University of Khartoum

Biological Aspects of Oreochromis niloticus and Labeo niloticusfrom Khashm El-Girba reservoir and Atbara River, Kassala State, Sudan

Biological Aspects of Oreochromis niloticus and Labeo niloticusfrom Khashm El-Girba reservoir and Atbara River, Kassala State, Sudan

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Title: Biological Aspects of Oreochromis niloticus and Labeo niloticusfrom Khashm El-Girba reservoir and Atbara River, Kassala State, Sudan
Author: Abdalla, Mutasim Yousif Mohamed
Abstract: This study was aimed to investigate some biological aspects of Oreochromis niloticus and Labeo niloticus in Khashm El-Girba reservoir and Atbara River, such as: abundance, length-weight relationship, age, condition factor, sex ratio, gonado-somatic index, the main spawning season and to estimate fecundity and its correlation with standard length, body weight and gonad weight. The survey was conducted during December 2015 to November 2016. Samples were collected bi-monthly from three sites namely: Um Aswad (Atbara River), El-Remila and El-Monaba (The reservoir), using seine beach net of 1.2, 4 and 7 cm stretched bar mesh. Abiotic parameter including temperature, pH, conductivity and water transparency were recorded from all sampling sites monthly, and only the effect of temperature was examined against some biological aspects.A total of 1595 O. niloticus and 1190 L. niloticus specimens were collected from all sampling sites. Out of the total catch,O. niloticus was found dominant in Khashm El-Girba reservoir, and contributed to about 25.67% and 19.15%at El-Remila and El-Monaba, respectively;while, L. niloticus was found to be dominant in Atbara River, and constituted about24.21%.This study indicated two increase periodsof abundance for O. niloticusin the upper stream and only one increase period of abundance downstream, whereas, two periods of increase for L. niloticuswere observed at all sample sites.Length-weight relationship of both species indicates allometric growth pattern (b≠3).Age of O. niloticuscollected during this study ranged between 0+ to 4+ years andbetween 0+ to 3+ for L. niloticus.Mostof specimens collected of both species were of age 1+. In this age femalesO. niloticus were dominant, whereas females and males of L. niloticuswere about equal in numbers, except in downstream where females were dominant.Mean condition factor of O. niloticus ranged between 2.547 to 3.560 and between 1.671 to 2–548 for L. niloticus. Sex ratio was 1:1 for both species. Gonadosomatic index of O. niloticus females ranged between 1.965 – 2.620 and 0.434 – 0.439 for males, with two periods of increase, and this verify two breeding seasons of this species.The gonado-somatic index of L. niloticus showed one period of increase, and ranged between 1.281 -1.795 and 0.499 – 1.701 for females and males respectively.Fecundity of O. niloticus ranged between 138 – 1701 eggs with an average between 481.715 (Um Aswad) and 638.712 (El-Remila); correlation of fecunditywith gonad weight, body weight and standard length was noted to range from high to low in that order where (r) is 0.82707,0.50864 and 0.51711 respectively.The outcome of this study indicates that both species are dominant in Khashm El-Girba reservoir and Atbara river, length-weight relationship indicates allometric growth pattern, condition factor indicate good health for both species, sex ratio was same 1.0:1.0, two spawning seasons for O. niloticus while one breeding season forL.niloticus. The low fecundity of O. niloticushas a high correlation with gonadal weight (r=0.82708) but low correlation was observed with weight (r=0.50874) and standard length (r=0.47612).Spawning season of L.niloticus coincided with flushing operation of Khashm El-Girba reservoir.
URI: http://khartoumspace.uofk.edu/123456789/26550


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