The freshwater hatchery and smolt production phases of Atlantic salmon farming have distinct welfare challenges requiring management appropriate to each developmental stage.
Freshwater phase welfare in salmon farming sets the foundation for fish health and welfare throughout the production cycle. Hatchery conditions including water quality, stocking density, feed management and disease control in the freshwater phase affect the physiological state of fish entering the sea. Smoltification is a welfare-sensitive period when fish are physiologically transformed for seawater - stress during this phase can compromise the transformation and create welfare problems in the sea. Welfare-focused freshwater phase management uses monitoring of smoltification indicators to determine optimal transfer timing.