Northern Sea Otter

U.S. Fish & Wildlife Service Threatened and Endangered Species Northern Sea Otter (Southwest Alaska Distinct Population Segment) (Enhydra lutris kenyoni) Sea otters are the smallest marine mammal and are most closely related to river otters. Adult sea otters can reach lengths of up to 6 feet (1.8 m) but average about 4.5 feet (1.4 m). Adult male otters typically weigh 70-90 pounds (32-41 kg), while females average 40-60 pounds (18-27 kg). Unlike other marine mammals, sea otters do not have a blubber layer; instead they depend upon a dense, water-resistant fur to provide insulation against cold. Status The world-wide sea otter population was drastically reduced to just a few hundred animals between 1742-1911, due to commercial harvest by the Russian and Russian/American fur trades. Three stocks of sea otters exist in Alaska today. The Southwest Alaska Distinct Population Segment USFWS (DPS), which inhabits the Aleutian Islands, Alaska Peninsula coast, and Kodiak Archipelago, is listed as threatened under the Endangered Species Act (ESA). This population Nearshore marine areas provide protection from marine predators. once contained over half of the world’s sea otters. Between 1992-2000, there was a decline of about 70% in this Threats population. The population estimate most pups are born in late spring. Sea Although commercial harvest in the draft recovery plan is about otters generally have a single pup drastically reduced historical 54,000. during each breeding cycle and the populations to a few hundred animals gestation period can be highly variable at the beginning of the 20th century, Range and Population Size due to delayed implantation of the the cause(s) of more recent declines Historically, sea otters occurred in fertilized egg. A pup will weigh from is uncertain. The weight of evidence nearshore waters around the North 3-5 pounds (1.4-2.3 kg) at birth and suggests that killer whale (Orcinus Pacific rim from Hokkaido, Japan stay with its mother for 3-6 months. orca) predation is the most likely through the marine coastal areas of cause of the sea otter’s recent decline the Russian Far East and the Pacific Sea otters compensate for having a in the Western Aleutian Islands coastal areas in the United States as small body size and no blubber layer management unit, and it is presumed far south as Baja California. by having an increased metabolism, to be of moderate or high importance which helps them keep warm in the in the other management units as well. Life History and Habits cold water. Sea otters in captivity However, there are other potential Sea otters live an average of 15-20 will consume up to 25% of their threats that will require additional years. Females do not begin to breed body weight per day. Sea otters eat exploration to determine if and to until age 2-5 years; they may breed primarily benthic (bottom-dwelling) what degree they are impacting the annually up until age 20. Males become invertebrates; for example, in the Southwest Alaska DPS. These include: sexually mature after 4-6 years, but Aleutians their diet consists mostly of oil spills (which foul sea otters’ fur so may not hold breeding territories sea urchins, crabs, octopus, and some that it does not provide insulation), until several years later. In Alaska, bottom fishes. pollutants, infectious disease, disturbance from recreational and industrial activities, fishery bycatch, illegal take, and subsistence harvest. Katrina Mueller / USFWS Critical Habitat Management and Protection In 2009, the U.S. Fish and Wildlife In the United States, the Northern The goal of the recovery program Service (Service) designated sea otter is protected from hunting is to control or reduce threats to approximately 5,900 square miles and harassment by the Marine the Southwest Alaska DPS to the of nearshore marine waters as Mammal Protection Act (MMPA) of extent that it no longer requires the critical habitat for this threatened 1972. Subsistence hunting is allowed protections afforded by the ESA. To population of sea otters. The physical under both the MMPA and ESA in achieve this goal, the draft recovery and biological features believed to be Alaska. Re-introduction of sea otters plan identifies three objectives: essential to sea otter conservation are reestablished populations in Alaska, those that provide cover and shelter Canada, and Washington, expanding 1. achieve and maintain a self- from marine predators, especially their range back into places they were sustaining population of sea otters killer whales. These areas primarily extirpated. in each management unit consist of shallow (less than 20 meters deep), nearshore (within 100 meters of The Service is the Federal agency 2. maintain enough sea otters to the mean tide line) waters. responsible for maintaining healthy ensure that they are playing a populations of sea otters. In Alaska, functional role in their nearshore Federal agencies that undertake, fund, biologists from the Service, Alaska ecosystem or permit activities that may affect SeaLife Center (ASLC), and U.S. sea otters are required to consult with Geological Survey (USGS), monitor 3. mitigate threats sufficiently to the Service to ensure such actions their population health and status. ensure persistence of sea otters. do not pose a risk to the population, or adversely modify or destroy In March 2006, the Service formed Predation by killer whales is designated critical habitat. The a recovery team to develop a draft considered a likely threat to the designation of critical habitat does not recovery plan for the Southwest recovery of this DPS, but other affect land ownership or establish a Alaska DPS of the northern sea otter. threats are also considered in the refuge, wilderness, reserve, preserve, The draft plan was released for public draft recovery plan. Threats are or other conservation area. It does not review and comment in October 2010. summarized in general, and their allow government or public access to Recovery Team members were relative importance is assessed for private lands or limit public access to appointed from the following each of the five management units. public or private lands and waters. organizations: University of Alaska The draft recovery plan contains Fairbanks, University of British a thorough analysis of available The Service does not anticipate that Columbia, Marine Conservation information relating to these potential designation of critical habitat for Alliance, USGS, Alaska Veterinary threats, as well as tasks designed to the Southwest Alaska DPS of the Pathology Services, Defenders of gain additional information to fill data northern sea otter will result in any Wildlife, National Marine Fisheries gaps. closure of commercial fishing in the Service, ASLC, Alaska Department of region. Because of their dependence Fish and Game, Smithsonian National We are currently revising the draft on benthic prey items, sea otters Zoological Park, The Alaska Sea Otter recovery plan to address public spend the vast majority of their time and Steller Sea Lion Commission, comments and will be releasing a final in shallow water, typically close to the University of California (Santa Cruz), plan in the near future. shore, and this preference is reflected and the University of Alaska Sea in those areas designated as critical Grant Program. habitat. For more information contact: Verena Gill U.S. Fish and Wildlife Service 1011 E Tudor Road Anchorage, Alaska 99503 (907) 786-3584 [email protected] May 2012 http://alaska.fws.gov/fisheries/mmm/index.htm.

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