Biologists from the U.S. Fish and Wildlife Service’s Fish Health Center in La Crosse, Wis., have confirmed the presence of an exotic virus, Spring Viremia of Carp Virus, in common carp taken from the Calumet-Sag channel near Chicago, Ill. The virus, common to parts of Europe, Russia, Asia and the Middle East, does not pose a threat to humans who handle or consume infected fish. However, the disease is highly contagious to carp, goldfish, koi and minnows. This is the third confirmed instance of the virus in the United States and the first in Illinois.
The infected carp were among fish collected during the Service’s annual goby roundup and Asian carp corral in Chicago waterways in June. Kidney and spleen samples were taken from 30 carp collected. Samples from one of six, five-fish groups tested positive for the virus. The Service’s diagnosis was later confirmed by the national Veterinary Services Laboratory in Ames, Iowa.
“We’re concerned about the potential spread of this virus and its effect on our native fish species, “ said Robyn Thorson, regional director of the Service’s Midwest Region. “We know that certain fish like northern pike can carry the disease, but we don’t know yet if they can die from the virus. We will be working with our state agency partners and tribes to determine how widespread the virus is in the upper Midwest.”
Two outbreaks of the virus were reported in the United States during the spring of 2002. One occurred at a private koi hatchery in North Carolina and another outbreak in wild common carp from Cedar Lake in northwestern Wisconsin. Biologists from Wisconsin Department of Natural Resources and the Service estimated that the virus killed 10 tons of carp from Cedar Lake. Later investigations indicate that the virus may have spread to the Mississippi River. “Like people,fish develop antibodies when exposed to the virus. Our tests found antibodies for the virus in carp collected from the Apple and St Croix Rivers,” said Rick Nelson, director of the La Crosse Fish Health Center.
Fish are most likely to be infected with the disease in the spring or fall when their immune systems are weakened due to cold water temperatures. The public can assist the Service and states with efforts to monitor and control this disease by reporting any sick and/or dying carp to their nearest resource agency or fish health center. Signs of the virus may include darkening of the skin, bulging eyes (pop-eye), swollen abdomens, pale gills, and redness (hemorrhages) in the gills, skin and eyes. Affected fish may appear lethargic, lie on their sides and congregate where water flow is slow.
The Service and the Illinois Department of Natural Resources are planning to sample additional locations on the Illinois River this fall. Along with common carp, two species of Asian carp - bighead and silver carp - will also be sampled. The numbers of these species have increased dramatically in recent years in the Illinois River.
The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System, which encompasses 542 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 64 fishery resource offices and 81 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.
