Unprecedented warming and loss of sea ice in the Bering Sea has led to dramatic shifts in snow crab population structure, suggests a survey.
The study, led by NOAA, compared recent bottom trawl survey data from the northern Bering Sea with data collected over 30 years by the Alaska Fisheries Science Center in the southeastern Bering Sea.
“Our motivation was to better understand how recent anomalous conditions are affecting the Bering Sea ecosystem,” said Erin Fedewa, NOAA Fisheries biologist. “Snow crab were an obvious species to study to look at potential effects of warming.”
Young snow crab live in colder waters migrating to warmer habitats as they mature. They support fisheries in the eastern Bering and North Atlantic but have historically been too small for commercial fishing in the colder waters of the northern Bering.
Scientists compared snow crab abundance and size, evaluating temperature and cold pool extent. The most striking finding of the study was a dramatic shift in size structure in the northern Bering Sea with numbers of the largest males increasing by more than 2000% from 2018 to 2019. The number of juveniles dropped substantially across both the eastern and northern regions, which scientists attributed to extreme warming in 2019.
The development of a self-sustaining mature snow crab population suggests a potential future fishery in the northern Bering Sea but the effects of continued warming, increased predation and declining numbers of juveniles may negatively affect production in years to come.