Comparison of Day and Night Electrofishing in Texas Reservoirs

Abstract

Our study compared catch rate and size structure of largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and gizzard shad Dorosoma cepedianum between day and night electrofishing, evaluated relative precision of day and night electrofishing, and evaluated effects of water transparency on differences in day and night catch rates in the spring and fall for 16 Texas reservoirs. Day and night catch rates of largemouth bass were similar in the spring, but night electrofishing collected significantly more 8.0–14.9-in (total length) largemouth bass in the fall. Night catch rates were significantly higher than day catch rates for bluegills over 2,9 in long in the spring and fall. Catch rates of gizzard shad more than 6.9 in long were significantly higher at night in the spring but were similar for all length categories in the fall. Relative precision of catch rates was generally higher with night electrofishing. Water transparency explained a significant portion of the variation in differences between day and night electrofishing in some instances, but not in others, suggesting that this variable was not the only factor affecting differences between day and night electrofishing catches.