Researchers analyzed water samples for DNA fragments released to the environment, called eDNA. They found silver carp eDNA in Iowa, where the fish are abundant, but none near St.

WSJ: Study finds Asian carp numbers low in Minnesota

Croix rivers found little evidence of bighead and silver carp, according to a study released Thursday that concludes that while the invasive fish are present in Minnesota, their numbers are likely relatively low.

WSJ: Study finds Asian carp numbers low in Minnesota

In eDNA testing of samples taken in 2011, a year earlier, researchers recorded a positive eDNA test of silver carp above the Coon Rapids dam on the Mississippi River, raising alarm that the fish were heading upstream faster than anticipated.

WSJ: Study finds Asian carp numbers low in Minnesota

Of particular concern are silver and bighead carp, which gorge on plankton microscopic plants and animals that virtually all fish eat at some point.

WSJ: Report: Asian carp may have reached Great Lakes