Dams block migratory fish including salmon, shad, lamprey, and eel from reaching spawning habitat, causing population decline and the welfare impacts of disrupted migration drives in individual fish.
Key Facts
An estimated 60% of the world's major rivers are fragmented by dams, reservoirs, or diversions
Atlantic salmon runs have declined by over 50% in many European rivers since the industrial era
Fish passage facilities including fish ladders have limited effectiveness for some species including eels
Dam removal is increasingly recognized as the most effective restoration strategy where feasible
More than 1,000 dams have been removed in the US since 1990, with dramatic fish recovery following
European eel populations have declined by 95% since the 1970s partly due to turbine mortality
Welfare Considerations
Migratory fish welfare involves individual experiences of blocked migration drives — physiological states that impel upstream movement to spawning grounds. Fish attempting to pass barriers repeatedly expend energy and face exhaustion. Those killed in turbines die acutely. Those that cannot reach spawning habitat fail to reproduce after years of ocean growth. Dam removal provides direct individual welfare benefit to fish populations by restoring the habitat access that fish migration drives have evolved to seek. The scale of dam fragmentation globally makes restoration of fish passage one of the largest potential wildlife welfare improvements through infrastructure change.
What You Can Do
Support dam removal and fish passage programs in rivers with migratory fish populations
Advocate for fish passage requirements in dam relicensing processes
Choose hydroelectric power from facilities with documented fish passage effectiveness
Support organizations working on river connectivity restoration for migratory fish
Donate to eel conservation programs working on population recovery and migration barrier removal