Why have billions of snow crabs vanished from the waters of Alaska?

Due to a dramatic 90% decline in population, the state of Alaska has canceled the snow crab harvest for the first time. Here's what we know about the disappearance of so many crabs.

Snow crabs by the billions have vanished from Alaskan waters.  Alamy Stock Photo / Danita Delimont
Snow crabs by the billions have vanished from Alaskan waters.  Alamy Stock Photo / Danita Delimont

The Alaska Department of Fish and Game (ADF&G) has had to cancel the snow crab harvest for the first time because so many have vanished from Alaskan waters. It is unknown why the crabs are disappearing so rapidly, but warming waters may be to blame.

In 2018, there were approximately 8 billion snow crabs (Chionoecetes opilio) scuttling along the Bering Sea floor. Last year, the population fell by more than 87 percent to 1 billion people.

According to Miranda Westphal of ADF&G, the lack of crabs could be due to unusually warm water in the Bering Sea in 2018 and 2019. Cold-water crustaceans may have been restricted to pockets of cold water, limiting access to food and increasing competition. According to Westphal, this could have made the crabs stressed and more vulnerable to disease and predation.

According to the US Environmental Protection Agency, snow crab populations have migrated northward by around 30 kilometers since the early 1980s, most likely due to the animals' search for colder temperatures.

The harvest of red king crabs (Paralithodes camtschaticus) in Alaska has also been halted for the second year in a row due to a lack of mature female crabs. It is unclear how long the moratorium on snow crab harvesting will last. Although the move is a financial blow to the local fishing industry, officials say it is necessary to protect the remaining crabs.

"It's likely that we'll continue to see [snow crab] declines for the next 3 to 4 years," Westphal says, noting that ADF&G found a large number of young crabs during its survey this summer. "We are optimistic that if these small crabs survive, the population will eventually recover."


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