When I was in Norway about ten years ago, I heard a story about Kamchatka crabs, introduced by Soviet scientists to Murmansk and then, due to absence of natural

When I was in Norway about ten years ago, I heard a story about Kamchatka crabs, introduced by Soviet scientists to Murmansk and then, due to absence of natural predators started migration first around North Cape and then south towards the Gulfstream. Norway captain of our yacht said, that in warmer waters crabs are more active, so they became an ecological danger of sorts. So I thought that with sea warming we should see a rise, not a drop of crab population, aren't we?