Feeding biology of Caranx bucculentus Alleyne and Maclay (Teleostei: Carangidae) in Albatross Bay, Gulf of Carpentaria, with special reference to predation on penaeid prawns

Caranx bucculentus is an abundant predator in the commercial prawn grounds of Albatross Bay in the Gulf of Carpentaria. The stomachs of samples taken from Albatross Bay contained mainly teleosts (48%) and crustaceans (46%), with commercially important prawns contributing 15% by dry weight to the total diet. The proportion of teleosts, penaeids, brachyurans, 'other crustaceans' and molluscs in the diet changes as the fish grow and their diet shifts from mainly crustaceans to mainly teleosts. Although the percentage of teleosts, penaeids, brachyurans and 'other crustaceans' eaten varied with the time of sampling, no seasonal variation was noted. Only the numbers of penaeids and 'other crustaceans' eaten varied significantly over 24 h. Caranx bucculentus less than 200 mm SL ate most penaeid prey during the day and primarily took small, commercially unimportant species. In contrast, fishes more than 275 mm long took larger, commercially important species, and mainly at night. The abundance of large C. bucculentus and the high incidence of commercial penaeids in their diet indicate that this species may have a considerable impact on the prawn resources of Albatross Bay.