Mature Snow Crab Struggling in Eastern Bering Sea, But Immature Numbers Rising


A grasping pair of snow crabs. File photo via NOAA Fisheries.

A NOAA Fisheries analysis of the summer survey of Bering Sea crab stocks has concluded that in the wake of consecutive years of record warm temperatures numbers of mature male and female snow crab are still down, but there’s a significant increase in immature snow crab abundance, NOAA revealed Sept. 2.

“Depending on how many of these young crabs actually survive to adulthood, this could be one bright spot for the fishing industry in a few years,” said Mike Litzow, survey lead and director of the Alaska Fisheries Science Center’s Kodiak Laboratory.

“We are providing these early results to stock assessment scientists and resource managers to inform science and management discussions that will occur over the next few months to identify fishery management measures for the 2023 fishing year,” Litzow said.

Last year’s survey, in the midst of those record warm waters, showed the lowest abundance of adult snow crabs and immature female crabs observed in nearly 50 years of NOAA Fisheries’ annual bottom trawl surveys of the Eastern Bering Sea.

NOAA uses data collected in this survey, plus data compiled by trained observers on commercial fishing vessels, and laboratory analysis of age and growth date to estimate population abundance and sustainably manage commercial crab and groundfish species. The survey measures the crab abundance by weight in metric tons or metric tons caught.

The dramatic decline of snow crab, as well as Bristol Bay red king crab, are being studied by federal and state biologists, with no overall conclusions to date on impact of ocean warming, ocean acidification and disease, or groundfish commercial fisheries in these areas.

Snow crab rebuilding projections and other Bering Sea/Aleutian Island crab matters are on the agenda for the October meeting of the North Pacific Fishery Management Council in Anchorage.

Using data acquired in the latest survey, researchers estimated the mature male (20,403 mt) and female snow crab (20,941 mt) are 22% and 33% lower, respectively, than the 2021 estimate. This is the lowest estimate in the time serious for mature male abundance and third lowest for mature female abundance.

Researchers said this was not surprising, as it often takes several years to see population and ecosystem shifts after significant environmental events such as the heatwaves of 2016 2018 and 2019 in the Bering Sea.

NOAA Fisheries has developed survey abundance estimates for the seven commercial crab stocks sampled in this survey, including snow crab, Bristol Bay red king crab, tanner crab, St. Matthew Island blue king crab, Pribilof Islands red king crab, Pribilof Islands blue king crab and Northern District red king crab.

Bristol Bay red king crab mature and immature male and female biomass estimates were higher than a year ago, although compared with historic values, male and female populations remain low across all size classes.

Estimated legal size male biomass was about 18,060 mt, which was higher than 2021, but less than the previous 20-year average of 27,106 mt. The majority of legal males were concentrated around central Bristol Bay and south to the Black Hills.

Source: https://fishermensnews.com/mature-snow-crab-struggling-in-eastern-bering-sea-but-immature-numbers-rising/