types of activities, and
an analysis of the anticipated impacts on marine mammals from the
project, with consideration of the proposed mitigation measures.
Description of Sound Sources
This section contains a brief technical background on sound, on the
characteristics of certain sound types, and on metrics used in this
proposal inasmuch as the information is relevant to the specified
activity and to a discussion of the potential effects of the specified
activity on marine mammals found later in this document. For general
information on sound and its interaction with the marine environment,
please see: Au and Hastings, 2008; Richardson et al., 1995; Urick,
1983; as well as the Discovery of Sound in the Sea (DOSITS) website at
<a href="https://www.dosits.org">https://www.dosits.org</a>. Sound is a vibration that travels as an
acoustic wave through a medium such as a gas, liquid, or solid. Sound
waves alternately compress and decompress the medium as the wave
travels. These compressions and decompressions are detected as changes
in pressure by aquatic life and man-made sound receptors such as
hydrophones (underwater microphones). In water, sound waves radiate in
a manner similar to ripples on the surface of a pond and may be either
directed in a beam (narrow beam or directional sources) or sound beams
may radiate in all directions (omnidirectional sources).
Sound travels in water more efficiently than almost any other form
of energy, making the use of acoustics ideal for the aquatic
environment and its inhabitants. In seawater, sound travels at roughly
1,500 meters per second (m/s). In-air, sound waves travel much more
slowly, at about 340 m/s. However, the speed of sound can vary by a
small amount based on characteristics of the transmission
[[Page 521]]
medium, such as water temperature and salinity. Sound travels in water
more efficiently than almost any other form of energy, making the use
of acoustics ideal for the aquatic environment and its inhabitants. In
seawater, sound travels at roughly 1,500 m/s. In-air, sound waves
travel much more slowly, at about 340 m/s. However, the speed of sound
can vary by a small amount based on characteristics of the transmission
medium, such as water temperature and salinity.
The basic components of a sound wave are frequency, wavelength,
velocity, and amplitude. Frequency is the number of pressure waves that
pass by a reference point per unit of time and is measured in hertz
(Hz) or cycles per second. Wavelength is the distance between two peaks
or corresponding points of a sound wave (length of one cycle). Higher
frequency sounds have shorter wavelengths than lower frequency sounds,
and typically attenuate (decrease) more rapidly, except in certain
cases in shallower water.
The intensity (or amplitude) of sounds is measured in dB, which are
a relative unit of measurement that is used to express the ratio of one
value of a power or field to another. Decibels are measured on a
logarithmic scale, so a small change in dB corresponds to large changes
in sound pressure. For example, a 10-dB increase is a ten-fold increase
in acoustic power. A 20-dB increase is then a hundred-fold increase in
power and a 30-dB increase is a thousand-fold increase in power.
However, a ten-fold increase in acoustic power does not mean that the
sound is perceived as being 10 times louder. Decibels are a relative
unit comparing two pressures; therefore, a reference pressure must
always be indicated. For underwater sound, this is 1 microPascal
([mu]Pa). For in-air sound, the reference pressure is 20 microPascal
([mu]Pa). The amplitude of a sound can be presented in various ways;
however, NMFS typically considers three metrics. In this proposed rule,
all decibel levels are referenced to (re) 1[mu]Pa.
Sound exposure level (SEL) represents the total energy in a stated
frequency band over a stated time interval or event and considers both
amplitude and duration of exposure (represented as dB re 1 [mu]Pa\2\-
s). SEL is a cumulative metric; it can be accumulated over a single
pulse (for pile driving this is often referred to as single-strike SEL;
SEL<INF>ss</INF>) or calculated over periods containing multiple pulses
(SEL<INF>cum</INF>). Cumulative SEL represents the total energy
accumulated by a receiver over a defined time window or during an
event. The SEL metric is useful because it allows sound exposures of
different durations to be related to one another in terms of total
acoustic energy. The duration of a sound event and the number of
pulses, however, should be specified as there is no accepted standard
duration over which the summation of energy is measured.
Root mean square (rms) is the quadratic mean sound pressure over
the duration of an impulse. Root mean square is calculated by squaring
all of the sound amplitudes, averaging the squares, and then taking the
square root of the average (Urick, 1983). Root mean square accounts for
both positive and negative values; squaring the pressures makes all
values positive so that they may be accounted for in the summation of
pressure levels (Hastings and Popper, 2005). This measurement is often
used in the context of discussing behavioral effects, in part because
behavioral effects, which often result from auditory cues, may be
better expressed through averaged units than by peak pressures.
Peak sound pressure (also referred to as zero-to-peak sound
pressure or 0-pk) is the maximum instantaneous sound pressure
measurable in the water at a specified distance from the source and is
represented in the same units as the rms sound pressure. Along with
SEL, this metric is used in evaluating the potential for PTS (permanent
threshold shift) and TTS (temporary threshold shift).
Sounds can be either impulsive or non-impulsive. The distinction
between these two sound types is important because they have differing
potential to cause physical effects, particularly with regard to
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see NMFS et
al. (2018) and Southall et al. (2007, 2019a) for an in-depth discussion
of these concepts. Impulsive sound sources (e.g., airguns, explosions,
gunshots, sonic booms, impact pile driving) produce signals that are
brief (typically considered to be less than 1 second), broadband,
atonal transients (American National Standards Institute (ANSI), 1986;
ANSI, 2005; Harris, 1998; National Institute for Occupational Safety
and Health (NIOSH), 1998; International Organization for
Standardization (ISO), 2003) and occur either as isolated events or
repeated in some succession. Impulsive sounds are all characterized by
a relatively rapid rise from ambient pressure to a maximal pressure
value followed by a rapid decay period that may include a period of
diminishing, oscillating maximal and minimal pressures, and generally
have an increased capacity to induce physical injury as compared with
sounds that lack these features. Impulsive sounds are typically
intermittent in nature.
Non-impulsive sounds can be tonal, narrowband, or broadband, brief,
or prolonged, and may be either continuous or intermittent (ANSI, 1995;
NIOSH, 1998). Some of these non-impulsive sounds can be transient
signals of short duration but without the essential properties of
pulses (e.g., rapid rise time). Examples of non-impulsive sounds
include those produced by vessels, aircraft, machinery operations such
as drilling or dredging, vibratory pile driving, and active sonar
systems. Sounds are also characterized by their temporal component.
Continuous sounds are those whose sound pressure level remains above
that of the ambient sound with negligibly small fluctuations in level
(NIOSH, 1998; ANSI, 2005) while intermittent sounds are defined as
sounds with interrupted levels of low or no sound (NIOSH, 1998). NMFS
identifies Level B harassment thresholds based on if a sound is
continuous or intermittent.
