Fish Health Is Integral to Ecosystem Health

Fish, in their aquatic environment, are subjected to a wide variety of factors that determine their ability to grow, reproduce, avoid predation, and fight diseases. Yet the extent of their physiological and immunological adaptations to these constantly changing factors have received little attention. For example, the continuous influx of toxic chemicals into the aquatic environment has created situations where fish health has deteriorated due to immunosuppression, dysfunction of vital organs, and chromosomal aberrations. As a result, fish diseases and neoplasia often erupt in an epizootic manner. Moreover, in the globalization era, trade of live fish and their gametes has become unprecedented. Along with this international movement of fish, devastating pathogens spread into new areas, killing millions of native fish that had no immunity against the intruding pathogens. Federal and state natural resource agencies have initiated several rehabilitation programs that require keeping fish in higher densities in confined raceways. Unfortunately, this situtation increased the pathogenicity of certain microbes that would have otherwise been harmless. The development and implementation of effective fish health plans is necessary for the proper management of fisheries worldwide.