MADISON, Wis. – While investigating the cause of a die-off of largemouth bass in Wisconsin’s Pine Lake during But they aren’t yet directly connecting Largemouth Bass Reovirus to the kill in the Forest County fishery.
“We can’t say if it is directly responsible for fish mortality yet,” said Tony Goldberg, a professor and epidemiologist at the University of Wisconsin-Madison. “But these kinds of viruses are known pathogens of fish, so we would be prudent to be concerned about it.”
Additionally, large fish kills involving bass or any other single species have not been previously recorded at the 1,673-acre lake, making the virus a suspicious finding at the least.
“While we are concerned about this development, we aren’t advising any new actions,” added David Giehtbrock, fish culture section chief with the Wisconsin Department of Natural Resources. “We would hope people will continue with their due diligence and follow the rules in place that seek to prevent the spread of viruses and other fish health concerns.”
Remembering the concerns and, in some cases, over-reaction related to Largemouth Bass Virus (LMBV) and associated kills a decade ago, B.A.S.S. Conservation Director Gene Gilliland hopes that will not be the case this time.
“It (LMBV) caused a huge outcry among anglers wanting state agencies to do something (close lakes, prohibit tournaments, etc.), but it was collectively decided that there was little anyone could do,” he said.
“No real transmission mode was ever identified, no real preventatives, no cure. It had to run its course and the affected populations built immunities and recovered.”
The previously unknown virus was isolated at the U.S. Fish and Wildlife La Crosse Fish Health Center from dead fish collected during an investigation of the May 2015 kill. Its genome was sequenced at a “virus hunting laboratory” operated by Goldberg. He and his associates searched through genetic databases to see if it was known or something new.
“Largemouth Bass Reovirus is only the second representative of its group of viruses,” said Goldberg. “This family of viruses are emerging pathogens that infect all sorts of animals. They cause kills in marine and freshwater fisheries, including in wild and farmed populations.”
But, he added, more investigation is needed before it can be determined if it is the primary cause of the Pine Lake bass kill.
No evidence suggests that Largemouth Bass Reovirus, like LMBV, poses a threat to human health.
