Feeding indices for Indo-pacific swimming crab, Charybdis hellerii (A.Milne-edwards, 1867) in coastal waters of the Persian Gulf (Hormozgan Province)

Feeding habits studies are one of the most important subjects in fisheries science. The investigation on feeding habits of true crabs is one of the most significant factors in the study of the growth and survival of crabs. The distribution, growth, and reproduction of crabs are all largely dependent on the availability of prey. The feeding habits of the Indo-pacific swimming crab, Charybdis hellerii (A. Milne-Edwards, 1867) were studied in the northern Persian Gulf during the period from June 2015 to May 2016. Sampling was conducted along coastal waters by monitoring bottom shrimp trawlers. A total of 371 stomachs were measured of which 197 were full and 174 were empty. Crabs stomach contents included: 60.75% crustaceans, 11.5% fish, 8.6% molluscs, 6.1% seagrass, 5.3% mixed, and 7.7% undetectable and non-food as sand and gravel. The gut vacuity index was 46.9% during the research which showed medium nutriment in this animal. Crustaceans, fish and molluscs were the dominant main food in gut. The results indicated that gut vacuity index was not statistically different between crab with barnacles and crabs without barnacles (P> 0.05). The recorded results showed that this species is omnivorous and its diet is medium. There were no significant differences in the preference for food items between the different sexes of crabs. The Indo-pacific swimming crab, as are other portunid crabs, are carnivores with a preference for animal food and the behavior of active predators of sessile and slow-moving macro-invertebrates.