Biologists say a newly discovered foreign virus is the latest threat to Lake Erie and is responsible for two large spring fish kills in the lake. The hemorrhagic-septicemia virus does not harm humans, but it did cause large kills of freshwater drum in the lake's western basin and yellow perch in the central basin in May.

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"It was as extensive as anything I've seen," said Jeff Tyson, a fisheries biologist at the Ohio Department of Natural Resources laboratory in Sandusky.

The virus causes anemia and hemorrhaging in gobies, muskellunge, freshwater drum, smallmouth bass, bullhead, yellow perch and crappie. Walleye are less affected.

Scientists at the U.S. Fish and Wildlife Service's disease lab at La Crosse, Wis., identified the virus, which first showed up in Lakes Ontario and St. Clair last year.

The virus, common in Europe and Japan, is the latest in a long line of Great Lakes foreign invaders, from lamprey eels to zebra mussels to gobies.

Frank Reynolds, a commercial fisherman from Reno Beach, west of Toledo, noticed dead freshwater drum in Maumee Bay as early as March. Later, bleeding yellow perch showed up in nets.

"The perch had red marks on them like taking a file to them," Reynolds said. "We didn't know what it was."

The virus has been blamed for a large fish kill in Lake Ontario near Rochester, N.Y., and in the St. Lawrence River this spring.

Nearly all the foreign species have been brought into the Great Lakes in the ballast water of cargo ships, and Tyson said the virus could have been brought into Lake Erie in ballast water.

Hemorrhagic septicemia first appeared in the United States in spawning salmon in the Pacific Northwest in 1988, according to a scientist at Cornell University. In 2005, it was found in muskellunge in Lake St. Clair and in freshwater drum from the Bay of Quinte, Lake Ontario, Canada.

The virus is considered a serious disease of freshwater rainbow trout in Europe, according to Paul Bowser, a Cornell aquatic expert.

The virus reproduces best in water between 40 and 60 degrees.

"We're in the mid-60s now so we're pretty much out of it," Tyson said.

Tyson said biologists are working to learn as much as possible about the disease and limit its spread. Bait fish from Lake Erie are being tested to learn whether they are infected. State wildlife biologists also plan to test fish in the Ohio River basin to see if the virus has escaped.

The future, however, is difficult to gauge.

"The way these things operate, you see it and get geared up to address it and you don't see it again for 10 years," Tyson said.