News from WTIP: Zebra mussels found in Pike Lake near Duluth

Submitted by wtip on Thu, 07/02/2009 - 3:45pm

Zebra mussels have been found in Pike Lake. Not the one near Grand Marais -- the one outside Duluth. This is the first confirmed outbreak in a Northeastern Minnesota waterway outside Lake Superior.

The mussels were reported by a local scuba diver and have been confirmed by Doug Jensen, Minnesota Sea Grant aquatic nuisance species expert.
The finding comes 20 years after zebra mussels first were confirmed in the Duluth-Superior harbor. While the mussels can’t move far on their own they’re often spread unwittingly by boaters and anglers when the thumbnail size critters hitchhike in bait buckets, on boats and other gear.

Jensen said it’s surprising that they hadn’t spread earlier to an inland lake up north. He said it’s an indication that actions by boaters and anglers have helped slow the spread. It appears the mussels have been in the lake for at least two years and the infestation is in its early stages.

“There’s no tool in the toolbox to get them out of there at this point,’’ Jensen said, adding that extra efforts now are needed to keep the Pike Lake mussels from moving in boats or bait buckets to other nearby lakes.

Female zebra mussels can produce 100,000 to 500,000 eggs per year. These develop into microscopic, free-living larvae that begin to form shells. It is the only freshwater mussel that can attach to objects.
 
Zebra mussels can cause problems for lakeshore residents and recreationists. Homeowners that take lake water to water lawns can have their intakes clogged. Mussels may attach to motors and possibly clog cooling water areas. Shells can cause cuts and scrapes and anglers can lose tackle as the shells cut fishing line.

In the late summer or fall when you remove equipment from lakes or rivers inspect hard surfaces for zebra mussels -- docks, dock floats and supports, swimming platforms, boats, motors, anchors, and any objects that have been in the lake or river for the summer. Check areas where zebra mussels may be attached, such as trim tabs, rubber gaskets, grooves along the keel of pontoon boats, and sailboat centerboards.

Cook County summer residents and cabin visitors can keep tabs on any local infestation by making a monitoring device. Hang a PVC pipe, brick or cinder block under a shady spot on your dock this summer to monitor for zebra mussels. Suspend the object as deep as possible at the end of your dock, keeping it at least one foot above the bottom. Add your observations to the Volunteer Monitor Report Form, available from the DNR.