Potential Impacts of Offshore Wind on the Marine Ecosystem and Associated Species: Background and Issues for Congress

Potential Impacts of Offshore Wind on the Marine Ecosystem and Associated Species: Background and Issues for Congress

Potential Impacts of Offshore Wind on the
January 5, 2024
Marine Ecosystem and Associated Species:
Caitlin Keating-Bitonti,
Background and Issues for Congress
Coordinator
Analyst in Natural
Offshore wind energy is one alternative to energy derived from the combustion of fossil fuels.
Resources Policy
The United States’ ability to harness wind energy from the outer continental shelf (OCS) is at an

initial stage compared with European countries and some Asian countries. As interest in the
Anthony R. Marshak
potential benefits of offshore wind grows in the United States, some stakeholders have expressed
Analyst in Natural
concerns about offshore wind projects’ potential impacts on the marine ecosystem.
Resources Policy

Offshore wind projects may affect the marine ecosystem and associated species in ways both
adverse and beneficial. Stakeholders commonly cite effects such as changes to the ocean
Laura B. Comay
environment; habitat alterations; risks that living marine resources may collide with construction
Specialist in Natural
vessels and offshore wind structures; altered behaviors and disturbance of migration paths of
Resources Policy
certain fish, marine mammals, and birds; and water pollution. Some observers emphasize that,

although individual offshore wind energy projects may have local, immediate impacts to certain
Corrie E. Clark
species, the global ocean and the wildlife it supports are threatened by the long-term
Specialist in Energy Policy
consequences of climate change. Many scientists concur that renewable power is important for

addressing climate change and reducing its longer term environmental impacts. Some
Erin H. Ward
stakeholders have encouraged decisionmakers to include climate change risks facing the ocean
Coordinator of Research
and certain marine animals in analyses of offshore wind projects.
Planning

The National Environmental Policy Act (NEPA; 42 U.S.C. §§4321 et seq.) requires federal
agencies to evaluate the impacts of major federal actions significantly affecting the human
Pervaze A. Sheikh
environment, such as issuing permits for offshore wind projects on the U.S. OCS. The
Specialist in Natural
Department of the Interior’s (DOI’s) Bureau of Ocean Energy Management (BOEM) is the lead
Resources Policy
agency for the preparation of environmental impact statements (EISs) in the context of approving

developers’ construction and operations plans for offshore wind energy projects. BOEM’s
responsibilities also include coordinating interagency review and permitting timelines in

accordance with provisions of the Fixing America’s Surface Transportation Act (42 U.S.C.
§§4370m–4370m12). Certain federal agencies have further been tasked with administering specific statutes that aim to
protect particular aspects of the environment or certain natural resources. The National Oceanic and Atmospheric
Administration’s National Marine Fisheries Service (NMFS) cooperates in the EIS processes pursuant to its responsibilities
under the Endangered Species Act (ESA; 16 U.S.C. §§1531-1544) and the Marine Mammal Protection Act (16 U.S.C.
§§1361-1423h). DOI’s U.S. Fish and Wildlife Service considers the ESA and the Migratory Bird Treaty Act of 1918 (16
U.S.C. §703) when participating in EIS processes. Other agencies may also have responsibilities related to permitting and
environmental review of offshore wind projects.
The U.S. Department of Energy lists 59 offshore wind projects in federal and state waters at various stages of development,
ranging from conception to construction to fully commissioned. In federal waters, DOI BOEM has issued more than 30
leases for offshore wind development (some covering multiple projects) and anticipates completing review of at least 16
construction and operations plans by 2025. Several projects are currently operating in state and federal waters in the Atlantic
region. Two commercial-scale projects in federal waters off Massachusetts and Rhode Island—Vineyard Wind 1 and South
Fork Wind—have begun delivering power. A two-turbine pilot project operated by Dominion Energy is generating electricity
in waters off Virginia. The five-turbine Block Island project is operating in state waters off Rhode Island.
In the 118th Congress, some Members called for additional research into the potential harm offshore wind projects may cause
to marine wildlife or expressed concern about the impacts that offshore wind activities might have on other ocean uses (e.g.,
H.R. 1). The full impacts of offshore wind activities on the U.S. OCS remain unclear, in part because the development of
U.S. offshore wind projects is relatively recent. Issues for Congress may include potential impacts of offshore wind
development on the marine ecosystem and potential long-term benefits of climate change mitigation derived from offshore
renewable energy versus the immediate, local impacts of offshore wind to the marine ecosystem and associated species.
Other concerns may include the potential loss of fishing grounds, interruption to NMFS surveys, incidental take (or
unintentional killing) of birds, and increased vessel activity that may be associated with offshore wind projects.
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Contents
Introduction ..................................................................................................................................... 1
U.S. Offshore Wind Energy in a Global Context ............................................................................ 2
U.S. Policies .............................................................................................................................. 3
Background on Offshore Wind Energy Project Development ......................................................... 3
Offshore Wind Energy Turbine Structures ................................................................................ 4
Selected Activities Associated with Offshore Wind Projects .................................................... 6
Potential Impacts of Offshore Wind Energy on the Marine Ecosystem and Associated
Species .......................................................................................................................................... 8
Ocean Environment ................................................................................................................... 9
Marine Mammals ..................................................................................................................... 11
Whales .............................................................................................................................. 14
Marine Invertebrates ............................................................................................................... 16
Fishes ...................................................................................................................................... 18
Fisheries ............................................................................................................................ 20
Sea Turtles ............................................................................................................................... 21
Birds ........................................................................................................................................ 22
Bats .......................................................................................................................................... 25
Relevant Statutes for Federal Agency Actions Related to Offshore Wind Projects ...................... 26
National Environmental Policy Act ......................................................................................... 26
Fixing America’s Surface Transportation Act ......................................................................... 28
Marine Mammal Protection Act .............................................................................................. 29
Endangered Species Act .......................................................................................................... 30
Migratory Bird Treaty Act ....................................................................................................... 32
Issues for Congress ........................................................................................................................ 33
Research on the Impacts of Offshore Wind Energy Development and Mitigation
Strategies .............................................................................................................................. 33
Offshore Wind Development and Competing Ocean Uses ..................................................... 35

Figures
Figure 1. Offshore Wind Turbine Components and Foundation Structures .................................... 5
Figure 2. Examples of Floating Wind Mooring Systems .............................................................. 13
Figure 3. Schematic of Artificial Reef on Offshore Wind Foundation .......................................... 17

Tables
Table 1. Potential Impacts Associated with Offshore Wind Energy Projects .................................. 9
Table 2. Selected Bird Species That May Be Impacted by Offshore Wind Projects ..................... 25

Contacts
Author Information ........................................................................................................................ 39
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Potential Impacts of Offshore Wind on Marine Ecosystems and Species

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Introduction
Development of renewable energy, such as offshore wind energy, is one approach to reducing
anthropogenic carbon dioxide (CO2) emissions by providing alternatives to the combustion of
fossil fuels. Many scientists concur that renewable power is important for addressing climate
change and reducing its longer term environmental impacts (see text box “Effects of Climate
Change on the Ocean”).1 As interest in the potential benefits of harnessing offshore wind for
energy grows in the United States, some stakeholders have expressed concerns about the impacts
that offshore wind energy development may have on the marine ecosystem and associated
species. Environmental impact statements (EISs) for proposed offshore wind projects have found
a range of impacts—both adverse and beneficial—on various resources; these impacts are mostly
projected to be minor to moderate, while in some cases they are negligible or major.2
As the federal government pursues policies for the development of offshore wind energy projects
on the U.S. outer continental shelf (OCS),3 Congress may continue to deliberate actions to
mitigate the potential effects of offshore wind energy projects (across several developmental
stages) on the marine ecosystem and associated species. For example, the James M. Inhofe
National Defense Authorization Act for Fiscal Year 2023 (Division J, Title CXIII, Subtitle C,
§11319, of P.L. 117-263) directed a study of the impacts on certain marine living resources from
the development of renewable energy on the West Coast. In the 118th Congress, House-passed
legislation would direct the Government Accountability Office (GAO) to “assess the sufficiency
of the environmental review processes for offshore wind projects,” including offshore wind
impacts on finfish, invertebrates, whales, and other marine mammals.4
This report discusses various aspects of how offshore wind projects may impact the marine
ecosystem and associated species. First, the report discusses impacts that may be associated with
different offshore wind project activities (e.g., site assessment and construction). Second, the
report discusses how offshore wind projects may alter the local ocean environment and the ways
in which certain species may be directly or indirectly impacted by offshore wind projects. The
report in part draws on observational studies of ecological impacts surrounding offshore wind
farms (OWFs) in the North Sea, since this area of the world provides the longest record of
modern OWFs (see “U.S. Offshore Wind Energy in a Global Context,” below). Other potential
species impacts are informed by observational studies of land-based wind farms (e.g., collision
risk to birds) or laboratory studies mimicking conditions (e.g., noise levels) often associated with
offshore wind construction or operation. Third, the report discusses the responsibilities of federal
agencies under various laws to consider and potentially mitigate these impacts. The broader role

1 Intergovernmental Panel on Climate Change, “Summary for Policymakers,” in Climate Change 2023: Synthesis
Report, eds. Core Writing Team, Hoesung Lee, and José Romero, 2023, p. 21.
2 For example, see Bureau of Ocean Energy Management (BOEM), “Vineyard Wind 1 Offshore Wind Energy Project
Final Environmental Impact Statement Volume 1,” March 2021, pp. ES-13-ES-14, https://www.boem.gov/sites/default/
files/documents/renewable-energy/state-activities/Vineyard-Wind-1-FEIS-Volume-1.pdf. Environmental impact
statements (EISs) are discussed in greater detail in the “Relevant Statutes for Federal Agency Actions Related to
Offshore Wind Projects” section of this report.
3 The U.S. outer continental shelf (OCS) is the seabed and subsoil beneath the U.S.-exclusive economic zone located
generally between 3 and 200 nautical miles from the shoreline. White House, “Proclamation 5030: Exclusive Economic
Zone of the United States of America,” 48 Federal Register 10605, March 10, 1983.
4 Division B, Title 1, §20119, of H.R. 1. In June 2023, Rep. Chris Smith announced that the U.S. Government
Accountability Office (GAO) had agreed to undertake such a study in response to Member requests (Rep. Chris Smith,
“GAO Agrees to Smith’s Request for Independent Investigation into the Impacts of New Jersey’s Unprecedented
Offshore Wind Industrialization,” press release, June 15, 2023, https://chrissmith.house.gov/news/
documentsingle.aspx?DocumentID=411511).
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of federal agencies in the development of offshore wind (beyond environmental review) is
outside the scope of this report.5 Finally, the report discusses some issues for possible
congressional consideration, such as additional research on potential impacts associated with
offshore wind on the U.S. OCS and competing ocean uses.
U.S. Offshore Wind Energy in a Global Context
Compared with some European and Asian countries, the United States’ deployment of offshore
wind energy on the U.S. OCS is at an initial stage.6 Some countries began exploring the
development and deployment of modern OWFs as early as the 1990s, when Denmark, the United
Kingdom, Sweden, and the Netherlands built OWFs as demonstration projects in the North Sea.7
In 2022, Europe accounted for 51.0% of global offshore wind capacity, followed by Asia
(48.9%).8 China’s offshore wind experienced substantial growth in 2021 and 2022; by the end of
2022, China accounted for nearly 44% of the world’s offshore wind capacity.9
According to the Department of Energy, the United States has 59 offshore wind projects in
federal and state waters at various stages of development, ranging from conception to
construction to fully commissioned.10 In federal waters, the Department of the Interior’s (DOI’s)
Bureau of Ocean Energy Management (BOEM) has issued more than 30 leases for offshore wind
development (some covering multiple projects) and anticipates completing review of at least 16
construction and operations plans (COPs) by 2025.11 Several projects are currently operating in
state and federal waters in the Atlantic region.12

5 For information about the role of federal agencies in the development of offshore renewable energy, see CRS Report
R46970, U.S. Offshore Wind Energy Development: Overview and Issues for the 118th Congress, by Laura B. Comay
and Corrie E. Clark; CRS Report R40175, Offshore Wind Energy Development: Legal Framework, by Adam Vann.
6 Department of Energy (DOE), “Grand Challenges to Close the Gaps in Offshore Wind Energy Research,” October
2022, https://www.energy.gov/eere/wind/articles/grand-challenges-close-gaps-offshore-wind-energy-research.
7 Ørsted, “Making Green Energy Affordable,” June 2019, https://orsted.com/-/media/WWW/Docs/Corp/COM/explore/
Making-green-energy-affordable-June-2019.pdf.
8 North America makes up the remaining offshore wind capacity at 0.1%. DOE, Offshore Wind Market Report: 2023
Edition, DOE/GO-102023-6059, August 2023, p. 53 (hereinafter cited as DOE, 2023 Market Report).
9 Ibid.
10 Ibid., p. 15. For most coastal states, state-controlled waters extend to three nautical miles off the coast. For more
information, see CRS Report R40175, Offshore Wind Energy Development: Legal Framework, by Adam
Vann, Offshore Wind Energy Development: Legal Framework, by Adam Vann; and CRS Report RL33404, Offshore
Oil and Gas Development: Legal Framework, by Adam Vann, Offshore Oil and Gas Development: Legal Framework,
by Adam Vann. Offshore wind projects also have been considered for the Great Lakes under state jurisdiction.
11 BOEM, Budget Justifications and Performance Information, Fiscal Year 2024, p. 25, https://www.boem.gov/sites/
default/files/documents/about-boem/budget/FY-2024-BOEM-Congressional-Justification_0.pdf. BOEM’s approval of
a construction and operations plan (COP), along with needed permits from other agencies, allows a lessee to initiate
project construction and operations. For more information about U.S. offshore wind energy development, see CRS
Report R46970, U.S. Offshore Wind Energy Development: Overview and Issues for the 118th Congress, by Laura B.
Comay and Corrie E. Clark.
12 As of the date of this CRS report, two commercial-scale projects in federal waters off Massachusetts and Rhode
Island—Vineyard Wind 1 and South Fork Wind—had begun delivering power. Additionally, a two-turbine pilot project
operated by Dominion Energy is generating electricity in waters off Virginia. The five-turbine Block Island project is
operating in state waters off Rhode Island. For more information, see CRS Report R46970, U.S. Offshore Wind Energy
Development: Overview and Issues for the 118th Congress, by Laura B. Comay and Corrie E. Clark.
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U.S. Policies
Several executive branch and congressional actions have set the stage for increased development
and deployment of offshore wind energy on the U.S. OCS.13 For example, Section 388 of the
Energy Policy Act of 2005 (P.L. 109-58) amended the Outer Continental Shelf Lands Act (43
U.S.C. §§1331-1356c) to authorize the Secretary of the Interior to offer leases, easements, and
rights-of-way for offshore renewable energy activities on the U.S. OCS.14 BOEM is the lead
agency for the U.S. OCS renewable energy leasing program.15 In the 117th Congress, Section
50251 of the Inflation Reduction Act of 2022 (P.L. 117-196) expanded BOEM’s authority to
pursue offshore wind leasing in federal waters in the southeastern Atlantic region, in the eastern
Gulf of Mexico, and off U.S. territories.16
On the executive side, the Biden Administration suggested a doubling of offshore wind by 2030
as one potential approach to address climate change in Executive Order (E.O.) 14008, “Tackling
the Climate Crisis at Home and Abroad.”17 In March 2021, the Biden Administration announced a
government-wide effort to deploy 30 gigawatts (or 30,000 megawatts) of offshore wind energy by
2030.18 In September 2022, the Administration announced a related goal to deploy 15 gigawatts
(or 15,000 megawatts) of installed floating offshore wind platforms (i.e., structures that are not
set into the ocean floor) by 2035.19 As of December 2023, BOEM has conducted 12 competitive
wind energy lease sales for areas on the OCS, representing more than 2.5 million acres of
commercial wind energy lease areas offshore of Delaware, Louisiana, Maryland, Massachusetts,
New Jersey, New York, North Carolina, Rhode Island, South Carolina, Virginia, and California.20
Background on Offshore Wind Energy Project
Development
Stakeholders have expressed concerns regarding potential impacts to the marine ecosystem and
associated species that pertain to offshore wind project activities associated with site
development, construction, operation, and decommissioning.21 The following sections provide

13 For more information, see CRS Report R46970, U.S. Offshore Wind Energy Development: Overview and Issues for
the 118th Congress, by Laura B. Comay and Corrie E. Clark; and CRS Report R40175, Offshore Wind Energy
Development: Legal Framework, by Adam Vann.
14 P.L. 109-58, §388 (43 U.S.C. §1337(p)), authorized the Secretary of the Interior to issue leases, easements, and
rights-of-way for energy development “from sources other than oil and gas.”
15 BOEM, “Renewable Energy of the Outer Continental Shelf,” https://www.boem.gov/renewable-energy/renewable-
energy-program-overview.
16 For more information, see CRS Insight IN11980, Offshore Wind Provisions in the Inflation Reduction Act, by Laura
B. Comay, Corrie E. Clark, and Molly F. Sherlock.
17 Executive Order (E.O.) 14008, “Tackling the Climate Crisis at Home and Abroad,” 86 Federal Register 7619,
January 27, 2021.
18 White House, “Biden Administration Jumpstarts Offshore Wind Energy Projects to Create Jobs,” fact sheet, March
29, 2021, https://www.whitehouse.gov/briefing-room/statements-releases/2021/03/29/fact-sheet-biden-administration-
jumpstarts-offshore-wind-energy-projects-to-create-jobs/.
19 White House, “Biden-⁠Harris Administration Announces New Actions to Expand U.S. Offshore Wind Energy,” fact
sheet, September 15, 2022, https://www.whitehouse.gov/briefing-room/statements-releases/2022/09/15/fact-sheet-
biden-harris-administration-announces-new-actions-to-expand-u-s-offshore-wind-energy/.
20 BOEM, FY2024 Budget Justifications and Performance Information, p. 31.
21 For example, John Harwood et al., “Understanding the Population Consequences of Acoustic Disturbance for Marine
Mammals,” in The Effects of Noise on Aquatic Life II, eds. Arthur N. Popper and Anthony Hawkins (New York:
(continued...)
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background on offshore wind energy turbine structures and discuss activities associated with
offshore wind projects, including the potential impacts of these activities on the marine ecosystem
and species.
Offshore Wind Energy Turbine Structures
OWFs are constructed in bodies of water and use wind to generate electricity in much the same
manner as land-based wind farms do. OWFs can be made up of a few to hundreds of turbine
structures that are spaced apart to optimize power generation and can require large, open bodies
of water.22 In general, OWFs generate more electricity per turbine structure than land-based wind
farms because offshore wind towers and blades are typically taller and larger than land-based
wind structures.23 Local conditions such as wind speed, meteorological patterns, and terrain can
influence the quality of a wind resource; typically wind speeds are stronger and more consistent
offshore than onshore.24 Figure 1 depicts the typical components of an offshore wind turbine
structure.

