Olive ridley turtle  (Lepidochelys olivacea)

Nesting in such large congregations, the olive ridley turtle is particularly vulnerable to human activities such as development and exploitation (8). This turtle has been extensively over-harvested for its eggs and meat; on the Mexican Pacific coast in the 1960s over one million individuals were killed each year (8). In Central and South America there is still a massive market for the now illegal turtle eggs, which are traditionally believed to have aphrodisiac properties (10). Artificial illumination from development poses an additional threat, and disorientates both adults and hatchlings on the nesting beaches (8). One of the most important threats to the olive ridley is incidental catch (bycatch) by the fishing industry; turtles caught in trawl nets drown and are then discarded (7). Between 1993 and 1999, more than 50,000 dead turtles were found along the Orissa coast in India, primarily as a direct result of illegal fishing in the area (11).

Numbers of marine turtles are notoriously difficult to investigate given their oceanic habitat and worldwide distribution. International trade in olive ridley turtles and products is banned under their listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) but a significant illegal trade (particularly in eggs) still occurs (8). TRAFFIC (the wildlife trade monitoring arm of WWF and the IUCN) is involved in monitoring black market trade and bringing it to the attention of relevant authorities (2). The fitting of Turtle Excluding Devices (TEDs) to shrimp-trawl nets offers an encouraging step in their conservation; a 'trap-door' in the net allows the large turtles to escape (7). Their use is still not widespread however, and even in countries where the use of TED's is mandatory, this is not enforced (9). A number of major nesting beaches are protected and conservation projects work to artificially rear turtle eggs and then release them. Recently the number of olive ridleys nesting in Mexico has increased (12), and arribadas have returned to the Gahirmatha rookery in Orissa, India (9); perhaps offering a glimmer of hope that conservation efforts are working.