The Dietary Compositions of the Blue Swimming Crab, Portunus segnis (Forskal, 1775) from Persian Gulf, South Iran

This investigation was carried out to determine the feeding habits of blue swimming crab, Portunus segnis from around waters Boushehr, Coast of Persian Gulf, South Iran. Sampling was performed trawl net during winter and spring seasons (January 2011 to June 2012) as processed 426 crabs was collection. After freezing, the samples were transferred to the laboratory in order for further analysis. The first, the biometry features (body weight (BW) and carapace width (CW) were measured then the stomach of each sample was surveyed. The results showed that 131 stomachs were filled, 209 of them were semi-filled and 86 of them were empty. During microscopy decomposition, the observed materials and food in the stomachs were classified into 7 groups including crustaceans (46.08 %), Molluscs (19.6%), fishes (23.4%), seaweeds (2.03%), benthos (1.7%), Mixed (4.7 %) and unidentified (2.49%). There was significant differences between the different food items (P<0.05), there was no significant difference between the contents of male and female stomachs (P>0.05). There were significant differences in the preference for food items in the different season (P<0.05). There were also significant differences in the preference for food items in the different size groups of the crab (P<0.05). The vacancy index of stomach (CV) during sampling was 20.02, this finding indicates that this species is an overeater. The result also showed that P. segnis is an omnivorous species and a clear preference for crustaceans.