Valuable crab populations in warming waters of Alaska’s Bering Sea in “very frightening” decline


SEATTLE – Federal biologist Erin Fedewa boarded a research vessel in June at Dutch Harbor and visited a strip of the Bering Sea that typically produces an abundance of young snow crabs in annual surveys.

Not this summer. Here and elsewhere, sampling nets found surprisingly few – a drop of over 99% in immature females from those found three years earlier.

Biologists have also seen significant drops in the numbers of mature snow crabs as they painstakingly sorted out the marine life they were carrying.

“Juveniles were obviously a red flag, but just about every size of snow crab was in dramatic decline,” Fedewa said. “It’s very scary.”

This collapse of the Bering Sea snow crab population comes amid a decade of rapid climate change, which has disrupted one of the most productive marine ecosystems on the planet in a way that scientists are starting all just understand. The changes are forcing them to reconsider how they develop models to predict harvest seasons.

As the waters warm, some older crabs have moved northwest, young crabs are being engulfed by increasing numbers of predators, and disease is on the rise. All of this could make the crab more vulnerable to overharvesting, which has heightened concerns about the impacts of trawlers accidentally picking up crab as they drag nets along the seabed targeting groundfish.

The forecast for the 2022 winter snow crab season is bleak. At best, it should be considerably less than £ 12million. That would be down from a harvest of 45million pounds in 2021 and a fraction of the more than 300million pounds taken in two peak years in the early 1990s.

[Fish Factor: Good news in the crab fishery comes from the Gulf of Alaska]

The iconic red Bering Sea king crab, which can grow to 24 pounds with a leg span of up to 5 feet, is also in trouble. In a blow to commercial crabbers, many of whom are based in Washington, the October harvest for these crabs was canceled, which has only happened three times before.

According to Jamie Goen, executive director of Seattle-based Alaska Bering Sea Crabbers, the comprehensive conservation measures are expected to wipe out most of the value of the annual Bering Sea crab harvest, worth more than $ 160 million over the past year.

“We’ve received a double hit, and the economic impact is unlike anything we’ve experienced in this industry,” Goen said.

The reduction in catches will also affect some communities in Alaska that depend on crabbing fleets to help support their economies. St. Paul, in the Pribilof Islands northwest of Dutch Harbor, is the site of a major crab processing plant operated by Seattle-based Trident Seafoods, and depends on the crab fishery not only to generate revenue. ‘activity for its port, but also to pay taxes that prop the local government.

Crab fishermen want to do more to protect crab from certain types of fishing, including trawling.

Goen said crab fishermen will pressure fisheries managers to step up protective measures, such as expanding areas where trawling is not allowed and finding a way to estimate the number. invisible deaths of crabs passing under the nets.

“We need others [fishing] sectors to come forward and protect the crab, ”Goen said.

[‘We’ve never seen this before’: Salmon collapse sends Alaskans on Lower Yukon scrambling for scarce alternatives]

King crabs and snow crabs are caught off the coast of Alaska by steel-frame traps set along the bottom by a fleet of about 60 vessels. Each boat typically employs six to seven crew members, some of whom were featured in the Discovery Channel’s long-running reality series “Deadliest Catch”.

Most of the king and snow crab catches sold in the United States in recent years have been imported from other countries.

But the pullback in US stocks could push consumer prices higher.

Less ice, warmer water

Ocean conditions are critical for scientists studying the decline of the Bering Sea crab, which for all species is now estimated to be at its lowest overall level in more than four decades.

“It’s huge,” said Bob Foy, director of the Alaska Fisheries Science Center for the National Oceanic and Atmospheric Administration. “This is a massive change for our ecosystem in the Bering Sea, and the implications for other fisheries are just starting to be reflected.”

He notes that juvenile snow crab appeared to be on an increasing trend just two years ago. Then, within 48 months, they appear to have imploded.

One of the lines of research is Bering Sea ice, which forms every winter and acts as a giant platform for the growth of algae at the base of the food chain. When it freezes, the ice throws up a dense layer of cold, brackish seawater that eventually forms a cold pool at the bottom, ideal conditions for young snow crabs.

