When the U.S. Army Corps of Engineers delivered long-awaited recommendations for dealing with the threat of the Asian carp to the Great Lakes, policymakers in the region felt somewhat let down. And understandably so. How best to halt the northward migration of the voracious fish into the Great Lakes has been a contentious debate for years with high economic and political stakes. If policymakers hoped the corps would narrow the choices by pointing to a recommendation or two that would best keep out the destructive fish, what they received last month fell short of settling the debate as the report laid out eight possible options.
In light of that, a new study by the University of Notre Dame, Resources for the Future, an independent research group, and the U.S. Forest Service has advanced the discussion, providing critical information on the potential effectiveness of different options, all of which should facilitate decision-making. The study released last week rated about 17 strategies to counter the carp threat, including the system of electric barriers, physically closing the shipping lanes from the Mississippi to the Great Lakes and deploying strobe lights, sounds and bubbles.
To no one’s surprise, the study confirms that physical, or hydrologic, separation of the lakes from the Chicago Sanitary and Ship Canal and the Mississippi would be most effective at protecting the freshwater lakes, with the potential to prevent 95 percent to 100 percent of Asian carp from entering Lake Michigan. The electric barrier system now in operation is 85 percent to 95 percent rate effective.
The rub, as the corps also has emphasized, is that separation will be the most expensive (estimated at $18 billion) and take about 25 years to accomplish. A permanent response is imperative to reverse the threat to the lakes’ ecosystem and a $7 billion fishing and tourism industry. Scientists already have found traces of bighead and silver carp DNA much closer to the lakes than anticipated. The time to begin the complex process of separation is now, with the Great Lakes states negotiating a formula to share the costs of strengthening the electric barriers in the interim, while the carp are still some distance out.