Fecundity of two dominant fish species in Ado reservoir, Southwest Nigeria

The present study determined the fecundity and sex ratio of Oreochromis niloticus and Clarias gariepinus as the dominant species in Ado Reservoir, in Ekiti State, South West Nigeria between November 2011 and March 2012. The major fishing methods employed for collecting the fish specimens were cast netting and set netting. Biometric data such as total length, standard length and body weight measurements were recorded in the laboratory. Out of 40 C. gariepinus analyzed, 18 were males while 22 were females showing male to female sex ratio of 5:6. O. niloticus showed male to female sex ratio of 3:2 from 36 males and 24 females analyzed. Both C. gariepinus and O. niloticus showed high significant correlation between fecundity and gonad weight (r=0.84, P 0.05) for C. gariepinus and (r=0.72, P 0.05) for O. niloticus. Fecundity of O. niloticus ranged from 600eggs to 800eggs with a mean of 700eggs while C. gariepinus ranged from 4,000eggs to 7,200eggs with a mean of 5,588eggs. Most species of O. niloticus were not carrying eggs at the time of study. The study concluded that fecundity in the two species examined was low. This calls for an investigation into some prevailing conditions in the reservoir vis-à-vis availability and quality of food, the physical and chemical constituents of the water as well as the activities of fishermen operating in reservoir area.