Theses and Dissertations

Title: Effect of water hyacinths and fertilization on bluegill and redear sunfish production in experimental ponds

Name: Wahlquist, Harold

Degree: MS

Chair: Dr. J.S. Dendy

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1969

Pages: 99

Keywords: Water Hyacinths,Fertilization,Bluegill,Redear Sunfish.


An experiment was conducted to determine the effect of water hyacinths and fertilization on bluegill and redear sunfish production in 18 0.1-acre ponds at the Auburn University Fisheries Research Unit, Auburn, Alabama from April 5 through November 20, 1967. The fish were stocked together at a rate of 4,000 fingerlings per acre. Of the 18 ponds, 9 contained hyacinth rafts covering 10% of the surface area while the other 9 ponds were free of hyacinths. Three treatments of fertilization (0-0-0, 0-8-0, and 8-8-0 as N, P, K) were applied (1O applications as replicates to separate ponds to stimulate the growth of hyacinths and fish-food organisms. Monthly samples showed that the hyacinths responded favorably to the fertilizer treatments through greater root growth. Standing crops upon draining were: 77.9 tons per acre receiving 0-0-0 treatment: 245.7 tons per acre receiving 0-8-0 treatment: and 263.8 tons per acre receiving 8-8-0 treatment. On two occasions pH, dissolved carbon dioxide, dissolved oxygen, temperature and total carbon were measured in all ponds. Greater numbers and dry weights of fish-food orcanisms were obtained from roots per m2 of water hyacinths per month in 0-0-0 ponds than in either 0-8-0 or 8-8-0 ponds. Snails and odonate nymphs were dominant in 0-0-0 ponds. Numbers of amphipods and midge larvae did not differ significantly between the three fertilizer treatments. Low numbers and dry weights of fish-food organisms along with high final weight of fish in 0-8-0 and 8-8-0 ponds containing hyacinths was probably due to heavy cropping by the bluegill and redear sunfish. In the control (0-0-0) ponds the mean standing crop of fish at draining time was approximately the same (41.0 pounds per acre in hyacinth ponds: 45.2 pounds per acre in non-hyacinth ponds). The mean standing crop from 0-8-0 and 8-8-0 ponds was at least twice as great in non-hyacinth ponds (131.0 pounds per acre in 0-8-0 ponds: 150.9 pounds per acre in 0-8-0 ponds) as in hyacinth ponds (51.3 pounds per acre in 0-8-0 ponds: 72.9 pounds per acre in 8-8-0 ponds). The reduced fish production in hyacinth ponds was probably due to competition for nutrients between the water hyacinths and the plankton food-chain, and to the reduction of "edge" for fish-food organisms on the roots .

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