NW Fishletter #295, October 21, 2011
[1] Questions Over "Deadly" Virus In Two B.C. Sockeye Smolts
A story about researchers detecting a virus in two wild BC sockeye smolts similar to the bug that had decimated stocks at some European, eastern Canadian and Chilean salmon farms went viral itself earlier this week after the finding was announced at a press conference in Vancouver B.C. on Oct. 18.
Wild fish advocates raised the specter of a wholesale crash in natural stocks on the West Coast and called for shutting down all of B.C.'s farmed salmon industry, even though there was no hard evidence that the virus, called ISA [Infectious Salmon Anemia], came from net pens on the east side of Vancouver Island.
But two days later, the Canadian scientist who had tentatively identified the ISA virus in two samples of 48 samples of juvenile sockeye that were collected in Rivers Inlet, 100 km north of the net pens, said the whole thing was overblown.
As the story spread across the Internet, there was scarce mention that research earlier in the decade had found that wild salmonids didn't seem to suffer from ISA at all, even when injected with it.
It all began with an Oct. 17 press conference at Simon Fraser University, where Rick Routledge, a professor of statistics, announced the findings. Routledge, who is studying the decline of Rivers Inlet sockeye stocks, said in a statement that was released by the university that "ISA is a deadly, exotic disease which could have devastating impacts on wild salmon and the many species that depend on them throughout much of British Columbia and beyond."
The statement said the virus was identified as a European strain, similar to the one that caused two billion dollars in losses to the Chilean aquaculture industry a few years ago. It was thought that the virus made its way from Europe in fish eggs shipped to the farms in South America from Norway.
Routledge and biologist Alexandra Morton, a long-time foe of B.C.'s aquaculture industry, agreed that the only "plausible source" was the Atlantic salmon farms off Vancouver Island.
However, representatives of the BC farmed salmon industry said that they have been testing for the virus for years, and haven't seen a single sign of it in over 4,700 samples. But Morton argued that testing was not adequate and recent data released by the industry showed that many fish tested had symptoms that were similar to those from ISA.
The farmers issued their own statement in response. "These unconfirmed findings certainly are unexpected, unusual and warrant further investigation," said Clare Backman, sustainability director for Marine Harvest Canada.
The farmed salmon group said it was reviewing "the validity of these publicized, but as yet unconfirmed results," and noted that wild salmon weren't susceptible to ISA like the farmed Atlantic salmon. They said they were still concerned about what the discovery meant, and how the disease may have been introduced.
A few days later, Dr. Fred Kibenge, a professor of virology at Atlantic Veterinary College. Prince Edward Island, who identified the virus, told a reporter from The Seattle Weekly that his findings have been blown out of proportion. He said "people are calling me from all over the world -- newspapers, TV, it's ridiculous." Kibenge told reporter Keegan Hamilton that his findings were nothing to change the industry. "It's very unfortunate that people are spinning it this way. It's really dangerous when you put it that way."
But there still may be some question as to whether the strain of ISA found in the Rivers Inlet sockeye smolts has been properly identified.
Dr. David Groman, Section Head of Aquatic Diagnostic Services at the same veterinary college, told fis.com, a fishing industry online news source, that the findings touted by the Simon Fraser researchers were based on real-time PCR [Polymerase Chain Reaction] testing, "with no complete sequencing of the PCR products to do any strain typing of the virus," he said. In plain English, Groman was saying that no virus had been isolated.
Dr. Groman told NW Fishletter by e-mail that the sample was not large enough to completely identify the virus. He said "a shorter segment of the genome was typed and it placed positive in the European classification (this classification contains a large number of variant strains, some are pathogenic and some are not)."
He said the ISA virus is basically divided into European strains and North American strains, as are found in New Brunswick. "Due to the lack of material, the exact European strain of the virus could not be determined immediately, but the results basically indicated that this positive would eventually fall out in the European classification and not the North American one."
