Kodiak Daily Mirror - Alaska salmon experts wary of salmon virus reports
Alaska salmon experts wary of salmon virus reports
by Wes Hanna / whanna@kodiakdailymirror.com
Nov 08, 2011 | 80 views | 0 0 comments | 4 4 recommendations | email to a friend | print
KODIAK — The announcement last month that a potentially lethal virus may have spread to Pacific populations of sockeye salmon in British Colombia seemed to confirm the direst predictions of fish farm detractors.

But further testing has been unable to confirm some of the initial reports, causing officials to reduce their cries of alarm.

The fast-spreading infectious salmon anemia (ISA) virus is responsible for causing the collapse of Atlantic salmon farming in Chile and elsewhere.

“Loosing a virus as lethal and contagious as ISA into the North Pacific is a cataclysmic biological threat to life,” biologist Alexandra Morton of Simon Fraser University said in a release in mid-October. She is part of the team that released the initial findings of the virus in two sockeye smolt.

Morton’s research partner, fish population statistician Rick Routledge, indicated that for the more virulent European strain of the virus to have occurred on the coast of British Colombia, the only plausible source is fish farms.

Developments this past week have not clarified whether the virus is truly present in wild fish stock populations. No clear answers will be forthcoming until further scientific testing is completed.

In one new wrinkle, further tests came back positive for the virus sequences in other wild species, including coho, chum and chinook salmon gathered by Morton along the Fraser River in British Colombia.

The presence of the virus sequence does not prove the virus is present in the salmon. To fully isolate the virus will take another six weeks.

In another update, the original sockeye smolt that tested positive for the anemia virus were sent for verification to Norway, where one sample tested positive for the virus but rerunning the test could not reproduce the result.

Amid the controversy, Alaska state fish pathologist Ted Meyers said he is waiting to hear if the findings of the virus are valid or not. The tests performed so far are prone to false positive results, he said.

False positives could come from contamination of the genetics, the presence of compounds that interfere with the test, or from degradation of the sample, Meyers said.

“Folks have been concerned,” Meyers said, blaming initial media reports for being inflammatory.

“Consequently, my phone’s been ringing a bit,” he said.

Meyers cautioned the public to bear in mind that there hasn’t been a positive test of ISA in farmed Atlantic salmon from British Columbia after 5,000 tests over an eight-year period.

He also said that Pacific salmon are resistant to the virus.

“We don’t have Atlantic salmon in Alaska, and that’s a good thing,” Meyers said.

If the initial reports are borne out and the virus has crossed to Pacific salmon, Meyers said the state would add a test for ISA to routine testing of the state’s fish stocks.

Alaska’s U.S. Senate delegation is taking a more active stance. A letter signed by Sens. Lisa Murkowski and Mark Begich to the Senate appropriations committee last week asks for an immediate federal response to the potentially devastating salmon virus.

It would task NOAA with confirming the existence of the virus in British Columbia and coming up with an immediate response plan to deter the spread of the virus.

The local Kodiak Regional Aquaculture Association has the virus on its radar, but operations manager Gary Byrne said he would expect it to be identified as a problem in Southeast Alaska before Kodiak would need to consider steps for dealing with the problem.

Contact Mirror writer Wes Hanna at whanna@kodiakdailymirror.com. What is ISA?

Infectious salmon anemia is a virus related to influenza. It is passed from one fish to another through direct contact or from mucus or waste from infected fish. The aquatic disease may also be spread in indirect ways such as by sea lice or from equipment that has not been disinfected.

The virus attacks cells lining various organs, causing internal bleeding, anemia, and failure of organs including the kidney, liver and spleen. Outwardly the infected fish may show a darkened skin surface, pale gills, bulging eyes and lethargy.

The virus does not spread to people because it is not active at a human’s higher body temperature.

Various strains of the virus exist, some of which don’t cause disease or significant die-offs. Thus far, infectious salmon anemia is known to cause significant mortality only of Atlantic salmon in marine net pens, though it has been shown to be able to infect other species, including herring and rainbow trout, in the laboratory.

— USDA Animal and Plant Health Inspection Service
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