Selective breeding in salmon aquaculture has focused primarily on growth rate, but genetics also influences welfare-relevant traits including disease resistance, behavioral responses, and stress coping styles.
Salmon genetics and welfare are deeply intertwined — the selective breeding decisions made by aquaculture companies over decades have created fish phenotypes with welfare trade-offs that cannot be reversed without deliberate genetic management. Extreme growth rate selection has been associated with cardiovascular dysfunction, skeletal abnormalities, and cataracts in some lines — welfare problems built in at the genetic level. The positive opportunity exists to actively select for welfare-beneficial traits: disease resistance reduces the frequency of infections and treatments, stress coping style affects behavioral responses to handling and crowding, and behavioral traits related to aggression influence conspecific injury rates. Breeding programs that expand selection criteria beyond growth and feed conversion to include welfare indicators represent a promising pathway to systemically improving farmed salmon welfare at scale. This complements — and provides longer-lasting solutions than — purely management-based welfare improvements.