Largemouth bass virus found in more northern Michigan lakes

Jan 23, 2019

Largemouth bass virus has been found in two more northern Michigan lakes. Samples from Beaver Lake in Alpena County and Avalon Lake in Montmorency County have tested positive. This follows a recent discovery of the disease in Cedar Lake in Iosco County. Both Beaver Lake and Cedar Lake have now seen fish kills related to LMBV.

Largemouth bass virus was first detected in the northern Lower Peninsula last year. It was the first time the virus had killed fish in the state since 2003, when it was present in southern Michigan lakes.

Gary Whelan, a program manager for the Michigan Department of Natural Resources Fisheries Division, says the disease was likely introduced when somebody moved live fish.

"The angling public should at least be aware of the virus," he says. "We certainly suspect it will create additional mortalities in that area over the next few years."

LMBV killed 10 to 20 percent of bigger adult largemouth bass in some southern Michigan lakes in the early 2000's. Their populations recovered after a couple of years. But, Whelan says, things could be different in northern Michigan lakes. 

"We don't know exactly how this virus is going to act as it moves north, because you're at the northern edge of the distribution range of largemouth bass and smallmouth bass," he says.

He also says climate change could make northern lakes more hospitable to the virus, which thrives in warmer temperatures.

"The virus replicates best above about 75 degrees, 77 degrees Fahrenheit," he says. "So, as we get warmer and warmer climates and as we get hotter and hotter summers, it actually makes these lakes more susceptible to this virus replicating because the temperatures are in its favor."

Warming temperatures also stress fish with the virus.

Largemouth bass virus cannot be treated or eradicated; DNR officials say the best way to stop it from spreading is for anglers to clean their gear. LMBV is not known to infect humans and infected fish are safe to cook and eat.