Understanding how the Hatchery Environment Represses or Promotes the Development of Behavioral Survival Skills

Although great strides have been made in the development of techniques for rearing marine fish, methods for improving survival capabilities following release of these fish into the natural environment have not kept pace. Most responsible for impeding progress has been the lack of adequate knowledge of the complex interactions between a species and the myriad physical and biological factors a hatchery fish faces upon release. Being reared in the psychosensorily deprived environment of a hatchery may lessen the innate capability of fish to carry out the basic survival strategy of all fish: to eat and not be eaten. In this synthesis we focus on some of the key behaviors that play a role in predator avoidance and food acquisition and on how the rearing environment may affect the expression of these behaviors. One of the major causes of mortality in hatchery- reared fish is predation, much of which occurs shortly after release. Available evidence seems to indicate that antipredator behavior in hatchery-reared fish is not fully developed. Possible deficits may also occur in feeding after release, when fish are faced with the shift from hatchery-supplied foods to the capture of live prey. Added to possible hatcheryinduced deficits in behavior are the alterations in behavior that may result from the stress of handling and transportation. Behavioral capabilities in hatchery-reared fish can be improved in a number of ways, including exposure to predators or predatory stimuli, alteration of spatial and temporal distribution of food, mitigation of rearing and transport stress, and control of the social environment.