Freshwater Fishes of the Columbia Basin Return to Table of Contents

The proportion of endemic fish species found in the Columbia Basin in British Columbia sets the Columbia Basin apart from other large drainage basins in North America. At present, the Columbia Basin contains 43 fish species, of which 27 are native (9 endemic), and 16 are introduced 'exotic' species. The Columbia Basin presently houses over half (43 of 84 species) of British Columbia's freshwater fish fauna, making it the parent drainage for freshwater fish diversity in British Columbia.

The breadth of fish biodiversity present in the Columbia Basin native fish fauna is easily underestimated if one merely counts the number of species present. Most diversity exists below the species level, and is represented by unique phenotypic, behavioural and life-history forms that have been selected in the isolated, mountainous terrain and glacial history characteristic of the Columbia Basin. These unique, locally adapted species of fish are part of a complex freshwater fish community that makes the ever-changing Columbia Basin a unique component of the North American Cordillera.

The successful introduction of many exotic, introduced fish species into B.C. waters during the last century appears to be correlated with the large-scale water impoundment that is now typical of the Columbia Basin. As the third longest River in North America, with a total elevation drop of nearly 1,000 metres, the Columbia River and its tributaries were obvious candidates for hydro-electric development as western North America became populated through the 20th C. The impediment that resulted as a function of impoundment and an abundance of harvesting earlier this century has left wild migratory Chinook Salmon (Oncorhynchus tshawytscha) extinct in the Canadian portion of the Columbia Basin. Anadromous Sockeye Salmon (Oncorhynchus nerka) are following suit, hovering above extinction, with only a few adults making the natal return to the Okanagan River each year. The 16 exotic species (37% of the fish fauna) found in the Columbia Basin seem to thrive in areas associated with impoundment and other anthroprogenic changes that have lead to a slow-down, warming and eutrophication of waterways. Many exotic species have large reproductive capacities and several have the ability to hybridize with the native fauna. Most successful, introduced exotics are armed with spines along their fin edges that make them resistant to predation, when compared to the soft-rayed native fauna. Exotic species have proved detrimental to some native fish species through competitive mechanisms, and exotic species have been consistently difficult to eradicate once self-sustaining populations become established.

The following accounts describe some of the geographic features of Columbia Basin and the 43 native and exotic fish species currently found within or recently extirpated from the Canadian portion of the Basin. The distribution maps were drawn from data and specimens housed at the Royal British Columbia Museum Ichthyological Collections. The Collections at the Royal British Columbia Museum are some of the oldest collection records in B.C., and these records have proven to be an excellent tool for assessing changes in fish distribution, community structure and species nomenclature. Additional distribution data was obtained from the University of British Columbia Ichthyological Museum.