Assessment of Important Marine Turtle Nesting Populations on the Southern Coast of Bioko Island, Equatorial Guinea

Abstract Bioko Island's southern beaches are important nesting sites for marine turtles in the Gulf of Guinea region. In this study, we present data on the 4 species of sea turtles nesting on 5 nesting beaches (19 km) of Bioko Island, from 2000 to 2014. A total of 43,860 leatherback (Dermochelys coriacea), 16,778 green (Chelonia mydas), 1731 olive ridley (Lepidochelys olivacea), and 85 hawksbill turtle (Eretmochelys imbricata) encounters, defined as the number of tracks, were recorded on Bioko's southern beaches. Since 2008, the estimated number of leatherback females ranged from 42 to 444, green turtles from 63 to 649, and olive ridley turtles from 22 to 53 annually. This study presents the first extensive tagging program on Bioko Island, where 790 leatherback turtles were tagged with Passive Integrated Transponder tags from 2008 to 2014. Only 6.1% of the tagged turtles returned to nest again with a remigration interval of 3–4 yrs. In addition, 279 green turtles were flipper-tagged in the 2013–2014 nesti...