For the first time, a viral hemorrhagic septicemia virus (VHSV or VHSv) has been identified in fish from Lake Superior, the largest of the five Great Lakes of North America.

The virus was identified by researchers at the Cornell University’s College of Veterinary Medicine and the finding has also been confirmed by the United States Geological Survey’s (USGS) Western Fisheries Research Center in Seattle.

The virus causes viral hemorrhagic septicemia (VHS) in fish and can result in significant losses in wild and captive raised fish populations.

“VHS is one of the most important diseases of finfish,” says James Winton, a VHSV expert working at the Western Fisheries Research Center. “It not only affects the health and well-being of populations of several important native fish species, but it can also impact trade, and, should it spread into the U.S. aquaculture industry, could do substantial damage as happened in Europe and parts of Japan.”

The infection is one of only nine fish diseases that must be reported to the World Organization for Animal Health. Until 2005 it was not known to exist in the Great Lake system but that year it caused several massive die-offs. Since then the virus has been detected in all of the Great Lakes except Lake Superior, and was for instance the culprit when 40,000 freshwater drums died in Lake Ontario over the course of just four days. In addition to the Great Lakes, the virus is also present in the rivers of Niagara and St. Lawrence and in inland lakes in New York, Michigan and Wisconsin.

Previous genetic research carried out by scientists in Canada and the United States show that the VHS virus was probably introduced to the Great Lakes during the last 5-10 years.

Experts now fear that current federal and state restrictions placed upon the movement of fish and fish products won’t be enough to prevent the virus from reaching native fish in the 31 states of the Mississippi River basin.