Researchers at the University of Guelph are processing infected fish tissues and developing diagnostic tests to look at a deadly virus suspected in the deaths of thousands of fish in the Great Lakes basin.
It's believed the virus could be spreading from one species to another, even infecting fish farms and hatcheries.
“Right now there are a lot more questions than answers,” said Rich Moccia, professor of aquatic and fishery science at the University of Guelph. “The reality is most fish in Ontario have been fairly free of many viral diseases that are found in other parts of the world, so all this is very new.”
Earlier this week, researchers from Guelph and Cornell University gathered to talk about how the virus might affect fish farmers and others in the Ontario aquaculture industry. Cornell's Aquatic Animal Health Program has been analyzing the infected fish found in the U.S.
So far the viral hemorrhagic septicemia virus exists in about 12 fish species in the Great Lakes, including round gobies, smallmouth bass, freshwater drum, yellow perch, northern pike, muskellunge and yellow walleye. It does not pose any health risk to humans but causes fatal anemia and hemorrhaging in various types of fish species.
This is the first time this strain of the virus has been found in Canada, and it is still not known where it came from, how fast it will spread or how great an impact it will have on the fish in the Great Lakes. It was first detected in just one species, the muskellunge, found in the northeastern United States in 2005.
In May and early June this year, however, 30,000 dead fish washed up on the northern shores of Lake Ontario in the Bay of Quinte. The Ministry of Natural Resources sent several dozen fish to University of Guelph professor John Lumsden, who identified the virus in the dead drum fish.
Officials in New York State are particularly concerned that the infection of the muskellunge, a popular sport fish in the St. Lawrence River, will result in the loss of tourists during the angling season this summer.
Canadian scientists are watching for signs of infection in rainbow trout, the species most commonly farmed for human consumption in Ontario.
“Our concern is pretty high, especially for some of our farms that grow in cages in the open waters of the Great Lakes,” said prof. Moccia. “They come into contact with wild fish that are the initial carriers ... so we may see the virus developing in farms.”
Other fisheries based on land and not connected with the Great Lakes waters should be free of the virus, he added.
It is believed the hot summer weather influences how the virus spreads – warm water may allow the virus the replicate and lower the natural defences of fish in the lake.
