Great Lakes Fishery Commission spokesman Marc Gaden said after genetic testing showed evidence of the carp nearing the electric barrier, the power on the barrier was increased to keep the fish out, the Detroit Free Press said Monday.
"These carp are clawing at the door now," Gaden said.
The silver carp, which experts estimated to be at least 15 miles from the barrier in June, could pose a significant threat to the Great Lakes due to their high reproduction rates and the fact they feed on tiny plankton.
"These carp have the potential to be every bit as devastating as the worst invasives we have seen -- sea lamprey and zebra mussels," Gaden said. "That's what we're worried about."
Col. Vincent Quarles, commander of the Army Corps of Engineers' Chicago District, told the Free Press it remains unclear whether the increased voltage at the electric barrier would keep the carp at bay.
"It's not a silver bullet, but it's the best tool we have," he said.