Distribution of crayfish and crabs in the upper reaches of the Kamchiya River, Bulgaria

摘要: As a result of this study, twelve new localities were discovered and four indigenous species (noble crayfish–Astacus astacus, narrow-clawed crayfish–Astacus leptodactylus, stone crayfish–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 crayfish and crab habitat protection in the circumstances of increasing anthropogenic impact.