Fish Migration Barriers and Freshwater Fish Welfare

Dams, weirs, and culverts block fish migration routes, causing population declines and significant welfare impacts on individual fish stranded or exhausted by barriers.

Key Facts

Over 1 million dams and weirs exist on European rivers alone
Atlantic salmon populations have declined 70% in the past 25 years partly due to barriers
Fish passes allow migration at only 40-60% efficiency compared to free-flowing rivers
Fish exhausted at barriers are more vulnerable to predation, disease, and starvation
Dam removal has proven the most effective conservation intervention for migratory fish

Welfare Considerations

Migration barriers cause welfare harm at the individual fish level: fish attempting to pass impassable barriers experience exhaustion, physical injury from repeated attempts, and stress from crowding. Salmon and other migratory species have evolved compulsive migratory drives that cannot be suppressed — they will injure themselves attempting to pass barriers. Beyond individual welfare, population-level declines mean billions of fish never complete their life cycles. Dam removal and fish pass installation are proven interventions that restore individual welfare and population health simultaneously.

What You Can Do

Support river restoration organizations working on dam removal and fish pass installation
Advocate for fish passage requirements in water infrastructure permitting
Reduce electricity use to decrease pressure for hydroelectric dam construction
Choose sustainably certified fish that supports watershed conservation programs
Volunteer with river monitoring groups that track fish population recovery