The invasive New Zealand mudsnail (Potamopyrgus antipodarum) an NR 40 prohibited species in Wisconsin was discovered in samples collected last season during routine water quality and Water Action Volunteer sampling in Mt. Vernon Creek in the Upper Sugar River Watershed. This is the second reported occurrence in the USRW since 2016 in Badger Mill Creek. The population abundance in these locations is uncertain at this time.
New Zealand mudsnails are now known to exist in five Wisconsin streams, four of which are in Dane and Columbia Counties in South Central Wisconsin. The first population verified in the State was in 2005 in the St. Louis River in Douglas County, in the northern part of the State. Since 2012, populations have been documented in Black Earth Creek and Badger Mill Creek in Dane County, and in Rowan Creek in Columbia County.
The impact of New Zealand mudsnails is not fully understood in the Midwest including Wisconsin, though they are suspected to alter habitats and food chains in western states. State resource managers are actively monitoring this species and working with Great Lakes States to assess populations.
It is suspected that New Zealand mudsnails are being transported through the boots and gear of anglers, as each discovery has been in a designated trout stream. With the Early Trout Season underway since the first Saturday in January, LSRWA encourages anglers and all users of any stream or river to fully inspect and clean all gear that comes into contact with the water before leaving the site or entering another water body. Information, signs, and boot brush stations are being installed at key stream access points in the USRW to assist users.
For more information contact Amanda Smith, WDNR Aquatic Invasive Species Regional Coordinator for South Central Wisconsin 608.275.3283.