Brunei Releases Olive Ridley Turtle Fitted with Transmitter
Researchers in Brunei are studying the migration route and nesting habitat of Olive Ridley Turtles by monitoring the satellite transmitter of a recently-released female turtle.
Earlier this month, a female Olive Ridley Turtle (Lepidochelys olivacea), fitted with a satellite transmitter, was released from Meragang Beach as part of a Southeast Asia Fisheries Development Centre (SEAFDEC) project.
The ability to track this turtle will help locate breeding and nesting grounds, so that conservationists can manage and protect these sensitive sites. By checking daily transmissions, researchers can determine the turtle’s route.
Attaching the transmitter to the turtle’s shell was done with a special glue and then covered with fiberglass, a common method used by researchers to track long-range migration habits of sea turtles.
The extraordinary nesting behavior of the Olive Ridley Turtle
Female Olive Ridley Turtles are responsible for one of the most unusual occurrences found in nature. In a phenomenon known as arribada (”arrival by sea”), it begins when groups of females congregate in the water near nesting sites.
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Then, in a strange, synchronized movement, thousands of these sea turtles head for the beaches to excavate nests and lay their eggs all at once. In fact, there can be so many females nesting that some are laying eggs right on top of other nests.
While some other species of marine turtles have been observed nesting in groups, it is unlike the mass synchronization of the Olive Ridleys.
There are many theories on what triggers an arribada, including offshore winds, lunar cycles, and the release of pheromones by females. Despite these theories, scientists have yet to determine the actual cues for ridley arribadas. Not all females nest during an arribada, instead some are solitary nesters. Some olive ridleys employ a mixed nesting strategy. For example, a single female might nest during an arribada, as well as nest alone during the same nesting season. Arribada nesting is a behavior found only in the genus Lepidochelys.
Population is declining
Although the Olive Ridley has the highest population of any marine turtle, the species is currently classified as vulnerable by IUCN. An unfortunate number of factors are causing the Olive Ridley Turtle population to decrease, including perhaps global warming.
For the Olive Ridley Turtle, as with most turtle species, the sex ratio of the hatchlings is influenced by incubation temperature. Cooler incubation temperatures produce all male hatchlings, while warm incubation temperatures result in all female hatchlings.
Thus, an overabundance of female turtles could result from global warming’s increased temperatures at nesting sites. This may affect many species of turtles - and other reptiles as well.
Other threats include:
- Unsustainable egg harvesting
- Widespread killing of females as they nest on beaches
- Bycatch in fisheries (trawl fisheries, longline fisheries, purse seines, gill net, and hook and line fisheries, etc.)
- Habitat destruction due to coastal development for fishing harbors and tourist facilities
By applying the research gathered from the Brunei turtle study, additional protection programs for the Olive Ridley can help reverse the population trend of this species before they move further down the IUCN red list.
Image source: http://www.flickr.com/photos/man_of_mud/ / CC BY-NC-SA 2.0
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