Bristol Bay red king crab move farther west in warmer years, satellite study finds

Mature male red king crab in Bristol Bay move farther west in years with warmer bottom water, according to a satellite tagging study NOAA Fisheries highlighted this week.

That matters because the areas closed to protect the crab don't move. Managers drew fixed closure areas after the Bristol Bay fishery collapsed in the early 1980s, NOAA says, and shifting crab may limit how well those areas work. One is the Red King Crab Savings Area, a block of Bristol Bay closed to bottom trawling since the mid-1990s.

Researchers attached pop-up satellite tags to crab during NOAA's eastern Bering Sea bottom trawl surveys from 2021 to 2024. The tags were set to release and float to the surface Oct. 11-15, just before the commercial fishery's usual Oct. 15 opening.

By fall, the crab generally moved west or southwest, into deeper, cooler water in central Bristol Bay, the researchers' models predicted. When they compared those predictions with the fall fishery's catches, "they generally aligned," said lead author Sean Hardison, a University of Alaska Fairbanks research associate.

"Our findings suggest that dynamic, rather than static, spatial closure boundaries may be more effective for red king crab," said co-author Erin Fedewa, a NOAA Fisheries biologist. Hardison said the results "don't prescribe new closure boundaries" but can help test proposed changes.

The idea is already being tried. The North Pacific Fishery Management Council has asked the Bering Sea pollock fleet to repeat its voluntary, shifting crab closures in and around the savings area during the 2027 pollock A season. In the first year, the inshore fleet reported 25 red king crab caught inside the savings area and its subarea.

The fishery has been shut down twice, in 1994-95 and for the 2021-22 and 2022-23 seasons. NOAA says warmer years and marine heat waves are becoming more common. Researchers are now tagging both male and female crab in winter and spring, when the crab mate and molt and are most vulnerable.