Aquaculture

Sea Lice Welfare in Salmon Farming

Sea lice are parasitic copepods that cause serious welfare problems in farmed Atlantic salmon and affect wild salmon populations near farms.

Key Facts

Sea lice attachment causes skin lesions, scale loss, and osmoregulation failure
A single adult female sea louse produces over 1,000 offspring
Treatments include chemical bath treatments, lasers, and cleaner fish
Cleaner fish (wrasse and lumpfish) are used in 50% of Norwegian salmon cages
Wild salmon smolts near farms experience elevated lice loads

Welfare Considerations

Sea lice infestations cause painful lesions and secondary infections. Skin damage impairs the salmon's ability to regulate salt and water balance. Mechanical lice removal treatments (Hydrolicer, Thermolicer) cause acute stress and physical damage, with documented mortality. Chemical treatments stress fish and may cause liver damage. Cleaner fish welfare is frequently poor - high wrasse mortality rates in cages are documented.

What You Can Do

Choose land-based aquaculture salmon products where available
Ask retailers about sea lice management practices
Support research into biological sea lice control with good wrasse welfare
Advocate for closed-containment salmon farming systems
Back Norwegian and Scottish farm siting regulations that protect wild salmonid rivers