The crab is now reported to have reached the Lofoten Islands, about a third of the way down the Norwegian coast, having traveled some 400 miles (680 kilometers) since the early 1990s.
"It is spreading much faster that we anticipated," Sundet said. He notes that the crab's recent population explosion parallels that of some other alien species, where rapid growth occurs only after a relatively long period, during which an animal becomes established.
In its native North Pacific, where seabed competition is tougher, red king crabs have ventured as far south as northern Japan, which is on the same latitude as southern European countries.
Estimates by scientists of the potential southern limit for the species in Europe vary widely. Some say the Lofoten Islands, some the North Sea, and some Portugal.
Crab Management
WWF Norway says the Norwegian government's management policy towards the species has been to maximize population size to increase potential catches, while ignoring the possible consequences for the marine environment.
"Considering the importance of the Barents Sea as one of the world's most productive marine ecosystems, this policy can be described as high-level gambling with international conservation values and food supplies," wrote WWF Norway secretary general, Rasmus Hansson, in a letter to the Secretariat of the Convention on Biological Diversity, in Montreal, Canada.
The environmental group says the policy constitutes a clear violation of the convention, which requires signatories like Norway to control or eradicate alien species that threaten ecosystems or native species.
Although commercial fishing for the crabs off Russia and Norway began in 2002, only mature males are allowed to be landed. All females must be returned to the sea.
However, both countries now accept that crab numbers have risen massively in recent years. In 2003 the two nations agreed to double the total annual fishing quota to 800,000 crabs. Unrestricted fishing for the species is also planned in certain areas.
"Norwegian and Russian authorities recently agreed to set a western border for the joint management of the crab stock, and it is expected that the management west of this border will be an 'extinction' strategy to keep the crab stock as low as possible," Sundet said.
Whether such a measure will be enough to stop the red king crab's relentless march is questionable. The crustacean can't be decimated by fishing alone, Sundet says, adding that further action will be needed, "independent of [the crab] being of great commercial value or not."
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