Fish Migration Barriers and River Welfare

Dams, weirs, and other barriers prevent fish migration, disrupting spawning, feeding, and population connectivity with significant welfare consequences.

Key Facts

Over 1 million barriers to fish passage exist in European rivers, blocking migration routes
Atlantic salmon populations have declined dramatically in rivers where spawning access is blocked
Fish ladders can restore partial passage but many are poorly designed and few fish actually use them
Removing obsolete weirs and dams is increasingly recognised as the most effective restoration measure
Hydropower dams cause fish mortality through turbine passage, pressure changes, and thermal stratification
Migratory fish that cannot reach spawning grounds experience reproductive frustration and physiological stress
Dam removal projects in Europe and the US have shown rapid fish population recovery

Welfare Considerations

For migratory fish species, barriers represent welfare harms at multiple levels. Individual fish experience the acute frustration of attempting to pass impassable barriers, expending energy and experiencing stress in attempts to overcome obstacles to spawning migration. The physiological drive to migrate is strong, and the inability to fulfil this drive is likely to involve something analogous to chronic frustration. Beyond individual welfare, populations cut off from spawning grounds decline, meaning the welfare harm scales to all future generations prevented from completing their life cycle. River restoration through barrier removal addresses these welfare harms directly, reconnecting habitats and allowing fish to fulfil natural migration patterns that have evolved over millions of years.

What You Can Do

Support river restoration organisations working on barrier removal and fish passage improvement
Advocate for removal of obsolete or low-value dams and weirs that block fish migration
Oppose new hydropower or water management infrastructure that would create additional barriers
Support research into improved fish passage design for barriers that cannot be removed
Engage with water management policy consultations to ensure fish welfare is included in decision-making