Length-weight relationship, condition factor and fecundity of the African Pike Hepsetus odoe (Bloch, 1974) in Eleiyele Reservoir, Ibadan, south-west Nigeria

摘要

Some aspects of growth and reproductive biology of Hepsetus odoe, a commercial fish species from Lake Eleiyele, were investigated from October 2010 to April 2011 to enhance effective management and sustainable exploitation. The pattern of growth was determined from the length-weight relationship (LWR) and the condition factor (AT). The reproductive features studied included fecundity, the gonadosomatic index (/G) and egg diameter. A significant relationship was found to exist (p < 0.05) between the body weight and the total length (La-) of fish. The exponential parameter b of LWR was 1.88. The mean K was 0.77 and the minimum mean K value (0.28) was recorded in the largest specimens. A significant difference in the condition factor was recorded between sexes and between size groups (p < 0.05). Fecundity ranged between 556 (for specimens with Lf 22.9 cm; total weight (Wj) 97.7g) and 2350 (for specimens with Lj 36.9 cm; W_T 266.9 g) eggs with the mean of 1469 eggs. The overall mean I_G was 1.12% withfemales having a higher mean /0 (1.61%) than males (0.66%). The mean egg diameter was 0.51 mm. The lower 6-value, egg diameter and fecundity recorded for this species in Lake Eleiyele might be accounted for by lake pollution caused by human activities.