Day Versus Night Electrofishing Catches from Near-Shore Waters of the Ohio and Muskingum Rivers
Creators:Sanders, Randall E.
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Citation:The Ohio Journal of Science. v92, n3 (June, 1992), 51-59
Day and night electrofishing catches were compared for sampling effectiveness and diel movements offish to and from near-shore waters of the Ohio and Muskingum rivers. Standardized methods were used to collect same-day paired samples by sampling during the day, displacing the catch, and resampling after twilight. Night catches contained significantly higher numbers of species, individuals (excluding Dorosoma cepedianum), weight, and biological index scores (Modified Index of Well-Being [Mlwb] and Index of Biotic Integrity [IBI]). Night versus day paired samples in the Ohio and Muskingum rivers showed, respectively, mean increases of 7.6 and 4.6 species, 229 and 417 fish per km (excluding D. cepedianum), 18.2 and 30.4 kg/km, 2.3 and 1.5 Mlwb units, and 10.8 and 8.7 IBI units. Total night catches yielded, respectively, 43% and 15% more taxa, 62% and 160% greater numbers (excluding!), cepedianum), and 50% and 70% more weight than total day catches. Catch differences were primarily attributed to diel movements from off-shore to near-shore waters during the evening-twilight period. Taxa which increased the most at night in the Ohio River were: Alosa chrysochloris, Notropis wicklijfi, Ictiobus bubalus, Moxostoma anisurum, M. duquesnei, Ictalurus punctatus, Morone saxatilis x M. chrysops, Ambloplites rupestris, Stizostedion canadense, and Aplodinotus grunniens; and in the Muskingum River: Ictiobus bubalus, Moxostoma anisurum, and Morone chrysops. Standardized night electrofishing is an effective sampling technique for many mainstem species and provides a better, more complete biological assessment than day electrofishing. Therefore, it should be incorporated into long-term monitoring programs for these large, deep rivers. The findings of this study may also be applicable to other large, deep bodies of water elsewhere.
Author Institution: Division of Water Quality Planning and Assessment, State of Ohio Environmental Protection Agency
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