Dams and Salmon: How Barriers Disrupt Spawning Runs and Welfare

Hydroelectric and irrigation dams fragment salmon rivers, blocking spawning migrations and causing physiological stress and mass mortality in affected populations.

Key Facts

Salmon must swim hundreds of kilometres upstream to spawn, a journey blocked by many dams
Adult salmon attempting to pass unladdered dams sustain physical injury and lethal energy expenditure
Fish ladders help passage but are often inefficient, especially for weaker or older individuals
Smolts migrating downstream face blade strike injuries from turbines at hydroelectric facilities
Dams alter water temperature and flow, degrading spawning habitat even when passage exists
Dam removal has restored salmon runs dramatically in rivers across the US and Europe
Atlantic salmon populations have declined by over 70% in the last 25 years, partly due to barriers

Welfare Considerations

Dams inflict cumulative welfare harm on salmon across their entire life cycle. Juveniles face turbine strike and disorientation in reservoirs during downstream migration. Adults experience extreme physiological stress — including cortisol surges, muscle depletion, and immune suppression — when blocked from reaching spawning grounds. Fish that cannot spawn die without reproducing, representing both an individual welfare and population conservation failure. The welfare case for dam removal or bypass channels aligns with ecological restoration goals, making it an area where welfare and conservation advocacy can be mutually reinforcing.

What You Can Do

Support campaigns for dam removal or modernisation of fish passage infrastructure
Choose electricity providers committed to low-impact hydropower with fish-friendly turbines
Advocate for mandatory fish passage assessments before new dam approvals
Support wild salmon conservation charities working on barrier removal