The transfer of juvenile salmon (smolts) from freshwater hatcheries to sea cages is a critical welfare risk point. Timing, handling, and transport conditions determine welfare outcomes.
The smolt transfer represents one of the highest-risk welfare events in the salmon production cycle. Smolts undergo profound physiological changes during smoltification, and their stress tolerance is reduced during this period. Handling, temperature changes, and crowding during transfer all impose welfare costs on animals already physiologically challenged. Poorly timed transfer — before or after the smoltification window — can cause mass mortality. The welfare-positive approach uses physiological indicators to confirm smoltification status, minimises handling duration, maintains appropriate temperature and oxygen during transport, and deploys fish rapidly after transfer to minimise additional stress.