Salmon hatcheries supplement declining wild populations but raise welfare questions about the conditions fish are kept in before release and the welfare of fish in the wild after hatchery release.
Salmon hatchery welfare involves multiple overlapping concerns: the welfare of fish during their hatchery period, the welfare implications of release into conditions many are poorly equipped to survive, and the population-level welfare of wild salmon whose genetic fitness may be reduced by hatchery interbreeding. Fish kept in high-density hatchery conditions without enrichment experience chronic crowding stress and are exposed to disease at rates that would not occur in natural conditions. When these fish are released with poor predator avoidance behaviors and reduced fitness, many die quickly - a welfare outcome that questions whether the supplementation program serves the fish's interests or primarily human fishery interests. Conservation hatcheries using lower densities and behavioral conditioning have better welfare and post-release survival outcomes.