Salmon lice (L salmonis) can quickly adapt to new challenges, as the salmon aquaculture industry has discovered over the past decades. Many chemicals used to treat lice-infested salmon have become ineffective, due to lice evolving pesticide resistance. As new pesticides and other treatments become available to farms, it is crucial that the industry considers whether resistance could arise, and what actions farms can take to prevent this from happening. For this, a better understanding of how pesticide resistance grows and spreads across a network of salmon farms is required.