Diet of poor cod, Trisopterus minutus (Osteichthyes: Gadidae) from the eastern central Adriatic Sea

The diet of poor cod, Trisopterus minutus, from the central Adriatic Sea, was investigated with respect to fish size and seasons. Stomach contents of 1200 specimens, 8.1 to 25.5 cm total length (TL), collected by bottom-trawl from January to December 2006 were analysed. The percentage of empty stomachs varied significantly with season (maximum during the winter, 23%; minimum during the summer, 5%). The prey items identified in the stomachs belong to seven major groups: Decapoda, Mysidacea, Euphausiacca, Stomatopoda, Teleostei, Cephalopoda and Polychaeta. Decapods were the most important ingested preys in all seasons as well as in size from 12.2 to 22.1 cm TL. Mysidacea constituted the main prey for fish Lip to 12.2 cm TL. The proportion of teleosts in stomach contents increased with the increasing size of poor cod and was 56% IRI (index of Relative Importance) in largest size class (> 22.1 cm TL). Three decapods, Alpheus glaber (%IRI = 8.8), Processa canaliculata (%IRI = 6.3) and Pontocaris cataphractus (%IRI = 2.3), followed by teleost, Lesueurigobius friessi (%IRI = 2.1) were the most frequent preys. Diet composition showed little seasonal variation; decapods were the most important prey in all seasons especially during the summer. The lowest intensity of feeding recorded in winter could be related to lower sea temperature and to the spawning period. The stomach contents of the poor cod indicated that this species could be a euryphagous predator.