Salmon hatcheries produce billions of juvenile fish for aquaculture and wild population supplementation, with welfare implications across multiple life stages.
Hatchery welfare spans the full developmental arc from egg through smolt, with different welfare priorities at each stage. Egg welfare depends on water quality management and avoidance of mechanical damage. Larval and juvenile welfare is most affected by stocking density, which influences aggression, fin erosion, and chronic stress. Vaccination and grading procedures impose acute stress that can be minimized through optimized handling protocols, anesthesia use for extended procedures, and post-handling recovery periods. Welfare across the hatchery life stage affects both the wellbeing of individual fish and the survival and behavior of released fish.