LOWER RED LAKE (AP) -- Red Lake Nation tribal scientists are checking the waters of Lower Red Lake frequently for the appearance of zebra mussels that have already invaded the Upper Red.

They're worried that the destructive creatures will spread quickly and threaten a fishery that produces 1 million pounds of walleye per year.

And some Red Lakers see the problem as a failure by people outside the reservation to keep zebra mussels out. The young zebra mussels came in via boats used by non-tribal members accessing the eastern part of Upper Red _ which the tribe doesn't control.

Tribal secretary Sam Strong says there weren't enough invasive species inspectors on Upper Red Lake to guard against infected boats.