Investigation on noble crayfish Astacus astacus (Linnaeus, 1758) population in River Razhdavets (Balkan Mountain, Bulgaria)

This article points out the results of the conducted investigation on the noble crayfish population in Razhdavets River (Balkan mountain, Bulgaria). The number of caught crayfish shows relatively high density of the population (CPUE = 2.65). A predominance of the individuals with body weight between 20.1 and 30.0 g was established. They form 27 % of the total catch. The lowest share have the groups with body weight 70.1 – 80.0 g (2 %) and this over 80 g (2 %). The mean body weight of the crayfish was 31.34 g (39.29 g for the males and 25.12 g for the females) with total length 9.01 cm (9.42 cm for the males and 8.68 cm for the females).