Piscine orthoreovirus (PRV) – which is associated with kidney and liver damage in Chinook salmon – is continually being transmitted between open-net salmon farms and wild juvenile Chinook salmon in British Columbia waters, according to a new genomics analysis published today in Science Advances.
The collaborative study from the University of British Columbia (UBC) and the Strategic Salmon Health Initiative — a partnership between Fisheries and Oceans Canada (DFO), Genome BC and the Pacific Salmon Foundation — traces the origins of PRV to Atlantic salmon farms in Norway and finds that the virus is now almost ubiquitous in salmon farms in B.C. It also shows that wild Chinook salmon are more likely to be infected with PRV the closer they are to salmon farms, which suggests farms transfer the virus to wild salmon. Genome sequencing of viruses from farms and wild fish further indicates that transmission occurs between farms and wild salmon.
"Both our genomic and epidemiological methods independently came to the same conclusion, that salmon farms act as a source and amplifier of PRV transmission," said Dr. Gideon Mordecai, a viral ecologist and Liber Ero fellow with UBC Science and researcher with UBC Medicine, who led the study. "Because separate lines of independent evidence all point to the same answer, we’re confident in our finding."
Read more at: University of British Columbia
Global transmission map of Piscine orthoreovirus. (Photo Credit: Gideon Mordecai)