Crowding in salmon aquaculture creates social stress, competition injuries, and suppressed behavior that are measurable welfare problems — stocking density standards are among the most important welfare regulations in salmon farming.
Stocking density is among the most directly controllable determinants of salmon welfare in aquaculture settings. Crowded fish cannot express normal swimming behavior, face constant competitive pressure for preferred positions in water currents, and experience elevated cortisol that suppresses immune function and compromises their ability to maintain health. The economic pressure to maximize the number of fish per unit of water cost cuts against welfare interests in a direct trade-off that requires regulation or consumer pressure to resolve. Welfare certification standards that specify maximum stocking densities with monitoring requirements provide the external pressure needed to maintain welfare-protective densities.