Even in the absence of sound from the specified activity, the
underwater environment is typically loud due to ambient sound, which is
defined as environmental background sound levels lacking a single
source or point (Richardson et al., 1995). The sound level of a region
is defined by the total acoustical energy being generated by known and
unknown sources. These sources may include physical (e.g., wind and
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds
produced by marine mammals, fish, and invertebrates), and anthropogenic
(e.g., vessels, dredging, construction) sound. A number of sources
contribute to ambient sound, including wind and waves, which are a main
source of naturally occurring ambient sound for frequencies between 200
Hz and 50 kHz (International Council for the Exploration of the Sea
(ICES), 1995). In general, ambient sound levels tend to increase with
increasing wind speed and wave height. Precipitation can become an
important component of total sound at frequencies above 500 Hz and
possibly down to 100 Hz during quiet times. Marine mammals can
contribute significantly to ambient sound levels as can some fish and
snapping shrimp. The frequency band for biological contributions is
from approximately 12 Hz to over 100 kHz. Sources of ambient sound
related to human activity include transportation (surface vessels),
dredging and construction, oil and gas drilling and production,
geophysical surveys, sonar, and explosions. Vessel noise typically
dominates the total ambient sound for
[[Page 522]]
frequencies between 20 and 300 Hz. In general, the frequencies of
anthropogenic sounds are below 1 kHz, and if higher frequency sound
levels are created, they attenuate rapidly.
The sum of the various natural and anthropogenic sound sources that
comprise ambient sound at any given location and time depends not only
on the source levels (as determined by current weather conditions and
levels of biological and human activity) but also on the ability of
sound to propagate through the environment. In turn, sound propagation
is dependent on the spatially and temporally varying properties of the
water column and sea floor and is frequency-dependent. As a result of
the dependence on a large number of varying factors, ambient sound
levels can be expected to vary widely over both coarse and fine spatial
and temporal scales. Sound levels at a given frequency and location can
vary by 10-20 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. Human-generated sound is a significant contributor to the
acoustic environment in the project location.
Potential Effects of Underwater Sound on Marine Mammals
Anthropogenic sounds cover a broad range of frequencies and sound
levels and can have a range of highly variable impacts on marine life
from none or minor to potentially severe responses depending on
received levels, duration of exposure, behavioral context, and various
other factors. Broadly, underwater sound from active acoustic sources,
such as those in the Project, can potentially result in one or more of
the following: temporary or permanent hearing impairment, non-auditory
physical or physiological effects, behavioral disturbance, stress, and
masking (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al.,
2007; Southall et al., 2007; G[ouml]tz et al., 2009). Non-auditory
physiological effects or injuries that theoretically might occur in
marine mammals exposed to high level underwater sound or as a secondary
effect of extreme behavioral reactions (e.g., change in dive profile as
a result of an avoidance reaction) caused by exposure to sound include
neurological effects, bubble formation, resonance effects, and other
types of organ or tissue damage (Cox et al., 2006; Southall et al.,
2007; Zimmer and Tyack, 2007; Tal et al., 2015).
In general, the degree of effect of an acoustic exposure is
intrinsically related to the signal characteristics, received level,
distance from the source, and duration of the sound exposure, in
addition to the contextual factors of the receiver (e.g., behavioral
state at time of exposure, age class, etc.). In general, sudden, high-
level sounds can cause hearing loss as can longer exposures to lower-
level sounds. Moreover, any temporary or permanent loss of hearing will
occur almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur based on the activities proposed by US Wind. Richardson et al.
(1995) described zones of increasing intensity of effect that might be
expected to occur in relation to distance from a source and assuming
that the signal is within an animal's hearing range. First (at the
greatest distance) is the area within which the acoustic signal would
be audible (potentially perceived) to the animal but not strong enough
to elicit any overt behavioral or physiological response. The next zone
(closer to the receiving animal) corresponds with the area where the
signal is audible to the animal and of sufficient intensity to elicit
behavioral or physiological responsiveness. The third is a zone within
which, for signals of high intensity, the received level is sufficient
to potentially cause discomfort or tissue damage to auditory or other
systems. Overlaying these zones to a certain extent is the area within
which masking (i.e., when a sound interferes with or masks the ability
of an animal to detect a signal of interest that is above the absolute
hearing threshold) may occur; the masking zone may be highly variable
in size.
Below, we provide additional detail regarding potential impacts on
marine mammals and their habitat from noise in general, starting with
hearing impairment, as well as from the specific activities US Wind
plans to conduct, to the degree it is available (noting that there is
limited information regarding the impacts of offshore wind construction
on marine mammals).
Hearing Threshold Shift
Marine mammals exposed to high-intensity sound or to lower-
intensity sound for prolonged periods can experience hearing threshold
shift (TS), which NMFS defines 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 expressed in decibels (NMFS, 2018). Threshold shifts can be
permanent, in which case there is an irreversible increase in the
threshold of audibility at a specified frequency or portion of an
individual's hearing range or temporary, in which there is reversible
increase in the threshold of audibility at a specified frequency or
portion of an individual's hearing range and the animal's hearing
threshold would fully recover over time (Southall et al., 2019a).
Repeated sound exposure that leads to TTS could cause PTS.
When PTS occurs, there can be physical damage to the sound
receptors in the ear (i.e., tissue damage) whereas TTS represents
primarily tissue fatigue and is reversible (Henderson et al., 2008). In
addition, other investigators have suggested that TTS is within the
normal bounds of physiological variability and tolerance and does not
represent physical injury (e.g., Ward, 1997; Southall et al., 2019a).
Therefore, NMFS does not consider TTS to constitute auditory injury.
Relationships between TTS and PTS thresholds have not been studied in
marine mammals, and there is no PTS data for cetaceans. However, such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. Noise exposure can result in either a permanent
shift in hearing thresholds from baseline (a 40-dB threshold shift
approximates a PTS onset; e.g., Kryter et al., 1966; Miller, 1974;
Henderson et al., 2008) or a temporary, recoverable shift in hearing
that returns to baseline (a 6-dB threshold shift approximates a TTS
onset; e.g., Southall et al., 2019a). Based on data from terrestrial
mammals, a precautionary assumption is that the PTS thresholds,
expressed in the unweighted peak sound pressure level metric (PK), for
impulsive sounds (such as impact pile driving pulses) are at least 6 dB
higher than the TTS thresholds and the weighted PTS cumulative sound
exposure level thresholds are 15 (impulsive sound) to 20 (non-impulsive
sounds) dB higher than TTS cumulative sound exposure level thresholds
(Southall et al., 2019a). Given the higher level of sound or longer
exposure duration necessary to cause PTS as compared with TTS, PTS is
less likely to occur as a result of these activities; however, it is
possible, and a small amount has been proposed for authorization for
several species.
TTS is the mildest form of hearing impairment that can occur during
exposure to sound, with a TTS of 6 dB considered the minimum threshold
shift clearly larger than any day-to-day or session-to-session
variation in a subject's normal hearing ability (Schlundt et al., 2000;
Finneran et al., 2000; Finneran et al., 2002). While
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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. There is data on sound levels and durations necessary to
elicit mild TTS for marine mammals, but recovery is complicated to
predict and dependent on multiple factors.