"So in short," said Dr. Groman, "so far we have a molecular sequence identified in two samples. NO VIRUS ISOLATED, NO CLINICAL FISH DISEASE CASE, and most importantly, NO DEAD FISH."
The lab results will have to be confirmed before any conclusions can be drawn from the initial B.C. sockeye findings. "Regarding false positives," said Dr. Groman, "all diagnostic laboratories (human and animal alike) have to worry about both false positive and false negative results from automated tests. If you run 1,000 tests you always have some of both results. That is why CFIA [Canadian Food Inspection Agency] and OIE [World Organization for Animal Health] always need confirmation using different tests and different labs on the same samples. So, we will see if these results pan out as good positives or not. Only time will tell."
But other wild fish advocates soon issued statements of their own, calling for a halt to the farming of Atlantic salmon in B.C. The Wild Fish Conservancy said it should stay shut down until more independent testing of wild, hatchery, and farmed fish can gage the size of the threat.
They recommended that Dr. James Winton of the USGS, who heads a fish health group at the agency's Western Fisheries Research Center in Seattle, be given oversight of this process. They also called for the establishment of an independent scientific advisory panel, with emergency funding from both the U.S. and Canadian governments.
Winton told the New York Times it is a "disease emergency" and said research should start now to determine how far the virus has spread.
On Oct. 20, the B.C. government released information regarding the controversy, prepared by Paul Kitching, the B.C. provincial veterinarian and Gary Marty, the B.C. provincial fish pathologist. They noted the two samples that tested positive were from fish that showed no clinical signs of disease. "Therefore these are positive PCR test results only; they do not confirm that the fish had ISA."
They said the CFIA will probably not report theses initial results to the OIE until at least a virus culture or evidence of disease confirms it, and the follow-up could take six weeks or more.
They also took issue with Alexandra Morton's claim that the Cohen Commission had heard that more than 1,000 cases of ISA-like lesions have been reported at BC salmon farms since 2006.
They said every one of those lesions had been tested for ISA virus "using a highly sensitive and specific PCR test," and all fish tested negative. From 2003 to 2010, 4,726 dead farm salmon were tested for the virus and tested negative for the virus.
The B.C. scientists pointed to a peer-reviewed study that found wild Pacific salmon were at low risk if ISA showed up on the West Coast. One of the study's authors was USGS scientist Winton. And they noted in 2008, when Chilean fish farms suffered an outbreak of ISA, coho salmon reared near infected Atlantic salmon, some in adjacent pens, showed no sign of ISA after three years of testing. "This provides strong evidence that coho salmon are highly resistant to ISAV, and a reasonable hypothesis is that sockeye salmon are similarly resistant."
Washington senator Maria Cantwell (D), Lisa Murkowski (R-AK) and Mark Begich (D-AK) have introduced a bipartisan amendment that calls for an investigation of the virus. In an Oct. 20 statement, Cantwell said, "We need to act now to protect the Pacific Northwest's coastal economy and jobs. There's no threat to human health, but infectious salmon anemia could pose a serious threat to Pacific Northwest wild salmon and the thousands of Washington state jobs that rely on them. We have to get a coordinated game plan in place to protect our salmon and stop the spread of this deadly virus."
On Oct. 21, The Canadian Food Inspection Agency announced it was collaborating with Fisheries and Oceans Canada, to investigate the reports that ISA had been detected the B.C. sockeye. They said they were working with the Atlantic Veterinary College and further analysis was underway at the National Aquatic Animal Health Laboratory in New Brunswick.
The agency said results should be available within weeks, and if the disease is confirmed, "the CFIA will, in consultation with partners and stakeholders, identify and take appropriate next steps." In Canada, ISA is a "federally reportable disease," said the CFIA statement, which means that all suspected cases must be immediately reported to them. -Bill Rudolph
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Topic: Lethal virus from European salmon found in wild BC salmon (Read 291008 times)