Disease outbreaks in aquaculture cause significant welfare harm and economic loss, and disease management approaches including vaccines, selective breeding and husbandry improvements offer more welfare-positive alternatives to chemical treatment.
Aquaculture disease management sits at the intersection of fish welfare, antibiotic stewardship and environmental sustainability. Disease outbreaks cause welfare harm through the illness itself — reduced feeding, behavioural changes, tissue damage and mass mortality. Treatment with chemicals and antibiotics adds further welfare costs through the treatment process and drug effects. Prevention through vaccination, genetic improvement and biosecurity is the most welfare-positive approach because it reduces both disease incidence and the need for welfare-costly treatment. The Norwegian salmon industry demonstrates that dramatic antibiotic reduction is achievable through vaccination without compromising production, providing a model for other aquaculture species and countries to follow.