Laser systems that target and kill individual sea lice on salmon are increasingly deployed as an alternative to chemical and thermal treatments. Their welfare impact is a subject of active research.
Laser systems represent a genuine welfare improvement compared to thermolicer bathing that causes thermal shock and physical damage. Startle responses to laser pulses suggest some acute experience, but evidence suggests this is substantially less stressful than alternative treatments. Welfare assessment must compare options rather than judge laser treatment in isolation.