The influence of hydrochemical and hydrological factors on the qualitative and quantitative structure of ichthyofauna from predeltaic Danube area.

Abstract

Thepaper is presenting some aspects regarding the influence of environmentalfactors on fish communities structure from Danube, between Siret River and PrutRiver mouth. Fish were collected from March to December 2010 in four fishingareas. During the year, 12064.23 kg, respectively 14692 fish of 29 species werecollected. Cyprinidae, the dominant family, 55.17% in term of number of species, was represented by 16 species (Cyprinus carpio, Carassius gibelio, Barbusbarbus, Abramis brama, Abramis sapa, Blicca bjoerkna, Leuciscus idus, Vimba vimba, Aspius aspius, Pelecus cultratus,Chondrostoma nasus, Ctenopharingodon idella, Hypophthalmichthys molitrix,Hypophthalmichthys nobilis, Scardinius erythrophthalmus, Rutilus rutilus).Other families had the following structure: Percidae (17.24%) with 5 species (Sanderlucioperca, Zingel zingel, Zingel streber, Perca fluviatilis, Gymnocephalusschraetzer), Acipenseridae (13.79%) with 4 species (Huso huso,Acipenser stellatus, Acipenser ruthenus, Acipenser gueldenstaedtii), Clupeidae (6.90%) with two species (Alosa immaculata, Alosa tanaica), Siluridae (3.45%) with one species (Silurus glanis) and Esocidae (3.45%) with one species (Esox lucius). The highest capture was 8217.62 kg (68.12%), duringthe spring season (March-May), followed by autumn season (September–November), with 1437.56 kg (11.92%). The water level and water flow showed highcorrelation with both number and total catch, respectively.