Marine mammal hearing plays a critical role in communication with
conspecifics, and interpretation of environmental cues for purposes
such as predator avoidance and prey capture. Depending on the degree
(elevation of threshold in dB), duration (i.e., recovery time), and
frequency range of TTS, and the context in which it is experienced, TTS
can have effects on marine mammals ranging from discountable to serious
depending on the degree of interference of marine mammals hearing. For
example, a marine mammal may be able to readily compensate for a brief,
relatively small amount of TTS in a non-critical frequency range that
occurs during a time where ambient noise is lower and there are not as
many competing sounds present. Alternatively, a larger amount and
longer duration of TTS sustained during time when communication is
critical (e.g., for successful mother/calf interactions, consistent
detection of prey) could have more serious impacts.
Currently, TTS data only exist for four species of cetaceans
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor
porpoise, and Yangtze finless porpoise (Neophocaena asiaeorientalis))
and six species of pinnipeds (northern elephant seal (Mirounga
angustirostris), harbor seal, ring seal, spotted seal, bearded seal,
and California sea lion (Zalophus californianus)) that were exposed to
a limited number of sound sources (i.e., mostly tones and octave-band
noise with limited number of exposure to impulsive sources such as
seismic airguns or impact pile driving) in laboratory settings
(Southall et al., 2019a). There is currently no data available on
noise-induced hearing loss for mysticetes. For summaries of data on TTS
or PTS in marine mammals or for further discussion of TTS or PTS onset
thresholds, please see Southall et al. (2019a) and NMFS (2018).
Recent studies with captive odontocete species (bottlenose dolphin,
harbor porpoise, beluga, and false killer whale) have observed
increases in hearing threshold levels when individuals received a
warning sound prior to exposure to a relatively loud sound (Nachtigall
and Supin, 2013; Nachtigall and Supin, 2015; Nachtigall et al., 2016a;
Nachtigall et al., 2016b; Nachtigall et al., 2016c; Finneran, 2018;
Nachtigall et al., 2018). These studies suggest that captive animals
have a mechanism to reduce hearing sensitivity prior to impending loud
sounds. Hearing change was observed to be frequency dependent and
Finneran (2018) suggests hearing attenuation occurs within the cochlea
or auditory nerve. Based on these observations on captive odontocetes,
the authors suggest that wild animals may have a mechanism to self-
mitigate the impacts of noise exposure by dampening their hearing
during prolonged exposures of loud sound or if conditioned to
anticipate intense sounds (Finneran, 2018; Nachtigall et al., 2018).
Behavioral Effects
Exposure of marine mammals to sound sources can result in, but is
not limited to, no response or any of the following observable
responses: increased alertness; orientation or attraction to a sound
source; vocal modifications; cessation of feeding; cessation of social
interaction; alteration of movement or diving behavior; habitat
abandonment (temporary or permanent); and in severe cases, panic,
flight, stampede, or stranding, potentially resulting in death
(Southall et al., 2007). A review of marine mammal responses to
anthropogenic sound was first conducted by Richardson (1995). More
recent reviews address studies conducted since 1995 and focused on
observations where the received sound level of the exposed marine
mammal(s) was known or could be estimated (Nowacek et al., 2007;
DeRuiter et al., 2013; Ellison et al., 2012; Gomez et al., 2016). Gomez
et al. (2016) conducted a review of the literature considering the
contextual information of exposure in addition to received level and
found that higher received levels were not always associated with more
severe behavioral responses and vice versa. Southall et al. (2021)
states that results demonstrate that some individuals of different
species display clear yet varied responses, some of which have negative
implications while others appear to tolerate high levels and that
responses may not be fully predictable with simple acoustic exposure
metrics (e.g., received sound level). Rather, the authors state that
differences among species and individuals along with contextual aspects
of exposure (e.g., behavioral state) appear to affect response
probability.
Behavioral responses to sound are highly variable and context-
specific. Many different variables can influence an animal's perception
of and response to (nature and magnitude) an acoustic event. An
animal's prior experience with a sound or sound source affects whether
it is less likely (habituation) or more likely (sensitization) to
respond to certain sounds in the future (animals can also be innately
predisposed to respond to certain sounds in certain ways) (Southall et
al., 2019a). Related to the sound itself, the perceived nearness of the
sound, bearing of the sound (approaching vs. retreating), the
similarity of a sound to biologically relevant sounds in the animal's
environment (i.e., calls of predators, prey, or conspecifics), and
familiarity of the sound may affect the way an animal responds to the
sound (Southall et al., 2007; DeRuiter et al., 2013). Individuals (of
different age, gender, reproductive status, etc.) among most
populations will have variable hearing capabilities, and differing
behavioral sensitivities to sounds that will be affected by prior
conditioning, experience, and current activities of those individuals.
Often, specific acoustic features of the sound and contextual variables
(i.e., proximity, duration, or recurrence of the sound or the current
behavior that the marine mammal is engaged in or its prior experience),
as well as entirely separate factors, such as the physical presence of
a nearby vessel, may be more relevant to the animal's response than the
received level alone.
Overall, the variability of responses to acoustic stimuli depends
on the species receiving the sound, the sound source, and the social,
behavioral, or environmental contexts of exposure (e.g., DeRuiter and
Doukara, 2012). For example, Goldbogen et al. (2013a) demonstrated that
individual behavioral state was critically important in determining
response of blue whales to sonar, noting that some individuals engaged
in deep (greater than 50 m) feeding behavior had greater dive responses
than those in shallow feeding or non-feeding conditions. Some blue
whales in the Goldbogen et al. (2013a) study that were engaged in
shallow feeding behavior demonstrated no clear changes in diving or
movement even when received levels were high (~160 dB re 1[micro]Pa
(microPascal)) for exposures to 3-4 kHz sonar signals, while deep
feeding and non-feeding whales showed a clear response at exposures at
lower received levels of sonar and pseudorandom noise. Southall et al.
(2011) found that blue whales had a different response to sonar
exposure
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depending on behavioral state, more pronounced when deep feeding/travel
modes than when engaged in surface feeding.
With respect to distance influencing disturbance, DeRuiter et al.
(2013) examined behavioral responses of Cuvier's beaked whales to mid-
frequency sonar and found that whales responded strongly at low
received levels (89-127 dB re 1[micro]Pa) by ceasing normal fluking and
echolocation, swimming rapidly away, and extending both dive duration
and subsequent non-foraging intervals when the sound source was 3.4-9.5
km away. Importantly, this study also showed that whales exposed to a
similar range of received levels (78-106 dB re 1[micro]Pa) from distant
sonar exercises (118 km away) did not elicit such responses, suggesting
that context may moderate reactions. Thus, distance from the source is
an important variable in influencing the type and degree of behavioral
response and this variable is independent of the effect of received
levels (e.g., DeRuiter et al., 2013; Dunlop et al., 2017a; Dunlop et
al., 2017b; Falcone et al., 2017; Dunlop et al., 2018; Southall et al.,
2019a).
