Fishing crews across a broad expanse of the world’s oceans, ranging from the South Atlantic to the North Pacific, report unwelcome encounters with whales.
The fishing grounds off Alaska are a hot spot, a sometimes uneasy mixing zone for commercial fleets that collectively produce the United States’ largest seafood harvests, and whales that also depend on this bounty.
Alaska orcas, as well as endangered sperm whales, have for decades stripped the oil-rich black cod (also known as sablefish) off longlines.
Both orcas and sperm whales also relish Pacific halibut, a big, meaty flatfish. And in the Bering Sea, in recent years, some orcas have started to target the livers of Pacific cod.
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Surveys of fish-eating orcas estimate — at a minimum — almost 1,000 whales roam the Bering Sea, and more than 900 dwell in the Gulf of Alaska, according to the National Oceanic and Atmospheric Administration Fisheries. They are divided into numerous pods, and are far more plentiful than the 74 endangered southern resident orcas that frequent Puget Sound in three pods.
Alaska fishers have tried many, often unsuccessful, tactics to try to shake off whales [...]
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Off Alaska, the whale predation has been severe enough to prompt some fishers to give up the use of vulnerable longlines. Under federal rule changes in the Bering Sea — and later the Gulf of Alaska — they were able to switch to baited traps known as pots that can be set along the sea bottom to efficiently catch black cod.
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But the pots do not efficiently catch the much larger halibut.
And in recent years, the Unalaska-area orca pod learned how to tear into the slinky pot mesh to dine on black cod. Other whale pods also have started to breach the slinky pots. This raises the possibility that the Unalaska pod acts as a kind of innovation hub, developing new tactics, then spreading them to other pods.
From the article:
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