Carp-killing virus discovered in Minnesota for first time
After thousands of dead common carp were reported in Lake Elysian (Waseca County) last month, MAISRC researchers went to work collecting and analyzing samples. It was determined that koi herpesvirus (KHV) caused the massive die-off; the first such documented case in wild fish in Minnesota.
“It’s been suspected that KHV is present in Minnesota waters,” said Dr. Nick Phelps, lead researcher on the project. “But this is the first time it’s been confirmed. This disease has moved around the world since the 1990s through the koi trade. It’s likely that this fish kill was caused by the release of a pet koi or goldfish that carried the virus. Although highly contagious to common carp, and their color variant koi, KHV does not affect humans and is not known to be lethal to other fish species.”
The bad news: This outbreak highlights the risk of introducing invasive pathogens to Minnesota waters and the possible consequences. “It isn’t just the plants and animals we need to worry about, it is the also the pathogens they carry,” added Phelps. “There are several invasive pathogens on our doorstep that could kill thousands of important sportfish next time.”
The good news: This outbreak highlights the possibility of harnessing a species-specific pathogen to be used as a biocontrol agent for AIS. To that end, MAISRC researchers have been working to identify potential pathogenic biocontrols for invasive carp, zebra mussels and Eurasian watermilfoil. For example, Australia plans to intentionally release KHV next year to control common carp populations.
“There is a lot of research and risk assessment that needs to be done before we know if KHV is a viable biocontrol candidate to safely use in Minnesota. However, from this outbreak, we have learned that KHV is in Minnesota waters and that the associated die-off was not only lethal to invasive carp, but species-specific,” Phelps added. “We thank the folks living on that lake who reported the mortality event so we could learn from it. If you see more fish kills, native or invasive, please report them to our online database.”