Vexing Asian Carp Likely Spread To Great Lakes

Asian carp, an invasive fish species known to unravel entire food chains by devouring resources and breeding rapidly, have likely found their way into the Great Lakes, according to an Associated Press report on a recent study, which refutes a government analysis which downplays the plausibility of the troublesome fish living the Great Lake system.

"I would say there's at least some evidence for Asian carp being present in southern Lake Michigan,"  Christopher Jerde of the University of Notre Dame, the lead author of the study, told The Associated Press. "The question is how many."

The Asian carp is seen as a threat because of its capability to out-compete more valuable commercial and sport fish. Of greatest concern is the silver and bighead carp, which feast on plankton and reproduce prolifically.  

The pesky fish reportedly made their way out of southern ponds in the 1970s and have been migrating northward since.

Jerde and his team reportedly extracted DNA from 2,800 water samples taken around the Great Lakes and extracted matter the fish shed through excrement, scales and body slime, a substance called environmental DNA, or eDNA. The eDNA analysis found 58 positive DNA matches for silver or bighead carp in the Chicago Area Waterway System, which is linked to Lake Michigan.  

However, researchers came up empty-handed when searching areas in Chicago's water system where Asian carp were expected to be found, which leaves some room for doubt of their eDNA analysis.

"Sure, it could be live fish and it also could be these other things" such as excrement from birds that fed on carp in distant rivers, said Kelly Baerwaldt, a fisheries biologist and Asian carp program manager for the Army Corps, in the AP report.

"The bottom line is there's just a lot we don't know about eDNA," she said.

This study comes on the heels of another which concluded that Asian carp are capable of breeding in waterways once thought too small to support the fish. 

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