Ellison et al. (2012) outlined an approach to assessing the effects
of sound on marine mammals that incorporates contextual-based factors.
The authors recommend considering not just the received level of sound,
but also the activity the animal is engaged in at the time the sound is
received, the nature and novelty of the sound (i.e., is this a new
sound from the animal's perspective), and the distance between the
sound source and the animal. They submit that this ``exposure
context,'' as described, greatly influences the type of behavioral
response exhibited by the animal. Forney et al. (2017) also point out
that an apparent lack of response (e.g., no displacement or avoidance
of a sound source) may not necessarily mean there is no cost to the
individual or population, as some resources or habitats may be of such
high value that animals may choose to stay, even when experiencing
stress or hearing loss. Forney et al. (2017) recommend considering both
the costs of remaining in an area of noise exposure such as TTS, PTS,
or masking, which could lead to an increased risk of predation or other
threats or a decreased capability to forage, and the costs of
displacement, including potential increased risk of vessel strike,
increased risks of predation or competition for resources, or decreased
habitat suitable for foraging, resting, or socializing. This sort of
contextual information is challenging to predict with accuracy for
ongoing activities that occur over large spatial and temporal expanses.
However, distance is one contextual factor for which data exist to
quantitatively inform a take estimate, and the method for predicting
Level B harassment in this rule does consider distance to the source.
Other factors are often considered qualitatively in the analysis of the
likely consequences of sound exposure where supporting information is
available.
Behavioral change, such as disturbance manifesting in lost foraging
time, in response to anthropogenic activities is often assumed to
indicate a biologically significant effect on a population of concern.
However, individuals may be able to compensate for some types and
degrees of shifts in behavior, preserving their health and thus their
vital rates and population dynamics. For example, New et al. (2013)
developed a model simulating the complex social, spatial, behavioral,
and motivational interactions of coastal bottlenose dolphins in the
Moray Firth, Scotland, to assess the biological significance of
increased rate of behavioral disruptions caused by vessel traffic.
Despite a modeled scenario in which vessel traffic increased from 70 to
470 vessels a year (a six-fold increase in vessel traffic) in response
to the construction of a proposed offshore renewables' facility, the
dolphins' behavioral time budget, spatial distribution, motivations,
and social structure remained unchanged. Similarly, two bottlenose
dolphin populations in Australia were also modeled over 5 years against
a number of disturbances (Reed et al., 2020) and results indicate that
habitat/noise disturbance had little overall impact on population
abundances in either location, even in the most extreme impact
scenarios modeled. Friedlaender et al. (2016) provided the first
integration of direct measures of prey distribution and density
variables incorporated into across-individual analyses of behavior
responses of blue whales to sonar and demonstrated a fivefold increase
in the ability to quantify variability in blue whale diving behavior.
These results illustrate that responses evaluated without such
measurements for foraging animals may be misleading, which again
illustrates the context-dependent nature of the probability of
response.
The following subsections provide examples of behavioral responses
that give an idea of the variability in behavioral responses that would
be expected given the differential sensitivities of marine mammal
species to sound, contextual factors, and the wide range of potential
acoustic sources to which a marine mammal may be exposed. Behavioral
responses that could occur for a given sound exposure should be
determined from the literature that is available for each species, or
extrapolated from closely related species when no information exists,
along with contextual factors.
Avoidance and Displacement
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
(Eschrichtius robustus) and humpback whales are known to change
direction--deflecting from customary migratory paths--in order to avoid
noise from airgun surveys (Malme et al., 1984; Dunlop et al., 2018).
Avoidance is qualitatively different from the flight response but also
differs in the magnitude of the response (i.e., directed movement, rate
of travel, etc.). Avoidance may be short-term with animals returning to
the area once the noise has ceased (e.g., Malme et al., 1984; Bowles et
al., 1994; Goold, 1996; Stone et al., 2000; Morton and Symonds, 2002;
Gailey et al., 2007; D[auml]hne et al., 2013; Russel et al., 2016).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006; Forney et al., 2017). Avoidance of marine mammals during
the construction of offshore wind facilities (specifically, impact pile
driving) has been documented in the literature with some significant
variation in the temporal and spatial degree of avoidance and with most
studies focused on harbor porpoises as one of the most common marine
mammals in European waters (e.g., Tougaard et al., 2009; D[auml]hne et
al., 2013; Thompson et al., 2013; Russell et al., 2016; Brandt et al.,
2018).
Available information on impacts to marine mammals from pile
driving associated with offshore wind is limited to information on
harbor porpoises and seals, as the vast majority of this research has
occurred at European offshore wind projects where large whales and
other odontocete species are uncommon. Harbor porpoises and harbor
seals are considered to be behaviorally sensitive species (e.g.,
Southall et al., 2007) and the effects of wind farm construction in
Europe on
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these species have been well documented. These species have received
particular attention in European waters due to their abundance in the
North Sea (Hammond et al., 2002; Nachtsheim et al., 2021). A summary of
the literature on documented effects of wind farm construction on
harbor porpoise and harbor seals is described below.
Brandt et al. (2016) summarized the effects of the construction of
eight offshore wind projects within the German North Sea (i.e., Alpha
Ventus, BARD Offshore I, Borkum West II, DanTysk, Global Tech I,
Meerwind S[uuml]d/Ost, Nordsee Ost, and Riffgat) between 2009 and 2013
on harbor porpoises, combining passive acoustic monitoring (PAM) data
from 2010 to 2013 and aerial surveys from 2009 to 2013 with data on
noise levels associated with pile driving. Results of the analysis
revealed significant declines in porpoise detections during pile
driving when compared to 25-48 hours before pile driving began, with
the magnitude of decline during pile driving clearly decreasing with
increasing distances to the construction site. During the majority of
projects, significant declines in detections (by at least 20 percent)
were found within at least 5-10 km of the pile driving site, with
declines at up to 20-30 km of the pile driving site documented in some
cases. Similar results demonstrating the long-distance displacement of
harbor porpoises (18-25 km) and harbor seals (up to 40 km) during
impact pile driving have also been observed during the construction at
multiple other European wind farms (Tougaard et al., 2009; Bailey et
al., 2010; D[auml]hne et al., 2013; Lucke et al., 2012; Haelters et
al., 2015).
