THE INFLUENCE OF ENVIRONMENT CONDITIONS ON THE QUALITATIVE AND QUANTITATIVE COMPOSITION OF FISH COMMUNITIES FROM PREDELTAIC DANUBE SECTOR, BETWEEN SIRET RIVER AND PRUT RIVER MOUTH

Petronela Georgiana Calin Sandu, L. Oprea, N. Patriche, Daniela Gheorghe

Abstract
The aim of the paper is to analyse the influence of environment factors on the capture and fish communities structure from Danube, between Siret River and Prut River mouth. Fish were collected from April to December 2011 in four fishing areas. During the year, 6027 kg, respectively 4805 fish of twenty three breeds were collected. Cyprinidae, the dominant family, 60.87% in term of number of breeds, was represented by 14 breeds (Cyprinus carpio, Carassius gibelio, Barbus barbus, Abramis brama, Abramis sapa, Blicca bjoerkna, Leuciscus idus, Vimba vimba, Aspius aspius, Pelecus cultratus, Chondrostoma nasus, Ctenopharingodon idella, Hypophthalmichthys molitrix, Hypophthalmichthys nobilis). Other families had the following structure: Clupeidae (4.35%) with one breed (Alosa pontica), Acipenseridae (13.04%) with 3 breeds (Huso huso, Acipenser stellatus, Acipenser ruthenus), Percidae (13.04%) with 3 breeds (Sander lucioperca, Zingel zingel, Zingel streber), Siluridae (4.35%) with one breed (Silurus glanis) and Esocidae (4.35%) with one breed also (Esox lucius). The highest capture was 2728.5 kg (45.29%), during the spring season (April-May), followed by autumn season (September - November), with 560.45 kg (9.29%). The water level and water flow showed high correlation with both number and total capture, respectively.

Key words: fish communities, Danube, environmental factors, catch