New Zealand Mudsnail

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 invasive New Zealand mudsnail to new waters.

New Zealand mudsnails, an invasive species of snail, have recently been verified in two new streams in Dane County, prompting the Wisconsin Department of Natural Resources to ask anglers to help prevent the spread of this organism to other water bodies.

New Zealand mudsnails were first confirmed in Black Earth Creek in the fall of 2013, but Brewery Creek, a tributary to Black Earth Creek, now has verified sites roughly 0.6 miles upstream from the confluence with Black Earth Creek. Another confirmed infestation of the mudsnail has been found in the Oregon Branch of Badfish Creek, the first confirmed infestation 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.

All water users play an important role in preventing the spread of the New Zealand mudsnail. Anyone can help prevent the spread of invasive species by following the Stop Aquatic Hitchhikers guidance of: inspecting your equipment, which includes boots, waders, nets, fishing gear, boat livewells, boat hulls and trailers; removing any attached aquatic plants or animals from equipment; draining all water from boats and equipment; and never moving live fish away from a waterbody.

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 water bodies.

Freezing gear for at least eight hours will also further reduce the risk of transporting New Zealand mudsnails to other streams. By using these prevention strategies, water users can help protect our fisheries and stop the spread of invasive species.