Nkeonyeasua Florence OLELE, Prekeyi TAWARI-FUFEYIN and Josiah Chidiebere OKONKWO
Abstract: A total number of 338 specimens of Macrobrachium vollenhovenii were bought from fisher folks who fished from Ubeji, Jala and Soroghagbene; but marketed their landings at Ubeji. Specimens were collected at monthly intervals between March and November, 2011. The male to female sex ratio established was 1:2:3. The size at first maturity was 9.0 cm for males and 10.0 cm for females. The length–weight relationship revealed an increase in total length of each specimen as body weight increased. The regression coefficient ‘r’ was significant at p&< 0.05 for male (0.901) and female (0.644) specimens. An average condition factor of 3.9 and 2.74 was recorded for males and females respectively. The Gonado–Somatic–Index (GSI) was generally higher, especially during the month of July for females (0.60) than for males (0.50). Distinct histological changes were observed in the gonads of both sexes. Gonad development revealed five distinct stages (dominant, developing, developed, ripe and spent) for both sexes. Fecundity ranged between 5,540–28,470 eggs, and was highly correlated with total length (0.979) but not with body weight (0.185). Fecundity was highest in the month of July (20,113) and lowest in the month of August (6,140). It could be concluded that matured specimens probably spawn, in March and in July, when GSI were at their peaks. This pattern of breeding suggests that they were capable of multiple spawning within a single reproductive season.
Key words: length–weight relationship, condition factor, GSI, maturity stages, fecundity and Macrobrachium vollenhovenii