Population Biology and Diet of the Pompano Trachinotus carolinus (Perciformes: Carangidae) in Caraguatatuba Bay, Southeastern Brazil

This study evaluated the spatio-temporal distribution, population biology, and diet of the pompano Trachinotus carolinus in Caraguatatuba Bay. Samples were taken monthly from August 2003 through October 2004, by trawling in two previously selected areas (South and North). The North area is more exposed to wave activity and is influenced by a river, functioning as a small estuary. In contrast, the South area is relatively sheltered from wave energy and influenced to a lesser degree by smaller rivers. The fish were measured for length, and the sex and reproductive stage identified. The abundance of pompano was compared between areas and among months. The diet was identified and quantified.T. carolinus showed a very irregular temporal distribution during the study period, with 90.5% of the individuals occurring during the summer (December to March).The population wasdominated by immature individuals. In the diet of pompano, seven items were identified (bivalve shell fragments, crustacean fragments, fish fragments, gastropoda, Mysida, nematode and Tivela mactroides).The bivalve fragments were also attributed to T. mactroides, but the whole and fragmented shells were considered separately, evidencing a very peculiar form of consumption. Fragmented bivalve shells were the most frequent item (96.7%) in the tracts. The second most frequent item was Mysida, present in 10.5% of the digestive tracts. In terms of volume, bivalve shell fragments comprised 91.9% of the ingested items, against 6.4% for Mysida. These results demonstrate that T. carolinus is a carnivorous species, consuming almost exclusively T. mactroides. The population of this species in the Caraguatatuba Bay is dominated by juveniles, and is occasionally found in higher abundance in December and March (end of spring and summer)