Life history traits and fishing mortality estimations of Caspian vimba, Vimba vimba (L.), in southwestern coastal regions of the Caspian Sea

Abstract

This study was conducted to complement existing data about the life cycle of Caspian vimba, Vimba vimba (L.), with estimations of age, growth, and mortality rates. To achieve this, 811 specimens were collected between May 2012 and June 2013 at three fisheries catch stations in southwestern regions of the Caspian Sea including Talesh, Bandar Anzali, and Kiashahr. The growth rate in vimba is relatively high at approximately 0.29 year-1 for females and 0.32 year-1 for males. Asymptotic lengths are 245 mm and 233 mm for females and males, respectively. The growth pattern was isometric for both males and females. The overall sex ratio was balanced (1: 0.92). The instantaneous coefficients of total, natural, and fishing mortality were 1.27, 0.4, and 0.8 year, respectively, and the current exploitation ratio was 0.63 year-1. Results showed that the growth rate of males is higher than that of females. Considering the exploitation ratio, it is apparent that the vimba population is experiencing significant legal and illegal exploitation pressure.