Abstract
The present work is a first contribution to the knowledge of the biology of the spider crab Maja crispata along the Tunisian coasts, with particular reference to the sex-ratio and size (carapace width) structure as well as the morphometric characterization of six subpopulations living in both south-eastern (Gulf of Gabes) and northern (Gulf of Tunis) coasts of Tunisia. Results of this study showed that the Tunisian population of M. crispata is generally male-biased with some spatial variations of the sex-ratio, probably due to the migratory behavior of the species. The comparative analysis of size structures of all studied subpopulations highlighted also some spatial variations, with a unimodal size distribution and a clear prevalence of individuals belonging to the size class of 35-40 mm. Concerning the morphometric characterization of M. crispata, the principal component analysis showed a main separation of the spider crabs examined with respect to the gender. Based on the dendrogram of hierarchic classification, a separation was also highlighted with respect to sampling sites and regions. The spatial variations of the sex-ratio, size structure and morphometry features of M. crispata could be due to the spatial variations of environmental factors (e.g. temperature, trophic resources) that may influence the biology of the species.