Olive Ridley Turtles of Masirah Island

By Nancy Papathanasopoulou

Masirah Island, Oman, hosts four species of nesting turtles, Logger-heads, Greens, Hawksbills and Olive Ridleys. The Olive Ridley (Lepidochelys olivacea) nesting population is the only important one in the Arabian Peninsula. Mainly due to the difficult access to their nesting beaches, these turtles have hardly been studied at all, and no migration information is available to date. It is hoped that this project will shed light on their feeding, nesting and migrating behaviour.

The Olive Ridley is the smallest turtle, weighing up to 45kg and reach-ing up to 80cm of curved carapace length. They have a sister species, the Kemp’s Ridley, which is the most endangered turtle species on the planet. In Arabic, Olive Ridleys are called “Tekshar”or “Zaytooni”. They are best known for their huge synchronized nestings, called “arribadas”, on some beaches of the world, such as Orissa, India and Ostional, Costa Rica, but in Masirah this is not happening. Unlike those in any other part of the world, Olive Ridleys in Masirah nest on the same beaches as Hawksbills. Like other turtle species, females lay about 100-120 eggs every time they nest. However, like everywhere else, these animals tend to cover their nests in a characteristic “thumping” way, different from all other turtle species.

The main diet of the Olive Ridley consists of crabs and shrimps, but also jellyfish and seasquirts. Their jaws are powerful despite their small size. Threatened like all other turtle species, Olive Ridleys are illegally hunted for their skin, used to make leather (illegally, too) in Mexico. But the biggest threat to these turtles is being caught as by-catch in fishing nets.  A recent study has revealed that turtles of this species dive down to 200 metres. Deepest of all hard-shelled turtles? Possibly. This is still being studied, and it is hoped this satellite telemetry project will demonstrate it.  The Ministry of Environment and Climate Affairs of Oman has recently intensified its efforts to gain more knowledge of sea turtles, focusing on satellite telemetry. Within the context of these efforts and as a continuation of the three-year turtle conservation project, which included the pioneering and successful Loggerhead turtle telemetry mis-sion on Masirah Island in May 2006 (more about that in a future issue of Gazelle),TOTAL S.A. Muscat and TOTAL Corporate Foundation for Biodiversity and the Sea are now sponsoring this Olive Ridley telemetry project. Later, in the summer of 2008, a Green turtle telemetry pro-ject will take place at Masirah pro-viding evidence of migration routes and raising awareness of this threatened and depleted population.

The turtles were sought on what seemed to be the “busiest” beach for Hawksbill and Olive Ridley turtles in Masirah Island this time of the year. A rough beach line of 4 kilometres (south-east beach of Ras Shiban) was scouted by the team every night just before and after high tide. A quota of one to two Olive Ridley and Hawksbill turtles were spotted every night, as well as tracks of previous nesting turtles. Seven turtles received regular location transmitters (Kiwisat 101) and two received location and depth-measuring transmitters.

To find out more about these turtles migrations and follow them on the web, click on the following link:
http://www.seaturtle.org/tracking/index.shtml?project_id=278