Salmon aquaculture stocking densities affect fish welfare through crowding stress, injury risk, and behavioral restriction. Evidence-based density limits are central to welfare certification.
Salmon stocking density is a central welfare parameter because crowding simultaneously affects multiple welfare dimensions: behavioral restriction, social stress, injury rates, disease susceptibility, and oxygen competition. The evidence that salmon prefer lower densities when given choice provides a clear welfare signal. Certification standards that set density limits below regulatory minimums create market incentives for better practice. The crowding that occurs during sea lice treatments - when predator exclusion nets shrink effective cage volume - represents acute welfare episodes within an already stressful production system. Welfare-positive salmon farming requires density management throughout the production cycle.