The federal Submerged Lands Act of 195320 was important to state jurisdiction over sea otter management. [128], Although the southern sea otter's range has continuously expanded from the remnant population of about 50 individuals in Big Sur since protection in 1911, from 2007 to 2010, the otter population and its range contracted and since 2010 has made little progress. [63] During this time, males patrol the boundaries of their territories to exclude other males,[63] although actual fighting is rare. In most of its range, it is a keystone species, controlling sea urchin populations which would otherwise inflict extensive damage to kelp forest ecosystems. [47] [79] Much has been written about the level of devotion of sea otter mothers for their pups – a mother gives her infant almost constant attention, cradling it on her chest away from the cold water [80] and attentively grooming its fur. This number still keeps them on track for removal from the endangered species list, although just barely. [56] Juveniles are typically independent at six to eight months, but a mother may be forced to abandon a pup if she cannot find enough food for it;[77] at the other extreme, a pup may nurse until it is almost adult size. Eventually, sea otter populations became so depleted, commercial hunting was no longer viable. Éva E. Plagányi, Douglas S. Butterworth, in Encyclopedia of Marine Mammals (Second Edition), 2009. [129][130] As of spring 2010, the northern boundary had moved from about Tunitas Creek to a point 2 km southeast of Pigeon Point, and the southern boundary has moved from approximately Coal Oil Point to Gaviota State Park. A variety of tactile behavior relating to grooming (rubbing, shaking, stroking) and other social interactions (shoving, pawing, wresting) have been documented for sea otters (Riedman and Estes, 1990). [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. Along the coasts of what is now Mexico and California, Spanish explorers bought sea otter pelts from Native Americans and sold them in Asia. It could have traveled to the state from either California or Washington. [26] With up to 150,000 strands of hair per square centimetre (nearly one million per sq in), its fur is the densest of any animal. [3] Kelp forests are extremely productive ecosystems. 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. [55] Mating takes place in the water and can be rough, the male biting the female on the muzzle – which often leaves scars on the nose – and sometimes holding her head under water. Increasing the size and range of sea otter populations would also reduce the risk of an oil spill wiping out a population. Because air is compressible, sea otters likely lose insulation while diving, and may undergo unregulated heat loss during deep dives, however the heat loss may be offset to some extent by the elevated metabolic heat produced during diving. Sea otters in US waters were originally distributed among Alaska, Washington, Oregon, and California (the “sea otter states”). The commercial abalone fishery in California was closed in late 1997, and factors such as commercial fishing, poaching, disease, and changing environmental conditions are all thought to have contributed to the decline of these commercially valuable shellfishes. The cry of a pup is often compared to that of a gull. [102] Before the 19th century, around 20,000 to 25,000 sea otters lived near the Kuril Islands, with more near Kamchatka and the Commander Islands. Otters weigh 35-90 pounds (males weigh more than females). Sea otters possess thick layers of fur for warmth and protection, and thus grooming is part of their social structure, as with many social terrestrial mammals. The second, of unknown size off the Islas San Benitos, Mexico, was extinct by the 1920s. [84] A captive male sired offspring at age 19. The state followed with establishment of the California Sea Otter Game Refuge (CSOGR) in 1941. Heat can be conserved by closing the digits and placing the flippers against the abdomen, or dissipated by expanding the digits and exposing the interdigital webbing to the environment. Copyright © 2020 Elsevier B.V. or its licensors or contributors. [2] A subsequent international ban on hunting, sea otter conservation efforts, and reintroduction programs into previously populated areas have contributed to numbers rebounding, and the species occupies about two-thirds of its former range. [24] The fur is thick year-round, as it is shed and replaced gradually rather than in a distinct molting season. [173] Unusually high mortality rates amongst adult and subadult otters, particularly females, have been reported. The Russians initially traded with the Aleuts inhabitants of these islands for otter pelts, but later enslaved the Aleuts, taking women and children hostage and torturing and killing Aleut men to force them to hunt. That’s a lot of extra food to find each day! [56] There, the sea otter eats while floating on its back, using its forepaws to tear food apart and bring it to its mouth. In these cultures, many of which have strongly animist traditions full of legends and stories in which many aspects of the natural world are associated with spirits, the sea otter was considered particularly kin to humans. [51], The sea otter is diurnal. The lighter-colored otter in the video is Nyac, a survivor of the 1989 Exxon Valdez oil spill. Sea otter pelts were given in potlatches to mark coming-of-age ceremonies, weddings, and funerals. Observations of the Bering Expedition of 1741–1742 and other voyages of exploration in the North Pacific found sea otters to be abundant throughout their range, and commercial harvest of sea otters for pelts began soon after. [33] The tail is fairly short, thick, slightly flattened, and muscular. Article V of the Treaty afforded protection to sea otters from further hunting. [71] Twins occur in 2% of births; however, usually only one pup survives. Their job is to observe sea otter foraging behavior in the wild to better understand what the otters are eating, the energy they must expend to hunt their prey and the general health and wellbeing of the resident population. [126] However, after engaging in a period of public commentary in 2005, the Fish and Wildlife Service failed to release a formal decision on the issue. Shawn E. Larson, ... Holly Ernest, in Sea Otter Conservation, 2015. [131] Recently, a toxin called microcystin, produced by a type of cyanobacteria (Microcystis), seems to be concentrated in the shellfish the otters eat, poisoning them. [52] Observations of the amount of time a sea otter must spend each day foraging range from 24 to 60%, apparently depending on the availability of food in the area. [170] Describing the public sympathy for sea otters that developed from media coverage of the event, a U.S. [160] By the 1760s, the Russians had reached Alaska. Fish and Wildlife Service (USFWS) determined that the population should exceed 3,090 for three consecutive years. [141] In most of its range, the sea otter's diet consists almost exclusively of marine benthic invertebrates, including sea urchins, fat innkeeper worms, a variety of bivalves such as clams and mussels, abalone, other mollusks, crustaceans, and snails.

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