Salmon demonstrate complex behaviors indicating sentience and capacity for suffering, with welfare relevant to both wild populations facing migration barriers and farmed fish in aquaculture systems.
The welfare case for salmon is grounded in their demonstrated nociception and stress physiology. Sea lice infestations - a severe problem in open net pen aquaculture - cause tissue damage and behavioral distress comparable to other parasitic infections in vertebrates. Crowding prevents the full expression of salmon movement patterns, territories, and escape responses. Wild salmon migrations through warming, low-oxygen rivers represent a gauntlet of physiological stress. Welfare-positive approaches include lower stocking densities, closed containment systems that prevent sea lice exchange, and watershed restoration that improves wild salmon migration conditions.