Bracing for Carp in Great Lakes, but Debating Their Presence

By MICHAEL WINES, NYT

After decades of increasingly dire warnings, countless studies and countermeasures, scientists are beginning to mull over hints of something that few of them wish to contemplate: The despised Asian carp may have finally arrived in the Great Lakes.

“May have” are the operative words. The latest hint consists of a single water sample, one of scores taken last May from Lake Michigan, that tested positive for remnants of DNA from one particularly destructive species, silver carp. Experts debate the significance of that one hit, which was disclosed in late October, and a thorough resampling of the same waters in November turned up nothing, scientists were told late last month.

But the sample came atop a handful of other clues, some dating to the 1990s, that suggest that the silver carp and a similarly nasty cousin, the bighead, may be coming to parts of the lakes. On Monday, the Army Corps of Engineers will issue a lengthy study proposing ways to keep the carp and other invasive species, now common in the Mississippi and Ohio River basins, from migrating into the lakes at points where their waters are linked.

The positive sample was collected in Sturgeon Bay, a small indentation in a finger of Lake Michigan that includes Green Bay, Wis., during a month when the carp are active. False positives can occur if a sample is contaminated, but experts largely agree that the material actually came from a silver carp.

(More here.)