Last modified: Friday, July 27, 2007
New Zealand mudsnails
Potamopyrgus antipodarum
By cleaning their boots, fishing equipment and boats, anglers can do a lot to help protect their favorite fishing water from this threat to Utah's fisheries.
New Zealand mudsnails
Although the New Zealand mudsnail is only three-sixteenths of an inch long, it can develop colonies of more than 300,000 mudsnails per square yard. These colonies compete for food and space needed by trout and other native aquatic organisms.
Mudsnail history
The first discovery of the New Zealand mudsnail in North America was in Idaho's Snake River, in 1987. Since then it has spread to several premier trout streams, including the Yellowstone and Madison rivers.
Mudsnails were found in Utah in 2001, when snails were discovered in the Green River, below Flaming Gorge dam. Since then, they've been found in eight different watersheds in Utah.
A threat to Utah's fisheries
New Zealand mudsnails found in Utah are female and reproduce asexually, which means only one snail is required to establish a new colony. They can reproduce a million young per year and are very effective at colonizing new waters.
In some locations, mudsnails compose more than 95 percent of the biomass. They dominate these areas and because they pass through the digestive system of trout unharmed, they provide little or no nutrition to fish.
Greatly enlarged New Zealand mudsnail
New Zealand mudsnails also have a hard shell, with a protective operculum that closes the shell when the snail encounters adverse conditions. This makes them hardy enough to survive several hours out of water. Their small size also makes it easy for snails to be inadvertently moved from water to water on angler's boots, boats or other gear.
What anglers can do
Mudsnails can easily become lodged in the felt soles and lacings of wading shoes. Anglers also spread mudsnails when they discard the entrails of cleaned fish into the water they've been fishing or when they don't clean their boats thoroughly.
Anglers can avoid carrying mudnsails from water to water by thoroughly cleaning, drying or exposing their gear to freezing temperatures or hot water. Research has shown that the snails are very vulnerable to freezing and high temperatures at low humidities.
Wash your equipment with a solution of 409 cleaner in water that's in excess of 140° F. and allow it to dry for a couple of hours, or freeze your gear and keep it frozen for at least eight hours. These methods should destroy any mudsnails that are on your gear.
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