Invasive Mudsnails Reach Southern Michigan Streams
The cloning snails, already established in northern rivers since 2015, now appear in a Kent County tributary of the Thornapple River.
Updated on Nov. 2, 2026 in Environmental
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Invasive New Zealand mudsnails have been confirmed in Bear Creek, a tributary of the Thornapple River in Kent County, marking their first detection in southern Michigan. Volunteers with the Coldwater River Watershed Council found the snails, and experts from Oakland University and Trout Unlimited confirmed the identification. This is a documented field finding, not a shipped or settled management response.
Why it matters
The discovery extends the known range of an invasive species already established in several northern Michigan rivers into the southern part of the state. Because the snails reproduce by cloning and face few natural predators in North America, their spread is a concern for stream ecosystems across Michigan.
Field identification by volunteers, confirmed by Oakland University and Trout Unlimited, places the snails in southern Michigan for the first time. Each snail can produce more than 200 offspring per year, and documented densities reach 300,000 per square meter in Western states. The source of the Kent County population and the size of the infestation remain under investigation.
The players
Oakland University
A Michigan public research university whose experts confirmed the mudsnail identification and which is preparing genetic testing to trace the population's source.
Trout Unlimited
A coldwater fisheries conservation organization whose experts helped confirm the mudsnail identification in Bear Creek.
Coldwater River Watershed Council
A Michigan watershed group whose volunteers discovered the mudsnails in Bear Creek and sent photos and samples for confirmation.
Michigan Department of Environment, Great Lakes and Energy
The state agency that received the photos and samples and handles confirmation of invasive aquatic species in Michigan waterways.
The details
New Zealand mudsnails are brownish black and grow to about one-eighth of an inch long. All of the snails in these populations are female, and they reproduce by cloning: their embryos develop completely without fertilization by a male. That allows a single snail to seed a new population, and one snail can produce more than 200 offspring each year.
Timeline
- 2015: New Zealand mudsnails were first found in Michigan.
- November 2, 2026: Mudsnails were found in Bear Creek, Kent County.
The Tech Race
This story sits in the environmental monitoring field rather than a technology race, and the relevant trajectory is the one set by the 2015 Michigan detection and its established northern populations. The genetic testing Oakland University is preparing will be the next data point in tracing how the species reached the southern part of the state.
Anglers, paddlers and landowners along Bear Creek and the Thornapple River may see changes in stream conditions as snail densities rise. Because food for other stream invertebrates can become scarce at high snail densities, the effects could reach the fish and wildlife that depend on those species, though no timeline for such effects has been reported.
The takeaway
Watch for the results of Oakland University's genetic testing, which should reveal where the Kent County population came from. Those findings will show whether the snails spread from the northern established rivers or arrived separately.
What happens next
Oakland University's genetic testing on samples will identify the source of the Kent County population, though no completion date has been announced.
Further reading
For broader context on invasive species threatening Michigan's waterways, see the Environmental section.
Source note: This article includes information reported by WOODTV.
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