Diet and Population Characteristics of Stocked Age-0 Saugeye in an Oklahoma Reservoir

Fish growth early in life typically affects recruitment to adulthood. For this reason, fisheries managers stock fish of varying sizes (e.g., fingerling or advanced fingerling rather than fry, which are less expensive to produce) hoping that an initial size advantage results in improved survival. Saugeye (Sander vitreus x S. canadensis) are hatchery-produced hybrids that are stocked into many Midwestern and southern U.S. reservoirs to create sportfishing opportunities. A saugeye stocking program was initiated at Arcadia Reservoir, Oklahoma, in 2017 when 38,110 fingerlings were stocked. In 2018, 146,086 fry were stocked into Arcadia Reservoir. This provided us the opportunity to compare differences in diet, growth, and mortality between two year-classes of age-0 saugeye stocked at different sizes. Age-0 saugeye (184 in 2017 [stocked as fingerlings], 198 in 2018 [stocked as fry]) were collected across 14 sampling events during July 2017?May 2019 using boat electrofishing to analyze diets and population characteristics. Gizzard shad (Dorosoma cepedianum) were the most important identifiable prey item found in juvenile saugeye diets for both stocked cohorts, but inland silversides (Menidia beryllina) and centrarchids contributed substantially to age-0 saugeye diets. Mean TL of age-0 saugeye were similar between the two cohorts by late summer. However, saugeye stocked as fingerlings in 2017 were larger than those stocked as fry in 2018 by their first spring. Daily mortality estimates were significantly higher for saugeye stocked as fingerlings in 2017 than fry stocked in 2018. Fisheries managers should stock fingerlings to capitalize on improved growth rates, which allows for creation of recreational saugeye fisheries more rapidly; however, abundance of forage may mediate growth and survival of stocked fish regardless of their size at stocking

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