Determination of growth parameters and population structures of the Caspian Vimba (Vimba persa Pallas, 1814) in the south-western Caspian Sea

The growth parameters and population traits of the Caspian Vimba were studied in order to investigate the changes in the population structure of this species based on 227 samples which was taken from Kiashahr port, on the southwestern coasts of the Caspian Sea from February 2019 to April 2020. In females, fork length ranged from 13.5 to 20 cm and in males it ranged from 12.5 to 20 cm. The highest frequency in age groups was belonged to 3+ years for both sexes and the sex ratio of male to female was 1: 1.4. The von Bertalanffy growth parameters were estimated as k=0.73, L∞=17.44 cm and t0= -1.4 for females and k= 0.6, L∞=16.97 cm and t0=-1.5 for males. The length-weight relationship showed negative allometric growth patterns for both sexes, and the mean values of condition factor were calculated 1.38±0.01 and 1.35±0.01 for females and males, respectively. The size at the first maturity was estimated 12.5 cm for females and 13.2 cm for males. In conclusion, by comparing the obtained population traits of the Caspian vimba in the present study with the other studies in recent years, indicated a decrease in length range and following that it can be said that this species is under pressure and emphasize the need to reconsideration of fishing management in order to preserve the valuable Caspian vimba stocks.