Observations on gillnet catches of Kariba Tilapia, Oreochromis mortimeri, from Bumi Basin of Lake Kariba, Zimbabwe
Mhlanga, W. (Lake Kariba Fisheries Research Inst., P.O. Box 75, Kariba (Zimbabwe))
Gillnet catches of Oreochromis mortimeri (Trewavas) were studied in the Bumi Basin of Lake Kariba in 1988 and 1989. Total length (TL) was positively correlated with standard length (SL). The linear relationship between TL and SL was TL=1.91 + 1.22 SL (r2=0.982). The relationship between SL and weight in g (W) was of the form W=0.12 SL raised to 2.67. Maximum standard length (L max) was 33 cm and asymptotic length (Loo) was 34.7 cm. Monthly ratios of male to female varied between 0.6:1 and 13:1. The mean ratio was 57.4 percent male:42.6 percent female. Monthly condition factors varied between 3.19 and 5.11 in males, and between 3.18 and 5.14 in females. Catches were higher in 1989 compared to 1988 and possible reasons for these differences are discussed
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