Distribution Based on Depth of Turkish Crayfish (Astacus leptodactylus Eschscholtz, 1823) in the Keban Dam Lake
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Introduction: The crayfish aren’t Keban Dam Lake’s native species. They have been stocked by human hand in 1980’s and commercial crayfish catching was initiated in 1994. It is important for developing a fishing strategy that the data about distribution based on the depth of crayfish is obtained. Material and Methods: This study was carried out in the Çemişgezek fishing area of Keban Dam Lake in July 2012. In the research, it was used a total of 100 crayfish fykenets, which used prevalently in the region, with D form and 36 mm stretched mesh size, structured with five hoops and a barrier. The fyke-nets were set up from 6m to 36m depths and were kept during four days. The bathometer in the research boat was used for fyke-nets were set up to intended depts. A total of four fishing operations were conducted. The crayfish enclosed in fish ponds were soaked in 40, 50, and 75m deeps for the determination whether they will affect from water pressure. Results: In the fishing trials, a total of 1038 specimens, 56% (585 ind.), 22% (232 ind.), 14% (141 ind.), 5% (52 ind.), 2% (23 ind.), and 1% (7 ind.) of them between 6-10m, 11- 15m, 16-20m, 21-25m, 26-30m, and 31-36m depths, respectively, were caught. In the zones with shallower than 7 meters and deeper than 32 meters, crayfish wasn’t caught by fyke-nets. In the examination occurred on fish ponds, any crayfish soaked on 40m deeps didn’t die, although three of them changed the shell. The mortality ratio was determined to be 6% and 10% for 50m and 75m, respectively. All crayfish changed the shell in 75m deeps was died by water pressure. Discussion: The natural habitat of A. leptodactylus generally is shallow lakes. It was afterwards stocked in the Keban Dam Lake. It is a subject that should be known at what depths it is distributed in the Keban Dam Lake, which has a maximum depth of 210m. The commercial crayfish catching in the Keban Dam Lake has been occurred in between 8-25m depths. When the results of this study are evaluated, it has come to the conclusion that the crayfish may spread all over the dam lake via only human hand.