While harbor porpoises and seals tend to move several kilometers
away from wind farm construction activities, the duration of
displacement has been documented to be relatively temporary. In two
studies at Horns Rev II using impact pile driving, harbor porpoise
returned within 1 to 2 days following cessation of pile driving
(Tougaard et al., 2009; Brandt et al., 2011). Similar recovery periods
have been noted for harbor seals off England during the construction of
four wind farms (Brasseur et al., 2012; Carroll et al., 2010; Hamre et
al., 2011; Hastie et al., 2015; Russell et al., 2016). In some cases,
an increase in harbor porpoise activity has been documented inside wind
farm areas following construction (e.g., Lindeboom et al., 2011). Other
studies have noted longer term impacts after impact pile driving. Near
Dogger Bank in Germany, harbor porpoises continued to avoid the area
for over 2 years after construction began (Gilles et al., 2009).
Approximately 10 years after construction of the Nysted wind farm,
harbor porpoise abundance had not recovered to the original levels
previously seen, although the echolocation activity was noted to have
been increasing when compared to the previous monitoring period
(Teilmann and Carstensen, 2012). However, overall, there are no
indications for a population decline of harbor porpoises in European
waters (e.g., Brandt et al., 2016). Notably, where significant
differences in displacement and return rates have been identified for
these species, the occurrence of secondary project-specific influences
such as use of mitigation measures (e.g., bubble curtains, acoustic
deterrent devices (ADDs)), or the manner in which species use the
habitat in the project area, are likely the driving factors of this
variation.
NMFS notes the aforementioned studies from Europe involve
installing much smaller piles than US Wind proposes to install and,
therefore, we anticipate noise levels from impact pile driving to be
louder. For this reason, we anticipate that the greater distances of
displacement observed in harbor porpoise and harbor seals documented in
Europe are likely to occur off Maryland. However, we do not anticipate
any greater severity of response due to harbor porpoise and harbor seal
habitat use off Maryland or population-level consequences similar to
European findings. In many cases, harbor porpoises and harbor seals are
resident to the areas where European wind farms have been constructed.
However, off Maryland, harbor porpoises are transient (with higher
abundances in winter when foundation installation would not occur) and
a very small percentage of the large harbor seal population are only
seasonally present with no rookeries established. In summary, we
anticipate that harbor porpoise and harbor seals will likely respond to
pile driving by moving several kilometers away from the source but
return to typical habitat use patterns when pile driving ceases.
Some avoidance behavior of other marine mammal species has been
documented to be dependent on distance from the source. As described
above, DeRuiter et al. (2013) noted that distance from a sound source
may moderate marine mammal reactions in their study of Cuvier's beaked
whales (an acoustically sensitive species), which showed the whales
swimming rapidly and silently away when a sonar signal was 3.4-9.5 km
away while showing no such reaction to the same signal when the signal
was 118 km away even though the received levels were similar. Tyack et
al. (1983) conducted playback studies of Surveillance Towed Array
Sensor System (SURTASS) low-frequency active (LFA) sonar in a gray
whale migratory corridor off California. Similar to North Atlantic
right whales, gray whales migrate close to shore (approximately +2 km)
and are low-frequency hearing specialists. The LFA sonar source was
placed within the gray whale migratory corridor (approximately 2 km
offshore) and offshore of most, but not all, migrating whales
(approximately 4 km offshore). These locations influenced received
levels and distance to the source. For the inshore playbacks, not
unexpectedly, the louder the source level of the playback (i.e., the
louder the received level), whale avoided the source at greater
distances. Specifically, when the source level was 170 dB rms and 178
dB rms, whales avoided the inshore source at ranges of several hundred
meters, similar to avoidance responses reported by Malme et al. (1983,
1984). Whales exposed to source levels of 185 dB rms demonstrated
avoidance levels at ranges of +1 km. Responses to the offshore source
broadcasting at source levels of 185 and 200 dB, avoidance responses
were greatly reduced. While there was observed deflection from course,
in no case did a whale abandon its migratory behavior.
The signal context of the noise exposure has been shown to play an
important role in avoidance responses. In a 2007-2008 Bahamas study,
playback sounds of a potential predator--a killer whale--resulted in a
similar but more pronounced reaction in beaked whales (an acoustically
sensitive species), which included longer inter-dive intervals and a
sustained straight-line departure of more than 20 km from the area
(Boyd et al., 2008; Southall et al., 2009; Tyack et al., 2011). US Wind
does not anticipate, and NMFS is not proposing to authorize take of
beaked whales and, moreover, the sounds produced by US Wind do not have
signal characteristics similar to predators. Therefore, we would not
expect such extreme reactions to occur. Southall et al. (2011) found
that blue whales had a different response to sonar exposure depending
on behavioral state, more pronounced when deep feeding/travel modes
than when engaged in surface feeding.
One potential consequence of behavioral avoidance is the altered
energetic expenditure of marine mammals because energy is required to
move and avoid surface vessels or the
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sound field associated with active sonar (Frid and Dill, 2002). Most
animals can avoid that energetic cost by swimming away at slow speeds
or speeds that minimize the cost of transport (Miksis-Olds, 2006), as
has been demonstrated in Florida manatees (Miksis-Olds, 2006). Those
energetic costs increase, however, when animals shift from a resting
state, which is designed to conserve an animal's energy, to an active
state that consumes energy the animal would have conserved had it not
been disturbed. Marine mammals that have been disturbed by
anthropogenic noise and vessel approaches are commonly reported to
shift from resting to active behavioral states, which would imply that
they incur an energy cost.
Forney et al. (2017) detailed the potential effects of noise on
marine mammal populations with high site fidelity, including
displacement and auditory masking, noting that a lack of observed
response does not imply absence of fitness costs and that apparent
tolerance of disturbance may have population-level impacts that are
less obvious and difficult to document. Avoidance of overlap between
disturbing noise and areas and/or times of particular importance for
sensitive species may be critical to avoiding population-level impacts
because (particularly for animals with high site fidelity) there may be
a strong motivation to remain in the area despite negative impacts.
Forney et al. (2017) stated that, for these animals, remaining in a
disturbed area may reflect a lack of alternatives rather than a lack of
effects.
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, but observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996; Frid and Dill, 2002). 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, beaked
whale strandings (Cox et al., 2006; D'Amico et al., 2009). 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.
Flight responses of marine mammals have been documented in response to
mobile high intensity active sonar (e.g., Tyack et al., 2011; DeRuiter
et al., 2013; Wensveen et al., 2019), and more severe responses have
been documented when sources are moving towards an animal or when they
are surprised by unpredictable exposures (Watkins, 1986; Falcone et
al., 2017). Generally speaking, however, marine mammals would be
expected to be less likely to respond with a flight response to either
stationery pile driving (which they can sense is stationery and
predictable) or significantly lower-level HRG surveys, unless they are
within the area ensonified above behavioral harassment thresholds at
the moment the source is turned on (Watkins, 1986; Falcone et al.,
2017).
