Reproduction de la seiche Sepia officinalis Linné, 1758 (Mollusque, Cephalopode) du golfe de Tunis: étude morphologique et morphométrique

Abstract

The cuttlefish Sepia officinalis is an equal sex proportion species and distinguishes itself by a very clear sexual dimorphism. Sexual maturation corresponding to 50% rate of the population is attained at 9cm of mean size; then from the animal first life year. Considered by sex, the male sexual maturation is more precocious than that of female respectively at 8cm and 10cm of mean size. From different metrical relationships established between cuttlefish body, reproductive organs and sexual products, it appears that gonadic development may be forecasted in male by tractus growth and in female by appendage glands growth and otherwise, justifies the applying of index based in these parameters: gonado-somatic ratio (G.S.R.) and maturation index (M). The female full egg-laying season spreads from april to july with, however, one month later on that of male. The monthly evolution of relative condition index K and mean condition index Km are synchronous but are opposed to G.S.R. ratio. (BDO)