Asian carp are in the Mississippi along Fridley's riverfront.

That's the word Thursday from the Minnesota Department of Natural Resources in a surprise announcement that said samples taken around the Coon Rapids Dam were positive for Asian carp DNA.

No one has seen the dreaded invasive fish in the area yet, and there is a chance that the DNA got into the dam area some other way.

But the tests suggest that the Coon Rapids Dam, seen as a potential barrier to the carp's migration, has already been breached.

Scientists sampled the river in 48 locations around the dam in September. Of 29 samples below the dam, 16 tested positive for silver carp, known for leaping out of the water as they migrate upstream.

Even more alarming: Three of the 19 samples taken above the dam tested positive.

Silver carp eat huge quantities of algae and other organisms, leaving little for native fish, according to the DNR. They could quickly upset ecosystems in the Mississippi River and its tributaries.

Gov. Dayton has set a third Asian Carp Summit meeting for Dec. 20. At a Carp Summit in October, experts said the Coon Rapids Dam could function as a backup fish barrier to the locks and dams at St. Anthony Falls in Minneapolis. But seasonal ice jams at Coon Rapids likely will change water levels enough to make it possible for the jumping carp to get past the dam.

Tim Schlagenhaft, Mississippi River manager for the DNR, said in an interview Thursday that there could be explanations other than migration for the presence of DNA from Asian carp mucous and excrement. Birds or boats could be transporting the fish, Schlagenhaft said.

"It's not likely but we need to rule them out," he said.

But positive tests upstream from the Coon Rapids dam suggests that positive tests downstream will continue. "DNA would be drifting down," Schlagenhaft said.