FEEDING ECOLOGY OF PREDATORY FISHES FROM GROOTE-EYLANDT IN THE GULF OF CARPENTARIA, AUSTRALIA, WITH SPECIAL REFERENCE TO PREDATION ON PENAEID PRAWNS

The aim of this study was to describe the feeding ecology of predatory fishes in the inshore waters of Groote Eylandt in the Gulf of Carpent aria, a large tropical bay in northern Australia. This knowledge will increase our understanding of trophic ecology of fishes in tropical wa ters and, in particular, their interactions with commercially importan t penaeid prawns. Several structurally complex habitats, including sea grass beds, mixed seagrass/reef habitats and mangrove areas, which sup port a diverse marine fauna, are found in these shallow waters. Conseq uently the diets of most predatory fishes in the region comprise a wid e variety of fish and invertebrate prey. Juveniles of several species of penaeid live in seagrasses, where they are preyed on by, especially , Scomberoides commersonianus and the common shark species. However, t he impact on juvenile penaeid populations is not as high as in the tro pical estuaries of north-eastern Australia where fish abundances are l ower. Many predatory fishes are size-selective and, in general, larger fish eat bigger penaeids. Seasonal and diel predation on penaeids is largely density-dependent. Evidence from this and previous studies ind icates that individual species of tropical marine fishes eat similar p rey (taxa and proportions) regardless of their habitat; any difference s are chiefly only at the level of genus or species.