Invasive Species

Asian carp knocking on the back door

A new monitoring technique being used by the U.S. Army Corps of Engineers indicates that invasive Asian carp are a mere 7 miles from the electric barrier in the Chicago Sanitary and Ship Canal. This places the edge of the invasive fish population 10 miles closer to the barrier—and consequently the Great Lakes—then previously determined by traditional monitoring techniques such as electro-fishing.

The Corps recently began working with the University of Notre Dame to detect the presence of Asian carp through a new DNA test of water samples taken below the barrier. The tests are detecting positive results for the silver carp in locations where traditional techniques have failed to find the fish.

The Asian carp are invasive fish that are harming the environment and economies of the Mississippi and threaten to do the same to the Great Lakes. The term captures four different species of fish- the bighead, black, grass and silver carp. They are voracious filter feeders that can grow to more than 3 feet long and quickly come to dominate a waterbody. They would cause irreversible harm to the Great Lakes by consuming large quantities of algae and zooplankton, muscling out native fish populations. Meanwhile, the giant fish’s tendency to jump out of the water when startled makes them a hazard to boaters.

The electric barrier is located near Romeoville, Illinois on the Chicago Sanitary and Ship Canal. The barrier sends one volt of electricity continually through the waters, an attempt to repel invasive fish species like the Asian carp from migrating between the basins. The canal itself is a man-made waterway that connects Lake Michigan to the Mississippi River basin. Originally intended as a means for the city of Chicago to overcome sewage problems in the early 20th century, it created an artificial connection through which aquatic invasive species can pass in both directions. This is the only waterway connecting the two basins.

There are three actions that should be taken to stop the carp from invading the Great Lakes. First, the voltage of the barrier can be turned up immediately. Currently the Corps is not operating the barrier at full power due to safety concerns for commercial and recreational canal users. The Corps quickly began safety testing of increased “operating parameters,” including operating the barrier at 2 volts and changing the pulse and frequency of the electric current. At press time, a decision to strengthen operating parameters had not yet been made. Given the imminent crisis, the barrier can, and should be, operated at its highest power setting, four volts.

Second, aggressive monitoring must take place for the remainder of the fish migratory season. If the carp are found past predetermined points, the Illinois Department of Natural Resources, working with a group of invasive species experts from around the region, should quickly implement an emergency rapid response plan that they have been developing for over 10 years. Such a plan would probably include an application of a piscticide – fish poison – to knock the population back to a safer distance in the short term. Rapid response should not be considered the long term solution to keeping the Asian carp out of the Great Lakes.

Thirdly, when the Water Resources Development Act was passed in 2007 the Corps was authorized by Congress to determine how to restore hydrologic separation between the Great Lakes and Mississippi River basins and solve this problem once and for all. The Corps must quickly complete and implement a hydrologic separation plan, because we can’t rely on a barrier which isn’t foolproof, inconsistent monitoring results, and chronic chemical treatment as our only lines of defense.

Sidebar: Disconnection
Coalition member, Alliance for the Great Lakes, has explored preliminary feasibility studies for disconnecting the Great Lakes from the Mississippi basin. Their report identifies five scenarios for complete or partial ecological separation of the basins. This would halt the transfer of Asian carp, as well as other invasive species, between the two watersheds and is a critical piece of invasive species prevention and Great Lakes restoration. The full report is available at www.greatlakes.org/invasives/ecosep.

© 2009 Great Lakes News.