Invasive Species Surround S. Dakota Waters

By Travis Gulbrandson
travis.gulbrandson@plaintalk.net
Published: Thursday, March 31, 2011 12:03 AM CDT





South Dakota is bordered on all sides by states in which invasive species live that have the potential to wreak havoc on its rivers and lakes.

“The threat isn’t just at the Great Lakes anymore. It’s literally knocking on our door,” said Paul Lepisto, regional conservation coordinator with the Izaak Walton League of America.

Lepisto spoke about the danger these species pose and the ways outdoors enthusiasts can prevent their spread Wednesday at the fourth annual Missouri River Futures Conservation Workshop at the Clay County 4-H Center in Vermillion.

There are four species with which experts are concerned in terms of the Missouri River, Lepisto said. They are the Asian carp and the silver carp, and two invertebrates, the zebra mussel and the Asian clam.

The Asian carp already is present near Lewis & Clark Lake. The presence is not great, although the carp has been sampled in several different locations.

“At this point, we do not have the Asian carp species or the zebra mussel present in the Missouri River above Gavins Point Dam, so the dam is the barrier right now to prevent these invasive species from spreading further up the Missouri River,” Lepisto said.

While the silver carp is not yet known to be in the Missouri River, it has been found in the James and the Big Sioux rivers.

Silver carp are known as the “jumping fish” for good reason, Lepisto said.

“They’ll come out of the water when there’s a disturbance — a boat going by or a jet ski, a water skier,” he said. “When a school of them gets excited, they’ll start leaping up in the air, four or five feet out of the water. Some of these fish weigh 40 or 50 pounds, so ... they can fly into a boat, strike and injure people who are in the boat. It’s an extremely dangerous thing to have happen.”

The silver carp is such a problem in the Illinois River that there is a service that offers tourists a chance to dispose of the fish through bow- hunting.

“I’ve seen footage of this,” Lepisto said. “Carp are jumping out of the water and people are trying to shoot them with arrows. Shotguns would be more effective, I think, but I don’t think the people that live on the shore or on the water would enjoy shotguns going off.”

Another invasive species, the zebra mussel — named for its distinctive striped pattern — was discovered in Nebraska for the first time this past December. The mussels often attach themselves to hard surfaces on the shoreline of a body of water.

“They’re quite small — less than a quarter in size,” Lepisto said. “Most of the adults are about the size of a dime.”

A group of Boy Scouts discovered one of the mussels on a discarded beer can when they were collecting aluminum at Lake Zorinsky in Omaha.

“It’s a small lake where they didn’t think they would ever have that problem with an invasive species,” Lepisto said.

The lake is owned by the U.S. Army Corps of Engineers and managed by the City of Omaha, which drew down the shoreline in an effort to dry out the mussels or freeze them so that they’ll die and cease to reproduce.

It’s the reproduction rate of this species that causes such concern among biologists, Lepisto said.

“A female zebra mussel will lay 1 million eggs a year, and the fertilized eggs will quickly hatch,” he said. “Then the juveniles, called veligers, will start moving around in that waterway, whether it be a river or a lake, spreading through other areas. They’re very, very difficult to control once they get in the water.”

The smallest zebra mussels can swim into the live wells of a boat, from which they can transfer themselves to another body of water if the boat is not drained or cleaned, Lepisto said.

“They can exist out of that waterway for days without food, so that’s why it’s so important to drain your equipment when you take it out of any water ... before you launch it somewhere else,” he said.

Transfer by man is how these invasive species are introduced to new ecosystems, which is why it is important for boaters to properly clean and maintain their equipment.

The state of South Dakota is doing what it can to educate residents, both young and old, about the threat posed by these invasive species by hosting educational programs.

This year there also will be an increase in monitoring the species, with a total of six monitors to be stationed in different high traffic areas in the state.

Lepisto said he is often asked whether the spread of these species is inevitable.

“Maybe I’m naïve, but I say no. I think that we can prevent these from coming into the waters that we care about and that we recreate on. To do that, we have to have the education, the awareness of the threat of them, and how to keep them out,” he said.

i did a report in college on the homogeneity of Trans Oceanic Harbor flora and fauna. an interesting topic to do research on