TRAVERSE CITY (AP) – Analysts have discovered more genetic material from Asian carp beyond an electric barrier designed to prevent them from invading the Great Lakes, renewing a debate over the federal government’s strategy for protecting the region’s waters from the voracious fish.
The U.S. Army Corps of Engineers reported this week that nine water samples taken in May and June from Chicago-area waterways contained DNA from silver carp, one of the Asian species threatening to enter the lakes after migrating northward for decades in the Mississippi River and its tributaries. That brings to 81 the number of positive DNA hits beyond the barrier since sampling began in 2009.
Hundreds of other samples taken in the area have contained no carp DNA. Still, environmentalists said the findings showed the barrier in the Chicago Sanitary and Ship Canal, the man-made linkage between Lake Michigan and the Mississippi basin, isn’t getting the job done. They favor construction of physical barriers to sever ties between the two watersheds.
“The Army Corps and a number of other agencies have tried very hard to convince the public that their efforts have gotten the problem under control,” Thom Cmar, an attorney with the Natural Resources Defense Council, said Thursday. “It’s clear that there are still some (Asian carp) present in the waterway system and we need to be acting more quickly to permanently solve the problem.”‘
Michigan Attorney General Bill Schuette said the federal government needs to speed up its long-range analysis of how best to stop aquatic species from migrating between the Great Lakes and other water systems, where they compete with native species for food and habitat.
“We don’t need any more studies,” Schuette said. “We need to act.”
John Goss, the Obama administration’s Asian carp program coordinator, told The Associated Press it remains unclear whether the “environmental DNA” findings signal the presence of live fish – and if so, how many. The genetic markers could have come from dead fish or from bilge water picked up by boats on the other side of the barrier, which consists of three separate electric fields, he said.
Measuring the effectiveness of the barrier network, about 25 miles from Chicago, is a top priority this year for the government’s Asian carp task force. Technicians have implanted ultrasonic transmitters in 166 fish on both sides of the electric field to trace their movements and none have passed through, Army Corps spokeswoman Jacqueline Tate said.
Underwater sonar cameras have recorded images of some fish approaching the barrier but none traversing it or even making the attempt, Goss said.
“All the information we have is that the barriers are effective,” he said.
Seven of the nine water samples that tested positive for silver carp DNA were taken in Lake Calumet on Chicago’s South Side, Tate said. Lake Calumet, linked to a river that flows into Lake Michigan, is where the only live Asian carp found beyond the barrier was netted in June 2010. The other two samples came from the Chicago River.
Federal agencies have taken two additional sets of water samples from those areas as required by their “rapid response plan.” Both are being tested to determine whether additional measures such as spreading fish poisons or stepped-up commercial netting are needed, a spokeswoman for Goss said.
The Army Corps and other agencies are planning to complete their study of possible invasive species solutions – including separation of the Great Lakes and Mississippi basins – in 2015. Critics say that’s too slow. A federal lawsuit filed by Michigan, Minnesota, Ohio, Pennsylvania and Wisconsin demands quicker action.
Legislation pending in Congress would require the Army Corps to report within 18 months on the feasibility of separating the two systems. The Alliance for the Great Lakes, an environmental group based in Chicago, urged supporters Thursday to lobby their representatives to support the bill.
Experts disagree on how damaging bighead and silver carp would be to the Great Lakes. Some say the aggressive filter feeders, which eat plankton that forms a crucial link in the food chain, would jeopardize the $7 billion fishing industry. Others say the lakes’ cold waters and a lack of suitable food would limit their spread.
(Copyright 2011 by The Associated Press. All Rights Reserved.)