INFLUENCE OF CADMIUM PREEXPOSURE ON THE PREFERENCE-AVOIDANCE RESPONSES OF LAKE WHITEFISH (COREGONUS-CLUPEAFORMIS) TO CADMIUM

The preference-avoidance responses of lake whitefish (Coregonus clupeaformis) to Cd were measured following 3 weeks exposure to water containing 0, 0.2, 1, or 5 mug Cd/L. Fish movements were tracked in a countercurrent-type trough with clean water on one side, and water containing sequentially increasing Cd concentrations (0-25 mug/L) on the other. While fish not previously exposed to Cd showed a weak attraction to the highest test concentration only, those pre-exposed to 5 and 1 mug/L Cd were subsequently attracted to water containing Cd at the same concentration to which they had been previously exposed. This response was most pronounced among fish preexposed to 5 mug/L, which displayed a relatively strong attraction to water containing 5 mug/L when compared to responses to other test concentrations. This suggests that Cd imparts an odor or flavor which previously exposed whitefish will seek out. The possible implications of such attraction responses in field situations are discussed.