KEOSAUQUA, Iowa – The Iowa Department of Natural Resources (DNR) will treat Lake Sugema on Oct. 29 (pending workable weather conditions) with a very low concentration of rotenone to eliminate gizzard shad. If the treatment is postponed, it will be rescheduled for sometime with better weather conditions this fall.
Lake Sugema will be closed to all recreation on Oct. 29 and will reopen on Oct. 30. The public will not be allowed within the treatment zone while the rotenone is being applied.
This low treatment level, about 4 percent of the normal dosage, allows the DNR to specifically target the shad with few impacts to other game species. Rotenone, a natural pesticide derived from the roots of certain members of the bean family from South America, is a common tool that fisheries managers use to manage sport fish, improve water quality, and manage endangered species.
Anglers should not retrieve dead or dying fish; rotenone label guidelines do not allow for human consumption of treated fish.
Gizzard shad, an injurious species, were illegally introduced to Lake Sugema in 2015. The growing gizzard shad population has reduced game fish abundance and quality, decreased water quality and limited fishing activity for some species.