COSEWIC assessment and update status report on the Sea Otter in Canada 2000
Table of Contents
COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:
Please note: Persons wishing to cite data in the report should refer to the report (and cite the author(s)); persons wishing to cite the COSEWIC status will refer to the assessment (and cite COSEWIC). A production note will be provided if additional information on the status report history is required.
COSEWIC 2000. COSEWIC assessment and update status report on the sea otter Enhydra lutris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. v + 17 pp.
(http://www.registrelep-sararegistry.gc.ca/sar/assessment/status_e.cfm)
Watson, J.C., G.M. Ellis, T.G. Smith and J.K.B. Ford. 1996. Update COSEWIC status report on the sea otter Enhydra lutris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-17 pp.
Previous report(s):
Munro, W.T. 1978. COSEWIC status report on the sea otter Enhydra lutris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 12 pp.
Macaskie, I. 1986. Update COSEWIC status report on the sea otter Enhydra lutris in Canada. Committee on Status of Endangered Wildlife in Canada. Ottawa. 16 pp.
Please note the status recommended in the Section "Evaluation and Recommended Status" of the report may differ from the latest status assigned to the species by COSEWIC.
Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur la situation de la loutre de mer (Enhydra lutris) au Canada – Mise à jour
Cover illustration:
Sea otter -- Judie Shore, Richmond Hill, Ontario.
©Her Majesty the Queen in Right of Canada, 2003
Catalogue No. CW69-14/80-2003E-IN
ISBN 0-662-33559-7
COSEWIC Assessment Summary
Common name : Sea otter
Scientific name : Enhydra lutris
Status : Threatened
Reason for designation : Formerly endangered. The population is increasing and now occupies two sites off the British Columbia coast and is not in imminent danger of extirpation. However, the species remains at risk due to potential environmental contamination and fisheries conflicts.
Occurrence : BC, Pacific Ocean
Status history : Designated Endangered in April 1978. Status re-examined and confirmed Endangered in April 1986. Status re-examined and designated to Threatened in April 1996. Status re-examined and confirmed Threatened in May 2000. Last assessment based on an existing status report.
COSEWIC Executive Summary from the 1996 Status Report
Sea Otters (Enhydra lutris) once ranged across the north Pacific from the central Pacific coast of Baja California, to northern Japan. An intensive fur hunt in the 18th and 19th centuries extirpated the Sea Otter from much of its range. The species was protected in 1911, and now occupies approximately half of its historic range. Presently, the worldwide population of Sea Otters is thought to be about 150 000 animals. The British Columbia Sea Otter population, originating from 89 animals reintroduced to Vancouver Island from 1969 to 1972, has increased at a finite rate of 19.6% per year, a rate similar to reintroduced populations in Washington and southeast Alaska. In 1993, a minimum of 1078 Sea Otters were found in British Columbia. Most of these animals occurred off Vancouver Island, but at least 135 Sea Otters were found near Goose Island, 125 km north of Vancouver Island. The origin of this latter group is uncertain. Sea Otters are presently classed as endangered in British Columbia and are protected under Federal and Provincial regulations.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.
COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.
Species: Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.
Extinct (X) : A species that no longer exists.
Extirpated (XT) : A species no longer existing in the wild in Canada, but occurring elsewhere.
Endangered (E) : A species facing imminent extirpation or extinction.
Threatened (T) : A species likely to become endangered if limiting factors are not reversed.
Special Concern (SC)* : A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.
Not at Risk (NAR)* : A species that has been evaluated and found to be not at risk.
Data Deficient (DD)*** : A species for which there is insufficient scientific information to support status designation.
* : Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** : Formerly described as “Not In Any Category”, or “No Designation Required.”
*** : Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.
Environment Canada Environnement Canada
Canadian Wildlife Service Service canadien de la faune
The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.
