Lethal Concentrations of Copper and Zinc for Young Atlantic Salmon

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Abstract
The toxicity of copper and zinc sulfates to immature Atlantic salmon (Salmo salar) was tested in soft water. The relation between concentration of metal and survival-time could be fitted by a straight line when logarithms were used. A sharp break in this relation marked the incipient lethal level, where survival became indefinitely long. Incipient lethal levels were 48 [mu]g/1 of Cu and 600 [mu]g/1 of Zn. In solution containing both Cu and Zn, fish died twice as fast as would occur if the 2 metals were simply additive in their lethal action. Resistance-times in zinc solutions were increased at pH 7.9-9.3, and results fitted the hypothesis that dissolved Zn was toxic, but not suspended Zn. Survival in a given concentration of Zn was 4 times as long at 5[degree] as at 15[degree]C, and the incipient lethal level was at least 1.5 times higher, with fish acclimated to each temperature.