Wildlife At Risk in British Columbia.  A brochure series which will 
eventually include brochures on other Red and Blue listed species, 
including fish, invertebrates and plants, and on ecosystems.  Produced by 
the Ministry of Environment, Lands and Parks, Wildlife Branch, 780 
Blanshard St. Victoria, BC V8V 1X4. For copies of this brochure, write to 
the Wildlife Branch. Funded by Corporate Resource Inventory Initiative 
and Ministry of Environment, Lands and Parks.
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Why are Sea Otters at risk?
Prior to decimation by the fur trade, Sea 
Otters were found in a great arc around the North Pacific: from northern 
Japan via the coastlines of the Kuril Islands, Kamchatka, Commander and 
Aleutian Islands, Gulf of Alaska, British Columbia, Washington, Oregon 
and California, south to the vicinity of Cedros Island, Mexico.

Native people harvested Sea Otters throughout their range, but this was 
unlikely to have seriously reduced any populations. However, a 150-year 
period of ruthless exploitation began with Vitus Bering’s exploration of 
the Aleutians and Gulf of Alaska in 1741. The journals of such explorers, 
and the luxuriant pelts they brought back, revealed to the world the 
commercial potential of this far-flung resource. The ensuing maritime fur 
trade, with China and Europe the major markets, resulted in fierce 
competition between Russian, American, British, and Spanish traders, 
and sparked numerous territorial disputes. One of these, the “Nootka 
Controversy,” brought threats of war between Britain and Spain.

Prior to exploitation, the worldwide population of Sea Otters was 
estimated at between 150 000 and 300 000. During 126 years of Russian 
control, more than 800 000 are believed to have been taken in Alaska 
alone. Hundreds of thousands were also obtained along the Alaska to 
California coastline. By 1911, when a treaty to protect fur seals and Sea 
Otters was signed by Japan, Russia, Britain (for Canada) and the United 
States, between 1000 and 2000 Sea Otters remained in a dozen scattered 
locations from the Kuril Islands, Russia, to Prince William Sound, Alaska, 
and at one site near Carmel, California. The last Canadian record was a 
specimen obtained near Kyuquot on Vancouver Island in 1929.

Following protection, the remnant Sea Otter populations increased 
gradually. An estimated 150 000 or more now occupy most of their 
original range from the Kuril Islands to Prince William Sound, and the 
isolated remnant in California has increased to about 2000.

Like most marine mammals, Sea Otters have low reproductive rates. 
However, many new populations in formerly vacant habitats have 
increased steadily at rates as high as 17 to 20 percent per year, indicating 
that in areas where populations have not reached the limits of their 
habitat, natural mortality levels must also be quite low. In areas where 
populations have reached maximum densities, such as Amchitka Island 
in Alaska, starvation is probably the most common cause of death. 
Mortality also occurs due to excessively worn teeth, which may be 
accompanied by disease, parasitism, or infection. Severe, prolonged 
storms can also cause death of pups, aged, or weak individuals. At 
Amchitka Island, nesting Bald Eagles regularly prey on Sea Otter pups 
left untended on the ocean surface. This may also happen in other areas. 
There are reports of predation by Killer Whales, sharks and sea lions.

Human-caused mortality, though much reduced since the early 1900s, is 
still a cause for concern. The Exxon Valdez oil spill in Prince William 
Sound, Alaska, in 1989 wiped out nearly half of the Sea Otters in the oiled 
area of the Sound; the much smaller Nestucca spill off Washington in 
1988 killed at least one otter at Checleset Bay, 440 kilometres north of the 
spill site. Small amounts of oil, by affecting insulation, can cause 
hypothermia for Sea Otters, and any major spill, an ongoing threat on the 
B.C. coast, could be catastrophic. Entanglement in fishing nets may cause 
significant losses in some parts of their range. Shooting, harassment and 
general disturbance by boat traffic are of common concern in California 
where large numbers of people live in close proximity to these 
animals.

What is their status?

Following reintroduction, (see What can we 
do?), the Sea Otter population in Canada has increased to about 900 
animals and has been growing at a rate of 17 to 20 percent per year. The 
Sea Otter has been assigned Endangered status by the Committee on the 
Status of Endangered Wildlife in Canada (cosewic), and receives legal 
protection as a marine mammal under the Canada Fisheries Act. It has 
been placed on British Columbia’s Red List and has been legally 
designated as an Endangered Species under the Wildlife Act.

Throughout their range in the U.S., Sea Otters receive protection under 
the Marine Mammals Protection Act. The California population, a 
separate subspecies (variety) named the “Southern Sea Otter,” is afforded 
additional Federal protection as a Threatened Species under the U.S. 
Endangered Species Act.What do they look like?Two species of otters 
occur in British Columbia – the Sea Otter and the more widespread River 
Otter. River Otters frequent rivers and lakes, but are also common in 
saltwater along the entire British Columbia coast. An otter in the sea is 
usually not a Sea Otter!

