A federal investigation into the unusually large number of Bering Sea and Aleutian killer whales found dead this summer determined that most but not all of the deaths were killed by entanglement in fishing gear.
The National Oceanic and Atmospheric Administration’s Alaska Fisheries Science Center on Friday released some details about the deaths in the Bering Sea and Aleutians, which had spurred sharp criticism of seafood trawling practices.
Of the nine killer whales that were found ensnared in bottom-trawling gear, six were killed by those entanglements but two others were already dead before they were netted, the investigation found. The other whale was seriously injured by the gear entanglement but escaped alive, the agency said.
In addition to the nine whales found in bottom-trawl gear, there were two other cases of dead killer whales found entangled in other types of fishing gear.
The bottom-trawling gear that entangled the nine whales, also called orcas, was from vessels in what is known as the Amendment 80 fleet – roughly 20 large ships that both catch and process fish. These catcher-processors use trawl nets that sweep the seafloor to harvest Atka mackerel, yellowfin sole, rock sole and other flatfish species. They do not harvest pollock, the species that makes up the biggest volume of harvested Alaska seafood.
In the other two cases, one dead killer whale was found in trawl gear used by a vessel harvesting pollock, the agency said. That whale was determined to have been dead before it became entangled.
Alaska’s pollock harvesters do not use bottom-trawl gear; instead, their nets scoop fish in waters that are more in the middle range of the ocean depths.
The 11th case was a whale found dead in longline gear used by a NOAA Fisheries vessel to conduct an annual survey for sablefish and groundfish. It was the first killer whale death in the 30 years that NOAA Fisheries has been conducting the survey, the agency said.
Genetic analysis of samples that were collected from eight of the whales revealed that all were members of the Eastern North Pacific resident stock, the most plentiful of Alaska’s killer whale stocks. All were female, the agency said.
While the total number of dead killer whales was much higher than past years’ totals but not high enough to cause negative population effects, the investigation found.
“Given the high level of incidental catches of killer whales in 2023, we knew it was important to move as quickly as possible to better understand whether these incidental takes pose a conservation concern to any of the potentially affected killer whale stocks,” said Robert Foy, director, Alaska Fisheries Science Center. For that reason, the center expedited the genetic analysis to better understand potential impacts on Alaska’s different killer whale populations.
To Jon Warrenchuk, a senior scientist with the environmental group Oceana, the results raise some additional questions. He said killer whale deaths have been increasing in trawl fisheries.
“We’re well past the point for taking a hard look at the impacts of bottom trawling in Alaska,” Warrenchuk said.
And he noted that the flatfish being harvested by the ships involved in the deaths are generally lower-priced and of lower value. “The fact that it happened during the harvest of this low-value fish brings into question whether the value of that fishery is even worth the cost of killing all these whales,” he said.
Warrenchuk said it is possible that the trawlers involved in the whale entanglements were targeting sablefish, a more valuable species than the flatfish that make up the bulk of the vessels’ harvests. Amendment 80 vessels in past years were prohibited from targeting sablefish, but that has changed recently, and they now have quota rights to some of those higher-value fish, he noted.
Oceana has asked for more information about the specific locations and time of the whale incidents
Critics of Bering Sea trawling practices have said the killer whale deaths might be attributable to the discards of fish netted incidentally as bycatch. The whales have identified the trawlers as a source of food, the critics argue.
In particular, they have pointed to a practice known as “halibut deck sorting,” in which the Amendment 80 trawl vessels are allowed to return incidentally caught halibut to the sea without it counting against their bycatch limits as long as the fish are sent back to the ocean within 35 minutes and in good shape. However, a recent report submitted to the North Pacific Fishery Management Council shows a significant reduction since 2020 in observed incidences of killer whales feeding off Amendment 80 trawler discards.
There are other concerns about halibut bycatch by the Amendment 80 fleet. Last week, NOAA Fisheries enacted a new rule that could reduce the fleet’s halibut bycatch cap. The rule replaces the current fixed limit of 1,745 metric tons with one that can be reduced as much as 35% below that if halibut populations are low.
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