Status of endangered fish species Aulopyge huegelii Heckel, 1843 (Teleostei: Cyprinidae) in the Buško Blato reservoir, Bosnia and Herzegovina

The Dalmatian barbelgudgeon, Aulopyge huegelii is a stenoendemic fish species restricted to the area of west Bosnia and part of Dalmatia. Its global IUCN species status is “endangered (EN)” according to the “B1ab (iii, v)” criterion. There are not enough reliable sources containing data on this species, particularly in the recent period. As primarily a groundwater fish, it was exceptionally well adapted to environmental conditions in the Busko Blato reservoir. Based on the recent findings, the status of this species has changed over the past several years. The main objective of this study was to characterise and determine the current status of the monotype species A. huegelii from the Busko Blato reservoir, through the analysis of its selected morphological and ecological features. During field research, we have gathered 88 individuals of A. huegelii , at just four neighbouring sites. A significant decrease in its population number is evident in comparison to previous studies. The results have shown its retreat into a small part of the reservoir which is connected with the groundwater system as its primary habitat, in order to escape from predators: the four new allochthone species in this ecosystem. Comparing the results with previous studies, it could be concluded that the Dalmatian barbelgudgeon is “returning” to its original morphological form i.e. groundwater fish form. All this could in perspective have significant consequences on the survival of the population of this species in the Busko Blato reservoir.