A Sea Otter or a River Otter?

It’s only natural to assume that an otter seen on the Oregon Coast is a sea otter. However the North American river otter is a regular inhabitant of estuaries, and an occasional visitor to ocean intertidal habitats. How do you tell them apart?

North American river otter at Arch Cape, Oregon

A total of 13 otter species are found worldwide, including 7 distinct genera. Otters are mostly dependent on freshwater habitats, but 4 species are either residents or occasional inhabitants of marine environments. Of these, only 2 species are adapted to a strictly marine existence: the sea otter (Enhydra lutris) distributed along the North Pacific Ocean and the marine otter (Lontra felina) found in the southeast Pacific Ocean, and also associated with kelp and seaweed.

However, the only two otter species native to the Oregon coast are the river otter and sea otter. While lone wandering sea otters are seen occasionally in Oregon, most sightings turn out to be river otters.

If you think you have seen a sea otter in Oregon, please contact Oregon Department of Fish & Wildlife or the U.S. Fish & Wildlife Service to report your sighting!

The North American River Otter

  • Weight:15-30lbs
  • Belly swimmer, rides low in the water
  • All four feet similar size
  • Food eaten mostly onshore
  • Intertidal/shoreline foraging
  • Long round tail
  • Multiple pups/yr

The Sea Otter

  • Weight: 50 – 100 pounds
  • Very buoyant, Back swimmer
  • Propels in water with large rear feet
  • Eats in the water while on back
  • Subtidal foraging
  • Shorter flat tail
  • One pup/yr