A comparative study of the fecundity in Chondrostoma regium and Chondrostoma cyri (Leuciscidae) in Gamasiab and Aras Rivers

Chondrostoma regium and Chondrostoma cyri belong to the genus Chondrostoma, which are distributed in the Tigris, Isfahan, Kor and Caspian Sea basin and have ecological and sport fishing importance. The main purpose of this study was to investigate the relationship between the fecundity with length, weight and age of the fish species in Gamasiab from Tigris and Aras River and fish sampling was performed in December and March 2008 using cast-net and electro-shocker. The result of the study on 46 female fish in maturity stages 4 and 5 (the previous stages to prepare for spawning) in C. regium showed that the absolute fecundity of 1694 to 10843 (5252.7±2377.1) eggs and the relative fecundity of 58 to 154.2 with an average of 98.9 eggs per grams of female weight. Also, the results of 31 fish samples showed C. cyri absolute fecundity of 5526 to 18145 (11135±3284.6) eggs and the relative fecundity of 84.8 to 162.0 with an average of 113.8 eggs per grams of female weight. Also, the correlation (r2) between absolute fecundity and weight, total length and age was .27, .37 and .17, respectively for C. regium and 0.714, 0.702 and 0.712 were determined for C. cyri. The egg diameter of this species was 0.80- 1.96 with an average of (1.22±.29), Also, for C. cyri, the range was 0.78 to 2.25 with an average of 1.44±0.29 mm.