Alex,
There is no evidence to date that the piscine reovirus (PRV) causes HSMI. It is misleading to call PRV the “heart and skeletal muscle inflamation virus”. There have been correlative studies which have found that PRV is associated with HSMI (Palacios et al 2010), but that is not proof of causation. Dr. Gary Marty did admit that 75% of farm salmon he tested were positive for PRV, but found no signs of HSMI. In these cases, the tissues were actually examined to see if there was HSMI. When you tested those “gutted” supermarket fish did you actually look at the tissues for HSMI or did you just assume that if they had PRV they must have HSMI based on correlative links? Similarly, were those Cultus Lake cutthroat that were found to be positive for PRV examined for the presence of HSMI? Actually your testing did show something – it showed the presence of PRV in healthy market sized fish is common in farmed Atlantic Salmon, but not the cause of disease in those fish.
The fact is that if 98% of those fish you purchased had a deadly virus they would not have survived to market size. HSMI tends to affect younger fish – not the market size fish you purchased from Superstore and the T&T market. This disease usually occurs 5-9 months after transfer of fish to seawater (Kontrop et al 2004). This timing has been recently described by quantifying PRV from heart samples taken at different times in the Atlantic Salmon’s life cycle – right up to slaughter. Viral loads decreased as fish approached 18 months in sea water. Researchers concluded that sequencing of positive samples did not support the hypothesis that HSMI outbreaks are caused by a particular virulent strain of PRV (Lovoll et al 2012). Additionally, right after the Palacios study, 150 Pink Salmon sampled from the Broughton area were tested for PRV. None of them had suspicious heart lesions – all tested negative for the virus (Saksida et al 2012). Clearly, the literature is not 100% supportive of PRV causing HSMI.
Simply finding PRV does not establish a HSMI diagnosis, Alex. Even researchers that found a correlative link between PRV and HSMI agree with that (Finstad et al 2012). You may disagree with the difference between a virus and a disease, but this is a fundamental concept to this whole issue. There is a difference between a virus and a disease. The two cannot be used interchangeably. Fish farm critics do this repeatedly to prove their point and they are simply incorrect. Just because you find a virus in the host does not necessarily mean that the host is suffering from a disease. Viruses are actually part of a larger equation which can involve environmental conditions, individual fitness, physiological stress, etc. These other factors are actually more important than the presence or absence of any pathogen. In addition, it is usually not just one sign that determines the presence of a disease – it could be more than two that are needed to make that determination. You need to examine the tissues – preferably someone who is fish pathologist. Lastly, the reporting of this PRV viral sequence is fairly recent (2010) and has not been officially described or seen using electron microscopy so there is very little information on the how long it has been here or where it came from. If it were to be discovered in BC first then Norway would be saying it was 99% BC strain. Merely saying that the BC and Norway strains are 99% identical does not tell us where this originated.
This does not mean that we should never look at PRV again or neglect to see if it has some other impact (i.e. fitness) or if it is in other fish species like Sockeye Salmon. The issue for me is that I agree that we need to do more about learning about fish diseases, but I do not agree with “your” approach – nor do I find you to be as transparent as you claim to be. For instance, I am still waiting to see your results from earlier this year when you claimed to found positive results of alphavirus at Lois Lake. Why are you still refusing to let the rest of us know about these results? In addition, I find your Department of Wild Salmon website to be vague and misleading - neglecting to state what “standardized protocols” you are using.
As for the contention “that viruses are pouring out into the biggest wild salmon migration route in the world along the eastern Vancouver Island” you forget to mention that Justice Cohen concluded that there is no evidence that diseases on fish farms are out of control or unusually high. However, that should not mean that we do nothing. I agree that our knowledge of the impacts of diseases on the survival of wild Salmon in BC is poor. Cohen agrees that the risks warrant further investigation and has made recommendations to address them. I agree with these recommendations, but it appears by your latest rhetoric that you are in the process of creating your own version of the Final Report by Justice Cohen – using selected quotes from testimony to back-up your claims. It is clear what Cohen says about our current knowledge of ISA and ISAV here. While I am interested in these new results you have I will wait to hear from other qualified individuals as I feel burned in the past by your annoucements.
Finally, seeing as though Dr. Gary Marty is your favourite target it is only fair to see what he had to say in response to your allegations. Here is a Bionews article that members might find interesting.
https://www.professionalbiology.com/sites/default/files/bionews/BioNews22-1-electronic.pdfReferences:
http://www.int-res.com/abstracts/dao/v99/n1/p7-12/http://www.veterinaryresearch.org/content/43/1/27http://www.ncbi.nlm.nih.gov/pubmed/15189375?dopt=Abstract&holding=f1000,f1000m,isrctnPalacios, G., Lovoll, M., Tengs, T., Hornig, M., Hutchison, S., Hui, J., Kongtorp, R.T., Savji, N., Bussetti, A.V., Solovyov, A., Kristoffersen, A.B., Celone, C., Street, C., Trifonov, V., Hirschberg, D.L., Rabadan, R., Egholm, M., Rimstad, E. & Lipkin, W.I. 2010. Heart and skeletal muscle inflammation of farmed salmon is associated with infection with a novel reovirus. PloS One 5(7), e11487.
Saksida, S.M., G.D. Marty, S. St-Hilaire, S.R.M. Jones, H.A. Manchester, C.L. Diamond, and J. Bidulka. 2012. Parasites and hepatic lesions among pink salmon, Oncorhynchus gorbuscha (Walbaum), during early seawater residence. J. Fish Dis. 35:137-151.
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Topic: Letter To Director General Of OIE (Read 25105 times)