The Minnesota Department of Natural Resources says genetic evidence of silver carp has been found above the Coon Rapids dam, raising new questions about whether the state can still stop the advance of the invasive fish.
Tim Schlagenhaft, Mississippi River manager for the DNR, announced the results this morning at an Asian Carp task force meeting at the Minnesota Valley Wildlife Refuge Visitor Center in Bloomington.
He said environmental DNA tests taken showed evidence of the leaping silver carp above and below the dam on the Mississippi just north of the Twin Cities. He said three of 19 samples tested positive above the dam and 16 of 29 below it.
The highly sensitive tests are designed to detect DNA in the environment that comes from the mucus or excrement of invasive Asian carp.
Schlagenhaft said that evidence is not conclusive proof those fish have gotten that far upstream – that other sources, such as a discarded carcass, could be responsible.
“This is surprising because we felt like Coon Rapids was a pretty good fish barrier, but…it doesn’t tell us for certain there is a live fish,” Schlagenhaft said.
“We also believe that the risk of these fish getting upstream is too high to not assume that there’s live fish above there…or information tells us that the DNA is coming from another source,” Schlagenhaft said.
Earlier results showed evidence of the fish below the Ford dam in the Twin Cities.
Peter Sorensen, a University of Minnesota scientist and Asian carp expert, said the evidence tells him the fish have gotten that far.
“It is extremely unlikely, almost impossible to imagine, that the DNA in the waters is coming from anything other than silver carp,” Sorensen said.
The DNR is still waiting for results from the Minnesota River, more from the St. Croix River, including above a dam in St. Croix Falls, and below the St. Anthony lock and dam in Minneapolis.
Asian carp are an invasive type of fish that have been making their way up the Mississippi River toward Minnesota for years.
So far, most of the eDNA tests done on Twin Cities metro area rivers have come back positive for silver carp, but extensive netting efforts in the St. Croix and other parts of the Mississippi River this summer and fall have not yielded any of the elusive fish.
The netting results and ongoing commercial fishing in the Mississippi River further downstream suggest a very low population of invasive carp, said Schlagenhaft, so there is still time to implement strategies to slow their movements and keep population levels low.
Gov. Mark Dayton will hold his third Asian Carp summit Dec. 20 to discuss the state’s proposed actions on Asian carp.
Dennis Lien can be reached at 651-228-5588.