MADISON (WKOW) -- Dane County says it will work with the UW and the DNR to address the discovery of spiny water fleas in area lakes.
Last week, the University of Wisconsin announced the discovery of spiny water fleas in Lake Mendota. Undergraduates in Dr. Jake Vander Zanden's limnology class discovered the invasive species when they collected water samples from University Bay. Since then, spiny water fleas have been confirmed in Lakes Monona and Waubesa. Those confirmations were made using water samples taken from the lakes in August and September by the UW Center for Limnology.
Spiny water fleas are tiny predatory crustaceans that threaten aquatic ecosystems and fishing by competing with native fish for food. Unfortunately, right now there is no effective strategy to control spiny water fleas once they are introduced to lakes.
"We have worked proactively over the years to prevent harm to our aquatic ecosystems by keeping invasive species out of our lakes and streams. The long-term impacts of the newly-discovered water flea are unknown at this time, but we need to take all steps necessary to prevent their spread to other waters," said Dane County Watershed Management Coordinator Sue Jones.
"Their long-term effects can be significant depending on how well the spiny water fleas establish themselves, and must be taken seriously," said Ron Martin, lead author of Dane County's Aquatic Invasive Species Prevention and Control Plan. "In other lakes they have reduced the abundance of zooplankton (tiny aquatic animals eaten by fish), and that's not good for fish or for water quality."
The invasive species was first discovered in Lake Ontario in 1982. Since then, the spiny water flea has spread to all of the Great Lakes, inland lakes, and most recently lakes Mendota, Monona, and Waubesa. The invasive specie travels to new lakes on fishing gear and in or on boats or other vessels that are transferred from contaminated waters. The fleas collect in masses on fishing lines and downrigger cables. The masses can clog the eyelets of fishing rods and damage a reel's drag system, which can prevent fish from being landed.
Dane County will promote its AIS Plan and the Plan's recommended actions as a way to prevent the transport and introduction of all aquatic invasive species like spiny water fleas.
Those actions include:
- inspect boats, trailers and equipment and remove aquatic plants, animals and mud. Spiny water fleas are small (1/4-5/8 inches total length) and although visible to the naked eye, are difficult to identify without magnification. They appear as gelatinous or cotton batting-like material with black dots on fishing lines, especially where they meet a swivel, lure or downrigger ball connection.
- drain water from boats and all equipment
- don't move live fish away from a waterbody
- buy minnows from a Wisconsin bait dealer. Use leftover minnows only under certain conditions
rinse boats and equipment with hot or high-pressure water or dry for at least 5 days
Dane County staff will add decals indicating the presence of the spiny water fleas to all aquatic invasive species signs posted on lakes Mendota, Monona, and Waubesa.
Dane County staff will also work with the DNR and the UW Center for Limnology to assess the impact the spiny water flea is having on Lake Mendota and downstream lakes in the Yahara River chain, and the extent of the fleas' infestation.
County staff will also continue to encourage riparian owners to track the spread of aquatic invasive species by examining their piers and boats for zebra and Quagga mussels, as well as spiny water fleas, when they remove equipment from the water this fall. While large adult zebra or Quagga mussels are easy to identify, smaller mussels that have recently attached to piers or boats will feel like rough sandpaper and can be much harder to identify.
If you think you have spotted an invasive species animal, please write down the exact location, store a specimen in rubbing alcohol in a sealed container and call the DNR at (608) 275-3329.
For a Spiny Water Flea fact sheet, click here.
For more information on identifying water fleas, click here.