Scientific Name: Lepidochelys olivacea
The olive ridley, Lepidochelys olivacea is classified under the family Cheloniidae. This species is relatively small, when compared to other turtles and it has an adult carapace with an average length of 60 to 70 cm.
Being included in the family Cheloniidae, the olive ridley is thus also related to the Kemp’s ridley (and it is in fact in the same genus of this species), which was described in Newsletter issue 11. The olive ridley is distinguishable from the Kemp’s ridley since the latter generally has 5 pairs of costal plates (lateral scutes) whilst in the former; they range from 5 to 9 pairs of costal plates. The pattern of plates/scutes on the head (two pairs of prefrontals), the number of costal scutes (asymmetrical lateral plate ranging from five to 9 plates on each side) and the presence of inframarginal pores are diagnostic features for the olive ridley.
The olive ridley has a circumtropical distribution and occurs regularly in the Pacific and Indian oceans. It is also globally distributed in the tropical regions of the South Atlantic, Pacific, and Indian Oceans. In the South Atlantic Ocean, it is found along the Atlantic coasts of West Africa and South America. In the Eastern Pacific, they occur from Southern California to Northern Chile. Arribadas (see further below) however, occur on only a few beaches worldwide, in the eastern Pacific and northern Indian oceans, in the countries of: Mexico; Nicaragua; Costa Rica; Panama and India.
The olive ridley mainly feeds on fish and invertebrates, including molluscs, crustaceans and jellyfish. It exhibits mass nesting behaviour where literally thousands of females come ashore to lay eggs at the same. This unique nesting event (which does not occur in the Mediterranean for any kind of species, although the olive ridley is not considered a Mediterranean species) is called an arribada, which is a Spanish term for the word arrival. This type of mass nesting has the advantage of ‘saturating’ the natural predators of the turtles. In fact, when the hatchling come out, mostly at the same time, noting that nesting occurred at the same time, being so many, predators quickly reach the satiety, giving the chance to the ‘survivors’ to get in the water. Although arribadas have such advantages, they also have the disadvantage that during nesting the females may not only compete for space, but may also disturb each other and each other’s nest.
This species is categorised as vulnerable in the IUCN Red listing guidelines for Red List Assessments, the focus of this evaluation has been the number of mature individuals (IUCN 2001). For olive Ridley, as with other sea turtle species, as it is not possible to survey mature individuals they used an index of abundance in the form of the number of annual nesting females”. This species is also listed in Appendix I of the Convention on International Trade in Endangered Species of Flora and Fauna (CITES- lists species that are most endangered; appendices I, II, III are lists of species afforded different level or types of protection from over-exploitation).
The olive ridley is also protected by various other international treaties and agreements as well as national laws, amongst which:
* CMS: listed in Appendices I and II of the Convention on Migratory Species and are protected under the following auspices:
– IOSEA: Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats of the Indian Ocean and South-East Asia;
– Memorandum of Understanding Concerning Conservation Measures for Marine Turtles of the Atlantic Coast of Africa;
– SPAW: protected under Annex II of the Specially Protected Areas and Wildlife Protocol of the Cartagena Convention;
– IAC: The U.S. is a party of the Inter-American Convention for the Protection and Conservation of Sea Turtles, which is the only international treaty dedicated exclusively to marine turtles.
Though not a Mediterranean Species, on 8 May 2014, a carcass of a stranded sea turtle found in the town of Oropesa del Mar on the Mediterranean coast (East of Spain), was positively identified to be that of an olive ridley. The olive ridley was identified based on prefrontal (2 pairs), costal (7 pairs) and vertebral scutes (7 pairs) and also on the presence of pores in the inframarginal plates.