Introduction
The Sea Otter, Enhydra lutris (Linnaeus, 1758), is one of the largest members of the family Mustelidae, but the smallest of marine mammals (Estes 1980). An adult male Sea Otter (Figure 1) may weigh up to 45 kg and attain a length of about 1.4 m; females are smaller (Kenyon 1969; Estes 1980). In contrast to other marine mammals, which rely upon blubber for insulation, Sea Otters depend upon their dense fur for protection against chilly ocean water (Kenyon 1969). The coat is light to dark brown in colour, often becoming grizzled with age, especially around the head (Kenyon 1969; Garshelis 1984). Sea Otters have a high metabolic rate consuming up to one quarter of their body weight in food each day (Riedman and Estes 1990). Sea Otters feed on benthic invertebrates, often limiting the abundance of their prey, which has wide-ranging ecological consequences on community structure (Estes et al. 1989). Previous COSEWIC (Committee on the Status of Endangered Species of Wildlife in Canada) reports on the Sea Otter population in Canada were published by Monro (1985) and MacAskie (1987).
Distribution
Sea Otters ranged historically across the Pacific rim, from northern Japan to central Baja California (Figure 2) [Kenyon 1969; Riedman and Estes 1990]. An intensive fur hunt for Sea Otters, comrnencing in the 1740s resulted in their near extinction (Kenyon 1969). Sea Otters were protected in 1911, when less than 2000 animals in 13 relic groups remained (Figure 2) [Kenyon 1969].
Several of these remnant groups declined to extinction, likely because of their small size. One such group located off the Queen Charlotte Islands, disappeared, and the last Sea Otter known to inhabit British Columbian (Canadian) waters was shot in 1929 off Vancouver lsland (Cowan and Guiguet 1960; Kenyon 1969; Monroe 1985).
The Sea Otter currently occupies approximately half of its historical range (Figure 2), extending from the northern Gulf of Alaska, westward through the Aleutian archipelago to the Karnchatka Peninsula and the Kuril archipelago (Estes 1990a). Large areas to the south of the Gulf of Alaska remain uninhabited, except for recently reintroduced populations in southeast Alaska, British Columbia, Washington, and a remnant population in California.
During the 1960s and early 1970s, Sea Otters captured at Arnchitka Island and Prince William Sound were reintroduced to unoccupied habitat in Alaska, British Columbia, Washington, and Oregon (Riedman and Estes 1990; Estes 1990b). Eighty-nine Sea Otters were reintroduced to Checleset Bay off northwest Vancouver Island; 29 in 1969, 14 in 1970, and 46 in 1972. By 1972, Sea Otters had been sighted from the Queen Charlotte Islands to Barkley Sound, suggesting that some of the translocated animals had dispersed (Bigg and MacAskie 1978). In 1977, aerial surveys found Sea Otters near the original transplant site in Checleset Bay, and off Bajo Reef, Nootka Island, 75 km to the southeast (Figure 3) [Bigg and MacAskie 1978]. Until 1991, the Vancouver Island Sea Otter population was composed of two groups, one in Checleset Bay and a second off Nootka Island (MacAskie 1987), but by 1992 the population ranged continuously from Estevan Point northwest to Quatsino Sound (Figure 3) [Watson 1993]. Between 1977 and 1991 the range of the Vancouver Island Sea Otter population expanded at a rate of 15.3% per year (Watson 1993).
In 1989 a group of Sea Otters was reported in the Goose Island Group, 125 km northwest of Vancouver Island (Figure 3). Single Sea Otters were reported in the Goose Islands in 1976 (Bigg and MacAskie 1978) and subsequently, but mothers and pups were first sighted in 1989 (D. Powers, Warden, Hakai Pass Recreational Area, c/o British Columbia Parks, Caribou District, 540 Borland Street, Williams Lake, B.C. V2G 1R8, personal communication). The origin of these Sea Otters is unknown.
Sea Otters were reintroduced to various sites in southeast Alaska from 1965-1969 (Jameson et al. 1982; Riedman and Estes 1990) and may account for confirrned sightings off the north end of the Queen Charlotte Islands. In 1969 and 1970, Sea Otters were translocated to Washington State (Jameson et al. 1986). Animals from this population may account for some of the reports of Sea Otters off southern Vancouver Island and in the Strait of Georgia. The California Sea Otter population, a relict group, extends from about Ano Nuevo Point to Point Sal (Riedman and Estes 1990p; J. Estes, National Biological Survey, University of California, Santa Cruz, California 95064, personal communication).
