According to all empirical equations, the natural mortality (M) of males was higher than that of females.
The M of males ranged between 1.10 and 1.91 y-1and averaged 1.4 ± 0.37 y-1, while that of females ranged between 0.97 and 1.64 y-1 and averaged 1.2 ± 0.32 y-1 (Table 2).