Seasonal Food Habits and Prey Selectivity of Alligator Gar from Texoma Reservoir, Oklahoma

Alligator gar (Atractosteus spatula) were once viewed negatively by anglers and state agencies, but interest in reintroduction and trophy management of gar has increased in many states across their range, including Oklahoma. Therefore, the Oklahoma Department of Wildlife Conservation is planning to reintroduce alligator gar back into their native range. Thus, biologists decided to implement a food habits study to determine potential impacts of alligator gar to other fish populations in order to address angler concerns about possible reintroduction. The objectives of this study were to describe seasonal food habits and prey selection of alligator gar collected from Texoma Reservoir located on the Texas-Oklahoma border. Fish were mostly collected using gill nets but 36% were also donated by anglers. Diets were pooled into two seasonal groupings (winter-spring and summer-fall). Stomach contents were analyzed from a sample of 138 alligator gar (56 in winter-spring; 82 in summer-fall). Alligator gar were primarily piscivorous, with gizzard shad being the predominant prey item consumed across seasons. Although alligator gar primarily consumed nongame fish, striped bass (Morone saxatilis) occurred in 11% of diets with other sportfish representing a combined occurrence <4%. Prey selectivity was evaluated using a jug-line survey during summer 2017 and 2018. Each jug line was baited with a dead whole fish from one of six prey taxon (three sportfish: catfish [Ictalurus spp.], largemouth bass [Micropterus salmoides], and white crappie [Pomoxis annularis]), and three nongame species: buffalo [Ictiobus spp.], gizzard shad [Dorosoma cepedianum], and river carpsucker [Carpiodes carpio]). Of the 101 alligator gar caught with juglines, buffalo and river carpsucker were the only two prey items with positive selectivity values. Alligator gar selected neutrally for gizzard shad and selected against catfish, largemouth bass, and white crappie. This study provides fisheries managers with important information regarding alligator gar diets and prey selection, which can be valuable when addressing angler concerns about future reintroduction efforts.

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