Protection
Sea Otters were protected in 1911 under the International Fur Seal Treaty signed by the United States, Russia, Japan and Great Britain (for Canada). In Canada, Sea Otters are protected under the Federal Fisheries Act and the British Columbia Wildlife Act and Regulations. Sea Otters were designated as an "endangered" species by COSEWIC and under the British Columbia Wildlife Act in 1980. MacAskie (1987) retained this designation. In the United States, Sea Otters are protected by the Marine Mamrnal Protection Act of 1972, which prohibits their take or harassment except for public display or scientific research. Aboriginal peoples of Alaska are permitted to take Sea Otters for traditional use. Sea Otters in California, which are considered a separate subspecies (Wilson et al. 1991), are designated as "threatened" under the U.S. Endangered Species Act of 1972 (Estes 1990b).
Population Size and Trends
Before commercial exploitation, the worldwide population of Sea Otters was between 150 000 and 300 000 animals, although these estimates are highly speculative, and some authors suggest this number may have been much larger (Kenyon 1969; Johnson 1982). Since their protection the species has recovered in many areas. Sea Otters from the northern Gulf of Alaska, through the Aleutian archipelago to the Kuril archipelago are probably at or near equilibrium density throughout much of their range (Estes 1990b). Recently reintroduced or remnant populations in southeast Alaska, British Columbia, Washington and California are increasing in size.
The British Columbia Sea Otter population, now well established with at least 1522 animals, originated from the 89 animals reintroduced from 1969 to 1972. Population surveys, conducted from fixed-wing aircraft, helicopters and small vessels, indicate the British Columbia Sea Otter population has increased at a finite rate of 18.6% per year from 70 animals in 1977 to 1522 animals in 1995 (Table 1, Figure 4, Watson 1993). This rate, which may be near rmax (Caughley 1977), is similar to that of reintroduced populations in southeast Alaska and Washington State, and is almost identical to the instantaneous rate of 17.7% per year calculated by Estes (1990a) using 1977, 1984, and 1987 data. Estes (1990a) suggests that if this growth curve is extrapolated back in time, the translocated population had declined to 28 individuals by 1973. At present, portions of the British Columbia Sea Otter population may be at equilibrium density (Watson 1993).
oI.B. MacAskie, West Coast Whale Research Foundation, 7468 Lantzville, B.C. V0R 2H0.
Conditions did not permit surveys of areas marked "-". Superscripts indicate survey method: 1fixed-wing aircraft, 2helicopter, 3small vessel, * incomplete survey.
Habitat
Sea Otters inhabit shallow coastal waters, seldom ranging more than 1 to 2 km from shore, usually foraging to depths of 30 m or less (Riedman and Estes 1990). Sea Otters forage in areas with rocky or soft substrate (Riedman and Estes 1990). Sea Otters, especially mothers with pups, appear to prefer areas with kelp canopies. Kelp, however, is not an essential habitat requirement, because large populations of Sea Otters occur in areas which lack extensive kelp beds (Riedman and Estes 1990). Habitat use varies with weather and sea state. Off Vancouver Island, for example, Sea Otters move offshore during extended periods of calm, and congregate in sheltered inshore areas during storms (Morris et al. 1981; Watson 1993).
In British Columbia, Checleset Bay Ecological Reserve 109 was established in 1981 to protect Sea Otter habitat. Sea Otters off Goose Island are located within the boundaries of Hakai Pass Recreational Area. However, these areas are under provincial jurisdiction and are only partially exempt from commercial shellfish harvest, which is under federal jurisdiction.
General Biology
Reproductive Capability
Most female Sea Otters reach sexual maturity at 3 years or older (Bodkin et al. 1993) and males between 5 and 6 years of age (Riedman and Estes 1990). Sea Otters bear a single pup at approximately one-year intervals (Bodkin et al. 1993). Pups are usually born in the water and twinning is rare (Kenyon 1969).
