Turkish Journal of Fisheries and Aquatic Sciences
2003, Vol 3, Num, 1 (Pages: 5-10)
The Reproductive Biology of Brycinus nurse (Paugy 1986), Pisces: - Characidae in Asa Reservoir, Ilorin, Nigeria
Joseph Kayode Saliu 1 ,Solomon Olukayode Fagade 1
1 University of Lagos, Department of Zoology, Marine Biology and Fisheries, Akoka, Lagos, Nigeria
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A total of 980 specimens of Brycinus nurse caught in Asa reservoir from November 1991 to October 1993 were
examined for reproductive attributes. Female dominance was observed within the population, with a sex ratio of 1.0 male to
1.78 females. The fish spawns during the rainy season from March to August, with peak spawning in March, June and July,
months coinciding with the onset of the rains and flooding. The Gonadosomatic Index (G.S.I) of the population of B.nurse in
Asa reservoir ranged between 0.02-29.25% with a mean of 6.43 varying with season, size of fish, sex and stage of gonadal
maturity. The absolute fecundity ranged between 1,720 - 68,700 eggs with a mean of 18,281 eggs while relative fecundity
ranged from 19,933 to 849,453 eggs /kg with a mean of 345,000 eggs /kg of body weight. The fecundity increased with
gonad weight, but showed no significant relationship with body size. Egg diameter ranged from 0.49 to 0.82 mm with a mean
of 0.63 mm. The River Asa population of B.nurse had lower mean values of G.S.I, egg diameter, and relative fecundity but
higher estimates of absolute fecundity than other populations, previously studied. These differences were thought to have
emanated from differences in geographical location.
Keywords :
Brycinus nurse, Characidae, Reproductive biology, Nigeria