Still no definite detection of ISA in British Columbia

Canada: Retesting of samples previously suggesting that the virus was present in West Coast salmon fail to show evidence of virus presence. Even if it was, chances are that it didn’t come from farmed salmon egg imports

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Opinion

Odd Grydeland

The battle over public opinion around the reported findings of genetic material that suggests that the Infectious Salmonid Anemia (ISA) virus is present in Pacific salmon continues. Industry insiders and supporters have found it suspect at best when extreme environmentalists with a long history of “crying wolf” are paraded in front of the TV camera to announce that a positive test for ISA has been found in samples provided by the Simon Fraser University which has given a honourary degree to the most rabid, anti-salmon farming critic in British Columbia- “Dr.” Alexandra Morton. And the alarm bells went off again last week, when supposedly another sample implicating Dr. Morton- this time from a dead Pacific Coho salmon supposedly found in a tributary to the Fraser River- was reported by The New York Times to have the virus, despite the fact that Coho salmon is the species of Pacific salmon generally considered by salmon culturists to be “bullet-proof” against exposure to viruses of any kind. Strong resistance to laboratory exposure to the ISA virus has already been documented in Coho salmon.

The initial claim that ISA virus was detected in Pacific salmon in British Columbia came from samples of Sockeye salmon provided to the Atlantic Veterinary College at the University of Prince Edward Island by staff from the Simon Fraser University in Vancouver. But as today’s announcement by Mainstream Canada describes, the same samples tested at the University of Bergen failed to confirm the presence of the ISA virus in B.C.;

Independent tests at one of the world’s top ISA virus research labs reanalyzed 48 samples of Pacific salmon and did not find conclusive evidence that any of the fish had ISA. This week, Dr. Are Nylund at the University of Bergen (Norway) reanalyzed tests done last month on 48 Pacific salmon by Dr. Fred Kibenge at the University of Prince Edward Island (UPEI). After extensive re-testing, Nylund did not find conclusive evidence that the fish had the Infectious Salmon Anemia (ISA) virus.

Sampling for this virus is extremely sensitive, so Dr. Nylund tested and retested the samples. One of the samples was tested 33 times; in that sample he found one weak positive result and 32 negative results. In a recent interview, of which Mainstream has obtained a copy, Dr. Nylund explained, “The test material we received was of poor quality, and all tests were negative except the one which was weakly positive. This means that I could not confirm the results from Kibenge, since he found two clearly positive findings and concluded that this had European origin.”

Dr. Nylund continued, “This also means that a virus having genetic similarities with ISA or something totally different may be picked up by the test. Therefore we need to sequence/genotype the virus to provide serious comment on the origin.” He said the findings could represent a previously unknown type of Pacific Ocean virus. “Not all ISA-type findings are described, and there are surely many we have not yet discovered,” he said.

Nylund said that it’s possible any newly-discovered virus could have its origins in ancient evolution. “Today there are several examples of pathogens that are related and which have a North Pacific and a North Atlantic type. One example of this is the Paramyxo virus,” he said. “The reason for this is that the salmon and some of its pathogens in the Pacific and Atlantic once had the same origin, but they have developed differently as they have been geographically isolated over a long time.”

Thousands of farmed and wild salmon have been tested for the Infectious Salmon Anemia virus (ISAV), in British Columbia, including more than 1,200 in 2011 alone. All of those tests were negative and they show that to date, there is no ISAV in our fish, farmed or wild. But two weeks ago anti-aquaculture activist Alexandra Morton claimed Pacific salmon collected by Simon Fraser University researchers had been infected with the European ISA virus. She made the claim before the tests were even concluded, spreading fear and concern without any basis in fact. The fish were sent for re-testing to one of the world’s top ISA virus research labs at the University of Bergen in Norway and those results do not support Dr. Kibenge’s findings, nor do they give conclusive findings on the origin of the virus.

Another new lab report published by Ms. Morton indicates that Kibenge tested another batch of samples she submitted, and one of the 20 apparently showed a weak positive result. However, Kibenge cautioned in his report that “the presence of ISA virus sequences in the tissue samples does not imply that the subject fish had ISA or that ISA is present in the area where the subject fish were collected from.”

Nobody in B.C. are saying with certainty that the ISA virus is not here, but there is a growing level of suspicion that positive sampling results announced by environmentalists are suspect at best. If it would turn out that the virus indeed was present in populations of salmon in B.C. or anywhere else in the Pacific Northwest, chances are that it didn’t come here with eggs imported by the salmon farming industry. Contrary to claims made by environmentalists, true vertical transmission of the ISA virus from parents to off-spring has never been demonstrated. Unlike pathogens like the bacteria that causes Bacterial Kidney Disease in salmon (Renibacterium salmoninarum), the ISA virus doesn’t seem to be able to survive inside a fertilized salmon egg. But that doesn’t mean that ISA cannot be transmitted through the shipment of eggs from one facility or country to another, such as the case of ISA in Chile seem to indicate. ISA can be found in the ovarian fluid, and the difference is in the practice of surface-disinfection of the eyed eggs. If this is done properly, there should be no chance of ISA virus being moved from the brood stock facility to hatcheries.

All Atlantic salmon eggs brought in to B.C. by the aquaculture industry should have been properly disinfected prior to shipment from Europe, and also upon arrival in B.C. according to the regulatory regime established for these shipments. Broodstock would also have been sampled prior to the issuance of permits for egg importations.