DOW invasive species sampling technicians discovered the mudsnails while conducting shoreline surveys at South Delaney Butte Lake on July 27, 2010. Subsequent testing performed at the DOW's Aquatic Animal Health Lab in Brush confirmed the finding. This is the fourth location where the invasive freshwater mollusks have been detected in Colorado.

Technicians did not find mudsnails during their initial sampling at North and East Delaney Butte lakes. However, the DOW will now conduct a more intensive sampling and monitoring effort to determine the extent of the infestation at South Delaney and the potential that mudsnails may have spread to other area waters.

"The New Zealand mudsnail competes with our native invertebrate species and can destroy forage important to trout and other native fishes," said Elizabeth Brown, DOW's invasive species coordinator. "So far, we haven't seen huge impacts to our fisheries. But New Zealand mudsnails have the potential to seriously disrupt the aquatic communities that are the foundation of the food web. If mudsnails become numerous enough, they can reduce the availability of nutrients to their point where it harms fish populations."

Native to New Zealand, New Zealand mudsnails were first detected in the United States in 1987 in Idaho's Snake River. Since then, the species has spread rapidly throughout the West, infesting waters in Arizona, California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming and British Columbia.

State wildlife officials first discovered New Zealand mudsnails in South Boulder Creek in 2004. Subsequently, the DOW has confirmed infestations in the South Platte River between Eleven Mile and Spinney Mountain reservoirs and in the Green River near the Colorado/Utah border.

Although the potential impact of mudsnails on Colorado fisheries is still unknown, biologists are concerned that like any fast-spreading invader, mudsnails could compromise the health of Colorado's aquatic ecosystems over the long term.

A major reason for DOW's concern is the snail's astounding reproductive capacity. New Zealand mudsnails reproduce asexually and the release of one snail can create a population with a density of between 100,000 to 700,000 snails per square meter. New Zealand mudsnails have no natural predators in outside their native range. Scientists have not yet found a way to contain or eliminate mudsnail infestations.

"Our primary goal at this point is to keep them from spreading, and for that we need anglers and boaters to take common-sense steps to prevent the transport of mudsnails to other locations,” said Brown.

The primary vector for spreading New Zealand mudsnails is human-assisted transport overland, on waders, fishing gear and boats. Unlike zebra and quagga mussels, New Zealand mudsnails cannot attach to hard surfaces. Instead, they "hitchhike" or hide in mud or plant materials embedded on dirty boats and fishing equipment. The mudsnails--only 1/8 inch in length when fully mature--can live out of water for days in mud or other moist environments.

To prevent the spread of mudsnails and other aquatic nuisance species, anglers and boaters should follow the CLEAN, DRAIN and DRY protocol, thoroughly cleaning waders, boats and other equipment after every use.

The DOW also encourages fisherman to avoid using felt-soled wading boots when fishing in New Zealand mudsnail-infested waters. Felt's propensity to collect and hold water and mud greatly increases the chance of spreading New Zealand mudsnails and other aquatic nuisance species. However, fisherman using rubber-soled wading boots should also inspect soles thoroughly to ensure that mud or plant materials are not lodged in boot treads. Waders should be thoroughly cleaned and disinfected between each use.

Public education and participation are the best weapons in the containment of all invasive species, and the DOW will expand its angler education program, implemented at all three Delany Butte Lakes, to increase awareness of this important issue.

For more information about New Zealand mudsnails and how to prevent their spread, please visit the following link: http://wildlife.state.co.us/WildlifeSpecies/Profiles/InvasiveSpecies/NewZealandMudsnail.htm

Wader Decontamination/Cleaning Procedures: Anglers who use waders in New Zealand mudsnail-infested waters should scrub the bottom of waders with a wire brush and remove all mud, plants and organic materials in between each and every use. Anglers should then perform ONE of the following disinfection recommendations before going into the next body of water:

OPTION 1 Submerge waders and gear in a large tub filled with 50% Formula 409 and water for at least 10 minutes, scrubbing debris and visually inspecting waders and gear for snails before rinsing. Rinse water must be from a New Zealand mudsnail-free source (to avoid re-infection) and the chemical bath must be properly disposed of away from the water body.

OPTION 2 Spray or soak waders and gear with water greater than 140 degrees Fahrenheit for at least 10 minutes.

OPTION 3 Let waders and equipment completely dry for a minimum of 10 days in between each use (remember that mudsnails can survive several days out of water).

OPTION 4 Place waders and boots in a freezer overnight between each use.

News Source: Colorado DOW - Aug. 08, 2010