The distribution of crayfish (Decapoda: Astacidae, Cambaridae) population in Cris and Mures rivers crossing the Romanian-Hungarian border

The crayfish (Decapoda) fauna of the Mures/Maros, Crisul Repede/Sebes-K r s, CrisulNegru/Fekete-K r s and Crisul Alb/Fehér-K r s rivers was surveyed in 16 sampling areas in 2012. Thecrayfish assemblages of the sampling areas were sampled using LiNi traps, hand collection and electricfishing. A total of 56 individuals of 3 crayfish species, two indigenous (Astacus astacus, Astacusleptodactylus) and one exotic (Orconectes limosus), were registered in the four rivers. The individuals ofthe spiny-cheek crayfish were caught in the K r sladány section of the Sebes-K r s river, making thissite the easternmost border of the current Hungarian range of the species. The extremely rapidcolonization in the Tisza watershed questions the hypothesis that the species has spread to the Tiszafrom the Danube. It was probably introduced into the eastern part of the country accidentally during fishstocking events or intentionally, as a live bait.