SOURCE: Science

DATE: September 4, 2019

SNIP: Three new viruses—including one from a group of viruses never before shown to infect fish—have been discovered in endangered Chinook and sockeye salmon populations.

While the impact of the viruses on salmon health isn’t yet known, all three are related to viruses that cause serious disease in other species.

“We were surprised to find viruses which had never before been shown to infect fish,” said Gideon Mordecai, researcher at UBC’s department of earth, ocean and atmospheric sciences. “Although there’s no risk to humans, one of the viruses is evolutionarily related to respiratory coronaviruses, and is localized to the gills. That suggests it has a similar infection strategy to its distant relatives that infect mammals.”

UBC and Fisheries and Oceans Canada researchers used DNA sequencing followed by tests specific to each virus to screen more than 6,000 salmon from along the B.C. coast, including wild, hatchery and aquaculture fish.

We found the new viruses widely distributed in dead and dying farmed salmon and in wild salmon,” said UBC virologist Curtis Suttle. “It emphasizes the potential role that viral disease may play in the population dynamics of wild fish stocks, and the threat that these viruses may pose to aquaculture.”

One new virus, detected more commonly in salmon hatcheries, infected more than 15 per cent of all hatchery Chinook tested.

Another new virus was detected in 20 per cent of Chinook from fish farms—but was only found in adult or sub-adult salmon. In general, the new viruses were more commonly found in cultured fish populations than in wild.