Atlantic salmon is the most economically valuable farmed fish globally, and welfare science for this species is the most advanced in aquaculture, yet significant welfare challenges remain in commercial production.
Farmed salmon welfare research is more advanced than for any other fish species, yet significant welfare problems persist at commercial scale. Sea lice cause chronic irritation and tissue damage across millions of fish simultaneously. Treatment methods — chemical baths, mechanical delousing, and biological controls using cleaner fish — all carry welfare costs. High stocking densities cause chronic social stress and fin damage from aggression. The stress of crowding during feeding, sorting, and treatment events compounds baseline welfare challenges. The welfare of cleaner fish (wrasse and lumpfish) used to control sea lice has itself become a significant concern, adding another welfare dimension to salmon farming. Progress is being made through welfare-based regulation, continuous monitoring technology, and breeding for disease resistance.