Fish Farms a Viral Hotspot for Infection of B.C.’s Wild Salmon, New Study Finds

Wild salmon swimming past B.C. fish farms are at high risk of picking up a virus that causes weakness and affects their ability to reach spawning grounds according to new groundbreaking research published this week in the scientific journal PLOS One (Public Library of Science One).

The study found the percentage of wild salmon infected with piscine reovirus (PRV) was much higher in wild salmon exposed to a large cluster of salmon farms along the B.C. coast than in those that were not.

“In my view allowing piscine reovirus to flow from salmon farms into the marine environment will be viewed as an environmental crime of the highest order,” independent biologist and study author, Alexandra Morton, told DeSmog Canada.
Morton’s concern that enough isn’t being done to protect wild salmon stocks is in line with concerns from some coastal First Nations, which in October occupied two fish farms on the Central Coast over their opposition to open-pen farms. In early December, environmental group Pacific Wild released footage showing clouds of blood emanating from fish plants on Vancouver Island; subsequent testing revealed that that blood, too, contained the virus and other parasites.

The new study also found infected wild salmon were less likely to make it back to high-elevation spawning grounds.

“This study provides the first evidence that exposure to farmed Atlantic salmon is associated with infection of wild Pacific salmon with PRV, a virus of significant concern to both the aquaculture industry and wild fisheries management and that PRV infection may impair the capacity of wild salmon to complete a challenging spawning migration, with the potential for population-level impacts,” the study concludes.

Alarmingly Low Salmon Stocks in B.C. Stoke Fish Farming Concerns
The findings come at a time of alarmingly low salmon returns in B.C. and, adding weight to the concerns, are recent scientific findings that PRV is linked to heart and skeletal muscular disease (HSMI). Although HSMI has not been found in wild salmon it was found at a fish farm in the Discovery Islands between 2011 and 2013.

HSMI makes the fish lethargic — something that is not necessarily a problem for penned fish, but is usually fatal for wild salmon, which are in danger of being eaten by predators such as eagles, seals or killer whales if they lie around on the surface, independent biologist and study author, Alexandra Morton, told DeSmog Canada.

“And we know the fish don’t even have to get HSMI. PRV lodges itself in the red blood cells and affects the ability to carry oxygen from the gills to the tissues,” Morton said.

If the infection progresses, the salmon’s heart and swimming muscles become damaged leaving the fish very weak.

Salmon farming companies would not give Morton access to their fish, so the team of scientists bought 262 farmed salmon and 35 farmed steelhead from supermarkets. Tests found PRV in 95 per cent of the salmon and 69 per cent of the steelhead.

Farmed salmon tested for study.

Highest Density of Infected Wild Salmon Near Highest Density of Fish Farms
The scientists then looked at wild salmon infection rates and found that the highest percentages of infected fish were in high-density fish farm areas such as the Broughton Archipelago, where 45 per cent of the wild fish were found to have the virus.

Wild fish around the Discovery Islands — where the Cohen Commission concluded that diseases from farmed salmon could have an irrevocable impact on Fraser River sockeye returns — were found to have a 37 per cent infection rate and 40 per cent of returning salmon in the lower Fraser River were infected.
However, as Fraser salmon made it to the upper reaches of the river, the infection rate dropped by about 50 per cent.

“This suggests that salmon infected with PRV are less capable of swimming up through strong rapids in places like Hells Gate and therefore unable to reach their spawning grounds,” said study co-author Rick Routledge, Simon Fraser University professor emeritus.

In contrast, in areas furthest away from salmon farms, such as the Skeena and Nass, the infection rate dropped to five per cent.

This is the first study in the world to compare infection rates in wild fish to infection rates in farmed fish and the difference between the north and south is startling, said Morton, an outspoken opponent of open net pen fish farms.

One oddity found in the study was that in Cultus Lake, where, last year, sockeye were listed as endangered, 76 per cent of the trout were found to be infected.

That will need further study, but the hypothesis is that the trout were infected by salmon that travelled through the Discovery Islands and the virus was then incubated in the lake, Morton said.

“It’s a durable virus, a nasty little thing and it can exist for quite a long time outside the fish. It’s shed in the feces and urine,” Morton said.

A recent, video-gone-viral showing “blood water” being pumped into the ocean near Campbell River from Brown’s Bay Packing Company, a farmed fish processing plant, shocked British Columbians — and effluent samples analyzed by the Atlantic Veterinary College tested positive for PRV.

Morton said her research was completed before the video was taken, but effluent from the processing plant could be contributing to the high PRV rate in the Discovery Islands. The discharges are currently being tested by provincial investigators.

The peer-reviewed study is being strongly criticized by the B.C. Salmon Farmers Association which issued a press release accusing Morton of using weak correlational data to draw strong conclusions.

“This paper is part of a deliberate activist campaign led by Alexandra Morton and can hardly be taken as unbiased research,” said Jeremy Dunn, the association’s executive director.

Source: https://www.desmog.ca/2017/12/14/fish-farms-viral-hotspot-infection-b-c-s-wild-salmon-new-study-finds

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