How disease management in trout aquaculture affects fish welfare and the development of more humane prevention approaches.
Disease management in trout aquaculture involves a welfare calculus between prevention strategies with handling costs and treatment of established disease with more severe welfare impacts. The development of effective vaccination programs in Scandinavian aquaculture demonstrates that prevention through vaccination can dramatically reduce the need for antibiotic treatment while improving fish health and welfare outcomes. Disease outbreaks causing mass mortality represent the most severe acute welfare events in trout farming — affected fish experience prolonged illness before death. Welfare-progressive disease management prioritizes biosecurity to prevent pathogen introduction, vaccination where available and effective, early detection of emerging problems, and humane disposal of severely affected fish. The environmental cost of disease outbreaks — pathogen spillover to wild fish populations — adds a wild animal welfare dimension to farm disease management decisions.