Sea otter (Enhydra lutris) COSEWIC assessment and status report 2007L chapter 6


Global Range

Sea otters occur in shallow coastal areas in the North Pacific (Figure 2). Prior to the fur trade of the 18th and 19th centuries, sea otters ranged from northern Japanto central Baja California, Mexico (Kenyon 1969). Commercial exploitation commencing in the 1740s led to near extinction of the species (Kenyon 1969). By 1911, when sea otters were protected under the International Fur Seal Treaty, the population was composed of only 13 remnant groups. Several of these, including those in the Queen Charlotte Islands, declined to extinction (Kenyon 1969). The last substantiated reports of sea otters in British Columbia come from two accounts of single animals shot off the west coast of Vancouver Island in 1929 and 1930 (Cowan and Guiguet 1960; The Province Newspaper, June 29, 1931). Presently, the sea otter occupies about one half to two thirds of its historical range throughout the Pacific. A range is given here because the declines in Western Alaska make this difficult to assess. Sea otter populations that have re-established naturally after exploitation extend from the Gulf of Alaska westward through the Aleutian Archipelago to the Kamchatka Peninsula and the Kuril Archipelago and along the California coast. Reintroduced sea otter populations extend through Southeast Alaska, British Columbia and Washington (Estes 1990). About 5-10% of the current (2004) total range of sea otters is in Canada.

Figure 2: Historical and Current Global Range of All Three Subspecies of Sea Otters

Figure 2. Historical and current global range of all three subspecies of sea otters.

Canadian Range

Sea otters were extirpated from British Columbia by 1929 (Cowan and Guiguet 1960). A total of 89 sea otters were reintroduced to Checleset Bay, British Columbia from Alaska, 29 from Amchitka Island in 1969, 14 from Prince William Sound in 1970, and 46 from Prince William Sound in 1972. Until 1987, sea otters occupied only two locations along the west coast of Vancouver Island, Checleset Bay and Bajo Reef off Nootka Island, 75 km southeast of Checleset Bay (Figure 3). By 1992, the range of the population extended continuously along Vancouver Island from Estevan Point northwest to Quatsino Sound (Watson et al. 1997). By 2004, sea otters along Vancouver Island ranged from Vargas Island, in Clayoquot Sound, northward to Cape Scott and eastward to Hope Island in Queen Charlotte Strait.

In 1989 females with pups were reported near the Goose Islands on the central British Columbia coast indicating establishment of sea otters in the area (British Columbia Parks 1995). By 2004, sea otters on the central British Columbia coast ranged continuously from the southern end of the Goose Group, northward through Queens Sound to Cape Mark at the edge of Milbanke Sound (Figure 3), Single otters are periodically reported outside the continuous range.

Figure 3: Distribution of Sea Otters in British Columbia and Place Names Mentioned in the Text Regarding Range

Figure 3. Distribution of sea otters in British Columbia and place names mentioned in the text regarding range.

Shaded areas on Vancouver Island represent range in 1977. Grey line represents the range by 1995, black line the range by 2001 and the dashed line, range expansion on Vancouver Island in 2004.

Based on the type of habitat currently occupied by sea otters in British Columbia, Washington and Alaska, much of the British Columbia coast was probably occupied by sea otters historically, although sea otters may have been rare in the numerous, deep, coastal fjords common along the coast. The current population occupies 25-33% of its historic distribution in British Columbia

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