Pêche et production animale

Abstrait

The Sex Ratio, Gonadosomatic Index, Diet Composition and Fecundity of African Pike, Hepsetus odoe (Bloch, 1794) in Eleyele Lake, Nigeria

Kareem OK, Ajani EK, Orisasona O and Olanrewaju AN

The Sex ratio, Gonadosomatic index, Fecundity and Diet composition of Hepsetus odoe in Eleyele lake, Southwest, Nigeria were investigated to document aspect of biology and population dynamic of the species. This will serve as baseline information necessary for bringing the species to culture. Samples (n=205) of H. odoe were collected on a bimonthly basis from Eleyele Lake using gill nets and baited long line over a period of 3 months (June to August, 2012). Specimens were measured for Length (cm) and Weight (g) using graduated metre rule and Top load weighing balance (Model) respectively. The Stomach was opened for Gonad examination and Food content analysis. The total length ranged from 20.3-31.9 cm (males), 21.8-35.8 cm (females) while the total body weight ranged between 51.0-219.0 g (males) and 95.0-250.0 g (females) Sex ratio of 1: 2.73 (♂:♀) was observed. Gonadosomatic index ranged from 0.64 to 15.54% with a mean of 4.4 ± 0.12%. Three stages (Immature, Maturing and Matured) Ovary were observed for females. Fecundity ranged from 245 to 3,920 eggs with a mean of 2082.5 eggs. The relationships of fecundity with body weight and gonad weight were highly significant (P<0.05), while those between fecundity and standard length was not significant (r2=0.026, P<0.05). Out of 205 stomach examined, 71 (34.63%) was empty while 134 (65.37%) contained various food items. The dominant food items were Fish (tilapia), Daphnia, Copepods and Insects, and occurred in 51.0%, 14.2%, 12.0 and 10.5% stomach respectively. Cyclops, Mysis, Chydorus, Euplypha and Hemisiriella had the least occurrences of 1.5%, 1.5%, 0.75%, 0.75%, and 0.75% respectively suggesting the species to be Carnivorous. This study gives relevant clues on reproductive biology and feeding habits required for artificial propagation of H. odoe.