Endangered wild salmon infected by newly discovered viruses

Mordecai, Gideon J; Miller, Kristina M; Di Cicco, Emiliano; Schulze, Angela D; Kaukinen, Karia H; Ming, Tobi J; Li, Shaorong; Tabata, Amy; Teffer, Amy; Patterson, David A; Ferguson, Hugh W; Suttle, Curtis A

It is thought that infectious disease may contribute to salmon declines (Miller et al., 2011) , but little is known about infectious agents, especially viruses, endemic to Pacific salmon. Infectious disease has been identified as a potential factor in poor early marine survival in migratory salmon; an immune response to viruses has been associated with mortality in wild migratory smolts and adults (Miller et al., 2011; Jeffries et al., 2014) , and in unspecified mortalities of salmon in marine net pens in British Columbia (BC) (Miller et al., 2017; Di Cicco et al., 2018) . For instance, immune responses to viruses such as Infectious haematopoietic necrosis virus (IHNV) and potentially undiscovered viruses, have been associated with mortality in wild juvenile salmon (Jeffries et al., 2014) . This is an important observation as mortality of juvenile salmon can be as high as~90% transitioning from fresh water to the marine environment (Clark et al., 2016) . Together, these suggest that there are undiscovered viruses which may contribute to decreased survival of Pacific salmon but a concerted effort to look for viruses that may contribute to mortality has been absent.