Genomic Profiles of Ocean Migrating Salmon Can Predict Fate to Spawning Grounds

Functional genomics can provide a genome-wide profile of the health and condition of an organism.  We applied this technology to identify genes and potential mechanisms associated with the unprecedented high levels of en-route and pre-spawning mortality experienced by sockeye salmon returning to spawn in the Fraser River.  In three independent radio-tracking studies with sampling in the ocean, upon entry into the river and at spawning grounds, we identified the same genomic signature associated with premature mortality in the river.  The escalation of the immune response, specific to fighting intracellular pathogens, and stimulation of genes and biological pathways known to be co-opted by viruses led us to hypothesize that the signature associated with mortality was of viral origin.  This study is the first indication that disease present before salmon enter the river may be impacting spawning success.  We explore this signature in the context of the high variance in returns of sockeye salmon to the Fraser River.