The freshwater phase of salmon smolt production involves specific welfare challenges related to crowding, feeding management, and the physiological changes of smoltification.
Freshwater smolt production welfare is determined by the quality of management during a physiologically sensitive developmental period. Smoltification involves dramatic changes to osmoregulatory physiology, behavior, and appearance — the fish are fundamentally changing to prepare for a different environment. Stress during this period impairs the physiological transformation and has lasting welfare and production consequences. Best practice management minimizes crowding, maintains optimal water conditions, and uses photoperiod manipulation that achieves production goals while respecting welfare implications of light manipulation on fish behavioral patterns. The quality of the freshwater phase shapes the welfare of salmon throughout their entire sea cage life.