Theses and Dissertations


Title: Predation by the flathead catfish, Pylodictis olivaris (Raf.) on pondfish populations

Name: Hackney, P.A.

Degree: MS

Chair: H. S. Swingle

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 1965

Pages: 53

Keywords: Flathead catfish,bluegill,predator to prey ratio

Abstract:

The vulnerability of largemouth bass (Micropterus salmoides ), green sunfish (Lepomis cynaellus ), goldfish (Carrassius auratus ) and White catfish (Ictalurus catus ), to predation by flathead catfish in both plastic-lined pools and earthen ponds was investigated. Data indicated white catfish were significantly more vulnerable than either green sunfish or goldfish in plastic-lined pools. Experiments to evaluate predation and production of fingerling and adult flathead catfish in ponds were conducted. All flathead catfish flingerlings died in ponds containing established bluegill-fathead minnow populations while survival of largemouth bass fingerlings averaged 87.5 percent in the same ponds. Only 20 of 1,900 fingerling flathead catfish stocked in two 1.0-acre ponds contaminated with large numbers of green sunfish were recovered on draining. A stocking of 50 flathead catfish per acre into a pond containing a crowded bluegill population reduced, but failed to correct, overcrowding within a 48-week period. Two ponds in which brood tilapia and large flathead catfish were fed also failed to develop satisfactory populations. Production of forage fish larger than the 5-inch group was low in all ponds and ranged from 12.9 to 14.6 percent by weight of forage populations. F/C ratios ranged from 2.5 to 6.6. Growth of flathead catfish was rapid with increases in average weights ranging from 1.4 pounds in 320 days to 3.2 pounds in 105 days. Net production of flathead catfish ranged from 43.2 to 71.7 pounds per acre. Equations of the length-mouth width and length-depth relationships were calculated for flathead catfish with the aid of a digital computer. Regression coefficients for length-mouth width relationships between sexes of pond-reared fish differed significantly. A significant cubic reduction sum of squares was obtained for mouth width on length over a length range of 31 to 1066 mm, although the principal reduction sum of squares was linear over the major range of the data. The relationship of length-depth was curvilinear over a length range of 31 to 840 mm. Sex ratio of pond-reared flatheads was extremely skewed. Males outnumbered females by almost 9 to1. Mean length of males was significantly greater than that of females

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