How selective breeding in farmed salmon affects welfare outcomes, the tradeoffs between productivity traits and health, and emerging research into welfare-positive genetic selection.
Salmon genetics represents a powerful but underutilized lever for welfare improvement in aquaculture. The selective breeding programs that created modern farmed Atlantic salmon optimized heavily for growth rate — producing fish that grow dramatically faster than wild counterparts but with associated welfare costs including higher rates of spinal deformity, cataracts, and cardiovascular problems linked to rapid muscle development. This mirrors the welfare crisis in broiler chickens, where growth-focused selection created animals with bodies mismatched to normal physiology. However, genetics also offers welfare solutions: selective breeding for disease resistance has successfully produced salmon lines that develop fewer lice and bacterial infections, directly reducing suffering without pharmaceutical intervention. Breeding for reduced stress cortisol responses is more complex — domestication has already reduced acute stress responses, but whether this represents genuine welfare improvement or merely suppressed behavioral signaling of underlying distress is scientifically unresolved. Future genetic selection for farmed salmon welfare requires explicitly including welfare traits — spinal health, eye health, disease resistance, thermal tolerance — alongside production metrics.