The hatchery phase of Atlantic salmon production is critical for fish welfare, as early-life stress, crowding, and handling practices influence health and behavioural outcomes across the entire production cycle.
Welfare in salmon hatcheries is shaped by factors that are often invisible to outside observers but profoundly influence the fish that emerge from them. High densities restrict normal behaviour and increase competition for resources; repeated handling for grading and vaccination causes acute stress responses that, when repeated, can impair immune function and alter stress physiology in ways that persist through the sea-water phase. The smoltification window is particularly sensitive — fish undergoing this transformation are highly responsive to environmental conditions, and poor management during this period can produce smolts with compromised welfare outcomes in sea cages. Investment in lower-density rearing, refined handling techniques, and environmental enrichment such as water current and substrate complexity represents the frontier of hatchery welfare improvement. The long-term commercial benefits of producing robust, healthy smolts align well with welfare goals.