SLICEnce: Understanding sea lice population sensitivity to SLICE treatment

点击翻译按钮获取中文摘要

Canadian salmon production is the fourth largest farmed salmon industry in the world. Farmed salmon is British Columbia's (BC) largest agri-food export with a total economic output of $1.6 billion annually, approximately 6,500 jobs and represents 60% of total production in Canada. This project represents a collaboration between partners that have been heavily committed to the Canadian aquaculture industry for decades, including an academic institution (UPEI/AVC), a non-for-profit organization (BC CAHS), a pharmaceutical company (MERCK), and salmon producers (Grieg, Cermaq and Mowi). Sea lice, Lepeophtheirus salmonis, is an ectoparasite that commonly infects wild and farmed salmonids. The parasite impacts salmon production by limiting their growth, increasing their susceptibility to secondary infections and continued costs of treatment. The average loss of biomass growth has been estimated between 3.62 and 16.55% (Abolofia et a., 2017), and when combined with costs of treatment, results in an estimated US$436M loss annually in Norway. In Canada, only one anti-parasitic compound is licensed for use in salmon to treat sea lice infection, emamectin benzoate (EMB, SLICE ®), sold by Merck Animal Health. Since 2006, reduced efficacy of EMB has been observed throughout the North Atlantic, with large-scale failures occurring by 2009 (Aean et al., 2015), in all farming regions with the exception of Pacific North America. Recently we were able to identify a specific louse genotype associated with reduced efficacy and treatment failures of EMB (Messmer et al, 2018). This problem has spread and cases of decreasing treatment efficacy from EMB are more common in BC. Currently, mitigation strategies to track the level of susceptibility and tolerance of sea lice populations rely on live lice collections and subsequent bioassay data. However, bioassays require a high number of sea lice and the process is labor-intensive and time-consuming with many logistical challenges. The predicted outcome of this project is to develop a rapid-PCR based diagnostic assay capable of identifying sea lice sub-populations susceptible and tolerant to EMB, which can be used on both coasts of Canada to inform treatment decisions.