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A new study states that large numbers of wild salmon are being infected with a virus coming from fish farms.

Biologist Alexandra Morton has studied whether Atlantic salmon raised in open-net pens along the B.C. coast are infected with the piscine reovirus (PRV). Since the farms weren’t keen on her sampling live fish she had to get creative.

“I went shopping and bought 262 farmed salmon from the markets in Vancouver and Victoria and all over B.C.,” she said.

Morton said she found that “95 per cent of farmed Atlantic salmon in the supermarkets are infected by this blood virus, the piscine reovirus.”

WATCH: Fish farm opponents say virus detected

2:16 Fish farm opponents say virus detected Fish farm opponents say virus detected

The results were part of a study that found farmed salmon could pass the virus on to wild salmon that migrate past open-net pens.

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Study co-author Rick Routledge, a professor of statistics at Simon Fraser University, said infection rates were “upwards of 40 per cent or so in the heavily infected areas, then in the areas that are more remote from the fish farms it dropped to around five per cent.”

Jeremy Dunn of the B.C. Salmon Farmers Association said “it’s important to know the piscine reovirus or PRV is quite common in salmon, both wild and farmed.”

Routledge agrees, but says “it is much more common in places near where there are high concentrations of fish farms.”

While the Salmon Farmers Association says PRV does not cause illness, federal fisheries’ research finds that it can infect red blood cells and weaken the fish.

Globalnews.ca coverage of fish farms

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“The fish in lower Fraser [River] are so much more infected than the ones in the upper Fraser, which suggests that infected fish are having tremendous difficulty getting up the river,” Morton said. “That means they’re not spawning.”

“With all these upper Fraser sockeye populations now declared at risk of extinction we just have to take this problem seriously,” Routledge said.