Using Closed-Captures Population Analyses to Estimate Channel Catfish Relative Abundance

Channel catfish (Ictalurus punctatus) is an important recreational species in the Great Plains, and understanding the reliability of population data is critical to proper management. We therefore compared estimates of the abundance of channel catfish > 200 mm within a 6.2 river kilometer (RKM) reach of the Missouri River, Nebraska, using estimates derived from the Schnabel batch-marking methodology, closed-captures analyses using capture histories of uniquely marked individuals, and a method for extrapolating relative abundance (C/f) to absolute abundance using mean capture probabilities. Estimated abundance of channel catfish derived using the Schnabel method was 23,949 fish (18,011–39,120; 95% confidence interval). Closed-captures analyses yielded an estimated abundance of 25,817 channel catfish (24,885–26,785; 95% confidence interval). The estimated abundance of channel catfish extrapolated from C/f was 26,121 (24,755–28,056; 95% confidence interval). The smaller confidence intervals around estimates derived using uniquely marked individuals suggest the closed-captures method may result in more robust estimates than those derived using batch-marking techniques or C/f. However, all three methods produced similar estimates of channel catfish abundance. Our results confirm the hypothesis that C/f is proportional to abundance in this study, suggesting an index of relative abundance may be useful when sampling resources are limited.