Theses and Dissertations


Title: Preliminary studies with hybrid tilapia, Tilapia aurea Trewavas x T. mossambica Peters

Name: Avault, Jr James William

Degree: PhD

Chair: Dr. E.W. Shell

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1966

Pages: 54

Keywords: Hybrid Tilapia,Tilapia aurea Trewavas,Tilapia mossambica Peters.

Abstract:

Preliminary studies were conducted with hybrid tilapia, female T. aurea x male T. mossambica and reciprocal. Both hybrids were easily produced by natural spawning in vinyl-lined pools. The hybrids grew faster and had a better food conversion and survival than their parents. Of 328 female T. aurea x male T. mossambica hybrids examined, 71.6 per cent were males. Of 191 female T. mossambica x male T. aurea hybrids, 70.6 per cent were males. In cold tolerance tests T. mossambica began dying at 50oF in one test and 55oF in a second test. Both hybrids did not begin dying until the water temperature was lowered to 45oF. T. aurea began dying at 45oF also, but was hardier than the hybrids, in that some individuals remained alive even after all hybrids had died. In microhematocrit studies both hybrids had significantly higher values than either parent. However, as the water temperatue was lowered to 60oF and lower, there was not significant difference between hybrids and parents. Of all the possible meristic counts and morphometric comparisons, the gill raker count was the most reliable for separating hybrids from parents. Of male fish, T. mossambica averaged 17 gill rakers, both hybrids 19, and T. aurea 23 respectively. Female hybrids had similar values as male hybrids and female parents had similar values as male parents. In a fertility test the F1 generation spawned readily. Of 238 female T. aurea x male T. mossambica F2 hybrids examined, 92.4 per cent were males. Of 191 of the reciprocal cross 89.5 per cent were males. The average gill raker count was 20 for the female T. aurea x male T. mossambica F2 hybrid, and for the reciprocal cross.

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