Experts: Vessel strikes, not wind farms, cause of whale strandings

Offshore wind forum brings together wildlife, policy, development leaders
April 18, 2023

Responsible wind farm development can be designed to mitigate effects on marine mammals while providing clean energy, according to a forum of experts in wildlife and offshore wind.

A panel comprising Kris Ohleth, Special Initiative on Offshore Wind executive director; Amber Hewett, National Wildlife Federation director of offshore wind energy; and Mike Dunmyer, US Wind Delaware development manager, met at the Rehoboth Beach Public Library April 12 to discuss concerns and approaches to offshore wind development.

Offshore wind jumped off the map as a large-scale climate solution the National Wildlife Federation can get behind, Hewett said. While an abundance of offshore land is available, she said, development could potentially have detrimental impacts on wildlife if not done right.

“Our support for offshore wind comes with a whole lot of conditions, and our list of conditions is only growing,” she said. 

Responsible development must be rooted in science, mitigate impacts on wildlife and reduce negative impacts on other ocean uses, she said. It must include consultation with Native American tribes, state and local governments, community stakeholders and underserved communities.

“These are standards that we really don’t compromise on,” she said. “We have intervened, litigated against an offshore wind project that didn't meet our standards. I hope that we never have to do that again.” 

Right now, she said, just seven offshore wind turbines are running in U.S. waters – two off Virginia and five off Block Island, R.I. Gas pipelines and the burning of gas are worse for wildlife, she said, so it’s best to make offshore wind the best choice it can be.

The impacts of underwater noise on wildlife are most concerning, Hewett said, particularly during the construction phase when pile-driving and increased vessel traffic occur. 

Vessel strikes are among the leading causes of death for marine mammals, she said. As 40% of offshore vessels are oil- and gas-related, she said, shifting to electric will ultimately require fewer sea vessels transporting oil and gas. Collisions with birds and bats are also a concern, she said.

To address those issues, she said the National Wildlife Federation defines best practices and recommendations, including reduced vessel speed limits, times of day and year for construction pile-driving, and noise mitigation technology to absorb underwater sounds of construction.

Wind farm development occurs with a small number of vessels and a high level of regulation, Ohleth said, including eyes on the water via trained, sanctioned observers looking for wildlife.

The northeast coast is favorable for development due to high offshore wind speeds, an increased demand for electricity in the region, and a sloping offshore topography that creates great conditions on which to build, she said. 

Directly off the East Coast, there are thousands of vessels in a year's time, but only two or three are being used in offshore wind development. 

Sounds produced during surveys are under 210 decibels, can be focused on a certain area, and are short pulses with long amounts of silence in between, she said. They are quieter than sounds produced during oil and gas surveys because they penetrate only a couple hundred feet, while oil and gas surveys can go thousands of meters below the sea floor.

All activities have to be approved and mitigation methods met, she said, including NOAA requirements for the regulation and protection of marine mammals through an Incidental Harassment Authorization.

“Through this IHA process, no marine mammals are ever authorized to be harmed or killed. Period. Full stop. That is an absolute fact. 100%,” she said. “So that is not legal, it's not authorized, there is no type of impact to marine mammals from offshore wind surveys authorized in that way.”

Dunmyer said his company has rights to an 80,000-acre lease area from Fenwick Island south along the Maryland coast. The company can develop up to 1,100 megawatts of offshore wind, enough to power 340,000 area homes with 76 turbines and three offshore substations, he said. 

Surveys include taking core samples of soil from the sea floor, which makes very little sound, and geophysical surveys to map the sea floor that do produce sound, he said.

“Whale strandings that we’re seeing this year are not related to offshore wind development activities,” he said. “While all these strandings are tragic and incredibly sad, these are charismatic creatures that we care very much about, but it is unfortunately not unique.”

This year, 15 whale strandings occurred, he said; in previous years there have been far more, including 52 on the East Coast in 2007. Every federal organization with expertise in this area stated that offshore wind development activities are not causing whale strandings, Dunmyer said; the main causes are ship strikes or gear entanglements.

Offshore wind surveys do not use seismic air guns that are used in oil and gas surveys, he said. Most gear used produces sound at a frequency outside what large whales pick up on, he said. Two types of gear do produce sounds large whales can pick up at the source of the sound, he said, and they dissipate quickly.

NOAA-trained and certified protected species observers accompany the survey ship to set up and monitor a 500-meter exclusion zone for right whales and a 100-meter exclusion zone for all other whales, he said.

Observers use visual and acoustic technology to certify no marine mammals are in the exclusion zone, he said. If a whale enters the zone, work shuts down until the animal has exited the area, he said. This has happened three times during a year of surveys completed by US Wind, he said.

To reduce construction noise, Dunmyer said pile-driving is done from May to November, when large whales are least likely to be in the area. Sound-attenuating technology such as physical sheaths around the pile driving apparatus and double-bubble curtains are used, he said. One piling is installed a day to ease stress on the environment, he said. 

During a submitted question-and-answer period, Dunmyer said migratory birds travel to the west of US Wind-leased areas, and most other marine birds fly close to the ocean, beneath turbine blades, because they are hunting. With no other visual obstruction, he said, they can see wind farms from miles away. 

A man interrupted Dunmyer several times during his responses and stated that chemicals from wind farms will flow up the Delaware Bay and spread pollution. Dunmyer said that wind farms transmit electricity, not chemicals, and that chemicals are not used in pile driving; the man said chemicals are present in the concrete.

During the interruptions, various audience members told the man to let Dunmyer speak. One man exited the room during the outbursts, saying he had heard enough.

When asked what was the acceptable number of dead marine animals, Hewitt replied: none. 

The National Wildlife Federation does not endorse anything that endangers animals, she said, and no offshore wind project has been permitted to harm or kill a marine animal. Temporary disturbances that will not harm or kill come with development, she said, and no animal would be accepted as collateral damage.

The presentation was hosted by People for Offshore Wind Energy Resources Delaware, sponsored by Energize Delaware and moderated by Marc Weiss, CEO of Global Urban Development.


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