Breeding for chemical camouflage the case of salmon kairomones and resistance to salmon lice infectivity

Abstract Salmon lice are ectoparasites that threaten wild and farmed salmonids. Artificial selection of salmon for resistance to the infectious copepodid lice stage currently relies on in vivo challenge trials on thousands of salmon a year. We found that salmon emit a bouquet of kairomones which the lice use to find and infect the salmon. Some of these compounds vary between families and could be used as a more direct and ethical measurements of lice resistance for breeding farmed salmon.