The Gulf of Manfredonia: a new neritic foraging area for loggerhead sea turtles in the Adriatic Sea

Abstract

The Adriatic Sea is an important foraging area for the loggerhead sea turtle, Caretta caretta, but neritic habitats for this species along the Italian coast were identi- fied in the northern shallow area only. The Gulf of Manfredonia is a relatively wide shallow area in the south-west Adriatic and its features and preliminary information make it a potential foraging ground for turtles. In order to assess sea turtle occur - rence in the area, we monitored seven bottom trawlers based in the port of Manfredo- nia during the period Oct 2010 - Jul 2011 through a voluntary logbook programme, resulting in a total of 62 turtle captures during 617 fishing days. Since a turtle capture represents a rare event during such sampling, data were analysed by a zero-inflated Poisson (ZIP) model. Results indicate that: (i) the Gulf is a neritic foraging ground for loggerhead turtles which occur there with a relatively high density comparable to oth- er Mediterranean foraging grounds, (ii) it is frequented by a wide range of size classes, including small juveniles as well as adults, (iii) the highest occurrence is during the period Jun-Dec, (iv) over 1700 turtle captures occur in the Gulf annually. Preliminary findings about recaptured individuals suggest that part of the turtles are resident in the area. The peculiar features of the Gulf of Manfredonia and the collaboration of the fishing fleet, make it a valuable index site for studying current trends of sea turtle populations at sea as well as other aspects of sea turtle biology and conservation.