Asian carp DNA found in Green Bay's Fox River

GREEN BAY, Wis. - Asian carp DNA has been found in the Fox River in downtown Green Bay but the source of the invasive fish's genetic material is unclear, Wisconsin wildlife officials said Tuesday.

A single positive sample for silver carp was identified from 200 samples taken this summer in the Fox, a tributary of Lake Michigan, the state Department of Natural Resources said.

The discovery by the U.S. Fish and Wildlife Service was in the heart of the city and was part of a survey that started at the mouth of the river and ended about five miles upstream, the Milwaukee Journal Sentinel (http://bit.ly/1nynTNX) reported.

"It's important," DNR aquatic invasive species coordinator Bob Wakeman said. "But we don't want to jump to conclusions that Asian carp are there."

Wakeman said the DNA could have come from a live fish, but it's more likely to have come from a bait bucket or the hull of a boat that had been in waters where Asian carp now inhabit. Another possibility is feces from birds that flew from waters with Asian carp.

The sampling on the Fox is part of a survey of rivers being conducted by the Fish and Wildlife Service looking for evidence that Asian carp may have invaded Lake Michigan.

Scientists have been testing waters for Asian carp DNA in an effort to track the hungry, aggressive invaders' progress toward the Great Lakes. Bighead and silver carp have been migrating northward since they were imported to the Deep South from Asia in the early 1970s and escaped into the Mississippi River.

In November, the Wisconsin DNR reported that a sample of a silver carp had been found by a team from Notre Dame University near Potawatomi State Park, where Sturgeon Bay opens to Green Bay. Subsequent testing in the area failed to turn up any new positives.

Silver carp is known for its leaping ability. The bighead is larger and can grow to 110 pounds. Both consume large amounts of plankton, a crucial source for native fish and other aquatic life. Scientists fear that the spread of Asian carp will cause irreparable harm to the lake's food web.