Army Corps: Fish can breach Chicago barrier

DETROIT — Schools of small fish are capable of crossing an electrical barrier designed to keep Asian carp from using the Chicago ship canal to enter the Great Lakes, according to a new research report from the U.S. Army Corps of Engineers.

There is no evidence that Asian carp are bypassing the barriers, which were established to prevent billions of dollars in potential damage to the Great Lakes fisheries, according to the report released by the Army Corps’ Chicago office.

But the research shows that passing vessels can pull the fish past the barriers while also causing fluctuations in the electrical field, the report said. It was released Friday.

“Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength,” the report said. “Additionally, the preliminary ... findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools.”

The Army Corps of Engineers and the U.S. Fish and Wildlife Service have conducted both laboratory and field experiments to “assess the potential impacts of barge tows traversing the electrical dispersal barrier system” in the canal.

The report said there is no sign of an immediate threat of Asian carp traveling through the canal, which links the Mississippi River watershed to the Great Lakes.

“There is no evidence that Asian carp are bypassing the barriers. Nor is there any indication that Asian carp are in the vicinity of the barriers,” it said. “The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan.”

More study is needed to learn more about how well the electrical barrier is functioning, the report said.

“Future research will include a variety of simulations to further evaluate fish behavior, effects of the electrical field on groups of fish and how these may relate to operational protocols of the barriers and navigation within” the Chicago Sanitary and Ship Canal, it said.

The electrical barrier is meant to block Asian carp’s path toward Lake Michigan. Just one live Asian carp has been found beyond that point, although numerous DNA samples have turned up past the barrier and in Lake Erie.