The study was conducted by scientists from the University of Notre Dame, The Nature Conservancy and Central Michigan University.
Laboratory analysis turned up 58 positive hits for the carp in the Chicago Area Waterway System -- a network of rivers and canals linked directly to Lake Michigan -- and six in western Lake Erie, the researchers said.
"The good news is that we have found no evidence that Asian carp are widespread in the Great Lakes basin, despite extensive surveys in southern Lake Michigan and parts of lakes Erie and St. Clair," Notre Dame researcher Christopher Jerde said.
St. Clair Lake is part of a chain of lakes that empty into Lake Michigan.
Some recent reports have suggested birds, boats and other pathways, rather than live fish, were spreading the silver carp DNA.
"Looking at the overall patterns of detections we remain convinced that the most likely source of Asian carp DNA is live fish," Jerde said in a Notre Dame release Thursday.
"It's really very telling that the only places DNA has been recovered are where Asian carp have been captured," he said. "If birds or boats were commonly spreading the DNA, then we should be detecting DNA in other places we have surveyed in the Great Lakes."
The DNA study is part of an effort to find the invasive species when it is at low abundance and can be potentially managed, researchers said.
Laboratory analysis turned up 58 positive hits silver carp in the Chicago Area Waterway System -- a network of rivers and canals linked directly to Lake Michigan -- and six in western Lake Erie."If we wait for the tell-tale signs of Asian carp jumping out of the water, then we are likely too late to prevent the damages," David Lodge of Notre Dame's Environmental Change Initiative said. "Environmental DNA allows for us to detect their presence before the fish become widespread."
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