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

The preference-avoidance responses of lake whitefish (Coregonus clupea formis) to Cd were measured following 3 weeks exposure to water contai ning 0, 0.2, 1, or 5 mug Cd/L. Fish movements were tracked in a counte rcurrent-type trough with clean water on one side, and water containin g sequentially increasing Cd concentrations (0-25 mug/L) on the other. While fish not previously exposed to Cd showed a weak attraction to t he highest test concentration only, those pre-exposed to 5 and 1 mug/L Cd were subsequently attracted to water containing Cd at the same con centration to which they had been previously exposed. This response wa s 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 impa rts an odor or flavor which previously exposed whitefish will seek out . The possible implications of such attraction responses in field situ ations are discussed.