Migratory Fish and Dam Obstruction

Dams block fish migration, causing population-level welfare harm and stranding fish unable to complete their life cycles.

Key Facts

An estimated 60% of large river systems are fragmented by dams that block fish migration
Atlantic salmon populations have collapsed in rivers with impassable dams compared to free-flowing rivers
Fish at dam faces attempt to find passage and may exhaust themselves over days before dying
Fish ladders provide partial passage but are ineffective for many species and in high-flow conditions
Dam removal has restored salmon populations in rivers including the Elwha in Washington State within years

Welfare Considerations

Fish attempting to migrate past impassable dams experience prolonged exhaustion and failure over days as they search for passage that does not exist. The welfare harm is both acute — in the suffering of individuals unable to complete migration — and population-level, as reproductive failure compounds over generations. Dam removal is the most effective intervention for both welfare and conservation outcomes.

What You Can Do

Support dam removal and modification programs that restore fish passage on key migratory rivers
Advocate for fishway design standards that achieve meaningful passage rates for target species
Donate to river restoration organizations working on dam removal and fish migration recovery