The Iowa Department of Natural Resources (DNR) has confirmed that a zebra mussel was recently found in Lake Cornelia. Further investigation revealed no additional adult zebra mussels, but veligers, which are the larval stage of zebra mussels, were found in a water sample.
DNR staff will continue to monitor Lake Cornelia this summer to determine whether there is an established population of zebra mussels.
Zebra mussels look like small, D-shaped clams that have alternating light and dark bands. Most are less than one inch long.
Zebra mussels are native to the Caspian Sea region of Asia and were introduced into the Great Lakes in the 1980s from ballast water of oceangoing ships. They have spread throughout lakes and rivers in the Midwest and around the country. Known populations within Iowa include Clear Lake, Bluebill Lake, the Okoboji chain of lakes, and the Mississippi River.
Zebra mussels are filter feeders that can form dense clusters as they attach to hard underwater surfaces. In the case of large infestations, they may interfere with aquatic food chains, kill native mussels, clog water intakes, increase algae blooms, and cover beaches with dead shells. Currently there is no effective treatment to control zebra mussels once they have infested a lake.
Documenting zebra mussels in another lake highlights the spread of aquatic invasive species in Iowa waters. The zebra mussels in Lake Cornelia probably arrived on or in a boat that had picked up the mussels from an infested water body.
Zebra mussel veligers are microscopic and can be unintentionally transported with water in live wells, bilges, or bait buckets. Adult zebra mussels can attach to boats, trailers, and aquatic vegetation.
It is illegal to possess or transport prohibited aquatic invasive species, such as zebra mussels, in Iowa. Boaters must also drain all water from boats and equipment before leaving a water access and must keep drain plugs removed or opened during transport.
“Draining all water is a critical step in preventing the spread of zebra mussels,” said Kim Bogenschutz, the DNR’s aquatic invasive species program coordinator. “Boaters and anglers need to – clean, drain, dry – after each time out on the water to prevent the spread of all aquatic invasive species.”
- CLEAN any plants, animals or mud from boat and equipment before leaving a water body.
- DRAIN water from all equipment (motor, live well, bilge, transom well, bait bucket) before leaving a water body.
- DRY anything that comes into contact with water (boats, trailers, equipment, boots, clothing, dogs). Before transporting to another waterbody either:
- Spray your boat and trailer with hot, high-pressure water; or
- Dry your boat and equipment for at least 5 days.
- Never release plants, fish or animals into a water body unless they came out of that water body and empty unwanted bait in the trash.
More information about aquatic invasive species and a list of infested waters can be found in the 2014 Iowa Fishing Regulations booklet.
The DNR is requesting the help of anglers, boaters, and homeowners in the search for zebra mussels in Lake Cornelia. If you see a zebra mussel, please note its location and contact Wright County Conservation Board staff or the Clear Lake Fisheries Office at 641-357-3517.