FEEDING-HABITS OF YOUNG-OF-THE-YEAR GREATER AMBERJACK SERIOLA DUMERILI (RISSO, 1810) ALONG THE N/W SICILIAN COAST

Abstract

A survey was carried out from July to December 1992 in the Gulf of Castellammare (N/W Sicily) in order to study the feeding habits of juveniles of the greater amberjack Seriola dumerili. Stomach content analysis showed three different phases of predation during this period, depending on the size variation of the specimens. Cluster analysis suggested prey choice differed within three size groups. Class I (individuals up to 80 mm SL) feed mainly on the zooplankton community (Copepoda and Crustacea larvae). Class II (individuals ranging from 80 to 120 mm SL) represent a transition stage in which fish continue to feed on zooplankton, but benthic and nectonic items also become important. Class III (individuals greater than 120 SL mm) feed mainly on nectonic and nectobenthic items. Fish belonging to the size class II showed the highest value of niche breadth. The role of the Cymodocea nodosa system is stressed as an energy supply of invertebrate and vertebrate food items, especially to the size class II, in which fish shift from a planktivorous to a piscivorous diet. Further research is needed to understand better the feeding rhythm, food consumption and the role of benthic communities in the diet of this species.