Assessing the trophic ecology and ecological role of small and medium pelagic fish in the Mediterranean Sea; insights from diet studies, isotopic data and food-web models

Abstract

The 3rd CLIOTOP Symposium,14-18 September 2015, San Sebastian, SpainSmall and Medium Pelagic Fish (SMPF) such as, clupeids, horse mackerels and mackerels, have been described as key species in the functioning of marine ecosystems. Moreover, they support important fisheries worldwide. Accurate knowledge of their feeding ecology and ecological role is necessary in order to develop realistic quantitative assessments and to exploit and manage these species in a sustainable way. In this review, we synthesize all available information concerning the feeding habits, ecological role and potential predators of seven commercially and ecologically important species of SMPF (Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Trachurus trachurus, T. mediterraneus, Scomber scombrus, S. colias) in the Mediterranean Sea. Specifically, information gathered from stomach content analyses, stable isotope analyses and ecosystem models (Ecopath) is analyzed to study whether the trophic role and feeding habits vary among Mediterranean regions and ecosystems. We obtain a global view of the importance of these species in different areas of the Mediterranean Sea and identify major information gaps. Several predators are found to prey on SMPF, with important contributions of the species studied to the total diet of apical predators. The results reveal that SMPF are identified as pivotal species of the food web playing important ecological roles such as structuring or keystone species. Medium pelagic fish, mainly Scomber spp. are the less studied species, in special in the south-eastern Mediterranean waters. By highlighting the important gaps in the ecological information of these species this study provides a guide for scientist and managers on research priorities in the Mediterranean SeaPeer Reviewe