Six killer whales caught in trawl net gear this year in waters off Alaska died as a result of their entanglement, while a seventh whale was seriously injured by this gear, according to a NOAA Fisheries statement released Friday.
Bering Sea trawlers this year also encountered three other killer whales, which NOAA Fisheries determined had died prior to making contact with the nets of these fishing vessels.
The trawl fishing industry’s 2023 take of killer whales, first made by public NOAA Fisheries in September, is significantly higher than in recent years past, according to a review of NOAA Fisheries death tolls through 2021.
The NOAA Fisheries statement Friday also reported that an 11th whale died this year as it became entangled in longline gear deployed by a vessel contracted by the agency to conduct a federal fishery survey.
[Trawl catch of killer whales brings new scrutiny to federal science behind Alaska take levels]
“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,” Robert Foy, director of the Alaska Fisheries Science Center, said in a written statement. “As a result, we expedited processing and some procedures …”
NOAA Fisheries was able to obtain genetic samples from eight of the killer whales. Tests indicated that they all were Eastern North Pacific Alaska residents that feed on fish, which are more abundant than a separate population of transient whales that feed largely on marine mammals.
These resident killer whales were found to all be females.
This year’s Bering Sea killer whale death toll has given new ammunition to critics of the trawl fleet, who have long raised concerns about the impacts of the vessel’s incidental take of a wide range of marine life.
“This is another tragic example of the problems with bottom trawling,” said Jon Warrenchuk, a senior scientist and campaign manager with Oceana, which submitted public records requests to gain additional information — including photos — of killer whale deaths in Alaska fisheries.
Bering Sea killer whales are not listed under the Endangered Species Act but are protected under the Marine Mammal Protection Act. NOAA estimates that — at a minimum — more than 1,900 of the resident killer whales reside in the Gulf of Alaska and Bering Sea.
In a finding required by the Marine Mammal Protection Act, the agency has determined that up to 19 of the Eastern North Pacific Alaska resident whales can die each year due to entanglements or other accidents involving humans without impacting the overall stocks.
That annual take number has received lots of scrutiny.
Some scientists say it’s based on an outdated assessment that sets the threshold too high. The case for revising the threshold number — known as the potential biological removal — was first made a decade ago in a study led by Kim Parsons, a NOAA Fisheries researcher, who found strong evidence of genetically distinct subpopulations of resident killer whales that prey largely on marine mammals.
A federal move to reclassify them into smaller groups would need a formal reassessment of stock structures that looks more closely at their range, diet and other information. An Alaska scientific review group has repeatedly recommended that a study be done, according to Craig Matkin, a former member of that group who said he quit in frustration when that failed to happen.
In October, the Center for Biological Diversity filed a 60-day notice of intent to sue the federal government for failing to protect killer whales and other marine mammals from being killed in the trawl fisheries.
The take of marine mammals by the trawl fisheries is tracked through the years by NOAA Fisheries. From 2017 to 2021, seven killer whales were seriously injured or died in the Bering Sea fisheries, including a female killed in 2021 in a trawl net as another whale — believed to be its calf — was released alive, according to the agency.
So far, the information released for 2023 does not give any detailed incident reports or locations where trawlers encountered the whales. But the most recent statement does offer more information about the fishing gear that encountered the whales.
One whale carcass was taken by a boat using large trawl nets used to catch pollock. NOAA Fisheries determined this whale was not killed by the trawl gear. It died prior to being caught, said the statement released by NOAA Fisheries.
[A struggle to dodge salmon in pursuit of a massive pollock bounty]
Nine of the whales were taken by another type of trawl vessel that tows nets along the bottom to largely target flatfish. Six of those killer whales died from the entanglements, one was seriously injured but alive when released and two were already dead prior to contact with this gear, according to NOAA Fisheries.
In October testimony to the North Pacific Fishery Management Council, an industry official said killer whales have been encountered in a Bering Sea bottom trawl fishery known as the deep-water flats.
John Gauvin, fisheries science director for the Alaska Seafood Cooperative, told the council that vessels involved in this fishery started having increased interactions with killer whales in 2020, and that all the whale entanglements this year involved this fishery.
“We want to conduct our fisheries without harming orcas and we’re taking steps to avoid future mortalities,” Gauvin said in his October testimony.
The deep-water flats fisheries unfold at depths often of more than 1,000 feet in a zone where the continental shelf gives way to the slope. It yields harvests of turbot and arrowtooth flounder as well as black cod.
In an earlier interview, Gauvin said that the whales are feeding in front of the nets. And, one vessel skipper this year set out a kind of water kite that covered part of the net opening. The kite did not appear to impede fishing, but more study is needed to determine how effective it could be in keeping whales out of the net.
Other options under consideration include a widely spaced rope barrier at the mouth of the net or an excluder device that would lead a whale to an escape portal, according to a research proposal.
In Friday’s statement, NOAA Fisheries said agency officials will “continue to work with the industry and our own survey operations teams to explore ways to reduce killer whale interactions.”
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Journalist Hal Bernton has covered Alaska fisheries issues extensively. He was a longtime reporter for The Seattle Times, and previously reported for the Anchorage Daily News and The Oregonian. Reach him at firstname.lastname@example.org.