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The loggerhead turtle, Caretta caretta, is considered the most common sea turtle species in the Mediterranean and is therefore included in most international wildlife conservation treaties (Eckert et al. 2000). Groombridge (1990) recommended that this species should be possibly considered as critically endangered for the Mediterranean region.
The main nesting concentrations of the loggerhead turtle in the Mediterranean are confined almost exclusively to the eastern basin (mainly Greece, Cyprus, Libya and Turkey) (Margaritoulis et al. 2003). Demographic studies indicate that the loss of late juveniles (straight carapace length = 30 to 80 cm) and adults has a more dramatic impact on populations than the loss of younger individuals such as eggs, hatchlings and younger juveniles (Crouse et al. 1987). Therefore, although rookery protection has been a priority for marine turtle conservation, this measure will be unsuccessful without the effective protection of large juveniles and adults. In fact, the impact of fishery related mortalities is one of the most important anthropogenic factors for loggerhead turtles in the Mediterranean. An assessment of fisheries interactions and associated mortalities is one of the priorities adopted by the Action Plan for the Conservation of Mediterranean Marine Turtles (RAC/SPA 2001).
More than 150,000 captures per year may take place in the Mediterranean by trawlers, longliners and set netters, with possibly over 50,000 deaths per year. Bycatch is drastically high in the western part of the Mediterranean especially around the Balearic Islands (Aguilar et al. 1995; Caminas et al. 2001) where there is an occurrence of a high concentration of sea turtles due to the entrance of animals from the Atlantic Ocean via Gibraltar (Argano et al. 1992; Caminas & De la Serna 1995).
Results obtained from genetic markers (Casale et al. 2008) and tagging programs (Bradai et al. 2009; Bentivegna 2002) lead to the conclusion that the region of the Gulf of Gabes (Figure 1) is an important wintering and feeding area for the loggerhead turtle in the Mediterranean Sea. In this region, a fleet of dozens of fishing vessels, using many kinds of fishing gears (including longline, trawl, gillnet and trammelnet), operating during different seasons and targeting a wide variety of commercially important species, interacts with this endangered species. In order to assess the importance of potential threats for different...