Evaluation of Recruitment Variability Factors and Indexing Techniques for Channel Catfish in Oklahoma

Abstract: Commonly, fisheries management decisions are based on one-time samples, which are generally adequate for assessing key rate functions, such as age and growth, but are of limited value for assessing recruitment. Recruitment variability has not been indexed for channel catfish (Ictalurus punctatus). Further evaluation of practical recruitment indexing methods from single sampling events and identification of potential drivers in recruitment variability could provide biologists with additional information needed for improved management of channel catfish populations. In this study, we assess the feasibility of indexing channel catfish recruitment variability with one-time samples using the recruitment variability index (RVI) and recruitment coefficient of determination (RCD). Then we examine spatial, abiotic, and biotic factors that influence recruitment variability across 15 study reservoirs in Oklahoma. Agreement among quartile range-based recruitment categories between RVI and RCD was 60%. The RVI was positively correlated to the CV in mean CPUE of channel catfish for all reservoirs combined. The strongest predictor of RVI from the candidate model set was longitude and no additional predictors fell within 2 ΔAICc of the longitude model. Based on our results, the RVI has utility as a tool for evaluating multiple channel catfish populations within a region, providing managers with an additional method to prioritize stocking needs or identify candidate reservoirs for habitat improvement efforts (e.g., spawning structure, nursery habitat). This method may also provide insight into the application of improvement efforts through the identification of systems that support self-sustaining populations.