A new one-way trap at Rock Run Rookery Preserve in Joliet is designed to keep invasive carp from escaping the lake,

The goal is to make it easier for commercial fishing companies to remove the fish and prevent them from reaching Lake Michigan.

The Forest Preserve District of Will County installed the trap in April.

The pilot project will be evaluated this year as agencies “collaborate to stop the plankton-eating, rapidly reproducing fish from threatening native species and the Great Lakes sport fishing industry,” the forest preserve district said.

The trap will funnel fish toward 9-inch-by-36-inch passages.

The passages consist of gateway “fingers” made of flexible plastic that allow fish to swim in only one direction — they can enter but can’t get out.

The netting is also arranged so fish can’t jump over it, the forest preserve district said.

For more information on the project, go to ReconnectWithNature.org.