Wild Salmon Migration Barriers and Welfare

How dams, agricultural diversions, and other human-made barriers affect wild salmon welfare, behavior, and population viability.

Key Facts

Over 1,000 dams block salmon migration routes in the western United States alone.
Salmon can attempt to pass fish ladders hundreds of times, expending critical energy reserves.
Water temperatures above 21 degrees Celsius cause physiological stress and mortality in Pacific salmon.
Agricultural water diversions can reduce river flows to levels too low for salmon passage.
Dam removal has led to rapid salmon recovery in rivers including the Elwha in Washington State.
Salmon provide nutrients to forest ecosystems by dying after spawning, fertilizing riverside vegetation.

Welfare Considerations

Individual salmon welfare during migration is difficult to assess but clearly significant. Fish approaching barriers repeatedly experience acute stress responses, including elevated cortisol, that deplete the energy reserves they need to spawn successfully. Thermal stress from warming rivers is increasingly severe as climate change progresses. Fish ladders help but do not fully replicate natural migration conditions, and many smaller fish fail to navigate them. Dam removal is the most effective long-term solution for salmon welfare and population recovery. In the interim, fish passage improvements, minimum flow requirements, and riparian temperature management through shade planting can meaningfully reduce welfare harms.

What You Can Do

Support dam removal initiatives that restore salmon migration routes on appropriate waterways.
Advocate for minimum flow requirements in agricultural water use agreements to protect salmon passage.
Plant native riparian vegetation to shade streams and reduce summer water temperatures.
Choose wild-caught salmon from well-managed fisheries with strong habitat conservation standards.