The number of large, dependent pups present off Vancouver Island in July suggests a peak parturition period from approximately April to July, as also observed in Alaska (Payne and Jameson 1984; Garshelis et al. 1984; Riedman and Estes 1990; Watson 1993; Bodkin et al. 1993). However, pupping can occur year round. The period of pup dependency varies between individuals, but rarely exceeds one year (Riedman and Estes 1990;, Bodkin elt al. 1993).
In British Columbia, annual estimates of the population birth rate (pups/adult) range from 0.12 to 0.33 (Watson 1993). Similar rates are reported for Alaska (0.30 pups/adult) and California (0.20 pups/adult), although the pupping period is more extended in California, making it difficult to compare population birth rates (Estes personal communication). It should be noted that pup abundance is easily over or under-estimated if areas of high and low pup production are not equally surveyed (Simon-Jackson 1986; Jarneson et al. 1986; Estes 1990a).
Species (Individual) Movement
Sea Otters are not migratory. Patterns of movement and social organization in British Columbia appear similar to those observed in Alaska and California. Sea Otters segregate by sex and age, although patterns vary somewhat with season. In general, males and females rest in different locations. Adult males occupy territories that overlap female areas especially during the autumn breeding season. In California and Alaska large groups of males are found at the edges of the sea-otter range. These groups are composed of subadult and adult males, with breeding males joining them outside of breeding season. Males generally expand into new areas first whereas females use areas which have been occupied by Sea Otters for longer periods, and expand into areas as they are vacated by male groups (Loughlin 1980; Ribic 1982a; 1982b; Garshelis et al. 1984; Wendell et al. 1986; Pitcher 1989; reviewed in Riedman and Estes 1990).
Both male and female Sea Otters establish home ranges (Jameson 1989), the size of which depends, to a large degree, upon season. The home ranges of males are substantially larger than those of females, which reflects seasonal movement of breeding males. Females are sedentary by comparison. Daily movement patterns vary with the territorial status of the male and whether or not a female has a pup (Jameson 1989, review in Riedman and Estes 1990).
Behaviour / Adaptability
Sea Otters in British Columbia are wary of humans and easily disturbed by boat traffic. Females with pups seem most sensitive to disturbance. As these areas become more utilized by tourists, Sea Otters may become less wary. Sea Otters adjacent to inhabited areas habituate to the presence of humans (eg. Woolfenden 1985).
There is substantial variation in the diet of individual Sea Otters. Sea Otters are highly adaptable in their diet, often exploiting seasonally abundant food resources such as spawning squid (Riedman and Estes 1990) or pelagic red crab during El Nino events (in Riedman and Estes 1990). In one notable example, a male otter learned to bite into discarded aluminum cans to obtain octopus which hid inside the cans (McCleneghan and Ames 1976). In California, Sea Otter dietary preferences appear to be maternally transmitted (Lyons 1989).
Sea Otters feed principally upon shellfish. However, in parts of Alaska, where Sea Otters have been long established, fish are also an important food (Estes 1977). The high proportion of fish in the diet of Sea Otters in these areas may be associated with an increase in fish abundance and decline in shellfish abundance (Estes et al. 1978). Estes (1990a) speculated that inclusion of fish in the diet of Sea Otters may increase the equilibrium density of otter populations. Foraging on fish may be a feeding strategy lost to many populations when Sea Otters were reduced to a few remnant colonies at the end of the fur hunting era (Estes et al. 1989). Sea Otters have not been observed feeding on fish in British Columbia.
Limiting Factors
Fur hunting in the 18th and 19th centuries was responsible for the extirpation of Sea Otters throughout most of their range. Today, the worldwide otter population continues to rise, with further increases expected as long as unoccupied habitat is available (Estes l990b).
