Repeated antipredator conditioning: a pathway to habituation or to better avoidance ?

Hatchery-reared juveniles of Arctic charr Salvelinus alpinus were conditioned to the odours of Arctic charr-fed pikeperch Sander lucioperca in the absence of any other cues. Accordingly, there was no physical threat of capture for the Arctic charr. It was evident from the subsequent survival tests that a single exposure to predator odours was enough to increase Arctic charr survival compared to predator-naive control fish whist under direct threat from live predators. Instead of habituating to predator odours, the fish conditioned repeatedly (four times) improved their spatial avoidance of predator cues in the course of training. The repeated conditioning also further enhanced the survival of the test fish as compared to the singly conditioned fish. The economical and ethical advantages of training with chemical cues, combined with its high reliability, could promote the success of fish reintroductions especially through repeated antipredator conditioning. (c) 2006 The Fisheries Society of the British Isles.