engleski

Translocated predators in freshwater ichthyofauna of the Adriatic basin

The Adriatic basin is renowned for its highly endemic freshwater ichthyofauna, in which almost every river has its own unique freshwater fish community. These fish communities are also characterized by the lack of true predator species. However, the translocation of predator species (pike, European catfish and pikeperch) from the Danube drainage to the Adriatic basin has caused changes to fish communities, and the repercussions are yet to be systematically analysed.While pikeperch and European catfish populations, as a translocated species, do not readily expand in open watercourses, pike is an excellent example of an invasive species whose populations expand rapidly in all invaded watercourses. To date, pikeperch has only been recorded sporadically in open rivers (Mirna and Neretva), though it has well established populations in artificial reservoirs (Butoniga and Tribalj) and European catfish has been recorded in Tribalj reservoir, Vrana Lake near Biograd and Lika River with Krušćica reservoir. On the other hand, pike has been recorded to have established populations in the following watercourses: Mirna River with Butoniga reservoir, Gacka River with Švičko reservoir, Lika River with Kruščica reservoir, Cetina River with its reservoirs, Vrana Lake on Cres Island, Vrana Lake near Biograd, Prološko Blato Lake, Šarana jezera Lakes near Knin. Recent findings suggest that pike has also invaded the Krka and Vrljika Rivers.At most of these localities, the pike populations have been present for several decades and the impact on local ichthyofauna can be assesed. Recent findings in the Krka and Vrljika Rivers, however, suggest that it is yet to be seen how the fish communities will respond to this invasion. It will be especially important to monitor the impact that pike invasion has on endangered soft-muzzled trout in order to take prompt and appropriate conservation actions.

pike, pikeperch, European catfish, endemic fish communities, translocated species, invasive species

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