168 Bulletin UASVM Animal Science and Biotechnologies 70(1)/2013, 168-174 Print ISSN 1843-5262; Electronic ISSN 1843-536X The Structure and Diversity of Fish Communities from Predeltaic Danube Area Petronela G. (CĂLIN) SANDU 1) , Lucian OPREA 1) , Victor CRISTEA 1) , George TIGANOV 2) 1) Faculty of Food Science and Engineering, ”Dunarea de Jos” University of Galati, 47 Domnească Street, 800008 Galati, Romania; Georgiana.Sandu@ugal.ro 2) National Institute for Marine Research and Development “Grigore Antipa”, 300 Mamaia Blvd., 900581 ConstanŃa, Romania Abstract. The paper is presenting some aspects regarding the structure of fish communities from 22 Km of predeltaic sector of Danube River, between the mouth of Siret River (km 155) and Prut River (Mm 72.5). The aim of the study is to assess the ecological status of the area, using some analytical and synthetic ecological indices, but also diversity and equitability indices. From March to December 2010, in four fishing areas (km 150-151, Mm 77-78, Mm 76-77, Mm 74-74.5), 14692 fish of 29 species, from 6 families and 6 orders, were collected. The best-represented family is Cyprinidae with 16 species. The numerical abundance ranged between 1fish/species (zingel, Danube streber and schraetzer -rare species) and 7019 fish/species (pontic shad -abundant specie). The Pontic shad (47.77%) and Azov shad (11.20%) are eudominant species, having the biggest potential in fish productivity; common bream (9.15%) and common carp (7.36%) are dominant species. Keywords: Danube, fish communities, abundance, diversity, ecological significance INTRODUCTION The structure and the diversity of fish communities is an important feature in the system dynamics because changes in diversity reflect changes in the ecosystem processes, such as productivity, energy pathways and material flow, disturbance regimes, abiotic stress and biological interactions (Grall et al., 2005). A good management of the interactive components of the fishery should always lead to a durable exploitation, in terms of biodiversity conservation and protection. In the last years, however, unfortunately, the over-exploitation of the fish communities at the same time as the continuous degradation of the habitats led to the decline and even to the extinction of some fish species (Bram et al., 2003). MATERIALS AND METHODS Fishing area. The study area is represented by a region in the predeltaic Danube, located between the Siret River Mouth (km 155) and the Prut River Mouth (Mm 72.5). This region has approximately 22 km, representing the length of the Danube sector in Galati County. Monthly, systematic measurements have been made in 4 fishing areas: Galati area (km 150-151), Condrea area (Mm 77-78), Muresanu area (Mm 76-77) and Plopi area (Mm 74-74.5). Fishing effort, fishing gears and methods. The fishing has being made through active methods, on areas, with filtering gear: gill net and trammel net type. The constructive