Is Offshore Wind Surveying Causing Whale Deaths? A Biologist Explains

Two weeks ago, a 25-foot humpback whale washed ashore, dead, in Long Beach Township, New Jersey.

The harrowing sight of the whale–tumbling around, lifeless–on the water’s edge can no longer be counted as a rare occurrence. This was the third whale in the span of seven months to wash ashore in the small, south Jersey island community. Similar events have been recorded up and down the East Coast.

In 2023 alone, at least 13 humpback whales have been stranded on New Jersey or New York beaches, according to NOAA. Thirty-one dead humpbacks have been found in Virginia from 2016-2023. All told, more than 200 humpback whales have washed ashore, critically injured or dead, from 2016-2023 on East Coast beaches.

And it’s not just humpback whales that are suffering–minke whales, sperm whales and right whales have also faced similar fates.

What’s responsible for the spate of whale deaths? Various theories abound. One popular theory has to do with acoustic offshore wind surveying that is happening in the same area. The theory has picked up steam so much so that various legislators have called for a moratorium on surveying activities until the cause of the whale deaths is figured out.

And, while there’s no definitive evidence linking wind turbine surveying activity with whale deaths, here’s what science can tell us about the possibility of such a connection.

Human Produced Sound Can Imperil Underwater Wildlife

Marine creatures inhabit an environment conducive to acoustic interaction–with sound traveling nearly five times faster in water than in air. As a result, many underwater species rely on sound for navigation, communication, locating food and asserting territorial boundaries.

So, when humans produce “noise pollution” in the ocean–due to anything from driving a boat to surveying for oil and gas–there is always the possibility that marine wildlife might be affected. Here are a few studies that speak to some of these possibilities:

• A 2004 study examined the possible connection between humpback whale deaths and 3D seismic surveys taking place off the Brazilian coast. The researchers concluded that the “surveys were coincident with an unusual increase in the strandings rate of adult humpback whales in this region.” The authors also noted that the surveying was being conducted in an area known to be a breeding hotspot for humpback whales and, to make matters worse, during breeding season.
• Pulses from airguns, which are one of the methods surveyors use to figure out what might be on the ocean floor, and beneath it, can have negative impacts on mammals. For instance, an article published in the Marine Technology Society Journal states that acoustic blasts can cause tissue damage in the ears of marine mammals, though they say it’s more likely that such tissue damage would occur as a result of an underwater explosion, not from the airguns used in seismic surveying. Human divers, when exposed to pulses from airguns, have reported resonance of the lungs and short-term symptoms of dizziness, nausea and visual disruption.
• Seismic surveying can also cause large-scale displacement of marine mammal groups. One study found extended displacement of fin whales by a seismic survey which lasted well beyond the length of the survey. The noise produced by seismic surveying can also disrupt the communication of whales with each other. A 2007 study by the International Whaling Community found that around 250 male fin whales stopped singing for several weeks in an area where seismic surveying was taking place, and then resumed singing after. This is important because it is believed that song is an integral part of whales’ reproductive function, helping them find and attract mates.

Still, It’s Unlikely That Offshore Wind Surveying Is Causing The Whale Deaths. Here’s Why.

The type of surveying that is most perilous to marine mammals is seismic surveying. This is where special vessels equipped with powerful airguns produce pulses of air—generating sound waves—that are used to measure aspects of the seabed. This technique is common in oil and gas exploration, as the deposits surveyors are looking for are often buried deep beneath the seabed and the airgun pulses are loud enough to penetrate hundreds of miles into the ocean floor.

However, according to the Bureau of Ocean Energy Management (BOEM), airguns are not being used to survey the ocean floor in the proposed wind farm sites, as the surveyors are primarily interested in what’s on the seabed, not what’s beneath it. Instead, BOEM reports the use of a less invasive suite of acoustic techniques. In a recent report, they write:

“Deep penetration seismic airgun surveys are not used for offshore wind energy projects. [...] The offshore wind industry typically uses High Resolution Geophysical (HRG) surveys to assist with their siting efforts. HRG surveys use a suite of active sound sources to produce sounds that are reflected off subsea structures to obtain images of the seafloor and shallow geophysical features.”

High resolution geophysical surveys are unlikely to imperil cetaceans and other marine life, according to their report.

“BOEM and the NOAA Fisheries have assessed the potential effects of HRG surveys associated with offshore wind development in the Atlantic. Following a rigorous assessment, NOAA Fisheries and BOEM have concluded that these types of surveys are not likely to injure whales or other endangered species.”

This is not to say that offshore wind surveying couldn’t theoretically have some detrimental effect on cetacean life, but it’s less likely than may be commonly believed.