A northwoods lake is overpopulated with invasive fish, but a group of scientists think they've installed the solution underwater.
Crystal Lake near Minocqua hosts tens of thousands of visitors each summer, but it also hosts an invasive fish, the Rainbow Smelt. They can out compete native species like Yellow Perch and Walleye. To kill the smelt, scientists installed a rig underwater to raise the lake's temperature.
"We're attempting to target that cold water habitat that the Rainbow Smelt need," said Jordan Read, a University of Wisconsin-Madison doctoral student and organizer of the project. "In order to do that we're mixing the bottom lake waters, which are normally very cold, with the surface waters which are much warmer. The end result is a lake that is too warm for the invasive fish to survive but has normal temperatures for some of the warmer water fish."
Pneumatic pumps fill bladders underwater that float to raise a platform and cold water to the surface. The group is still finalizing the setup and hope it will help keep the smelt from invading larger water systems nearby.