Sea otters are endangered due to large-scale population declines and hunting, but oil spills are their greatest anthropogenic threat.
Sea otters are vulnerable to large-scale population declines, with oil spills being the greatest anthropogenic threat. The Exxon Valdez oil spill of 1989 had a dramatic effect on the Alaskan sea otter population, killing approximately 5,000 individuals.
According to the Otter Foundation, the California sea otter population declined from July 2008 to July 2011. Estimates suggest a California population of approximately 2,700 individuals.
The sea otter was placed under the Endangered Species Act (ESA) in 1973 and is now listed on CITES Appendix I and II. In Canada, sea otters are protected under the Species at Risk Act. As of 2020, the sea otter is considered Endangered by the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species.