If Asian carp aren’t in the Great Lakes, they can’t get much closer. Sampling of the Chicago Area Waterway System (CAWS) last fall revealed carp eDNA throughout the system, including near a lock in downtown Chicago, just one block from Lake Michigan.
“Prevention needs to happen now and the U.S. Army Corps of Engineers and other key decision-makers should take swift action,” said the non-profit Alliance for the Great Lakes (AGL), which charges that the Corps lacks direction, as revealed in its Great Lakes-Mississippi River Interbasin Study.
“DNA evidence is an early detection tool to understand the potential movement of carp, and testing results have consistently found DNA hits on a path closer and closer to the Great Lakes over the past several years of testing,” the group added.
The Corps report outlined eight possible ways to stop migration of Asian carp into the Great Lakes, with the most expensive being an $18.3 billion separation of the CAWS from Lake Michigan. Meanwhile, the Alliance supports measures to temporarily reduce risk, including construction of a new channel and control technologies in the approach to Brandon Road lock and research on reconfiguration of locks in general.
But long-term issues with Chicago’s water system infrastructure must be addressed to keep the carp out, emphasized Jennifer Caddick, AGL spokesperson.
“It’s complicated. You can’t just build one dam and solve the whole problem,” she said. “There’s a lot of work to be done, but we need intensive focus.”
If/when Asian carp become established in the Great Lakes, consequences could be catastrophic for the multi-billion-dollar sport fishery. That’s because the exotic fish are fast-growing, prolific, plankton eaters. They likely would outcompete the many young and adult native fishes that rely on phytoplankton and zooplankton for their primary forage.
Additionally, the U.S. Geological Survey has identified 22 rivers in the U.S. portion of the Great Lakes that would provide suitable spawning habitat for Asian carp.