Trophodynamic Indicators and Trophic level estimation of Nemipterus japonicus (Bloch, 1791) in the northern Oman Sea, Iran

In order to increase the knowledge of Nemipterus japonicus biology and ecology, an investigation of food habits of this species was surveyed seasonally from October 2017 to August 2018 in Oman Sea. In this survey, stomach contents fishes 210 were studied (91 female and 119 male). According, some indexes such as; the feeding intensity index (2.60%), the index is empty stomachs (43.80%), the mean Trophic levels (4.08), and the rate of food consumption (9 per year) was calculated. Total four major taxonomic categories were identified in the stomach contents of this species and were weighted including arthropods (Crustaceans), Cephalopods, Teleostei and Sea weeds and the results show that Arthropods with an abundance of 55.75% was the most abundant prey item. According to the Prey Occurrence Index, the Portunidae (61.19%), Squilla mantis (28.35%) and digested bone fish (20.89%), were divided as the main, the incidental and occasional food, respectively. The results showed that the highest intensity of feeding occurs in winter (50.77%) and the lowest in fall (35.20%). Also N. japonicus shows cannibalistic behavior in ecosystem in winter (3.00%) and in spring (6.00%) respectively. According to the results of this research that has been done for the first time in the northern of Oman Sea, the results of frequency of occurrence of prey showed that N. japonicus is carnivore and also on the basis of the index empty stomachs is the average rate of food consumption this species of fish.