Chicago Fish Fence Fails to Deter Giant Asian Carp

State and federal agencies acknowledged Friday that DNA tests show Asian carp have evaded a two-part electric barrier intended to prevent the fish from gaining access to Lake Michigan, and eventually the Great Lakes ecosystem, through the canal, a man-made waterway that provides a direct hydraulic connection between Lake Michigan and the Mississippi River Basin.

Scientists and government officials agree the invasive fish pose a serious environmental threat to the Lakes because of their size and voracious appetites. The two invasive species - bighead carp and silver carp - can grow over four feet long and 100 pounds and quickly take over habitat upon arrival. In the Illinois River, they now make up 90 percent of the life forms present in some stretches of the river.

On November 17, scientists at the University of Notre Dame notified the U.S. Army Corps of Engineers that some water samples, taken from the area between the electric barriers and Lake Michigan on September 23 and October 1, tested positive for the presence of Asian carp. The positive samples were from an area about one mile south of the O'Brien Lock, about eight miles from Lake Michigan.

U.S. Fish and Wildlife Service staffer Eric Leis holds an invasive Asian silver carp caught in the Illinois River. (Photo courtesy USFWS)

The fish kill is necessary now, officials say, because the Corps is planning to perform semi-annual scheduled maintenance on Barrier IIA, one of the two electric barriers presently in operation on the Chicago Sanitary and Ship Canal.

During the maintenance shutdown, Barrier I will remain active. But because of concern that Barrier I may not be effective in deterring juvenile fish, the fish toxicant rotenone will be applied to the canal between the barrier and the Lockport Lock and Dam.

"Scheduled barrier maintenance will proceed as planned," said Major General John Peabody, commanding general of the U.S. Army Corps of Engineers, Great Lakes and Ohio River Division. "This new information reinforces the importance of preventing any further intrusion of the Asian carp via the largest pathway, the Chicago Sanitary and Ship Canal."

The application of rotenone is planned for December 3, and crews from the IDNR and other agencies will remove fish from the canal and dispose of them in a landfill.

The fish habitat in the section of the canal scheduled for treatment is made up of mostly non-sport fish with the most common species being common carp, goldfish, and gizzard shad. Before the application of rotenone, an electro-fishing operation will be conducted to relocate as many sport fish as possible. Rotenone dissipates quickly on its own, but to accelerate that process a neutralizing agent known as potassium permanganate will be used following the application.

Rotenone poses no threat to humans or wildlife other than fish in the canal at the time of the release, officials said.

"Keeping Asian carp from reaching Lake Michigan remains the focus and goal of the Illinois Department of Natural Resources and the Rapid Response Work Group. We will continue to work with the group and our partners on how best to address this new issue and move forward with achieving our overall goal," said IDNR Assistant Director John Rogner.

The announcement that Asian carp have gotten past the electric fish fence is "sobering, but predictable," said Henry Henderson, director of the Natural Resources Defense Council’s Midwest Program and a former Commissioner of the Environment for the City of Chicago. "The responsible federal and state agencies have known about this problem for 13 years, but have utterly failed to act with the urgency that this threat requires."

"The prospect of 100 pound fish off of Oak Street Beach and leaping out at boaters in the Great Lakes should spur action that should have been undertaken years ago," Henderson said. "We have seen how zebra and quagga mussels have literally transformed Lake Michigan, and I fear that the Asian carp could do far worse to the ecosystem."

Henderson urges that physical barriers be placed in the waterways. He says the Chicago Diversion should be closed off and the ecological barriers that used to protect the Great Lakes from these threats should be restored.

"The only thing aggressive about the virtual fish fence has been its multi-million dollar price tag," he said.

Two species of Asian carp - the bighead and silver - were imported by catfish farmers in the 1970s to remove algae and suspended matter from their ponds. During floods in the early 1990s, many of the catfish farm ponds overflowed their banks, and the Asian carp were released into local waterways in the Mississippi River basin.

The giant carp have made their way northward up the Mississippi River, becoming the most abundant species in some areas of the river. They out-compete native fish, altering the ecosystem.

The multi-agency Asian Carp Rapid Response Workgroup will focus on Asian carp eDNA sampling and other monitoring efforts on areas upstream of the barrier to gather near real-time data on the current location of Asian carp to aid the team in planning to control the carp.

"Protecting and restoring the Great Lakes is one of U.S. Environmental Protection Agency’s highest priorities," said Cameron Davis, senior advisor to U.S. EPA Administrator Lisa Jackson on the Great Lakes. "The plan announced today reflects a difficult, but critical team effort to protect the lakes against a destructive fish that could cause catastrophic damage to the Great Lakes ecosystem."

If Asian carp become established in the Great Lakes, they could cause a catastrophic decline in native fish species and severely damage the Great Lakes sport fishing industry, valued at $7 billion.

The Asian Carp Rapid Response Workgroup includes the Illinois Department of Natural Resources, U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, U.S. Coast Guard, USDA Animal and Plant Health Inspection Service, Chicago Department of Environment, Metropolitan Water Reclamation District of Greater Chicago, Midwest Generation, Great Lakes Commission, Great Lakes Fishery Commission, International Joint Commission, and Wisconsin Sea Grant.

Fisheries management agencies from Indiana, Wisconsin, Michigan, Minnesota, Ohio, Pennsylvania and New York are also providing support to the operation.

Copyright Environment News Service (ENS) 2009. All rights reserved.