The Iowa Department of Natural Resources (DNR) recently found zebra mussels on a sampler in Bluebill Lake. The sampler was placed in the lake specifically to monitor for zebra mussels because of the lake’s proximity to Clear Lake, which has had zebra mussels since 2005. Bluebill Lake is a 40-acre lake located 4 miles south of Clear Lake.
“We put zebra mussel samplers in lakes surrounding Clear Lake as an early detection system,” said Scott Grummer, the fisheries management biologist for the Clear Lake District. “Unfortunately, the sampler in Bluebill Lake came up positive for 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 spread from the Great Lakes to the Mississippi River and were first documented in the Mississippi River in Iowa in 1992.
Bluebill Lake is the state’s fourth interior lake confirmed to have zebra mussels. Clear Lake, Lake Delhi, and Rathbun Lake are the others.
Zebra mussels are filter feeders that attach to underwater surfaces using fibers called byssal threads. They can interfere with aquatic food chains, kill native mussels, and clog water intakes. And there’s no getting rid of zebra mussels once they are in a lake or river.
DNR biologists plan to continue monitoring Bluebill Lake to determine the abundance and distribution of zebra mussels. Divers will be used to search underwater surfaces in August.
The DNR has increased its monitoring at Bluebill Lake and posted information at the boat ramp about preventing the spread of zebra mussels.
The documentation of zebra mussels in Bluebill Lake highlights the spread of invasive species in Iowa waters. The zebra mussels in Bluebill Lake probably arrived on or in a boat that had picked up the mussels in an infested water body, likely nearby Clear Lake.
Young zebra mussels are microscopic and can be unintentionally transported with water in bilges, live wells, or bait buckets. Adult zebra mussels can attach to boats, trailers, and aquatic vegetation.
“For boats that are trailered between water bodies, a critical step is to drain the bilge and live wells before leaving a boat ramp to make sure you are not transporting young zebra mussels, ” said Kim Bogenschutz, the DNR’s aquatic invasive species program coordinator.
“Boaters and anglers can unintentionally spread zebra mussels and other aquatic invasive species if they do not take the proper precautions – clean, drain, dry – after each time out on the water.”
- 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) before leaving a water body.
- DRY anything that comes into contact with water (boats, trailers, equipment, boots, clothing, dogs). Before transporting to another water body 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.
It is illegal to possess or transport prohibited aquatic invasive species such as zebra mussels in Iowa. The fine for violating this law is $500. Signs are posted at public accesses to remind boaters to stop aquatic hitchhikers and to identify infested waters. More information about aquatic invasive species and a list of infested waters can be found in the 2012 Iowa Fishing Regulations booklet.