Date of this Version
The Prairie Naturalist 51:17-24; 2019
Electrofishing is commonly used by fisheries professionals to assess fish assemblage structure and species abundance in streams. Accurate estimates of fish abundance and, consequently assemblage metrics, are typically generated with mark-recapture or maximum-likelihood depletion techniques, but doing so requires considerable sampling effort. Less intensive sampling approaches may be beneficial to fisheries managers, particularly in cases where frequent sampling of many streams is preferred. We used regression and Spearman rank-order correlation analyses to compare species catch rates and the assemblage metrics generated from single-pass electrofishing samples with multiple-pass depletion abundance estimates in Nebraska streams. We examined the influence of instream habitat features on the regression residuals to further examine the effectiveness of single-pass electrofishing. Our results suggest that single-pass electrofishing is suitable for wadeable prairie streams with relatively little habitat diversity. With few exceptions, fish species were detected and captured in similar quantities regardless of electrofishing effort, suggesting that single-pass sampling can be used to quickly assess species occurrence and relative abundance. The single- and multiple-pass electrofishing methods generated slightly different values for each assemblage metric; however, these values were not significantly different. Abundance was over- or underestimated in areas where certain species were congregated (e.g., overhanging vegetation: Red Shiner Cyprinella lutrensis, Bigmouth Shiner Notropis dorsalis, large substrates: Stonecat Noturus flavus, and darters) or difficult to sample (e.g., woody debris: Largemouth Bass Micropterus salmoides and Western Mosquitofish Gambusia affinis) using only one electrofishing pass. Single-pass electrofishing offers a reliable alternative to the more intensive multiple-pass depletion techniques; however, caution should be applied in difficult to sample areas with unique habitats.