During some recent winters there has been a great reduction in the extent and thickness of the ice.

During those weak ice years, the size of the cold pool shrank, a retreat closely mapped by federal researchers.

One of the crab’s voracious predators – cod – does not like cold temperatures in the cool pool. Warmer temperatures appear to have allowed cod to hunt many more young snow crabs, according to Fedewa, who said analysis of cod bellies shows they are eating more crab.

“The hypothesis is that the thermal barriers in the cold water habitat that have protected juvenile snow crabs from predators like Pacific cod are breaking down,” Fedewa said.

King crabs can also suffer from increased predation.

Earlier federal research in the 1980s showed that young Bristol Bay sockeye salmon like to feed on king crab larvae. In recent years, there has been a series of strong returns of sockeye salmon which may be due, at least in part, to warmer and more favorable conditions in the lakes where they breed before heading into the water. salty.

“This is a hypothesis that needs to be investigated further,” Fedewa said.

Populations on the move

Warming trends in the Bering Sea appear to be increasing the number of crabs found further north. Trends, followed through surveys, are not fully understood.

The fall harvest of king crab from the Bering Sea was canceled due to the low number of mature females.

But this summer’s survey showed an increase in the number of mature female king crabs in areas further north. These crabs were counted outside the main survey area and therefore were not used to calculate potential catches.

Snow crab populations also appear to be on the move.

Last winter, crab captains reported an unusual harvest season when the main concentrations of snow crab were found some 500 miles northwest of Dutch Harbor, about double the typical distance for fishing in February and March.

“The crab we found was a good crab. They were just a lot further away than we traditionally fished, ”said Tom Suryan, who has been fishing crab for over 40 years and is considering retiring.

Suryan, skipper of the Bristol Mariner, said he was about 60 miles from the sea border with Russia.

Other boats were even closer.

“I could literally spit across the Russian border. I mean, we were there – up to a quarter of a mile, ”said Seattle-based Arctic Sea captain Owen Kvinge, who suggests part of the American crab may have moved through the waters. Russian.

Tumultuous past

Although crab populations fluctuate, there are also accounts of collapses in Alaska that continue to haunt the industry.

In the 20th century, the Gulf of Alaska was the site of an important king crab fishery that boomed and then went bankrupt. Closed in the early 1980s, it has yet to resume.

King crab fishing in the Bering Sea also has a tumultuous history. Annual catches climbed to around 130 million pounds in the early 1980s, then crab stocks collapsed and the harvest was halted. Since 1996, after two consecutive years of closure, harvests have never exceeded 22 million pounds, and fell to 2.6 million pounds last year.

In a whistleblower complaint filed earlier this year with NOAA Fisheries, a former Kodiak-based federal fisheries biologist alleged that federal investigations in the 1970s and 1980s were conducted incorrectly, with additional strokes done at random locations and other actions taken to deliberately inflate the estimates. crab populations.

Whistleblower Braxton Dew said flawed investigations paved the way for overfishing, which he called the root cause of the king crab collapse. “It was a precipitous collapse, and it’s because of all the bogus numbers that were used,” Dew said in a recent interview.

Foy, director of NOAA’s Alaska Fisheries Science Center, said investigative methods had changed and improved since the period cited in Dew’s complaint, and that even then the results were subjected to examinations offering checks and balances.

Later this fall, the Alaska Department of Fisheries and Game is expected to decide whether the 2020 snow crab (also known as opilio) harvests can continue, and is also responsible for setting the levels for small harvests from the Bering Sea for bairdi crab and golden king crab.

In the years to come, crabbers hope that populations can rebound if strong conservation measures are quickly put in place.

Yet their livelihoods could face a perilous future if global warming precludes recovery.

“The environmental pressures are enormous,” Suryan said. “Maybe the Bering Sea crab is an indicator species – the proverbial coal mine canary. I do not know. But things are changing, we can be sure of that. “


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