Minnesota officials are turning to new ideas in their fight to keep the bighead and other Asian carp out of the Upper Mississippi. The Department of Natural Resources is considering a wall of bubbles and noise to keep the carp from migrating up the river. The bubble and noise barrier could be installed near locks and dams along the river, including one in far southeastern Minnesota. The DNR is rejecting an earlier idea of using an electric fence because it's expensive. The Asian carp can grow to more than 100 pounds, and some species are dangerous to people because they fly out of the water when disturbed. They also affect native species of fish because they eat much of the food in the river. Morning Edition host Cathy Wurzer spoke with Lee Pfannmuller, the DNR's Director of Ecological Service.