Scientists Solve the Mystery of Vanishing Alaskan Snow Crabs

Scientists finally have an answer as to why billions of snow crabs have disappeared from the waters around Alaska in recent years. Once again, climate change is to blame for the vanishing crabs, causing ocean waters to warm.

The National Oceanic and Atmospheric Administration published a study this week that found a direct correlation between recent marine heat waves in the eastern Bering Sea and the disappearance of the snow crabs that began to be recorded in 2021. The findings come just weeks after the Alaska Department of Fish and Game canceled snow crab season for the second year in a row, as the stock was estimated to be below the regulatory threshold.

After the population of snow crabs began plummeting in early 2020, scientists sought to learn whether the snow crabs moved elsewhere or if they died.

Cody Szuwalski, lead author of the study and fishery biologist at NOAA, said that researchers looked for evidence of the crabs north of the Bering Sea, west toward Russian waters, and even into deeper levels of the oceans. What they ultimately concluded was that “it was unlikely that the crabs moved, and that the mortality event is probably a big driver.”

Instead, they deduced that warming ocean temperatures likely wreaked havoc on the crabs metabolism and increased their caloric needs, resulting in hungrier crabs.

Snow crabs are cold-water species and generally found in areas where water temperatures are below 2 degrees Celsius. And while they can still function in waters up to 12 degrees Celsius, the increased temperatures caused the crabs to have a more difficult time foraging, and ultimately weren’t able to meet the caloric demand. 

Scientists believe that the amount of food crabs needed to survive in 2018 had likely quadrupled from the year before, which was the first year of a two-year heat wave in the Bering Sea.

“2018 and 2019 were an extreme anomaly in sea ice in the Bering Sea, something that we’d never seen before,” Szuwalski told CNN. “There was maybe 4 percent of the coverage of ice that we’ve historically seen, and to know whether or not that’s going to continue going forward is hard to say.”

“When I received the 2021 data from the survey for the first time, my mind was just blown,” Szuwalski explained. “Everybody was just kind of hoping and praying that that was an error in the survey and that next year you would see more crabs. And then in 2022, it was more of a resignation that this is going to be a long road.”

But snow crabs aren’t the only marine creature suffering from rising temperatures. Nearly 700 gray whales have washed up on the Pacific coast since January 2019, and in another recent study, scientists found that the whales’ food chain had been disrupted by melting ice. 

If nothing else, the two studies serve as just another unpleasant reminder that climate change has even greater, far-reaching implications than we could have possibly imagined.