‘Novel’ virus not so novel, after presence found in steelhead samples from 1977

A “new” virus found in BC farmed and wild salmon isn’t so new after all.

Piscine Reovirus (PRV) has been around since at least 1977, according to a new peer-reviewed paper soon to be published in the Journal of Fish Diseases, with Dr. Gary Marty as lead author.

The study tested 363 preserved samples of fish from 1974-2008, and 916 fresh-frozen samples from 2013.

None of the fish showed signs of Heart and Skeletal Muscle Inflammation (HSMI), which some research done in Europe suggests may be linked to PRV.

In the past several years, PRV has been found in wild and farmed BC salmon. Last year, activist Alexandra Morton used this to launch a lawsuit against Marine Harvest Canada, alleging that the company put “diseased fish” into the ocean.

She quickly followed up the lawsuit by co-authoring a study on PRV and HSMI which suggests the version of the virus in BC diverged from the Norwegian strain in 2007, implying, of course, that somehow salmon farms in BC introduced the virus from Norway.

The study was unfortunately rather poor. Its biggest weakness is the small sample size.

  1. It relies on only 14 samples of fish taken in BC.
  2. It relies on only 10 samples of Atlantic salmon.
  3. All of the samples were taken in 2012.
  4. All of the conclusions about virus divergence are based on computer modelling.

In this study’s conclusion, it states that “Our work suggests PRV entered both Chile and western Canada recently.”

This year’s Marty study shows last year’s PRV study is wrong.

KeplerIn science, if you make a prediction about how something should work, and that prediction fails, your hypothesis was wrong and you start over.

The predictions made by the study co-authored by Morton are wrong, in light of the new Marty study.

Salmon farms did not introduce PRV to BC; it’s been here for decades and since before the first salmon farm was built, and maybe even longer.

One more tidbit: Marty’s study also showed that archived samples of Alaskan salmon carried PRV, too.

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