Période de reproduction et maturité sexuelle de <Liza aurata> (poisson, Mugilidae) des côtes Est et Sud tunisiennes

Abstract

 During the period, may 2000 and December 2001, samples of golden grey mullet samples were collected in different points of landing coastal fishing in Eastern and Southern Tunisia. The total number, monthly collected, reached 1245 individuals (678 males and 567 females). The total length was ranged between 14 and 36,5 cm. Three parameters linked to the spawning period and the physiology of the fish were monthly followed for the two sexes. The GSI (gonado-somatic-index) showed that the spawning period occurs between October and November, the LSI (liver-somatic-index) and the Kc (Condition factor) indicated that the golden grey mullet uses liver and muscles reserves to develop its gonads.During the maturation period, the examination of 600 individuals (285 females and 315 males) which the total length was ranged between 16 and 28 cm, allowed the following of the proportions of sexual matured individuals in each length class (interval is 1 cm). To estimate the length of first sexual maturity, L50 that corresponds to 50% of sexual matured individuals, we
applied to the observed data a Software (FSAS) based on the non linear adaptation of Marquardt (Saul et al., 1987). The relation that estimated L50 is 1/(1+exp-(r(L-L50))). L50 was for males 21,41 cm, for femeles 21,95 cm and for both 21,58 cm.