Sea Trout Welfare: Migratory Salmonids Under Compound Pressure

Sea trout are migratory brown trout that travel to sea to feed before returning to freshwater rivers to spawn. Their welfare is challenged by sea lice from salmon farms, river barriers, and habitat degradation.

Key Facts

Sea trout are migratory forms of brown trout that enter the sea to feed and grow before returning to spawn
They are particularly susceptible to sea lice infestation, amplified by proximity to salmon farms
Sea lice from fish farms affect wild sea trout smolts in nearshore waters, causing lethal infestations
River barriers including weirs and culverts prevent sea trout from accessing upstream spawning grounds
Scottish and Irish sea trout populations have declined dramatically in regions adjacent to salmon farms

Welfare Considerations

Sea trout face welfare harm at every stage of their complex life cycle. Smolts migrating to sea encounter amplified sea lice populations near fish farms, causing infestations that can be lethal. Returning adults face river barriers, low flows from abstraction, and spawning habitat degraded by siltation. The combination of marine and freshwater threats means no single intervention is sufficient. Reducing sea lice from salmon farms — through improved farm management or relocation — would be the most impactful single welfare improvement for sea trout.

What You Can Do

Support campaigns for improved sea lice management standards on salmon farms near sea trout rivers
Back river barrier removal projects that open upstream migration routes for sea trout
Donate to organisations monitoring sea trout populations in affected rivers
Reduce farmed salmon consumption to create market pressure for improved sea lice management