Freshwater Fishes of the Columbia Basin Return to Table of Contents Return to Species List

Earlier this century there were few stigmas associated with the stocking of ponds, lakes and rivers with non-native fish species for food, sport, commercial or aesthetic reasons. Many of the western Canadian fish introductions were welcomed as a reminder of back home, and records indicate that exotic species such as Smallmouth Bass (Micropterus dolomieu) were introduced into Christina Lake (Kettle system) as early as 1901 (RBCM collection records). Today, attitudes have changed and we find that 37% (16 species) of the fish fauna in the Canadian portion of the Columbia Basin are non-native species (McPhail and Carveth 1992).

The majority of these introduced species thrive in the warmer waters of the lower Columbia, Kettle and Okanagan drainages. Some exotics such as Carp (Cyprinus carpio) and Goldfish (Carassius auratus) have large reproductive capacities that enable them to quickly outnumber the less fecund, but locally adapted, native fauna. Other exotic species from families Centrarchidae (Bass and Sunfish) and Percidae (Perch) are armed with spines along their dorsal surface and fin edges, making them resistant to predation when compared to the native soft-rayed fauna. Whatever the case, exotic species seem most suited to areas that have been influenced by anthroprogenic impacts associated with impoundment, agricultural use and urbanization (Dill and Cordone 1997; Nico and Fuller 1999; Gido and Propst 1999).

In addition to the introduction of non-native exotic species, many lakes, rivers and streams have been stocked with non-native, or semi-domesticated recreational species. Translocations of locally adapted species outside their original native habitat have been shown to alter the genetic integrity of wild, native faunal assemblages (Philipp et al. 1993; Billington and Herbert 1991). Rainbow Trout are native throughout most of British Columbia; however, the translocation of this opportunistic trout species has been detrimental to many Westslope Cutthroat Trout (Onorhynchus clarki lewisi) populations through mechanisms of displacement and hybridization. Most freshwater fish taxonomists agree that Char (Salvelinus) are notorious for their ability to hybridize and introgress among congeners (e.g. Baxter et al. 1997). Transplants of Lake Trout (Salvelinus nammaycush) and Eastern Brook Trout (Salvelinus fontinalis) have occurred in a number of Columbia Basin lakes and rivers in efforts aimed at diversifying recreational angling opportunities. Today we are noting the demise, and in some cases the eradication, of native Bull Trout (Salvelinus confluentus) populations as a result of such transplants (Donald 1993).