ST. PAUL (AP) — The state Department of Natural Resources has confirmed the presence of zebra mussel larvae in Red Lake in northern Minnesota.

The DNR announced the finding Monday after studying samples gathered last summer by biologists from the Red Lake Nation.

Zebra mussel larvae typically indicate the presence of a reproducing population of zebra mussels. No adult zebra mussels have been identified, but DNR research scientist Gary Montz says "the most reasonable conclusion" is that the larvae came from adult reproduction within the lake.

Montz says since Red Lake is large and shallow, it's impossible to estimate how many of the invasive pests may be in Upper Red Lake and where they're distributed from this sample.

Officials from the DNR and Red Lake Nation are working together to determine their next steps.