Scientists warn that 'borealization' due to climate change is progressing in the Alaskan sea where crab populations continue to decline
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The Bering Sea , which is located between the United States and Russia, is known as a major fishing ground for crabs and salmon, and many fishermen are fishing with the aim of making a fortune. However, the sea temperature of the Bering Sea is rising with climate change, and the snow crab is in danger.
Crab crisis in Bering Sea a sign of 'borealization' and big changes in the future, scientists warn - Alaska Beacon
https://alaskabeacon.com/2023/02/06/crab-crisis-in-bering-sea-a-sign-of-borealization-and-big-changes-in-the-future-scientists-warn/
The population of snow crabs in the Bering Sea is rapidly declining, and an estimated 1 billion snow crabs have disappeared, according to a survey in October 2022. Due to the rapid population decline, the Alaska Department of Fisheries and Game (ADF&G) announced that it would not lift the ban on snow crab fishing from 2022 to 2023.
In a presentation at the Alaska Marine Science Symposium in late January 2023, Mike Ritzow of the National Oceanic and Atmospheric Administration (NOAA) said situations like this that lead to fishing bans could become more frequent in the future. warns that there is
Regarding the ban on snow crab fishing in the Bering Sea from 2022, Mr. Ritzou said, ``The reason for the ban on snow crab fishing is the highest seawater temperature since the industrial revolution.'' Furthermore, Ritzow said, 'By the 2040s, we predict that a situation like 2022 will occur once every three years.'
According to Mr. Ritzow, the reason why the population of snow crabs that used to live in the Bering Sea is rapidly decreasing is said to be due to a phenomenon called 'borealization'. 'Borealization' is a coined word that combines the words 'Boreal' and '-ization'. It is said that the living creatures that lived in the area will move northward as the seawater temperature rises.
Snow crabs that inhabit the Bering Sea prefer cold winter sea ice and cold conditions created by the melting of drift ice from the Arctic Ocean.
However, due to rising sea temperatures due to climate change, temperatures in the Bering Sea have risen above 2 degrees Celsius even in winter, making it no longer an ideal environment for snow crabs. Furthermore, as seawater temperature rises, marine organisms that prey on juvenile snow crabs from southern waters are moving northward and becoming permanent residents. As a result, it is believed that the snow crabs that inhabit the Bering Sea are moving further north across the Bering Sea in search of water temperatures that are suitable for them and areas where there are few predators.
Bering Sea fisheries managers have devised various plans to revive crab populations, but eventually the snow crab will leave the Bering Sea and make its way further north.
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When surveyed in 2018, it was recorded that the population of snow crab in the Bering Sea was the highest ever. However, Professor Gordon Kruse of the University of Alaska said, ``The subsequent rise in seawater temperature, combined with the record crab population, increased the calories required for snow crab to about four times before 2018. As a result. It is thought that many snow crabs starved to death due to lack of food.'
According to Scott Goodman, executive director of the Bering Sea Fisheries Research Foundation, the loss from banning crab fishing in the Bering Sea is at least $1 billion, not just the $300 million calculated by Alaska. It is said that it will reach the dollar (about 140 billion yen). 'This number is a difficult challenge for the crab fishing industry,' said Goodman. 'In Alaska, a major plant for processing snow crab is currently closed,' Goodman said. It is.'
However, in a project led by Mr. Chris Long, who works at NOAA's Kodiak Research Institute, research to increase the population of naturally living crabs by releasing crab larvae raised in the laboratory is taking place.
On the other hand, even if crab larvae are released, they become suitable food for marine organisms that are natural enemies, and as a result, the current situation is the same as that of wild crabs. So a law passed in 2022 created a framework to expand licensing for non-profit hatcheries and allow the farming of the shellfish needed to grow crabs.
``If this project is successful, with funding through legislation, there is the potential for human intervention to restore crab populations in the future,'' Long said.
On the other hand, Long said, ``In one place, crab population growth may work, but in another, it may fail, and crab population growth may depend on the local environment and conditions. It may be important,' he said.
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