Multidirectional migrations from a major nesting area in Turkey support the widespread distribution of foraging sites for loggerhead turtles in the Mediterranean

Abstract

Satellite tracking studies have identified some of the migratory corridors and foraging sites of Mediterranean loggerhead sea turtle (Caretta caretta) rookeries over the past few decades. However, due to a lack of information for breeding rookeries in Libya and Turkey, our understanding of the distribution and connectivity of adult loggerheads is limited. We satellite-tracked 17 female loggerhead turtles breeding in one of the main nesting areas in Turkey to identify (1) migratory pathways, and (2) their foraging areas. Females were tracked for 96-657 d (mean: 271 d), and followed 3 general migratory directions (southeast, southwest and northwest/west). While migrating, individuals alternated oceanic and neritic movements, generally travelling significantly slower when in neritic waters (average speed reduction: 20%). Five turtles stopped between 1 to 3 times in stopover sites for <6 d before resuming their migration. While 1 turtle resided in oceanic foraging areas, the remaining 16 loggerheads settled in 12 distinct neritic foraging grounds; 2 turtles shared one site and 4 turtles shared another site. The identified foraging grounds were widely distributed across the Eastern and Central basin, in locations known to be frequented by loggerhead turtles from other rookeries. The present findings reveal links between foraging areas and one of the main breeding sites in Turkey, providing useful information for species conservation.

Habitat use and distribution of the loggerhead sea turtle (Caretta caretta) in the Mediterranean Sea: Implications for marine planning strategies

“…Previous studies suggested that adult loggerheads in the Mediterranean Sea inhabit foraging grounds usually hosted at the neritic zone (Wallace et al 2011, Zbinden et al 2008, 2011, Casale et al 2013, Luschi et al 2013, Mingozzi et al 2016, Snape et al 2016, Almpanidou et al 2022, and exhibit smaller home ranges than those turtle life stages that inhabit oceanic habitats (Schofield et al 2010, Snape et al 2016. However, recent studies suggested that adult turtles in the Mediterranean may alternate between neritic and oceanic habitats due to the short distance between the two types of habitat in the Mediterranean basin (Ten et al 2019, Cerritelli et al 2022, Baldi et al 2023.…”

“…Only one female (turtle ID Victoria), which was satellite-tracked more than 2 years (and counting), frequented neritic foraging grounds for a 3-month period at the Tunisian Plateau and Libyan coastal waters before returning to the western basin, suggesting that this foraging area is used by females nesting on the western basin. The Tunisian Plateau and the coast of Libya are known foraging grounds for adult loggerhead turtles from other Mediterranean regions (see Mingozzi et al 2016, Levy et al 2017, Almpanidou et al 2022, Cerritelli et al 2022). This result supports previous studies in which adult individuals from a given breeding rookery might use different foraging grounds, often separated by hundreds of kilometres (Bentivegna 2002, Zbinden et al 2008, Schofield et al 2010a, Schofield et al 2013.…”