250 Bulgarian Journal of Agricultural Science, 19 (2) 2013, 250–254 Agricultural Academy DISTRIBUTION OF CRAYFISH AND CRABS IN THE UPPER REACHES OF THE KAMCHIYA RIVER, BULGARIA E. STOYNOV1, D. PARVANOV2 and A. GROZDANOV2 1 Fund for Wild Flora and Fauna, BG – 2700 Blagoevgrad, Bulgaria 2 Sofi a University “St. Kliment Ohridski”, Faculty of Biology, BG – 1164 Sofi a, Bulgaria Abstract STOYNOV, E., D. PARVANOV and A. GROZDANOV, 2013. Distribution of crayfi sh and crabs in the upper reaches of the Kamchiya River, Bulgaria. Bulg. J. Agric. Sci., Supplement 2, 19: 250–254 As a result of this study, twelve new localities were discovered and four indigenous species (noble crayfi sh – Astacus asta- cus, narrow-clawed crayfi sh – Astacus leptodactylus, stone crayfi sh – Austropotamobius torrentium and Potamon ibericum) were found in a relatively small area in the upper reaches of the Kamchiya River – Kotel Mountain (Eastern Stara Planina Mountain, Bulgaria). Extremely rare in Europe mixed populations of A. torrentium and A. astacus were detected in Golyama Kamchiya and Luda Kamchiya Rivers. The ratio of A. torrentium to A. astacus in the total catch decreased considerably from habitats with large stones and high water velocity to sites with small stones and relatively slow velocity for both locations with observed mixed populations. The obtained results are important for the development of management strategies with the aim of better crayfi sh and crab habitat protection in the circumstances of increasing anthropogenic impact. Key words: Astacus astacus, Austropotamobius torrentium, Astacus leptodactylus, Potamon ibericum, mixed populations, Kamchiya River Introduction data about freshwater decapods in Eastern Bulgaria, espe- cially in Eastern Stara Planina Mts. and Kamchiya River There are three species of crayfi sh (Astacus leptodac- is rather scarce. tylus Esch., Astacus astacus L. and Austropotamobius The noble crayfi sh (A. astacus) and the stone cray- torrentium Schrank) and one species of freshwater crab fi sh (A. torrentium) have been included as ‘endangered’ (Potamon ibericum, Bieberstein) in Bulgaria. Their dis- species in the Bulgarian Red List and have been listed tribution was studied from the middle of the last century in the Annex IV of European Community Directives for (Bulgurkov, 1961; Subchev and Stanimirova, 1998). In the Conservation of Natural habitats and wild Flora and recent years, the data has been updated and new locali- Fauna (97/62/EU) as subject of special conservation mea- ties have been found (Subchev, 2001; Hubenova et al., sures. 2002, Bechev, 2000; Bechev, 2004; Zaikov, 2004; Zaikov In producing this paper, the authors aim to provide new and Hubenova, 2007; Zaikov et al., 2010b, c; Zaikov et information about the distribution of crayfi sh and crabs al. 2011a,b). In addition detailed investigations of the re- in Bulgaria. An additional aim of this article is to inform productive biology (Hubenova et al., 2002; Hubenova et and promote the development of appropriate management al., 2010) and shelter competition between different age strategy for the conservation of crabs and crayfi sh habitats groups and species have been made (Zaikov et al., 2001; in the upper reaches of Kamchiya River in relation to the Zaikov et al., 2004; Zaikov et al., 2010a). However, the establishment of Natura 2000 network. *E-mail: [email protected] Distribution of Crayfi sh and Crabs in the Upper Reaches of the Kamchiya River, Bulgaria 251 Material and Methods worm or piece of meat) is moved up and down in front of the crayfi sh hole. The method is also called “thumping” because Between 2004 and 2011, twelve localities on the upper during the crayfi shing the bait frequently touches the bot- reaches of the Kamchiya River were examined periodically tom of the river. During this process, the crayfi sh come out for the presence of freshwater crabs and crayfi sh. The locali- from their shelter, attracted by the bait and its specifi c verti- ties included the main river and most of its major tributaries cal movement and began to look for it. Once the crayfi sh (Golyama Kamchiya, Luda Kamchiya, Kotleshnica, Med- has the bait fi rmly in his claws, the bait is raised to the water venska, Glogova and Neikovska rivers). At each river site, surface (Figure 2). locations for sampling were selected based on ease of access All of the crabs and crayfi sh caught were determined to to the shore and identifi cation of areas believed likely to pro- species (Pöckl et al., 2006; Zaikov, 2010). vide suitable crab and crayfi sh habitat (Figure 1). Crabs and crayfi sh captured were counted and identifi ed. After these Results and Discussion procedures, the individuals were released back to the water. In some locations, local anglers provided additional material. Throughout this research a total number of 837 crayfi sh Three sampling methods were used to catch