TRAVERSE CITY, Mich. (AP) – Federal crews have discovered two Asian carp in the Illinois River, 12 miles closer to Lake Michigan than where others of that size previously were seen.

U.S. Fish and Wildlife Service teams found two silver carp about 6 { inches long late last month in the river’s Marseilles Pool near Seneca, Illinois.

That means the leading edge of the river’s juvenile Asian carp population is about 66 miles closer to Lake Michigan than it was at the beginning of this year.

Still, officials say there are still 76 miles of water, three locks and dams and an electric barrier between the juvenile carp and the lake, although some adults are closer.

Officials are debating how to protect the Great Lakes from Asian carp, which scientists say could harm native fish.