ST. PAUL, Minn. (AP) — The Army Corps of Engineers has tweaked how it runs Lock and Dam 8 on the Mississippi River in Genoa, Wisconsin, in hopes of impeding the spread upriver of invasive Asian carp.

The Corps says it has changed the way it operates the spillway gates at the dam to deter adult carp from swimming through. It has also mounted underwater speakers in the lock gates that broadcast low-frequency noises that deter carp but aren't known to affect important native species.

The changes were recommended by a University of Minnesota team led by Peter Sorensen. He said in the Corps' announcement Wednesday that the changes were designed to stop carp while having minimal effects on native fish and angling. He adds that they don't affect barge traffic either and cost nothing.