Hydroelectric dams block salmon migration routes, causing exhaustion, injury, and death as fish attempt to navigate artificial barriers and unsuitable fish passes.
The physiological demands of salmon migration are already extreme - fish stop eating, burn enormous energy reserves, and navigate hundreds of kilometres to reach spawning grounds. Hydroelectric barriers add to this burden by forcing fish to repeatedly attempt passage through inadequate fish ladders or dangerous turbine zones. Each failed passage attempt depletes energy reserves needed for spawning. Dam removal programmes in North America and Europe have shown rapid and dramatic recovery in both salmon numbers and ecological function.