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Aquatic Species at Risk

Sea otter
Margaret Butschler, Courtesy of the Vancouver Aquarium Marine Science Centre

Scientific name:
Enhydra lutris
Mammals (marine)
Threatened, listed under SARA
Region: British Columbia Pacific Ocean


At a Glance

Once common across the Pacific rim from northern Japan to Baja, California, sea otters were hunted near to extinction during the fur trade of the 18th and 19th centuries. By the early 1900s, fewer than 2,000 remained. Today, sea otters occupy half of their historic range; conservation efforts, however, have increased their numbers to 150,000 worldwide.

About the sea otter

The smallest marine mammals in North America, sea otters occupy chilly coastal waters in the central and north Pacific Ocean. The animals rely on their dense, soft fur coats for warmth. It's important for otters to keep each individual hair clean otherwise their fur becomes matted and they can die from hypothermia. Sea otters usually swim on their backs on the surface of the water, using their rear flippers to propel themselves and their tails to steer. If the animals become frightened, they flip onto their stomachs and swim away, or dive under the water to escape.

How to recognize the sea otter
Averaging 1.2 metres in length, male sea otters typically weigh about 45 kilograms, females are slightly smaller. Otters have large, flat heads, large teeth to crush shells, and blunt noses with long, stiff whiskers. The animals have black eyes, very small ears, and a short, stout tail. Their front legs are small and fairly weak; their rear legs are also small, but much stronger as they're used for paddling. The otters' thick fur varies in colour from rust to dark brown to black, and is lighter on the head, throat and chest. Female sea otters mature at five to six years of age, and bear a single pup—very occasionally two—at one or two year intervals. Pups are usually born in the water.

Sea otter
Margaret Butschler, Courtesy of the Vancouver Aquarium Marine Science Centre
Sea otterBob Herger, Courtesy of the Vancouver Aquarium Marine Science Centre

Sea otters mainly eat shellfish and sea urchins, but are also highly adaptable and often eat seasonally available food. Sea otters dive up to 36 metres to find food, with average dives lasting approximately one minute. Otters need to eat 25 percent of their body weight each day to stay alive—meaning a 40-kilogram otter must find and eat 10 kilograms of food daily.

When sea otters find food, they often roll onto their backs and place their meals on their stomachs. Sometimes otters use rocks to help break open the hard shells of sea urchins and other prey. To keep from drifting away on the current while they feast, sea otters use seaweed as an anchor, twisting around and around in the kelp to remain stationary.

Where the sea otter lives

Sea otters favour shallow, coastal waters, seldom ranging more than one or two kilometres from shore. All otters, particularly mothers with pups, seem to prefer areas with kelp canopies, but seaweed is not an essential habitat requirement. Habitat use varies with weather and marine conditions. Otters have been known to move offshore during extended periods of calm, and congregate in sheltered, inshore areas during storms.

Did You Know?

An improving ecosystem
During the 100 years or so that sea otters were absent from British Columbia shores, urchin populations grew unchecked and kelp forests along the rocky coastlines declined. Reintroduction of the otters has had a dramatic—and beneficial—impact on the heath of the ecosystem. Otters feed on sea urchins and other herbivorous invertebrates, which graze on seaweed. Consequently, the urchins are disappearing and the kelp forests growing. The increased seaweed growth provides a source of food for herbivorous invertebrates, creates a habitat for fish, and gentles water currents, reducing coastal erosion.

Why it's at risk

Between 1979 and 1972, 89 sea otters were successfully reintroduced to British Columbia. By 1995, the population had grown to 1,500. The otters mainly live off Vancouver Island, but can also be seen near Goose Island. Sea otters have also been reintroduced to Washington State and southeastern Alaska.

Major causes of death among sea otters are lack of food and predators. The latter include bald eagles (a significant cause of otter pup death), killer whales and sharks. The greatest threat to the sea otters' survival, however, probably comes from environmental contamination. Oil spills are particularly damaging, as oil coats the animals' fur, destroying the blanket of air that provides warmth and causes death by hypothermia. Commercial fisheries also pose significant danger; many sea otters become caught in fishing nets and drown.

What's being done

The sea otter was protected in 1911 under the International Fur Seal Treaty signed by the United States, Russia, Japan, and Great Britain for Canada. Today, the otter is protected under the federal Species at Risk Act (SARA). The otter is also protected under the federal Fisheries Act and the British Columbia Wildlife Act.

Development of a recovery strategy under SARA was started in 2002. The strategy's long-term objectives include:

  • determining the size of the sea otter population;
  • developing better assessment methods; and
  • establishing the role of otters in the near-shore community structure.

In February 2004, DFO held a series of workshops to gather information from a variety of stakeholders for a sea-otter recovery action plan.

Coastal First Nation communities are also participating in sea otter population assessments and educational activities though the federal Stewardship Program.

Once extinct from Canada, the sea otter has successfully been reintroduced to British Columbia. Subsequent population growth by 1996 enabled COSEWIC to downgrade the species from endangered to threatened.

What can you do?

Sea otters will get the protection they need only if all Canadians work together to reduce threats. Find out more about sea otters and be aware of man-made threats to the animal such as entanglement in fishing nets, water pollution, and oil spills. Do your best to reduce these threats wherever possible to better protect the sea otters habitat. Get involved with the Habitat Stewardship Program for Species at Risk (HSP) or another conservation organization.

Background information provided by Environment Canada in March 2004.