Springer Verlag, 2016), pp. 417-423 (hereinafter referred to as Harwood et al., “Acoustic Disturbance for Marine
Mammals”); and see H.Res. 239 in the 118th Congress.
22 DOE, National Renewable Energy Laboratory, “Offshore Wind Energy Facility Characteristics,” March 5, 2018,
slides 12, 13, and 15, https://www.boem.gov/sites/default/files/renewable-energy-program/What-Does-an-Offshore-
Wind-Energy-Facility-Look-Like.pdf.
23 DOE, “Wind Turbines: The Bigger, the Better,” https://www.energy.gov/eere/articles/wind-turbines-bigger-better.
24 National Grid, “Onshore vs Offshore Wind Energy: What’s the Difference?,” at https://www.nationalgrid.com/
stories/energy-explained/onshore-vs-offshore-wind-energy.
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Figure 1. Offshore Wind Turbine Components and Foundation Structures

Source: Bureau of Safety and Environmental Enforcement, “Renewable Energy Policy Statement,”
https://web.archive.org/web/20200728214215/https:/www.bsee.gov/what-we-do/renewable-energy/renewable-
energy-policy-statement.
Notes: Rotating blades capture and convert wind energy into mechanical energy. Nacelle contains the electric
generator and equipment to convert the mechanical energy to electrical energy. Turbine support tower supports
the mass of the other three wind turbine system elements. For fixed foundations, transition pieces provide
connections between the foundation and the wind turbine tower and can serve as an access platform for
workers; foundations secure the wind turbine towers to the seafloor. For floating technologies, platforms can
provide access for workers; hulls are the watertight body of floating vessels. Undersea cables transmitting
electric power from turbines to shore are not shown.
There are two types of offshore wind energy turbine structures: fixed-foundation towers and
floating structures. Fixed-bottom foundation support structures are the predominant offshore wind
technology, largely because fixed-bottom foundations are well suited for offshore conditions in
Europe, where the industry first developed (Figure 1).25 Foundations secure the tower with the
other components to the seafloor. There are several types of foundation technologies, the most
common of which is the monopile.26 Fixed-bottom foundations may not be appropriate for all

25 National Offshore Wind Research and Development Consortium, Research and Development Roadmap Version 2.0,
October 2019, p. 6.
26 Monopiles, which accounted for approximately 64% of the global operating offshore wind capacity in 2021, are
cylindrical structures driven or drilled into the seafloor and attached to the bottom of the turbine tower. Other
foundation technologies include jackets and gravity-based foundations. Jacket structures typically consist of four legs
that are connected by braces and attached via anchors or drilled piles into the seafloor. Gravity-based foundations are
placed on the seafloor and rely on the structure’s weight to resist overturning. DOE, 2022 Market Report, p. 67.
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U.S. offshore sites because of differences such as the profile of the continental shelf, water depth,
seabed characteristics, and extreme weather conditions.
The offshore wind industry is beginning to use floating structures, which are not set into the
ocean floor (Figure 1).27 These floating structures are affixed to the seabed through cables or legs
rather than supported by a foundation. Floating structures are often used for projects sited in deep
water (approximately 60 meters, or 200 feet, in depth or deeper), such as areas in the Gulf of
Maine and off the Pacific Coast and Hawaii.28 Most planned floating projects use
semisubmersible structures.29 Figure 1 depicts several types of fixed-bottom and floating
structures.
The rotating blades of the wind turbine capture and convert wind energy into mechanical energy.
The nacelle sits at the top of the offshore wind turbine structure, and it contains the electric
generator and other equipment to convert the mechanical energy to electrical energy.30 The
electricity produced by offshore wind turbines typically travels to an onshore substation through
undersea power transmission cables.31 In addition to the onshore substation, some OWFs also
may have offshore platform substations.32
Different components of the offshore wind structure may affect certain marine species in different
ways or not at all. For example, foundations may pose a collision risk for disoriented large fish or
marine mammals, or foundations may serve as a new habitat for certain marine invertebrates
(e.g., mussels). These possibilities and others are discussed in greater detail in “Potential Impacts
of Offshore Wind Energy on the Marine Ecosystem and Associated Species,” below.
Selected Activities Associated with Offshore Wind Projects
The life span of an offshore wind project can be characterized by four broad phases: planning and
analysis, leasing, site assessment, and construction and operations.33 With respect to impacts on
marine ecosystems and wildlife, stakeholders may particularly consider the effects of certain
activities associated with the site assessment and the construction and operations phases. In
general, activities related to offshore wind site assessment include environmental planning and
site design (including site characterization studies), evaluation of wind potential, technology

27 BOEM’s December 2022 lease sale for the Pacific region included areas expected to be developed with floating wind
projects. According to DOI, “the lease sale included a 20-percent credit for bidders who committed to a monetary
contribution to programs or initiatives that support workforce training programs for the floating offshore wind industry,
the development of a U.S. domestic supply chain for the floating offshore wind energy industry, or both. This credit
will result in over $117 million in investments for these critical programs or initiatives.” DOI, “Biden-Harris
Administration Announces Winners of California Offshore Wind Energy Auction,” press release, December 7, 2022,
https://doi.gov/pressreleases/biden-harris-administration-announces-winners-california-offshore-wind-energy-auction.
28 DOE, 2023 Market Report, p. 54.
29 Ibid., p. 69. Other floating structure designs can include barges, tension leg platforms, and spar technologies.
30 DOE, “How a Wind Turbine Works – Text Version,” https://www.energy.gov/eere/wind/how-wind-turbine-works-
text-version.
31 For information about undersea cables and relevant U.S. policies, see CRS Report R47648, Protection of Undersea
Telecommunication Cables: Issues for Congress, coordinated by Jill C. Gallagher and Nicole T. Carter.
32 Pamela Middleton and Bethany Barnhart, Supporting National Environmental Policy Act Documentation for
Offshore Wind Energy Development Related to Heat from Buried Transmission Cables, U.S. Department of the
Interior, Bureau of Ocean Energy Management, OCS Study BOEM 2023-006, Washington, DC, January 2023, pp. 2-3,
https://www.boem.gov/sites/default/files/documents/renewable-energy/studies/
Transmission_Cable_Heat_WhitePaper.pdf.
33 See, for example, BOEM, “Wind Energy Commercial Leasing Process,” fact sheet, May 2021,
https://www.boem.gov/sites/default/files/documents/about-boem/Wind-Energy-Comm-Leasing-Process-FS-
01242017Text-052121Branding.pdf.
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review, and component selection.34 Construction activities include the installation of offshore
substations and wind turbine structures, as well as their connection to the electrical grid (i.e.,
laying of undersea power transmission cables), which may take 7 to 11 years to complete.35
During operation, turbine blades (which collect wind energy to generate electricity that is
transmitted to the electrical grid) and other structural components may require maintenance,
repair, and rehabilitation. In addition to focusing on the broad phases characterized by BOEM,
some stakeholders also consider potential impacts from the decommissioning phase, which marks
the end of an offshore wind turbine’s useful life and the dismantling or repurposing of the existing
infrastructure. The typical life span of an offshore wind turbine is about 20 to 25 years, although a
number of factors could shorten or extend the useful life.36
The risks that offshore wind projects pose to the marine ecosystem and associated species vary
depending on the project phase and associated activities. Activities associated with site
assessment and construction of offshore wind projects may pose greater risks to marine wildlife
than when the OWF is in operation, for example, whereas rotating turbine blades during operation
may pose the greatest risks to birds and bats. Other examples include the following:
• During a site assessment, a lessee uses geological and geophysical (G&G)
surveys to identify sites for offshore renewable energy structures, among other
purposes.37 G&G surveys use sound waves that are reflected off seafloor
structures to collect data on conditions at and beneath the seafloor.38 The noise
generated from these surveys may cause injury, hearing loss, or behavior
changes, among other impacts, to certain marine species.39
• During construction, increased numbers of construction vessels may transit
between the shore and the offshore project site.40 Heightened vessel activity may
increase collision risks for some marine species (e.g., whales). Construction also
entails driving piles as anchor points to support the foundations of wind
turbines.41 Pile-driving creates high levels of underwater noise as well as sound
pressure that travels through the water column; the noise and pressure can impact
certain marine species, both in the construction area and up to tens of kilometers
away.42

34 Iberdrola, “Construction of an Offshore Wind Plant,” https://www.iberdrola.com/about-us/our-activity/offshore-
wind-energy/offshore-wind-park-construction (hereinafter referred to as Iberdrola, Construction of OWF).
35 Ibid.
36 A. M. Jadali et al., “Decommissioning vs. repowering of offshore wind farms—a techno-economic assessment,”
International Journal of Advanced Manufacturing Technology, vol. 112, (2021), pp. 2519–2532.
37 BOEM, “Geological and Geophysical (G&G) Surveys,” fact sheet, November 2018, https://www.boem.gov/sites/
default/files/about-boem/BOEM-Regions/Atlantic-Region/GandG-Overview.pdf (hereinafter referred to as BOEM,
G&G Fact Sheet).
38 Ibid.
39 BOEM, “The Science Behind the Decision,” https://www.boem.gov/sites/default/files/about-boem/BOEM-Regions/
Atlantic-Region/FAQ-Atlantic-GandG-Activities.pdf.
40 American Clean Power, “Offshore Wind Vessel Needs,” https://cleanpower.org/wp-content/uploads/2021/09/
Offshore-Wind-Vessel-Needs.FINAL_.2021.pdf.
41 Iberdrola, Construction of OWF.
42 One kilometer is approximately 0.621 miles (or 0.54 nautical miles). Frank Thomsen et al., Effects of Offshore Wind
Farm Noise on Marine Mammals and Fish, COWRIE, Ltd., Hamburg, Germany, 2006 (hereinafter referred to as
Thomsen et al., Effects of Offshore Wind Farm Noise); P. T. Madsen et al., “Wind Turbine Underwater Noise and
Marine Mammals: Implications of Current Knowledge and Data Needs,” Marine Ecology Progress Series, vol. 309
(2006), pp. 279-295 (hereinafter referred to as Madsen et al., “Wind Turbine Underwater Noise”); Anita Gilles et al.,
(continued...)
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• During operation, rotating turbine blades may alter the ocean environment in the
immediate area of the OWF and may produce underwater noise that may impact
some marine species. In addition, turbine blades pose a collision risk for birds
and bats.
• During the decommissioning of an offshore wind project, the equipment and
components of the offshore wind infrastructure may be reused, recycled, or
disposed of. The potential impacts associated with these activities remain largely
unknown, since many offshore wind turbines have yet to reach the end of their
useful lives.
Federal permits and approvals require that project developers take mitigation steps that have the
potential to reduce impacts associated with many of these activities.
Potential Impacts of Offshore Wind Energy on the
Marine Ecosystem and Associated Species
Offshore wind projects may affect the marine ecosystem and associated species. Not all impacts
may be adverse; some may be beneficial (e.g., the artificial reef effect, discussed below). In
general, OWF activities can impact wildlife through
• atmospheric and oceanic change,43
• marine habitat alteration,
• collision risk,
• electromagnetic field (EMF) effects associated with power cables,44
• noise effects, and
• water quality (e.g., pollution).45
The scientific literature analyzes the short-term adverse impacts and benefits of offshore wind
development to marine mammals, invertebrates, fish, sea turtles, birds, bats, and other
components of the marine ecosystem (Table 1).46 Modeling and observational studies (mostly

“Seasonal Distribution of Harbour Porpoises and Possible Interference of Offshore Wind Farms in the German North
Sea,” Marine Ecology Progress Series, vol. 383 (2009), pp. 295-307; Michael Dähne et al., “Effects of Pile-Driving on
Harbour Porpoises (Phocoena phocoena) at the First Offshore Wind Farm in Germany,” Environmental Research
Letters, vol. 8, no. 2 (2013), 025002, pp. 1-16.
43 Offshore wind structures may disrupt natural atmospheric and oceanic processes, such as the frequency of ocean
mixing or wind patterns.
44 Electric power cables, such as those used in OWFs, are sources of electromagnetic fields, which are made up of
induced electric and magnetic fields. Some animals (e.g., whales, bats, sea turtles) can detect electric and/or magnetic
fields and use naturally occurring fields to support essential life functions, such as navigating and searching for prey.
Essential life functions of certain animals may be disrupted by human-induced fields. DOE, U.S. Offshore Wind
Synthesis of Environmental Effects Research: Electromagnetic Field Effects on Marine Life, June 30, 2022.
45 See Haylet Farr et al., “Potential Environmental Effects of Deepwater Floating Offshore Wind Energy Facilities,”
Ocean and Coastal Management, vol. 207 (2021), p. 3 (hereinafter referred to as Farr et al., “Potential Environmental
Effects”); and Johan van der Molen et al., “Predicting the Large-Scale Consequences of Offshore Wind Turbine Array
Development on a North Sea Ecosystem,” Continental Shelf Research, vol. 85, no. 1 (June 2014), p. 61 (hereinafter
referred to as Van der Molen et al., “Predicting the Large-Scale Consequences”).
46 Ibon Galparsoro et al., “Reviewing the Ecological Impacts of Offshore Wind Farms,” npj Ocean Sustainability, vol.
1, no. 1 (August 2022), p. 2 (hereinafter referred to as Galparsoro et al., “Reviewing the Ecological Impacts”); Fiona
Hogan et al., Fisheries and Offshore Wind Interactions: Synthesis of Science, National Oceanic and Atmospheric
(continued...)
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derived from the North Sea) show that most impacts (e.g., habitat alteration) occur within the
immediate vicinity of the wind turbine array, with other impacts (e.g., noise effects) extending up
to tens of kilometers outside the array.47 Some of these analyses use land-based wind energy
observations to model potential offshore wind scenarios, and other analyses extrapolate
observations from existing OWFs (again, mostly in the North Sea) to planned offshore wind
energy projects. Other potential impacts are informed by laboratory studies mimicking conditions
(e.g., noise levels) often associated with offshore wind projects. The sections below discuss the
potential OWF impacts (both adverse and beneficial) to the ocean environment and selected
wildlife.
Table 1. Potential Impacts Associated with Offshore Wind Energy Projects
(as documented in federal agency reports and the scientific literature)
Animal
Oceanic
Habitat
Collision
Noise
Water
Type
Change
Alteration
Risk
EMF Effects
Effects
Quality
Marine
—
Y
Y
—
Y
Y
Mammals
Invertebrates
Y
Y
—
Y
Y
Y
Fish
—
Y
Y
Y
Y
Y
Sea Turtles
—
Y
Y
—
Y
Y
Birds
Y
Y
Y
—
—
Y
Bats
—
—
Y
Y
Y
—
Source: CRS, using various sources, including Fiona Hogan et al., Fisheries and Offshore Wind Interactions: Synthesis
of Science, National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service
(NMFS), NOAA Technical Memorandum NMFS-NE-291, March 2023.
Notes: EMF = electromagnetic field; Y = documented impact;—= undocumented in federal reports or the
scientific literature or not observed. The table provides a general summary of the potential impacts from
offshore wind farm projects on marine animals, species dependent on marine resources, or species that travel
over the ocean. The table does not indicate the direction (i.e., adverse or beneficial) or magnitude of change,
risk, or impact.
Ocean Environment
OWF operation may affect aspects of the local ocean environment. Regional hydrodynamic
processes (e.g., ocean mixing and distribution of ocean nutrients) may be influenced by wind
wakes produced by aerodynamic drag from wind turbine blades; wind wakes are disturbances in
the atmosphere that form behind a structure through which air passes.48 In general, the effects of a
wind wake produced by an offshore wind structure depend on atmospheric stability, wind speed,
wind direction, and oceanographic conditions.49

