Status of Freshwater Crayfish Distribution in Thrace Region of Turkey

This review focuses on the present distribution of two crayfish species: narrow-clawed crayfish Astacus leptodactylus Eschscholtz and stone crayfish Austropotamobius torrentium (Schrank, 1803) in Thrace region of Turkey. The only known native (indigenous) freshwater crayfish species of Turkey is A. leptodactylus. It is found at more sites than A. torrentium. On the other hand, A. torrentium is only found in Thrace region of Turkey. The first population of A. torrentium was observed in Velika River in 1995. In 2006, the second population of A. torrentium was found in Madara Brook in the region, but the abundance of A. torrentium in Madara Brook was very low in comparison to Velika River. Moreover, further studies carried out in some water resources near the population of A. torrentium, such as De[vgrave]irmen Brook, Poyralı Brook, and Hasköy Brook confirmed that no other populations of this species are present in the region at present. Therefore, it can be concluded that A. torrentium is only present in the northwest of Marmara river basin (Istaranca Mountain Part) and A. leptodactylus is widely distributed throughout the places located to the south of Marmara river basin, and Istaranca Mountain might be a border line that separates A. leptodactylus and A. torrentium populations. Moreover, except the presence of these two species, no other crayfish species are found in the Thrace region of Turkey at present.