Evaluating the Coarse-Scale Effects of Walleye and Saugeye Stocking on White Crappie Growth in Oklahoma Using Long-Term Data

Abstract

The white crappie (Pomoxis annularis) is an important U.S. game fish but is prone to stunting. In Oklahoma, stocking saugeye (Sander vitreus × S. canadensis) is a common management strategy for improving white crappie growth. However, recent work has suggested that saugeye stocking may not be a broadly effective management tool for improving crappie growth rates, especially when controlling for among­-reservoir variation. Therefore, our objectives were to: (1) determine if stocking of Sander spp. (walleye [S. vitreus], saugeye, or both) improved white crappie growth trajectories along with predicted and observed length­-at­age, and (2) determine if predicted and observed length­at­age yielded similar results to evaluate the potential applicability of using predicted values when observed values are unavailable. We used linear mixed­effects modeling of long­term management data (1984–2020) to determine if metrics associated with stockings of Sander spp. influenced white crappie growth parameters and observed or predicted mean total length (TL) at ages 2 and 3. Stocking of saugeye alone or in combination with walleye did not appear to influence white crappie growth across our sample reservoirs. Stocking of walleye was associated with larger asymptotic maximum sizes and annual walleye stocking rate was positively associated with observed and predicted mean TL of white crappie at ages 2 and 3. The same top model was obtained from candidate sets when using observed and predicted mean TLs, suggesting that model-­predicted values be used in analyses when missing age classes are present. Despite finding a relationship between crappie growth metrics and walleye stocking variables, our random effect (reservoir) explained at least half the variation for all models. This suggests that though walleye stocking may be a promising management tool for white crappie, further evaluation of reservoir­-specific variables that influence its effectiveness is needed.