IDENTIFICATION OF SUCCESS FACTORS FOR ANTIPARASITIC TREATMENTS AGAINST THE SALMON LOUSE Caligus rogercresseyi THROUGH AN EXPERT PANEL

The sea louse Caligus rogercresseyi is an insidious ectoparasite that affects farmed salmonids in Chile. Effective control of the sea lice requires the use of antiparasitic drugs, which are administered to fish as immersion treatments. These are complex procedures in which a drug solution is poured into the fish cage. Salmon companies have developed their own strategies to perform immersion treatments. These practices have not been fully described nor evaluated in terms of treatment success. The objective of this study was to identify and quantify the effect of different practices on treatment success, through an expert elicitation process. This process consisted in the design of a questionnaire, its application to experts through personal interviews and a group discussion. We organized the relevant factors using a causal diagram (Fig. 1) and the expressed associations as likelihood ratios (LRs). Experts indicated that the most important factors impacting treatment success were: 1) treatment duration, 2) drug concertation in water, 3) preparation of the drug solution, and 4) distribution of the drug solution. This study constitutes the first effort made in Chile to identify the best practices for performing immersion treatments across the salmon industry.