Administration (NOAA), National Marine Fisheries Service (NMFS), NOAA Technical Memorandum NMFS-NE-291,
March 2023, pp. 1-383 (hereinafter referred to as Hogan et al., Fisheries and Offshore Wind Interactions).
47 Van der Molen et al., “Predicting the Large-Scale Consequences,” p. 60.
48 Nils Christiansen et al., “Tidal Mitigation of Offshore Wind Wake Effects in Coastal Seas,” Frontiers in Marine
Science, vol. 9 (October 2022), p. 1 (hereinafter referred to Christiansen et al., “Tidal Mitigation”).
49 Travis Miles et al., “Interactions of Offshore Wind on Oceanographic Processes,” in Fisheries and Offshore Wind
Interactions: Synthesis of Science, NOAA NMFS, NOAA Technical Memorandum NMFS-NE-291, March 2023, p. 51,
https://repository.library.noaa.gov/view/noaa/49151 (hereinafter referred to as Miles et al., “Interactions of Offshore
Wind”).
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Changes in wind speeds associated with OWFs can influence ocean stratification—the vertical
distribution of heat (or another ocean property) that produces horizontal water layers of different
densities. Some marine species require a specific temperature range for their habitat and will
track the vertical movement of thermal layers.50 In addition, stratification can affect the
distribution of salinity and primary productivity in the water column.51 Primary productivity is the
process by which marine phytoplankton use solar energy and atmospheric CO2 to form organic
matter, which makes up the base of the marine food chain.
Some modeling studies show a reduction in average ocean current velocities near OWFs.52
Reduced surface current velocities may increase the amount of carbon buried in seabed sediments
because sediments are not being disturbed as much by water movement as they would be if
surface current velocities were faster.53 One potential consequence of increased carbon burial in
seabed sediments is a drop in oxygen levels at the water-seafloor interface, which could affect
seafloor-dwelling marine life.54 Certain areas of the North Sea exhibit an estimated 10% increase
of carbon burial at OWF locations.55
Some researchers highlight the challenge of separating natural oceanographic variability or
oceanographic change associated with climate change from the impacts of OWFs in observational
studies.56
Effects of Climate Change on the Ocean
Scientific data show that the combustion of fossil fuels accounts for the majority of global anthropogenic carbon
dioxide (CO2) emissions.a Renewable energies (e.g., offshore wind energy) provide one approach to reduce
emissions from the energy sector while continuing to meet society’s demand for energy services.b The
construction of renewable energy infrastructure and operation of these technologies may have immediate impacts
on the local environment, which stakeholders may weigh against the potential of these energies to help offset the
effects of climate change. In addition, some stakeholders have encouraged decisionmakers and federal agencies to
include climate change risks facing the ocean and certain marine animals (e.g., whales) in their analyses of offshore
energy projects in environmental impact statements.c
The ocean absorbs atmospheric CO2. Since the 1980s, the ocean has likely absorbed between 20% and 30% of
total anthropogenic CO2 emissions, resulting in ocean acidification.d Ocean acidification and other consequences
of increasing anthropogenic CO2 emissions have affected marine fisheries, the marine tourism and recreation
sector, and global food security. Climate change has impacted the global ocean in the following ways (the list
below is not exhaustive).e
•
Over the 20th century and continuing today, global sea surface temperatures have increased as the ocean
absorbs more heat.f
•
The global average sea level has been slowly rising because of melting continental ice and the thermal
expansion of ocean water due to its warming.g
•
Glacial and sea-ice melt, as well as increased precipitation associated with climate change, are freshening
near-surface ocean waters, thereby contributing to weaker ocean circulation.h
•
Because warm water holds less dissolved gas than cold water, the ocean is holding less dissolved oxygen as a
result of global ocean warming.i

50 Ibid., p. 52.
51 Christiansen et al., “Tidal Mitigation,” p. 2.
52 For example, Ute Daewel et al., “Offshore Wind Farms Are Projected to Impact Primary Production and Bottom
Water Deoxygenation in the North Sea,” Communications Earth & Environment, vol. 3, no. 292 (November 2022), p. 4
(hereinafter referred to as Daewel et al., 2022).
53 Ibid., p. 5.
54 Ibid.
55 Ibid.
56 For example, Miles et al., “Interactions of Offshore Wind,” p. 52.
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•
As the surface of the ocean absorbs more CO2, the pH of seawater decreases in a process referred to as
ocean acidification.j
Sources:
a. Intergovernmental Panel on Climate Change (IPCC), “Summary for Policymakers,” in Climate Change 2023:
Synthesis Report, eds. Core Writing Team, Hoesung Lee, and José Romero, 2023, p. 4.
b. Ibid., p. 21 and Figure SPM.7.
c. Letter from University of Columbia, Sabin Center for Climate Change Law, to Karen Baker, Program Chief,
Office of Renewable Energy, Bureau of Ocean Energy Management, January 15, 2023,
https://climate.law.columbia.edu/sites/default/files/content/
Attachment%201%20Sabin%20Center%20Comments%20on%20Empire%20Wind%20DEIS.pdf.
d. IPCC, “Summary for Policymakers,” in The Ocean and Cryosphere in a Changing Climate: A Special Report of the
Intergovernmental Panel on Climate Change, eds. Hans-Otto Pörtner et al., 2019, p. 9.
e. National Oceanic and Atmospheric Administration, “Understanding Our Changing Climate,”
https://www.fisheries.noaa.gov/insight/understanding-our-changing-climate.
f.
Environmental Protection Agency, “Climate Change Indicators: Sea Surface Temperature,”
https://www.epa.gov/climate-indicators/climate-change-indicators-sea-surface-temperature.
g. IPCC, “Summary for Policymakers,” in Changing Climate 2021: The Physical Science Basis, eds. Valerie Masson-
Delmotte et al., 2021, p. SPM-14.
h. Ibid., p. SPM-6.
i.
T. L. Frölicher et al., “Contrasting Upper and Deep Ocean Oxygen Responses to Protracted Global
Warming,” Global Biogeochemical Cycles, vol. 34, no. 8 (August 2020), p. 1.
j.
For more information on ocean acidification, see CRS Report R47300, Ocean Acidification: Frequently Asked
Questions, by Caitlin Keating-Bitonti and Eva Lipiec.
Marine Mammals
Certain activities associated with offshore wind development may affect marine mammals. The
scientific literature generally has not found long-term impacts from offshore wind development
on marine mammals, although short-term interference effects associated with site assessment
activities and construction have led to some concerns from scientists and stakeholders.57 OWF
construction involves numerous activities that can generate high sound pressure levels, with pile-
driving in particular producing intense impulses that may induce marine mammal hearing
impairment or loss at close range and may disrupt marine mammal behavior at ranges up to tens
of kilometers.58 Marine mammals, including pinnipeds and cetaceans,59 use sound for foraging,
orientation, and communication. As a result, underwater sound resulting from site
characterization (i.e., G&G surveys)60 and construction may disturb marine mammals and disrupt
their behavioral patterns.61

57 Siddharth S. Kulkarni and David J. Edwards, “A Bibliometric Review on the Implications of Renewable Offshore
Marine Energy Development on Marine Species,” Aquaculture and Fisheries, vol. 7, no. 2 (2022), pp. 211-222
(hereinafter referred to as Kulkarni and Edwards, “Bibliometric Review”).
58 See footnote 42.
59 Pinnipeds include species of the order Pinnipedia (e.g., seals and sea lions). Cetaceans include species of the
infraorder Cetacea (e.g., dolphins and whales).
60 BOEM, G&G Fact Sheet.
61 Madsen et al., “Wind Turbine Underwater Noise”; NOAA, “Takes of Marine Mammals Incidental to Specified
Activities; Taking Marine Mammals Incidental to Marine Site Characterization Surveys in the New York Bight,” 88
Federal Register 42322-42341, 2023.
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Auditory and displacement effects from pile-driving have been observed or may occur in
porpoises, harbor seals, bottlenose dolphins, and other marine mammals.62 A May 2023 National
Oceanic and Atmospheric Administration (NOAA) biological opinion (BiOp) for the Atlantic
Shores South Offshore Wind Project off New Jersey noted that the behavior of endangered North
Atlantic right whales, fin whales, and sei whales could be adversely disrupted by—but would not
be injured by—noise and activities around the OWFs.63 As an example of a behavioral change,
studies suggest that noise from pile-driving activities may negatively affect foraging in some
harbor porpoises by decreasing their fish catch success rates and increasing their termination of
fish catching attempts.64
Some stakeholders have expressed concerns about human-induced noise sources (e.g., underwater
noise associated with offshore wind surveys or pile-driving) displacing marine mammal mothers
from calves, which may have implications for future reproduction and survival.65 Technological
modifications to OWFs may reduce both sound levels and distances at which observed behavioral
responses may occur in marine mammals.66
Some stakeholders also have raised concerns about collision risks with offshore wind energy
structures and potential effects associated with underwater power transmission cables.67 Large
cetaceans could collide with structures or become entangled in mooring cables, power
transmission cables, or anchor lines.68 Baleen whales have been identified as having the greatest
risk of entanglement, particularly on catenary moorings where the lines are not taut but rely on
gravity to create tension (Figure 2).69 Marine mammals that are disoriented from loud noise or
poor water clarity (i.e., increased turbidity) may have an increased risk of collision. In addition,
investigators have raised concerns that EMFs generated by OWF power transmission cables may

62 Helen Bailey et al., “Assessing Underwater Noise Levels During Pile-Driving at an Offshore Windfarm and Its
Potential Effects on Marine Mammals,” Marine Pollution Bulletin, vol. 60, no. 6 (2010), pp. 888-897; Paul M.
Thompson et al., “Framework for Assessing Impacts of Pile-Driving Noise from Offshore Wind Farm Construction on
a Harbour Seal Population,” Environmental Impact Assessment Review, vol. 43 (2013), pp. 73-85; Debbie J. F. Russell
et al., “Avoidance of Wind Farms by Harbour Seals Is Limited to Pile Driving Activities,” Journal of Applied Ecology,
vol. 53, no. 6 (2016), pp. 1642-1652; Thomsen et al., Effects of Offshore Wind Farm Noise; Madsen et al., “Wind
Turbine Underwater Noise.”
63 BOEM, Office of Renewable Energy Programs, Atlantic Shores Offshore Wind Atlantic Shores South Project
Biological Assessment for National Marine Fisheries Service, May 2023, p. 105, https://www.boem.gov/sites/default/
files/documents/renewable-energy/state-activities/Atlantic%20Shores%20South%20NMFS%20BA.pdf.
64 Foraging responses of porpoises may vary among individuals. Ronald A. Kastelein et al., “Effect of Pile-Driving
Playback Sound Level on Fish-Catching Efficiency in Harbor Porpoises (Phocoena phocoena),” Aquatic Mammals,
vol. 45, no. 4 (2019), pp. 398-410.
65 Harwood et al., “Acoustic Disturbance for Marine Mammals.”
66 For example, the use of direct drive technology instead of a gear box may reduce sound levels. Direct drive
technology powers a generator directly by the rotor, whereas a gear box is placed between a low-speed rotor and an
electrical generator to increase rotor speed before feeding to the generator. Frank Thomsen and Uwe Stöber,
“Operational Underwater Sound from Future Offshore Wind Turbines Can Affect the Behavior of Marine Mammals,”
Journal of the Acoustical Society of America, vol. 151, no. 4 (2022), pp. A239-A239; Edis Osmanbasic, “The Future of
Wind Turbines: Comparing Direct Drive and Gearbox,” April 7, 2020, https://www.engineering.com/story/the-future-
of-wind-turbines-comparing-direct-drive-and-gearbox.
67 Amy E. Davis, Potential Impacts of Ocean Energy Development on Marine Mammals in Oregon,” 2010, pp. 1-25,
https://ir.library.oregonstate.edu/concern/technical_reports/jh343z21h.
68 Ibid.
69 S. Benjamins et al., Understanding the Potential for Marine Megafauna Entanglement Risk from Renewable Marine
Energy Developments, Scottish Natural Heritage, Scottish Natural Heritage Commissioned Report No. 791, 2014,
https://ore.exeter.ac.uk/repository/bitstream/handle/10871/21616/Understanding?sequence=1; Farr et al., “Potential
Environmental Effects.”
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adversely affect some marine animals.70 However, according to various studies, no impacts of
EMFs on marine mammals have been documented.71
Figure 2. Examples of Floating Wind Mooring Systems

Sources: ABC Moorings, “Mooring Systems,” http://abc-moorings.weebly.com/mooring-systems.html; S.
Benjamins et al., Understanding the Potential for Marine Megafauna Entanglement Risk from Renewable Marine Energy
Developments, Scottish Natural Heritage, Scottish Natural Heritage Commissioned Report No. 791, 2014,
https://ore.exeter.ac.uk/repository/bitstream/handle/10871/21616/Understanding?sequence=1.
Notes: Basic floating platform types—such as spar, semisubmersible, and tension-leg platforms—require
mooring systems to tether or anchor the platform to the seafloor. In a catenary mooring system, the most
common mooring system in shallow waters, the mooring lines hang freely between the floating unit and the
seabed, relying on gravity to create tension. In a taut-leg mooring system, the pretensioned mooring lines intersect
at an angle (typically 30-40 degrees) at the seabed, for which there is less entanglement risk but which can
require vertical load anchors and add design complexities. A mooring system with attributes of both catenary
and taut leg is referred to as a semi-taut mooring system (not pictured), which can reduce the anchor distance
from the turbine without changing anchor types or substructure design.
To minimize short-term disruptions to marine mammals, developers could take mitigation
actions. Such actions could include
• establishing monitored safety zones that lead to shut-down or low-power
operations if certain animals enter these zones;
• using noise reduction gear such as bubble curtains or hydro-sound dampeners
around pile-driving; and/or
• implementing noise source modifications or operational parameters, such as soft
starts.72
Less-targeted mitigation actions also have been proposed, including adopting best management
practices for construction and adhering to seasonal work restrictions to protect marine wildlife at

70 Klaus Lucke et al., “Literature Review of Offshore Wind Farms with Regard to Marine Mammals,” in Ecological
Research on Offshore Wind Farms: International Exchange of Experiences, Project No.: 804 46 001, Part B:
Literature Review of the Ecological Impacts of Offshore Wind Farms, eds. Catherine Zucco et al. (Bonn, Germany:
Bundesamt für Naturschutz, 2006), pp. 199-284; Andrea E. Copping et al., “Potential Environmental Effects of Marine
Renewable Energy Development—The State of the Science,” Journal of Marine Science and Engineering, vol. 8, no.
11 (2020), Article 879.
71 Farr et al., “Potential Environmental Effects”; Kulkarni and Edwards, “Bibliometric Review.”
72 Ursula K. Verfuss et al., “Review of Offshore Wind Farm Impact Monitoring and Mitigation with Regard to Marine
Mammals,” in The Effects of Noise on Aquatic Life II, eds. Arthur N. Popper and Anthony Hawkins (New York, NY:
Springer, 2016), pp. 1175-1182; Christine Erbe, Rebecca Dunlop, and Sarah Dolman, “Effects of Noise on Marine
Mammals,” in Effects of Anthropogenic Noise on Animals, eds. Hans Slabbekoorn et al. (New York, NY: Springer,
2018), pp. 277-309. The term soft start is applied to the gradual, or incremental, increase in hammer blow energy from
the initiation of piling activity until required blow energy is reached for installation of each pile. Maximum hammer
blow energy may not be required to complete pile installation. Ørsted, Hornsea Project Four: Preliminary
Environmental Information Report (PEIR), F2.5: Outline Marine Mammal Mitigation Protocol, Version A, July 2019,
p. 4, https://orstedcdn.azureedge.net/-/media/www/docs/corp/uk/hornsea-project-four/01-formal-consultation/
additional-application-information/hornsea-four-peir-outline-marine-mammal-mitigation-protocol.pdf.
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sensitive life stages. For example, some experts have proposed limiting pile-driving activities
during spawning and other biologically sensitive periods to reduce potential noise impacts.73 In
some studies, mitigation actions were correlated with reduced harm for certain species. Research
into strategies for reducing the impacts of offshore wind projects on marine mammals is ongoing.
Some stakeholders, including Members of Congress, have expressed concern that projects
nonetheless would cause unacceptable harm to marine wildlife and have sought further actions,
such as a GAO study of offshore wind’s environmental impacts.74
Marine mammals are protected by the Marine Mammal Protection Act (MMPA).75 In addition,
certain marine mammal species may be listed under the Endangered Species Act (ESA);76 actions
that affect these species may trigger the prohibitions and requirements imposed by that act. For
more information on these statutory regimes, see “Marine Mammal Protection Act” and
“Endangered Species Act,” below.
Whales
Some stakeholders and public officials, including some Members of Congress,77 have raised
concerns about potential connections between offshore wind development and whale mortality. In
particular, reports of whale deaths off the northeast Atlantic coast, especially off New Jersey, in
early 2023 raised questions about whether increased mortality could be due to offshore wind
G&G surveys.78 Eight humpback whale strandings occurred in New Jersey between January and
November 2023, compared with four strandings in 2022 and none in 2021.79 Since 2016, elevated
humpback whale mortalities have occurred along the U.S. Atlantic coast from Maine to Florida.
In April 2017, NOAA’s National Marine Fisheries Service (NMFS) declared an unusual mortality
event—unexpected strandings involving significant die-offs of any marine mammal that demand
an immediate response—involving humpback whales.80 Humpback whale strandings have
continued along the Atlantic coast; between January and November 2023, 37 humpback whale
strandings occurred.81 In May 2023, some Members of Congress wrote a letter to GAO requesting
that the agency look into the potential impacts of offshore wind energy development and
associated infrastructure in the North Atlantic.82 In June 2023, GAO announced it would study the