Food limitation is probably the major cause of death in Sea Otter populations at or near equilibrium density (Riedman and Estes 1990). Other than humans, predators include Bald Eagles, Haliaeetus leucocephalus, (Sherrod et al. 1975), Killer Whales, Orcinus orca, (in Riedman and Estes 1990), and sharks (Ames and Morejohn 1980). Sources of Sea Otter mortality have not been studied in British Columbia. However, bald eagles are common and may represent a substantial source of pup mortality. Killer whales, although probably an insignificant source of mortality, have been seen pursuing and consuming sea otters in Kyuquot Sound, British Columbia (Watson 1993) and at Amchitka Island, Alaska (Estes personsl communication). One otter carcass recovered near Kyuquot, British Columbia, had injuries which could have been caused by a boat propeller (G. Ellis, unpublished).
Human-related threats to Sea Otters are localized and include environmental contamination, conflict with commercial fisheries, incidental take, and the possibility of the resumption of hunting by native peoples.
Environmental Contamination
Perhaps the greatest threat to Sea Otters is that of oil spills (Geraci and St. Aubin 1980; Geraci and Williams 1990; Ralls and Siniff 1990). Sea Otters are vulnerable to oil in several ways. Oil destroys the water-repellent property of the fur, allowing cold water to contact the skin, which may result in hypothermia. Inhalation of volatile petroleum vapors injures lungs and other organs. Lastly when oil is ingested through grooming or foraging it injures internal organs (Geraci and Williams 1990). Furtherrnore, Sea Otters spend much of their time in kelp beds which retain oil, and congregate in groups, which means large numbers of Sea Otters can be exposed to oil simultaneously (Ralls and Siniff 1990).
Although methods for cleaning and rehabilitating oiled otters have been developed (Costa and Kooyman 1984; Davis et al. 1988; Geraci and Williams 1990; Degange et al. 1994), their effectiveness, at a population level, has been questioned (Estes 1991). On March 24, 1989 the oil tanker Exxon Valdez ran aground in Prince William Sound, spilling 10 million gallons (37.8 million l) of crude oil. At least 1013 Sea Otters were killed (Bayha and Kormendy 1990; Estes 1991; Ballachey et al. 1994); additional carcasses undoubtedly sunk and were not recovered. On December 22, 1988, 231 000 gallons (875 000 l) of oil from the barge Nestucca spilled and spread northwards from Grays Harbour, Washington. This relatively small spill killed at least one Sea Otter in Checleset Bay, British Columbia (Waldichuck 1989; Watson 1990). The continued transportation of oil along the coast of British Columbia poses a significant threat to British Columbia's Sea Otter population.
The effect of enviromnental toxins on Sea Otters has not been well documented, although varying levels of chlorinated-hydrocarbons and heavy metals have been found in sea-otter tissue (Riedman and Estes 1990). The high rate of population growth observed throughout much of the Sea Otters' range, suggests that environmental toxins are not at present a significant threat to Sea Otters (Riedman and Estes 1990), although recent evidence suggests that locally high levels of environmental toxins may affect pre-weaning mortality in Sea Otters (Estes personal communication).
Fishery Conflicts
Sea Otters are capable of limiting the abundance of many commercial species of shellfish (Johnson 1982; Estes and VanBlaricom 1985; Pitcher 1989). This has resulted in considerable conflict between commercial shellfish harvesters and Sea Otters (Estes and VanBlaricom 1985). Sea Otters have had a significant effect upon the Pismo clam fishery in central California (Wendell et al. 1986), clam density in Alaska (Kvitek et al. 1992; Kvitek and Oliver 1992) and sea urchin abundance in parts of British Columbia (Morris et al. 1979, 1981; Breen et al. 1982; Watson 1993). Conflicts over Sea Otters and shellfish stocks are not yet a problem in British Columbia, but can be anticipated as the geographic range of Sea Otters increases.
Incidental Take of Sea Otters
Gill-net fisheries in California have probably limited or even reduced the southern Sea Otter population (Wendell et al. 1985). Incidental take of Sea Otters in net-fisheries in southeast Alaska and Prince William Sound have been reported, but the impact on the Sea Otter population is unknown (Matkin and Fay 1980; Simon-Jackson 1986). Gill-nets are used in both salmon and herring fisheries in British Columbia, but incidental take of Sea Otters has not been reported. The expansion of Sea Otters into areas where gill-net fisheries, particularly for salmon, occur could have local effects on Sea Otter abundance.
