They found that warmer temperatures and population density were significantly linked to higher mortality rates among mature crabs.
The reason behind the mortality event: hungrier crabs.
Snow crabs are cold-water species and found overwhelmingly in areas where water temperatures are below 2 degrees Celsius, though they can function in waters up to 12 degrees Celsius, according to the study. Warmer ocean water likely wreaked havoc on the crabs’ metabolism and increased their caloric needs.
The amount of energy crabs needed from food in 2018 — the first year of a two-year marine heat wave in the region — may have been as much as quadrupled compared to the previous year, researchers found. But with the heat disrupting much of the Bering Sea’s food web, snow crabs had a hard time foraging for food and weren’t able to keep up with the caloric demand.