73 Linus Hammar, Andreas Wikström, and Sverker Molander, “Assessing Ecological Risks of Offshore Wind Power on
Kattegat Cod,” Renewable Energy, vol. 66 (2014), pp. 414-424 (hereinafter referred to as Hammar, Wikström, and
Molander, “Assessing Ecological Risks”).
74 For example, H.R. 1, §20118.
75 16 U.S.C. §§1361-1423h.
76 16 U.S.C. §§1531 et seq.
77 See H.Res. 239 in the 118th Congress.
78 Amanda Oglesby and Dan Radel, “Whale Deaths Along East Coast Prompt 12 NJ Mayors’ Call for Offshore Wind
Farm Moratorium,” Cape Cod Times, January 31, 2023; Krik Moore, “Poll Finds Whale Strandings Drive Down New
Jersey Support for Offshore Wind,” National Fisherman, May 13, 2023.
79 NOAA NMFS, “2016-2023 Humpback Whale Unusual Mortality Event Along the Atlantic Coast,”
https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2023-humpback-whale-unusual-mortality-event-
along-atlantic-coast (hereinafter NOAA NMFS, “2016-2023 Humpback Whale Unusual Mortality Event”).
80 Ibid.
81 Ibid.
82 Representatives Bruce Westerman, Chris Smith, Andy Harris, and Jeff van Drew to Gene L. Dodaro, Comptroller
General, U.S. GAO, May 15, 2023, https://chrissmith.house.gov/uploadedfiles/north_atlantic_wind_study_letter_-
_gao.pdf.
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environmental impacts of OWFs and any connections to whale mortalities, along with other
potential impacts.83
Neither BOEM nor NOAA has found evidence that offshore wind development-related site
characterization surveys caused recent whale mortalities.84 Assessments by NOAA scientists have
not found any connections between G&G surveys for offshore wind energy projects and marine
mammal deaths along the U.S. Atlantic coast.85 On the basis of roughly 90 necropsy
investigations of whales from 2016 to 2023, NOAA found 40% of documented whale mortalities
and serious injuries resulted from vessel strikes or fishing gear entanglements.86 A 2021 BOEM
risk assessment of OWF development on the Atlantic OCS suggested a positive relationship
between vessel speed and potential strike risk for vessel types that operate in support of OWFs
both in transit and in wind farm areas (i.e., increased strike risk for OWF service vessels traveling
at higher vessel speeds).87
In response to increased public concern, New Jersey’s Department of Environmental Protection
issued a statement clarifying that “as of August 2023, no offshore wind-related construction
activities have taken place in waters off the New Jersey coast.”88 In addition, marine mammal
surveys conducted as part of the New Jersey Department of Environmental Protection ecological
baseline study documented few large whales in the vicinity of OWF development areas off New
Jersey.89 However, because whales are difficult to see and spend much of their time submerged,
the research techniques used to track them may miss whales that are present and therefore might
underestimate whale abundance and density in the study areas.90 On October 17, 2023, Cape May
County, NJ—along with environmental, hotel, and seafood industry groups—filed a lawsuit in
U.S. District Court against NOAA and BOEM.91 The lawsuit claims in part that these agencies
did not fully consider the potential harm to the environment and wildlife from offshore wind
projects. The lawsuit seeks to reverse BOEM and NOAA’s approval of Ocean Wind I, an offshore
wind project located about 13 nautical miles southeast of Atlantic City, NJ.92

83 Wayne Parry, “Congressional Watchdog Agency to Probe Offshore Wind Impacts,” Associated Press News, June 15,
2023.
84 NOAA NMFS, “Frequent Questions—Offshore Wind and Whales,” https://www.fisheries.noaa.gov/new-england-
mid-atlantic/marine-life-distress/frequent-questions-offshore-wind-and-whales (hereinafter NOAA NMFS, “Frequent
Questions”); BOEM, “Renewable Energy Fact Sheet: Offshore Wind Activities and Marine Mammal Protection,”
https://www.boem.gov/sites/default/files/documents/renewable-energy/state-activities/
Offshore%20Wind%20Activities%20and%20Marine%20Mammal%20Protection_1.pdf.
85 NOAA NMFS, “Frequent Questions.”
86 NOAA NMFS, “2016-2023 Humpback Whale Unusual Mortality Event.”
87 Mary Jo Barkaszi et al., Risk Assessment to Model Encounter Rates Between Large Whales and Vessel Traffic from
Offshore Wind Energy on the Atlantic OCS, BOEM, OCS Study BOEM 2021-034, 2021, pp. 1-54,
https://tethys.pnnl.gov/sites/default/files/publications/BOEM_2021-034.pdf.
88 State of New Jersey, Department of Environmental Protection, “2016-2023 Humpback Whale Unusual Mortality
Event,” https://dep.nj.gov/humpback-whale-unusual-mortality-event/.
89 Amy D. Whitt et al., “Abundance and Distribution of Marine Mammals in Nearshore Waters off New Jersey, USA,”
Journal of Cetacean Research and Management, vol. 15, no. 1 (2015), pp. 45-59.
90 Ibid.
91 County of Cape May v. United States, No. 1:23-cv-21201 (D.N.J. Oct. 17, 2023). See Cape May County, “Cape May
County Files Lawsuit Challenging Approval of Ørsted’s Ocean Wind 1 Project,” October 17, 2023,
https://capemaycountynj.gov/CivicAlerts.aspx?AID=1423.
92 Ørsted has ceased development of Ocean Wind I (and Ocean Wind II) for financial reasons, but the lawsuits over the
permitting are ongoing. See Ørsted, “Ørsted Ceases Development of Its U.S. Offshore Wind Projects Ocean Wind 1
and 2, Takes Final Investment Decision on Revolution Wind, and Recognizes DKK 28.4 Billion Impairments,”
October 31, 2023, https://orsted.com/en/company-announcement-list/2023/10/oersted-ceases-development-of-its-us-
offshore-wind-73751.
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Marine Invertebrates
OWFs may have a mixed effect on invertebrates that live in marine environments (e.g., clams,
crabs, squids), with potential positive and negative consequences for such species. In particular,
the installation of foundations alters the seafloor habitat but also creates a new habitat in the water
column, thereby impacting different species in various ways. In addition, noise and EMF effects
associated with OWF activities seem to have neutral to negative effects on invertebrate species.
An offshore wind foundation, after its installation, may act as an artificial reef and may be rapidly
colonized by various macroalgae (i.e., seaweed) and encrusting invertebrate organisms (e.g.,
mussels, barnacles) that attach to the submerged foundation (Figure 3).93 In general, mussels and
barnacles, which consume organic particles suspended in the water column (i.e., suspension
feeders), attach to the foundation near the surface of the ocean.94 The artificial reef created by the
foundation may attract more marine life than natural reefs. 95 However, the attraction of
suspension feeders to OWF foundations may alter the surrounding water quality by reducing the
availability of nutrients in the water column (Figure 3).96

93 Traditionally, artificial reefs are human-made structures deliberately placed in the sea to mimic characteristics of
natural reefs to increase local biodiversity. Structures installed on the OCS such as oil and gas platforms, coastal
defense constructions, and OWFs also have become artificial reefs, although they were not built for this purpose.
Steven Degraer et al., “Offshore Wind Farm Artificial Reefs Affect Ecosystem Structure and Functioning: A
Synthesis,” Oceanography, vol. 33, no. 4 (2020), pp. 49-50 (hereinafter referred to as Degraer et al., “Offshore Wind
Farm Artificial Reefs”); and Silvana N. R. Birchenough and Zoë L. Hutchinson, “Shellfish and Crustaceans,” in
Fisheries and Offshore Wind Interactions: Synthesis of Science, NOAA NMFS, NOAA Technical Memorandum
NMFS-NE-291, March 2023, https://repository.library.noaa.gov/view/noaa/49151 (hereinafter referred to as
Birchenough and Hutchinson, “Shellfish and Crustaceans”).
94 Farr et al., “Potential Environmental Effects,” p. 6.
95 Galparsoro et al., “Reviewing the Ecological Impacts,” p. 3.
96 Degraer et al., “Offshore Wind Farm Artificial Reefs,” pp. 52, 55.
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Figure 3. Schematic of Artificial Reef on Offshore Wind Foundation

Source: Steven Degraer et al., “Offshore Wind Farm Artificial Reefs Affect Ecosystem Structure and
Functioning: A Synthesis,” Oceanography, vol. 33, no. 4 (2020), pp. 48-57.
Notes: The water current flows from left to right in the schematic. Mussels, sea anemones, and barnacles (in
order of left to right in the circular zoomed-in illustrations on the right side of the schematic) are suspension-
feeding organisms that commonly attach to the foundation structure. As plankton and detritus suspended in the
water (the left-most circular zoomed-in illustration) flow past the foundation, they are consumed by these
organisms, resulting in less material suspended in the water column. Less material in the water column (i.e.,
decreased turbidity) would increase the depth of light penetration. In addition, fecal pellets from the suspension-
feeding organisms would accumulate around the base of the foundation, which would increase the amount of
organic matter in the seafloor sediment while supporting greater population densities and biodiversity of visible
seafloor organisms (i.e., macrobenthos).
Offshore wind foundations typically alter the seafloor habitat at the base of the foundation. In
general, the installation of offshore wind foundations replaces soft sediment habitats with hard
substrates, leading to a biodiversity loss of species adapted to living on (or in) soft sediment
environments.97 Conversely, one study estimated a 4,000-fold biomass increase when comparing
the original seafloor biomass with the new biomass.98 The study attributed the increase in biomass
to the artificial reef.99 Some studies found that foundations may attract an increased number of
crabs and lobsters, suggesting the offshore wind foundations act as aggregation sites and nursery
grounds for these crustaceans.100

97 Chen Li et al., “Offshore Wind Energy and Marine Biodiversity in the North Sea: Life Cycle Impact Assessment for
Benthic Communities,” Environmental Science & Technology, vol. 57, no. 16 (2023), pp. 6455-6464.
98 Degraer et al., “Offshore Wind Farm Artificial Reefs,” p. 51.
99 Ibid., p. 52.
100 See Birchenough and Hutchinson, “Shellfish and Crustaceans,” p. 93.
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In addition, OWFs may attract nonindigenous species to the area, because a foundation anchored
in the open ocean provides a new site favorable to encrusting marine invertebrates.101 No threats
to indigenous communities from nonindigenous invertebrate species associated with OWFs have
been documented.102
Some crustaceans (e.g., lobster, crabs) and mollusks (e.g., clams, scallops, and squids) may react
to underwater sound associated with offshore wind energy projects. For example, a laboratory
study that exposed lobsters and hermit crabs to noise effects similar to that of offshore wind
construction found that lobsters exhibited reduced mobility and altered feeding activities.103
Another laboratory study assessing the responses of squids to OWF noise observed changes in
squid behaviors.104 Squids and other cephalopods likely use underwater sound from the local
environment to aid navigation and to detect predators and prey.105 In addition, prolonged exposure
to noise physically damaged the auditory structures of some squid species.106
In addition, EMF produced by the electricity transmitted through undersea power transmission
cables associated with OWFs may affect some invertebrate species. Some shellfish (e.g., spiny
lobster) use geomagnetic fields for navigation. The potential impacts of EMF on mollusks and
crustaceans are not well studied.
Certain marine invertebrate species may be listed under the ESA and are subject to the
prohibitions and requirements imposed by that act. For more information on those protections,
see “Endangered Species Act,” below.
Fishes107
Offshore wind installations may affect fish and fisheries in multiple ways and at different
scales.108 Perceptions of whether certain impacts are positive or negative vary across species and
among stakeholders.109
As with some marine mammals, offshore wind energy projects may pose collision risks for large
fishes, such as sturgeons, especially those that are disoriented because of loud noise or decreased
water clarity (i.e., increased turbidity).110
Fishes may be attracted to the artificial reef effect created by offshore wind energy foundations.
In general, the food and habitat associated with the artificial reef effect attract demersal fishes
(e.g., cod, flatfishes, whiting) and increase the abundance and diversity of finfish in the OWF

101 Degraer et al., “Offshore Wind Farm Artificial Reefs,” p. 51.
102 Degraer et al., “Offshore Wind Farm Artificial Reefs,” p. 52.
103 Birchenough and Hutchinson, “Shellfish and Crustaceans,” p. 94.
104 Ibid., p. 95.
105 Ibid., p. 94.
106 Ibid., p. 95.
107 Fish refers to one species of fish; fishes refer to more than one species of fish.
108 16 U.S.C. §1802(13) defines a fishery as “one or more stocks of fish which can be treated as a unit for purposes of
conservation and management and which are identified on the basis of geographical, scientific, technical, recreational,
and economic characteristics; and any fishing for such stocks.”
109 Andrew B. Gill et al., “Setting the Context for Offshore Wind Development Effects on Fish and Fisheries,”
Oceanography, vol. 33, no. 4 (2020), pp. 118-127 (hereinafter referred to as Gill et al., “Setting the Context”).
110 BOEM, Ocean Wind: An Ørsted & PSEG Project, Appendix I – Atlantic Sturgeon Supplemental Material, April
2023, p.4, https://www.boem.gov/sites/default/files/documents/renewable-energy/state-activities/
OCW01_COP_Volume%20III_Appendix%20I_20230518.pdf.
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area.111 In addition, OWFs may increase the local abundance of economically important highly
migratory finfishes (e.g., sharks, tunas).112
Behavioral reactions to underwater sound have been observed in fish at distances up to tens of
kilometers from sites of offshore wind construction and operation.113 For example, juvenile
seabass exhibited disrupted schooling behaviors during playbacks of pile-driving noise.114 No
direct fish mortality from offshore wind pile-driving activity has been observed, but some
individuals of cod experienced barotrauma, an injury of a body part or organ as a result of
changes in pressure, to their swim bladders,115 as well as internal bleeding and a high degree of
abnormal swimming behavior.116 During power production, noise generated by wind turbines can
be detected by fish sensitive to sound pressure (e.g., herring, salmon, cod) at distances up to
several kilometers; other fish species may detect the turbine noises only within a 10-meter
distance.117 These acoustic impacts from turbines appear to be restricted to masking
communication and orientation signals rather than causing physiological damage.118
EMFs associated with OWFs, including their undersea power transmission cables, also may
impact fishes. EMFs may cause behavioral change in some fish, such as altered navigation,
migratory, or homing behaviors.119 For example, experimental studies show that small sharks,
such as dogfish, are attracted to EMFs from wind power installations that are comparable in

111 NOAA defines demersal as “living in close relation with the bottom and depending on it. Cods, groupers, crabs, and
lobsters are demersal resources. The term usually refers to the living mode of the adult, i.e., demersal fish” (NOAA,
NOAA Fisheries Glossary, June 2006, p. 10). Elizabeth T. Methratta et al., “Offshore Wind Development in the
Northeast U.S. Shelf Large Marine Ecosystem,” Oceanography, vol. 33, no. 4 (2020), pp. 16-27 (hereinafter referred to
as Methratta et al., “Offshore Wind Development in the Northeast U.S. Shelf”); Ralf van Hal, Arie Benjamin Griffioen,
and O. A. van Keeken, “Changes in Fish Communities on a Small Scale, an Effect of Increased Habitat Complexity by
an Offshore Wind Farm,” Marine Environmental Research, vol. 126 (2017), pp. 26-36; and Hogan et al., Fisheries and
Offshore Wind Interactions, pp. 66-91. Claus J. G. Stenberg et al., “Long-Term Effects of an Offshore Wind Farm in
the North Sea on Fish Communities,” Marine Ecology Progress Series, vol. 528 (2015), pp. 257-265; Elizabeth T.
Methratta and William R. Dardick, “Meta-Analysis of Finfish Abundance at Offshore Wind Farms,” Reviews in
Fisheries Science and Aquaculture, vol. 27, no. 2 (2019), pp. 242-260; Hogan et al., Fisheries and Offshore Wind
Interactions, pp. 66-75.
112 Methratta et al., “Offshore Wind Development in the Northeast U.S. Shelf.”
113 Mathias H. Andersson, “Offshore Wind Farms: Ecological Effects of Noise and Habitat Alteration on Fish,”
Doctoral Dissertation, Stockholm University, 2011, pp. 28-34.
114 James E. Herbert-Read et al., “Anthropogenic Noise Pollution from Pile-Driving Disrupts the Structure and
Dynamics of Fish Shoals,” Proceedings of the Royal Society B: Biological Sciences, vol. 284, no. 1863 (2017),
20171627, pp. 1-9.
115 Thomas J. Carlson, “Barotrauma in Fish and Barotrauma Metrics,” in The Effects of Noise on Aquatic Life, eds.
Arthur N. Popper and Anthony Hawkins (New York, NY: Springer, 2012), pp. 229-234.
116 Annelies De Backer et al., “Swim Bladder Barotrauma in Atlantic Cod When in Situ Exposed to Pile Driving,” in
Environmental Impacts of Offshore Wind Farms in the Belgian Part of the North Sea: A Continued Move Towards
Integration and Quantification, eds. Steven Degraer et al. (Brussels, Belgium: Royal Belgian Institute of Natural
Sciences, OD, Natural Environment, Marine Ecology and Management Section, 2017), pp. 25-37.
117 Ibid.
118 T. Aran Mooney, Mathias H. Andersson, and Jenni Stanley, “Acoustic Impacts of Offshore Wind Energy on
Fisheries Resources,” Oceanography, vol. 33, no. 4 (2020), pp. 82-95; Magnus Wahlberg and Håkan Westerberg,
“Hearing in Fish and Their Reactions to Sounds from Offshore Wind Farms,” Marine Ecology Progress Series, vol.
288 (2005), pp. 295-309.
119 Zoë L. Hutchinson, David H. Secor, and Andrew B. Gill, “The Interaction Between Resource Species and
Electromagnetic Fields Associated with Electricity Production by Offshore Wind Farms,” Oceanography, vol. 33, no. 4
(2020), pp. 96-107; Methratta et al., “Offshore Wind Development in the Northeast U.S. Shelf.”
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magnitude to fields produced by dogfish prey. As another example, experimental studies of skates
show increased exploratory and foraging behaviors in response to EMFs.120
Grease, lubricant, and oil emissions from operational OWFs may have local effects to fishes and
other marine wildlife.121 Potential risks associated with lubricant spills from major turbine
breakdowns include exposure to toxic substances among early fish recruits, including cods.122 To
mitigate the potential for an exposure event, investigators recommend precautionary approaches
such as using less toxic or biodegradable lubricants to minimize effects to marine life.123
The Magnuson-Stevens Fishery Conservation and Management Act is the primary statute for
management of harvested marine fish populations and their habitats.124 Certain marine fish
species may be listed under the ESA and are subject to the prohibitions and requirements imposed
by that act. For more information on those protections, see “Endangered Species Act,” below.
Fisheries125
The marine ecosystem includes all associated living species, environmental elements, and human
components, such as marine fisheries (including fishing communities).126 Experts consider marine
fisheries as part of the marine ecosystem, given their direct influences on ecosystem functioning,
living marine resource populations, and human socioeconomics.127 OWFs may influence
localized fish aggregating dynamics (i.e., the gathering of a single fish species or multiple species
of fishes during a particular period of time), which may influence marine fisheries.128 Local
increases in fish abundance may increase commercial and recreational fishing effort at OWFs

