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Snow crabs have found niche in Barents Sea ecosystem

There are ten times as much snow crab as king crab in the Barents Sea, only 18 years after the first specimen was found. (Photo: Jan H. Sundet/Institute of Marine Research)

TROMSØ: Since the first five specimens of snow crab were found in the Barents Sea in 1996, the population has exploded. There is now ten times as much snow crab than king crab in the area, and scientists are just starting to find out how this new species has adopted to life in the Barents Sea.

Location

Norwegian and Russian scientists have been monitoring the population of snow crab in the Barents Sea since 2004. They have found that the snow crab is no competitor to the king crab. “It seems like the snow crab has occupied a niche in the ecosystem where there probably used to be several different species, “says Jan Henry Sundet, Senior Researcher at the Institute of Marine Research.

During the latest resource mission to the Barents Sea in 2013-2014, the scientists found large amounts of young crabs, which implies that the recruitment to the population is very good.

Uncertain origin
The first crabs in the Barents Sea were found on the Goose Bank west of Novaya Zemlya in 1996. The scientists are not sure where the crabs come from – they can have migrated here naturally, or they can have been brought here in ballast water.

The original native areas for the snow crab are the Bering Strait and the coasts of eastern Canada and western Greenland. Russian scientists have found crabs in the Chukchi Sea, Eastern Siberian Sea, Laptev Sea and Kara Sea.

Scientists have compared DNA from the snow crab in the Barents Sea with snow crabs from Canada and Greenland and concluded that they do not come from that area. There has not yet been made any comparison between crabs from the Barents Sea and the Bering Strait, but the scientist says it’s “probable, but not certain,” that they come from there.

“The snow crab shows a classical development of an alien, invasive species”, Sundet says. “After the first specimens have been found, you have a long period where very little is happening and then you get an explosion in the population”. In the Barents Sea the explosion in the population came in 2012.

Occupying a new niche in the ecosystem
The growth in the population of snow crab is enormous and will probably be an important part of the ecosystem in the Barents Sea. “Based on the experience we have form the king crab, we know that the snow crab can have a large impact on the bottom fauna. We hope to get more research on this field during this year’s missions”, Sundet says.

The snow crab is a much more Arctic species than the king crab. They prefer much colder waters and have not spread to the southern parts of the Barents Sea where the king crabs have settled. 

The scientists have found that the crabs have a very varied diet – they eat clams, worms and other smaller animals and plants found on the sea bottom. Another thing the snow crab seems to been craving is garbage. In 20 percent of the examined crabs the scientists found plastic. “This tells something about the enormous problem littering of the oceans is”.

The scientists have also found that the snow crab does not compete about food with fish in the same way as the king crab does. The king crab also feeds on capelin roe and lumpfish roe, something the snow crab does not seem to be doing. “On the contrary, the snow crab is actually food for cod”, Sundet says.

Huge commercial potential
The snow crab poses a hug commercial potential, which Norway and Russia are just about to start exploring.

“We who live by the Barents Sea are very lucky that the alien, invasive species that have settled here are of the valuable sort”, says Konstantin Sokolov of the Russian research institute PINRO. “Other places, like for example the Black Sea, have had invasions of species like jellyfish”.  “And if we see that the population of crabs becomes too large, we have the possibility to increase fishing to bring it down,” Sokolov says.

There is already a market for snow crab in the world. Both in Canada and Alaska the snow crab is regarded as a valuable resource. Canada last year caught more than 100,000 tons of crab.

The snow crab is such a new species that no regulations of commercial fishing have yet been established, neither in Russian nor in Norwegian waters. In 2013 a few vessels started fishing snow crab in the international waters of the Barents Sea. The Norwegian vessel “Arctic Wolf” caught 60 tons of crab during two trips in April 2012, Kyst og Fjord reported.

According to Konstantin Sokolov, Russia plans to open up for snow crab fishing in Russian Economic Zone in 2014.