Hatchery production of salmon smolts for supplementation of wild populations involves welfare challenges that affect both hatchery fish survival and wild population outcomes.
Hatchery smolt welfare has both direct welfare implications for the billions of fish produced annually and indirect implications for wild salmon populations they are intended to supplement. Stressed, behaviorally naive hatchery smolts have poor survival after release — not just a production inefficiency but a welfare failure that ends in premature death for most released fish. Rearing conditions that reduce stress and improve behavioral competence through environmental enrichment and predator exposure produce fish that are both healthier during hatchery rearing and more capable of survival after release.