Pacific salmon populations are experiencing dramatic declines across their range due to a combination of habitat loss, overfishing, climate change, and hatchery impacts, with individual welfare consequences at each stage.
Pacific salmon welfare is inextricable from the ecological crisis affecting their populations. Individual fish that survive ocean feeding to begin the spawning migration encounter a series of welfare challenges that have intensified with climate change and habitat degradation. Warm river temperatures cause physiological stress, impaired oxygen uptake, and increased vulnerability to disease; blocked passages cause exhaustion and increased mortality; and the density-dependent effects of degraded habitat mean more competition for spawning habitat and rearing space. Climate-driven changes to river temperature regimes are making some rivers unsuitable for salmon during historical migration periods. The welfare case for Pacific salmon conservation is aligned with and reinforces the ecological case: restoring free-flowing, cool rivers benefits both the population and the individual fish within it.