TRAVERSE CITY, Mich. (AP) — Another search for Asian carp will take place in
Chicago-area waters next week following more discoveries of their genetic
material close to Lake Michigan, officials said Tuesday.
DNA from silver carp, one of the Asian species threatening to invade the
Great Lakes and compete with native fish for food, showed up in samples
taken from a waterway called the North Shore Channel between June and
September. Of 171 samples collected, 17 tested positive. Also, a single
positive hit was recorded in the nearby Chicago River.
Scientists don’t know whether so-called environmental DNA, or “eDNA,”
signals the presence of live fish or could have come from another source,
such as bilge water from ships or feces from fish-eating birds. But
government policy requires an intensive search whenever three consecutive
rounds of sampling yield positive results.
“This is part of the ... control strategy that includes continuing
aggressive monitoring to keep Asian carp out of the Great Lakes, developing
cutting edge control technologies, and refining the use of eDNA,” said John
Goss, who coordinates the Obama administration’s Asian carp program through
the White House Council on Environmental Quality.
The Oct. 16-19 search will cover the North Shore Channel and a 6-mile
stretch of the Chicago River beginning near the downtown Chicago lock.
Commercial fishing crews will be deployed and teams will place nets in the
waters. Government workers will use electric stunning devices to catch fish
in shoreline areas and chase others toward the nets.
The hunt will be the third triggered by three consecutive eDNA sample sets.
The others were in Lake Calumet, another Chicago-area waterway — one in 2011
and one this year. Neither turned up any Asian carp.
Just one actual carp has been found beyond an electric barrier 37 miles from
the city designed to halt their advance. That happened in 2010.
While federal officials contend the electric barrier and other measures to
protect the Great Lakes from Asian carp are working well, critics say
they’re inadequate. Several independent studies have called for permanently
separating the lakes from the carp-infested Mississippi River basin by
putting structures in the Chicago waterways.
That’s the course sought in a federal lawsuit filed by five states —
Michigan, Wisconsin, Minnesota, Ohio and Pennsylvania — and the Grand
Traverse Band of Ottawa and Chippewa Indians in Michigan.
Michigan Attorney General Bill Schuette said Tuesday that the recent eDNA
discoveries were further incentive to continue the lawsuit. More than 80
positive samples have been recorded this year, he said.
Federal attorneys have asked U.S. District Judge John Tharp Jr. to dismiss
the lawsuit, noting that Congress passed a law this year ordering the Army
Corps of Engineers to complete a study by January 2014 of how to close
pathways for invasive species between the Great Lakes and the Mississippi
The Corps said this month it will release a report with options by the end
of next year but will need more study to select the best one.
“Asian carp are knocking at the front door of the Great Lakes, and we cannot
afford to wait on a federal government that fails to act,” Schuette said.