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Sea
Otter
Enhydra lutris
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 the Washington 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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