The Sea Otter (Enhydra lutris) is our smallest marine mammal, but is one 
of the largest of the world’s 13 otter species – males weigh up to 45 
kilograms and reach 148 centimetres in length. Females are slightly 
smaller. The tail is about one-third the length of head and body; the River 
Otter’s is about two-thirds. Sea Otters are frequently seen in large social 
groups, resting or feeding on their backs in offshore kelp beds. They 
rarely go ashore, but when they do, they choose remote offshore reefs or 
bars. River Otters seldom occur in groups larger than a single family 
(although families can include three or four young), don’t rest on their 
backs, and come ashore frequently.

Sea Otter fur, consisting of sparse guard hairs and dense, soft underfur, 
varies from dark brown to reddish brown. When dry, the fur on the head 
is cinnamon to light brown. The body is entirely furred except for the tip 
of the nose, inside of the ears, and palms of the stubby mitten-like 
forefeet. The flipper-like hindfeet have short, sparse fur. Prominent 
whiskers, and the grizzled facial fur of older animals have given rise to 
the nickname “old man of the sea.”

Groups of the sociable Sea Otter are called rafts, and usually consist 
entirely of females and pups or of males. Male rafts are usually larger (up 
to 100 or more in Alaska); but female rafts may contain up to 40 adults 
with their pups. Most individuals make short daily movements between 
favourite feeding sites and more protected resting areas, resulting in 
seasonal home ranges of 5 to 10 square kilometres in size. However, 
studies in Alaska and California have shown that many adult males 
make yearly or more frequent trips of 80 to 145 km from male rafts to 
establish temporary breeding territories in female areas.What makes 
them unique?In contrast to whales and seals, which rely on their blubber 
for insulation, the Sea Otter relies on its well-groomed fur with many tiny 
air bubbles trapped in it. They have the thickest fur of any living animal, 
with an incredible 100 000 or more hairs per square centimetre. Frequent 
grooming activity prevents soiling of the fur, loss of insulation, and 
reduced buoyancy. The fur is rubbed meticulously with front and hind 
feet, the flexible otter rolling inside its baggy skin to reach the awkward 
parts. Folds of skin are squeezed between the forepaws or with the 
tongue to remove moisture. Finally the fur is aerated by blowing into it or 
churning the water to a froth with the paws.

To maintain body heat in chilly north Pacific waters, Sea Otters have a 
metabolic rate two or three times that of land mammals of similar size. 
This is made possible by a prodigious food intake (25 to 30 percent of 
body weight each day), an intestine 10 times the body length, and a rapid 
digestive rate. Air in the fur, together with large lungs (an adaptation for 
diving) cause Sea Otters to float high in the water. Other adaptations for 
diving include blood with a very high capacity to transport oxygen, and 
ear canals which can be closed. The Sea Otter has large, complex kidneys 
which allow it to drink seawater.

Sea Otters walk awkwardly on land and even in water do not have the 
speed or agility of seals. When lying face-up they move slowly by 
sculling the tail or paddling with one or both hindlimbs. Faster 
movements are always belly-down and involve up and down 
undulations of the entire body (“porpoising”) with the hindfeet and tail 
held stiffly as an extension of the body, and the forefeet held against the 
chest. Normal speeds are 1 to 5 km an hour; the maximum about 9 km an 
hour. When at rest, Sea Otters lie on their backs, usually entwined in kelp 
to hold their position, feet held high in the air to prevent heat loss.

Most of a Sea Otter’s day is spent feeding, grooming, or resting, usually 
in that order. Otters in Washington and British Columbia, where 
populations are small and food is abundant, may spend as little as 10 or 
15 percent of their day feeding, compared to 50 or 60 percent at Amchitka 
Island, where otter numbers are high and readily available foods have 
been exhausted. Most daytime foraging activity occurs in the morning 
and late afternoon, most resting around midday.

The near extinction and subsequent increase of Sea Otters has allowed 
researchers to study their effects on benthic (seabottom) plant and animal 
communities as they recolonized or were transplanted into vacant 
habitats. Many areas that were otter-free for decades, particularly rocks 
and reefs, have dense populations of sea urchins and little or no kelp 
(large algae), this having been eaten by the grazing urchins. These areas 
are described as “sea urchin barrens.” Research at Checleset Bay, 
Vancouver Island, and elsewhere has shown that introduced Sea Otters 
greatly reduce the urchin populations, allowing extensive stands of kelp 
to develop. These “kelp forests” drastically change the reef environment, 
provide habitat for fish such as perch, greenling, and lingcod, and 
moderate the effect of waves. Their foraging has thus had a profound 
influence on nearshore reef communities.

How do they reproduce?

Females breed at four years old and have one pup every one 
to two years. Males mature at five or six years but may not breed until 
somewhat older. Although young may be born at any time of year, most 
births occur in spring or early summer. Most mating in northern waters is 
in the fall. The estimated gestation period is 6 to 9 months. Spring or 
early summer births may result in better survival than births at other 
seasons.