120 Zoë L. Hutchinson et al., “Anthropogenic Electromagnetic Fields (EMF) Influence the Behaviour of Bottom-
Dwelling Marine Species,” Scientific Reports, vol. 10, no. 1 (2020), 4219, pp. 1-15.
121 Rickard Arvidsson and Sverker Molander, Screening Environmental Risk Assessment of Grease and Oil Emissions
from Off-Shore Wind Power Plants, Chalmers University of Technology, Report No. 2012:7, 2010, pp. 1-39,
https://core.ac.uk/download/pdf/70593839.pdf.
122 Hammar, Wikström, and Molander, “Assessing Ecological Risks”; O. Mauricio Hernandez C. et al., “Environmental
Impacts of Offshore Wind Installation, Operation and Maintenance, and Decommissioning Activities: A Case Study of
Brazil,” Renewable and Sustainable Energy Reviews, vol. 144 (2021), 110994, pp. 1-18. Most lubricant components
have low water solubility, and fish eggs and larvae generally drift below the surface, which may reduce exposure to
potentially harmful substances adhered to the surface.
123 Hammar, Wikström, and Molander, “Assessing Ecological Risks.”
124 16 U.S.C. §§1801-1891d.
125 The Magnuson-Stevens Fishery Conservation and Management Act, under 16 U.S.C. §1802(13), defines a fishery as
“one or more stocks of fish which can be treated as a unit for purposes of conservation and management and which are
identified on the basis of geographical, scientific, technical, recreational, and economic characteristics; and any fishing
for such stocks.”
126 J. S. Link et al., “Keeping Humans in the Ecosystem,” ICES Journal of Marine Science, vol. 74, no. 7 (2017), pp.
1947-1956.
127 Ibid; M. Sinclair et al., “Responsible Fisheries in the Marine Ecosystem,” Fisheries Research, vol. 58, no. 3 (2002),
pp. 255-265; J. S. Link and A. R. Marshak, “Characterizing and Comparing Marine Fisheries Ecosystems in the United
States: Determinants of Success in Moving Toward Ecosystem-Based Fisheries Management,” Reviews in Fish Biology
and Fisheries, vol. 29 (2019), pp. 23-70.
128 Kevin D. Friedland et al., “Forage Fish Species Prefer Habitat Within Designated Offshore Wind Energy Areas in
the U.S. Northeast Shelf Ecosystem,” Marine and Coastal Fisheries, vol. 15, no. 2 (2023), e10230, pp. 1-20; G. van
Hoey et al., Overview of the Effects of Offshore Wind Farms on Fisheries and Aquaculture, Publications Office of the
European Union, 2021, pp. 1-99, https://op.europa.eu/en/publication-detail/-/publication/3f2134f9-b84f-11eb-8aca-
01aa75ed71a1/language-en (hereinafter referred to as Van Hoey et al., 2021).
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(i.e., the amount of time and fishing power used to harvest fish),129 particularly for rod and reel or
trap/pot fisheries.130
Fishing and other activities may need to avoid certain zones during the construction of OWFs.131
Certain vessels towing fishing gear may need to avoid the OWF area during its operation.132
Federal agencies may prohibit certain fishing practices, such as bottom trawling, near OWFs for
safety reasons.133 The prohibition of certain fishing activities may reduce disturbances to benthic
fish habitats (i.e., species living on or in seafloor sediments) from fishing activities.134 The
displacement of fishing effort may affect fish species in other locations and may increase local
competition for space among fishing vessels.135 Studies of the North Sea suggest that any
potential refugium effects (i.e., protection from fishery harvest) to fishes do not become apparent
until nearly a decade after the establishment of an OWF.136
Sea Turtles
Although the potential effects of OWFs on sea turtles remain unclear,137 researchers and
stakeholders suspect sea turtles may experience effects similar to those experienced by marine
mammals (e.g., collision risks, acoustic effects on hearing and behavior).138

129 NOAA, NOAA Fisheries Glossary, June 2006, p. 12.
130 Ibid.
131 Maximilian Felix Schupp et al., “Fishing Within Offshore Wind Farms in the North Sea: Stakeholder Perspectives
for Multi-Use from Scotland and Germany,” Journal of Environmental Management, vol. 279 (2021), p. 2.
132 Ibid.
133 Kaitlynn Webster and Read Porter, “Legal Limits on Recreational Fishing near Offshore Wind Facilities,” Sea
Grant Law Fellow Publications, 2020, https://docs.rwu.edu/law_ma_seagrant/98.
134 Van Hoey et al., Overview of the Effects of Offshore Wind Farms; Galparsoro et al., “Reviewing the Ecological
Impacts,” p. 3.
135 Gill et al., “Setting the Context”; Methratta et al., “Offshore Wind Development in the Northeast U.S. Shelf.”
136 Some experts consider refugium effects for species in offshore wind farm areas as being related to a combination of
fisheries exclusion and increased food availability. Annelies De Backer, Jolien Buyse, and Kris Hostens, “A Decade of
Soft Sediment Epibenthos and Fish Monitoring at the Belgian Offshore Wind Farm Area,” in Environmental Impacts of
Offshore Wind Farms in the Belgian Part of the North Sea: Empirical Evidence Inspiring Priority Monitoring,
Research, and Management, Memoirs on the Marine Environment, eds. Steven Degraer et al. (Brussels, Belgium:
Royal Belgian Institute of Natural Sciences, OD Natural Environment, 2020), pp. 79-113; Annelies de Backer, Liam
Wyns, and Kris Hostens, “Continued Expansion of the Artificial Reef Effect in Soft-Sediment Epibenthos and
Demersal Fish Assemblages in Two Established (10 Years) Belgian Offshore Wind Farms,” in Environmental Impacts
of Offshore Wind Farms in the Belgian Part of the North Sea: Attraction, Avoidance and Habitat Use at Various
Spatial Scales. Memoirs on the Marine Environment, eds. Steven Degraer et al. (Brussels, Belgium: Royal Belgian
Institute of Natural Sciences, OD Natural Environment, 2021), pp. 60-68.
137 CSA Ocean Sciences, Inc., Technical Report: Assessment of Impacts to Marine Mammals, Sea Turtles, and ESA-
Listed Fish Species, Revolution Offshore Wind Farm, Prepared for Revolution Wind, LLC, February 2023, pp. 98-104,
https://www.boem.gov/sites/default/files/documents/renewable-energy/state-activities/
App_Z1_MarineMammalSeaTurtleandFishTechnicalReport_CSA_V15_27Feb2023.pdf (hereinafter referred to as CSA
Ocean Sciences,, Technical Report); Morgan Wing Goodale and Anita Milman, “Cumulative Adverse Effects of
Offshore Wind Energy Development on Wildlife,” Journal of Environmental Planning and Management, vol. 59, no. 1
(2016), pp. 1-21 (hereinafter referred to as Goodale and Milman, “Cumulative Adverse Effects”).
138 Sarah K. Henkel, Robert M. Suryan, and Barbara A. Lagerquist, “Marine Renewable Energy and Environmental
Interactions: Baseline Assessments of Seabirds, Marine Mammals, Sea Turtles and Benthic Communities on the
Oregon Shelf,” in Marine Renewable Energy Technology and Environmental Interactions, eds. Mark A. Shields,
Andrew I. L. Payne (London: Dordrecht, 2014), pp. 93-110 (hereinafter referred to as Henkel, Suryan, and Lagerquist,
“Marine Renewable Energy and Environmental Interactions”); CSA Ocean Sciences, Technical Report.
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Sea turtles may be attracted to offshore wind structures because of beneficial foraging and shelter
opportunities.139 At the same time, increased vessel traffic associated with offshore wind energy
development may result in higher collision risks for sea turtles.140 Displacement of sea turtles
from natural habitats in response to OWF noise, or potentially from alteration of sea turtles’
migration patterns due to EMFs, may increase their susceptibility to vessel collisions.141 Lights
used on offshore wind turbines and construction vessels also may disrupt movements of sea
turtles and their hatchlings, which tend to move toward the brightest light.142 In addition,
researchers have raised concerns about impacts from OWF development on sea turtle nesting and
breeding grounds, including habitat fragmentation, among other potential effects.143
Certain sea turtle species are listed under the ESA and are subject to the protections and
requirements of that act. For more information on those protections, see “Endangered Species
Act.”
Birds
Bird collisions with rotating turbine blades are one of the most high-profile and debated potential
impacts of land-based wind farms and OWFs. Researchers view migratory bird species as more
vulnerable to OWF collisions than other birds.144 Bird species that congregate during breeding
periods or pre-migration “staging” periods might be vulnerable if congregations are located near
OWFs.145 For any individual bird, collision risk at land-based or offshore wind farms depends on
flight path, flight height, and avoidance or attractance behaviors.146 Each of these behaviors is
described in more detail below.
• Flight Path: Many bird species have migratory pathways that they follow during
spring and fall migration periods. These pathways, which are essentially
migratory bird highways, may overlap with the locations of OWFs.
• Flight Height: Bird flight height can depend on species-specific factors, as well
as variables such as the distance of the flight, whether it is day or night, air
pressure, and prevailing wind direction.

139 CSA Ocean Sciences, Technical Report, p. 102.
140 Goodale and Milman, “Cumulative Adverse Effects.
141 Ibid.; Henkel, Suryan, and Lagerquist, “Marine Renewable Energy and Environmental Interactions.”
142 Josep Lloret et al., “Unraveling the Ecological Impacts of Large-Scale Offshore Wind Farms in the Mediterranean
Sea,” Science of the Total Environment, vol. 824 (2022), 153803, pp. 1-12.
143 Helen Bailey, Kate L. Brookes, and Paul M. Thompson, “Assessing Environmental Impacts of Offshore Wind
Farms: Lessons Learned and Recommendations for the Future,” Aquatic Biosystems, vol. 10, no. 1 (2014), pp. 1-13;
CSA Ocean Sciences, Technical Report.
144 Chris B. Thaxter et al., “Bird and Bat Species’ Global Vulnerability to Collision Mortality at Wind Farms Revealed
Through a Trait-Based Assessment,” Proceedings of the Royal Society B: Biological Sciences, vol. 284, no. 1862
(2017), p. 7 (hereinafter referred to as Thaxter et al., “Bird and Bat Species’ Global Vulnerability to Collision”).
145 For example, Joris Everaert and Eric W. M. Stienen, “Impact of Wind Turbines on Birds in Zeebrugge (Belgium),”
Biodiversity and Conservation, vol. 16, no. 12 (2007), pp. 3345-3359 (hereinafter referred to as Everaert and Stienen,
“Impact of Wind Turbines on Birds”).
146 Robert W. Furness et al., “Assessing Vulnerability of Marine Bird Populations to Offshore Wind Farms,” Journal of
Environmental Management, vol. 119 (2013), pp. 56-66 (hereinafter referred to as Furness et al., “Assessing
Vulnerability of Marine Bird Populations”).
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• Avoidance or Attractance: Certain species can avoid or be attracted to OWFs
for various reasons, such as changes in food availability near turbines, or can
avoid or be attracted to individual turbine structures or blades.147
How bird species exhibit these behaviors can determine collision risk, as can the environment
(e.g., wind, visibility).148 Behavioral and environmental interactions (e.g., strong winds causing
migratory birds to fly closer to blades) also affect collision risk.149
There is little monitoring of bird collisions with OWFs in the United States, in part because U.S.
OWFs are relatively recent. Information about the potential scale of bird collisions with U.S.
OWFs may be derived from studies of European OWFs and land-based wind farms.150 Some
research estimates that hundreds of thousands of individual birds are killed at land-based turbines
annually.151 Many of the factors that influence collision risk for land-based wind farms also
influence risk for OWFs. However, land-based wind energy turbine structures are typically
smaller than offshore turbine structures and require more turbine structures per megawatt at lower
hub heights compared with offshore wind turbine structures.152 As a result, many experts
anticipate fewer collision risks with offshore wind structures than with land-based ones. The U.S.
Fish and Wildlife Service (FWS) reports that mortality rates vary among wind energy facilities
and across regions. FWS also notes that most birds killed at land-based wind farms are songbirds,
which occupy offshore areas only during migration.153
Several bird species that occupy areas in and near OWFs during some part of their life cycle can
be found in both the United States and Europe.154 A study of European OWFs suggests that
displacement of some bird species from OWFs is more common than mortality events.155 Some
studies have noted the need to distinguish temporary versus permanent avoidance of an area,
which can cause population declines.156
BOEM and cooperating agencies have required offshore wind developers to undertake mitigation
activities, monitoring, and reporting to reduce potential harm to wildlife from collisions with

147 For example, Shanshan Zhao et al., “Effect of Wind Farms on Wintering Ducks at an Important Wintering Ground
in China Along the East Asian–Australasian Flyway,” Ecology and Evolution, vol. 10, no. 17 (2020), pp. 9567-9580;
Carlos D. Santos et al., “Factors Influencing Wind Turbine Avoidance Behaviour of a Migrating Soaring Bird,”
Scientific Reports, vol. 12, no. 1 (2022), Article 6441.
148 Furness et al., “Assessing Vulnerability of Marine Bird Populations.”
149 Ommo Hüppop et al., “Bird Migration Studies and Potential Collision Risk with Offshore Wind Turbines,” Ibis, vol.
148, no. s1 (March 2006), pp. 90-109.
150 For example, Jonne C. Kleyheeg-Hartman et al., “Predicting Bird Collisions with Wind Turbines: Comparison of
the New Empirical Flux Collision Model with the SOSS Band Model,” Ecological Modelling, vol. 387, no. 8 (2018),
pp. 144-153.
151 Scott R. Loss et al., “Estimates of Bird Collision Mortality at Wind Facilities in the Contiguous United States,”
Biological Conservation, vol. 168 (2013), pp. 201-209.
152 According to DOE’s 2023 Land-Based Market Report, U.S. cumulative wind capacity was 144.2 gigawatts in 2022,
including 0.042 gigawatts of offshore wind (DOE, Land-Based Wind Market Report: 2023 Edition, DOE/GO-102023-
6055, August 2023, p. 4). According to the U.S. Geological Survey’s (USGS’s) U.S. Wind Turbine Database, as of
May 2023, 72,731 turbines are located in 43 states plus Guam and Puerto Rico (USGS, “The U.S. Wind Turbine
Database,” https://eerscmap.usgs.gov/uswtdb/).
153 U.S. Fish and Wildlife Service (FWS), “Wind Energy,” https://www.fws.gov/node/266177.
154 Bird species that occur both in the United States and in Europe include the northern gannet; several species of tern
(Sterna spp.); and seabird species with large geographic ranges, such as shearwaters, petrels, and other species in the
family Procellariidae.
155 Stefan Garthe et al., “Large-Scale Effects of Offshore Wind Farms on Seabirds of High Conservation Concern,”
Scientific Reports, vol. 13 (2023), 4779.
156 For example, Everaert and Stienen, “Impact of Wind Turbines on Birds.”
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OWFs.157 For instance, to reduce collision risk for birds, offshore wind developers’ mitigation
actions may include the following:
• Deploying taller turbine models with turbine blades that are largely above typical
flight heights158
• Painting turbine blades black159
• Installing lights near turbines
• Automating rotors to stop rotating turbine blades during times of high bird
passage rates
• Causing the installations to make additional noise to scare birds from an area160
Although most concerns about impacts to birds focus on collisions during the operational stage of
an OWF, some birds may be impacted in other ways. For example, bird species that feed
underwater, such as diving ducks or species that plunge dive, may be affected by changes in food
availability in or near OWFs.161 For some species, OWFs may serve as a barrier to reaching
feeding, breeding, or resting areas.162 Table 2 describes selected bird species that may be
vulnerable to impacts from OWFs because of small population sizes, geographic range, species-
specific behaviors, or some combination of these factors.
Impacts of OWFs on birds may give rise to liability under certain federal statutes. Migratory birds
may be protected by the Migratory Bird Treaty Act of 1918 (MBTA).163 Other bird species may
be listed under the ESA and subject to its protections. For more information on the regulatory
frameworks governing these species, see “Relevant Statutes for Federal Agency Actions Related
to Offshore Wind Projects,” below.

