The Investigation on Reproduction Characteristics of Crayfish (Astacus leptodactylus Eschscholtz, 1823) in the Keban Dam Lake

This study was carried out to determine the reproduction characteristics of crayfish (Astacus leptodactylus Eschscholtz, 1823) living in the Keban Dam Lake. The research was conducted with total of 8745 crayfish collected during study. The minimum size of female carrying eggs on the pleopods was recorded as 77.05 total length and 10.46 weight The mean number of eggs per unit individual mean weight and mean diameter of eggs as well as mean number per unit live weight were calculated as 129.73, 0.0133:|:0.000 g, 2.94i0.007 mm and .55d:1 .86 ind/g, respectively, in total of 382. linear relationship was found between total length, weight and number of eggs. The strongest relationship appeared to be between the number of eggs and live weight (F=l4.268+4.89W, r=0.682). From the observations of hardened spermatopho reremainings around the seminal receptacle, it was understood that matings started in the second week of January when water temperature was around 8.5 oC. The pleopodal eggs appeared in the third week of January when water temperature was still 8.5 °C. The hatchlings emerged in the 4th week of May (—at 19.5 °C) and the juveniles leaved from spawners in the third week ofJune.