Selective breeding for disease resistance in farmed trout offers one of the most promising pathways to reducing disease-related welfare burden at population scale. Understanding this research guides industry application.
Genetic selection for disease resistance represents a welfare advance that operates at the population level over generations — a different timescale from management interventions but with potentially transformative cumulative impact. Fish that are genetically less susceptible to major pathogens experience fewer episodes of clinical disease, less immune stress from subclinical infections, and lower mortality that removes the suffering of mass death events. The welfare benefit compounds across breeding generations as resistance alleles become more prevalent in the production population. Unlike management interventions that must be applied individually, genetic resistance confers protection automatically to every individual of the resistant line. Investment in welfare-relevant breeding objectives is therefore one of the highest-leverage welfare interventions available in aquaculture.