Diet of bluefin tuna (Thunnus thynnus) and swordfish (Xhipias gladius) in the Adriatic Sea

Ciavaglia, Elisa (2011) Diet of bluefin tuna (Thunnus thynnus) and swordfish (Xhipias gladius) in the Adriatic Sea, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Biodiversità ed evoluzione, 21 Ciclo.
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The present issue analyses bluefin tuna (Thynnus thunnus) and swordfish (Xiphias glaudis) diet, caught by professional long-line fishing in the middle Adriatic Sea (Pomo pit). These species represent apex predators in pelagic environment that may play key roles in determining food web structure and ecosystem dynamics. The studies about their feedings habits, based upon stomach contents analysis, are important for the comprehension of biological and ecological interaction. Over the years, many studies have been performed on the diet of tuna and swordfish in the Mediterranean Sea. This research is based on a fairly wide number of analyzed stomach contents, in comparison with the previous ones. In this work, the analysis of 340 stomach contents of bluefin tuna caught by long-line in the central Adriatic sea confirms in general the opportunistic behaviour of this species. Finding support the hypothesis that Adriatic tuna and swordfish chase their food over a wide bathymetric zone and probably near the surface at night. No indication of food preference respect to size of predator or sample season are found. It seems that the two species are able to cohabit because their trophic niche are not overlapped, changing during the time and the vertical and horizontal space.

Tipologia del documento
Tesi di dottorato
Ciavaglia, Elisa
Dottorato di ricerca
Scuola di dottorato
Scienze biologiche, biomediche e biotecnologiche
Settore disciplinare
Settore concorsuale
Parole chiave
bluefin tuna swordfish adriatic sea diet
Data di discussione
4 Maggio 2011

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