The snow crab fishing sector in Alaska came to a halt in 2022 following a troubling drop in crab numbers. Scientists now increasingly believe that human-driven climate change has led to an ecological transformation that wiped them out.

A recent report from the National Oceanic and Atmospheric Administration (NOAA) revealed that the rapid transition known as “borealization” – which describes the ecosystem shift from Arctic to sub-Arctic – is 98% likely due to human activities. The consequences were severe: approximately 10 billion crabs disappeared between 2018 and 2021, causing the industry’s value to plummet from $227 million to zero.

Previous research suggested that a heatwave in the Bering Sea may have increased the crabs’ metabolic rates, but without a sufficient food supply, many crabs starved to death.

“It’s even more alarming that the Arctic conditions that snow crabs need to thrive in the southeastern Bering Sea are expected to continue diminishing,” stated Mike Litzow, the study’s lead author and director of the Alaska Fisheries Science Center’s Kodiak Lab.

This poses further concerns for the crabbing sector.

What Caused the Decline of Crabs in Alaska?

From 2018 to 2021, the number of snow crabs dropped by 92%, losing about 10 billion crabs. This sudden decline caught both scientists and crab fishermen off guard since crabs had been abundant in the seasons prior.

Warming water temperatures and reduced sea ice from 2018 to 2019 created conditions that were not favorable for crab survival. Although the heightened temperatures did not overly stress the crabs directly, they did increase their metabolic needs, and there wasn’t enough available food to meet those needs.

Researchers examined changes in ice coverage, ocean floor temperatures, algae growth, and Arctic community compositions from 1972 to 2022. They found that strong boreal conditions now occur about 200 times more frequently (with a temperature rise of 1.0 to 1.5 degrees Celsius) than prior to the industrial era.

“All these changes are tied to climate change driven by human actions since the industrial revolution started in the early 20th century,” Litzow explained.

In 2022, Alaska’s Department of Fish and Game made the difficult decision to close the crab fishery for the season due to insufficient crab numbers. After little indication of recovery, the closure was extended for another year.

This year, Alaska’s Governor Mike Dunleavy requested U.S. Secretary of Commerce Gina Raimondo to declare a fishery resource disaster for the 2023-24 Bering Sea snow crab season.

“The snow crab fishery will likely remain shut for the next three to four years until younger crabs grow and reach legal size,” Dunleavy said.

Implications of Climate Change Going Forward

There is some optimism for snow crabs in the immediate future, as noted in the study published in Nature. Temperatures returned to cooler levels in 2022, resembling historical norms.

A revitalization plan for the snow crab population aims for recovery by 2029. Meanwhile, crabbers must adapt to harvesting different species, as indicated by NOAA.

The significant shifts observed in recent years highlight the need for major fishing industries to prepare for a “complete loss of Arctic characteristics in traditional fishing regions,” the study’s authors cautioned.

Further warming is anticipated over the next decade or two. The scientists pointed out that Arctic conditions may only be present in 8% of future years in the southeastern Bering Sea.

“It’s crucial for fishermen, researchers, communities, and resource managers to acknowledge that one of the world’s most productive marine ecosystems is changing at an unprecedented speed,” Litzow remarked. “We need to act now to strategize our adaptation methods.”

Contributors: Trevor Hughes and Marina Pitofsky, YSL News