ST. LOUIS (AP) -- The Chinese mystery snail continues to find its way around Missouri.
The Missouri Department of Conservation says that it has confirmed the sixth infestation of the invasive species in the state. This time they were discovered in the Niangua River, considered one of the state's best fishing streams.
State conservation officials say they're worried about the snail's ecological impact on food and habitat resources.
The snails were first found in Missouri a few years ago in the Blue River watershed near Kansas City.
It's unclear how the snails came to the state, but the invasive species are used in home aquariums. Biologists suspect someone dumped them and they quickly multiplied.
Officials said a person on vacation at the Niangua saw the snails and noticed they were larger than the native snails.
"I was glad to get the report," said Craig Fuller, a fisheries management biologist. "They were Chinese mystery snails. Besides being illegal to possess, they have the potential to multiply out of control and upset the ecological balance in Missouri waters."
Chinese mystery snails can be found on both coasts as well as several states in between. They are a danger in part because they can transmit disease, their shells can clog screens of water intake pipes and because they compete with native snails for habitats.
The snails don't attach themselves to boats so some believe they were dumped here.
Tim Banek, the department's invasive species coordinator, said he is not aware of an effective way to eradicate the Chinese mystery snails, but suggests removing or destroying them whenever possible.
Banek recommended that anglers should be cautious when buying live bait because it could contain adults or larvae of invasive species.
"Instead of dumping bait on the ground or in the water, put it in a trash bag and send it to a landfill," he said. "That's a pretty good guarantee that nonnative species won't escape."
(Copyright 2009 by The Associated Press. All Rights Reserved.)