ODFW in a race to kill invasive snails

ODFW in a race to kill invasive snails
Photo courtesy www.animalpicturesarchive.com.

MEDFORD, Ore. (AP) — Wildlife authorities are waging a battle against a non-native snail found by the thousands in two White City ponds before the snails can wreak havoc among native species throughout the Agate Desert.

Oregon Department of Fish and Wildlife crews have sprayed two Jackson County Sports Park ponds near the rifle range with copper sulfate to kill off the currently isolated and unwanted populations of Chinese mystery snails.

It marks the first time in Oregon — and possibly in the United States — that copper sulfate has been used to eradicate this species of algae-eating snails, said Rick Boatner, the ODFW's invasive species coordinator heading the effort.

The snails can be legally purchased from aquarium stores, but it is illegal to release them into the wild.

Since the treatments earlier this month, crews have skimmed more than 27,000 dead snails from the two ponds, and crews and trained technicians will survey the pond weekly for more dead snails, Boatner said.

"That was way beyond what I was guessing and they keep dying, so we're doing something they don't like," Boatner said.

Copper sulfate is an approved snailicide by the federal Environmental Protection Agency. It has been used to kill apple snails in Florida and is regularly used in Eastern states to kill snails known to carry a parasite that causes swimmer's itch, Boatner said.

The compound has not been used on mystery snails in Oregon and Boatner found no references to copper sulfate applications for Chinese mystery snail populations elsewhere.

"What we're doing is totally experimental," Boatner said.

Based on EPA guidelines, crews applied 13 pounds of copper sulfate to one pond and 44 pounds during two applications at a larger and deeper pond, Boatner said.

Jackson County officials posted signs warning people of the application for the EPA-required 48 hours to allow the chemical to dissipate.

Both ponds are on county land just south of Kershaw Road.

Despite the treatments, a snail trap in one of the ponds has captured live snails that survived, said Martyne Reesman, an aquatic invasive species technician who is working on the project.

"They haven't been 100 percent eradicated, but at least we're having good success," Reesman said.

Reesman and fellow technician Becky Hill spent much of Thursday afternoon at the ponds collecting dead snails, which measure up to 2 1/2 inches wide.

"My fear right now is that they are going to burrow into the substrate to hibernate," Boatner said. "If many survive, it could start the population all over again."

The snails are known to carry parasites and diseases that can harm people. And the snails are just one wading dog or swimming kid away from hitchhiking to some other waterway in the Rogue River Basin.

Cipangopaludina chinensis, as they are known by scientists, are somewhat commonly found in aquariums or outdoor water features because they eat algae. They currently are legal to sell in pet stores, but the Oregon Fish and Wildlife Commission is poised at its December meeting to add them to the list of hundreds of exotics that are illegal to possess or sell here.

Oregonians with mystery snails currently in their aquariums will be allowed to keep them, but they will be banned from selling, trading or transporting them, Boatner said.

Mystery snails contain a trapdoor-like feature called an operculum that allows them to effectively seal themselves off against predators.

They likely found their way into the Sports Park ponds when someone dumped the contents of an aquarium or backyard fish pond, Boatner said.

Technicians have found three large koi fish, the largest weighing 11 pounds, in the ponds as well, Boatner said.

A local angler found the snails last year and delivered samples to ODFW biologists in Central Point, but they were not positively identified until this summer.

Since then, Chinese mystery snail shells have been found in Lost River near Klamath Falls, Crane Prairie Reservoir and Big Butte Pond near Bend, Boatner said.

Future treatments for snails throughout Oregon will be handled on a case-by-case basis, he said.

Information from: Mail Tribune

Copyright 2010 The Associated Press.