Marine Epidemiology

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Global fish production is in a transition from fisheries to aquaculture. Some coastal seas are now managed for aquaculture production, where populations of domesticated fish can exchange infectious diseases with wild fish. The intensification of parasite transmission (ranging from viruses to ectoparasitic copepods) between wild and domesticated animals is a primary risk factor or the emergence of infectious diseases. Diseases of farmed fish have emerged concurrently with aquaculture expansion, and have become a challenge also for fisheries and conservation. The proposed research has four interrelated projects:******Project 1 is a meta-analysis of global patterns of disease emergence in fish. Across wild vertebrates, fishes have the highest rates of disease emergence, and most cases involve transmission with domesticated fishes as a primary cause. This implies that disease emergence in wild fish is tied to forms of domestication, but it is not clear the risks in relation to types of aquaculture, characteristics of disease agents, environmental factors, and ecological and evolutionary mechanisms. The research will quantify the level of risk of these factors for disease emergence.******Project 2 involves theoretical modelling of disease interactions between wild and farmed fish, including ecological features of disease transmission, evolutionary changes in virulence and drug resistance, and management factors. We will build and analyze mathematical models to evaluate the relative contributions of these processes to characterize the parameter space within which sustainable fisheries and aquaculture can operate. The results will provide a new framework for understanding the emergence of infectious diseases in coastal seas that can be applied to multiple situations.******Project 3 involves fieldwork that will evaluate the infection risks to Canada's most valuable populations of wild salmon along migration routes through the Canada's most productive salmon farming areas. The fieldwork will analyze the infectious microbial communities in seawater at locations along wild juvenile salmon migration routes using a multi-stage filtration process and quantitative molecular analysis (qPCR) to quantify the distribution of 30 different species of parasites (viruses to copepods) that can infect wild juvenile salmon. ******Project 4 will conduct controlled experiments using drug treated and control groups of juvenile fish raised in a hatchery to assess the extent to which protecting wild juvenile salmon from bacterial and crustacean parasites can improve returns of adult salmon. These experiments will provide in-situ data on the role of parasitism by multiple species on the recruitment for a wild fish with an oceanic migration between treatment and recruitment. The data will be of importance to Canadian science and policy on aquaculture, and give a rare insight into natural host-parasite systems overall. **