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The sea otter is the
largest species of the weasel family and the smallest marine mammal. It
is sociable and endemic to northern Pacific Ocean. Three subspecies are
recognized; Enhydra lutris kenyoni occurs in Washington north
through the Aleutian Islands, Enhydra lutris lutris occurs in the
Commander Islands to northern Japan, and Enhydra lutris nereis is
found in California.
A few centuries ago, as
many as 300,000 otters lived along the shores from Baja California to
Japan. Widespread hunting beginning in 1741 extirpated the otter from
most of the coast. The numbers slowly began to recover following a
treaty in 1911 between the United States, Japan, Russia and Great
Britain provided the otter with protection from hunting. Otters are
re-populating former haunts. Most of the area west of
Prince
William Sound
is now recolonized. In
British Columbia, Alaska and Washington, populations are growing at a
rate of about 20% per year and otters are now regularly seen in places
on the west coast of Vancouver Island and a few places on the British
Columbia mainland coast. They are also present along much of the
Washington, Oregon and California coast. The California population
growth is about 5% per year.
The sea otters
distinguishable features include large flipper like hind limbs,
flattened molars and flattened tail. Males measure about 1.2 to 1.4
meters in length and females are about 1.0 to 1.4 meters long. Males
weigh up to 45 kilograms and females reach 33 kilograms. Otters that
reach adulthood can live for about 15 to 20 years in the wild.
References
Cronin, M.A., Bodkin,
J., Ballachey, B., Estes, J., and Patton, J.C. 1996. Mitochondrial-DNA
variation among subspecies and populations of sea otters (Enhydra
lutris). Journal of Mammalogy 77(2):546-557.
Ebert, E.
1968. A food habits study of the southern sea otter Enhydra lutris.
California Fish and Game 54: 33042.
Estes, J.A.
and Palmisano. 1974. Sea otters: their role in structuring nearshore
communities. Science 185: 1058-1060.
Estes, J.
A., N. S. Smith and J. F. Palmisano. 1978. Sea otters predation and
community organization in the western Aleutian islands, Alaska. Ecology
59: 822-833.
Foott, J.
O. 1970. Nose scars in female sea otters. Journal of Mammalogy 51:
621-622.
Garshells,
D. L. and J. A. Garshells. 1984. Movements and management of sea otters
in Alaska. Journal of Wildlife Management 48: 665-678.
Hall, E.
R. and G. B. Schaller. 1964. Tool-using behaviour of the California sea
otter. Journal of Mammalogy 45: 287-298.
Houk, J.
L. and J. J. Geibel. 1974. Observations of underwater tool use by the
sea otter Enhydra lutris. California Fish and Game 60: 207-208.
Kenyon, K.
W. 1975. The sea otter in the eastern Pacific Ocean. Dover, New York.
Love, J.
A. Sea otters. 1992. Fulcrum Press, Colorado.
Loughlin,
T. R. 1980. Home range and territoriality of sea otters near Monterey,
California. Journal of Wildlife Management 44: 576-582.
McShane, L.J., Estes,
J.A., Reidman, M.L., and Staedler, M.M. 1995. Repertoire, structure, and
individual variation of vocalizations in the sea otter. Journal of
Mammalogy 76(2):414-427.
Payne, S.
F. and R. J. Jameson. 1984. Early behavioural development of the sea
otter Enhydra lutris. Journal of Wildlife management 65: 527-531.
Shimek, S.
J. 1977. The underwater foraging habits of the sea otter Enhyrda
lutris. California Fish and Game 63: 120-122.
Simenstad,
C. A., J. A. Estes and K. W. Kenyon. 1978. Aleuts. Sea otters and
alternate stable-state communities. Science 200: 403-411.
Wilson, D. E. and S. Ruff. 1999. The Smithsonian book of North American
mammals. Smithsonian
Institution, Washington, D.C.
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