Studying the feeding ecology of an organism is essential to understanding its ecological role in the ecosystem. This study presents new geographically information about the feeding ecology of little tunny, Euthynnus alletteratus, in the western Mediterranean Sea. Here, by combining analyses of stomach contents and stable isotope values, we examined the diet of little tunny in four areas of the Mediterranean Sea (Tarragona, Valencia, Cartagena and Ceuta). Results indicated that the main preyed families of little tunny in Tarragona were Engraulidae and Clupeidae. In Valencia, where they have the smallest body lengths, the diet was composed mainly of small mesopelagic crustaceans. The stomachs from Cartagena and Ceuta stomachs were completely empty. Nevertheless, with stable isotope analysis we observed significant differences between the isotopic niche of the four sampling areas. In conclusion, the results highlight the dependence of adult little tunny from small pelagic fish, as its main trophic resource consumed. Small individuals rely more on crustaceans

Trabajo final presentado por Eric Moron Rubio para el Máster en Oceanografía y Gestión del Medio Marino de la Universitat de Barcelona (UB), realizado bajo la dirección del Dr. Joan Giménez, el Dr. Joan Navarro y la Dra. Marta Coll del Institut de Ciències del Mar (ICM-CSIC) y de la Dra. Ana Sotomayor García.-- 27 pages, 5 figures, 6 tables

This work is a contribution to the Spanish Government PELWEB project (ES-PN-2017-CTM 2017-88939-R) and to the RyC (RYC-2015-17809) contract of J. Navarro