Peter Sorensen and Dan Zielinski demonstrated their project Monday in Genoa, the St. Paul Pioneer Press reported. They said the five-speaker system, which has been operating for about a week, is believed to be the largest underwater speaker system in the world.
The speakers produce a sound that carp hate, which Sorensen said his team determined after conducting experiments in the lab and observations in the field. The noise is equivalent to that of 20 outboard motors.
The $75,000 sound system is activated every time the downstream gates of Lock and Dam No. 8 open. It was funded by state lottery funds and nearly $7,000 in private donations. The project is designed to prevent the carp from entering without bothering native fish.
The invasive fish, commonly known as Asian carp, are thought to be a major threat to native aquatic species throughout the Midwest. State and federal officials, as well as fishermen and scientists, are concerned that the carp could push out walleye, northern pike and bass.
"We're trying to buy as much time as we can while we learn more about these fish and how to deal with them," Sorensen said.
Another option, Zielinski said, is adjusting the speed of water that flows through the dam's gates because carp aren't very strong swimmers.
Mark Clements, who runs a fishing barge near Lock and Dam No. 8, worries that the native fish could be negatively affected by a change in dam operation. But Zielinski assured Clements that any adjustments would be subtle since they are within ranges already set by the Army Corps of Engineers, which operates the dam. Since carp have much more sensitive hearing than native fish, the noise won't bother the native fish either, he said.