213 * Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia and Montenegro ** Centre for Multidisciplinary Studies, University of Belgrade, 29 Novembra 142, 11000 Belgrade, Serbia and Montenegro Author for Correspondence: Dr. Predrag Simonović; phone +381 11 187 266, fax +381 11 368 500, mobile +381 63 864 93 40, e mail: pedja@bf.bio.bg.ac.yu ACTA ZOOLOGICA BULGARICA Acta zool. bulg., 56 (2), 2004: 213-222 Conservation Status of Two Eastern Balkan Endemic Fish Species in Serbia and a Proposal for Their Protection Saa Marić*, Aleksandar Hegedi**, Vera Nikolić*, Predrag Simonović* Abstract: All waters of the Aegean drainage in South-East Serbia are inhabited by the Macedonian trout Salmo macedonica (KARAMAN, 1924). Eastern barbel Barbus cyclolepis (HECKEL, 1814) and chub Leuciscus cephalus (L., 1758) were found only in the Dragovitica River and the minnow Phoxinus phoxinus (L., 1758) was recorded in the most downstream sections of the Ljubata and Dragovitica Rivers. The hydrological (e.g. physical, chemical) characteristics indicate a well-preserved environment and good life conditions for fish in those uniform aquatic ecosystems. Based on the population status and the criteria of the International Union for the Conservation of Nature (IUCN), the Lower Risk (conservation dependent) (LR(cd)) and Vulnerable (VU) conservation status were assigned in national range for the Macedonian trout and the eastern barbel, respectively. More stringent measures are necessary to protect eastern barbel and Macedonian trout. Key words: Struma River drainage, environment conditions, eastern barbel, Macedonian trout, IUCN conservation status, overfishing, conservation measures Introduction The endemic fish fauna of the Balkan Peninsula featuring the characteristics of the region is divided into western, Adriatic subregion, eastern, Pontic subregion, and south- ern, Aegean subregion, whereas its central part belongs to the Danube basin, with the Central European fish fauna. Serbia, which has the central position on the Balkans, contains a remarkable part of its ichthyofaunistic diversity, although in such small extent which imposes the need for the strong conservational care (SIMONOVIĆ 2001). The Aegean Sea basin is the least investigated one for fish of three marine drainages (Black, Adriatic and Aegean Seas) occurring in Serbia (SIMONOVIĆ 2001). Since 1988, the Environment Protection Bureau of Serbia has investigated the fish fauna of both the Lepenac River drainage in South Kosovo and the Pčinja River, both of which belong to the Vardar (i.e. Axios) River drainage (SEKULIĆ NENAD, pers. comm., unpublished) of the Aegean Sea basin. The fish fauna of the Dragovitica River, 214 which drains South-East Serbia to the Struma (i.e. Strymon) River in Bulgaria, re- mained completely uninvestigated. The long lasting geological isolation of the region from the Danube River drainage (Black Sea basin) by Čemernik, Vardenik, Besna Kobila and Dukat Mountains has resulted in prominent endemism of the fish fauna in the adjacent Struma River drainage (MIHAILOVA 1965, STEFANOV 2001). Therefore, it has been decided to undertake a sampling study between 11 and 14 April 2002, to seek what species occur and to identify their population status, in order to derive the appropriate conservation measures. Study Area The area of investigation that covers about 700 km 2 is situated at the mere south- east of Serbia (Fig. 1), including the Dragovitica River, the only one draining to the Struma River in Bulgaria. The rivers length from the spring of the Dragovitica River to the border of Bulgaria is about 12 km, whereas its length together with one of the tributaries, the Boica River, amounts to about 63 km. The Boica River is formed by several creeks that run southwards on the eastern edge of the Vlasina highland. The Dejan Creek is the longest one of them. The upper section of the Boica River ends at the junction with the Lisina River, at the upper part of the Lisina Reservoir. The largest tributary in that section is the Toplodolka River. Downstream the reservoir the Boica River is much smaller all the way to the junction with the Ljubata River and the spring of the Dragovitica River in the vicinity of the city of Bosilegrad. The last large tributary is the Brankovačka River, which comes from the southern slopes of the Dukat Moun- tain. For each river characteristics see Table 2. Material and Methods The field research was made between 11 and 14 April 2002 using the electrofishing gear made by the Institute for Fisheries, Ljubljana, Slovenia (1.5 KW, 220 V AC trans- formed to the 220 V DC), by depleting the sampling profiles (for length of profile see Table 2) and by using both upstream and downstream stop nets with mesh side size 1 cm (National Marine Fisheries Service, 2000), following the guidelines for handling the endangered species from the national legislative (Ministry of Environment Protection 1995). Each sampling was worked out in repeated passes on each river/stream. Sam- pling sites were chosen to be the best possible representative regarding the character of the water course, comprising the adjacent rapid, the whirlpool and the still flowing section. The measuring tape was used for assessing the length, width and depth of profile. The surface water velocity was measured by standard floats and chronometer and calculated afterwards. The identification of fish was made by keys of MAITLAND (1977) and SIMONOVIĆ (2001), with the additional help from PATRIC BERREBI and PETR KOTLIK (pers. comm.). The names of fish species were used according to the nomenclature of KOTTELAT (1997) and Eschmeyer (http//www.FishBase.org), after taking into account the considerations of CRACRAFT (1987). The data on water characteristics at the first sampling spot on each water course were both spot-measured in the field, using WTW equipment (oxygen meter, pH meter) and analyzed at the laboratory of the Health Care Institute, which is the referent institution in Belgrade, using standard laboratory methods.