Age determination, growth indices and reproduction biology of Prussian carp, Carassius gibelio (Bloch, ۱۷۸۲) from four reservoirs in Golestan Province, Southeast Caspian Sea

This study aimed to determine age and growth indices of Prussian carp, Carassius gibelio collected a total of ۹۴۲ specimens on a monthly basis from February through September ۲۰۱۵ in three dam lakes including Golestan, Boostan and Voshmgir and one reservoir named Alakoli from the Southeast Caspian Sea. The largest specimen was a female with ۲۲۰ mm in total length (TL) and ۱۳۹.۷۸۷ g in weight from Voshmgir. The maximum condition factor of the fish increased markedly during late April- August in all areas. Growth pattern was positive allometric in females from Alakoli, while negative allometric in females from Golestan, Boostan and Voshmgir and also in males from Voshmgir. The isometric growth observed in males from Golestan and Boostan as well as from Alakoli. The growth parameters of von Bertalanffy fit to the mean observed total lengths-at-age for each sex separately were estimated as L∞= ۳۷۸.۰۹ mm, K= ۰.۱۲, t۰= -۰.۳۵ for females, L∞= ۳۰۹.۳۸ mm, K= ۰.۱۷, t۰= -۰.۰۲ for males, and as L∞= ۳۵۵.۷۴ mm, K= ۰.۱۳, t۰= -۰.۳۵ for total population in Golestan; L∞= ۲۹۹.۰۶ mm, K= ۰.۱۸, t۰= -۰.۱۰ for females, L∞= ۵۷۴.۱۷ mm, K= ۰.۰۷, t۰= -۱.۰۴ for males, and as L∞= ۳۳۸.۴۳ mm, K= ۰.۱۵, t۰= -۰.۳۴ for total population in Boostan; L∞= ۲۹۶.۳۷ mm, K= ۰.۲۰, t۰= -۰.۲۰ for females, L∞= ۱۸۶.۲۳ mm, K= ۰.۵۱, t۰= -۰.۴۲ for males, and as L∞= ۳۰۲.۹۴ mm, K= ۰.۱۹, t۰= -۰.۱۸ for total population in Voshmgir; and L∞= ۳۴۷.۹۹ mm, K= ۰.۰۴, t۰= -۰.۱۲ for females, L∞= ۵۳۰.۹۲ mm, K= ۰.۰۱, t۰= -۰.۱۸ for males, and as L∞= ۴۷۷.۷۳ mm, K= ۰.۰۱, t۰= -۰.۴۰ for total population in Alakoli. A prolonged spawning period was observed from April through August. Maximum egg diameter and absolute fecundity were ۱.۳۹ mm and ۷۲۸۶۵ oocytes in population inhabiting Voshmgir respectively.

Keywords:

Carassius gibelio , Length-Weight Relationship , VBGF , Reproduction , Southeast Caspian Sea