High stocking densities in salmon net pens cause chronic stress, aggression, and disease — welfare science is defining optimal density thresholds for commercially viable high-welfare production.
High stocking density is one of the most significant welfare challenges in salmon farming. Crowded fish show elevated stress hormones, increased fin damage from aggression, and higher susceptibility to disease. Optimal density depends on water temperature, oxygen, and flow rate. Welfare-focused producers are demonstrating that lower density production is commercially competitive when premium welfare certification is obtained.