SENECA, Ill., Nov. 2 (UPI) -- Silver carp, a species of Asian carp, have been found in Illinois waterways closer to Lake Michigan than ever before.
Fears that Asian carp might someday breach the barriers protecting Lake Michigan and the rest of the Great Lakes from the invasive species.
Conservationists and fisheries managers have warned against the potential ecological and economic damages of the carp ever since biologists first observed the invasive species creeping up the Mississippi.
Every few months, the carp offer fresh warnings that they're getting closer.
The latest shot across the bow comes from the U.S. Fish and Wildlife Service, which late last month found two juvenile Asian carp in the Illinois River, 12 miles closer to Lake Michigan than the last time researchers surveyed the waterway.
Sampling crews found the two silver carp, each just over six inches long, in the Marseilles Pool of the Illinois River. Researchers with USFWS are not conducting genetic tests to determine how old the fish are and where exactly they spawned.
"This finding brings the leading edge of juvenile Asian carp detections about 66 miles closer to Lake Michigan than it was at the beginning of 2015," the Asian Carp Regional Coordinating Committee announced in a news update.
The fish aren't exactly knocking on Lake Michigan's door. Three locks and dams, as well as several electric dispersal barriers and 76 miles of water, lie between Marseilles Pool and the lake. But some conservationists worry the fish could get pulled through the locks in the wake of large ships. The Army Corps of Engineers, who built the locks, have acknowledged the possibility in numerous reports, as have studies by the Fish and Wildlife Service.
Local regulators and federal agencies continue to debate how best to stop the carp and who will foot the bill. State lawmakers in Michigan, Illinois and Ohio have urged the Corps to take more aggressive action to thwart the invasive fish.
Many are opposed to a proposal to physically separate Lake Michigan from waterways around Chicago -- a plan the Corps says would take 25 years to complete and cost $18 billion. For now, electric barriers will have to do.