Title: Is there evidence of inbreeding in African catfish (Clarias gariepinus) culture in Nigeria?

Final project
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Supervisors: Helgi Thorarensen , B. O. Omitoyin


Anecdotal reports from fish farmers and government officials in Nigeria suggest that inbreeding may be a problem harming the availability of quality seed for the culture of African catfish although there is a paucity of studies and clear statistical evidence for this. African catfish broodstocks were collected from 10 different farms (Abuja, Benue, Kaduna, Kano and Adamawa and 5 farms in Oyo) and major rivers in Nigeria. The performance of catfish progeny produced from pure farm bred strains (10 tanks), hybrids formed by breeding together fish from different farms (5 tanks) and the progeny of wild fish (1 tank) was compared. Water quality, survival rate, specific growth rates and weight gain were monitored. The SGR of the wild fish was highest, lowest in the pure farm strain and intermediate in the hybrids which is accounted for by differences initial body mass. This suggests that the growth performance of the aquaculture fish has neither improved nor deteriorated compared with wild fish. The survival rate of the pure aquaculture strains was better than that of hybrids or wild fish. These results show no evidence of inbreeding depression of the aquaculture African catfish in Nigeria. This suggests that the perceived problems with production performance of African catfish in Nigeria could be attributed to other causes such as variation in the quality of the fish originating from different fish farms. These differences may relate to genetic differences between farm strains or differences in management practices of different hatcheries. It is important to note that adequate management practices still need to be put in place to maximize the potential of African catfish stocks in Nigeria. The growth performance of the different strains may be used as a guideline to form a base population for genetic selection to improve performance of C. gariepinus in Nigeria.

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