Wild Migratory Fish Welfare | Animal Welfare Hub

Migratory fish including salmon, eels, and sturgeon undertake epic journeys between freshwater and ocean, facing dams, fishing pressure, pollution, and climate change that block migrations and cause mass mortality.

Key Facts

Atlantic salmon populations in the UK and US have declined by over 50% since the 1980s due to multiple pressures on their migrations
Hydroelectric dams block migratory routes — fish ladders help some species but are ineffective for many and miss juvenile downstream migration
Wild salmon migrating through degraded rivers show physiological stress responses and higher mortality before spawning
Climate warming raises river temperatures above thermal tolerance thresholds during critical migration windows
Bycatch in open ocean fisheries captures millions of migratory fish annually as non-target species
Lamprey, once abundant, are blocked from upstream spawning habitat by dams and barriers across their entire historical range
Dam removal is the most effective single intervention for restoring migratory fish access to historical spawning grounds
European eel migration to the Sargasso Sea is now estimated to be completed by less than 10% of pre-industrial population levels

Welfare Considerations

The welfare of migratory fish is shaped by the cumulative gauntlet of stressors encountered across migrations of hundreds or thousands of kilometres. Each barrier — dam, pollution event, temperature extreme, fishing pressure — adds physiological stress that compounds through the journey. Salmon dying before reaching spawning grounds after surviving the ocean phase are experiencing welfare harms that accumulate across years. The mass mortality of spawning fish unable to complete their migrations represents suffering at enormous scale. Welfare and conservation priorities converge completely in the case of migratory fish: restoring free-flowing rivers, removing barriers, and reducing fishing pressure are simultaneously the most welfare-positive and conservation-effective interventions available.

What You Can Do

Support dam removal campaigns and river restoration projects that restore migratory fish access to historical habitat
Choose wild fish from fisheries with low bycatch of migratory species and with sustainability certification
Advocate for water temperature and pollution standards that protect migratory fish during critical migration windows
Support river land trust and riparian buffer programmes that reduce agricultural runoff affecting migration routes