Feeding habits of stargazer (Uranoscopus scaber Linnaeus, 1758) in the southern Adriatic Sea (Croatia)

Abstract

The feeding habits of the stargazer Uranoscopus scaber Linnaeus, 1758 were analysed using 360 stomachs of specimens collected in southern Adriatic Sea between October 2011 and September 2012. The total body length of the specimens ranged from 9.7 to 32.1 cm (18.89 ± 3.34 cm) and weight from 11.7 to 618.7 g (112.79 ± 63.17 g). In the sampled population there were 213 females (59.17%) and 147 males (40.83%). Stargazer is carnivorous fish and its diet in Adriatic Sea was composed of teleost fish, cephalopods and crustaceans. According to numerical abundance fish predominated followed by crustaceans, while according to the gravimetric composition fish predominated followed by cephalopods. Teleost fish were dominant prey in all seasons, and the principal prey were hake Merluccius merluccius and argentine Argentina sphyraena. Argentine was primary food in summer (IRI = 61.63), while hake occur in other seasons. In relation to the total body length teleost fish dominated in diet of stargazer whose total body length was < 25 cm. In size group I and II (TL < 20 cm) A. sphyraena was the main food, while M. merluccius was dominant prey in the size group III (TL = 20 – 25 cm). Vacuity index in the sampled population was relatively low (%V = 11.11%). During seasons the percentage of empty stomachs varied significantly with the highest value in winter (%V = 15.55%) and the lowest in spring (%V = 7.78%). In relation to the total body length the highest vacuity index was recorded for size group II (%V = 5.83) and the lowest for group VI (%V = 0).