Assessment of a rotenone application event at Mormon Island West lake in Central Nebraska

Authors

Keith D. Koupal, Nebraska Game and Parks CommissionFollow
Brian C. Peterson, University of Nebraska at KearneyFollow
Casey W. Schoenebeck, Univesity of Nebraska at KearneyFollow

Date of this Version

3-11-2013

Citation

Transactions of the Nebraska Academy of Sciences (2013) 33, 1–6

Comments

Copyright (c) 2013 Keith D. Koupal, Brian C. Peterson, and Casey W. Schoenebeck

Abstract

Fisheries managers applied rotenone to Mormon Island West in August of 2010 to renovate a fish community that was hypothesized to be unbalanced (i.e., dominated with gizzard shad and common carp) based on standardized survey results. We estimated species-specific biomass following the lake renovation to provide a baseline biomass estimate for a sand pit lake and to evaluate the effectiveness of standardized sampling gears. Gizzard shad (Dorosoma cepedianum) were abundant in all sampling gears, but mostly stock-size (>175 mm total length) and larger individuals were caught in gill and trap nets and sub-stock (≤175 mm total length) individuals were caught with boat electrofishing. The abundance of common carp (Cyprinus carpio) found after rotenone application was better represented from boat electrofishing sampling than gill nets. The total biomass found in Mormon Island West at the time of lake renovation was 982.1 kg/ha with 90% of that biomass composed of gizzard shad and common carp. The priority management species of largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), and channel catfish (Ictalurus punctatus) comprised only 3% of the total biomass. Overall, this lake appears to have been a good candidate for a rotenone treatment as other management approaches were not likely to correct the existing imbalances.