The research team developed an innovative approach to monitor crab health by measuring energy reserves stored in the hepatopancreas, a specialized organ combining liver and pancreas functions in crabs. This method proved crucial in identifying why billions of snow crabs disappeared from Bering Sea waters. Researchers found that young crabs suffered from starvation due to unusually warm seas and crowded populations competing for scarce food.
The research offers fresh perspectives on what snow crabs need from their habitat. Findings reveal that snow crabs, which typically live in the cold pool of the Bering Sea at temperatures below 2°C, actually require water colder than 0°C to preserve the energy they need to survive. Scientists noted that a marine heatwave added extra stress, since higher temperatures raised the crabs’ metabolic rates while reducing their available food and habitat. These combined factors left many crabs without enough energy to live. The drop in numbers was especially severe among juvenile crabs, threatening the long-term health of the fishery.
The development of an expedited energetic condition metric by the team represents a significant advancement in fisheries management. Researchers have developed an early warning system to detect energy shortages that may predict population declines by linking simple measurements of hepatopancreas dry weight to complex fatty acid concentrations. Traditional monitoring techniques for crustaceans have been time intensive and costly, making surveillance difficult. With this new method, scientists can rapidly check crab health during yearly surveys, giving managers almost immediate data to support their decision making.
The study also found that snow crabs quickly regained energy after the marine heatwave, with reserves rising alongside higher population numbers from 2021 to 2024. The quick rebound indicates the population is resilient when conditions improve and population density decreases.
Researchers caution that the population remains vulnerable to future warming events. Co-author Mike Litzow, director of the Shellfish Assessment Program in Kodiak, emphasizes the critical importance of cold water habitat for sustained recovery. The study emphasized that another marine heatwave could cause a similar collapse if it occurs before the population fully recovers.
This research, funded by the North Pacific Research Board, marks an important first step in understanding crab population dynamics under climate stress. Scientists will continue monitoring throughout the Bering Sea, working to ensure that future collapses don’t catch managers and stakeholders by surprise. As Fedewa notes, the 2018–2019 collapse was completely unexpected, but the new monitoring tools and findings should better prepare researchers and managers if similar conditions emerge again.