Report details of 37 known killer whales linked to Alaska over three decades

By means of Yereth Rosen, Alaska Beacon

Updated: 19 hours ago Published: 20 hours ago

Over the past three decades, 37 killer whales have been entangled in fishing gear in Alaska, resulting in 25 deaths, according to a new report issued by the National Oceanic and Atmospheric Administration.

The report from NOAA Fisheries covers documented cases from 1991 to 2022. It does not include this year’s unusually high number of cases, where 10 killer whales were found entangled. of fishing gear mostly under trawl gear where nine of them were found dead. Those events sparked a special investigation by the agency.

Cases documented from 1991 to 2022 involved a variety of fishing gear. Trawl gear caused 20 entanglements, longline gear caused 10 of them and various gears were involved in the other cases.

Killer whales, also known as orcas, are found in oceans around the world but usually prefer cooler waters. Large populations of killer whales swim in Alaskan waters; some eat fish exclusively and others eat hunted marine mammals. They are among the marine mammals that are sometimes killed by human activities in marine areas.

[NOAA Fisheries releases more information about high level of killer whales caught this year by Alaska trawl fleet]

Killer whales are known to follow ships to eat fish caught by net, hook, pot or trap, sometimes at their peril. Some die of asphyxiation because they are trapped underwater, and even if they escape alive, others have serious injuries that can lead to death later, the report said.

But there are changes in gear and tools that have the potential to reduce harm to whales, the report says. Barrier ropes that prevent whales from swimming into nets, sleeves that cover fish pulled by long lines, acoustic instruments that prevent whales and other devices must be tun to see if they can effectively reduce the number of killer whales, the report said. said.

Not all of the 37 reported incidents over a three-decade period involved fishing or marine equipment of any kind.

In two of the reported cases, the whales were determined to be entangled in kelp strings. Those determinations were based on an analysis of photographs that showed the importance of collecting photographic evidence, the report said.

Killer whales and other cetaceans are known to associate with kelp and have been observed playing with it. There is also evidence that rubbing kelp soothes the skin of whales. There are likely many more cases of kelp entanglement than the two documented, the report said.

The link to kelp is a sign of a potential problem in the future as kelp and seaweed farming increases, the report said. Killer whales have the potential to interact with kelp farms anthropogenic material as well as plants, it said.

Alaska killer whales are classified by stock and type of prey. Resident whales are fish eaters, while transient whales hunt marine mammals. Many stocks can be found in Alaskan waters.

NOAA Fisheries scientists were able to identify the stocks of 12 of the stranded whales through genetic testing. Nine are from the larger Eastern North Pacific Alaska Resident stock, and the other three are from the Eastern North Pacific, Gulf of Alaska, Aleutian Islands and Bering Sea Transient stocks.

NOAA Fisheries estimates that there are 1,920 animals in the Eastern North Pacific Alaska Resident stock, which swims in the Gulf of Alaska and Bering Sea, and 587 in the Eastern North Pacific, Gulf of Alaska, Aleutians Island and Bering Sea transient stock. Previous analysis by NOAA Fisheries found that the Eastern North Pacific Alaska Resident stock could withstand a loss of 19 animals a year, while the smaller transient stock could withstand a loss averaging 5.9 animals per year.

Originally published in Alaska Beaconis an independent, nonpartisan news organization covering Alaska state government.


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