Innate predator recognition in newly-hatched Atlantic salmon

It is well established that fish can learn to associate odours from potential predators with risk and alter their behaviour accordingly. However, newly-hatched individuals have few opportunities for acquired predator recognition and may depend on unlearnt (innate) responses. We therefore considered whether newly hatched Atlantic salmon fry (alevins) exhibit innate predator recognition and whether this recognition could be improved by prior exposure to combined conspecific and predator (pike) odours. Our investigation showed that the response to pike odour was not affected by previous exposure to pike odour and conspecific tissue extract but was consistent with innate recognition of pike as predators. Trials conducted using odour from a non-piscivorous species confirmed that the fish were not simply reacting to a novel stimulus.