Size at Maturity, Sex Ratio and Variant Morphometrics of Blue SwimmingCrab Portunus segnis (Forskal, 1775) from Boushehr Coast (Persian Gulf)

Abstract

Size at maturity, sex ratio and variant morphometrics of blue swimming crab Portunus segnis was studied for one year along the Persian Gulf coasts, Iran. Sex ratio during a year of study was M:F=0.92:1 which should be the relative frequency of females. Male blue crabs have a V-shaped abdomen and female have an abdomen broad and rounded. The carapace width/length- weight relationship was studied in both sexes of crab. The allometric relationships between the characters of this set suggest that most relationships are positive and highly significant. An analysis of covariance indicates that there is a significant difference between sexes with respect to the carapace width-weight relationship. The crab’s carapace widths ranged were from 75 to175 mm for males and 70 to170 mm for females. The crab’s carapace lengths were from 35 to 80 mm for male and 30 to 80 mm for female. The results of this study show that at the same size, weight and the parameters of carapace length and carapace width male of Portunus segnis are higher than females in Persian Gulf coasts.