Understanding sea lice biology is essential for developing welfare-positive management strategies in salmon farming that address the underlying parasite rather than symptoms alone.
Sea lice cause progressive welfare harm through tissue destruction, secondary infection, osmotic stress, and immune suppression. The welfare impact scales with lice burden; threshold levels above which treatment is triggered represent a compromise between production and welfare costs. Preventive approaches that interrupt the lice life cycle before attachment — including deeper submersible pens, thermolicer management, and vaccine development — offer better welfare outcomes than reactive treatment after welfare harm has already occurred.