There was a glimmer of good news in the battle against Asian carp this morning when the Minnesota Department of Natural Resources announced results from new DNA analyses of water samples from the Mississippi and St. Croix rivers showed little evidence of bighead and silver carp.
According to a news release from the DNR, the joint effort by scientists from the new Minnesota Aquatic Invasive Species Research Center at the University of Minnesota, U.S. Geological Survey and the DNR concludes that while recent captures of Asian carp by commercial fisheries show the invasive fish are present in Minnesota, their numbers likely still are relatively low.
Using a technique that detects DNA fragments released into the environment, studies in 2011 showed positive results for silver carp eDNA in as many as half the samples collected from the St. Croix and Mississippi rivers. The new study detected the eDNA in Iowa, where the fish remain abundant, but no new positive results in the sampling areas just above and below St. Croix Falls in the St. Croix River or in the sampling areas above and below the Coon Rapids Dam or below Lock and Dam No. 1 in the Mississippi River.
In contrast, tests failed to detect bighead carp eDNA at any location, including Iowa, where the fish are known to be present.
“These results support the conclusion that bighead and silver carp have not yet become established in Minnesota,” said Steve Hirsch, director of the DNR’s Ecological and Waters Division. “The threat of Asian carp is nevertheless an urgent issue for the state, requiring immediate action.”
The full report is available at dnr.state.mn.us/asian-carp/index.html under “plans and studies.”