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

The composition and spatial distribution of the cephalopods in the eastern Adriatic and the eastern Ionian Sea were analysed based on the trawling campaigns performed in spring-summer period during 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 an experimental 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 Adriatic, 21 in the south Adriatic region and 26 in the eastern Ionian area. Results of the multivariate analysis revealed the existence and persistence of three main species assemblages related to the depth gradient, with minor differences between regions. Eledone moschata, Loligo vulgaris and Alloteuthis media were dominant in the assemblage related to the upper continental shelf. Eledone cirrhosa, Illex coindetii and A. media were most abundant in the group related to the transition zone and the third assemblage, observed only on the middle slope of the south-eastern Adriatic, was characterized by the highest biomass percentage of the species L. vulgaris, Todaropsis eblanae and Pteroctopus tetracirrhus. Abundance indices calculated for commercially important species 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 total variation of the abundance of these species.

cephalopods; composition; distribution; Adriatic Sea; Ionian Sea

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