Fishermen in the Bering Sea black cod fishery, off the US state of Alaska, say an increase in orcas picking off their catch is getting so bad, some are foregoing the season altogether.

That's according to KUCB, in Unalaska, Alaska, where the commercial fishing hub of Dutch Harbor is located. The public radio station reports that the uptick in behavior is puzzling to biologists, too.

The behavior has been witnessed by crews on both large and small boats, including around trawlers, as the orcas, which are also known as killer whales, scavenge for fish that may drag from the back of the vessel, according to scientists.

The interactions can also be dangerous for the whales, with nearly a dozen orcas killed after encounters with fishing gear last year.

Some smaller vessels that target black cod have been switching to pot gear, as opposed to more traditional longlining, to prevent orcas from picking off their catch. However, other harvesters say the time and hassle isn't worth the cost, not at least this season.