A biological “Red Army” unstoppable in the Arctic | Polarjournal
The king crab (Paralithodes camtschaticus) is also called monster crab because of its size. With a life expectancy of up to 30 years, it can weigh up to 11 kilograms and reach a leg span of 1.80 meters.

More than 50 years ago, the then Soviet Union released giant crabs into the Barents Sea to help local fishermen. Actually, the Kamchatka crab is native to the northern Pacific Ocean. But since it was introduced to the Barents Sea in the 1960s, the species has continued to spread. While fishermen in Russia and Norway profit from king crabs, environmentalists warn of the dramatic consequences. Indeed, the giant crab, which can reach a leg span of up to 180 centimeters, is a threat to native species.

The resettlement project from the North Pacific (red) to the Barents Sea (blue) brought new impetus to the fishing industry. For the ecosystem, the crab relocation was rather problematic. (Graphic: Heiner Kubny)

The origin of king crabs in the Barents Sea goes back a long way. In the 1930s, Soviet dictator Josef Stalin had planned to support the Barents Sea fishery in order to achieve higher revenues. Other conjectures speak of the better supply of the delicacy in Moscow.

Stalin ordered that the king crab be settled in the Barents Sea. In the cold North Pacific, the crab thrives excellently, why should it not do so in the Barents Sea. Another reason was also to bring the king crab alive to Moscow. Previous attempts had porven unsucessful because of the long distances from the east of Russia. According to a legend, the long crab legs were favorite food of some Soviet generals. They therefore wanted to have a fresh supply in the Barents Sea, which is much closer to Moscow than the Far Eastern area of origin.

Stalin died in 1953 and his successor Nikita Khrushchev took over his predecessor’s ‘crab resettlement’. The plan was handed over to biologist Yuri Orlov, who in 1961 released 1.5 million king crab larvae into the Barents Sea north of Murmansk on state orders. Orlov also dumped int to the Arctic Ocean about 10,000 one- to three-year-old crabs by 1969. Authorities also added about 2,600 adult specimens. Fear of consequences due to the intervention in the ecosystem and its problems was not an issue at that time.

Eggs of a female red king crab. Each female with a life expectancy of up to 30 years lays about 400,000 to 500,000 eggs . (Photo: Eric Keto)

Expanding and voracious troops

While the Soviet Union disappeared from the scene in 1991, this biological “Red Army” (due to the red color of the animals) rushed from victory to victory. Each female produces 400,000 to 500,000 eggs in her lifetime, which can produce several thousand king crabs. Without natural enemies and food competition, crabs spread rapidly. They have already reached the west coast of Norway and soon the crabs will also be found off Spitsbergen.

King crabs have been found already in UK waters, bringing threats to the diversity of other marine life and new opportunities for the fishing industry. (Photo: IntraFish)

According to some reports, king crabs have already been spotted for the first time in massive numbers also along the British coast off Yorkshire, states the British newspaper “Daily Star”. The “monster crab” poses a threat to scallops in particular. While environmentalists fear for endangered species, some fishermen are already enjoying a big catch. Fish supplier Shaun Henderson proudly says that one of his fishermen caught nearly 250 kilos of the giant crabs in one week off Bridlington, East Yorkshire.

Crab fishing is a lucrative business for the Russian fishing fleet in the Bering Sea. In 2021 alone, catchers set a new record of 11,000 tons. A large part of the catch is processed in Norwegian plants. (Photo: FiskerForum)

Detrimental to the ecosystem

Transcontinental species transplantation proved to be a disaster for the ecology of the region. The king crabs consume everything that crosses their path. Wherever the crabs appear, biodiversity suffers. The victims are large quantities of worms, snails, starfish, fish eggs, mussels and sea urchins.

Scientists fear negative impacts in a few years on species such as cod, herring and pollock, with which Norway earns even more money. The country has recognized the threat and wants to stop it from spreading along their rugged west coast. Captured king crabs should not be thrown back into the water, even if they are small and would barely make it for animal feed. On the West Coast, the principle of eradication applies. But it is to be feared that it is already too late.

Climate change is being blamed for the first time for the cancellation of Alaska’s snow crab season. The difference between a snow crab and a king crab is easily recognizable. King crabs have 3 pairs of legs and 2 large claws, a snow crab has 4 pairs of legs and 2 smaller claws. Adult snow crabs are smaller than king crabs and weigh about 4 kilograms. Photo: Alaska Seafood)

Sharp decline in Alaska

While the Norwegians are at a loss as to how to control the spread of king crabs, crabbers in the Bering Sea have an even more serious problem. In the last three years, stocks, especially of the smaller snow crabs, have literally collapsed. The snow crab population alone has plummeted by more than 80%. The king crab season, which begins in October, has already been officially canceled again this year.

Some experts suspect that the crabs, as well as other fish species, have moved further north due to higher water temperatures. Russian fishing trawlers have already positioned themselves and are already optimistic about the future of their fishing industry.

Heiner Kubny, PolarJournal

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