Study Finds That Offshore Pile Driving Noise Alters Feeding Behaviors of Longfin Squid
Woods Hole Oceanographic Institution | via Phys.org | March 22, 2021
With the offshore wind industry expanding in the United States and elsewhere, a new study raises questions about how the noise from impact pile driving to install turbine supports can affect feeding behaviors of longfin squid, a commercially and ecologically important cephalopod.
Longfin squid (Doryteuthis pealeii), whose habitat stretches among continental shelf waters from Newfoundland to the Gulf of Venezuela, are most abundant in waters off the Northeast U.S. coast, where offshore wind farms are planned for the 2020s and 2030s within 18 lease areas.
Since 2010, longfin squid landings annually have amounted to about 11,000 metric tons and a value of $30 million, according to the U.S. National Marine Fisheries Service. Longfin squid also are important ecologically as a link between top predators and smaller fish and invertebrates.
The study found that when squid in an experimental tank were exposed to audio recordings of pile driving, they were less likely to capture prey during the noise playback and are more likely to abandon pursuing prey, if the noise started during their hunt. Because the squid have a high metabolic rate and need to feed frequently, “if cessation of feeding during noise leads to longer-term reduced food intake, then the potential exists for population-level reductions in squid abundance,” according to the researchers.
Pile driving involves repeated hammer strikes about every two seconds, to drive piles into the seabed and create support foundations for offshore development. The volume of underwater pile driving can exceed 200 decibels over a range of several hundred meters and the pitch of the noise can span frequencies from less than 100 Hz to over 10,000 Hz that can propagate for more than 10 kilometers.
I’ve heard that 100 decibels is like a rock concert, and that it can cause hearing loss in humans. I also heard — while I’m still able to — that the Occupational Health and Safety Administration (OSHA) recommends that people should spend less than fifteen minutes in a place where decibel levels exceed eighty decibels. to avoid hearing loss and damage.
… the noise diverted squid attention from a feeding task toward predator defense.
The press conference was unfortunately halted, due to overwhelming noise from a pile-driver’s convention in the next dining room, celebrating a 20-year contract to install offshore windfarms.
