Reproduction and maturation of the gonads of Sardina pilchardus from the Gulf of Annaba (North-Eastern Algeria)

The reproduction of Sardina pilchardus (Walbaum, 1792) was studied between July 2011 and June 2012 in the Gulf of Annaba (North-Eastern Algeria). The sex ratio was in favour of females (1.26:1; chi(2) = 25.77). Among the 2,266 sampled fish, 1,076 were females (47.48%), 853 were males (37.64%) and 337 were immature (14.88%). Immature fish were better represented numerically in the small size class, between 9 and 11 cm. Monthly variations of the gonadosomatic index (GSI) and macroscopic and microscopic examinations of the gonads showed that the reproductive period of S. pilchardus occurred between October and March. The hepatosomatic index (RSI), adiposity and condition factor (K) showed variations not related to reproductive cycle. The size at the first sexual maturity was 11.50 cm in males and 11.28 cm in females. The mean absolute fecundity of females was estimated at 7,382 +/- 4,122 eggs. In average, the overall relative fecundity of females was 325.37 +/- 142.48 eggs/g. Linear relationships between absolute fecundity and total length, total weight, somatic weight, and ovarian weight were observed, this latter being highly correlated (r = 0.73).