Species: Enhydra lutris
Sea Otter
Species
Show on Lists
Encyclopedia of Puget Sound
Pelage thick, mainly reddish, dark brown, or black, with the head whitish in older individuals, especially males; tail thick (to about 35 cm), about 1/4 of body length; hind feet flattened and webbed, outer toe longest, with vestigial leathery foot pads; front feet relatively small and round; ear pinnae small; to about 1.5 m in total length; adult males usually 25-40 kg, females usually 15-25 kg.
Articles:
This article was originally published by the Washington Department of Fish and Wildlife as part of its annual report Threatened and Endangered Wildlife in Washington.
Classification
Kingdom
Animalia
Phylum
Craniata
Class
Mammalia
Order
Carnivora
Family
Mustelidae
Genus
Enhydra
NatureServe
Classification
Other Global Common Names
loutre de mer
Informal Taxonomy
Animals, Vertebrates - Mammals - Carnivores
Formal Taxonomy
Animalia - Craniata - Mammalia - Carnivora - Mustelidae - Enhydra - Lidicker and McCollum (1997) examined allozyme variation and found that despite historical population depletion, otters from California have suffered only a small loss in genetic variability. MtDNA data also indiciate that population bottlenecks probably did not result in major losses of genetic variation in individual populations or the species as a whole (Cronin et al. 1996). However, based on microstatellite DNA and mtDNA, Larson et al. (2002) reported that the levels of genetic diversity observed within sea otter populations were relatively low when compared with other mammals and may be the result of fur trade exploitation.
Ecology and Life History
Pelage thick, mainly reddish, dark brown, or black, with the head whitish in older individuals, especially males; tail thick (to about 35 cm), about 1/4 of body length; hind feet flattened and webbed, outer toe longest, with vestigial leathery foot pads; front feet relatively small and round; ear pinnae small; to about 1.5 m in total length; adult males usually 25-40 kg, females usually 15-25 kg.
Short General Description
A marine mammal (sea otter), to about 1.5 m long.
Habitat Type Description
Marine
Migration
true - true - false - Seasonal movements occur among some age-sex classes in certain areas (Riedman and Estes 1990).
Non-migrant
true
Locally Migrant
true
Food Comments
Diet varies according to location; often dominated by benthic invertebrates. Sea urchins, crabs, and a variety of molluscs are principal foods, but fish are important food items at high population densities. Forages usually at depths of less than 20 m. Uses rocks or other hard objects as tools to break exoskeletons of invertebrate prey. Diets and patterns of foraging behavior may be highly individualized (Riedman and Estes 1990).
Reproduction Comments
Strongly polygynous. Reproduction is weakly seasonal. Births in spring and summer with peak in early summer in Alaska (late May in Prince William Sound); peak December-March (generally late winter) in California. Implantation delayed, gestation about 8-9 months in Alaska, about 4-6 months in California. Young dependent on mother for about 6-7 months in California, 76-333 days (average 170) in Prince William Sound, Alaska. In California, adult females generally give birth to 1 pup every year; females in some areas of Alaska give birth every other year. In California, females sexually mature usually in 3-5 years. In Alaska, 30% of females were sexually mature at age 2, 100% by age 5; annual reproductive rates increased from 22% at age 2 to 78% at age 5 and remained relatively stable (75-88%) through age 15 (Bodkin et al. 1993). Commonly lives 10-15 years; maximum known ages are 23 years for females and 18 years for males.
Ecology Comments
Keystone predator; often limits prey populations; predation on herbivores determines structure of off-shore kelp communities (e.g., Estes et al. 1989). <br><br>Males defend contiguous territories from which they exclude other males (Riedman and Estes 1990). <br><br>Males may move up to 30-60 miles along coast, females generally stay within area 5-10 miles long. Daily movements generally encompass a few kilometers (Riedman and Estes 1990). Ralls et al. (1996) found that otters in California usually were within 1-2 km of their location on the previous day but often stayed in one place for an extended period then suddenly moved a much greater distance; the area used by individual otters during a single 24-hour period was 7-1166 ha. <br><br>Undisturbed populations can increase at about 17-20%/year, although the central California population never has increased at more than 5-7%/year (Riedman and Estes 1990).
Length
150
Weight
35000
Conservation Status
NatureServe Global Status Rank
G4
Global Status Last Reviewed
2005-03-08
Global Status Last Changed
1996-11-18
Distribution
Conservation Status Map
<img src="http://www.natureserve.org/explorer/servlet/GetMapGif?CA.BC=S3&US.AK=S4&US.CA=SNR&US.OR=SH&US.WA=S2" alt="Conservation Status Map" style="width: 475px; height: auto;" />
Global Range
FG - 20,000-2,500,000 square km (about 8000-1,000,000 square miles) - FG - Nearshore waters of the Northern Pacific Ocean. Subspecies <i>lutris</i>: northwestern Pacific, from the Kiritappu Peninsula of eastern Hokkaido Island (formerly) and Kurile Islands to Commander Islands. Subspecies <i>kenyoni</i>: Aleutian Islands, southern Alaska, British Columbia, and Washington; extirpated and later reintroduced in southeastern Alaska, British Columbia, and Washington; extirpated and unsuccessfully reintroduced in the Pribilof Islands and Oregon. Subspecies <i>nereis</i>: California coast, mainly from Santa Cruz to Pismo Beach; formerly south to Morro Hermoso, Baja California, and throughout the Channel Islands; recently reintroduced to San Nicolas Island; see Rodriguez-Jaramillo and Gendron (1996) for an occurrence off southern Baja California. See Gallo-Reynoso and Rathbun (1997) for a discussion of possible occurrences off Baja California.
Global Range Code
FG
Global Range Description
20,000-2,500,000 square km (about 8000-1,000,000 square miles)