Based on preliminary sampling, the effort to eliminate gizzard shad from Lake Sugema, one of southeast Iowa's most popular lakes, appears to have worked.
Last November, the Iowa DNR lowered the lake level and fisheries staff applied the fish toxicant, Rotenone, 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.
Unfortunately, it appears that it may have also have negatively impacted the walleye population, a prized species in this 574-acre lake.
"We would much prefer to have left this outstanding resource as it were, supporting high-quality fishing for all species present; however, the misguided and illegal introduction of gizzard shad to this system sealed the fate of these fish," said local fisheries biologist, Mark Flammang.
"Had we not moved to eliminate gizzard shad, we would have eventually lost the entire fishery. If we find that we successfully eliminated shad then our mission was accomplished. The negative impacts to the walleye population are unfortunate collateral damage of an illegal act," Flammang said.
Spring sampling of the lake has found no trace of gizzard shad and while that is a sign for optimism, Flammang said intensive sampling will continue through 2011. If they have not collected a single gizzard shad by late summer, he would then declare the lake shad-free.
Flammang has requested 10-inch walleye fingerlings that will be stocked in the lake in October, if the lake remains shad free.
"It is certainly unfortunate that walleyes exhibited a lower tolerance to rotenone than other game fish. However, the bottom line is excellent populations of largemouth bass, bluegill, and crappie remain, essentially unaffected by the recent shad introduction and subsequent treatment," Flammang said.
"The sad part is, that the walleye fishery was starting to catch on and people were becoming more aware of it," he said. "Even with this setback, Sugema has excellent bass, bluegill and crappie fishing anglers have come to expect."
Iowa law makes it illegal to possess live gizzard shad. It is also 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.