The transition of salmon smolts from freshwater hatcheries to marine net pens is a critical welfare event with significant mortality and stress implications.
Smolt sea transfer welfare represents a concentrated acute welfare event that sets the trajectory for individual fish welfare across the entire sea phase of production. Transfer at incorrect smoltification stages, under poor weather conditions, or through poorly managed pumping and transport creates stress responses that impair immune function and disease resistance for weeks after transfer. The welfare investment in optimal transfer timing and procedure quality has direct economic returns through reduced early mortality, creating alignment between commercial and welfare interests. Regulatory requirements for smolt quality documentation and transfer condition monitoring would institutionalize welfare-positive practices.