We have discovered at least 12 new viruses infecting salmon. I can't tell you a lot about the impacts of those viruses yet, because they have only just come under study. Viruses do carry the potential to have population-level effects. The fortunate thing here in B.C. is that the only reportable virus we have is IHN, which has been shown to have devastating effects at a population level. That is an endemic virus here on our coast. PRV is also occurring in our farmed and wild salmon. No one has ever actually studied whether they have caused changes in diversity or genetic diversity, so I can't really answer that question.
On April 26th, 2021. See this statement in context.