Enriched rearing environment and wild genetic background can enhance survival and disease resistance of salmonid fishes during parasite epidemics

The importance and volume of aquaculture is increasing world-wide. Rearing practices play a key role in determining growth rate, survival and disease resistance in aquaculture fishes. Recent evidence suggests that in comparison with a standard stimulus-poor rearing environment, an enriched or variable rearing environment has significant positive effects on several traits underlying growth and well-being of fish. However, the effect of enriched rearing on one of the most important threats for aquaculture development, occurrence of parasitic infections, remains unknown. We used surveillance data of experimental salmonid populations of wild and hatchery origin under semi-natural parasite exposure to explore effects of enriched rearing on outbreaks of important aquaculture pathogens and associated fish mortalities in production-scale fish densities. We also conducted controlled parasite exposures to investigate if enriched rearing reduces susceptibility of fish to infection in comparison wi...