Fecundity in migratory kutum, Rutilus frisii (Nordmann, 1840) in Sefid River and its relationship with weight, length and age

This study aimed to determine fecundity in relation to age and size, and the correlation between fecundity and egg diameter with whole body weight, total length and age in migratory kutum, Rutilus frisii, to Sefid River, southern Caspian Sea. Ripe females were caught about 1000 m far from the river mouth using beach seine with 20 mm mesh size during their migration season in March 2021, and they were transferred into ponds of Shahid Ansar propagation and restoration center for bony fishes of Caspian Sea, Rasht city. The propagation of females was done using hormonthrapy (Ovaprim). The total length, body weight, and age of specimens were measured before artificial propagation and the weight of the gonad was measured. One gram of egg was sampled randomly and fixed into a glass containing formaldehyde 5%. Then the precise weight of the egg samples was determined using a digital scale. The examination of 98 female specimens with a weight 540-2710g (1231±384, Mean±SD) showed that working fecundity of 23577-92029 (49643±16185) eggs per individual, relative fecundity of 25.4-58.1 (40.7±6.8) eggs per gr / body weight and eggs diameter of 1.67-1.99 (1.84±0.06) mm. The working fecundity was raised with increasing fish age and size but relative fecundity decreased by increasing age and size.