Common name
Sea otter
Scientic name
California sea otter: Enhydra lutris nereis
Alaskan sea otter: Enhydra lutris kenyoni
Russian sea otter: Enhydra lutris lutris
Body size
maximum weight of 45 kg.
Average life expectancy
males: 10 to 15 years; females: 15 to 20 years
Vocal behavior
The otter’s ‘whine’ and ‘squeal’ that is commonly heard during courtship has been found to consist of graded signals that vary over a continuum. There is a degree of complexity and richness of communication patterns believed to have evolved as a result of complex social relationships.
Physical characteristics
A coat of darkly colored (shades of brown), sparse guard hair and dense insulating fur that traps air and prevents water from contacting the skinflattened hind feet or flippers for propulsion. Retractile claws on the front feet, a loose flap or pouch of skin under each foreleg which is used to hold food items gathered from the sea bottom. Flattened, rounded molar teeth with no cutting cuspsa. Horizontally flattened tail that aids in propulsion. A manner of swimming underwater by means of vertical undulations of the hind flippers and tail. An external ear that resembles the ear of an otariid more than that of its closest relative, the river otter.
When resting, sea otters often lie on their backs among kelp or in quiet water. The most common position is with the head up, and with folded paws and chin resting on the chest.
British Columbia: 2,500-3,000 sea otters. The population increase in B.C. has slowed in recent years as because some parts of the population appear to be at equilibrium. Russia: 13,000 sea ottersAlaska: approximately 60,000-90,000 sea otters; California: 2,000 sea otters; Washington: 800
Nearshore coastal waters of less than 54 m in depth.
Fish and marine invertebrates, including various species of mussels, tunicates, sea stars, bivalves, crabs, abalone and octopus. E. lutris demonstrates significant selectivity and intelligence when foraging and consuming its prey. Otters can detect and avoid toxic shellfish if suitable low toxicity prey are available.
Foraging behavior
Otters are often observed using rocks to pound small, hard bodied prey items to gain access to the edible fleshy interior.
Mating tends to be prolonged and aggressive. Mating is aquatic and often involves violent and prolonged copulations during which the male approaches the female from behind and grasps her face and nose with his teeth, sometimes pulling her head underwater while attempting to subdue her. Some females may form pair bonds with a single male while others may mate with up to three different males during a single estrous period. Most females reach sexual maturity between 2-5 years of age, with 88% maturing by age 4. Most females have been observed to have the first pup by 3-4 years of age. Reproductive rate is maximal at 5 years of age and remains stable through to age 15. Female otters typically mate numerous times during their estrous period, which lasts several days and occurs about once each year. If a female loses her pup before weaning age, she may enter estrus and mate repeatedly two or more times in a single year. Mean gestation period is approximately 218 days; mean pup dependency period is about 153 days. The majority of pups are born in spring (February) and early summer. Groups of females periodically bring their young pups ashore to rest in a process known as hauling.  Female reproductive rates and pup survivorship are generally higher in undisturbed areas with abundant food resources.
Conservation status


Threatened in 1996 by the Committee of the Status of Endangered Wildlife in Canada (COSEWIC) and through the B.C.Wildlife Act protected by the federal government’s Canada Fisheries Act and the B.C.Wildlife Act. California population is protected by the Marine Mammal Act and the U.S. Endangered Species Act.

See: Species At Risk Public Registry