Sea otters have been the victim of heavy exploitation for the fur trade. Pollution and habitat degradation have also been significant threats.
The California or "southern" sea otter was once thought extinct, a victim of the rapacious fur trade at the turn of the century. Discovery of a colony of surviving otters along a remote stretch of the Big Sur coast in 1938 gave this animal a second chance. It was determined to be a threatened species in 1977.