Fish Culture and Maintenance of Natural Life History Traits in Pacific Salmon

Anadromous stocks are traditionally cultured for harvest, but are occasionally taken into captivity to maintain local adaptive traits until factors contributing to the population’s natural decline are reversed.  In captivity these populations are at risk of unintentional domestic selection.  Theoretically, culturing captive populations in a natural manner should reduce the potential for domestication.  It may be possible to retain natural smolt and maturation age traits by rearing fish on natural temperature profiles and feed schedules.  Presenting feed as it is naturally found in time and space should favor the maintenance of wild competitive and social traits.   Rearing fish in freshwater or seawater as appropriate for their specific life history stage should aid in retaining anadromous traits.   Artificial spawning protocols should be designed to match the mean, range, and curve shape of natural spawning times and incorporate natural iteroparous and precocious maturation strategies.  Some captive fish should be allowed to spawn naturally to promote the maintenance of natural spawning and incubation behaviors.   The structure and current of artificial incubation and rearing environments should resemble the natural environment.   Although unintentional domestication can never be eliminated, these approaches may reduce the severity of its impact on captive populations to improve their reintroduction success.