Feeding Habits of Predatory Thermophilic Fish Species and Species with Subtropical Affinity from Recently Extended Distributional Range in Northeast Adriatic Sea, Croatia

The study investigates feeding habits of thermophilic species and species with subtropical affinity in the fishing catch in the Bay of Medulin (northeastern Adriatic Sea), and contributes to the knowledge about their presence in recently extended distributional range. In our methodology, the presence of the Seriola dumerili, Sphyraena sphyraena, Lichia amia, Coryphaena hippurus, Caranx crysos, Pomatomus saltatrix, and incidence of Trachinotus ovatus is recorded. A total of 220 specimens are captured during 2017, 2018 and 2019. A dietary assessment is performed, and the index of relative importance IRI was calculated for each prey category. Diet overlap is calculated using Schoener's index, based on IRI. The principal diet of C. hippurus included Sardina pilchardus and Loligo vulgaris. Pomatomus saltatrix consumed species from the Sparidae family and T. ovatus crustaceans from the Mysidacea family. Different species from genus Atherina are represented important foods for L. amia, S. dumerili and S. sphyraena. Diets of significant importance for L. amia included fishes from the family Sparidae, for S. sphyraena from the Carangidae family, and S. dumerili from the Clupeidae and Muliidae families. Our analysis of diet overlap is based on IRI suggests no diet overlap between analysed fish species from Medulin Bay, and that these species utilise differing trophic niches.