157 See, for example, Section 4 and Appendix A of BOEM, Record of Decision: Vineyard Wind 1 Offshore Wind
Energy Project Construction and Operations Plan, May 10, 2021.
158 Alison Johnston et al., “Modelling Flight Heights of Marine Birds to More Accurately Assess Collision Risk with
Offshore Wind Turbines,” Journal of Applied Ecology, vol. 51, no. 1 (2014), pp. 31-41.
159 One research study found that bird deaths decline by 70% after painting a single turbine blade black (leaving the
other blades unpainted). See Roel May et al., “Paint It Black: Efficacy of Increased Wind Turbine Rotor Blade
Visibility to Reduce Avian Fatalities,” Ecology and Evolution, vol. 10, no. 16 (February 2020), pp. 8927-8935.
160 For example, DOE, National Renewable Energy Laboratory, “Minimization of Motion Smear: Reducing Avian
Collisions with Wind Turbines,” subcontractor report, August 2003, https://www.nrel.gov/docs/fy03osti/33249.pdf.
161 For example, a 2012 study found changes in abundance of sandeel, a forage fish for many seabirds (Mikael van
Deurs et al., “Short- and Long-Term Effects of an Offshore Wind Farm on Three Species of Sandeel and Their Sand
Habitat,” Marine Ecology Progress Series, vol. 458 (2012), pp. 169-180).
162 Eric W. M. Stienen et al., “Trapped Within the Corridor of the Southern North Sea: The Potential Impact of
Offshore Wind Farms on Seabirds,” in Birds and Wind Farms: Risk Assessment and Mitigation, eds. Manuela de
Lucas, Guyonne F. E. Janss, and Miguel Ferrer (Quercus, Madrid, Spain, 2007), pp. 71-80.
163 16 U.S.C. §703.
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Table 2. Selected Bird Species That May Be Impacted by Offshore Wind Projects
Common Name
Federal
(scientific name)
Protections
Characteristics That Cause Vulnerability
Roseate terns
ESA;a MBTA
Individuals make foraging trips between nesting sites on oceanic
(Sterna dougallii dougallii)
islands and near-shore environments and migrate long distances
over the U.S. OCS.
Northern gannet
MBTA
The species’ geographic range overlaps the U.S. OCS, and individuals
(Morus bassanus)
plunge dive at up to 40 miles/hour from heights of up to 100 feet.
Cahow
ESA; MBTA
The species nests only in Bermuda and makes long foraging flights
(Pterodroma cahow)
that intersect the U.S. EEZ. Less than 200 remain globally in 2023.
Blackpoll warbler
MBTA
Individuals make nonstop, transoceanic flights that overlap the U.S.
(Setophaga striata)
OCS during spring and fall migration.
Ashy storm petrel
MBTA
Species breeds on offshore islands across a limited geographic range
(Hydrobates homochroa)
from Central to Southern California. Individuals use a specific
feeding behavior that involves flying near the ocean surface.
Brown pelican
MBTA
Individuals feed by plunge diving in coastal areas of the Atlantic and
(Pelecanus occidentalis)
Pacific Oceans. The species’ geographic range overlaps the U.S.
OCS.
Source: S. M. Billerman et al., eds., Birds of the World, Cornell Laboratory of Ornithology (2022),
https://birdsoftheworld.org/bow/home; and Emma C. Kelsey et al., “Collision and Displacement Vulnerability to
Offshore Wind Energy Infrastructure Among Marine Birds of the Pacific Outer Continental Shelf,” Journal of
Environmental Management, vol. 227 (2018), https://doi.org/10.1016/j.jenvman.2018.08.051.
Notes: EEZ = exclusive economic zone; ESA = Endangered Species Act (16 U.S.C. §§1531 et seq.); OCS = outer
continental shelf; MBTA = Migratory Bird Treaty Act of 1918 (16 U.S.C. §703). The U.S. OCS is the area of the
seafloor located generally between 3 and 200 nautical miles from the shoreline.
a. The northeast population in the United States is listed as endangered under the ESA.
Bats
Little is known about OWF collision risk for bat species, but some modeling studies suggest
higher collision rates for bats than birds.164 In the United States, several species of bat are
migratory. Bats typically migrate over land, but some species (e.g., red bats) have been detected
flying over the open ocean.165 Research suggests that long-distance dispersing bats have the
highest collision rates compared with other bats.166 Some scientists have proposed that bats may
be attracted to OWFs because the OWFs emit light (which attracts insects) and are prominent
landmarks.167 Other factors, such as high offshore wind speeds, may discourage bats from flying
near OWFs.168
Certain bat species are listed under the ESA and are subject to the prohibitions and requirements
of that act. For more information on those protections, see “Endangered Species Act.”

164 Thaxter et al., “Bird and Bat Species’ Global Vulnerability to Collision,” p. 7.
165 Shaylyn K. Hatch et al., “Offshore Observations of Eastern Red Bats (Lasiurus borealis) in the Mid-Atlantic United
States Using Multiple Survey Methods,” PLOS One, vol. 8, no. 12 (2013), e83803.
166 Thaxter et al., “Bird and Bat Species’ Global Vulnerability to Collision,” p. 7.
167 Donald I. Solick and Christian M. Newman, “Oceanic Records of North American Bats and Implications for
Offshore Wind Energy Development in the United States,” Ecology and Evolution, vol. 11, no. 4 (2021), pp. 14433-
14447.
168 Ibid.
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Relevant Statutes for Federal Agency Actions
Related to Offshore Wind Projects
Several federal agencies have responsibilities relevant to the development, permitting, and
environmental oversight of offshore wind development. All federal agencies bear responsibility
for assessing certain environmental effects of their actions—including issuing permits—under
general statutory frameworks such as the National Environmental Policy Act (NEPA)169 and the
ESA. Certain federal agencies have been further tasked with administering specific statutes that
aim to protect particular aspects of the environment or certain natural resources. This section of
the report outlines certain statutes that may impose procedural or substantive requirements on
federal agencies intended to assess and potentially mitigate the environmental effects of wind
projects in federal waters. Separately, state agencies typically must permit and approve portions
of federal projects, such as power transmission cables, that cross through state waters.170 Federal
law also authorizes state governments to review federal projects for consistency with coastal
protection programs under the Coastal Zone Management Act.171
In general, BOEM has primary responsibility for administering offshore renewable energy
development on the OCS, with several other agencies playing a role in the permitting and
environmental review process. The U.S. Army Corps of Engineers (USACE) has the authority to
review and regulate certain activities, such as the installation of structures and laying of power
transmission cables.172 Other agencies that have a permitting, approval, and enforcement role in
the development of offshore renewable energy include DOI’s Bureau of Safety and
Environmental Enforcement (BSEE), the Federal Aviation Administration, the Environmental
Protection Agency, NOAA, and the U.S. Coast Guard (USCG).173 In response to E.O. 14008,
“Tackling the Climate Crisis at Home and Abroad,” BOEM and USACE entered into a
partnership in support of planning and reviewing renewable energy projects on the Atlantic
OCS.174
National Environmental Policy Act
NEPA requires federal agencies to evaluate the impacts of major federal actions that significantly
affect the human environment.175 NEPA is a procedural statute that requires federal agencies to

169 42 U.S.C. §§4321 et seq.
170 BOEM, “Agency Approval,” https://www.boem.gov/renewable-energy/agency-approval.
171 16 U.S.C. §§1451-1466.
172 The U.S. Army Corps of Engineers (USACE) has the authority to regulate (1) activities that affect navigation from
the mean high-water line at the shore out to three nautical miles and the seabed of the OCS and (2) dredging and filling
impacts of project segments out to three nautical miles of the territorial sea. USACE exercises this authority pursuant
to, inter alia, Section 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. §403), which addresses structures and work
in or affecting the course, condition, or capacity of navigable waters; these waters extend from the mean high-water
line to three nautical miles from the shore. USACE’s Section 10 authority extends to the seabed of the OCS for certain
activities―artificial islands, installations, and other devices (43 U.S.C. §1333(e)). This extension results in the agency
regulating the navigation impacts of installations on the seafloor of the OCS. USACE also has authority pursuant to
Section 404 of the Clean Water Act to authorize activities that may discharge dredge or fill material into waters of the
United States (33 U.S.C. §1344).
173 BOEM, “Agency Approval,” https://www.boem.gov/renewable-energy/agency-approval.
174 BOEM, “BOEM and USACE Collaborate to Meet Offshore Wind Goals,” press release, June, 14, 2021,
https://www.boem.gov/boem-and-usace-collaborate-meet-offshore-wind-goals.
175 For an overview of the environmental review process under the National Environmental Policy Act (NEPA; 42
U.S.C. §§4321 et seq.), see CRS In Focus IF12417, Environmental Reviews and the 118th Congress, by Kristen Hite.
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take a “hard look” at the environmental consequences of their proposed actions and consider
alternatives to those actions.176 The statute requires federal agencies undertaking this process to
consult with and solicit comments from any other federal agencies with “jurisdiction by law or
special expertise” about the environmental impact involved.177 NEPA also requires federal
agencies to make these analyses available to the public.178
The level of review and analysis NEPA requires varies based on the anticipated level of impacts
of the proposed action. For actions expected to have significant impacts on the human
environment, the lead federal agency must prepare an EIS.179 In its EIS, the lead agency must
assess (1) reasonably foreseeable environmental impacts of the proposal, (2) reasonably
foreseeable but unavoidable adverse environmental effects, (3) a reasonable range of alternatives
to the proposed action, (4) the relationship between the short-term uses of the environment and
maintenance of long-term productivity, and (5) any irretrievable resource commitments involved
if the proposal is implemented.180 In general, an EIS should be completed within two years,181
during which the lead agency releases a draft EIS for comment from other agencies and the
public. A final EIS must respond to comments from agencies and the public by modifying the
proposal, developing alternatives, or explaining why comments do not merit substantive replies or
changes.182 Once an agency reaches a final decision on the action it wishes to take (i.e., the
proposed action or an alternative, including no action), it issues a record of decision (ROD).183
As the agency responsible for offshore wind leasing on the OCS,184 BOEM conducts NEPA
evaluations of multiple actions at successive stages of the leasing process, often employing a
tiered evaluation to allocate the burden while avoiding redundancies.185 BOEM generally
conducts its most detailed NEPA review when lessees file COPs. A COP details actions the lessee
proposes to take to build and operate the wind farm. BOEM serves as the lead agency for the
preparation of an EIS analyzing the COP, in cooperation with other agencies (discussed below)
that also have responsibilities related to the COP.186 EISs prepared by BOEM for offshore wind
COPs have considered potential marine ecosystem impacts of the proposed wind development,
such as potential impacts from animals’ collisions with offshore wind energy structures or
construction vessels, noise associated with project development, displacement from traditional
habitat, and other effects. On the basis of these evaluations, BOEM has often required, as
conditions of COP approvals, that developers undertake monitoring, reporting, and mitigation to
address anticipated impacts. For instance, a developer’s mitigation activities could include

176 Robertson v. Methow Valley Citizens Council, 490 U.S. 332, 350 (1989).
177 42 U.S.C. §4332(C).
178 42 U.S.C. §4332; 40 C.F.R. §1503.1.
179 42 U.S.C. §4332; 40 C.F.R. Part 1502.
180 42 U.S.C. §4332.
181 42 U.S.C. §4336a(g)(1)(A).
182 40 C.F.R. §1503.4.
183 40 C.F.R. §1505.2.
184 43 U.S.C. §1337(p).
185 For more information, see CRS Report R46970, U.S. Offshore Wind Energy Development: Overview and Issues for
the 118th Congress, by Laura B. Comay and Corrie E. Clark; and CRS Report R40175, Offshore Wind Energy
Development: Legal Framework, by Adam Vann.
186 For examples of completed EISs, see BOEM, “National Environmental Policy Act and Offshore Renewable
Energy,” https://www.boem.gov/renewable-energy/national-environmental-policy-act-and-offshore-renewable-energy.
The EIS analyses address impacts from infrastructure construction and operations in the primary project area as well as
associated transmission cables connecting to shore.
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installing bird deterrent devices on turbines and adhering to seasonal work restrictions to protect
marine wildlife at sensitive life stages, among many others.
Several agencies cooperate with BOEM during the NEPA process. BSEE cooperates with BOEM
by overseeing implementation, monitoring, and assessment of the mitigation measures developed
to avoid potential environmental impacts, among other tasks.187 NMFS, FWS, USACE, and other
agencies have participated in the EISs as cooperating or participating agencies,188 in connection
with these agencies’ permitting responsibilities under the MMPA, ESA, Section 10 of the Rivers
and Harbors Act of 1899,189 Section 404 of the Clean Water Act,190 and other laws. BOEM also
consults with state agencies in developing the EIS. Some agencies—in particular, NMFS and
USACE—have joined with BOEM and DOI in issuing the RODs for some EISs, so that the
RODs authorize not only BOEM’s approval of the COP but also the permits required from NMFS
and/or USACE.191
Fixing America’s Surface Transportation Act
BOEM’s responsibilities include coordinating interagency review and permitting timelines under
provisions of the Fixing America’s Surface Transportation (FAST) Act.192 Title 41 of the FAST
Act (known as FAST-41) requires certain types of coordination among federal agencies for
environmental review and permitting of specified infrastructure projects. Many federal offshore
wind projects are covered under FAST-41.193
FAST-41 and its implementing guidance require that the designated lead agency for
environmental review of a covered project (i.e., BOEM, in the case of offshore wind projects)
coordinate the project’s review timetable.194 The mechanism for coordination is the Federal
Infrastructure Permitting Dashboard (FIPD).195 Cooperating agencies with review and permitting
responsibilities (e.g., NMFS, USACE) participate in the BOEM-led EIS and in maintaining the
FIPD timetable.196

187 Bureau of Safety and Environmental Enforcement, “NEPA Compliance,” https://www.bsee.gov/what-we-do/
environmental-compliance/environmental-programs/nepa-compliance.
188 A cooperating agency “means any Federal agency, other than a lead agency, [that] has jurisdiction by law or special
expertise with respect to any environmental impact” involved in a proposed project or project alternative (40 C.F.R.
1508.5). A participating agency means any federal agency, other than the lead agency, or any nonfederal agency that
may have an interest with respect to the environmental review process in the project (23 U.S.C. §139(d)).
189 33 U.S.C. §403.
190 33 U.S.C. §1344.
191 NMFS has co-issued all five records of decision (RODs) completed to date for offshore wind COPs. USACE has
signed onto two RODs and, in three cases, has issued its own ROD for the USACE permits, while incorporating by
reference the analysis in the BOEM-led EISs.
192 42 U.S.C. §§4370m–4370m12.
193 The definition of covered projects includes projects that require “authorization or environmental review by a Federal
agency involving construction of infrastructure for renewable or conventional energy production.” (42 U.S.C.
§4370m(6)).
194 Office of Management and Budget and Council on Environmental Quality, “Guidance to Federal Agencies
Regarding the Environmental Review and Authorization Process for Infrastructure Projects,” January 13, 2017,
https://www.permits.performance.gov/sites/permits.dot.gov/files/2019-10/Official%20Signed%20FAST-
41%20Guidance%20M-17-14%202017-01-13.pdf.
195 Federal Infrastructure Permitting Dashboard (FIPD), https://www.permits.performance.gov/about.
196 42 U.S.C. §4370m-4(a).
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FAST-41 sets the goal for coordinated review and permitting of covered projects to generally be
completed within two years.197 Despite this goal, the review and approval process has taken
longer than two years for each of the five offshore wind projects covered by FAST-41 that have
progressed to the point of COP approval. These projects are Vineyard Wind 1 off Massachusetts,
South Fork Wind off Rhode Island and Massachusetts, Ocean Wind 1 off New Jersey, Revolution
Wind off Rhode Island and Massachusetts, and the Coastal Virginia Offshore Wind Commercial
Project off Virginia.198
Some Members of Congress and other stakeholders contend that offshore wind projects would
benefit from additional permitting efficiencies beyond the FAST-41 requirements.199 These
advocates contend that a more expedited process would assist states in meeting renewable power
commitments, facilitate a transition away from fossil fuel energy, and help build a domestic
supply chain. The Fiscal Responsibility Act of 2023 amended aspects of NEPA, including
directing agencies to rely on a single document during the environmental review.200 Other
stakeholders have expressed an opposing concern that wind permitting may be proceeding too
quickly, with insufficient consideration of potential impacts, including those on the marine
environment and ecosystem.201
Marine Mammal Protection Act
The MMPA provides for the protection of marine mammals from extinction or depletion due to
human activities. Of relevance to offshore wind activities, the MMPA prohibits the take of marine
mammals, with certain exceptions, absent authorization from NOAA or FWS. Under the MMPA,
to take a marine mammal means to “harass, hunt, capture, or kill” the animal or to attempt to do
any of those acts.202 The MMPA further defines harassment as
any act of pursuit, torment, or annoyance which—(i) has the potential to injure a marine
mammal or marine mammal stock in the wild; or (ii) has the potential to disturb a marine
mammal or marine mammal stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding, feeding, or
sheltering.203
The MMPA and its implementing regulations give NOAA the authority to authorize incidental
takes (i.e., unintentional, but not unexpected, takes) of small numbers of marine mammals within
a specified geographic region during particular activities.204 Authorization of incidental takes to a
given party may be given through

