Aliens from the Artic - the invasion of the red king crab  :

Norway: The country's shorelines and fjords are the location of a biological invasion of incredible proportions. In the depths of the North Polar Sea, a species which should not normally be here at all is gaining an ever stronger foothold: the red king crab. At the beginning of the 1960s, Russian researchers released a handful of these Pacific dwellers near Murmansk. Twenty-five years later, they reappeared with their offspring in considerable numbers. Since then, hundreds of thousands of these red king crabs overrun the seabed in the northern fjords every summer. Our sub aqua expedition shows the extent of this invasion: the entire seabed, every nook and cranny is occupied by red king crabs. Scientists at the Norwegian Institute for Maritime Research are on the trail of the secret of the red king crab.