Diving and Foraging
Changes in dive behavior in response to noise exposure can vary
widely. They 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;
Goldbogen et al., 2013b). Variations in dive behavior may reflect
interruptions in biologically significant activities (e.g., foraging)
or they may be of little biological significance. Variations in dive
behavior may also expose an animal to potentially harmful conditions
(e.g., increasing the chance of ship-strike) or may serve as an
avoidance response that enhances survivorship. The impact of a
variation in diving resulting from an acoustic exposure depends on what
the animal is doing at the time of the exposure, the type and magnitude
of the response, and the context within which the response occurs
(e.g., the surrounding environmental and anthropogenic circumstances).
Nowacek et al. (2004) reported disruptions of dive behaviors in
foraging North Atlantic right whales when exposed to an alerting
stimulus, an action, they noted, that could lead to an increased
likelihood of ship strike. The alerting stimulus was in the form of an
18-minute exposure that included three 2-minute signals played three
times sequentially. This stimulus was designed with the purpose of
providing signals distinct to background noise that serve as
localization cues. However, the whales did not respond to playbacks of
either right whale social sounds or vessel noise, highlighting the
importance of the sound characteristics in producing a behavioral
reaction. Although source levels for the proposed pile driving
activities may exceed the received level of the alerting stimulus
described by Nowacek et al. (2004), proposed mitigation strategies
(further described in the Proposed Mitigation section) will reduce the
severity of response to proposed pile driving activities. Converse to
the behavior of North Atlantic right whales, Indo-Pacific humpback
dolphins have been observed to dive for longer periods of time in areas
where vessels were present and/or approaching (Ng and Leung, 2003). In
both of these studies, the influence of the sound exposure cannot be
decoupled from the physical presence of a surface vessel, thus
complicating interpretations of the relative contribution of each
stimulus to the response. Indeed, the presence of surface vessels,
their approach, and speed of approach, seemed to be significant factors
in the response of the Indo-Pacific humpback dolphins (Ng and Leung,
2003). Low-frequency signals of the Acoustic Thermometry of Ocean
Climate (ATOC) sound source were not found to affect dive times of
humpback whales in Hawaiian waters (Frankel and Clark, 2000) or to
overtly affect elephant seal dives (Costa et al., 2003). They did,
however, produce subtle effects that varied in direction and degree
among the individual seals, illustrating the equivocal nature of
behavioral effects and consequent difficulty in defining and predicting
them.
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 cessation of secondary
indicators of foraging (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; Southall et al., 2019b). An understanding 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 can facilitate the assessment of whether
foraging disruptions are likely to incur fitness consequences
(Goldbogen et al., 2013b; Farmer et al., 2018; Pirotta et al., 2018a;
Southall et al., 2019a; Pirotta et al., 2021).
Impacts on marine mammal foraging rates from noise exposure have
been documented, though there is little data regarding the impacts of
offshore turbine construction specifically. Several broader examples
follow, and it
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is reasonable to expect that exposure to noise produced during the 5
years that the proposed rule would be effective could have similar
impacts. Visual tracking, passive acoustic monitoring, and movement
recording tags were used to quantify sperm whale behavior prior to,
during, and following exposure to airgun arrays at received levels in
the range 140-160 dB at distances of 7-13 km, following a phase-in of
sound intensity and full array exposures at 1-13 km (Madsen et al.,
2006; Miller et al., 2009). Sperm whales did not exhibit horizontal
avoidance behavior at the surface. However, foraging behavior may have
been affected. The sperm whales exhibited 19 percent less vocal (buzz)
rate during full exposure relative to post exposure, and the whale that
was approached most closely had an extended resting period and did not
resume foraging until the airguns had ceased firing. The remaining
whales continued to execute foraging dives throughout exposure;
however, swimming movements during foraging dives were 6 percent lower
during exposure than during control periods (Miller et al., 2009).
Miller et al. (2009) noted that more data are required to understand
whether the differences were due to exposure or natural variation in
sperm whale behavior. Balaenopterid whales exposed to moderate low-
frequency signals similar to the ATOC sound source demonstrated no
variation in foraging activity (Croll et al., 2001), whereas five out
of six North Atlantic right whales exposed to an acoustic alarm
interrupted their foraging dives (Nowacek et al., 2004). Although the
received SPLs were similar in the latter two studies, the frequency,
duration, and temporal pattern of signal presentation were different.
These factors, as well as differences in species sensitivity, are
likely contributing factors to the differential response. The source
levels of both the proposed construction and HRG activities exceed the
source levels of the signals described by Nowacek et al. (2004) and
Croll et al. (2001), and noise generated by US Wind's activities at
least partially overlap in frequency with the described signals. Blue
whales exposed to mid-frequency sonar in the Southern California Bight
were less likely to produce low-frequency calls usually associated with
feeding behavior (Melc[oacute]n et al., 2012). However, Melc[oacute]n
et al. (2012) were unable to determine if suppression of low-frequency
calls reflected a change in their feeding performance or abandonment of
foraging behavior and indicated that implications of the documented
responses are unknown. Further, it is not known whether the lower rates
of calling actually indicated a reduction in feeding behavior or social
contact since the study used data from remotely deployed, passive
acoustic monitoring buoys. Results from the 2010-2011 field season of a
behavioral response study in Southern California waters indicated that,
in some cases and at low received levels, tagged blue whales responded
to mid-frequency sonar but that those responses were mild and there was
a quick return to their baseline activity (Southall et al., 2011;
Southall et al., 2012b; Southall et al., 2019).
Information on or estimates of the energetic requirements of the
individuals and the relationship between prey availability, foraging
effort and success, and the life history stage of the animal will help
better inform a determination of whether foraging disruptions incur
fitness consequences. Foraging strategies may impact foraging
efficiency, such as by reducing foraging effort and increasing success
in prey detection and capture, in turn promoting fitness and allowing
individuals to better compensate for foraging disruptions. Surface
feeding blue whales did not show a change in behavior in response to
mid-frequency simulated and real sonar sources with received levels
between 90 and 179 dB re 1 [micro]Pa, but deep feeding and non-feeding
whales showed temporary reactions including cessation of feeding,
reduced initiation of deep foraging dives, generalized avoidance
responses, and changes to dive behavior (DeRuiter et al., 2017;
Goldbogen et al., 2013b; Sivle et al., 2015). Goldbogen et al. (2013b)
indicate that disruption of feeding and displacement could impact
individual fitness and health. However, for this to be true, we would
have to assume that an individual whale could not compensate for this
lost feeding opportunity by either immediately feeding at another
location, by feeding shortly after cessation of acoustic exposure, or
by feeding at a later time. There is no indication that individual
fitness and health would be impacted, particularly since unconsumed
prey would likely still be available in the environment in most cases
following the cessation of acoustic exposure.
