Highly Invasive Snails from New Zealand Found in Baltimore County

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Photo by Michal Maňas, via Wikimedia Commons

Good news! Maryland’s got a new snail. The bad news: it’s highly invasive and could throw off entire aquatic ecosystems around the state.

Biologists and a species expert this month confirmed the presence of the exotic-sounding New Zealand mudsnail in the Gunpowder River in northern Baltimore County, just south of the Prettyboy Reservoir and close to Bush Cabin Run. They were first notified of the tiny snails – between 4 and 6 millimeters long, usually – in early September.

The mudsnail is the first-ever confirmed non-native, freshwater mollusk species in Maryland waters, according to the DNR. Here’s another photo for scale:

Photo via U.S. Geological Survey

Unfortunately, ecosystems in other parts of the country have suffered from the presence of this snail because of its ability to rapidly and asexually reproduce. Female snails can produce “well over 100 clones in a single year,” according to a state release, and the species can thrive in habitats ranging from brackish water and large lakes to tiny streams. It can also survive out of water for weeks at a time, according to a fact sheet from the U.S. Fish and Wildlife Service.

Even worse, the snails don’t offer any nutritional value to fish, so there’s really no benefit to them joining an aqueous community. All in all, they’re pretty parasitic, feeding on organic matter like algae, bark and leaves while giving little back to their neighbors.

The New Zealand mudsnail was first discovered in Idaho’s Snake River in 1987. They’ve since proliferated to western and Great Lakes states and Canadian provinces, and now Maryland.

They’re pretty fast (for snails), being able to travel up to 10 feet per hour, according to the FWS, though they can really get around by affixing themselves to boats, fishing equipment and the like.

Since little can be done to get rid of the fast-spawning molliusks, state officials are asking boaters, anglers and hikers who’ve spent time near the Gunpowder River to check their equipment, fishing gear and boots, and decontaminate them if necessary to prevent any snail sprawl. Boaters should make sure to drain their vessels at the river to keep from bringing them home.

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Ethan McLeod

Senior Editor at Baltimore Fishbowl
Ethan has been editing and reporting for Baltimore Fishbowl since fall of 2016. His previous stops include Fox 45, CQ Researcher and Connection Newspapers in Northern Virginia. His freelance writing has been featured in Baltimore City Paper, Leafly, DCist and BmoreArt, among other outlets. He enjoys basketball, humid Mid-Atlantic summers and story tips.
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