Life Skills for Hatchery Fishes

Social learning of Life skills in hatchery-reared fish

Objective: Our research is aimed at improving the post-release survival of hatchery-reared fish by training them to accept live food items and recognise predators. We compare a number of different training techniques including testing fish alone, in naïve pairs, and in pairs containing knowledgeable individuals (demonstrators). Training fish with demonstrators is far more efficient than any other technique because fish are able to learn more rapidly by observing others (social learning). in this way they develop the necessary skills much more quickly than single fish or groups of naïve fish.

Justification: The world’s fish species are under threat from habitat degradation and over exploitation. In many instances attempts to bolster stocks have been made by rearing fish in hatcheries and releasing them into the wild. Fisheries restocking programs have primarily headed these attempts. However, a substantial number of endangered species recovery programs also rely on the release of hatchery-reared individuals to ensure long-term population viability. Fisheries scientists have known about the behavioural deficits displayed by hatchery-reared fish and the resultant poor survival rates in the wild for over a century.  Around 97% of all hatchery rear fish die before reaching adulthood. Whilst there remain considerable gaps in our knowledge about the exact causes of post-release mortality, or their relative contributions, it is clear that significant improvements could be made by rethinking the ways in which hatchery fish are reared, prepared for release and eventually liberated. We emphasise that the focus of fisheries research must now shift from husbandry to improving post-release behavioural performance. Conservation reintroduction techniques including environmental enrichment, life skills training, and soft release protocols could be implemented by hatcheries with relative ease and could potentially provide large increases in the probability of survival of hatchery-reared fish. Several of the necessary measures need not be time-consuming or expensive and many could be applied at the hatchery level with out any further experimentation.