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CMU expert responds to silver carp environmental DNA found in Kalamazoo River

Great Lakes research scientist and eDNA detection pioneer Andrew Mahon weighs in


Detecting the presence of silver carp in the Kalamazoo River by screening water samples for environmental DNA affirms the efficacy of a technique developed by Andrew Mahon, Central Michigan University Institute for Great Lakes Research scientist and assistant professor of biology.

“While the sample that tested positive for the presence of silver carp eDNA is not necessarily indicative of a large population living in the Kalamazoo River, this is the first sign of the fish being detected this far north in a river that flows into Lake Michigan,” Mahon said.

“Having detected these fish with similar eDNA tools in water samples taken from Lake Michigan near the Chicago area during 2009 through 2011, it is not surprising that the detections of DNA from these fish are moving up to northern tributaries,” Mahon said.

Mahon is one of the scientists who pioneered the eDNA detection methods used by Michigan Department of Natural Resources and U.S. Fish and Wildlife Service officials, who yesterday announced the presence of silver carp in the lower part of the river just below the Caulkins Dam in Allegan County.

Asian carp, including bighead and silver carp, pose a significant threat to the Great Lakes ecosystem and Michigan’s $7.5 billion commercial and sports fishing industry. The fish are known to quickly reproduce and compete with other native and recreational species.

Critics opposing the use of the eDNA detection technique have suggested that birds, boats and pathways other than live fish are spreading the carp DNA found in the Great Lakes, even though no scientific, peer-reviewed data substantiate these claims.

“Previously published studies where eDNA has been found close to locations where fish have been physically caught have convinced us that the DNA we are detecting is coming from live fish and not from other sources such as bird excrement, boats and sewage outflows,” Mahon said.

“If we listen to the naysayers who claim that more research is necessary to validate the eDNA technique, we will miss the opportunity to stop an invasion of silver and bighead Asian carp. Once these fish are present in sufficient numbers to be detected by conventional techniques, it will be too late.”

One of 200 samples taken from the lower part of the Kalamazoo River tested positive for silver carp eDNA, indicating that an Asian carp invasion may be starting in the Great Lakes.

“The proactive efforts by MDNR and USFWS of additional, targeted water sampling using multiple detection methods, including eDNA, are directly in line with what my research colleagues and I are doing,” Mahon said. “We began DNA studies to provide management agencies with another monitoring tool to assist them with keeping invasive species out of the Great Lakes. The eDNA technique is extremely effective for early detection and prevention.”

Central Michigan University is a recognized leader in studying the Great Lakes, with more than 20 faculty in the Institute for Great Lakes Research supported by state-of-the-art facilities in Mount Pleasant and at the CMU Biological Station on Beaver Island. A $95 million Biosciences Building due to be completed in 2016 will provide enhanced infrastructure to support faculty and student research and classes.​

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