CROATIAN FAUNA 2009.- DANUBIAN BREAM

Danubian Bream - Latin: Ballerus sapa (Pallas, 1814) Foreign names: Danubian Bream, White-eye Bream (English); Zobel (German) The body of the Danubian Bream is laterally flattened and relatively high. The most conspicuous on its small head is the size of the eyes. The eyes are equal in diameter or bigger than the distance from the rostrum to the beginning of the eye. This does not apply to young fishes, in which the eyes are not a determination feature. The mouth is small and semi-inferior. The back is dark blue to greenish and the sides and the belly is silver. The anal fin is extremely long and extends to the tail and its base is three times longer than the base of the dorsal fin. The length of the anal fin covers one third of the body length. The outer edge may be darker. During the spawning season, males have skin warts on the body and fins. The scales are of medium size and there can be 47 to 54 of them in the lateral strip. The Danubian Bream usually reaches the length of 15 to 25 cm, or maximum 40 cm, and the mass of approximately 1 kg. Young fishes feed on zooplankton, whereas the adults feed on larvae of insects, molluscs and small crabs, and sometimes also on aquatic plants. It reaches breeding maturity in its third or fourth year. It spawns in April and May. Females lay up to 150 000 eggs on aquatic plants. They live in schools and are more active during the night. The Danubian Bream inhabits big lowland rivers, estuaries and backwaters. Its favourite spawning locations are more peaceful places in rivers with thick aquatic plants. Its habitats in Europe are the Danube basin and the rivers flowing into the Black Sea, the Caspian Sea and the Aral Sea, especially on the territories of the former Soviet Union. Its habitats in Croatia include the rivers flowing into the Danube: the Sava, the Drava and the Danube itself, as well as its bigger tributaries. The Danubian Bream is endangered by partitions, regulation and channelling of water streams, as well as by their pollution. According to the IUCN Red List, this species is Data Deficient (DD) in Croatia. Pursuant to the existing protection based on the law, the Danubian Bream is a strictly protected species. The international protection document mentioning this species is the Bern Convention (Appendix III).