Preference-avoidance responses of lake whitefish (Coregonus clupeaformis) to competing gradients of light and copper, lead, and zinc

The preference-avoidance responses of lake whitefish (Coregonus clupeaformis) to copper, zinc, and Pb ions were tested in a countercurrent trough that was either uniform in regard to illumination, or shaded in one half. Under uniform illumination, Cu was avoided at concentrations of 1 μg/L and higher, Zn and Pb at and above 10 μg/L. Fish preferred the shade when presented with a choice between shaded and illuminated. When metals were injected into the shaded, previously preferred area, avoidance of these ions was strongly suppressed, except for the highest concentrations, especially in the case of Pb.