The collapse of a species

The sea ice that used to envelop St. Paul has done so only once since 2013, and then only fleetingly.

“Now, most years it doesn’t come at all,” said Brian Brettschneider, Alaska region climatologist for the National Weather Service. “And it’s not coming this year.”

Since 1940, the average surface temperature of the central Bering Sea around St. Paul has risen 2.4 degrees Fahrenheit - with a particularly elevated period between 2014 and 2021, according to National Oceanic and Atmospheric Administration data.

The two million metric tons of groundfish harvested there each year are a crucial part of the nation’s food supply. Decades of fisheries research here had developed such a finely grained picture of the marine ecosystem that scientists used to be able to predict with startling accuracy the performance of fish and crab stocks even years out, said Bill Tweit, vice-chair of the North Pacific Fishery Management Council, which manages Alaskan fisheries including in the Bering Sea.

Climate change has blown up that confidence, an impact Tweit likened to someone pushing down the plunger on a “big box of TNT.”

The Bering Sea’s record-breaking heat wave started in 2018. Erin Fedewa, a fisheries biologist, saw firsthand the carnage wrought by this explosion during NOAA’s annual survey of crab and fish populations as the waters warmed. In 2021, she spent two months on a bottom trawl boat. Three years earlier, her nets teemed with young snow crab. Now they were coming up empty.

Between hauls, she would study the historical numbers and send messages to colleagues onshore trying to express the gravity of what she was discovering.

“Something crazy is going on here,” she recalled thinking.

The subsequent research by Fedewa and others on the disappearance of more than 90 percent of the population found that warmer water sped up the crabs’ metabolism and led to a mass starvation event.

The past few years have seen cooler waters in the Bering Sea. Snow crab started to recover and the Bering Sea fishery reopened last year with a small quota, although St. Paul’s processing plant stayed closed. Federal disaster funds and a share of tax revenue from crab delivered to other ports have helped stabilize city finances.

This winter, however, ice in the Bering Sea has again been disappointing, part of a record low across the Arctic. And for the past three months, a warm trend has reemerged.

“The southern Bering Sea is in heat wave status again right now,” said Elizabeth Siddon, a NOAA Fisheries biologist in Juneau who leads the Bering Sea ecosystem status report.