Evaluation of some feeding indices of Pomadasys kaakan in the Northern Persian Gulf

In this paper the Vacuity Index (VI), Fullness Index (FI) and Food Preference Index (FPI) for the stomach contents of Pomadasys kaakan were evaluated to assess the quantity and kind of food which this fish consumes in the Persian Gulf. A total of 227 specimens were collected from fishing trawlers or landings from November 2005 to September 2006. 24.7% of stomachs were full, 11.9% were semi-full and 63.4% were empty. The seasonal average of VI was 77.4, 44.6, 80.0 and 54.0 % for autumn, winter, spring and summer, respectively. The overall FI was 36.6 with seasonal averages of 22.6, 55.4, 20.0 and 46.0 in autumn, winter, spring and summer, respectively. The main stomach contents were crustaceans (esp. crab & shrimp), fish, mollusks (bivalves, gastropods and cuttlefish), stomatopoda, brittle stars, Lingula sp. and sea weeds. The estimated FPIs for crustaceans were 77.7, fish 32.1, mollusks 28.6 and echinoderms 18.8 %. Overall, the results show that this fish is a relatively frugal species which consumes crustaceans as main food and has adopted itself with ecological changes of the Persian Gulf.