Over the past three decades, 35 killer whales were entangled in fishing gear in Alaska, resulting in 25 deaths, according to a 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 the unusually high number of 2023 cases, in which an additional 10 killer whales were found ensnared in fishing gear — mostly bottom-trawl gear — with nine of them found dead.
That raises the total caught in gear since 1991 to 45 killer whales, with 34 dead.
The high 2023 numbers sparked a special examination by the agency.
The cases documented in the report from 1991 to 2022 involved a variety of fishing gear. Trawl gear caused 20 of the entanglements, longline gear caused 10 of them and assorted other gear was implicated in other cases.
Killer whales, also known as orcas, are found in oceans around the world but generally favor colder waters. Several populations of killer whales swim in Alaska waters; some eat fish exclusively and some feed on hunted marine mammals. They are among the marine mammals that are occasionally killed by human activities in marine areas.
Killer whales are known to follow vessels to feed on the fish caught by net, hook, pot or trap, sometimes at their peril. Some die from asphyxiation because they become pinned in place underwater, and even if they escape alive, some wind up with serious injuries that could result in death later, the report said.
But there are gear modifications and devices that have the potential for reducing harm to the whales, the report notes. Barrier ropes that prevent whales from swimming into nets, sleeves that cover hooked fish being pulled up on longline gear, acoustic instruments that ward off whales and other devices should be further studied to see if they can effectively reduce the toll on killer whales, the report said.
In addition to the 35 reported entanglements over the three-decade period that involved fishing or marine gear, two other whales were determined to have been enmeshed in strings of kelp. Those determinations were based on analysis of photographs — demonstrating the importance of collecting photo evidence, the report said.
Killer whales and other whales are known to interact with kelp and have been observed playing with it. There is also evidence that rubbing against kelp soothes whales’ skin. It is likely that there were many more kelp entanglement cases than the two that were documented, the report said.
The affinity for kelp is a signal of a potential future problem as kelp and seaweed farming proliferates, the report noted. “Killer whales have the potential to interact with kelp farms’ anthropogenic material as well as crops,” it said.
Alaska killer whales are classified by stock and by prey type. Resident whales are fish-eaters, while transient whales hunt marine mammals. Multiple stocks are found in Alaska waters.
NOAA Fisheries estimates that there are 1,920 killer whales 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.
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