ST. PAUL, MN (KDAL) - While the growing invasion of Asian carp into Minnesota waterways remains a threat, a study released Thursday by the Minnesota Department of Natural Resources shows that the two species (silver carp and bighead carp) have not yet become established here. The presence of the fish in southern Minnesota riverways is clearly documented, but the report shows little DNA evidence in water samples. The new study consistently detected silver carp DNA in Iowa, where the fish are abundant, but detected none in sampling areas in the St. Croix River, nor near the Coon Rapids dam and Lock and Dam 1 in the Mississippi River. And no bighead carp was detected in either Iowa or Minnesota. That's in contrast to a 2011 study that detected silver carp DNA in about half of samples in Minnesota. Researchers said that difference might be due to technology, the latest of which might have a harder time detecting the DNA in open water. The DNR worked with scientists from the Minnesota Aquatic Invasive Species Research Center at the University of Minnesota and the U.S. Geological Survey.