October 2, 2023 — An unusually high number of whales have died in trawl fishing gear in Alaska waters, spurring a federal investigation and new criticism of the industry that uses big nets to scoop fish from the bottom of the ocean.
Ten killer whales, also known as orcas, were ensnared in trawl gear this year in the Bering Sea and along the Aleutian Islands, and nine of them died, according to the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service. The toll compares to six killer whale deaths in Alaska fisheries documented over the five years spanning from 2016 to 2020, according to NOAA Fisheries records.
While pollock makes up the biggest volume of fish harvested in the Bering Sea and Aleutians, all of the trawlers involved in this year’s killer whale deaths were harvesting different types of groundfish. Those vessels, participants in what NOAA Fisheries classifies as the Amendment 80 trawl fishery, harvest yellowfin sole, Pacific ocean perch and other bottom-dwelling species.
Critics of bottom trawling speculate that the whales are dying after chasing fish discarded as bycatch by the vessels. Bycatch is the incidental harvest of non-targeted species.
It is possible that climate change has disrupted normal food supplies, said Jon Warrenchuk, a senior scientist with the environmental group Oceana.
“The food web is so out of whack in the Bering Sea and Gulf of Alaska,” Warrenchuk said.
That means that orcas are turning to the food they find around trawl ships, he said. “The whales now have been conditioned to be feeding off the discards of the factory trawlers,” he said.
Halibut may be a particularly fatal attraction for the whales, Warrenchuk said.
He cited a relatively new practice called “halibut deck sorting,” which is allowed exclusively for the non-pollock Amendment 80 trawlers through a rule enacted in 2019.
The practice, a response to reduced halibut stocks, is intended to reduce impacts of halibut bycatch. Under the rule, trawlers within a particular fleet are allowed to send incidentally caught halibut back into the sea without penalty as long as certain requirements are met. The halibut must be alive, they must be returned to the water within 35 minutes and the entire process must be monitored by an onboard fisheries observer, according to the rule.