crabs and (356 – A. astacus, 242 – A. torrentium; 232 – A. leptodacty- crayfi sh: lus) and 129 crabs (P. ibericum) were caught. The presence (1) Direct hand sampling from the river bed, by searching of three crayfi sh species (the noble, the narrow-clawed and spaces between rocks and within the roots the stone crayfi sh) and one crab species (Potamon ibericum, (2) By ring net, which is basically a basket made of two Bieberstein, 1808) have been discovered (Figure 3). During solid rings connected by cotton or nylon 0.6 cm mesh. The the research period twelve of the investigated localities were top ring has a larger diameter (50 cm) than the bottom ring inhabited by certain species, three populated by the stone (30 cm). When deployed, this kind of trap becomes fl at on crayfi sh (Austropotamobius torrentium, Schrank, 1803), the river bottom, giving crabs and crayfi sh access to the bait eight by the noble crayfi sh (Astacus astacus, Linnaeus, in the centre. 1758), two by the narrow-clawed crayfi sh (Astacus leptodac- (3) A new highly effective method with а fi shing rod, tylus, Eschscholtz, 1823) and one by the Potamon ibericum. cord, safety pin and bait attached to it was used. The bait The population of Potamon ibericum in Medvenska (small fi sh (e.g. Phoxinus phoxinus, Linnaeus, 1758), earth- River is the fi rst locality reported in the Kamchiya River Fig. 1. Habitat of noble and stone crayfi sh in Golyama Kamchiya River near Ticha Village Altitude: 400 m Geographic coordinates: 42° 58’23.23”N / Fig. 2. Crayfi shing in Kotleshnica River using 26°23’23.48”E “thumping” method 252 E. Stoynov, D. Parvanov and A. Grozdanov Fig. 3. The distribution of freshwater crayfi sh and crabs in the upper reaches of Kamchiya River Fig. 4. Crayfi sh captured in Golyama Kamchiya River between the villages Bratan and Ticha (13.08.2004) (a) Male noble crayfi sh (Astacus astacus). (b) Male (up) and female (down) stone crayfi sh (Austropotamobius torrentium) Distribution of Crayfi sh and Crabs in the Upper Reaches of the Kamchiya River, Bulgaria 253 Basin. The other populations of this freshwater crab in Bul- torrentium living in the same habitat have been performed. garia were described in Tundja, Maritsa, Arda and Mesta The observed results about the ratio between these two rivers by previous reports (Subchev and Stanimirova, 1998; species showed that A. torrentium is able to exclude larger Bechev, 2004). Potamon ibericum was observed in different specimens of the other crayfi sh from shelter and may show regions from the Black Sea catchment area such as the riv- a generally more aggressive behavior than Astacus astacus. ers in Strandzha Mountain and near Varna. Despite the wide However, it could be assumed that the main factor that was distribution of this species in Bulgaria and the relatively high responsible for the reported larger numbers of A. torrentium number of localities, some of its populations are fragmented, compared with those of A. astacus in specifi c parts of the and the threat level from pollution and climatic changes is studied localities was the size and shape of the river stones. high, so there is cause for concern for the future of some of its populations including the newly discovered one in Med- Conclusion venska River. Mixed populations of A. torrentium and A. astacus were Three indigenous crayfi sh and one crab species were found in Golyama Kamchiya and Luda Kamchiya rivers found in a relatively small area in the upper reaches of the (Figure 4). These localities are the only places, reported in Kamchiya River. In addition, the discovery of mixed popula- Bulgaria, where the latter two species of crayfi sh occur to- tions of A. astacus and A. torrentium in two localities in Ko- gether. Mixed populations of these species were found in tel Mountain is an essential prerequisite for the development other European countries – the Czech Republic (Kozak et of management strategies with the aim of better crayfi sh and al., 2002), Germany (Sint et al., 2006), Croatia (Magiure crab habitat protection in the circumstances of increasing an- and Gottstein-Matocec, 2004) and Romania (Parvulescu thropogenic impact. and Petrescu, 2010). The reason for the rare occurrence of these mixed populations is still not known. The sites where characterized by having both banks of the river shaded by References trees (Figure 1). The species occur on a substrate consisting Bechev, D., 2000. New localities of Potamon fl uviatilis (Herbst) primarily of stone and gravel, the preferred shelter is repre- (Crustacea: Decapoda) in Bulgaria. Travaux Scientifi ques de l’ sented by the spaces under and between stones. The most Universite de Plovdiv Animalia, 36: 95–96. frequent combination of riparian vegetation is. Alnus sp. and Bechev, D., 2004. The freshwater crab (Crustacea: Decapoda: Salix sp. Potamidae) in the Eastern Rhodopes (Bulgaria). – In: Beron The ratio of A.