197 42 U.S.C. §4370m-1(c)(1)(C). FAST-41 also establishes a process for resolving disputes that may affect the
permitting timetable (42 U.S.C. §4370m-2(c)(2)(C)).
198 Department of the Interior, “Biden-Harris Administration Approves Fourth Major Offshore Wind Project,” press
release, August 22, 2023, https://www.doi.gov/pressreleases/biden-harris-administration-approves-fourth-major-
offshore-wind-project.
199 For example, the joint explanatory statement for FY2021 BOEM appropriations in P.L. 116-260 stated, “The
Committees on Appropriations remain concerned that unreliable schedules for permit processing and environmental
reviews have created uncertainty for the long-term viability of offshore wind development.” U.S. Congress, Joint
Explanatory Statement of the Committee of Conference on H.R. 133: Committee on Appropriations, House of
Representatives, 116th Cong., 2nd Sess., Congressional Record, December 21, 2020, p. H8534.
200 42 U.S.C. §4336a(b).
201 For further discussion, see CRS Report R46970, U.S. Offshore Wind Energy Development: Overview and Issues for
the 118th Congress, by Laura B. Comay and Corrie E. Clark, section on “Permitting Decisions.”
202 16 U.S.C. §1362(13).
203 16 U.S.C. §1362(18).
204 50 C.F.R. §216.
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• an Incidental Harassment Authorization (IHA) for small-scale activities or
activities expected to result only in harassment of marine mammals (e.g., short-
term offshore wind site characterization and construction) or
• a Letter of Authorization (LOA) for larger scale activities or activities that may
cause serious injury or mortality to marine mammals.
Under the MMPA, IHAs must prescribe, as applicable, the permissible means of taking the
marine mammals by harassment, the measures NOAA determines to be necessary to avoid
unmitigable adverse impacts on the species’ availability for taking for subsistence purposes, and
requirements for monitoring and reporting.205 To obtain an IHA, the applicant must submit
information about the planned activity (including dates, duration, and geographic region), the
anticipated impacts on species or stocks of marine mammals and their habitats, the feasibility of
conducting the activity so as to have the least possible adverse impact on the species, and the
manner in which they plan to accomplish the necessary monitoring and reporting.206 For activities
near traditional Arctic subsistence hunting areas or that may affect species or stocks used for
those purposes, additional requirements apply.207 When issuing IHAs, NOAA typically works
with applicants to define appropriate monitoring and mitigation measures to minimize adverse
effects to marine mammals.208
As of November 2023, takes for marine mammals associated with approved offshore wind energy
activities (i.e., site characterization and construction) have been authorized by NOAA in IHAs
and in two LOAs for five-year construction activities off Rhode Island and New Jersey.209
Endangered Species Act
Offshore wind development activities may be subject to requirements under the ESA when those
activities may affect species identified under the act as endangered or threatened (i.e., listed
species) or when they may affect designated critical habitat for such species.210 The ESA aims to
protect threatened and endangered fish, wildlife, and plants from extinction. The act is
administered by FWS, which covers terrestrial, freshwater, and catadromous species,211 and
NMFS, which covers marine species and anadromous fish.212 FWS and NMFS determine which
species qualify as endangered or threatened based on an analysis of threats to the species. When a

205 16 U.S.C. §1371(a)(5)(D)(II).
206 50 C.F.R. §216.104(a).
207 50 C.F.R. §216.104(a)(12).
208 NOAA NMFS, “Apply for an Incidental Take Authorization,” https://www.fisheries.noaa.gov/national/marine-
mammal-protection/apply-incidental-take-authorization; A. Michael Macrander et al., “Convergence of Emerging
Technologies: Development of a Risk-Based Paradigm for Marine Mammal Monitoring for Offshore Wind Energy
Operations,” Integrated Environmental Assessment and Management, vol. 18, no. 4 (2022), pp. 939-949.
209 NOAA is in the process of finalizing the proposed rules for Incidental Harassment Authorizations (NOAA NMFS,
“Incidental Take Authorizations for Other Energy Activities (Renewable/LNG),” https://www.fisheries.noaa.gov/
national/marine-mammal-protection/incidental-take-authorizations-other-energy-activities-renewable). The Marine
Mammal Protection Act also authorizes federal agencies to implement mitigation measures related to the taking of
marine mammals. For example, 16 U.S.C. §1371(a)(5)(D)(ii) states that an incidental take authorization shall prescribe
mitigation measures and requirements for monitoring and reporting of any incidental takes that may affect the
availability of that species for subsistence uses.
210 16 U.S.C. §1533(a)-(b). An endangered species is a species “in danger of extinction throughout all or a significant
portion of its range.” 16 U.S.C. §1532(6). A threatened species is a species “likely to become an endangered species
within the foreseeable future throughout all or a significant portion of its range.” 16 U.S.C. §1532(20).
211 Catadromous species spend most of their lives in freshwater but enter the ocean to spawn (e.g., American eel).
212 Anadromous species spend most of their lives in the ocean but enter freshwater to spawn (e.g., salmon).
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species is listed under the ESA, certain protections and requirements directed at conserving the
species and its ecosystem apply.
Among other things, Section 9 of the ESA prohibits the take of an endangered species, and FWS
or NMFS may extend this prohibition to a threatened species.213 The ESA defines take to mean
“harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect” the species, or to attempt
to do any of those things.214 When taking of a particular listed species would be prohibited, by
statute or by regulation, a person or other entity expecting to take that species in the course of an
otherwise lawful activity (referred to as incidental take) generally must obtain authorization from
FWS or NMFS.215 When no federal agency is involved, such authorization is generally given in
the form of an incidental take permit.216 When one or more federal agencies are involved in the
action, such as the federal permits required for an offshore wind project, the applicant and federal
agencies obtain authorization of any anticipated take through the Section 7 consultation
process.217
Section 7 of the ESA governs review of federal agency actions, such as issuing federal permits,
that may affect listed species or critical habitat. For actions that may adversely affect listed
species, the Section 7 process also is the means of obtaining authorization for any associated
incidental take.218 Actions subject to Section 7 may include infrastructure projects, such as the
installation of offshore wind facilities, undertaken by action agencies or by nonfederal entities
with federal authorization (e.g., permits, contracts) or funding. For example, federal agencies may
be required to consult with NMFS if the installation of an offshore wind facility that they are
carrying out, authorizing, or funding likely would affect listed marine species.
Section 7 requires federal agencies to ensure actions they undertake, authorize, or fund are not
likely to jeopardize listed species or adversely modify designated critical habitat for listed
species.219 To satisfy this mandate, Section 7 generally requires federal agencies to consult with
FWS or NMFS when their proposed actions may affect listed species or critical habitat. A
multistep process, generally referred to as Section 7 consultation, is used to evaluate the effects of
agency actions on listed species and critical habitat and to consider alternative actions that could
minimize those effects.
At the end of a Section 7 consultation, FWS or NMFS issues a BiOp.220 A BiOp states the
agency’s opinion as to whether the proposed action is likely to jeopardize listed species or
adversely modify their designated critical habitat. If the agency concludes that the action may
jeopardize listed species or adversely modify critical habitat, the agency must suggest any
reasonable and prudent alternatives (RPAs) that could avoid jeopardizing listed species or
adversely modifying critical habitat. If the agency concludes the proposed action (or the action as
modified by an RPA) would not jeopardize listed species or adversely modify critical habitat, the
agency includes an incidental take statement (ITS) in the BiOp. The ITS describes the anticipated
impact of any incidental take (i.e., harassing, harming, killing, or otherwise taking the species, as

213 16 U.S.C. §§1538(a)(1), 1533(d).
214 16 U.S.C. §1532(19).
215 16 U.S.C. §§1536, 1539(a)(1)(B).
216 16 U.S.C. §1539(a)(1)(B).
217 16 U.S.C. §1536.
218 16 U.S.C. §1536(o).
219 16 U.S.C. §1536(a)(2).
220 16 U.S.C. §1536(b).
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defined by the ESA, in the course of the otherwise legal action) and provides reasonable and
prudent measures the agency considers necessary to minimize that impact.
BOEM consults with NMFS under Section 7 of the ESA for offshore wind facilities for listed
marine species such as the North Atlantic Right Whale, fin and sei whales, sea turtles, Atlantic
sturgeon, and giant manta rays. BiOps for offshore wind facilities have been issued under the
ESA. For example, on December 18, 2023, NMFS issued a BiOp to BOEM on the effects of the
proposed Atlantic Shores South Offshore Energy Project to be built off the coast of New Jersey.221
The BiOp concluded that the proposed facility is likely to adversely affect, but not jeopardize, the
continued existence of certain listed marine species or to adversely modify critical habitat. The
project includes some measures aimed at minimizing effects on species and other measures to
monitor and report effects of the project on listed species. The ITS also contains measures to
conserve and protect listed species.
Migratory Bird Treaty Act
The MBTA prohibits taking, killing, or possessing species that are part of one or more of the
bilateral migratory bird treaties between the United States and Canada, Mexico, Japan, and
Russia.222 FWS administers the MBTA. Over 1,000 species are protected under the act.223
Violations of the MBTA are subject to criminal penalties.224 U.S. courts are split on whether the
MBTA’s prohibition on taking migratory birds includes take that results from, but is not the
purpose of, another lawful activity (i.e., incidental take).225 FWS currently interprets the MBTA to
prohibit the incidental take of covered migratory birds.226
OWFs may result in the take of migratory birds. For example, a single fatal collision of a covered
species with a turbine would be considered a take.227 To date, no persons or entities have been
prosecuted in the United States under the MBTA for takes related to OWFs. However, in 2013,
Duke Energy Renewables was prosecuted for incidental take from a land-based wind farm in
Wyoming, in part because the company failed to “make all reasonable efforts to build the projects
in a way that would avoid the risk of avian deaths” and to follow FWS “guidance about how wind
project developers could avoid impacts to wildlife.”228 In 2014, PacifiCorp Energy was
prosecuted for incidental take at two land-based wind farms in Wyoming.229 Both companies pled
guilty and were sentenced to pay fines and implement environmental compliance plans.

221 NOAA NMFS, “NOAA Issuing Biological Opinion on the Atlantic Shores South Offshore Energy Project,”
December 18, 2023, https://content.govdelivery.com/bulletins/gd/USNOAAFISHERIES-3802d5d?wgt_ref=
USNOAAFISHERIES_WIDGET_1.
222 16 U.S.C. §703.
223 The list of species that receive protections under the Migratory Bird Treaty Act (MBTA: 16 U.S.C. §703) is
maintained through the regulatory process (50 C.F.R. §10.13).
224 16 U.S.C. §707.
225 For more information on legal interpretations of the MBTA and incidental take, see CRS Report R44694, The
Migratory Bird Treaty Act (MBTA): Selected Legal Issues, by Linda Tsang and Erin H. Ward.
226 In 2021, FWS narrowed its interpretation of “take” under the MBTA to preclude prosecutions for incidental take,
see 86 Federal Register 1134, but this rule was revoked later that year, see 86 Federal Register 54642.
227 16 U.S.C. §703.
228 Department of Justice (DOJ), “Utility Company Sentenced in Wyoming for Killing Protected Birds at Wind
Projects,” press release, November 22, 2013, https://www.justice.gov/opa/pr/utility-company-sentenced-wyoming-
killing-protected-birds-wind-projects.
229 DOJ, “Utility Company Sentenced in Wyoming for Killing Protected Birds at Wind Projects,” press release,
(continued...)
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FWS is also obligated to consult with federal agencies on the implementation of E.O. 13186,
“Responsibilities of Federal Agencies to Protect Migratory Birds.”230 E.O. 13186 directs agencies
to develop a memorandum of understanding with FWS for any projects that may impact species
protected under the MBTA. In addition, FWS has served as a participating agency in the
preparation of final EISs for offshore wind projects.231
Issues for Congress
The full extent of impacts of offshore wind activities on the marine ecosystem of the U.S. OCS
remains unclear, in part because the development of U.S. offshore wind projects is relatively
recent. If interest in the climate mitigation benefits derived from offshore wind energy grows in
the United States and BOEM continues to issue leases for offshore wind development, Congress
may continue to consider how offshore wind energy development may impact the marine
ecosystem and associated species.232 In the 118th Congress, some Members called for additional
research into the potential harm offshore wind projects may cause to marine wildlife or expressed
concern about the potential impacts offshore wind activities might have on other ocean uses (e.g.,
H.R. 1).
Research on the Impacts of Offshore Wind Energy Development
and Mitigation Strategies
The magnitude and direction (i.e., positive or negative) of offshore wind impacts on the marine
ecosystem have yet to be quantified.233 In addition, gaps exist in scientific knowledge about the
interactions between offshore wind turbines and marine species.234 According to one literature
review of the interactions between OWFs and oceanographic conditions, most studies focus on
OWFs in Europe’s North Sea.235 Although these operational OWFs may provide some insight into
the potential impacts of offshore wind development on the U.S. OCS, the continental shelves of
the United States differ from the offshore characteristics of the North Sea.236 Offshore wind
projects on the U.S. OCS are generally sited for deeper waters where turbines are to be spaced at
a greater distance (nearly double) than those in the North Sea. Moreover, the offshore
characteristics of the Gulf of Mexico and the U.S. Atlantic and Pacific Coasts also differ. Some
believe that additional studies, including modeling studies tailored to specific conditions of the
U.S. OCS, are needed to better understand the potential impacts of offshore wind development.237
Section 20115 of H.R. 1 in the 118th Congress would prohibit the Secretary of the Interior from
holding a lease sale for offshore wind energy in certain areas of the U.S. OCS until GAO

December 19, 2014, https://www.justice.gov/opa/pr/utility-company-sentenced-wyoming-killing-protected-birds-wind-
projects-0.
230 E.O. 13186, “Responsibilities of Federal Agencies to Protect Migratory Birds,” 66 Federal Register 3853, January
17, 2001.
231 For example, BOEM, “Notice of Availability of the Empire Offshore Wind Final Environmental Impact Statement,”
88 Federal Register 63615, September 15, 2023.
232 For additional discussion about issues for Congress related to offshore wind and fisheries, see CRS Report R46970,
U.S. Offshore Wind Energy Development: Overview and Issues for the 118th Congress, by Laura B. Comay and Corrie
E. Clark.
233 Hogan et al., Fisheries and Offshore Wind Interactions; and Galparsoro et al., “Reviewing the Ecological Impacts.”
234 Galparsoro et al., “Reviewing the Ecological Impacts.”
235 Miles et al., “Interactions of Offshore Wind ,” p. 54.
236 Refer to the subsection on “Ocean Environment” in this report.
237 Ibid.
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“publishes a report on all the potential adverse effects of wind energy development in such
areas.” Other potential considerations for Congress are the level of research funding provided to
agencies involved in offshore wind projects (e.g., BOEM, Department of Energy, NOAA NMFS)
and the locations where these agencies should focus their research (e.g., Gulf of Mexico, east
coast OCS, or west coast OCS).238
EISs for offshore wind projects on the U.S. OCS may provide some insight into wind
development’s potential impacts on the marine ecosystem and its associated species, as well as
the alternative actions considered. EISs prepared by BOEM, with cooperating agencies, include
details about the potential marine ecosystem impacts of wind development. As the agencies
develop EISs for more offshore wind projects on the U.S. OCS, Congress may wish to consider
whether specific agencies or an interagency working group should use these studies to identify
emerging patterns of impacts to marine ecosystems in specific areas of the U.S. OCS.239 Such
assessments may also identify trends in the size of offshore wind development projects or
developments in the types of wind turbine foundations, among other patterns. (Also see the text
box “Department of Energy Wind Energy Research and Development and Impacts,” below).
If assessments identify patterns in offshore wind EISs, such findings could help inform
decisionmaking about the level of funding needed to implement mitigation strategies, for
example, or for restricting areas of the U.S. OCS that may not be suitable for offshore wind
development (e.g., based on water depth, seabed composition, or critical habitat). Alternatively, if
an analysis of EISs for offshore wind projects identifies no patterns, it could suggest that
generalizations from existing OWFs on the U.S. OCS (or from the North Sea) cannot be applied
to newly proposed lease sites for offshore wind. If so, the question of whether BOEM should
evaluate and consider each new proposal individually could be an issue for Congress.

238 For example, in the 118th Congress, H.Rept. 118-126 (accompanying H.R. 4394) includes support for DOE research
“related to resource characterization, site planning, aquaculture assessments, community outreach, and planning for
long term environmental monitoring for applications of marine energy and floating offshore wind technologies to
support sustainable, scalable aquaculture production.” S.Rept. 118-72 (accompanying S. 2443) includes support for
DOE research “[w]ithin available funds, up to $5,000,000 is recommended to support university-led research projects
related to resource characterization, site planning, aquaculture assessments, community outreach, and planning for
long-term environmental monitoring for applications of floating offshore wind and marine energy technologies to
support sustainable, scalable aquaculture production.” The Senate report continues with the following language: “The
Committee encourages the Department to continue to support research and development related to siting and
environmental permitting issues, which if not properly addressed may lead to unnecessary delays in achieving the
National goal to deploy 30 gigawatts of offshore wind generation by 2030. In considering research and development
funding related to siting and environmental permitting issues, the Department shall prioritize the development of
technologies and capabilities related to minimizing impacts to coastal communities, Federal radar missions, and living
marine resources. The Committee encourages the Department to continue focusing efforts with non-profit and
academic partners to conduct coastal atmospheric boundary layer characterization that will help optimize and inform
efforts of the Department of Interior’s Bureau of Ocean Energy Management and assist the growing domestic coast
wind energy industry.”
239 Scientists often conduct literature reviews to identify patterns in the results of similar studies published in peer-
reviewed journals (e.g., Galparsoro et al., “Reviewing the Ecological Impacts”; and Fatemeh Rezaei et al., “Towards
Understanding Environmental and Cumulative Impacts of Floating Wind Farms: Lessons Learned from the Fixed-
Bottom Offshore Wind Farms,” Ocean and Coastal Management, vol. 243 (2023)).
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Department of Energy (DOE)
Wind Energy Research and Development (R&D) and Impacts
Section 30003 of the Energy Act of 2020 (Division Z of the Consolidated Appropriations Act, 2021; P.L. 116-260,
42 U.S.C. §16237) authorized the Secretary of Energy “to establish a program to conduct research, development,
demonstration, and commercialization of wind energy technologies.” One of the program’s purposes is “to reduce
and mitigate potential negative impacts of wind energy technologies on human communities, the environment, or
commerce.” The section identifies several subject areas for research, development, demonstration, and
commercialization activities. Subjects relevant to offshore wind include fixed and floating substructure systems,
materials, and components; the operation of offshore facilities to (1) conduct research for oceanic, biological,
geological, and atmospheric resource characterization and (2) test development, demonstration, and
commercialization of large-scale and full-scale offshore wind energy support structure components and systems;
and monitoring and analysis of site and environmental considerations unique to offshore sites (including freshwater
environments). One subject area, reducing market barriers to the adoption of wind energy technologies, includes
impacts or challenges relating to local communities and wildlife and wildlife habitats. Another subject area is
technologies or strategies that “avoid, minimize, and offset the potential impacts of wind energy facilities on bird
species, bat species, marine wildlife, and other sensitive species and habitats.” According to DOE’s FY2024 Budget
Request, in FY2023, the Offshore Wind Environmental and Siting R&D subprogram was funded at $13,145,000.
For FY2024, the Administration requested $38,260,000 for this same subprogram.
Offshore Wind Development and Competing Ocean Uses
Some Members of Congress have expressed concern about how the development of offshore
wind energy on the U.S. OCS may compete or conflict with other uses of maritime space and
how such competition may affect the marine ecosystem and associated species.240 A House-
passed bill in the 118th Congress would require the GAO to “assess the sufficiency of the
environmental review processes for offshore wind projects,” with attention to impacts of
development on marine wildlife, commercial and recreational fishing, and military use of the
ocean, among other factors.241 Some favor legislation to limit U.S. OCS wind development to
facilitate existing ocean uses and reduce local and regional impacts of offshore wind
development;242 others focus on the potential environmental, social, and economic benefits that
may result from long-term reduction of CO2 emissions via renewable offshore energy.243
Offshore wind energy development could result in loss of fishing grounds, disruption to NMFS
surveys, incidental take of birds, and increased vessel activity.
Loss of Fishing Grounds. One concern of the U.S. fishing industry is that during the
construction of offshore wind projects, the USCG proposes to establish a temporary safety zone
of 500 meters around OWFs that excludes commercial and recreational fishing vessels.244
Limitations on fishing gear in and around offshore wind areas also may be considered a “loss of

