Three subspecies of the sea otter are recognized with distinct geographical distributions and facial structures.
Three regional subspecies of the sea otter have been confirmed and are recognized with distinct geographical distributions.
Enhydra lutris lutris, the Asian sea otter, is the nominate species and ranges from the Kuril Islands north of Japan to Russia’s Commander Islands and the Kamchatka Peninsula in the western Pacific Ocean. It was first described by Linnaeus in 1758. In the eastern Pacific Ocean, Enhydra lutris kenyoni, the northern sea otter, is found throughout the Aleutian Islands and southern Alaska and was described by Wilson in 1991. It’s been reintroduced to various locations from south of Prince William Sound, Alaska along the Pacific coast of Canada and into Oregon state in the continental USA. Enhydra lutris nereis, the southern sea otter, is native to central and southern California and was described by Merriam in 1904.
The Asian sea otter is the largest subspecies and has a slightly wider skull and shorter nasal bones than both other subspecies. Northern sea otters are slightly larger than Californian otters. Adult male northern sea otters weigh 27 to 39 kilograms, while females weigh 16 to 27 kilograms. Adult male southern sea otters average 29 kilograms in mass, while females average 20 kilograms. Northern sea otters possess longer mandibles (lower jaws) while southern sea otters have longer rostrums and smaller teeth.
• Image | ©️ Andrew Reding, Some Rights Reserved(CC BY-NC-ND 2.0)
• Sources | (Allegra & Gunderson 2012; Campbell & Santana, 2017; Cronin, Bodkin, Ballachey, Estes, & Patton, 1996; Doroff & Burdin, 2015; Estes, 1980; Lockwood, 2006; Nowak, 1999; Paine, 1993; The Wikimedia Foundation, 2020b; Wilson, Bogan, Brownwell, Burdin, & Maminov, 1991)