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New Zealand Mudsnail (Potamopyrgus antipodarum)

New Zealand mudsnails (Potamopyrgus antipodarum) are tiny invasive snails that threaten the food webs of trout streams and other waters. Native to New Zealand, they were first found in Idaho's Snake River in 1987. They quickly spread to other Western rivers, sometimes reaching densities over 500,000 per square meter. In the Great Lakes, mudsnails were first found in Lake Ontario in the early 1990s. Since then, they have been reported in lakes Superior, Michigan and Erie. In 2012 they were found in Black Earth Creek in southern Wisconsin.

Anglers pose a risk for spreading New Zealand mudsnails because they can be moved on waders and gear. They can close their shells allowing them to survive out of water for days. One snail can reproduce and start a new infestation. Eradicating infestations is nearly impossible. Your help in detecting and reporting new infestations is vital for preventing their spread.

Identify New Zealand Mudsnails

General Characteristics

  • Small, up to 1/5 inch (5 mm) long
  • Difficut to distinguish from native snails; shell more elongated
  • Usually horn-colored, but ranges from light to dark brown

What You Can Do

Follow Minnesota Aquatic Invasive Species Laws:

  • Clean all aquatic plants, animals and mud from watercraft, trailers, docks, lifts, anchors and other recreational equipment before leaving access.
  • Drain water-related equipment (boat, ballast tanks, portable bait containers, motor) and drain bilge, livewell and baitwell by removing drain plugs before leaving water access. Keep drain plugs out while transporting watercraft.
  • Dispose of unwanted bait, worms and fish parts in the trash.

Also Recommended:

  • Scrub soles of footwear with stiff-bristled brush.
  • Spray watercraft and equipment with high-pressure water, or
  • Rinse with very hot water, or
  • Dry for at least 5 days.

Report New Sightings — note exact location; place specimens in a sealed plastic bag or store in rubbing (isopropyl) alcohol; and call a Minnesota DNR Invasive Species Specialist (see www.mndnr.gov/invasives/contacts.html), 1-888-MINNDNR or (651) 259-5100; or the Minnesota Sea Grant Program in Duluth, (218) 726-8712.

Know the Rules!

Specimens are needed to confirm sightings, but some jurisdictions prohibit possession and transport of invasive aquatic plants and animals. Contact your local natural resource management agency for instructions. Unauthorized introduction of plants, fish, or invertebrates into the wild is illegal. Protect your property and our waters.

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This page last modified on May 04, 2016     © 1996 – 2019 Regents of the University of Minnesota     The University of Minnesota is an equal opportunity educator and employer.
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