Few births have been seen, but most are thought to occur in the water 
(unlike River Otters, seals and sea lions, which usually give birth on 
land). At birth the single pup weighs 1.4 to 2.3 kg and is well furred but 
relatively helpless. Pups receive a lot of maternal care and training until 
almost adult size, a period of six to eight months or more. Small pups 
suckle while lying on the female’s chest; when larger they nurse while 
lying beside her in the water. Females with small pups tend to be solitary 
and to act aggressively toward other otters.

Females leave pups on the surface when they dive for food. They share 
solid food with the pups shortly after birth, but larger pups aggressively 
take food from their mothers. The young begin to dive in their second 
month; the duration of dives and success in finding food increases with 
age. There is much to learn during the period of  dependency.

What do they eat?

Sea Otters dive to the seafloor to obtain a variety of invertebrate 
animals. The most common prey of Sea Otters are sea urchins, mussels, 
abalone, clams, scallops, crabs, sea snails, chitons, octopus, and squid. An 
acute sense of touch, using paws, nose, and whiskers, is very important 
for finding prey in crevices or bottom sediments, and during dim light. 
Food items are normally clasped between tough leathery pads of the two 
forepaws and brought to the surface to eat. Several food items are often 
stored in a loose pocket of skin in the armpit area for transportation and 
while feeding.

The ingenious Sea Otter uses rocks as tools to break open hard-shelled 
prey or to dislodge prey such as abalone. It is the only mammal other 
than the primates (monkeys, apes, humans) known to use tools. While 
eating, Sea Otters float on their backs, using their chest as a dinner table, 
and are often accompanied by gulls and small fish which scavenge on 
leftovers. Items such as crabs and urchins are broken open with paws and 
teeth; the teeth are modified for crushing hard foods. Hard-shelled 
mussels and clams are bashed repeatedly against a stone on the otter’s 
chest. Their rock tools range from 6 to 15 cm across, and favourite rocks 
may be carried in the armpit pouch on several successive dives.

Most foraging is at depths under 30 metres, but a dive to 100 m has been 
recorded. Research on the west coast of Vancouver Island found that 
food dives varied from 45 to 127 seconds, the longest interval between 
food dives was 180 seconds, and individuals may spend up to two hours 
diving for one kind of food.

Where do they live?

Sea Otters need 
unpolluted nearshore marine habitats, usually having depths under 40 m, 
an abundant food supply consisting primarily of shellfish, and freedom 
from excessive human disturbance. Complex coastlines having many 
islands, reefs, bays, and points provide a variety of feeding sites and 
shelter from storms, and appear to support the highest numbers of otters. 
Habitats of this nature occur along most of the outer coast of British 
Columbia. The reintroduced British Columbia population, possibly with 
the help of animals from northern Washington and southeast Alaska, 
may eventually expand their range into this vacant habitat.

B.C.’s deep, steep-sided fjords may have little to offer Sea Otters in terms 
of food, and provide little protection from strong outflow winds. Georgia 
Strait may be unsuitable due to high summer water temperatures, 
particularly in its shallow nearshore waters, or because of pollution and 
human disturbance.

What can we do?

Sea Otters were reintroduced to 
Canadian waters between 1969 and 1972. This was a cooperative effort 
involving BC Environment (Fish and Wildlife Branch), Fisheries and 
Oceans Canada (Pacific Biological Station), Canadian Armed Forces 
(Search and Rescue, Comox), U.S. Bureau of Sport Fisheries and Wildlife, 
Alaska Fish and Game Department, and U.S. Atomic Energy 
Commission. There were three releases totalling 89 Sea Otters (taken 
from Amchitka Island and Prince William Sound) at the Bunsby Islands 
in Checleset Bay, on Vancouver Island, during this time. This nucleus has 
grown to over 900, distributed from Nootka Sound to Quatsino Sound, 
and is increasing.

An Ecological Reserve covering all of Checleset Bay (the Sea Otter release 
site) was established by BC Parks in 1981, and harvest closures on many 
key shellfish eaten by the otters (clams, sea urchins, abalone) have been 
instituted in the reserve by the Department of Fisheries and Oceans 
Canada (DFO). Periodic aerial surveys are undertaken by BC 
Environment, BC Parks, and DFO.

Two status reports have been prepared and recovery and management 
plans are in preparation. BC Parks controls activities in Checleset Bay by 
issuing research, educational, and other permits. Research has been 
undertaken there on effects of Sea Otters on marine communities.

Once extinct on our coast, Sea Otters are now expanding to reoccupy 
their former habitats and to resume their role in the ecology of B.C.’s 
coastal ecosystems. Expansion to new areas will also provide increased 
opportunities for the public to view this engaging animal in the wild. The 
outlook for B.C.’s Sea Otter is good, although present populations are still 
relatively small and vulnerable. The public is urged to support programs 
aimed at preserving this valuable member of our coastal fauna.