Composition and distribution of the cephalopod fauna in the eastern Adriatic and eastern Ionian Sea

The composition and spatial distribution of cephalopods in the eastern Adriatic and the eastern Ionian Sea were analyzed based on the samples collected during the trawling campaigns performed in 1996, 1997, 1998, and 2000 in the framework of the MEDITS Project "International Bottom Trawl Survey in the Mediterranean Sea". Cephalopod samples were collected with a bottom trawl net, at sea depths ranging between 21 and 800 meters. A total of 32 species was registered, out of which 26 were found in the northern and central eastern Adriatic. 21 in the south eastern Adriatic region, and 26 in the eastern Ionian area. Results of the multivariate analysis revealed the existence of three main species assemblages related to the depth gradient, with minor differences between regions. Eledone moschata, Loligo vulgaris, and Alloteuthis media had the hi-hest biomass percentage in the assemblage related to the upper continental shelf. The assemblage observed on the middle slope of the South eastern Adriatic was characterized by the highest biomass percentage of L. vulgaris, Todaropsis eblanae, and Pteroctopus tetracirrhus. In the transitional zone, related to the lower continental shelf and upper slope, the dominant species were Eledone cirrhosa, Illex coindetii, and A. media. Abundance indices calculated for the most important commercial species in the area investigated-L. vulgaris. I. coindetii, T. eblanae, E. cirrhosa, and E. moschata -showed that the depth, sub-area, and annual recruitment were important factors affecting the variation of the abundance of these species.