The fishes of the Central Canadian Rockies Ecosystem

I surveyed existing information in historical documents; technical publications and reports; selected file data held by Parks Canada, Alberta Fish and Wildlife and the British Columbia Ministry of Environment Lands and Parks; and interviewed reliable observers knowledgeable about selected waters to determine the native and present distribution of fishes within the Central Canadian Rockies Ecosystem (CCRE). Fifty-four species of fishes in 12 families have been reported to exist in or near the CCRE. Of these, only 33 are, or once were, native to some part of the study area or in connected adjacent waters. At least 10 native fishes have suffered impacts of significant conservation concern. One native subspecies (Banff longnose dace) is now extinct. One native species (chinook salmon) is certainly extirpated in the CCRE. Several other anadromous species (Pacific lamprey, white sturgeon, sockeye and steelhead stocks) native to the study area in the Columbia River mainstem or adjacent connected waters presumably are extirpated or landlocked. Many individual stocks of native fish also have been extirpated. Cutthroat trout and bull trout native stocks especially have been eliminated or severely depleted: both are now rare in most of the Bow River drainage. In particular, genetically-pure stocks of native westslope cutthroat trout in their native habitats are exceedingly rare and should be treated as endangered. A limited number of cutthroat stocks have been successfully introduced into previously fish-free drainages above barriers. Of the 21 introduced species, at least 13 have managed to persist somewhere within the CCRE. Introduced brook and brown trout have been especially successful, largely replacing native cutthroat and bull trout in many east slopes waters. Most rainbow trout stocks introduced into the upper Bow drainage evidently have failed to persist in the long term, but have introgressed extensively with native westslope cutthroats, especially in the Bow mainstem, Jumpingpound Creek, Elbow, Sheep and Highwood river drainages. Introduced lake trout stocks have replaced native bull trout in at least two BNP lakes even though certain native stocks of these two species coexist elsewhere in the CCRE. An introduced stock of northern Dolly Varden may pose a threat to a native bull trout stock being restored in the upper Kananaskis drainage. One introduced stock (cisco in Lake Minnewanka) derived from the Great Lakes may be of special value for conservation because stocks in lakes Ontario and Erie are thought to be endangered. The present fish fauna of the CCRE is overwhelmingly artificial, depauperate and dominated by exotic stocks; the native fish fauna largely obliterated. The ecological integrity of the natural Central Rockies Ecosystem has been irretrievably lost. A system of triage is required to salvage whatever remains of the natural state. A new set of ecosystem boundaries based on regional watersheds is proposed within which to organize aquatic ecosystem conservation and management in the future.

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