Willis, S.; Laurenson, L.; Mitchell, B.; Harrington, D.

Stomach contents of larval and juvenile Acanthopagrus butcheri from an estuary were studied to determine ontogenetic differences in diet. Evidence of ontogenetic differences in diet strongly linked to ontogenetic changes in habitat preferences was identified. Larvae were found to exclusively utilise pelagic habitats while juveniles settled into fringing weed beds in shallow estuarine waters Larvae < 9 mm in length fed primarily on calanoid copcpod nauplii. Larvae >9 mm consumed mainly calanoid copepoditcs and unidentified fish larvae. The most important diet items for juveniles <40 mm in length were calanoid copcpods, particularly Gladioferens pectinatus and Sulcanus conflictus. With increasing size (>20-40 mm to > 40- 60 mm), copepods became less important in the diet and were replaced by amphipods. gastropods and polychaetes. reflecting a shift from feeding in the water column to feeding in weed beds, Polychaetes were the main food types consumed by juveniles >60 mm in length. The diverse range of food types found in stomachs illustrates the flexible and opportunistic nature of feeding in juvenile A. butcheri.

Available for public viewing at: NRE - Heidelberg Library, Arthur Rylah Institute of, Environment Research, 123 Brown St, Heidelberg 3084, DX 211902, Phone: (03) 9450 8604, Fax: (03) 9450 8664, heidelberg.library@nre.vic.gov.au