Sea lice infestations represent one of the most serious welfare and production challenges in Atlantic salmon aquaculture. Emerging biocontrol methods offer alternatives to chemical treatments with improved welfare outcomes.
Sea lice infestations cause genuine suffering in farmed salmon. The parasites feed on skin, mucus, and blood, causing open wounds that become infected, chronic pain signals, and systemic stress responses including elevated cortisol. The welfare impact is compounded by the treatments themselves: chemical baths cause respiratory distress and thermal stress. Cleaner fish used as biocontrol agents also raise welfare concerns — wrasse in particular have high mortality rates in salmon cages and may experience significant stress and injury. Genuinely high-welfare sea lice management requires a systems approach: closed containment or semi-enclosed systems that prevent infestation, combined with non-invasive monitoring and the least harmful treatment options when infestations occur.