Fisheries Research 68 (2004) 171–187 Fish species assemblages and geographical sub-areas in the North Aegean Sea, Greece A. Kallianiotis ∗ , P. Vidoris, G. Sylaios National Agricultural Research Foundation, Fisheries Research Institute, 640 07 Nea Peramos, Kavala, Greece Received 13 September 2002; received in revised form 8 December 2003; accepted 30 December 2003 Abstract The faunal composition and species abundance indices, according to data collected during 1996–2000 within the framework of the Mediterranean International Trawling Survey Program (MEDITS) at 65 sampling sites in North Aegean Sea and its surrounding coastal basins, were used to determine fish species assemblages, their geographical distribution and temporal variation. A principal component analysis (PCA) was applied to detect fish species associations and 11 principal axes were extracted, accounting for the 67.1% of system’s variance. According to these fish assemblages, three main geographical areas were distinguished in the North Aegean Sea: the Thracian Sea, Thermaikos gulf and the southern part of the sampled area, between the coast of Asian Minor and the Eastern coast of the Greek peninsula. These areas could be used for future multi-species fishery management purposes, related to the particular environmental conditions prevailing in each unit. © 2004 Elsevier B.V. All rights reserved. Keywords: Species assemblages; Fishing areas; North Aegean; Greece 1. Introduction Fisheries research conducted until now in Greek seas on demersal species assemblages is mostly con- centrated in the South Aegean Sea (Tsimenides et al., 1991; Tserpes et al., 1999; Kallianiotis et al., 2000). Compared to the South Aegean, where there are steep depth gradients with a limited continental shelf, the North Aegean is characterized by an extensive con- tinental shelf, formed by the sediment provided by six large rivers (Axios, Aliakmon, Pinios, Strymon, Nestos and Evros) (Lykousis and Chronis, 1989). These rivers in conjunction with Black Sea water, flowing through the Bosporus and Dardanelles Straits at a rate of 190 km 3 per year (Unluata et al., 1990), ∗ Tel.: +30-59-4023637; fax: +30-59-4022222. E-mail address: akallian@otenet.gr (A. Kallianiotis). reduce the surface water temperature and salinity of the North Aegean Sea (Yuce, 1995). Three aligned depressions (more than 1600 m deep) comprise the North Aegean Trough and isolate deep North Aegean water masses from the central and South Aegean Seas. The Mediterranean fishery is characterized by a multi-species composition, where many commercial species appear seasonally in the catches (Reina-Hervas and Serrano, 1987; Spanier et al., 1989; Stergiou et al., 1997). This characteristic creates difficulties in the definition and application of management measures. The identification of major geographical areas based on similar ecological communities found in respec- tive depth zones and areas with related hydrographic characteristics, could facilitate the definition of some management measures. The definition of homoge- neous assemblages persistent in time and their man- 0165-7836/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.fishres.2003.12.007