Salish Sea Marine Survival Project

67 DISEASE IMPACTS IN PACIFIC SALMON: THE STRATEGIC SALMON HEALTH INITIATIVE QUESTIONS ADDRESSED DATA CONCLUSIONS What pathogens/diseases may be reducing the survival of BC salmon? What is the role of potential exchanges of pathogens between wild/hatchery and cultured salmon? High throughput infectious agent monitoring to quantitate 47 infectious agents in over 31,000 wild, hatchery and cultured salmon assessed from freshwater through the first 9 months of marine life. Including 3,500 samples from net-pen salmon aquaculture. Host physiological profiling at molecular, protein and cellular levels to study disease processes. High throughput sequencing for viral discovery. Acoustic tracking and stress holding studies conducted to assess linkages between pathogens, disease development and fate. Tracking and holding studies in juvenile and adult salmon identified pathogens linked with fate of individual salmon. Environment is a key driver of pathogen exposure; temperature is the most important driver of infection. 15 viruses discovered that had not previously been documented in Pacific Salmon. Piscine orthoreovirus (PRV ) is linked to disease in BC farmed Atlantic and Chinook Salmon, and is infecting wild salmon. Analyses with 8-10 years of data resolved pathogens associated with reduced survival in Sockeye, Chinook and Coho Salmon. Pathogen assays Individual Fish Figure 1. Heatmap showing duplicate detections of 47 pathogens in wild-caught salmon. Image provided by Karia Kaukinen, DFO. OBJECTIVES OF STUDY The main objective of the Strategic Salmon Health Initiative (SSHI) is to determine what pathogens/diseases, if any, may reduce the productivity and performance of BC salmon (hatchery-produced and wild), their evolutionary history and the potential role of pathogen exchange between cultured salmon and other BC Pacific Salmon. The SSHI project specifically addresses the hypothesis that infectious disease reduces early marine survival of salmon in the Salish Sea. The project also addresses the potential that salmon aquaculture interactions may contribute to risk of disease in migrating Pacific Salmon. HOW? Researchers applied novel genomic approaches to study the presence of pathogens and associated 'disease' expression in wild and hatchery-reared Pacific salmon, and open-net pen cultured Atlantic and Chinook Salmon. Prior studies had suggested that health of salmon can be highly predictive of future survival as salmon adapt to new environments. A sampling program established in 2008 facilitated collection of juvenile salmon from freshwater through the first 9 months of marine residence. SSHI researchers were able to assess shifts in pathogen and disease profiles within and between years for over a decade. A new technology using a high throughput system assessed 47 known pathogens (viral, bacterial, fungal and protozoan) in 80 fish at once (Figure 1); in total over 31,000 salmon were profiled. Molecular physiological assessments based on the activity of salmon genes detected disease-related processes associated with infection and survival. Secondary processing of fish showing signs of viral disease enabled discovery of novel (previously uncharacterized) viruses. Histopathology and In-situ hybridization enabled characterization of cellular damage in the host, establishment of infectivity for novel viruses and co-localization of specific agents within damaged tissues. Molecular profiling of gill biopsy samples from acoustically tracked salmon identified pathogen and disease linkages with fate.

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