Possible Effects of Water Diversions on Fish Distribution in British Columbia

Abstract

The known distributions of freshwater fishes in drainages of the British Columbia mainland are summarized, including those of five species not previously recorded from the province. The continental divide forms a break in fish distribution; 35 of the 57 species on the Pacific slope in B.C. do not occur in the Mackenzie or Yukon River drainages of the province, and 11 of the 33 species in the latter area occur nowhere on the Pacific slope. Some proposed water diversions for hydroelectric development would cross the continental divide, and are likely to produce striking changes in fish distribution. A proposed Liard-Stikine diversion would probably introduce several species, including trout, into the upper Liard River, and several other species, including northern pike (Esox lucius) into the Stikine River. A proposed Peace-Fraser diversion would introduce into the Fraser River arctic grayling, and possibly several other species including northern pike. Other proposed diversions are discussed, and their probable affects on fish distribution are listed. Any diversion introducing pike into waters supporting Pacific salmon (Oncorhynchus) is liable to be economically harmful, as pike are voracious fish-eaters. Pike are also vectors of Triaenophorus tape-worm, which has been found in Alaska to encyst in the flesh of Pacific salmon in a watershed inhabited by pike.