A National Park Service biologist says testing by an Indiana lab has confirmed that invasive silver carp have swum up the Mississippi River as far as Lock and Dam No. 1.
Byron Karns said in an email to MPR News that samples taken from the waters downstream from the dam, which sits in between St. Paul's Highland Park neighborhood and Minneapolis' Minnehaha neighborhood, tested positive for the presence of silver carp DNA.
Crews from the park service, the Department of Natural Resources and the U.S. Fish and Wildlife Service gathered water samples near the lock and dam in late September.
Tests in the same area earlier this year didn't indicate the fish may be present.
"But the water was high and full of sediment, so that hindered detection. But now with the water low, this really didn't surprise us," said Paul Labovitz, superintendent of the Mississippi National River and Recreation Area. "It's disappointing to confirm, but its not a surprise."
Labovitz' organization helped conduct the DNA tests and said the next step it to confirm the DNA evidence by capturing a live fish. The DNR says its hiring a commercial fishing contractor to do that.
Labovitz also said that one of the samples that tested positive was inside the mouth of the Minnesota River. That could mean more than 300 additional miles of Minnesota waterway is at risk of being taken over by the fast-growing fish.
More results are expected from samples even further upstream, including the Mississippi River above the Coon Rapids dam.
So far, no silver carp have been found upstream from Lake Pepin.
But David Lodge, the Notre Dame biology professor who discovered the DNA sleuthing process for finding carp, said he's pretty sure that will happen. Lodge said it's the same well-known technology used by crime labs and it has been checked against waters where the fish have been found.
"It is indeed a more sensitive tool than the traditional tools of trying to figure out whether a fish is there or not, and by traditional tools, I mean netting and electrofishing," he said.
The invasive fish been known to all but take over waterways as they have made their way up the Mississippi River.
John Anfinson, with the National Park Service, told MPR News in September that the presence of the fish is all too apparent down the Mississippi River. He saw for himself when the Army Corps of Engineers lowered a river pool near St. Louis.
"When the river dropped there in the backwaters, the beaches were lined with a 10-foot-wide window of dead Asian carp," Anfinson said.
POLITICAL BATTLE BREWING
Actually finding the fish could touch off a legal and political battle. The Ford Dam has a unique construction that would make it one of the only existing barriers to the fish on the Mississippi. But that would require closing its locks to shipping — forever.
The risk is that fish could potentially spread like other invasive species and damage the state's $1.6 billion sport fishing industry.
But shipping is also a multi-million dollar industry that depends in part on the Mississippi River in the Twin Cities.
Bob Bieraugel, manager of properties and environmental services for Aggregate Industries, said his company ships gravel, stone and sand upriver from Grey Cloud Island. He said it would take 20,000 trucks to move the 400,500 tons of freight they move per year.
Bieraugel questions whether drivers would want to share the road with the traffic it would take to replace the barges.
Shippers also cite a study by the trade group American Waterways. It said in 2005 that barges produce about a quarter of the greenhouse gasses of trucks for comparable loads.
Aggregate and Minneapolis recycler Northern Metals say that between them, they have more than 100 jobs that depend on navigating the Mississippi.
And now it looks likelier than ever that Minnesota will have to weigh that dilemma.