Exploring the impact of offshore wind on whale deaths

Michael Stocker of Ocean Conservation Research will present his work Thursday, Nov. 21, as part of the virtual 187th Meeting of the Acoustical Society of America, running Nov. 18-22, 2024.

In pursuit of clean energy goals and to reduce atmospheric carbon emissions, developers are increasingly exploring building wind turbines in the waters off the East Coast of the United States. Three offshore wind farms are already in operation, with several more planned or underway. These wind farms stand to generate a significant amount of carbon-free electricity, which can help coastal states meet their decarbonization goals.

The increased presence of these turbines in coastal waters, along with the noise from construction and surveys, has led to concerns of their impact on marine life. In particular, cetaceans such as whales and dolphins are likely to be sensitive to the noises and increased marine traffic brought by these turbines.

However, the Marine Mammal Commission, a federal oversight agency, states there is no evidence linking the whales that died in the New Jersey region in the winter of 2022-2023 to wind energy development.

According to necropsies performed on recovered whales, many of them died from collisions with ships. The Marine Mammal Commission notes that this is not a particularly unusual occurrence, nor is the number of whale deaths in this period higher than average. A rise in ship strikes over the last decade is mostly due to a simple combination of more whales plus more ships.

"In the case of a lot of whales, population recoveries since the cessation of commercial whaling are coincident with increasing shipping traffic and increasing fishing efforts," said Stocker. "This is resulting in increased interactions between whales and the industrialization of the ocean."

Stocker, however, is concerned that the increased presence of survey ships in and around New Jersey waters may have exacerbated this issue.

"Were the ship strikes just a coincidence?" asked Stocker. "Or were they a product of compromised whale vigilance due to aggregated stress factors?"

Survey ships are employed by wind farm developers to map the seafloor in preparation for construction. These ships use underwater acoustic devices in their efforts, which can stress marine mammals such as whales. While one survey ship likely has little effect, Stocker highlights that 11 different surveys were operating in the region from December 2022 to March 2023, and that the cumulative impact of these surveys has not been properly evaluated.

Stocker hopes his Thursday session will spark a discussion among attendees with the goal of identifying approaches to minimize whale deaths in the future.