Invasive mudsnails discovered in Yuba River west of Lake Tahoe | SierraSun.com

Invasive mudsnails discovered in Yuba River west of Lake Tahoe

Emily Lavin
elavin@theunion.com

A few New Zealand mudsnails attach themselves to a penny, to provide perspective into their size.

NEVADA COUNTY, Calif. — New Zealand mudsnails have taken up residence in the Yuba River — and the invasive species could pose a threat to the river's native fish populations.

The California Department of Fish and Wildlife has detected the presence of the aquatic creatures both at the Sycamore Ranch park and campground in Yuba County, and at locations on the lower Yuba River above and below the Highway 20 bridge crossing in Nevada County, all a couple hours west of Lake Tahoe.

A release from the agency said it's possible the species originated from a population of mudsnails discovered recently in the lower Feather River; the snails have been known to hitch a ride between bodies of water on the gear of unsuspecting boaters or fishermen.

The New Zealand mudsnails, named for their native country, are tiny, measuring 4-6 millimeters. They have elongated, coiling shells that can be gray, light brown or dark brown, and they live on substrates and vegetation in both fresh and brackish water.

The mudsnails have been found in all Western states except New Mexico. In California, the creatures are known to occupy several bodies of water, including the Russian, lower American and Sacramento rivers.

According to a release from the department of fish and wildlife, dense populations of the snails can have a big impact on the aquatic environment they call home by displacing native species; the snails consume mayflies, stoneflies, caddisflies and other aquatic insects that are usually eaten by the river's trout and salmon.

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"It makes a total change to the food chain, which means that native fish won't live where invasive snails are," said Rachel Hutchinson, the river science director for the South Yuba River Citizens League.

That's a big concern for the nonprofit, which focuses on uniting the community to protect and restore the river. Hutchinson said the group will look into ways to control the population of the mudsnails, and has already had conversations with Gold Country Fly Fishers, a fly fishing club active on the Yuba, about steps club members can take to ensure they don't help the species spread.

"We're all responsible for making sure that this snail doesn't make its way into every nook and cranny of the Yuba," Hutchinson said. "The only way to prevent its spread is for individual people to take responsibility."

The department of fish and wildlife is advising boaters, anglers and other visitors to the Yuba or lower Feather rivers to inspect waders, boats, float tubes, trailers or other gear after leaving the water; and, if possible, to freeze gear for at least six hours or completely dry out wet gear.

"It's critical that anyone who uses infested waters for recreational purposes be extremely vigilant about checking for snails," said Colin Purdy, senior environmental scientist at the department of fish and wildlife, in the department's release.

Any visible mudsnails should be removed with a stiff brush, and then gear should be rinsed.

The department also warned against transporting live fish or aquatic plants or animals from one body of water to another.

Biologists at the department of fish and wildlife are checking for mudsnails in high-traffic areas, boat launches, access points and side channels of the Englebright and New Bullards Bar reservoirs and upstream parts of the Yuba River to see if the population has spread.

The department also plans to educate the public about the presence of mudsnails in the Yuba River by hanging signs at parks, campgrounds, marinas, bait shops and boat launches along the river.

Emily Lavin is reporter for The Union newspaper in Grass Valley and Nevada City.