The transition of salmon smolts from freshwater to seawater is one of the most physiologically demanding periods of their life, and managing this transition poorly has significant welfare and production consequences.
The smoltification process is one of the most significant welfare-relevant events in farmed Atlantic salmon production. When farms transfer fish to sea cages before the smolt window, the resulting physiological stress causes chronic welfare problems that can persist throughout the sea phase. Accurate assessment of smolt readiness using gill ATPase activity and condition indices is an important welfare tool that also serves production goals through improved survival rates. Water temperature management during the transition period is critical, as temperature extremes compound smoltification stress. Progressive salmon producers are investing in precise smoltification monitoring to optimize transfer timing, with benefits for both fish welfare and farm economics through reduced early mortality.