240 See H.Res. 239 in the 118th Congress.
241 H.R. 1, §20118.
242 For example, see H.R. 4284 in the 118th Congress.
243 For example, see Galparsoro et al., “Reviewing the Ecological Impacts,” p. 5. Also see U.S. Representative Paul D.
Tonko, “Tonko Introduces Sweeping Offshore Wind Legislation,” press release, December 22, 2022,
https://tonko.house.gov/news/documentsingle.aspx?DocumentID=3776; and Center for American Progress, “The
Inflation Reduction Act Will Help Boost Offshore Wind Production,” https://www.americanprogress.org/article/the-
inflation-reduction-act-will-help-boost-offshore-wind-production/.
244 See U.S. Coast Guard, “Safety Zone; Vineyard Wind 1 Wind Farm Project Area, Outer Continental Shelf, Lease
OCS-A 0501, Offshore Massachusetts, Atlantic Ocean,” 88 Federal Register 27839, May 3, 2023. 33 C.F.R. Part 147
permits the establishment of safety zones for non-mineral energy resource permanent or temporary structures on the
OCS.
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grounds.”245 Changes in fishing practices and fisheries displacement could increase interactions
(e.g., entanglements with fishing gear) between marine mammals and the fishing industry in
OWF areas.246 Scenario modeling suggests additional fisheries management measures (e.g.,
modified catch quotas, spatial and temporal management areas) may need to occur both inside
and outside OWFs to avoid any unintended negative effects from redistributed fishing
activities.247
Some Members of Congress have suggested establishing a fund to compensate U.S. fishers
impacted by offshore wind activities.248 Such a fund could be similar to the Fishermen’s
Contingency Fund—a fund that compensates fishers for gear damaged from offshore oil and gas
infrastructure—or could address a broader range of potential impacts.249 In June 2022, BOEM
sought feedback on draft guidelines for offshore wind lessees to mitigate impacts of their
activities on commercial and recreational fisheries, including through financial compensation.250
Some offshore wind developers already have pursued financial compensation arrangements with
fishers in the development area.251 BOEM also has included financial compensation for the
fishing industry in the sale terms for some lease auctions. For example, in the final sale notice for
its August 2023 Gulf of Mexico wind lease sale, BOEM offered a 10% bidding credit to bidders
who commit to contribute to a fisheries compensatory mitigation fund “to mitigate potential
negative impacts to commercial and for-hire recreational fisheries.”252
Disruption to NMFS Surveys. One concern for NMFS, as well as for the U.S. fishing industry,
is potential interruptions to regular (e.g., seasonal or annual) fishery surveys during the
construction of offshore wind projects. NMFS and other researchers regularly operate surveys to
track the abundance and distribution of fish stocks over time.253 Surveys provide information on
fishery resources and their environment. The data derived from fishery surveys inform stock
assessments and management plans and actions. Delays or modifications to the scope or
geographic scale of surveys can impede the ability of NMFS, U.S. regional fishery management

245 NOAA, “Offshore Wind Energy: Fishing Community Impacts,” https://www.fisheries.noaa.gov/topic/offshore-
wind-energy/fishing-community-impacts.
246 Methratta et al., “Offshore Wind Development in the Northeast U.S. Shelf,” pp. 16-27.
247 Miriam Püts et al., “Trade-Offs Between Fisheries, Offshore Wind Farms and Marine Protected Areas in the
Southern North Sea: Winners, Losers and Effective Spatial Management,” Marine Policy, vol. 152 (2023), 105574, pp.
1-17; Methratta et al., “Offshore Wind Development in the Northeast U.S. Shelf.”
248 See, for example, Senator Ed Markey, “Senator Markey, Rep. Moulton Announce Bicameral Efforts on National
Offshore Wind and Fisheries Compensation,” press release, December 22, 2022, https://www.markey.senate.gov/news/
press-releases/senator-markey-rep-moulton-announce-bicameral-efforts-on-national-offshore-wind-and-fisheries-
compensation.
249 43 U.S.C. §1842.
250 BOEM, “Guidelines for Mitigating Impacts to Commercial and Recreational Fisheries on the Outer Continental
Shelf Pursuant to 30 C.F.R. Part 585,” June 23, 2022, https://www.boem.gov/sites/default/files/documents/renewable-
energy/DRAFT%20Fisheries%20Mitigation%20Guidance%2006232022_0.pdf. Also see BOEM, “Reducing or
Avoiding Impacts of Offshore Wind Energy on Fisheries,” https://www.boem.gov/renewable-energy/reducing-or-
avoiding-impacts-offshore-wind-energy-fisheries.
251 See, for example, Vineyard Wind and Massachusetts Executive Office of Energy and Environmental Affairs,
“Agreement Regarding the Establishment and Funding of the Massachusetts Fisheries Innovation Fund,” May 21,
2020, https://static1.squarespace.com/static/5a2eae32be42d64ed467f9d1/t/5ee122f4c0502b68b9dc41cf/
1591812875587/MA+Fisheries+Compensatory+Mitigation+Plan+-+May+2020.pdf; and Vineyard Wind, “Vineyard
Wind 1 Fisheries Compensatory Mitigation Program for the Offshore Export Cable Corridor,”
https://www.vineyardwind.com/cable-compensation-package.
252 BOEM, “Final Sale Notice for Commercial Leasing for Wind Power Development on the Outer Continental Shelf in
the Gulf of Mexico (GOMW-1),” 88 Federal Register 47173, July 21, 2023.
253 NOAA NMFS, “Research Surveys,” https://www.fisheries.noaa.gov/national/science-data/research-surveys.
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councils, and others to assess and manage stocks.254 Some stakeholders, as well as NOAA, have
expressed concerns about potential conflicts offshore wind construction and development may
pose for NMFS surveys.255
Incidental Take of Birds. Some stakeholders have raised concerns about OWFs’ impacts on bird
populations, especially ESA-listed species or non-listed species with small population sizes.256
Other stakeholders seek ways to reconcile prohibitions against killing certain birds with continued
action to promote renewable energy production.257 Some further contend that wind energy
developers would benefit from more consistent enforcement of the MBTA for unintentional
takings.258
In September 2021, FWS announced its objective to “create a common-sense approach to
regulating the incidental take of migratory birds that works to both conserve birds and provide
regulatory certainty to industry and stakeholders.”259 This FWS policy could be a subject of
congressional interest, including how it might affect BOEM’s anticipated approval of offshore
wind leases over the next five years.
FWS can authorize limited incidental or intentional take under the ESA or the MBTA. For
example, FWS has authorized industry-wide, programmatic incidental take for ESA-listed species
in relation to land-based wind energy development through Section 10 of the ESA.260 FWS also
can authorize take for species protected under the MBTA through permitting under an existing
regulatory process (50 C.F.R. §21.41). FWS can issue such permits to individuals or through
species-specific programs that grant permission to states or other public entities to issue permits
for take in certain contexts.261 In such cases, FWS balances stakeholder needs with a species’
population status as well as obligations under the MBTA and migratory bird treaties. Obligations
to these treaties may be of interest to Congress when considering amendments to the MBTA.

254 For more information on U.S. regional fishery management councils, see CRS Report R47645, U.S. Regional
Fishery Management Councils, by Anthony R. Marshak.
255 For example, the Research Offshore Development Alliance and Seafood Harvesters of America has expressed
concerns about offshore wind impacts on surveys, including in a letter to members of the House and Senate Commerce,
Justice, Science, and Related Agencies subcommittees of the Committees on Appropriations (Anastasia E. Lennon,
“Fishing Industry: Millions More Needed to Support NOAA Surveys amid Wind Development,” The New Bedford
Light, March 20, 2023, https://newbedfordlight.org/fishing-industry-millions-more-needed-to-support-noaa-surveys-in-
light-of-wind-development/); NOAA, “Efforts to Mitigate Impacts of Offshore Wind,” https://www.fisheries.noaa.gov/
feature-story/efforts-mitigate-impacts-offshore-wind-energy-development-noaa-fisheries-surveys.
256 For example, BOEM, “Transparent Modeling of Collision Risk for Three Federally-Listed Bird Species to Offshore
Wind Development (AT-21-x07),” August 2023, https://www.boem.gov/sites/default/files/documents/environment/
environmental-studies/Transparent%20modeling%20of%20collision%20risk%20for%20three%20federally-
listed%20bird%20species%20to%20offshore%20wind%20development_1.pdf.
257 White & Case, “Environmental Laws and Regulations Affecting U.S. Offshore Wind,” https://www.whitecase.com/
insight-our-thinking/environmental-laws-and-regulations-affecting-us-offshore-wind.
258 Erika Bosack, “Incidental Take Under the Migratory Bird Treaty Act and How to Share the Skies,” William & Mary
Environmental Law and Policy Review, vol. 46, no. 3 (2022), pp. 849-853 (hereinafter referred to as Bosack,
“Incidental Take Under MBTA”).
259 DOI, “Interior Department Ensures Migratory Bird Treaty Act Works for Birds and People,” press release,
September 29, 2021, https://www.doi.gov/pressreleases/interior-department-ensures-migratory-bird-treaty-act-works-
birds-and-people.
260 For example, incidental take permits under ESA Section 10 have been issued for activities related to renewable
energy development that, while otherwise legal, may result in take of lesser prairie chickens (e.g., 86 Federal Register
19634). For more information on lesser prairie chicken incidental take permits, see CRS Report R47632, Lesser Prairie
Chicken Listing Under the Endangered Species Act (ESA), by Pervaze A. Sheikh and Benjamin M. Barczewski.
261 For example, FWS has issued statewide depredation permits to protect commercial livestock producers from black
vulture depredation.
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FWS has not published permitting guidelines under the MBTA related to incidental take
associated with wind development.262 An option for Congress on this issue could be to direct
FWS to create exceptions to protections for certain species.263
Increased Vessel Activity. Some stakeholders have expressed concerns about increased vessel
activity in the areas of offshore wind development.264 The development of offshore wind areas
has been estimated to rely on at least 27 vessels per project across all the project stages.265
Increased vessel activity may pose navigation and safety concerns for fishers (and other maritime
industries), may displace fishers from their fishing grounds, and may increase the risk of whale
strikes both from OWF-associated vessels and potentially displaced vessels from other sectors.
An option for Congress on the issue could be to direct the USCG, the primary authority for
navigational safety in U.S. waters, to enhance communications and monitoring for vessel traffic
(including vessel speed and seasonal speed limits)266 in offshore lease areas.267 Another option for
Congress could be to provide direction to NMFS on vessel speed regulation potentially
considering risk tolerance, existing technology and other vessel strike avoidance measures, and
relevant spatial and temporal factors.268
The James M. Inhofe National Defense Authorization Act for Fiscal Year 2023 (Division J, Title
CXIII, Subtitle A of P.L. 117-263) directed several federal agencies to address the impacts of
vessel traffic on marine mammals through federal grant programs and real-time monitoring,
among other actions.269 In addition to these actions, Congress may wish to consider identifying
technological opportunities that would allow federal agencies (e.g., BOEM, DOT, NOAA, and
USCG) to analyze vessel activity in offshore wind energy areas, including vessel types, speed,
and vessel strike incidents with large marine mammals. The boundaries of offshore wind areas
could be incorporated into SeaVision, a maritime domain awareness sharing tool for the U.S.
government and partner governments developed by DOT (see the text box on “SeaVision,”
below). In considering proposed offshore wind areas, federal agencies and partners could use
SeaVision to analyze the activities of vessel types (e.g., fishing vessels, vessels associated with
OWF construction) as well as to identify patterns, if any, in the occurrence of vessel and marine
mammal interactions.

262 Bosack, “Incidental Take Under MBTA,” pp. 850-851.
263 Ibid.
264 Consensus Building Institute, Stakeholder Perspectives on the Development of a North Atlantic Right Whale Vessel
Risk Reduction Strategy, report prepared for BOEM, Office of Renewable Energy Programs, OCS Study, BOEM 2023-
004, 2023, https://www.boem.gov/sites/default/files/documents/renewable-energy/studies/
Stakeholder%20Perspectives%20of%20Vessel%20Risk%20Reduction%20and%20NARWS_0.pdf.
265 American Clean Power, “Offshore Wind Vessel Needs,” https://cleanpower.org/wp-content/uploads/2021/09/
Offshore-Wind-Vessel-Needs.FINAL_.2021.pdf. For additional discussion of OWF deployment and vessel issues, see
CRS Report R46970, U.S. Offshore Wind Energy Development: Overview and Issues for the 118th Congress, by Laura
B. Comay and Corrie E. Clark.
266 Seasonal vessel speed limits of 10 knots have been in place since 2008 to minimize vessel strike impacts to marine
mammals. NOAA NMFS, “Endangered Fish and Wildlife; Final Rule to Implement Speed Restrictions to Reduce the
Threat of Ship Collisions with North Atlantic Right Whales,” 73 Federal Register 60173-60191, October 10, 2008.
267 For example, some fishers identify safety and navigation concerns within an OWF as factors limiting their decision
to fish in the area (Angela Silva et al., “Fisheries Socioeconomics” in Fisheries and Offshore Wind Interactions:
Synthesis of Science, NOAA NMFS, NOAA Technical Memorandum NMFS-NE-291, March 2023,
https://repository.library.noaa.gov/view/noaa/49151).
268 For example, see NOAA NMFS, “Amendments to the North Atlantic Right Whale Vessel Strike Reduction Rule;
Extension of Public Comment Period,” 87 Federal Register 56925, September 16, 2022; and in the 118th Congress
H.Amdt. 566 to H.R. 4821 and S. 2986.
269 See §§11302-11304 of Division J, Title CXIII, Subtitle A, in P.L. 117-263.
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SeaVision
SeaVision is a web-based sharing network of maritime domain awareness information (i.e., the effective
understanding of anything associated with the maritime domain that could impact security, safety, the economy, or
the marine environment) developed by the U.S. Department of Transportation (DOT) and the U.S. Navy.a
SeaVision uses nonclassified vessel Automatic Identification System (AIS) data to display current and past vessel
movement within the U.S. exclusive economic zone (EEZ), the EEZs of partner countries, and on the high seas
(international waters) on a live SeaVision map.b AIS data include navigation information, such as the identity, flag
state, type, course, and speed of the vessel, that is transmitted in real-time via ship-to-ship or ship-to-shore
transmissions.c In general, information of vessels in EEZs is obtained via radio frequency data and information
about vessels on the high seas is obtained by satellite data.
SeaVision may be accessed and used by U.S. federal agencies with a maritime interest or by any partner country.d
According to DOT, as of October 2023, 63 foreign governments were participating in SeaVision through a
partnership with the U.S. government.e
SeaVision can be used to analyze individual vessel activity or the activity of vessels within a specific area of the
ocean.f For example, SeaVision can be used to analyze the tracks of a single cargo vessel or the activity of all fishing
vessels in the Gulf of Maine in real time or over a certain time period, among other scenarios. SeaVision data may
be analyzed to identify maritime security incidents, illegal fishing activity, vessel interactions (e.g., vessel-to-vessel
collision or vessel strike of marine mammal), areas of heavy vessel activity, vessel speed, and more.
Sources:
a. DOT, Volpe Center, “SeaVision,” https://info.seavision.volpe.dot.gov/.
b. Ibid.
c. U.S. Coast Guard, “Automatic Identification System (AIS) Overview,” https://www.navcen.uscg.gov/
automatic-identification-system-overview.
d. U.S. Navy, “SeaVision: Improving Maritime Domain Awareness During Cutlass Express,” press release, July
29, 2021, https://www.navy.mil/Press-Office/News-Stories/Article/2712219/seavision-improving-maritime-
domain-awareness-during-cutlass-express/.
e. Email communication between CRS and DOT, Volpe Center, October 27, 2023.
f.
U.S. Navy, “SeaVision: Improving Maritime Domain Awareness During Cutlass Express,” press release, July
29, 2021, https://www.navy.mil/Press-Office/News-Stories/Article/2712219/seavision-improving-maritime-
domain-awareness-during-cutlass-express/.

Author Information

Caitlin Keating-Bitonti, Coordinator
Corrie E. Clark
Analyst in Natural Resources Policy
Specialist in Energy Policy

Anthony R. Marshak
Erin H. Ward
Analyst in Natural Resources Policy
Coordinator of Research Planning

Laura B. Comay
Pervaze A. Sheikh
Specialist in Natural Resources Policy
Specialist in Natural Resources Policy

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Disclaimer
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Congressional Research Service
R47894 · VERSION 1 · NEW
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