Salmon Lice Welfare and Treatment

Sea lice infestations in farmed salmon cause significant welfare harm and have been addressed through a range of treatments with varying welfare profiles.

Key Facts

Sea lice (Lepeophtheirus salmonis) cause open wounds on salmon skin and fins
Treatment methods include chemical bath treatments, mechanical removal, and cleaner fish
Hydrogen peroxide and azamethiphos bath treatments cause acute stress and mortality in some fish
Snorkel barriers and submerged feeding reduce lice exposure without treatment stress
Biological control using wrasse as cleaner fish raises welfare questions about wrasse themselves

Welfare Considerations

Sea lice management in salmon farming creates a welfare dilemma: lice infestations cause ongoing welfare harm, but the most common treatments cause acute stress and some mortality. The welfare calculus requires comparing chronic lice-caused suffering against acute treatment stress. Non-chemical prevention methods — barriers, submerged feeding, improved current management — address the problem without treatment stress. The welfare of cleaner fish like wrasse used for biological control is an often overlooked dimension of the problem.

What You Can Do

Support welfare standards for cleaner fish used in salmon farming
Advocate for non-chemical sea lice prevention as the preferred management approach
Choose salmon certified to lice management standards that minimize treatment stress
Donate to research into non-chemical lice prevention methods
Engage with the salmon-lice welfare tradeoff in discussions about salmon farming reform