LMBV Update Report from MN DNR

The Minnesota Bass Federation Nation (MNBF) helped the MN DNR to conduct a sampling survey on several popular MN lakes this past summer to see if fish in these waters tested positive for LMBV.  Samples were also taken during a Bassmasters Weekend Series event on the Whitefish Chain.

Read Press Release Here or Below:

Bass disease discovered in inland Minnesota lakes (2006-12-12)

A fish disease discovered five years ago in the Mississippi River has spread to Minnesota’s inland lakes, the Department of Natural Resources announced today.

Largemouth Bass Virus (LMBV), an iridovirus, a family of virus that only affects fish, amphibians and reptiles, has been found in 20 states since its discovery in 1991. The disease was found in five of nine metro area lakes sampled last summer.

“We need to keep a sharp eye on the presence and impacts of Largemouth Bass Virus,” said Al Stevens, DNR fisheries program consultant. “The virus has been documented to cause high mortality rates of bass caught and released in tournaments conducted in hot weather.”

The DNR is currently considering rules that could ban off-site weigh-ins at bass fishing tournaments during the hottest times of summer.

Found primarily in the southeastern United States, the disease is known to occasionally cause fish kills, generally in relation to stress from high water temperatures and from handling and transportation by anglers. The disease may spread by either transporting fish or water from infected lakes.

“Anglers should always drain their live wells when leaving lakes,” Steven said. “By taking this action, we can slow the spread of diseases like LMBV as well a number of other invasive species such as zebra mussels and Eurasian water milfoil.”

The DNR partnered with the Minnesota Bass Federation to collect samples following bass fishing tournaments at nine metro area lakes known to receive high fishing pressure. The disease was discovered at Green Lake (Chisago County), Prior Lake, Lake Minnetonka, Rush Lake and Forest Lake. Lakes sampled that were negative for LMBV are Clearwater Lake, North/South Center Lake, Whitefish Lake and Green Lake (Kandiyohi County).

So far, the disease has proved fatal only in largemouth bass. LMBV attacks the swim bladder and may cause largemouth bass to appear bloated. The disease also affects their ability to control their buoyancy and maintain their position in the water column.

Infected, normal looking largemouth bass can be affected by all kinds of stressors including high temperatures and lower oxygen levels.

Other members of the sunfish family known to become infected with the virus include spotted bass, Suwanee bass, smallmouth bass, bluegill, redbreast sunfish, white crappie and black crappie.

Fish infected with LMBV are safe to handle and eat. The virus is not known to infect any warm-blooded animals, including humans. The DNR is considering additional monitoring next summer to better determine the current distribution of the disease in Minnesota and assess its spread over time.


Anglers can help prevent the spread of Largemouth Bass Virus and as well as other fish diseases and the spread of exotic species by taking the following steps:

– do not move live fish or fish parts from one body of water to another and do not release live bait into any body of water; a permit is required to transport and stock live fish in Minnesota

– remove any visible plants and animals from boats, trailers, and other boating equipment before leaving any water body

– drain water from the motor, live well, bilge and transom wells at the ramp access before leaving any water body

– properly dispose of unwanted minnows and leeches on shore; never release live bait into a water body, or release aquatic animals from one water body into another

– minimize targeting of largemouth bass from mid-July to mid-August, especially during exceptionally hot weather conditions

– wash/dry boats and other boating equipment that normally get wet to kill exotics/pathogens that were not visible at the boat launch; recent research has determined that LMBV can live for several days in water, confirming the importance of this practice

– report dead or dying adult largemouth bass to the local DNR fisheries office (office locations and telephone numbers are listed in the Fishing Regulations Handbook).

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