Basic life-history parameters of the blue swimmer crab Portunus pelagicus (Linnaeus, 1758) along the Gulf of Suez, Red Sea, Egypt

Abstract

The resource managers need to know life-history parameters to understand the biology and population dynamics of the respective species and respond to risks to natural populations and ecosystems. Sixteen life-history traits of the blue swimmer crab Portunus pelagicus along the Gulf of Suez were assigned. P. pelagicus is one of the popular shellfish species that stands out for its higher commercial value and consumer preference. The study revealed that P. pelagicus has tmax equals 3 yrs for males and 2 yrs for females. The overall sex ratio (♂:♀) was 1:0.78. The results do not reject the null hypothesis Ho of a 1:1 ratio of male to female. The average fecundity increased with increasing the CW where it was 407338 (±35529), 617937 (±42086), and 793928 (±37610) eggs per batch for a mean CW of 10.7, 14.6, and 18.1 cm respectively. The estimated CW-Weight equations were W= 0.0175 CW3.277 (R2 = 0.94), W= 0.0242 CW3.273 (R2 = 0.93), and W= 0.0171CW3.276 (R2 = 0.94) for males, females, and combined sexes respectively. The value of b indicated a positive allometric growth (b > 3) for both sexes. The average values of CW∞, K, to and W∞ as well as the computed Ø' values were 23.83 cm, 0.78 yr-1, 0.27 yr, 570.0 g, 2.65 for males, 20.44 cm, 0.93 yr-1, 0.01 yr, 471.0 g, 2.59 for females, and 23.86 cm, 0.89yr-1, 0.02 yr, 557.0 g, 2.70) for combined sexes respectively. The mortality rates were estimated as: Z was 2.44, 3.41, and 2.89 /yr, M was 0.90, 1.17, and 1.09/ yr, F was 1.54, 2.24, and 1.80 /yr), and the estimated E was 0.63, 0.66, and 0.62 for males, females, and combined sexes respectively. Based on these results, a sustainable management program for P. pelagicus in the Gulf of Suez could be proposed.