Migratory Fish Ladders and Fish Welfare

Fish ladders and bypass channels help migratory fish navigate past dams and weirs, reducing welfare harms from blocked migration routes and supporting population recovery.

Key Facts

An estimated 2 million dams and weirs block river migration routes in the US alone
Fish ladders were developed in the 19th century and vary enormously in effectiveness
Poorly designed ladders may pass fewer than 10% of approaching fish, while good designs pass 90%+
Atlantic salmon and Pacific salmon species have declined dramatically due to migration barriers
Alternative designs including bypass channels and nature-like fishways outperform traditional fish ladders

Welfare Considerations

Fish blocked from migrating to spawning grounds experience welfare harms through frustrated behavior and ultimately reproductive failure. When dams cannot be removed, well-designed fish passage infrastructure reduces these welfare harms by restoring access to essential habitat. The welfare benefit of effective fish passage extends across the entire migration route, affecting populations from juveniles moving downstream to adults returning to spawn. Monitoring passage effectiveness is essential — non-functional fish ladders provide false assurance without welfare benefit.

What You Can Do

Support dam removal advocacy where ecologically and economically feasible
Advocate for fish passage monitoring requirements on all existing river barriers
Donate to organizations designing and building nature-like fishways in high-priority rivers
Engage with water authorities about fish passage effectiveness monitoring requirements
Learn about local migratory fish species and the barriers they face in your watershed