CHICAGO (AP) — The electric barrier designed to keep Asian carp out of the Great Lakes may need more voltage to stop the smallest of the invading fish, according to a report issued Friday by the Army Corps of Engineers.
Small carp won’t be stopped by the current voltage used at the barrier on the Chicago Sanitary and Ship Canal, officials said.
Tiny carp aren’t near the barrier yet, so the power doesn’t need to be raised immediately, Corps officials said. The agency will conduct more research before a final decision on the barrier is reached, said Maj. Gen. John Peabody, the Corps’ division commander for the Great Lakes.
Turning up the voltage could pose safety risks to barges and others near the canal, officials said.
“We will continue to assess and validate this information and are prepared to make changes to the operating parameters as evidence warrants,” Peabody said in a news release.
State and federal officials have long waged a battle against Asian carp, which have steadily migrated up the Mississippi River and threaten to invade the Great Lakes.
Bighead and silver carp, Asian varieties that escaped decades ago from Southern fish farms and sewage plants, have migrated northward and reached the canal, which connects the Mississippi with the Great Lakes. Scientists have found Asian carp DNA in water samples taken from Chicago-area rivers and canals.
Asian carp could starve out competing fish and threaten the $7 billion commercial and sport fishing industry, biologists say.
The Corps believes the current barrier, about 25 miles south of Lake Michigan, can keep out carp larger than 5.4 inches.
But lab experiments showed that carp between about 2 to 3 inches in length weren’t stopped by the same voltage used at the barrier. Tiny carp might not absorb enough current to be stopped, officials said. Bighead carp, the kind used in the tests, can eventually grow past 5 feet.
The tiny carp aren’t an imminent threat because the nearest carp of the size in the tests were more than 100 miles from the barrier, officials said. Carp populations that could reproduce were about 25 miles away.
The lab tests suggest that an increase in voltage, from 2 volts per inch to 2.3 volts, might be needed at the barrier. But increased power could endanger barges moving flammable items across the canal, said Ernie Drott, the chief of the Corps’ Great Lakes program support division.
Peabody said more research would be needed to confirm the lab results. “The laboratory cannot replicate the scale or the scope” of the barrier, he told reporters Friday.
A larger report on the barriers is expected to be released later this year.
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