A Comparison of Walleye Fry and Fingerling Stockings in Three Rivers in Iowa

Abstract

Ranking third in angler preference, walleye Stizostedion vitreum is one of the most important sport fish in Iowa, yet this species is rare in inland rivers. From 1986 through 1989, fry and fingerling walleyes were marked with coded wire tags and freeze brands, stocked in three Iowa rivers, sampled by seining, and electrophoretically analyzed to evaluate their survival 2–3 weeks after stocking. Two river strains and one lake strain of walleyes were stocked. Fall electroshocking provided annual survival and population estimates. No significant contribution resulted from stocked walleye fry; however, stocked fingerlings averaged 76% of young-of-year walleyes for each study reach, and they averaged more than 50% of the total populations. Actual fingerling contributions were 95–100%, but extensive tag loss prevented conclusive identification. Fingerling walleye growth was excellent initially, exceeding 20 cm the first year, but it decreased the following years under drought conditions and high population densities. Minimum estimates of annual survival for walleyes stocked as fingerlings (young of the year to age 1) ranged from <1 to 16%; these estimates did not incorporate substantial movement and tag loss. Standing stocks of Cedar River walleyes improved from <1 to 17 kg/hectare. Fingerling walleye stockings improved all river populations substantially, but fry stockings were inconsequential and should be discontinued.