Pacific salmon undergo one of nature's most dramatic biological transformations as they migrate from ocean to freshwater spawning grounds. Understanding the welfare dimensions of this extraordinary process informs management of their habitats and populations.
The spawning migration of Pacific salmon involves physiological processes that are extraordinary from a welfare perspective. The post-spawning death of Pacific salmon is genetically programmed rather than caused by exhaustion — a distinction with philosophical implications for how we understand the welfare dimensions of this natural process. However, the conditions under which modern salmon complete their migrations are increasingly compromised by human activity. Dam barriers require fish ladders or trucks to bypass; water temperatures elevated by climate change and water withdrawal cause physiological distress and immune compromise; pollution impairs navigation. The welfare question is not whether salmon should die after spawning — that is their evolved biology — but whether humans are creating conditions that cause excess suffering during migration through habitat degradation.