Feeding habits of the flounder Paralichthys orbignyanus (Valenciennes, 1842) in a shallow coastal lagoon of the southern Atlantic Ocean: Rocha, Uruguay

Abstract

 A total of 293 stomachs of adult flounders, Paralichthys orbignyanus, were analyzed from the catch of artisanal fisheries that operate in Rocha Lagoon, Uruguay. Flounders between 25 and 64 cm total length showed that 119 individuals (40.61%) had content in their stomachs, the silverside Odontesthes argentinensis being the main prey item. Significant variations were observed between size classes. Cannibalism was less than 3% of total prey items and occurred within the 46–56 cm size class. Significant and positive trends were observed between the length of the silverside and the total length of the flounder, but a low percentage of the variability in prey size (<47%) was explained by the predator size. The specialized and selective diet of P. orbignyanus adults is considered to be typical of active piscivore predators and visual fish feeders. The state of prey digestion (in relatively fresh condition or in the beginning of digestion), the moment of catch and the low feeding index could indicate that the species acts as an active predator during the night.