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The Colorado Division of Wildlife (DOW) is working to confirm if snails found in the South Platte River are the invasive species from New Zealand.

Earlier this week, two anglers brought samples of what they believed to be New Zealand mud snails to the DOW. The samples were collected from the section of river below Elevenmile Reservoir Dam and in Elevenmile Canyon. DOW fish pathologist Pete Walker identified them as New Zealand mud snails. The DOW is working to collect more samples from the river to confirm their presence and measure how far downstream they are established.

The DOW has already implemented a public education program for anglers and other people who use Colorado?s rivers in an effort to slow the spread of this invasive species. New Zealand mud snails were found in a section of Boulder Creek in late 2004, the first known discovery in Colorado. Efforts are underway to finalize a statewide management plan for New Zealand mud snails. DOW biologists will also be working to sample other popular fishing rivers throughout the state to determine where else the snails may be. The DOW is sampling as many streams as possible before the spring run off begins and will continue sampling throughout the summer and fall.

?During a recent New Zealand mud snail workshop held by the DOW on April 20 in Denver, top researchers noted that no significant impacts to fisheries have been documented in any North American river system, even those where the snail has been established for more than a decade,? said Robin Knox, aquatic invasive species coordinator for the DOW.

The mud snail is native to New Zealand and first spread to Europe in the late 1880s and then to the United States in 1987 where it was first discovered in the Snake River in Idaho. The snail, prior to being found in Colorado, had spread to California, Oregon, Washington, Idaho, Montana, Wyoming, Nevada, Utah and Arizona. The snails have been shown to take advantage of new habitats colonizing rapidly. As with most invasive species their numbers tend to peak quickly, but then they drop back and stabilize once they reach equilibrium and find a natural balance.

?I am not surprised that these very hardy snails have been found in another river in Colorado,? said state aquatics manager Eric Hughes. ?I suspect we will make more discoveries of New Zealand mud snails, especially in popular fly fishing sections of rivers throughout the state.?

Mud snails can survive for as much as eight days in dried mud and can be inadvertently moved from place to place on fishing waders, boats, heavy equipment, etc., and it is speculated they may be transferred by waterfowl.

?The DOW will continue to take reasonable steps to slow the spread of this small snail primarily by educating people who might otherwise transport it to new waters,? Hughes said. ?In fact, earlier this year the DOW distributed alert posters to sporting goods stores and license vendors around the state, put up displays at fly fishing and outdoor sports shows, and are working closely with the US Fish and Wildlife Service and organizations like Trout Unlimited to get the word out to all people who use the rivers of the state.?

?Many discoveries of snails in North America have been associated with popular fly fishing streams so all anglers are being encouraged to take strong measures to clean their equipment, especially boots and waders. Submerging in a 50-50 solution of FORMULA 409® cleaner for 5-to-10 minutes will help prevent further spread of this pest,? said Knox. ?The DOW will be evaluating its public education program, and will try to boost public awareness not only for New Zealand mud snails, but also for other invasive species.?

For more information about New Zealand mud snails and ways to prohibit their spread visit:

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2,952 Posts
Yeah, it'd be best if those don't spread. So far they haven't had any detrimental effects on an environment but you never know what can happen.
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