Feeding behaviour and daily ration of the spotted flounder Citharus linguatula (Osteichthyes: Pleuronectiformes) in the central Tyrrhenian Sea

Abstract

Spotted flounder Citharus linguatula (Linnaeus, 1758) is one of the most abundant species within demersal fish assemblages next to the continental shelf (up to 200 m depth) of the Mediterranean Sea. In spite of the ecological importance of this species in the central Tyrrhenian Sea, many aspects of its biology (e.g. feeding behaviour) are poorly described. In order to analyze how feeding habits are related to the ontogenetic changes in this species, 2636 specimens (between 9 and 26 cm of total length TL) were collected from November 2000 to January 2002. During ontogenetic development spotted flounder occupied different trophic levels: diet shifted from mysids, predominantly in the smaller spotted flounder ( 19 cm TL). Before the transition to the icthyophagous phase, a more generalist foraging behaviour including decapods (Processa sp., Alpheus glaber), molluscs (Turitella sp.) and benthic fish (Lesuerigobius spp., Gobius niger, Callionymus spp., Arnoglossus laterna) dominated the diet. Seasonal analysis of the diet showed an increase in the presence of mysids in summer and autumn, and of decapods in summer and spring. Teleosteans are present throughout the year without significant variations. Daily ration values, computed from the Eggers method, ranged from 1.57% to 2.83% wet body weight, showing a negative relationship between reproduction and daily consumption rate.

Keywords

• spotted flounder
• feeding
• mediterranean sea
• ontogenesis
• pleuronectiformes.