[5] Male sea otters usually weigh 22 to 45 kg (49 to 99 lb) and are 1.2 to 1.5 m (3 ft 11 in to 4 ft 11 in) in length, though specimens up to 54 kg (119 lb) have been recorded. In 1973, the population in Alaska was estimated at between 100,000 and 125,000 animals. [55][181] Shellfish declines have also occurred in many parts of the North American Pacific coast that do not have sea otters, and conservationists sometimes note the existence of large concentrations of shellfish on the coast is a recent development resulting from the fur trade's near-extirpation of the sea otter. [98], Alaska is the heartland of the sea otter's range. [169] Poaching was a serious concern in the Russian Far East immediately after the collapse of the Soviet Union in 1991; however, it has declined significantly with stricter law enforcement and better economic conditions.[102]. The giant extinct sea otter Enhydritherium was propelled by its forelimbs, but modern sea otters are pelvic paddlers with enlarged hindlimbs. Sea otters, whose numbers were once estimated at 150,000–300,000, were hunted extensively for their fur between 1741 and 1911, and the world population fell to 1,000–2,000 individuals living in a fraction of their historic range. [16], Nursing lasts six to eight months in Californian populations and four to twelve months in Alaska, with the mother beginning to offer bits of prey at one to two months. [citation needed], The historic population of California sea otters was estimated at 16,000 before the fur trade decimated the population, leading to their assumed extinction. [121] By 2005, only 30 sea otters remained at San Nicolas,[122] although they were slowly increasing as they thrived on the abundant prey around the island. BrownellJr., in Encyclopedia of Biodiversity (Second Edition), 2013. The southernmost limit was Punta Morro Hermoso about 21.5 miles (34.6 km) south of Punta Eugenia, in turn a headland at the southwestern end of Sebastián Vizcaíno Bay, on the west coast of the Baja Peninsula. There was some contraction from the northern (now Pigeon Point) and southern limits of the sea otter's range during the end of this period, circumstantially related to an increase in lethal shark bites, raising concerns that the population had reached a plateau. Reported sightings of sea otters in the San Juan Islands and Puget Sound almost always turn out to be North American river otters, which are commonly seen along the seashore. In Alaska, sea otters often synchronize their sleeping time and form a raft of bodies that bob together. In addition, white abalone (Haliotis sorenseni), a species never overlapping with sea otter, had declined in numbers 99% by 1996, and became the first marine invertebrate to be federally listed as endangered. The recovery of the sea otter is considered an important success in marine conservation, although populations in the Aleutian Islands and California have recently declined or have plateaued at depressed levels. The sea otter is the heaviest (the giant otter is longer, but significantly slimmer) member of the family Mustelidae,[3] a diverse group that includes the 13 otter species and terrestrial animals such as weasels, badgers, and minks. No. Sea otters have a high metabolic rate (that is, they use a high amount of energy) that is 2-3 times that of other mammals their size. Today's population of California sea otters are the descendants of a single colony of about 50 sea otters located near Bixby Creek Bridge in March 1938 by Howard G. Sharpe, owner of the nearby Rainbow Lodge on Bixby Bridge in Big Sur. Cold water is kept completely away from the skin and heat loss is limited. Key lessons are the necessity to use multiple methods, both neutral and adaptive, to assess population status and to determine the effects that historical patterns of abundance may have on current population viability. They are the only marine mammal to have the ability to hold and manipulate their young for grooming. [65] Although sea otters can be playful and sociable, they are not considered to be truly social animals. [71] Pup mortality is high, particularly during an individual's first winter – by one estimate, only 25% of pups survive their first year. Lactation is a critical and energetically expensive period of reproduction, especially for female sea otters (Enhydra lutris) and their pups, both of which have resting metabolic rates that are ca. [5] The only member of the genus Enhydra, the sea otter is so different from other mustelid species that, as recently as 1982, some scientists believed it was more closely related to the earless seals. [172] The most widely accepted, but still controversial, hypothesis is that killer whales have been eating the otters. From 1969 to 1972, 89 sea otters were flown or shipped from Alaska to the west coast of Vancouver Island. [173] Unusually high mortality rates amongst adult and subadult otters, particularly females, have been reported. In California the harvest was pursued by hunters from Russia, often utilizing enslaved Aleut hunters, and from Spain, Mexico, and the US. [7], Fossil evidence indicates the Enhydra lineage became isolated in the North Pacific approximately 2 million years ago, giving rise to the now-extinct Enhydra macrodonta and the modern sea otter, Enhydra lutris. The authors delve into the historical views and uses of sea otters by First Nations people to understand how sea otters were managed by native people in an effort to inform contemporary ecosystem approaches to sea otter management in the modern world. [59] The Exxon Valdez oil spill of 24 March 1989 killed thousands of sea otters in Prince William Sound, and as of 2006, the lingering oil in the area continues to affect the population. Share. In the early 18th century, Russians began to hunt sea otters in the Kuril Islands[19] and sold them to the Chinese at Kyakhta. Sea otters eat about 20-30% of their body weight each day. Between producing milk to nurse their pups and sharing their prey with them, sea otter moms will expend 2X as much energy as when they don’t have a pup. [162], Russian hunting expanded to the south, initiated by American ship captains, who subcontracted Russian supervisors and Aleut hunters[163] in what are now Washington, Oregon, and California. To the surprise of biologists, the majority of the San Nicolas sea otters swam back to the mainland. The State of California enacted regulations to prohibit hunting of sea otters in 1913. Sea otters today often live adjacent to areas of high human occupancy. [168] However, the IUCN still lists the sea otter as an endangered species, and describes the significant threats to sea otters as oil pollution, predation by orcas, poaching, and conflicts with fisheries – sea otters can drown if entangled in fishing gear. (2002) to the contrary notwithstanding. In a 1997 survey, small numbers of sea otters, including pups, were reported by local fishermen, but scientists could not confirm these accounts. The sea otter accomplishes this through a metabolic rate 2.4–3.2 times higher than predicted in a terrestrial mammal of similar size. [141] In California, they have been noted to ignore Pismo clams smaller than 3 inches (7 cm) across. Lyapunova, R.G. [59] The liver, kidneys, and lungs of sea otters also become damaged after they inhale oil or ingest it when grooming. The population originally extended southward into mainland Baja California and Isla Guadalupe, Mexico, and was contiguous with other otter populations ranging through the North Pacific Rim to northern Japan. [104] The sea otter population in Prince William Sound was also hit hard by the Exxon Valdez oil spill, which killed thousands of sea otters in 1989. [178][179], Some of the sea otter's preferred prey species, particularly abalone, clams, and crabs, are also food sources for humans. In northern latitudes, sea otters may haul-out more frequently during the winter as a means to conserve heat. Sea otters in California comprise one of three subspecies currently recognized. [1] The hunting of sea otters is no longer legal except for limited harvests by indigenous peoples in the United States.
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