Age and growth of kutum (Rutilus frisii kutum, Kamensky, 1901) in southern Caspian Sea

Age and growth of the Caspian kutum, Rutilus frisii kutum were studied in the southern Caspian Sea from early October 2006 to the middle of April 2007. Fork length and weight ranged from 21 to 58 cm and weights from 104 g to 2450 g, respectively. The largest length-groups was observed in December and the lowest in April, which was coincided with feeding and spawning periods, respectively. There was a significant difference from 1 : 1 overall sex ratio. Age determination, based on scale readings, showed that the population was composed of nine age- groups. The Caspian kutum grew isometrically and rapidly during the third year. In both sexes, specimens were maximally 4 years old. In older individuals, condition cycle was related to the gonad development and showed some differences between sexes. Age-at-length data were used to determine von Bertalanffy growth parameters for this population for both sexes indicating that K value of males was more than that of females. Growth performance index (ǿ) was 2.89 for all individuals. The results showed that R. f. kutum is a rapidly-growing species in the southern Caspian Sea.