Contribution of Hatchery‐Reared Walleyes to Populations in Northern Green Bay, Lake Michigan

The effectiveness of stocking hatchery‐reared Walleyes Sander vitreus to supplement native populations in large, open systems like the Great Lakes has not been thoroughly evaluated. I quantified recent contributions of stocked Walleye fingerlings to populations in Little Bay de Noc (LBDN) and Big Bay de Noc (BBDN) in northern Green Bay, Lake Michigan. Oxytetracycline‐marked Walleye fingerlings were stocked in June, and late summer gill‐net and night‐time boat electrofishing surveys were used to index Walleye year‐class abundance and collect juvenile Walleyes for hatchery mark evaluation. For the 2004–2009 year‐classes, 76% of the age‐0 to age‐3 Walleyes examined from LBDN were of wild origin and 62% in BBDN were naturally reproduced fish. Survey catch rates of juvenile Walleyes were similar for stocked and nonstocked year‐classes. Assessment catch rates of age‐1 and age‐2 Walleyes differed significantly by location, with average catch rates in LBDN often being ten times higher than those in BBDN. Age‐0 Walleyes persisted to older ages and were well‐represented at numerous sampling locations in LBDN, but few age‐1 and older Walleyes were caught in BBDN. The differences in growth between hatchery‐reared and wild Walleyes were minor compared with the differences between bays. Based on stocking records and creel estimates available since 1985, the harvest rate of Walleyes was not significantly correlated to the numbers of Walleyes stocked 4–6 years earlier in LBDN or BBDN. Despite low stocking rates, stocked fish likely provided some contribution (though not a statistically significant one) to Walleye year‐classes and the sport fishery in LBDN, but their contribution in BBDN was less apparent. Managers should weigh the trade‐offs of supplemental stocking in Great Lakes waters when considering requests for hatchery Walleyes in smaller lakes and rivers, especially when stocking resources are limited.