The westslope cutthroat trout is one of up to 14 subspecies of cutthroat trout and only one of two found in BC (the other is the coastal cutthroat trout). The westslope cutthroat trout is found in southeastern BC, principally the upper Kootenay River drainage, and in adjacent portions of southwestern Alberta. The westslope cutthroat trout is an iconic fish of the southern Rocky Mountains both in Canada and the US; its scientific name, Oncorhynchus clarkii lewisi, stems from the names of those two famous American explorers of the west, William Clark and Meriwether Lewis. This beautiful fish is a favourite of anglers in both countries.
The westslope cutthroat trout is currently listed as Threatened in Alberta and Special Concern in BC under Canada’s federal Species-at-Risk Act (SARA). The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) recommended the listings under SARA and identified hybridization (interbreeding) with its close relative rainbow trout (O. mykiss), which have been introduced into the range of westslope cutthroat trout on numerous occasions over the past 100 years, as a major threat to the persistence of native westslope cutthroat trout. Hybridization alters the genetic make-up of westslope cutthroat trout, which degrades its evolutionary legacy and tends to hinder its ability to survive in its native environments.
Ironically, one of the places that westslope cutthroat trout are heavily impacted by hybridization with introduced rainbow trout is in five of Canada’s Rocky Mountain National Parks (Banff, Yoho, Kootenay, Waterton, and Glacier National Parks). Rainbow trout were widely introduced into Canada’s National Parks in the early 1900s to “improve” local sport fisheries. Parks Canada now, however, recognizes that our parks should be exemplars of protecting and restoring native fish diversity (and that of other animals and plants) as part of Canada’s national biotic heritage. In a program involving Parks Canada staff, volunteers, and my lab at UBC, Parks Canada is removing introduced rainbow trout from Rainbow Lake and its outlet (Rainbow Creek) and reintroducing native westslope cutthroat trout that have been captured in nearby Sawback Lake (both are in Banff National Park). Our role at UBC was to use genetic analysis to first confirm that Sawback Lake fish were, indeed, genetically pure westslope cutthroat trout, and also to identify hybridized fish from Rainbow Creek that would be removed.
Front Range Films and Parks Canada have collaborated to make a great film, One Hundred, that describes the beauty of westslope cutthroat trout and their environments and the work of Parks Canada staff and volunteers to restore this beautiful symbol of Canadian biodiversity.