Similarly, while the rates of foraging lunges decrease in humpback
whales due to sonar exposure, there was variability in the response
across individuals, with one animal ceasing to forage completely and
another animal starting to forage during the exposure (Sivle et al.,
2016). In addition, almost half of the animals that demonstrated
avoidance were foraging before the exposure, but the others were not;
the animals that avoided while not feeding responded at a slightly
lower received level and greater distance than those that were feeding
(Wensveen et al., 2017). These findings indicate the behavioral state
of the animal and foraging strategies play a role in the type and
severity of a behavioral response. For example, when the prey field was
mapped and used as a covariate in examining how behavioral state of
blue whales is influenced by mid-frequency sound, the response in blue
whale deep-feeding behavior was even more apparent, reinforcing the
need for contextual variables to be included when assessing behavioral
responses (Friedlaender et al., 2016).
Vocalizations and Auditory Masking
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, production of echolocation clicks, calling,
and singing. Changes in vocalization behavior in response to
anthropogenic noise can occur for any of these modes and may result
directly from increased vigilance or a startle response, or from a need
to compete with an increase in background noise (see Erbe et al., 2016
review on communication masking), the latter of which is described more
below.
For example, in the presence of potentially masking signals,
humpback whales and killer whales have been observed to increase the
length of their songs (Miller et al., 2000; Fristrup et al., 2003;
Foote et al., 2004) and blue whales increased song production (Di Iorio
and Clark, 2009), while North Atlantic right whales have been observed
to shift the frequency content of their calls upward while reducing the
rate of calling in areas of increased anthropogenic noise (Parks et
al., 2007). In some cases, animals may cease or reduce sound production
during production of aversive signals (Bowles et al., 1994; Thode et
al., 2020; Cerchio et al., 2014; McDonald et al., 1995). Blackwell et
al. (2015) showed that whales increased calling rates as soon as airgun
signals were detectable before ultimately decreasing calling rates at
higher received levels.
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, or
navigation) (Richardson et al., 1995; Erbe and Farmer, 2000; Tyack,
2000; Erbe et al., 2016). Masking occurs when the receipt of a sound is
interfered with
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by another coincident sound at similar frequencies and at similar or
higher intensity and may occur whether the sound is natural (e.g.,
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g.,
shipping, sonar, seismic exploration) in origin. The ability of a noise
source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age, or TTS hearing loss),
and existing ambient noise and propagation conditions.
Masking these acoustic signals can disturb the behavior of
individual animals, groups of animals, or entire populations. Masking
can lead to behavioral changes including vocal changes (e.g., Lombard
effect, increasing amplitude, or changing frequency), cessation of
foraging or lost foraging opportunities, and leaving an area, to both
signalers and receivers, in an attempt to compensate for noise levels
(Erbe et al., 2016) or because sounds that would typically have
triggered a behavior were not detected. In humans, significant masking
of tonal signals occurs as a result of exposure to noise in a narrow
band of similar frequencies. As the sound level increases, the
detection of frequencies above those of the masking stimulus decreases.
This principle is expected to apply to marine mammals as well because
of common biomechanical cochlear properties across taxa.
Therefore, when the coincident (masking) sound is man-made, it may
be considered harassment when disrupting behavioral patterns. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which only occurs during the sound exposure.
Because masking (without resulting in threshold shift) is not
associated with abnormal physiological function, it is not considered a
physiological effect, but rather a potential behavioral effect.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009; Matthews, 2017) and may result in energetic or
other costs as animals change their vocalization behavior (e.g., Miller
et al., 2000; Foote et al., 2004; Parks et al., 2007; Di Iorio and
Clark, 2009; Holt et al., 2009). Masking can be reduced in situations
where the signal and noise come from different directions (Richardson
et al., 1995), through amplitude modulation of the signal, or through
other compensatory behaviors (Houser and Moore, 2014). Masking can be
tested directly in captive species (e.g., Erbe, 2008), but in wild
populations it must be either modeled or inferred from evidence of
masking compensation. There are few studies addressing real-world
masking sounds likely to be experienced by marine mammals in the wild
(e.g., Branstetter et al., 2013; Cholewiak et al., 2018).
The echolocation calls of toothed whales are subject to masking by
high-frequency sound. Human data indicate low-frequency sound can mask
high-frequency sounds (i.e., upward masking). Studies on captive
odontocetes by Au et al. (1974, 1985, 1993) indicate that some species
may use various processes to reduce masking effects (e.g., adjustments
in echolocation call intensity or frequency as a function of background
noise conditions). There is also evidence that the directional hearing
abilities of odontocetes are useful in reducing masking at the high-
frequencies these cetaceans use to echolocate, but not at the low-to-
moderate frequencies they use to communicate (Zaitseva et al., 1980). A
study by Nachtigall and Supin (2008) showed that false killer whales
adjust their hearing to compensate for ambient sounds and the intensity
of returning echolocation signals.
Impacts on signal detection, measured by masked detection
thresholds, are not the only important factors to address when
considering the potential effects of masking. As marine mammals use
sound to recognize conspecifics, prey, predators, or other biologically
significant sources (Branstetter et al., 2016), it is also important to
understand the impacts of masked recognition thresholds (often called
``informational masking''). Branstetter et al. (2016) measured masked
recognition thresholds for whistle-like sounds of bottlenose dolphins
and observed that they are approximately 4 dB above detection
thresholds (energetic masking) for the same signals. Reduced ability to
recognize a conspecific call or the acoustic signature of a predator
could have severe negative impacts. Branstetter et al. (2016) observed
that if ``quality communication'' is set at 90 percent recognition the
output of communication space models (which are based on 50 percent
detection) would likely result in a significant decrease in
communication range.
As marine mammals use sound to recognize predators (Allen et al.,
2014; Cummings and Thompson, 1971; Cur[eacute] et al., 2015; Fish and
Vania, 1971), the presence of masking noise may also prevent marine
mammals from responding to acoustic cues produced by their predators,
particularly if it occurs in the same frequency band. For example,
harbor seals that reside in the coastal waters off British Columbia are
frequently targeted by mammal-eating killer whales. The seals
acoustically discriminate between the calls of mammal-eating and fish-
eating killer whales (Deecke et al., 2002), a capability that should
increase survivorship while reducing the energy required to attend to
all killer whale calls. Similarly, sperm whales (Cur[eacute] et al.,
2016; Isojunno et al., 2016), long-finned pilot whales (Visser et al.,
2016), and humpback whales (Cur[eacute] et al., 2015) changed their
behavior in response to killer whale vocalization playbacks; these
findings indicate that some recognition of predator cues could be
missed if the killer whale vocalizations were masked. The potential
effects of masked predator acoustic cues depend on the duration of the
masking noise and the likelihood of a marine mammal encountering a
predator during the time that detection and recognition of predator
cues are impeded.
Redundancy and context can also facilitate detection of weak
signals. These phenomena may help marine mammals detect weak sounds in
the presence of natural or manmade noise. Most masking studies in
marine mammals present the test signal and the masking noise from the
same direction. The dominant background noise may be highly directional
if it comes from a particular anthropogenic source such as a ship or
industrial site. Directional hearing may significantly reduce the
masking effects of these sounds by improving the effective signal-to-
noise ratio.
