Sea lice treatments in salmon farming, from chemical baths to thermal treatments, raise significant welfare concerns for the fish being treated.
Thermal delousing exposes salmon to extreme temperature shocks that cause acute stress, tissue damage, and mortality particularly in already stressed or diseased fish. High-pressure mechanical treatments cause scale loss and wounds. Chemical treatments cause toxicity effects and oxygen depletion. The cumulative welfare burden of repeated treatments throughout a production cycle is significant. Preventative approaches including cleaner fish, enclosed cages, and genetic resistance are preferable welfare outcomes.