Review of infectious agent occurrence in wild salmonids in British Columbia, Canada

Abstract

Wild Pacific salmonids (WPS) are economically and culturally important to the Pacific North region. Most recently, some populations of WPS have been in decline. Of hypothesized factors contributing to the decline, infectious agents have been postulated to increase the risk of mortality in Pacific salmon. We present a literature review of both published journal and unpublished data to describe the distribution of infectious agents reported in wild Pacific salmonid populations in British Columbia (BC), Canada. We targeted 10 infectious agents, considered to potentially cause severe economic losses in Atlantic salmon or be of conservation concern for wild salmon in BC. The findings indicated a low frequency of infectious hematopoietic necrosis virus, piscine orthoreovirus, viral haemorrhagic septicaemia virus, Aeromonas salmonicida, Renibacterium salmoninarum, Piscirickettsia salmonis and other Rickettsia-like organisms, Yersinia ruckeri, Tenacibaculum maritimum and Moritella viscosa. No positive results were reported for infestations with Paramoeba perurans in peer-reviewed papers and the DFO Fish Pathology Program database. This review synthesizes existinginformation, as well as gaps therein, that can support the design and implementation of a long-term surveillance programme of infectious agents in wild salmonids in BC. K E Y W O R D SBritish Columbia, historical review, infectious agents, wild Pacific salmonids

Exposure Time of Wild, Juvenile Sockeye Salmon to Open‐Net‐Pen Atlantic Salmon Farms in British Columbia, Canada

“…About half of these farms may be active in any given year (http://www.dfo-mpo.gc.ca/aquaculture/bc-aquaculture-cb-eng.html). Although many infectious agents are naturally occurring in British Columbia salmonids (Jia et al 2020), Atlantic Salmon farms have been identified as a potential contributor to the decline of Fraser River salmonid stocks through increased transfer of sea lice, bacteria, and viruses (Price et al 2010; Kent 2011; Godwin et al 2017). Short time series, however, have limited the statistical power to detect relationships between salmonid survival and pathogen or parasite variables (Connors 2011; Korman 2011).…”

Effects of Physiological Condition on Aspects of Repeat Spawning in Female Steelhead Reconditioned in Captivity

“…Gill copepod number was assessed as a predictor of survival because of its potential association with overall parasite load and immune system function. However, it is understood that that parasite load results from a complex interaction of factors such as exposure and immune response and that other pathogens are likely present that could influence survival in adult salmonids (Jia et al 2020).…”

“…However, it is understood that that parasite load results from a complex interaction of factors such as exposure and immune response and that other pathogens are likely present that could influence survival in adult salmonids (Jia et al. ).…”

Considerations related to the use of molecular diagnostic tests in veterinary clinical and regulatory practice

“…Further, piscine orthoreovirus appears to be widespread in both diseased and nondiseased farmed and wild salmon, especially in species indigenous to the Pacific Northwest. 11 Given the inability to culture piscine orthoreovirus in fish cell lines, the primary means for identifying the virus involve molecular diagnostic tests. However, because no causal link between the virus and disease or death has been proven, it is not clear how to interpret a positive molecular diagnostic test result, especially for salmon that appear to be healthy, or how to interpret a negative molecular diagnostic test result in salmon with heart and skeletal muscle inflammation or erythrocytic inclusion body syndrome.…”