March of the Asian Carp

On the loose 

Asian carp (bighead and silver) jumping out of the Illinois River near Havana, IL.

Bighead and silver carp (collectively referred to as Asian carp) escaped from Arkansas fish farms into the Mississippi River and have marched steadily upstream in the Illinois River towards Lake Michigan. The invaders reached the Peoria area about a decade ago where their population has been doubling almost every year. In 2003 the Army Corps of Engineers built an electric fence in the Chicago Sanitary and Ship Canal  about 25 miles from Lake Michigan, but soon found it did not stop the Asian carp. So the Corps of Engineers built a second, higher-voltage, barrier that became operational in April 2009 at the same location. By this time Asian carp had been seen less than 10 miles away from the electric fences.

 Approaching the Lakes

Then in December 2009, during routine maintenance of the electric fence (only one lock away from the Lake) a dead bighead carp surfaced when the water was poisoned briefly to prevent fish passage while the power was off. Until this time officials had been skeptical of DNA evidence found at that site and at other locations within 6 miles of the Lake, far past the electric fences. Unfortunately the Corps still remained skeptical and continued to keep the locks open for barge traffic, prompting five Great Lakes states to ask the US Supreme Court to temporarily close the locks connecting Chicago canal system to Lake Michigan. The request for emergency action was denied in January but the case remains before the Court; briefs are due next month.

Only a few hours after the Supreme Court decision was announced, Maj. Gen. John Peabody, commander of the Great Lakes and Ohio River district of the Army Corps of Engineers, revealed that carp DNA had also been found in Lake Michigan waters, beyond the last lock and dam separating the canal from the lake. Holding firm to the Corps’ skeptical position, Peabody was quoted “We don’t know where the fish are… The DNA shows us where they may be.”  The New York Times quoted the leader of the expert team that found the DNA: “I think there’s not another plausible explanation for the presence of DNA that we’ve found other than that there are live fish in the vicinity”. University of Notre Dame Professor David Lodge has been finding Asian carp DNA on the Illinois River side of the locks since August.

Holes in the defense

Biologists and environmental advocates have been frustrated with the reactive stance taken by Army Corps and Illinois officials, and their reluctance to take pro-active precautionary actions. For years it has been known that Asian carp could bypass the electric fence during floods, but only recently has the Corps developed plans to block those passages. Read Prairie Rivers’ comments here.

The Corps continues to operate the fence far below its design voltage, and has not funded experiments that are needed to prove its effectiveness on baby carp or even on large fish during periods when a steel barge passing over the fence distorts the electric field.

While the Corps insists that the DNA test method is new and has not been scientifically validated, conservationists are questioning the wisdom of waiting for traditional sampling techniques to capture a live fish in areas near the Lake where DNA has been found. Electrofishing merely scares rather than immobilizing Asian carps; conventional netting is complicated by the debris-filled bottom of the straight-sided canal; and surface netting after poisoning is difficult because unlike other species, Asian carp sink quickly to bottom.

Turning point

In the face of all this discouraging news, Prairie Rivers Network has intensified efforts to force a major change in the federal policy, which until now has given the benefit of the scientific doubt to the barge industry, not the environment. On Feb. 12 Prairie Rivers board member Clark Bullard reminded a panel of Federal officials in Chicago that measures like electric fences, temporary lock closures and chemical poisons may be necessary in the short term, they are not 100% effective. Since we are unlikely to win a war of attrition against invaders that lay a million eggs at a pop, we must separate the basins as soon as possible. He emphasized that waterborne commerce could still thrive on both sides of the basin divide, with an intermodal freight transfer facility connecting to modern truck and rail networks. It’s time to replace Chicago’s antiquated 19th century transportation, sewage and stormwater systems with 21st century sustainable technology. This may be our last chance to get it right.