Interactions between migration, marine survival, and disease susceptibility in Atlantic salmon_x000d_ _x000d_ _x000d_

Healthy, sustainable Atlantic salmon (Salmo salar) stocks are important economically, ecologically, and culturally to Canada. However, many populations have been severely decreasing since the 1980s, leading to an endangered listing for many populations by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Currently, the greatest impacts to their survival have been linked to juvenile survival upon entry into the marine environment. In this Strategic Partnership Grant proposal, we will use acoustic telemetry and cutting edge genomic techniques to address several strategic issues. Firstly, with our partners at Fisheries and Oceans Canada (DFO) and at the Atlantic Salmon Federation (ASF), we will examine the role of naturally occurring pathogens in mediating the migration behaviour and mortality of juvenile salmon in populations throughout the Maritimes, Quebec, and Newfoundland & Labrador. Secondly, we will examine the interactions of wild salmon with aquaculture net-pens throughout the region by quantifying residency patterns, migration pathways, and mortality near net-pens. In parallel, we will characterize pathogen profiles in water samples collected near net-pens, and by opportunistically sampling net-pen escapees, which are frequently caught in a fish-ladder on a river in New Brunswick, we will compare disease profiles of aquaculture and wild salmon in the same river. Thirdly, we will examine the effects of hatchery rearing on the behaviour and survival of juveniles salmon. Hatchery rearing is commonly used for salmon supplementation, and by comparing hatchery and wild fish in the same river, we will explore whether hatchery fish have different susceptibilities to pathogens and altered migration behaviour. Ultimately, we will use the data that we collect from these studies to develop models that examine the degree to which mortality can be explained by aquaculture and/or hatchery operations versus natural environmental variation, and whether these are actually preventing the recovery of Atlantic salmon populations. These issues are of paramount importance to DFO and ASF, given that the Species at Risk Act stipulates that recovery strategies must address the threats identified by COSEWIC.