Wild salmon face extraordinary mortality during ocean phases of their lives. Understanding ocean survival factors matters for both conservation and welfare.
Salmon endure extreme physiological stress during migration, spawning, and senescence. For anadromous species that die after spawning, this represents an evolutionary trade-off rather than welfare concern. However, human-caused stressors — thermal pollution, bycatch, reduced prey availability, and dam barriers — impose additional suffering and mortality beyond what salmon have evolved to cope with. Dam-related passage injuries, entanglement in fishing gear, and warm water stress are welfare issues that intersect with conservation priorities.