meet our sea turtles

Four species of marine turtles come ashore to lay their eggs on Bioko Island's southern beaches from November to February:


Olive Ridley



Binomial: Dermochelys coriacea

Common: Leatherback



Largest sea turtle, with shell length of 52-70 inches and a mass of 550-2000 lbs. Carapace is black with white splotches, plastron is white with black splotches. Carapace is a layer of rubbery skin instead of a hard shell, and is raised into seven longitudinal ridges. Ranges over all oceans except Arctic and Antarctic; Africa’s Gulf of Guinea has one of the largest nesting populations of leatherbacks.

Binomial: Lepidochelys olivacea

Common: Olive Ridley



Average shell length of 22-30 inches and mass of 80-95 lbs. Carapace is olive green in color and plastron is light greenish-yellow. Has a large head and powerful jaws. Ranges tropical Pacific, Indian, and Atlantic Oceans, swimming on drift lines where seaweed and debris gather and there is an abundance of food.


Binomial: Eretmochelys imbricata

Common: Hawksbill



Average shell length of 30-35 inches and mass of 95-165 lbs. Dark amber carapace with radiating streaks of brown or black and whitish-yellow plastron. Narrow head with a strongly hooked beak. Carapace has thick overlapping scutes and is serrated along the posterior edge. Range includes coral reefs throughout tropical oceans.

Binomial: Chelonia mydas

Common: Green



Average shell length of 32-48 inches and mass of 144-450 lbs. Carapace is smooth and light or dark brown, sometimes shaded with olive, with brown blotches or streaks. Plastron is yellowish-white. Name comes from greenish color of their fat which results from their herbivorous diet of sea grasses. Have small, rounded heads. Ranges tropical and subtropical Atlantic, Pacific, and Indian Oceans.

Our work

Marine turtles nest on the 19 km of black sand beaches along the southern shores of Bioko Island’s Gran Caldera and Southern Highlands Scientific Reserve. The nesting season, which peaks in January, corresponds to the dry season on the Island, beginning in September and extending through April.


The first systematic record of Bioko Island turtle nesting took place from 1996 to 1998. Trained local people from the village of Ureca were responsible for daily counts from all the southern beaches. We currently focus on the nesting ecology of the marine turtles and also seek to improve and advance the data collection on the Island. Our attention is focused on Leatherback and Green Turtles, the most frequently nesting species. Since 2007, Leatherbacks have been tagged with unique identification markers during night patrols. In 2013, the tagging program was extended to Green Turtles nesting on the Western beaches, as well.

All photos are credited to National Geographic Photographers Tim Laman, Ian Nichols, Joel Sartore, and Christian Ziegler, as well as numerous members of BBPP (staff, students, and volunteers).