Atlantic salmon are the most studied farmed fish for welfare, yet significant challenges remain. Crowding stress, fin damage from aggression, and sea lice infestations affect millions of salmon daily in net pen operations.
Salmon welfare in net pen aquaculture represents a massive welfare challenge at scale. The combination of high stocking densities causing chronic crowding stress, sea lice infestations causing skin and tissue damage, and management procedures including crowding for treatments all contribute to welfare deficits. The welfare of cleaner fish added to pens to control lice is an emerging concern - wrasse and lumpfish have their own welfare needs including species-appropriate diet, shelter, and water temperature that are often inadequately met. Mortality rates of 15-20% indicate a significant proportion of fish experience welfare problems serious enough to cause death. Consumer demand for certified welfare salmon has driven measurable improvements in Norway's dominant industry.