Age determination and feeding habits of Nemipterus japonicus (Bloch, ۱۷۹۱) in the northern Oman Sea

Age determination and feeding habits of the Japanese threadfin bream, Nemipterus japonicus, was carried out in the northern Oman Sea (Chabahar area), based on ۲۱۲ specimens collected between September ۲۰۰۹ and May ۲۰۱۰. The minimum and maximum fork length and body weight were measured as ۱۴۵, ۲۵۸ mm and ۵۵.۳۱, ۲۸۸.۱۲ g. The relationship between Body Weight (BW) and Fork Length (FL) for all individuals was estimated as BW= ۰.۰۰۰۱×FL۲.۸۳ (r۲ = ۰.۹۴۲۵, n= ۲۱۲). The Vacuity Index (VI) was ۵۵.۲% that shows N. japonicus is a moderate feeder. The maximum and minimum Gastro-Somatic Index for males was in autumn and winter seasons and for females were in summer and spring. The Food Preference Indices were estimated as: crustacean (۶۳.۲%) as main food fishes (۳۸.۹%) and molluscs (۳۶.۸%) as minor food. Age determination was done by otolith sectioning. A total of ۱۳۵ sagitta were sectioned. The maximum age was ۵+ years old for a female with FL= ۲۵۶ mm and the youngest one was ۱ year old for a female with FL= ۱۴۵ mm. Based on obtained results there is a significant relationship between feeding and age namely with increase of age, the feeding rate is decreased without any changes in type of feeding and food contents.