Critical lengths, mortality rates and relative yield per recruit of the common sole Solea solea from the Egyptian Mediterranean coast off Alexandria

Mortality rates of the common sole Solea solea from Alexandria were estimated based on the von Bertalanffy growth parameters obtained by the same authors as L∞ = 34.77cm; K= 0.55 year^−1 and t0 = 0.07 years for males, L∞ = 36.24 cm; K= 0.63 year^−1, t0 = -0.01 years for females and L∞ =35.1 cm; K= 0.58 year^−1 and t0 = 0.003 years for sexes combined during two fishing seasons (2011-2013). The total, natural and fishing mortalities were 2.09, 0.52 and 1.57 year^−1 respectively for males, 1.75, 0.53 and 1.22 year^−1 respectively for females and 1.7, 0.52 and 1.18 year^−1 respectively for sexes combined. Correspondingly, the exploitation ratio was E = 0.75, 0.7 and 0.69/y for males, females and sexes combined respectively. The estimated length at first capture Lc was 15.97, 12.72 and 14.22 cm for males, females and sexes combined, respectively while the length at first maturity Lm was 15.31, 15.87 and 15.98 cm for males, females and sexes combined, respectively. These results reflect the high level of the exploitation. The relative yield per recruit analysis showed that the stock of S. solea is over exploited and needs urgent management regulations to conserve this potential fishery.