Salmon hatcheries produce billions of fish for stocking and aquaculture, raising welfare questions about crowding, handling, and the transition to wild environments.
Hatchery salmon in crowded conditions experience chronic social stress and competition for resources. Handling during routine operations - sorting by size, marking with fin clips or tags, and transport - causes acute stress responses. Fish conditioned to hatchery environments may be poorly prepared for the challenges of wild survival. Predator conditioning programs that expose hatchery fish to predators improve post-release survival but involve controlled predation stress during conditioning. The welfare of billions of hatchery fish during their production phase deserves the same consideration as farmed fish, though the conservation purpose of hatchery programs adds complexity to welfare-commercial tradeoffs.