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Editorial: Mudsnail scourge major concern
By Ed Engle
The Daily Camera (CO)
Published February 24th, 2005

By now, most Boulder County fishermen know that late last year, Bruce Norikane, a local resident and fly fisher, discovered New Zealand mudsnails in Boulder Creek near 61st Street.

Pete Walker, a senior fish pathologist with the Colorado Division of Wildlife, said that at the time Norikane didn't know exactly what he'd found, but he knew it was something new.

There are a lot of biologists around the state who are in awe of what Norikane did and how he pursued an answer to the mudsnails' identity, Walker said.

The discovery of the mudsnail was not good news. The short course on the New Zealand mudsnail goes something like this:

They are anywhere from about the size of a grain of sand to one-eighth inch long. A mudsnail is an especially resilient critter that can survive in water temperatures from 32 to 77 degrees.

Even more important is the fact that they can live out of the water for many days, and they are especially hard to get rid of because they can close their little shells up tight to prevent poisons from entering.

The reason fishery biologists and fishermen fear the mudsnail in the Rockies is that it has no natural enemies in North America. That means it can multiple at an obscene rate. The mudsnails can virtually take over an aquatic ecosystem from the bottom up, which doesn't leave much room for things like the invertebrates that trout eat.

It's true that trout can indeed eat the mudsnail, but it passes through their system unharmed, offering no nutritive value. Oh, and by the way, the mudsnails reproduce asexually, which theoretically means an entire population could be created from a single snail.

The possible end result of all of these nasty facts is that the mudsnail could deplete your favorite trout stream of trout.

Norikane's discovery is the first evidence of the mudsnail in Colorado. In other western waters where the snail has established itself the population densities can be astounding.

There are places in Yellowstone National Park with more than 500,000 mudsnails per square yard. That can't be good.

With all of this in mind, the Colorado Wildlife Commission closed a 21/2-mile stretch of Boulder Creek to fishing, dogs, hunting or anything that might allow the mudsnails to be carried to another stream.

The first thing that comes to mind, of course, is how could all of this be happening again? Wasn't whirling disease enough? Isn't the spread of chronic wasting disease in Colorado's deer and elk herds enough?

It's even more painful when you examine how this has happened. The first record of New Zealand mudsnails being found in the United States was near Mount Shasta in California. No one knows for sure how they got there. They could have been carried on an angler's waders, or come from a local trout hatchery. When they showed up in the Great Lakes, it was believed that they were carried in the ballast of European ships, where the snail had already established itself.

But when they showed up in the Madison and Firehole rivers in Yellowstone, the Henry's Fork of the Snake River, the Green River tailrace below Flaming Gorge Reservoir in Utah, and Boulder Creek, it is almost a certainty that they were carried there on the wading gear of fly fishermen.

If you look at where the organism is found, it seems to have a real tendency to show up in places where high-end fly fishers fish, said Pete Walker.

There it is. Those of us who travel around the country and the world may have had a hand in this latest case of pestilence over the land.

So what can you do about it? I've heard from some sources that if you thoroughly dry out your wading equipment, that will kill the mudsnail. Other sources say take it a step farther and spray them with soapy water and leave them in the hot sun for several hours. Still others say soak the waders and wading shoes in hot water (120 degrees) for several minutes. The optimists say just thoroughly clean the mud off your wading shoes and rinse them in clean water.

Walker says the one surefire way he's found to kill the mudsnail is to wrap your wading shoes and waders in a plastic bag and put them in the freezer overnight. The one way he says may not kill the snails is to soak them in the kind of bleach baths that kill the whirling disease pathogen.

Ultimately, there is one other consideration. It may be time to hang up the felt sole wading shoes. The felts are a perfect medium for the mudsnails and the whirling disease pathogen to be transported no matter how careful you are.

You can make a case that it was harder for the mudsnail to be transported when fishermen used the old time rubber soled boot foot waders, Walker said.

Walker added that he and a number of others at the Division of Wildlife have switched to rubber soled wading boots.

It's something to think about.

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