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 super(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 plus or minus 4,122 eggs. In average, the overall relative fecundity of females was 325.37 plus or minus 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).Original Abstract: La reproduction de Sardina pilchardus (Walbaum, 1792) a ete etudiee entre juillet 2011 et juin 2012 dans le golfe d'Annaba (Nord-Est algerien). Le sex-ratio etait globalement en faveur des femelles (1,26 : 1 ; chi super(²) = 25,77). Sur un total de 2 266 specimens echantillonnes, 1 076 etaient des femelles 47,48%), 853 des males (37,64%) et 337 des immatures (14,88%). Les immatures etaient mieux representes dans les petites classes de taille, comprises entre 9 et 11 cm. Le suivi mensuel du rapport gonadosomatique (RGS) et les examens macroscopique et microscopique des gonades ont montre que la periode de reproduction de cette espece se situait entre octobre et mars. Le coefficient de condition presentait deux pics, l'un en novembre et l'autre en avril. La taille a la premiere maturite sexuelle chez les males et les femelles etait de 11,5 cm et 11,28 cm, respectivement. La fecondite absolue moyenne des femelles a ete estimee a 7 382 plus or minus 4 122 oeufs. La fecondite relative moyenne globale des femelles etait de 325,37 plus or minus 142,48 oeufs/g. Des relations lineaires entre la fecondite absolue et la longueur totale, le poids total, le poids somatique, ou le poids des ovaires ont ete observees, cette derniere presentant une forte correlation (r = 0,73).