Feeding ecology of the temperate marine fish Achoerodus viridis (Labridae): Size, seasonal and site-specific differences

Abstract

Fish were collected from localities in the Sydney region, New South Wales, Australia, from March 1991 to September 1993. Achoerodus viridis is a benthic carnivore and consumes a wide variety of prey items. Size-specific differences in diet were found. The diet of recruits (17-26 mm SL) collected in seagrass environments was dominated by tanaids, whereas that of rocky reef recruits was dominated by harpacticoid copepods. The diet of rocky reef fish then shifted to gammarid amphipods and other crustaceans (fish 50-150 mm SL) and to mussels and urchins (fish >300 mm SL). Juvenile fish on rocky reefs (450 mm SL) foraged in shallow fringing habitat, whereas adult fish (>200 mm SL) foraged in deeper turf and barrens habitats, reflecting the depth distribution of the species. Feeding rate of larger fish tended to be less than that of smaller fish. Variations in diet and feeding rate were also detected over the year but the patterns were not consistent between years. Among sites, there were differences in diet but these were not related to the position of sites inside an estuary or on the open coast. The results of this study provide information on the feeding ecology of a large labrid fish; this information will aid in understanding the population dynamics of the species.