Scientists say that that an Ebola-like virus, viral hemorrhagic septicemia (VHS), is killing all species of fish in the Great Lakes. Due to a lack of genetic resistance to VHS, fish populations could ultimately be damaged in the same way that the smallpox virus struck Native Americans and Dutch elm disease decimated elm trees, says Jim Winton, chief of fish health at the U.S. Geological Survey in Seattle.
VHS was unexpectedly found in the Great Lakes in 2005, in addition to the St. Lawrence Seaway, the Niagara River and an inland lake in New York. Last year, VHS caused large kills that affected at least 20 species of fish. Currently, scientists are waiting to see if the disease returns in mid-May when water in the lakes warms to temperatures at which the virus attacks.
VHS thrives in water of 40 to 59 degrees. Most water in the Great Lakes has not reached that temperature yet this year.
“VHS is the most important and dangerous fish virus known worldwide,” Winton says. “Its discovery in our fresh water is disturbing and potentially catastrophic.”
It is important that the virus’s spread be stopped. Currently, the United States and Canada restrict the transporting of fish and live bait and telling boaters to wash their boats when moving them between lakes. And Michigan’s Department of Natural Resources has taken the most dramatic action: closing hatcheries that produce three important sport fish — walleye, northern pike and muskellunge.
“The last thing you want to do is get the virus into the hatcheries and become a vehicle for spreading the virus,” says Gary Whelan, who runs the state’s hatcheries and chairs the multistate Great Lakes Fish Health Committee.
“What’s so disturbing is that it’s killing fish from so many species and with amazingly high mortality levels,” says Paul Bowser, professor of aquatic animal medicine at Cornell University. The virus does not threaten humans, Bowser says. “If you cook the fish, heat will kill the virus,” he says.