Biological characteristics of Japanese threadfin bream)Nemipterus japonicus(in the coastal waters of Province Bushehr

This study was conducted to determine biological characteristics of threadfin bream (Nemipterus japonicus) in Persian Gulf (Bushehr Province), during November 2006 and October 2007. The minimum and maximum specimens were 75 - 273 mm FL. Based on the power relationship between fork length and weight, slope (b) for individuals was 2.987321. The emptiness value (V) was 45.6% and it shows that N. japonicus is a moderate feeder. The results of Fp indicates that crustacean with 78.2% are main foods, mollusca (27.7%), fishes (20.7%), polychaeta (19.2%) and Foraminifera (11.7%) were identified as minor foods and phytoplanktons (9.9%), nematode (8.0%), echinodermata (2.3%) and sea weeds (0.3%) were random foods. Ultimately, it was found that threadfin bream is a carnivorous species and from point of feeding intensity is a moderate feeder.The overall sex ratio was estimated as M: F =1.0: 2.6.The maximum GSR values were recorded in April and then in September for females and in September and then in April for males. The reproduction studies showed the spawning season extended within 2 peaks, from April- May and September and main spawning occurs in spring season.