Stocking grass carp Ctenopharyngodon idella is a commonly applied technique used to control nuisance aquatic vegetation in reservoirs. Factors that influence the degree of aquatic vegetation control are stocking density, regional climate, abundance and species composition of the aquatic plant community, and relative grass carp feeding preferences for the plant species. We evaluated high-density grass carp stocking in a reservoir for control of parrot-feather (Myriophyllum aquaticum, an invasive aquatic plant that is not preferentially consumed by grass carp) and the associated effects on water quality and native fishes. Lookout Shoals Lake, a piedmont North Carolina reservoir, was stocked with triploid grass carp at a density of 100 fish per vegetated hectare. Parrot-feather biomass in the lake was significantly reduced three months after grass carp stocking, compared to biomass in in-situ exclosures. During the second year after grass carp stocking, parrot-feather biomass in the lake compared to biomass in in-situ exclosures indicated continued control, but unexplained lack of growth within most experimental exclosures precluded biomass analyses. Increases in ambient water chlorophyll a, reactive phosphorus, and nitrate-nitrite concentrations were measured after grass carp stocking. We evaluated the native fish community using seasonal shoreline electrofishing before and after grass carp stocking. Total catch for all fish species in aggregate at shoreline transects was not significantly different after grass carp stocking by number or biomass. Catch rates of largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and redbreast sunfish Lepomis auritus were not significantly different after grass carp stocking, but yellow perch Perca flavescens catch rates were significantly lower. The biological significance of fish distribution changes and long-term effects on lake biota remain undetermined. Our results demonstrate that intensive grass carp stocking can control an invasive aquatic plant that is not preferentially consumed by grass carp, and reveal associated changes in water quality and fish distributions.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-09132008-145505 |
| Date | 14 November 2008 |
| Creators | Garner, Alan Brad |
| Contributors | Dr. Kenneth H. Pollock, Dr. Thomas J. Kwak, Dr. Joseph E. Hightower |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-09132008-145505/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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