New Zealand mudsnail Michigan's latest invasive species

Michigan has a new addition to its roster of Great Lakes aquatic invaders -- a tiny snail from Down Under, smaller than a grain of rice, that could spell big trouble.

And it's only known because the right person, was at the right place, at the right time.

Sarah LeSage was on a floating trip with some girlfriends down the Pere Marquette River near Baldwin in Lake County last August, when the group stopped on the banks near Gleason's Landing to relax.

"I thought, 'There are a lot of really small snails here. I wonder what they are? I haven't seen anything like this before,'" LeSage recalled.

Fortunately for a state looking to protect a more than $2 billion sport-fishing economy, LeSage is an aquatic biologist and the Aquatic Invasive Species Program Coordinator with the Michigan Department of Environmental Quality. She took some samples, and the snails were later confirmed as the New Zealand mudsnail, the first time the invasive species had been found thriving in Michigan.

The little critter could have a major impact on the Great Lakes regional ecology, with ripple effects up the food chain that could effect sport fish like trout, salmon and walleye that help make the state's tourism economy go.

Only reaching a size of about an eighth-of-an-inch long, the New Zealand native species is now widespread in many western states, and has been found in Wisconsin. It's very hardy and can be easily transported, as it can live out of water in a damp environment for up to a month.

The snails likely arrived on the boots or waders of fishermen who were fishing in rivers out west, said Seth Herbst, the Aquatic Invasive Species Coordinator for the state Department of Natural Resources.

The mudsnails look harmless enough -- maybe even a little cute. But they're a concern, Herbst said. They reach maturity within a year, and after that, can reproduce hundreds of offspring every three or four months. And the snails can reproduce asexually -- they don't need a male and female for reproduction, he said.

"A single female can result in a colony of 40 million snails in one year," he said. "When they get to be that dense, they out-compete some of the native species."

The snails feed on the same types of algae and other macroinvertebrates -- tiny organisms without backbones -- that aquatic insects eat. Those insects are eaten by small fish that are in turn eaten by Michigan's important, larger game fish.

"History has taught us aquatic invasive species can have a major negative effect on other components of the food web that we care about," said Brian Roth, an associate professor in Michigan State University's Department of Fisheries and Wildlife.

Surveys since the August discovery have shown the mudsnail is "a little more widespread than we initially noticed," including upstream of Gleason's Landing, LeSage said. There is no effective treatment to kill the snails, but both LeSage and Herbst said boaters and fishermen can play a key role in stopping its and other invasive's spread through the thorough rinsing and drying of their boats, trailers, boots, waders and other gear after trips on the waterways.

Citizens also can be on the lookout for aquatic invasive species and report them to the DNR and DEQ at the website www.michigan.gov/aquaticinvasives.

"People's awareness in general can help us make these early detections -- and that can make a difference in early response actions to prevent the spread of invasive species," she said. "You don't have to be a technical person to say, 'Something looks out of the ordinary here.'"