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Aspects of the Reproductive Biology of Pellonula leonensis (Boulenger, 1916; Clupeidae) in the Lower Nun River, Niger Delta
並列摘要
Aspects of the reproductive biology (gonadal development/spawning period, size-at- maturity and sex ratio) of Pellonula leonensis was studied from May 2001 to April 2002 in the Lower Nun River, Niger Delta. Sexes were separated by internal examination of the gonads after dissection of fish while gonad development was determined macroscopically and grouped into a 4 broad stage scheme: I-immature, II - mature, III- ripe and IV - spent. Mature individuals were found all year round with peaks in September/October and May/June indicating that P. leonensis spawned all year round with peaks in those periods. Maturity occurred earlier in males than in females; 50% of both sexes matured at 5.5-6.5cm Total Length (TL). Females were dominant in the rainy season while males dominated in the dry season, but overall, the sex ratio did not deviate from the 1: 1 ratio.