Fish Virus Feeds Fears It Will Spread to Mississippi River

"VHS, in general, is probably the most significant fish disease worldwide, and the Great Lakes strain is even more of a concern, because it seems to affect a wider range of species," said Ken Phillips, a microbiologist at the U.S. Fish and Wildlife Service fish health lab in La Crosse, Wis.

Wisconsin officials fear that the virus could sabotage their decade-long efforts to stabilize the yellow perch population after a serious downturn in the 1990s.

Ohio officials are worried the Little Manistee River steelhead trout from Michigan, on which they depend to stock their hatcheries, could test positive for VHS, meaning they could not be imported.

Last spring, members of the Lake Carriers' Association, which transport iron ore, coal and limestone on the Great Lakes, adopted voluntary measures to try to prevent VHS transmission. These include inspecting the intake screens, which keep fish out of ballast tanks, yearly instead of every five years, and using pumps to discharge ballast, "so any live fish will be ground up into fish goo," in the words of association President Jim Weakley.

The administration's fiscal 2009 budget includes $2.53 million for VHS activities carried out by the Department of Agriculture, and the farm bill authorizes Agriculture's Animal and Plant Health Inspection Service to consider VHS a high priority.

Many state natural resources officials say VHS outbreaks could have serious effects on commercial and sport fishing industries. But Chuck Pistis, state coordinator for the Michigan Sea Grant, thinks fears are overblown.

"The dire predictions made several years ago have not really showed up yet," he said. "It's better to be proactive and plan for it than be sorry, but there's still a lot of difference of opinion on whether the worst-case scenario of massive die-offs will take place or not. I could think of much bigger issues affecting the industry, like gas prices."