"In our most recent survey, we were lucky if we found a few hundred per square meter," says Levri. "In Lake Erie they are not very abundant, but it is unclear what they are doing 100 feet below the surface."
In New Zealand, the mud snails are not a problem because of native trematodes -- flukes -- that infect the snails and controls their population and reproduction. Some people have suggested that those who want to control the snail introduce this trematode to the U.S. to control the snails.
"There are two problems with introducing these trematodes," says Levri. "The first is that any introduction of a nonnative species can cause worse problems than they were expected to cure. The second is that these flukes have a multiple-host life cycle, infecting ducks that are apparently not affected before infecting the snails. This might work in the west where the snails are in shallow water, but no duck is going to dive 100 feet to get snails."
Levri and his team found that in Lake Ontario, the densities of the snails peak between 50 and 82 feet and they were rarely found in water less than 16 feet.
"What we can do is limit their expansion," says Levri. "That means that recreational water users must be very careful moving from one place to another. We advise anglers to freeze waders and fishing gear, or use Formula 409 or something like that to kill the snails."
He notes that signs are beginning to mark areas in New York where the snail is found to warn people to clean their gear.
The Penn State researcher warns that the snai
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