Some population characteristics of astacus leptodactylus (Eschscholtz, 1823) caught from Keban catching area in Keban Dam Lake and effect of placing hides into the natural habitat on crayfish harvest

In the present study, some population characteristics of Astacus leptodactylus caught from Keban Catching Area in Keban Dam Lake and effect of placing hides into the natural habitat on crayfish harvest were investigated. This study was carried out between January 2005 and December 2006.It was observed that the catch constituted of 2591 crayfish (987 females, 38.09%; 1604 males, 61.91%), and the ratio of females to males was 0.62/1.00. The mean carapace length was measured as 47.60±6.55 mm for females and 52.35±8.56 mm for males. In addition, the mean weight of males and females was 42.74±21.79 g and 27.77±10.26 g respectively. The regression analysis of length-weight was LogW=-3.695+3.0755LogCL for males, LogW=-2.7761+2.5046LogCL for females, and LogW=-3.5041+2.9529LogCL for both sex. A linear relation was found in the carapace length and body weight for females and males (R?2= 0,93, R?2= 0,91, R??2= 0,92). This study showed that males of A. leptodactylus had positive allometric growth gaining, but females of A. leptodactylus had negative allometric growth gaining.The placing of hides into the crayfish habitat caused an impact on the number of caught crayfish, sex ratio and size of crayfish. On the other hand, in 2006, the harvest ratio in no hides placed areas was lower in comparison to the hides placed areas. In the present study, it was observed that the length of sexually mature female was 74 mm total length (36 mm carapace length, 13.5 g), and the length of sexually mature male was 73 mm total length (35 mm carapace length, 14 g).Reproduction season started in the second week of December at 8 ºC water temperature, and females had pleopodal eggs in the first week of January at 8-9 ºC water temperature. First stage juveniles occurred in the third week of March at 18-20 ºC water temperature. The mean pleopodal egg number of females was 181.90±45.6 and the mean weight of pleopodal egg was 0.014±0.002 g. Mean total meat yield was 9.59±4.41 g for males and 6.63±2.27 g for females. This difference was significant (p<0.001). Total meat yield was 20.55% of the body weight in males and 19.99% of the body weight in females.In conclusion, it is thought that exploitation of A. leptodactylus living in Keban Catching Area in Keban Dam Lake can be improved by professional support and management strategies. In addition, it is also thought that management of crayfish population will provide the sustainable use of the area in which crayfish are in for fisheries.