Bering Sea crab crisis a sign of ‘borealization’ and big changes ahead, scientists warn

bunches of king crab
Clusters of snow crab legs are displayed Jan. 13 at the seafood counter at a downtown Anchorage grocery store. The product was identified as previously frozen. This season’s Alaskan Bering Sea snow crab harvest has been canceled due to low stocks. The scientists warn that the warm conditions that led to this first crop cancellation are likely to become more common in the future. (Photo by Yereth Rosen/Alaska Beacon)

The first cancellation of Alaska’s Bering Sea snow crab harvest was unprecedented and came as a shock to the state’s fishing industry and the communities that depend on it.

Unfortunately for that industry and those communities, such conditions are likely to be common in the future, according to several scientists presenting at the Alaska Marine Science Symposium in late January.

The conditions that triggered the accident were probably warmer than any extreme possible during the pre-industrial period, but can now be expected in about one in seven years, said Mike Litzow, a Kodiak-based national oceanic and atmospheric scientist. By the 2040s, such conditions can be expected to occur one in three years, he said.

Blame “borealization” for the disaster befalling the snow crab, which is an Arctic species, Litzow said. That term refers to an ecosystem that goes boreal, with groups of organisms, called “taxa” by scientists, that have been south of the Arctic until recently.

“If we think about an Arctic animal in the extreme south of its range that is exposed to really rapid warming, that inevitably leads us to the concept of borealization,” said Litzow, director of the NOAA Fisheries laboratory and shellfish assessment program. Kodiak. “As arctic ecosystems warm, those systems become prone to a change of state, where arctic taxa, such as the snow crab, are replaced by subarctic taxa that are better able to tolerate warm, ice-free conditions.”

The snow crab is dependent on winter sea ice and the cold conditions created even after seasonal melting, he said. While they are widely dispersed throughout the Bering Sea, the sweet spot for commercial catching—the place where the crabs are large enough to be commercially valuable—is the southeastern Bering Sea.

But consecutive years of extreme heat in the Bering Sea, conditions that prevented much ice formation even in winter, kept temperatures above the 2 degree Celsius threshold that is ideal for snow crabs, and made the area suited marine life from further south, including groundfish that may prey on juvenile crabs, Litzow said.

Although fisheries managers are in the process of drawing up a detailed plan to rebuild the stock to help collectors, processors and communities in the short term, in the long term suitable snow crab habitat will be further north, he said.

That points to the need to change the management of snow crab and other fisheries, he said. “We really need to start evaluating our risks less in our lived experience and more in terms of future trends,” he said.

Borealization is occurring around the Arctic Ocean and its bordering seas as a result of climate change.

In Alaska’s Bering and Chukchi seas, that means suitable habitat for specialist Arctic species such as snow crab and fattened arctic cod is shrinking, and lower-latitude species such as Pacific cod and pollock, are increasingly found in higher latitude areas, the university said. of research led by Alaska Fairbanks has detailed. Borealization is also occurring on land, with woody plants growing further north and animal populations changing.

juvenile snow crab
Juvenile snow crabs are graded on a wooden board during a 2019 NOAA Fisheries trawl survey in the Bering Sea. (Photo provided by NOAA Fisheries)

For the Bering Sea snow crab, which in 2021 declined to the lowest abundance of adults seen in the 50-year record, the accident took several steps.

The low abundance in 2021 followed what was a record population of crabs surveyed in 2018. Dramatic increases in ocean conditions forced those snow crabs into a smaller area, said Gordon Kruze, professor emeritus in the College of Fisheries and Ocean Sciences of the UAF. The higher temperatures, combined with a much denser population, increased the metabolism of the crabs, so much so that the caloric needs of the crabs in some cases quadrupled, “resulting in mass famine,” Kruze said.

The simultaneous drop in red king crab in the Bristol Bay region was also economically devastating, but unprecedented. For the second year in a row, harvesting of that iconic Alaskan species will not be allowed. It is not the first closure of this type; the harvest was also banned for two consecutive years in the mid-1990s.

Between the snow crab and red king crab closures, the losses aren’t just the nearly $300 million in lost direct payments the state has estimated, said Scott Goodman, executive director of the Bering Sea Fisheries Research Foundation. . The losses probably amount to at least a billion dollars when all the multipliers are considered, “which really paints a bleak picture for the industry, and really any strategy to get ahead and find ways to help here is complicated,” Goodman said in the symposium.

“The reality in Alaska is that the major crab processing plants are closing down,” he said. “The reality at the community level is that the impacts are extreme. Entire fleets are tied up.”

However, an ongoing project offers a glimmer of hope that human intervention could restore populations in the future.

Chris Long, a scientist working at NOAA’s Alaska Fisheries Science Center laboratory in Kodiak, has been experimenting for several years with projects that could show how to enhance natural populations of crabs with hatchery-raised larvae. Much of his work focuses on red king crab in Kodiak, where the once-thriving king crab fishery collapsed in the 1980s and has never recovered.

In experiments carried out so far, very few of the larvae have survived after being dispersed in the water, at best about 2%, he said in his presentation at the symposium. However, that survival rate isn’t much different from what happens in the wild, where crab larvae are a tempting and ideal food for larger fish.

Legislation passed last session can help make mariculture-assisted crabbing a reality, Long said. The law, House Bill 41, expanded authorizations for nonprofit hatcheries, adding various types of shellfish to the pool of species those organizations will be allowed to farm, and created a framework for the state to regulate the cultivation of shellfish. those shellfish.

If the process works, crab breeding projects are more likely to get industry funding, thanks to the new legislation, Long said.

Whether the crab upgrade will be successful is, for now, an unanswered question. Future success could depend on precise local conditions, Long said. “In one place, crab enhancement could work. But somewhere else, you’re putting a bunch of expensive fish food into the ocean,” she said.

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