Special Significance of the Species
Once on the verge of extinction, Sea Otters have made a remarkable recovery, largely because of protective legislation, an abundance of suitable unoccupied habitat and successful reintroductions (Mason and Macdonald 1990). The worldwide population of Sea Otters is thought to be about 150 000 animals, most of which are found from the Gulf of Alaska and westward across the Aleutian archipelago (Estes 1980; Riedman and Estes 1990).
The "teddy-bear-like" appearance of Sea Otters, their near brush with extinction, important role in nearshore community structure and vulnerability to oil spills has endeared them to the public. Sea Otters do well in captivity and are popular at zoos and oceanaria. Sea Otters use rocks and other hard objects as tools to crack the exoskeletons of their prey. With the exception of primates, Sea Otters are the only mammal known to use tools.
The Sea Otter, Enhydra lutris, is the sole member of the genus Enhydra. Three subspecies are recognized; Enhydra lutris lutris which is found from the Kuril Islands to the Commander Islands; Enhydra lutris kenyoni (Wilson et al. 1991) which historically occurred from the Aleutian Islands to Oregon, and Enhydra lutris nereis or the southern Sea Otter, which is presently found only in California. The historic range of the southern Sea Otter is disputed (Riedman and Estes 1990).
In the United States, the Marine Mammal Protection Act allows aboriginal people in Alaska to harvest Sea Otters for traditional use (Samuel and Foin 1983; Simon-Jackson 1986). The number of Sea Otters harvested in this fishery has increased dramatically in recent years, from 55 animals in 1988 to at least 1030 in 1993 (J. Bodkin, National Biological Survey, 1011 East Tudor Road, Anchorage, Alaska 99503, personal communication). The impact of this harvest on local Sea Otter populations is unknown (Estes 1990b).
Sea Otters exert a significant effect upon the structure of rocky nearshore communities (Estes and Palrnisano 1974; Estes et al. 1978, 1989). By feeding on herbivorous invertebrates, particularly sea urchins, Sea Otters reduce grazing pressure and increase the growth of fleshy algae, particularly brown algae such as kelp (Estes et al. 1978; Breen et al. 1982; Watson 1993). Consequently, rocky nearshore communities in areas occupied by Sea Otters are often characterized by an abundance of fleshy algae, whereas areas without Sea Otters are dominated by sea urchins and fleshy algae are rare (Estes and Duggins in press).
Evaluation
Although aboriginal hunting may have locally extirpated Sea Otters prior to the arrival of Europeans (Simenstad et al. 1978), Sea Otter populations were driven to the brink of extinction by an intensive fur hunt commencing in the 1740s. Sea Otters were protected in 1911, and have subsequently increased to historic levels throughout much of their range. In British Columbia, the reintroduced Sea Otter population is increasing at near maximum rate (Estes 1990a; Watson 1993).
Despite increases in the size and geographic extent of Sea Otters in British Columbia, the population is still relatively small in size and restricted in distribution, making it vulnerable to environmental catastrophes such as oil spills. The species is no longer in danger of imminent extirpation from Canadian waters, but is still vulnerable to a variety of real and potential threats and should remain in a category of risk which will ensure continued protection and management. A downlisting to "threatened" would retain their status on the COSEWIC list as a species which could become endangered if the factors limiting its distribution and numbers are not controlled.
Acknowledgements
Financial support to produce this report was provided by the Canadian Wildlife Service. Field research was supported by the Canadian Department of Fisheries and Oceans, British Columbia Ministry of Environment, Lands and Parks, United States Fish and Wildlife Service, Vancouver Aquarium, University of California Santa Cruz, Western Canadian Universities Marine Biological Station, Archipelago Marine Research, West Coast Whale Research Foundation, and Friends of the Ecological Reserves. The British Columbia Ministry of Environment Land and Parks and the Department of Fisheries and Oceans made unpublished data available. The manuscript was improved by comments from James Estes, Ian MacAskie, Ric Simmons and Andrew Trites.
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