Salmon hatchery supplementation programs raise complex welfare questions for both hatchery-reared fish and wild populations whose genetic integrity and behavioral fitness can be affected.
Hatchery supplementation involves welfare trade-offs across both individual and population levels. Hatchery-reared fish released into wild environments experience higher mortality than wild fish partly due to behavioral deficits from hatchery conditions. Reforms including predator conditioning, reduced density, and environmental complexity improve hatchery fish behavioral welfare and post-release survival simultaneously. These welfare improvements also reduce the genetic impact on wild populations by producing more behaviorally competent fish.