Distribution patterns of two species of swimming crabs (Portunidae), Liocarcinus depurator (L.) and Macropipus tuberculatus (Roux), in the southwestern Adriatic Sea (Mediterranean Sea)

Quantitative data and length distribution data on the blue-leg swimming crab, Liocar- cinus depurator, and the knobby swimming crab, Macropipus tuberculatus, were collected during eight seasonal trawl surveys carried out from 1991 to 1995 in the Southwestem Adriatic Sea. The spatial distributions were analysed by means of geo- statistics, and the population demography was described. Referring to the kriging per species, L. depurator showed the highest abundance on the shelf bottoms (mostly in the northem zone of investigated area) and it appears to be more homogeneously dis- tributed during autumn season. M. tuberculatus showed the highest abundance on the lower shelf border and on the slope bottoms. Moreover, the presence of a 'spatial competition' rate between the species in the areas of bathymetric overlapping could be underlined as it was shown by seasonal kriging. The carapace length ranged from 13 to 40 mm in the blue-leg swimming crab, and from 12 to 30 mm in the knobby swimming crab.