Largemouth bass virus confirmed at 3 Indiana lakes


Mar 11, 2001
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Largemouth bass virus confirmed at three northeast Indiana lakes

Indiana DNR

Reports of dead largemouth bass at Steuben County's Hamilton and Little Long lakes this summer prompted Indiana DNR biologists to test for largemouth bass virus (LMBV).

Results from Purdue University's Animal Disease Diagnostic Laboratory indicate that the virus is found in both lakes. Last summer, the first case of LMBV in Indiana was identified in Lake George, which straddles the Indiana-Michigan border in Steuben County.

Bass from Chapman Lake in Kosciusko County are currently being tested for the virus.

LMBV first gained attention in 1995 when it was implicated in a fish die off in South Carolina. It is one of more than 100 naturally occurring viruses that affect fish but not warm-blooded animals. Although the virus can be carried by other fish species, it is only fatal to largemouth bass. Scientists do not know exactly how the virus is transmitted or why it sometimes kills bass. Warm water temperatures seem to be the only common variable identified at lakes where LMBV related fish kills have been confirmed. Scientists know of no cure.

"When fish are stressed, they are more likely to succumb to disease," said Neil Ledet, DNR fisheries biologist. "Stress factors can include hot weather, low oxygen levels, poor water quality and frequent handling by anglers."

Most bass infected with LMBV appear completely normal. In cases where the virus has triggered disease, dying fish may be near the surface having difficulty swimming and remaining upright. LMBV attacks the swim bladder, causing bass to lose their equilibrium. Diseased fish might also appear bloated. Larger bass seem to be more susceptible to the disease.

Although biologists do not know if the virus will have extensive or long-lasting effects on bass populations, Ledet does not think it will harm fisheries in the long run. Bass populations on LMBV-infected lakes have not dropped significantly.

Fish with LMBV are safe to handle and eat. The virus does not infect warm-blooded animals, including humans.

Hoosier anglers can help minimize the impact of LMBV virus by doing the following:

- Drain all water from the bilge and live wells and clean boats, trailers, and other equipment thoroughly between fishing trips to prevent transporting LMBV -- as well as other pathogens and organisms -- from one water body to another. The virus can live for several hours in water.

- Do not move fish or fish parts from one body of water to another. And do not release live bait into the water.

- Handle bass as gently a possible.

- Conduct tournaments during cooler weather, so fish caught will not be stressed by hot temperatures and low oxygen levels.

"Although the virus has been confirmed in only three lakes, the virus may be present elsewhere, so it's important to take precautions against the disease wherever you are fishing," said Ledet.

If you see unusual numbers of dead or dying fish, call the DNR's Turn in Poachers/Polluters line at 1-800-TIP-IDNR, or contact a DNR fisheries biologist. For a listing of Indiana fisheries biologists, go to:


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