Effectiveness of Continuous versus Point Electrofishing for Fish Assemblage Assessment in Shallow, Turbid Aquatic Habitats

Abstract

We evaluated the relative effectiveness of continuous versus point electrofishing methods for describing fish assemblage metrics in the lower Atchafalaya River Floodway system, Louisiana. Continuous data were collected by boat electrofishing opposing shores of a 100-m reach for a total of 480 s. Point data were collected in an adjacent 100-m reach by boat electrofishing for 60 s at four points (240 s total) at 25-m intervals on alternating shorelines. We tested for significant differences between the methods with a linear model for species richness and CPUE (fish/min) and a generalized linear model for species diversity. We also compared the length frequencies of Largemouth Bass Micropterus salmoides between methods. We found no difference in diversity between methods but significantly higher species richness (mean = 1.46 species) and significantly lower CPUE (mean = –24.63 fish/min) for continuous electrofishing. We found no difference in Largemouth Bass length frequency between methods, but point electrofishing captured more individuals between 300 and 400 mm. Our results indicate that point electrofishing may be an efficient, effective technique for capturing target species and larger individuals that may otherwise avoid capture. When coupled with continuous electrofishing, point electrofishing may bolster assemblage and population size structure data, particularly in shallow, turbid environments.

Received July 9, 2014; accepted December 8, 2015 Published online March 31, 2016

Acknowledgments

We would like to thank M. Baker, J. Beasley, S. Benson, C. Bonvillain, A. Fitzgerald, M. Fries, B. Hartman, Z. Herrington, K. Jefferis, L. Kaczmarowski, R. Leeson, R. Lewis, B. Miller, D. Oliver, A. Piehler, W. Sheftall, J. Vazquez, and A. Williamson for their assistance with data collection. We would also like to thank the U.S. Army Corps of Engineers, New Orleans District, for funding this research and monitoring. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Manuscript content is solely the responsibility of the authors and does not necessarily represent the official views of the U.S. Government. This manuscript was approved for publication by the Director of the Louisiana Agricultural Experiment Station as manuscript 2015-241-22525.