Genetic material from a diminutive invasive fish called the Eurasian ruffe has been found at the south end of Lake Michigan. This first-time discovery raises the possibility that a viable ruffe population could migrate into the Mississippi River watershed and compete with native fish there, a scientist said Tuesday.
Researchers conducting water sampling for Asian carp eDNA detected DNA from the ruffe in two samples taken in July from Lake Michigan's Calumet Harbor at Chicago, according to The Nature Conservancy.
No live ruffe were seen during the sampling. State and federal officials are downplaying any chance that the DNA discovery signaled a significant presence of the exotic fish, all while urging anglers to be on the look-out. There is also the chance that the Eurasian ruffe could be close to using the Chicago canal system to invade the Mississippi.
The manmade, engineered network of canals and rivers around Chicago has become the flashzone in a debate over invasive species. Several states have urged federal courts to order measures that would disconnect links between the Great Lakes and Mississippi systems, preventing fish and other organisms from moving between them. Under orders from Congress, the U.S. Army Corps of Engineers (USACE) has pledged to produce a list of possible options by early next year, including use of water cannons, physical barriers and other nonsense. The best solution would be to physically separate the Chicago Sanitary Canal from the Great Lakes - i.e. disconnect the shipping channel.
Asian carp have been moving up the Mississippi River over the last few decades. Originally stocked for algae control in catfish farms and wastewater lagoons, heavy floods and broken levees allowed them to escape into the Mississippi River system, where they've thrived and expanded. Their self-sustaining populations are now knocking on the door to the Great Lakes, a series of canals through the Chicago area. In the latest of a series of pointless expenditures, the US government has spent almost $200 million to shield the Great Lakes, focusing primarily on an electrified barrier in these waterways, which connect the carp-infested Mississippi River watershed to Lake Michigan. Per usual, more is needed here - namely, a physical separation of the two systems. Due to the amount of shipping traffic and commerce that pass through these canals, such a solution is highly unlikely. So the potential future of the Great Lakes hangs in the balance. Could this be another example of closing the barndoor after the herd has escaped?
Many users of the Great Lakes believe that if it hasn't happened already, the Asian carp could be making an invasion any day now. Incidentally, on a recent fishing trip in Kansas, Chris Jones was telling me about the sheer number of Asian carp in the Missouri River is staggering. Local catfish guides frequently use them for bait, and catching bait is as simple as pulling into a slack spot and revving the outboard. He told me to get ready - having grown up in the area, Chris has seen their numbers swell, from a few fish here and there to a total nuisance that makes some pleasure boaters cocoon their pontoon boats in chain link fencing. "It's inevitable," Chris told me, " you will have them in the Great Lakes before anything is done to prevent it." Sadly, I will not be surprised when this happens - I believe that "if" left town years ago.
While not a species with the potential to impact the entire Great Lakes ecosystem, the Eurasian ruffe is one of 29 species the USACE has identified as leading candidates to migrate between the two systems. A distant cousin to the yellow perch, the ruffe is believed to have hitchhiked a freighter's ballast tanks from Europe to Lake Superior's Duluth Harbor in the early 1980s.
Since its introduction, the ruffe has spread across Lake Superior and to small areas in northern Lake Michigan and Lake Huron. In these locations, it competes for food with perch and walleye, two species higly prized for sport and commercial purposes. In spite of the competition, the U.S. Fish and Wildlife Service says that native species don't appear to have been significantly harmed. Whether this is truth or another attempt to downplay another invasive species in the Great Lakes remains to be seen.
The Nature Conservancy, the University of Notre Dame and Central Michigan University have been sampling Great Lakes tributaries and bays since 2009 for genetic fingerprints of invasive fish. Asian carp eDNA has been detected in the Chicago waters, as well as tributaries to Lake Erie (Maumee Bay and Sandusky River). Aquatic creatures (such as fish) deposit eDNA in the water as mucus secretions (slime), scales and body wastes. Army Corps scientists say it also can be transported on boat hulls, fishing nets, or in bird feces.
Kevin Irons, aquatic nuisance species program manager for the Illinois Department of Natural Resources, said it's not surprising that Eurasian ruffe DNA would turn up in Calumet Harbor, with its heavy commercial shipping traffic. State agencies monitor the harbor with electrofishing and nearshore waters of Lake Michigan with nets.
"To date, we have not captured any ruffe, and in fact we don't believe Eurasian ruffe are established anywhere in southern Lake Michigan," Irons said. While this may be of some small comfort to Great Lakes residents, the simple fact has been demonstrated that any invasive species is indicative of a major problem. This problem, the Eurasian ruffe, just happens to be smaller than some of the others.