Iowa's DNR Hopes For Results with New Approach to Controlling Gizzard Shad

The Iowa Department of Natural Resources will try a new approach to rid Lake Sugema of gizzard shad later this fall.

Mark Flammang, fisheries biologist for the Iowa DNR, said the plan is to apply Rotenone, a chemical toxic to fish, at 3 percent of the normal dosage in a slow, deliberate manner to create a drawn out fish kill targeting gizzard shad and sparing as many game fish as possible.

"Gizzard shad are highly susceptible to Rotenone," Flammang said. "We are walking a tightrope but we feel confident we can be successful with only minimal loss of game fish."

The low-dose application method has worked in other states and was successful in a trial run at the 12-acre Old Reservoir at Mt. Ayr. Lake Sugema is 574 acres.

Lake Sugema provides excellent fishing for largemouth bass, bluegill, walleye, muskie, crappies and channel catfish for southeast Iowa.

"Sugema is such a high quality fishery that we need to try everything in our power as soon as we can to eliminate the gizzard shad," Flammang said.

The alternative is to eliminate the entire fish population and start over, which would take considerable time. Fishing would decline each year and fewer anglers would make the trip to Sugema. "That is an unacceptable first response," he said.

Flammang said the Sugema plan will be to lower the water level a few feet to create some storage capacity in the case of rain, close the outlet, then during the week of November 15, to slowly apply 200 gallons of Rotenone. He said there will not likely be any dead fish visible during the actual day or up to a few weeks following the application.

"At this application rate and water temperature, the chemical should continue to kill shad for quite a while," Flammang said.

He will return in the spring to see if they were successful.

It is illegal to stock fish in any public water of the state, including game fish. The public is asked to report any of this illegal activity to their local conservation officer or by calling the Turn-in-Poachers (TIP) hotline 1-800-532-2020. Callers can remain anonymous.