Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=153543
Story Retrieval Date: 6/18/2013 1:31:54 AM CST
The U.S. Army Corps of Engineers is identifying the latest responses to the threat Asian carp pose to Lake Michigan.
A spokeswoman for the Army Corps said Wednesday that officials are trying to determine the next step in carp prevention. “They’ll try and do electrofishing and netting to capture carp and confirm what the eDNA [environment DNA] tests show,” she said.
Electrofishing stuns fish and allow them to be caught alive.
The presence of carp DNA found in the North Branch of the Chicago River near the Wilmette pumping station, located on the lakefront has heightened concerns that carp may be close to invading Lake Michigan.
The actions by the Army Corps and other government agencies are trying to prevent the migration of carp into the Chicago Sanitary and Ship Canal, another entry into Lake Michigan.
“Actions underway include construction of measures to prevent the fish from entering the Chicago Sanitary and Ship Canal from the Des Plaines River or Illinois and Michigan Canal during heavy rains,” according to a spokeswoman for the U.S. Army Corps.
The spokeswoman said other potential bypass sites are being researched.
Fences made of a combination of concrete and metal will be erected to prevent water flow that can carry fish from the Des Plaines River into sanitary and ship canal during floods.
Construction of a second electric barrier in the canal will be completed in the fall. This barrier will serve as a second half of the barrier activated last April. The barriers produce an electrical field in the water to keep fish from swimming past a certain point.
The Army Corps announced Tuesday that carp DNA was found closer to Lake Michigan than previous tests have shown.
“eDNA samples indicate that there may be live Asian carp, but how the particles got there is not known,” said Maj. Gen. John Peabody of the Army Corps earlier this week.
However, carp DNA can be washed into the waterways through sewage or using carp at bait, which can cause test results to be misleading.
Peabody reported that samples taken in late October detected carp DNA in the canal close to the Wilmette pumping station. Past test results also show positive DNA presence in the Calumet-Sag Channel near the O’Brien Lock and Dam and the Des Plaines River north of the electric barrier.
“eDNA is an important tool to identify carp,” Jo-Ellen Darcy, Assistant Secretary of the Army for Civil Works, said at a press briefing Tuesday. “Net monitoring will continue to confirm there is a carp presence.”
The announcement was made during a media briefing at the Shedd Aquarium in Chicago hosted by U.S. Senator Dick Durbin, D-Ill., and Congresswoman Judy Biggert, R-Ill., as Illinois faces a lawsuit in the U.S. Supreme Court.
The lawsuit filed by Michigan and joined by several other states seeks to force the closure of Chicago’s shipping locks that connect the sanitary and ship canal to the lake.
“We are very concerned about the threat to our Great Lakes,” Biggert said. “We hope states would join us instead of suing us in the long efforts made to contain the fish.”
The Army Corps sponsors the eDNA testing that was developed at the University of Notre Dame.
Tests determine whether there could be any carp in the water by detecting DNA through slime, feces, urine and scale particles. Tests cannot, however, confirm the presence of live fish.
Winter makes it difficult for a thorough search to be conducted, and Army Corps officials said the ice will have to thaw before boats can investigate the waterways where carp DNA was detected.
Despite eDNA evidence of a potential carp presence near Lake Michigan, Richard Lanyon of the Metropolitan Water Reclamation District of Greater Chicago said he remains skeptical of an imminent carp invasion.
“The eDNA test is an indicator and is not a positive test for the presence of carp,” said Lanyon, the executive director of the district. “Since we haven’t seen any carp upstream of the barrier I don’t think it’s as much of a threat as people think it is.”