Large-scale movements in the oceanic environment identify important foraging areas for loggerheads in central Mediterranean Sea

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Loggerhead sea turtles (Caretta caretta) are known to display a wide range of movement patterns during the different stages of their life cycle, but empirical information to document this extensive behavioural plasticity is still limited. This is especially true for large, adult-sized individuals, that are thought to mainly forage in neritic areas. In the present paper, eight adult-sized loggerhead turtles were tracked using satellite telemetry to identify the location of their foraging grounds in the seas along the western coast of the Italian peninsula. Tracked turtles mostly stayed in the region between the Italian peninsula and the islands of Sicily and Sardinia, that was reached following quick, directed movements by the turtles from a release site to the north. In this area, two turtles took up residence in spatially limited neritic sites along the coast, while the remaining six alternated circumscribed coastal stays with long-distance, circuitous movements in the oceanic environment. An utilization distribution analysis clearly identified an area, mostly comprising oceanic waters, that was continuously used by turtles in different seasons and years. The present results contribute to the still-limited knowledge of the spatial ecology of loggerheads frequenting the Western Mediterranean Sea and highlight the presence of a potentially important oceanic region in the Southern Tyrrhenian Sea where adult-sized turtles forage for extended periods. These findings increase our knowledge of complex life history traits of loggerhead turtles and provide important information to be considered for evidence-based conservation measures.

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The authors are grateful to Mariapia Ciampa, Gianluca Treglia, Fulvio Maffucci and the staff of Punta Campanella Marine Protected Area, TartAmare and A.D. Club Subacqueo Grossetano (Grosseto) for their help in the recovery and releases of tracked turtles. Funds were obtained from SZN, University of Pisa (Progetti di Ricerca di Ateneo, Grant #PRA_2016_1) and Regione Toscana (Bando Go-Green Mare 2014). One satellite tag was purchased from a Grant to G. C. Hays from the Natural Environment Research Council of the U.K. (NERC, Grant NER/A/S/2003/00302).

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Correspondence to Paolo Luschi.

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All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted. Transmitter deployments were authorised by the Italian Ministry of Environment (Prot. nos. 002451/PNM, DPN-2010-0000872, 0042848/PNM 09 and DP-2009-0023740).

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Luschi, P., Mencacci, R., Cerritelli, G. et al. Large-scale movements in the oceanic environment identify important foraging areas for loggerheads in central Mediterranean Sea. Mar Biol 165, 4 (2018).

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