Volume 1 Pages 1 - 23 (May 1986)

Citation: Stenson, G.B. (1986) The River Otter, Lutra canadensis, in Canada.  IUCN Otter Spec. Group Bull. 1: 14 - 17

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The River Otter, Lutra canadensis, in Canada

G.B. Stenson

Fisheries Research Branch, Department of Fisheries and Oceans, St. John's, Newfoundland, Canada.

The river otter, Lutra canadensis, is found only in North America where it is distributed over much of the continent from Florida north to the arctic tundra. In Canada, river otters were present in all major waterways until at least the 18th century (Toweill and Tabor, 1982). During the 1800's however, river otters were extirpated from Prince Edward Island and the prairie grasslands areas of Alberta, Saskatchewan and Manitoba due to trapping pressure and habitat destruction. Presently, river otters are found in every province and territory in Canada with the exception of Prince Edward Island. Their range is closely related to the distribution of forested regions where they are considered to have moderate to high population levels (Parker,1982). River otters are also abundant along both the Pacific and Atlantic coasts where they have adapted to the coastal marine environment. Population levels are low or absent in some areas however, due to the unfavourable habitat or previous trapping pressures. These areas include the northern tundra - muskeg, Prince Edward Island, southern Ontario, parts of Alberta and the prairie grassland regions. Generally, the present distribution and population levels of river otters appear to be stable throughout Canada (Parker, 1982).

Because of the difficulties encountered in trying to census river otters, it is difficult, if not impossible, to determine accurately the exact number of animals present in Canada. The few population estimates which have been made are based primarily on changes in trapping statistics. Although fur returns are subject to a variety of biases, they provide the only indication of population trends available. Presently, the river otter is trapped for its fur in every province and territory in which it occurs. The total number of otters trapped in Canada has remained relatively constant over the past 30 years. Usually between 15,000 and 19,000 animals are harvested each year although a peak of 23,494 was recorded in 1980 (Statistics Canada 1985). The catch has subsequently declined to 15,615 in 1984. These changes in catch are likely related to changes in international demand and subsequent changes in the value of the fur. Average pelt prices reached a peak of $98.79 in 1979 and have since declined to $53.46 in 1984 (Statistics Canada 1985). River otters are often taken incidentally by beaver trappers, however, so the fluctuations which occur in the harvest of otters may also reflect the demand for beavers to some extent. The harvest of river otters has remained relatively stable in the different regions of Canada with almost half of the pelts originating in Ontario. There is no indication that river otter population levels 'are endangered in Canada as the result of current trapping pressure (Parker, 1982).

Because the river otter is classified as a furbearer in Canada, management is primarily the responsibility of the provincial and the territorial governments. The federal government has jurisdiction over national parks lands where all trapping is prohibited. In the provinces and territories management is based upon the use of trapping seasons, trapping licences and restrictions on trapping techniques. All, regions monitor the harvest, and at least two provinces (Alberta and Manitoba) have quotas on the numbers of animals trapped. With the exception of Prince Edward Island where it is classified as extirpated, the river otter is not considered to be threatened or
endangered in Canada.

Following the inclusion of the river otter on CITES Appendix II in 1977, the federal government began monitoring the international trade in river otters. In 1984 approximately half of the total harvest was exported from Canada. Of these, almost all (5,584) went to the United States as raw skins (McLean and Robillard, 1985). In addition, Canada also exports live river otters for zoological use and for recolonization programmes in the United States. In the past two years 13 river otters have been transferred from Ontario to Missouri in an attempt to re-establish a population in that state. There are plans for a similar recolonization programme in Nebraska (Penak, pers. comm.).

The greatest threat to the river otter in Canada is from the possibility of habitat destruction. Localized habitat destruction such as that seen in southern Ontario can affect local populations of otters (Parker, 1982). Of greater concern, however, is the possible impact of acid rain or hazardous wastes which affect large areas of the country. Like other members of the Lutrinae, Lutra canadensis relies upon the presence of clean, unpolluted water for. their food, primarily fish. Also, because the otter is high in the food chain, they are particularly susceptible to the accumulation of toxic wastes. Therefore, the widespread presence of acid rain or toxicants which can result in a lack of food or the accumulation of contaminants such as heavy metals, can severely affect river otters over much of their range. Unfortunately, very little is known about the impact toxicants can have on river otters.

Although otters are common throughout most of Canada, relatively little research has been done on this species. Within the past five years studies were conducted into aspects of reproduction (Stenson, 1985), habitat utilization (Reid, 1984) and heavy metal contamination (Wren, pers. comm.) but all have since ended and no new projects have been started. The effects of habitat alterations and the deterioration of water quality have yet to be examined. Although interest is still present, river otters are considered to be low in priority for most wildlife agencies.

For the most part, however, the future of the river otter in Canada looks bright. There is no indication that population levels are declining under the current level of trapping and Canada contains large regions of favourable habitat which appear to be supporting stable, healthy populations.

References

McLearn, R. S. and J. R. Robillard (1985) Annual report for Canada. CITES Report No. 12. Canadian Wildlife Service, Ottawa, Ontario. 57 pp.
Parker, B. J. (1982) River otter. Canadian status report for the Committee on International Trade in Endangered Species. Canadian Wildlife Service, Ottawa, Ontario. 35 pp.
Reid, D. G. (1984) Ecological interactions of river otters and beavers in a boreal ecosystem. M.Sc. Thesis, Univ. Calgary, Calgary, Alberta, Canada, 210 pp.
Statistics Canada (1985) Fur production. Annual Report No. 23-207. Dept. Supp. Serv., Ottawa, Ontario.
Stenson, G. B. (1985) The reproductive cycle of the river otter, Lutra canadensis, in the marine environment of southwestern British Columbia. Ph.D. Thesis. Univ. British Columbia. Vancouver, British Columbia, Canada, 260 pp.
Toweill, D. E. and J. E. Tabor (1982) River otter. In: Chapman, J. A. and G. A. Feldhamer (eds.). Wild Mammals of North America: Biology, Management, and Economics. John Hopkins Univ. Press, Baltimore, MD. pp. 688-703.

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