Acute toxicity of a zinc-polluted stream to four species of salmonids

Four species of salmonids were exposed to different dilutions of water from a stream polluted by zinc. Test duration was 14 days for all species. The TL₅₀ for rainbow trout (Salmo gairdneri) was 0.41 mg zinc/ liter. TL₅₀ values for zinc to brown trout (Salmo trutta), cutthroat trout (Salmo clarki), and brook trout (Salvelinus fontinalis) were 0.64, 0.67, and O.96 mg/liter, respectively. Rainbow trout were least tolerant of zinc and brook trout were the most tolerant. Cutthroat trout were considered more susceptible to zinc than brown trout.