Length-weight relationship and fecundity of C. Gariepinus from river Niger

Abstract

Length-weight relationship and fecundity of C. gariepinus from River Niger was the focus of this study. A total of 2039 C. gariepinus was used for the study of male: female sex ratio while 100 mature males and females were used for other aspects of the fecundity studies. The total length of C. gariepinus used for this study ranged from 210mm to 430mm (mean=306.4±5.32).A total of 844 (41.39%) males and 1195 (58.61 %) were females. This gave a male female ration of 1:1.42 in favour of the females. In the montwhs of June, July August and November 2001, there was a significant (P2:_0.05) departure in favour of number of females from 1:1 male-female sex ratio of the C. gariepinus. In the months of October, December, January, February, March, April and May there was no significant difference (P2:_0.05) in the number of male and female C. gariepinus. The mean fecundity of female C. gariepinus was 23,994±19,618 eggs (n = 100). Fecundity was positively correlated with total length (TL), body weight (BW), and Ovarian Weight (OW). GSI values in females fishes, ranged between 10.22±2.7 to 17.39±1.4 and peaked in July while the lowest GSI was recorded in October and November 2001. Percentage of matured males reached its peak (32%) in March of 2001 and females it peaked (48%) a month later in May. The co-relation co-efficient (r) in the length-weight relationship were 0.8955 for males, 0.6906 for females and 0.9305 for both males and females. All regressions were highly significant (p<0.01). The values of the slope (b) for males, females and combined sexes were 2.21, 1.11 and 2.16 respectively and are significantly (p<0.01) lower than the theoretical 3.0 which indicated a negative allometric growth in C. gariepinus of river Niger.

Key Words: Length weight, Fecundity, C. gariepinus Niger River.