The smolt stage in Atlantic salmon farming - the physiological transition from freshwater to saltwater - is a critical welfare period characterised by high stress, immune suppression and elevated mortality if not managed carefully.
The smolt transition is a physiologically vulnerable period when salmon are highly susceptible to stress-induced welfare deterioration. Management decisions made at this stage - timing of seawater transfer, transport conditions, stocking density at sea transfer - have welfare consequences that persist throughout the marine growing period. Poor smolt welfare correlates with higher sea lice burden, increased disease susceptibility and elevated mortality throughout the production cycle. Investing in smolt quality through optimal freshwater conditions, appropriate light management and careful transfer protocols is both a welfare and production efficiency investment.