Vaccinology and resistance to bacterial infection in lumpfish (Cyclopterus lumpus)

Abstract

Aquaculture is one of the fastest-growing food sectors, contributing approximately 80 million tonnes of aquatic animals with a value of US $232 billion. Salmon is the most commercially important farmed seafood species cultured in Canada. Farmed salmon (e.g., Atlantic salmon, Coho salmon, and Chinook salmon) account for about 90% of the total finfish produced by Canada’s aquaculture industry. Globally, one of the most significant challenges in salmon aquaculture today is sea lice infestations, costing producers up to CAD $785 million in losses and treatments, impacting sustainability. Sea lice (Lepeophtheirus salmonis, Caligus sp.) infestations are challenging to control. Several methods have been investigated to manage sea lice infestation, including chemotherapeutants, mechanical, thermal, and biological delousing techniques. The biological delousing techniques involving cleaner fish have been shown to reduce sea lice levels significantly and eliminate the use of chemotherapeutants. Cleaner fish, such as lumpfish (Cyclopterus lumpus), is one of the successful strategies to biocontrol sea-lice infestation in farmed Atlantic salmon. The successful utilization of this biological control has resulted in an exponential increase in lumpfish commercial production since 2008. Scaled production and maintaining the health of lumpfish in an industrial environment is the key to a successful cleaner fish strategy. Cleaner fish delouse salmon skin by eating the parasite and ingesting other potential pathogens transmitted by sea lice. Bacterial infections such as Vibrio anguillarun and Aeromonas salmonicida have caused the mortality of lumpfish in the North Atlantic. Fish health, including effective vaccine design and vaccination programs, have been identified as a high priority by the Newfoundland Aquaculture Industry Association (NAIA) and the Government of Newfoundland and Labrador (NL). Besides vaccines, selecting lumpfish families resistant to infectious diseases is an ideal measurement to maximize the efficacy of cleaner fish utilization. The general objective of this study is to improve lumpfish health through vaccination and genetic selection. The specific goals were to i) evaluate the safety and protective efficiency of an autogenous vaccine in lumpfish (Cytopterus lumpus) against V. anguillarum under controlled and field conditions (Chapter 2) and ii) determine the Major Histocompatibility Complex II (MHCII) polymorphism conferring resistance to bacterial infection in Cyclopterus lumpus families (Chapter 3).