A new study by the Army Corp of Engineers shows electrical barriers in Illinois’ rivers may need to be stronger to stop the migration of the invasive Asian carp. The report found possible scenarios where Asian carp could get past the electrical barriers.

Charles Wooley is with the U.S. Fish and Wildlife Service. He said Asian carp are reproducing about 116 miles south of the Army Corp’s electrical barrier near Chillcothe, Illinois.

“We’re increasing our monitoring with additional techniques that focus more on smaller-sized Asian carp, normal-sized Asian carp, so that obviously might change over the course of this next field season,” Wooley said.

Last year, a federal judge rejected a lawsuit filed by other Midwestern states to close river locks in Chicago. Those states said closing the locks would prevent Asian carp from reaching Lake Michigan.