Salmon and trout spend their early lives in hatcheries before transfer to grow-out sites. Welfare conditions in hatcheries significantly affect the health and wellbeing of fish throughout their production lives.
Hatchery welfare is the foundation of salmon and trout welfare outcomes across the production cycle: fish that experience chronic stress in early development have altered stress responsiveness, impaired immune function, and reduced resilience to the challenges of grow-out. Key welfare concerns include: stocking density that exceeds the carrying capacity of water quality systems; handling for grading and vaccination without adequate anaesthesia; and management of the smoltification process that is inadequately timed or stressful. The welfare of hatchery fish receives less attention than grow-out welfare because the fish are smaller and less economically valuable individually — but the population-level welfare impact is enormous given the numbers involved. Improving hatchery welfare is also a production quality investment: resilient, low-stressed smolts perform better at sea.