Invasive snails found in two additional Wisconsin streams

New Zealand mudsnails are small and can go undetected.

MADISON – New Zealand mudsnails, an invasive snail, have recently been verified in two new streams in Dane County, and the Wisconsin DNR is asking anglers to help prevent the spread of this organism to other waterbodies.

Brewery Creek is a tributary to Black Earth Creek and is located in Cross Plains. The furthest upstream verified sites were roughly 0.6 miles upstream from the confluence with Black Earth Creek. New Zealand mudsnails were first confirmed in Black Earth Creek in the fall of 2013. Oregon Branch of Badfish Creek is located just east of Oregon. This site is the first confirmed infestation of the mudsnail in the Rock River Watershed.

These findings now make six known inland streams with populations of these invasive snails. All six streams are in either Dane or Columbia counties.

The New Zealand mudsnail is an NR40 prohibited invasive species, meaning that this species has the potential to cause harm to the environment, human health, or the economy. The small snail can outcompete native stream insects that serve as food for fish, possibly depriving some fish of their preferred food. However, it is uncertain what impacts this invasive species will have on Wisconsin streams.

Due to the tiny size, “stickiness” to boots and other surfaces, and their ability to survive out of water for a long time, special precautions need to be taken to prevent transferring the mudsnail to new waters. Therefore, people who wade streams for any reason are strongly encouraged to use a brush to scrub their boots and waders to prevent transporting New Zealand mudsnails. Boot brushes are sometimes available for use at kiosks at popular trout fishing access points. Equipment can also be thoroughly rinsed with tap water after scrubbing but only away from any streams or waterbodies. Freezing gear for at least eight hours will further reduce the risk of transporting New Zealand mudsnails to other streams.

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