Sea otters are the smallest marine mammal. They depend on their dense fur for insulation instead of blubber like other marine mammals. Typically, a female has a single pup that stays with its mother for 3-6 months. They eat a variety of invertebrates like clams, crabs, sea urchins, and snails, and can use rocks to break open the shells of prey. They live approximately 15 to 20 years.
Five Units that include all of the Aleutian Islands, Bristol Bay, The Kodiak Archipelago, the Alaska peninsula, and western Cook Inlet (5,855 square miles) are designated in Alaska. The essential elements of critical habitat are shallow, rocky areas; nearshore waters; kelp forests; and sufficient prey.
Three populations exist in Alaska, but only one (the Southwestern DPS) is listed. This population once contained over half of the world’s sea otters. Since the mid-1980s it has declined approximately 55-65 percent. Historically, the species was found in nearshore waters around the North Pacific Rim from Hokkaido, Japan, through the coastal areas of the Russian Far East, across the Aleutian chain and Gulf of Alaska, and down the Pacific coast as far south as Baja California.
Commercial harvest drastically reduced historical populations to a few hundred animals at the beginning of the 20th century. Cause of the recent decline in the southwestern population is not known with certainty, but increased predation by killer whales is likely important. Other human-caused threats include oil spills, pollutants, disturbance from recreational and industrial activities, and entanglement in fishing nets.
Introduction of sea otters reestablished populations in Alaska, Canada, and Washington expanding their range back into places they were extirpated. In the United States the Northern sea otter is protected from hunting by the Marine Mammal Protection Act, although both the MMPA and the ESA include an exemption specifically allowing Alaska Natives the right to harvest marine mammals for subsistence purposes.