Sea lice treatments in Atlantic salmon farming, including warm water bath treatments and mechanical delousing, cause significant acute stress and mortality that must be weighed against the welfare benefits of lice control.
Lice treatment welfare involves acute treatment stress versus chronic disease welfare. Poorly planned treatments at wrong water temperatures or in fish with high lice loads can cause significant mortality. Treatment frequency is driven by lice targets that may be set too low to provide adequate treatment intervals for recovery. The welfare optimum requires balancing both acute and chronic stressors.