Age, Growth, and Gonadosomatic Index (GSI) of Mediterranean Horse Mackerel (Trachurus mediterraneus Steindachner, 1868) in the Eastern Black Sea

The aim of this study was to calculate the basic population parameters of Trachurus mediterraneus off the coast of the Eastern Black Sea. Average total length was estimated as 13.52 ± 1.884 cm for the entire population, 13.08 ± 1.594 cm for males, and 13.62 ± 1.804 for females. Average weight was 20.27 ± 8.819 g for the entire population, 18.65 ± 7.626 g for males, and 21.31 ± 9.184 g for females. Age of the fish ranged between 0 and 5 years. Length-weight, age-length, and age-weight relationships were estimated for the population, where W = 0.0089 × L^{2.9552}; L_t = 26.09 (1 - e{-0.125(t + 4.002)}); and W_t = 136.56 (1 - e{-0.125(t + 4.002)}). Total mortality rates were Z = 3.73 year^{-1} and M = 0.29 year^{-1} for natural deaths, and F = 3.44 year^{-1} for fishing mortality.