Aquafacts / Sea Otters

Sea otters 

Peruse some of our most frequently asked questions about sea otters, answered by our biologists and other reputable sources.

Quick facts

6,000

Sea otter population in British Columbia

6 to 9 months

Length of pregnancy

25% 

Of body weight eaten per day

30% 

Of day spent grooming

Where do sea otters live?

Small sea otter populations inhabit kelp forests, bays and coastal waters near islands, reefs, and fjords in the North Pacific Ocean. In British Columbia, they are found along the windswept west coast of Vancouver Island and the central coast, near Bella Bella. The only sea otters near Vancouver are the four living at the Vancouver Aquarium.

How many sea otters are there?

There are approximately 6,000 sea otters in British Columbia. The population increase in B.C. has slowed in recent years because some parts of the population appear to be at equilibrium.

Russia: approximately 22,500
Alaska: approximately 71,500
California: approximately 2,500
Washington: approximately 550

Killer whales normally prey on pinnipeds. With the decline of pinnipeds, killer whales appear to have started eating sea otters, reducing the population in the Western Aleutian Islands, Alaska by 90% from 1992 to 1999. The population in the Aleutians is presently estimated at about 6,000 – 8,000 otters.

Have there always been sea otters in British Columbia?

Historically, yes, but the coastal habitat of sea otters made them easy targets for fur traders. During the 1700s and 1800s, sea otters were hunted to extinction along the B.C. coast. The current B.C. sea otters are descendants of 89 Alaskan sea otters that were relocated to the west coast of Vancouver Island from 1969-72.

What are the differences between a sea otter and a river otter?

Sea otters are found only in the ocean and are rarely seen on land. River otters swim in rivers, streams and the ocean. They often come on shore. A sea otter’s tail appears much shorter (approximately 1/3 the length of its head and body) and flatter than a river otter’s (roughly 2/3 the length of its head and body). Sea otters have paddle-shaped hind limbs, whereas the river otters have webbed paws. Sea otters spend a lot of their time floating on their backs—they rest, groom and eat in this position. River otters do not. Sea otters are commonly seen in large groups, while river otters rarely occur in groups larger than a single family which may include 3-4 young. Sea otters usually have a single pup, born in the water. River otter pups (3-4 in number) are born on land.

What do sea otters eat?

Sea otters eat a seafood smorgasbord: clams, mussels, chitons, snails, prawns, crabs, abalone, sea urchins, squid, sea star legs and in some areas, several species of fishes. Sea otters use their sense of touch to find food; diving sea otters feel for food along the ocean floor with their sensitive front paws. They have poor underwater vision. Sea otters dine floating on their backs, using their stomachs as a table to spread out the food they have gathered. They may use rocks to crush hard-shelled food, like clams. Sea otters eat a huge amount of food (up to 25% of their body weight) every day. They need a lot of “food energy” to maintain a constant body temperature in their cold water habitat; they have no body fat to insulate them like other marine mammals so instead their fur is what keeps them warm. Their metabolic rate is 2 or 3 times that of similar-sized land mammals.

Are all sea otters endangered?

No, but some sea otter populations are endangered. The B.C. sea otter population was downlisted to threatened in 1996 by the Committee of the Status of Endangered Wildlife in Canada and through the B.C. Wildlife Act. They are protected by the federal government’s Canada Fisheries Act, and the BC Wildlife Act. The California population is protected by the Marine Mammal Act and the U.S. Endangered Species Act. Alaska’s Southwestern/Aleutian population is being considered for listing as threatened.

Are sea otters always in the water?

Sea otters mate, sleep, groom, hunt, give birth, rest and play in the ocean! In some areas, usually where there are few predators, sea otters will rest on land, but they spend most of their time at the water’s surface floating on their backs. Sea otter pups are born in water and float like corks, but they cannot swim for several weeks. A sea otter mother carries her pup on her stomach, and spends much of her day caring for her baby: feeding, protecting, teaching, and grooming. Perhaps this is why females typically have one pup at a time.

How thick is a sea otter's fur?

Sea otters have one of the thickest fur coats in the animal kingdom. An adult pelt contains between 800 million to one billion individual hairs (roughly 100,000 or more per square cm). Their fur is composed of two types of hair: long, sparse guard hair and soft, dense underfur, or pile hair. Sea otters depend on their fur to keep them warm because they have no insulating fat layer. It is critical that sea otters keep their fur clean to maintain the insulating air layer between the water and their skin. Adults spend 30 percent or more of their day grooming their fur by licking and blowing into it. At birth, a newborn sea otter’s coat, called a lanugo, acts like a life preserver and keeps the baby floating at the water’s surface. It takes at least two months before the “extra-buoyant” lanugo is fully shed. Only then can the pup dive.

References

Doroff, Angela M, Estes, James A., Tinker, M. Tim, Burn, Douglas M. and Evans, Thomas J. 2003. “Sea Otter Population Declines in the Aleutian Archipelago” Journal of Mammalogy 84(1):55-64. Enhydra lutris Fact Sheet. Oceanlink (http://oceanlink.island.net/oinfo/otterpage/otter.html) Smithsonian Institute. “Useful References on Polar Bears and Marine & Sea Otters.” Smithsonian Encyclopedia. [online bibliography]

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