Crowding in salmon net pens causes chronic stress that impairs immune function, behavioral expression, and overall welfare. Understanding crowding thresholds and behavioral indicators guides welfare-positive management.
Salmon crowding represents a chronic welfare compromise in mainstream aquaculture driven by the economics of maximizing production per volume of water. The physiological consequences - chronic stress activation, immune suppression, and disease vulnerability - are measurable and have been well-documented in welfare research. The alignment between lower density and better feed conversion efficiency means there is some commercial incentive to manage crowding, but this incentive is insufficient to drive welfare-positive densities without regulatory floor requirements. Certification schemes that set maximum stocking densities provide the market signal needed to reward producers who invest in lower-density, higher-welfare systems.