Sea turtles

The islands of São Tomé and Príncipe are home to five of the seven existing species of sea turtles and offer optimal conditions for these endangered species, both on the beaches and in the feeding grounds at sea. These populations may have been exploited as far back as the 16th century and are still being exploited. In the last decade, knowledge about these populations has improved a lot, highlighting their regional and global importance. Several conservation initiatives have also prioritized their protection.

History

Sea turtles have been roaming the oceans for millions of years and, with an incredible capacity for resistance, they have survived until today. This is probably why they are so much appreciated and aroused so much interest by the public and scientists alike. Turtles belong to the oldest lineage of living reptiles, having first appeared over 200 million years ago, at the end of the Triassic. But it was probably around 110 million years ago, in the Jurassic, during the reign of dinosaurs, that turtles entered the sea and shared the ocean with various other air-breathing reptiles, such as ichthyosaurs and plesiosaurs. Although the end of the Cretaceous saw the mass extinction of the large reptiles that dominated the Earth, sea turtle lineages have persisted to the present day (Lutz and Musick 1997; Motani 2009).

These large marine reptiles are well adapted to life in the ocean, making vast migrations between feeding and nesting areas that can be thousands of kilometers apart, and inhabiting a variety of neritic and pelagic habitats in tropical and subtropical waters worldwide ( Carr 1982). The oceanic islands of the Gulf of Guinea, particularly São Tomé and Príncipe, are home to important breeding and feeding areas for sea turtles. Nesting areas for sea turtles on Annobón, the smallest island in the Gulf of Guinea, are limited, with only a few suitable beaches available, although important feeding areas may exist (Castroviejo et al. 1994; Frettie 2001).

Turtles in Sao Tome and Principe

The archipelago of São Tomé and Príncipe (Eastern Atlantic) is home to five species of sea turtles, which, in order of abundance, are:

  1. Green tortoise Chelonia mydas (Linnaeus, 1758)
  2. Olive tortoise Lepidochelys olivacea (Eschscholtz, 1829),
  3. Hawksbill Turtle Eretmochelys imbricata (Linnaeus, 1766),
  4. Leatherback turtle Dermochelys coriacea (Vandelli, 1761),
  5. Loggerhead turtle Caretta caretta (Linnaeus, 1758).

It is worth noting the fact that it is on the islands that one of the populations of the Hawksbill turtles (E. imbricata) endangered species in the world, the last population of this species in the eastern Atlantic, which is believed to have been severely reduced as a result of intensive exploitation for the scale trade.

Turtle Conservation in STP

Habitat and Nesting
 
The exceptional environment of the islands offers optimal conditions for colonization by sea turtles, both on nesting beaches and at sea feeding sites.
The islands are characterized by the presence of warm, clear ocean waters, surrounded by shallow rocky reefs, sparsely colonized by hard and soft corals, vast rhodolith beds and a great diversity of macroalgae and seagrass meadows (common in São Tomé). Coastlines change from a long, shallow shelf with low wave exposure on the north coast to shorter, deeper shores more exposed to waves on the south coast of both islands. Fresh water enters the sea from small streams and rivers, forming small estuarine habitats in some areas, with mangroves flanking some of the river mouths. The archipelago has a variety of beaches ranging from golden yellow sand to dark gray or rocky sand, with lengths ranging between 0.17 and 2.11 km.
Nesting of sea turtles occurs on almost all sandy beaches on both islands that offer suitable conditions for nesting, although the distribution and density vary according to the species. The nesting season on both islands coincides with the rainy season, which runs from October to May, providing suitable conditions for nesting and hatching. (Nesting areas -São Tomé; Nesting areas- Príncipe) .

Species Registered in STP

São Tomé, 26 de Julho de 2023