Salmon virus that is continuously transmitted from fish farms: UBC

A widespread debilitating virus in Atlantic salmon is transmitted to wild Pacific salmon populations via open water pens, according to a new study from the University of British Columbia.

This study, which followed fish ortho-reoviridae (PRV) through genomic sequencing, found that open-net salmon farms were continuously infected with wild juvenile chinook salmon for at least 10 years. Wild species.

Genome sequencing (a process similar to the tracking of SARS-CoV-2 mutants) occurred about 30 years before the introduction of the virus into wild chinook salmon, at the same time that Atlantic salmon eggs were brought to the west coast. I presumed that it was.

It refutes the claim that the virus was introduced during an early attempt to cultivate Atlantic salmon dating back to the late 1800s.

“What’s really important is that when we sampled wild fish near the farm, they were more likely to get infected,” said Gideon, a postdoctoral fellow and viral ecologist at the UBC School of Medicine. Dr. Mordekai said.

Lazy fish are dead fish

PRV, one of the most common viruses found in pen-caught fish in Europe and North America, is known to cause heart disease. However, in Chinook salmon, which did not have time to adapt to the virus at the same time, it causes a disease called jaundice anemia, which causes red blood cells to rupture and damage the kidneys and liver.

PRV poses little risk to human health. In Atlantic-cultured salmon, Mordecai said that almost all pen-held fish became infected by the end of their life cycle, leading to lethargic swimming and loss of appetite.

Although it is difficult to measure how deadly PRV is for wild Pacific salmon species, lesions have been observed in fry and, in extreme cases, can cause jaundice and yellowing. Researchers are worried that the virus may be less likely to affect its ability to feed, avoid predators, or prevent it from swimming upstream and spawning.

As Mordecai said, “You get a lazy fish.”

“The disease caused by this virus is the least deadly. In a way, it makes it more of a problem,” he said, giving him the ability to spread more widely rather than being trapped in a small ring of fateful fish. I pointed out. “It’s a bit like the difference between Ebola and COVID.”

He added: “Salmon is a foundation species. They provide food to people as well as whales and killer whales.”

Evidence initiates a “preventive approach” to aquaculture

Dr. Andrew Bateman of the Pacific Salmon Foundation, co-author of Moldakai, said the findings “support the call for a shift from open-net salmon farming to aquaculture techniques that do not allow the transfer of disease between farmed salmon and wild salmon.” It was.

“The genomic sequencing of this study underscores that PRV is not endemic to BC waters. PRV originated in the Atlantic Ocean and spread worldwide through salmon farming.”

Currently, the Fisheries and Oceans Canada (DFO) does not classify PRV as a pathogen. Mordecai said, “It almost legalizes it through loopholes,” because the Fisheries Act does not allow the industry to bring illness into open water pens.

“My role is to provide evidence,” he said. “This shows that these salmon farms pose a risk.”

The message was recently repeated by veteran DFO scientist Dr. Christie Miller Sanders. Fisheries and Ocean Standing Committee Why two industry veterans couldn’t publish a study showing viral activity in fish farms last month because they were “not happy with the findings and didn’t want to include them in their treatises.”

When asked if DFO’s independence from industry changed in the meantime, Miller Sanders was frank. “Well, I’m supposed to stick to science, but in short, it’s not.”

Mordecai said PRV has been found in all five wild Pacific salmon species, while UBC’s research team has limited research to Chinook.

Further research next year will investigate how deadly the virus is in the wild.

“It’s a kind of big unknown,” Mordecai said.