Carp die-off

Dead carp litter the beach Wednesday at Olin Park.  

Wildlife officials are blaming the koi herpesvirus for recently killing off numerous carp in area lakes and streams.

Dead and rotting carp, and the associated stench, have been rife in recent weeks in local lake waters, and several bloated and decaying fish have turned up on the Yahara River and Starkweather Creek.

"The public is not at risk from the koi herpesvirus, and sport fish and forage fish such as shiners have not been harmed," said state Department of Natural Resources fisheries biologist Dan Oele in a press release.

Oele said the DNR is urging property owners to remove dead fish that accumulate on their properties, which can be thrown in a Dumpster, composted or buried. 

The virus is not harmful to humans, but Oele said the decaying fish could be hosting harmful bacteria and urged people to use protective clothing and gloves if removing dead carp.   

The findings differentiate the recent carp deaths from fish die-offs earlier this summer, which were attributed to oxygen depletion caused by decaying algae.

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Koi herpes virus, or KHV, first appeared in area lakes and rivers in 2014 when it was blamed on extensive fish die-offs in Lake Koshkonong, the Rock River and its tributaries.

The virus is highly contagious among common carp and ornamental koi. Mortality rates are high for infected fish, with death often occurring from 24 to 48 hours after the appearance of symptoms, which include discolored or bleeding gills, sunken eyes and blisters. Outbreaks are greatest when water temperatures are between 71 degrees and 79 degrees, according to the DNR.

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Steven Elbow joined The Capital Times in 1999 and has covered law enforcement in addition to city, county and state government. He has also worked for the Portage Daily Register and has written for the Isthmus weekly newspaper in Madison.