Masking affects both senders and receivers of acoustic signals and,
at higher levels and longer duration, can potentially have long-term
chronic effects on marine mammals at the population level as well as at
the individual level. Low-frequency ambient sound levels have increased
by as much as 20 dB (more than three times
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in terms of sound pressure level (SPL)) in the world's ocean from pre-
industrial periods, with most of the increase from distant commercial
shipping (Hildebrand, 2009; Cholewiak et al., 2018). All anthropogenic
sound sources, but especially chronic and lower-frequency signals
(e.g., from commercial vessel traffic), contribute to elevated ambient
sound levels, thus intensifying masking.
In addition to making it more difficult for animals to perceive and
recognize acoustic cues in their environment, anthropogenic sound
presents separate challenges for animals that are vocalizing. When they
vocalize, animals are aware of environmental conditions that affect the
``active space'' (or communication space) of their vocalizations, which
is the maximum area within which their vocalizations can be detected
before it drops to the level of ambient noise (Brenowitz, 2004; Brumm
et al., 2004; Lohr et al., 2003). Animals are also aware of
environmental conditions that affect whether listeners can discriminate
and recognize their vocalizations from other sounds, which is more
important than simply detecting that a vocalization is occurring
(Brenowitz, 1982; Brumm et al., 2004; Dooling, 2004; Marten and Marler,
1977; Patricelli and Blickley, 2006). Most species that vocalize have
evolved with an ability to adjust their vocalizations to increase the
signal-to-noise ratio, active space, and recognizability/
distinguishability of their vocalizations in the face of temporary
changes in background noise (Brumm et al., 2004; Patricelli and
Blickley, 2006). Vocalizing animals can adjust their vocalization
characteristics such as the frequency structure, amplitude, temporal
structure, and temporal delivery (repetition rate), or ceasing to
vocalize.
Many animals will combine several of these strategies to compensate
for high levels of background noise. Anthropogenic sounds that reduce
the signal-to-noise ratio of animal vocalizations, increase the masked
auditory thresholds of animals listening for such vocalizations, or
reduce the active space of an animal's vocalizations impair
communication between animals. Most animals that vocalize have evolved
strategies to compensate for the effects of short-term or temporary
increases in background or ambient noise on their songs or calls.
Although the fitness consequences of these vocal adjustments are not
directly known in all instances, like most other trade-offs animals
must make, some of these strategies likely come at a cost (Patricelli
and Blickley, 2006; Noren et al., 2017; Noren et al., 2020). Shifting
songs and calls to higher frequencies may also impose energetic costs
(Lambrechts, 1996).
Marine mammals are also known to make vocal changes in response to
anthropogenic noise. In cetaceans, vocalization changes have been
reported from exposure to anthropogenic noise sources such as sonar,
vessel noise, and seismic surveying (e.g., Gordon et al., 2003; Di
Iorio and Clark, 2009; Hatch et al., 2012; Holt et al., 2009; Holt et
al., 2011; Lesage et al., 1999; McDonald et al., 2009; Parks et al.,
2007; Risch et al., 2012; Rolland et al., 2012), as well as changes in
the natural acoustic environment (Dunlop et al., 2014). Vocal changes
can be temporary or can be persistent. For example, model simulation
suggests that the increase in starting frequency for the North Atlantic
right whale upcall over the last 50 years resulted in increased
detection ranges between right whales. The frequency shift, coupled
with an increase in call intensity by 20 dB, led to a call
detectability range of less than 3 km to over 9 km (Tennessen and
Parks, 2016). Holt et al. (2009) measured killer whale call source
levels and background noise levels in the 1 to 40 kHz band and reported
that the whales increased their call source levels by 1-dB SPL for
every 1-dB SPL increase in background noise level. Similarly, another
study on St. Lawrence River belugas reported a similar rate of increase
in vocalization activity in response to passing vessels (Scheifele et
al., 2005). Di Iorio and Clark (2009) showed that blue whale calling
rates vary in association with seismic sparker survey activity, with
whales calling more on days with surveys than on days without surveys.
They suggested that the whales called more during seismic survey
periods as a way to compensate for the elevated noise conditions.
In some cases, these vocal changes may have fitness consequences,
such as an increase in metabolic rates and oxygen consumption, as
observed in bottlenose dolphins when increasing their call amplitude
(Holt et al., 2015). A switch from vocal communication to physical,
surface-generated sounds such as pectoral fin slapping or breaching was
observed for humpback whales in the presence of increasing natural
background noise levels, indicating that adaptations to masking may
also move beyond vocal modifications (Dunlop et al., 2010).
While these changes all represent possible tactics by the sound-
producing animal to reduce the impact of masking, the receiving animal
can also reduce masking by using active listening strategies such as
orienting to the sound source, moving to a quieter location, or
reducing self-noise from hydrodynamic flow by remaining still. The
temporal structure of noise (e.g., amplitude modulation) may also
provide a considerable release from masking through comodulation
masking release (a reduction of masking that occurs when broadband
noise, with a frequency spectrum wider than an animal's auditory filter
bandwidth at the frequency of interest, is amplitude modulated)
(Branstetter and Finneran, 2008; Branstetter et al., 2013). Signal type
(e.g., whistles, burst-pulse, sonar clicks) and spectral
characteristics (e.g., frequency modulated with harmonics) may further
influence masked detection thresholds (Branstetter et al., 2016;
Cunningham et al., 2014).
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources, such as vessels. Several studies
have shown decreases in marine mammal communication space and changes
in behavior as a result of the presence of vessel noise. For example,
right whales were 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) as well as increasing the
amplitude (intensity) of their calls (Parks, 2009; Parks et al., 2011).
Clark et al. (2009) observed that right whales' communication space
decreased by up to 84 percent in the presence of vessels. Cholewiak et
al. (2018) also observed loss in communication space in Stellwagen
National Marine Sanctuary for North Atlantic right whales, fin whales,
and humpback whales with increased ambient noise and shipping noise.
Although humpback whales off Australia did not change the frequency or
duration of their vocalizations in the presence of ship noise, their
source levels were lower than expected based on source level changes to
wind noise, potentially indicating some signal masking (Dunlop, 2016).
Multiple delphinid species have also been shown to increase the minimum
or maximum frequencies of their whistles in the presence of
anthropogenic noise and reduced communication space (e.g., Holt et al.,
2009; Holt et al., 2011; Gervaise et al., 2012; Williams et al., 2013;
Hermannsen et al., 2014; Papale et al., 2015; Liu et al., 2017). While
masking impacts are not a concern from lower intensity, higher
frequency HRG surveys, some degree of masking would be expected in the
vicinity of turbine pile driving and concentrated support vessel
operation. However, pile driving
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is an intermittent sound and would not be continuous throughout the
day.
Habituation and Sensitization
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to sti
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