Selective breeding of Atlantic salmon for resistance to sea lice infestation offers a welfare-positive alternative to treatments, addressing the root cause of a major aquaculture welfare problem.
Sea lice resistance breeding represents a systemic welfare improvement that addresses the cause of infestation rather than managing its consequences. Current lice management relies heavily on treatments, both chemical and mechanical, that themselves cause welfare compromise through acute stress and injury. A salmon line with significantly reduced lice susceptibility requires fewer treatments, spends more time at low lice burden, and avoids the repeated treatment stress that conventional management involves. The approach requires sustained investment in breeding infrastructure and challenge testing but produces lasting genetic improvements that propagate through the production system. Combining resistance genetics with other management tools including fallowing, lice monitoring, and selective deployment of cleaner fish offers the most comprehensive welfare-positive approach to lice management currently available.