YOU Can Help Prevent the Spread of the New Zealand Mudsnail
By Marilyn Shy, Kalkaska Conservation District
If you fish, wade, or swim in our local lakes, rivers and streams, there is a small critter that may be hitching a ride on your boat, your gear, or even on you!
Adult New Zealand Mudsnail on a penny for scale.
A small mollusk known as the New Zealand Mudsnail has been found in several local rivers as well as in the Great Lakes. The organism has been collected in the Boardman, Au Sable, and Upper Manistee Rivers, as well as Lakes Michigan and Superior, and in Tippy Dam Pond near the Pine River. It may be present in other lakes and streams as well.
It’s tiny, only about 1/8 of an inch long. A dozen of these snails could fit into an area the size of a penny. But its ability to reproduce and wreak havoc on fish populations is nothing short of dramatic, and can be very damaging to local ecosystems.
A single female can produce up to 70 live young every 3 months, without being fertilized by a male. These populations can radically change aquatic habitats by reaching high densities in a short period of time. The species can outcompete native species that are important food for trout. A study done in 2008 showed that rainbow trout subsisting on these mudsnails actually lost weight, as they have no nutritional value. Over half of these organisms passed through the digestive system of the rainbow trout still alive.
Further complicating things, the mudsnails can physically cover egg sites or egg masses, attracting predators of native fish.
Structurally, dense populations of these creatures have the potential to block water pipes and water meters and could be very destructive to irrigation systems.
So what can be done to stop or slow the spread of this invasive little animal?
Here are a few tips for anyone recreating or collecting research information in our local waters:
1) Clean your clothing and all your gear before leaving a site. Scrub waders, boots and fishing gear with a stiff-bristled brush and rinse with clean water. This is often the simplest and most-effective form of prevention.
2) Inspect your gear before it is packed for transport. Visible traces of sand, mud, gravel or plant fragments are signs that the gear has not been properly cleaned.
Or, if you don’t have time to clean your gear on site, then:
3) Freeze your gear for a minimum of 4 hours.
4) Or, soak your gear in hot water, at least 120 degrees, for 10 minutes, then dry for 48 hours.
5) Lastly, you can soak your gear in a 50 percent solution of Formula 409 for 5 minutes, which has been shown to be very effective in killing the mudsnails. Be sure to rinse your gear thoroughly in tap water before using again. And don’t worry. Trout Unlimited staffers have been using Formula 409 for years and not noticed their waders degrading from the cleaner. But it doesn’t help to just spray it on, you must soak the items to be treated for at least 5 minutes in order to be effective.
You can help protect our local waters by following these easy-to-use precautions. For more information on these animals as well as other invasives, visit: michigan.gov/invasives.