 Red king crabs are experiencing a steady decline in numbers in their native far east coastal waters for unclear reasons, though several theories for the precipitous drop in the crab population have been proposed, including overfishing, warmer waters, and increased fish predation.Fishing controls set by the United States in the 1980s and 2000s have failed to stem the decline.In the 1960s the Soviet Union transported red king crabs from the North Pacific Ocean to the Murmansk Fjord.