Growth and reproduction of Cyprinion macrostomus (Heckel, 1843) and Cyprinion kais (Heckel, 1843) populations in Karakaya Dam Lake (Euphrates River), Turkey

This study investigated the age–length relationship, length–weight relationship, somatic condition, gonadosomatic index, and reproduction properties of Cyprinion macrostomus and Cyprinion kais. C. kais is an endemic species included on the IUCN Red List of Threatened Species in the Tigris–Euphrates Basin. A total of 153 C. macrostomus and 114 C. kais were collected. The estimated length– weight relationships were W = 0.725 × FL^2.92 (r^2 = 0.87) for C. macrostomus and W = 0.417 × FL^3.02 (r^2 = 0.93) for C. kais. The age–length relationships were L_t = 15.0 [1 – e^–0.212 (t + 0.407)] and L_t = 15.4 [1 – e^–0.205 (t + 0.503)] for C. macrostomus and C. kais, respectively. Mean fecundity ranged from 313 to 1647.08 eggs/fish for C. macrostomus and from 295.1 to 1255.2 eggs/fish for C. kais. Mean oocyte diameter ranged between 0.13 and 1.34 mm for C. macrostomus and between 0.14 and 0.86 mm for C. kais. Based on gonadosomatic index, the spawning periods of C. macrostomus and C. kais were determined to be between June and August in the area of the study.