The first record of Gasterosteus aculeatus L. 1758 (Pisces: Gasterosteidae) in the Yugoslav section of Danube

Abstract

The threespine stickleback, Gasterosteus aculeatus L. 1758, is a common species in marine, brackish and freshwater habitats, distributed across boreal and temperate regions between 32o and 70o of north latitude (Ziuganov 1991, Rodewald & Foster 1998). Three typical morphs of this species are distinguished: 1. trachurus, the completely plated morph; 2. semiarmatus, the partially plated morph; and 3. leiurus, the scarcely plated morph (Fig. 1). The existence of a fourth morph is reported in some papers. Such a phenotype was reported from a few autochthonous populations (Ahnelt et al. 1998) and it is designated as a low plated morph with a keel, namely as "leiurus with a keel" (Ziuganov 1983). Several authors have published records of the species G. aculeatus in the Danube. Banarescu (1964) indicates that this species is present in the Danube delta. A record of one specimen of G. aculeatus in the Danube near Budapest was published by Berinkey (1960), while Balon (1967) published a record of two specimens of G. aculeatus from the Danube south of Bratislava (km 1864). Bastl (1970) gives a record of one specimen of this species from the same part of the Danube (km 1864) and one specimen from km 1829 of the Danube river course (Bastl 1976). He supposes that G. aculeatus is regularly present in the Bohemian-Hungarian part of the Danube, but that its fishing is sporadic. The opinion stated by Balon (1967), namely that spreading of the G. aculeatus population in the Danube was done by aquarists, is in agreement with the data given by Ahnelt et al. (1998). He states that this species was introduced in the system of the Danube and Rhine in Austria about 130 years ago, most probably by aquar­ists, and that this population is not only maintained there, but has also spread through all parts of these two river systems. No records from the Yugoslav part of the Danube have been published until now.