Your help is needed! We need to monitor our lake for zebra mussels. Become a Zebra Mussel Volunteer monitor!
How can you monitor for zebra mussels? In the late summer or fall when removing equipment from lakes or rivers:
1. Visually inspect hard surfaces for zebra mussels such as 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. During early infestations, zebra mussels are likely to be small (1/4-1/2 inch long) and the number attached on any object is likely to be low. You can also examine rocks and other hard surfaces along the shoreline and in shallow water, especially near water accesses.
2. Complete and send in an online volunteer monitoring form by November 1st each year. Send in the report whether or not you found zebra mussels.
3. Make your own monitoring device. Hang a PVC pipe , brick or cinder block under a shady spot of your dock (zebra mussels tend to avoid direct sunlight) in the 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. Examine the monitoring object, and add these observations to the Volunteer Monitor Report Form.
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General Characteristics
- Zebra mussels look like small clams with a yellowish or brownish “D”-shaped shell, usually with dark and light-colored stripes (hence the name “zebra”)
- They can be up to two inches long, but most are under one inch. Zebra mussels usually grow in clusters containing numerous individuals and are generally found in shallow (6-30 feet), algae-rich water
- Zebra mussels are the only freshwater mollusc that can firmly attach itself to solid objects – submerged rocks, dock pilings, boat hulls, water intake pipes, etc.
- On smooth surfaces, young zebra mussels feel like fine sandpaper.
- Juveniles are about the size of peppercorns.
Impacts: Zebra mussels can cause problems for lakeshore residents and recreationists. Mussels may attach to motors and possibly clog cooling water areas. Shells can cause cuts and scrapes if they grow large enough on rocks, swim rafts and ladders. Anglers may lose tackle as the shells can cut fishing line. Homeowners that take lake water to water lawns can have their intakes clogged. Zebra mussels can also attach to native mussels, killing them. Zebra mussels filter plankton from the surrounding water. If a lake has high numbers of mussels over large areas, this filter feeding could impact the food chain, reducing food for larval fish.
Status: They have spread throughout the Great Lakes and the Mississippi River from Brainerd downstream, and are now in other rivers and inland lakes. They are established in Minnesota and were first found in the Duluth/Superior Harbor in 1989. Some popular Minnesota lakes currently infested with zebra mussels include: Minnetonka, Pelican, Le Homme Dieu, Fish Lake, Prior lake, Gull lake and Mill Lacs. The Infested Waters list provides details of current infestations. Diving ducks, freshwater drum (sheepshead), and other fish eat zebra mussels, but will not significantly control them.
Means of spread: Mussels attach to boats, nets, docks, swim platforms, boat lifts, and can be moved on any of these objects. They also can attach to aquatic plants, making it critical to remove all aquatic vegetation before leaving a lake. Microscopic larvae may be carried in water contained in bait buckets, bilges or any other water moved from an infested lake or river.
What You Can Do
- Learn to recognize zebra mussels.
- Inspect and remove aquatic plants, animals, and mud from boat, motor, and trailer.
- Drain water from boat, motor, livewell, bilge, and bait containers.
- Dispose of unwanted live bait and worms in the trash.
- Rinse boat and equipment with high-pressure and/or hot water (104° F), especially if moored for over a day, OR
- Dry everything for at least 5 days.
- Never introduce fish, plants, crayfish, snails or clams from one body of water to another.
- Report new sightings - note exact location; place specimens in a sealed plastic bag or store in rubbing (isopropyl) alcohol; if in Minnesota, call the Minnesota Sea Grant Program in Duluth, (218) 726-8712; the Minnesota DNR in St. Paul, 1-888-MINNDNR, or (651) 259-5100; or a local DNR fishery office.
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