6th September, Oxford - Our main research objective was to determine the population status and conservation needs of the green sea turtle (Chelonia mydas) in Peninsular Malaysia. With the assistance of the volunteers we studied the morphology and egg production of 36 adults, and the reproductive and population ecology of 153 nests containing approximately 15,000 eggs. During the study period, the four groups of volunteers were directly involved in the release of over 5,000 green turtle hatchlings from mainland and island beaches.
From these nests, an additional 3,010 hatchlings were measured and weighed and tested for morphological abnormalities, running performance, ability to flip themselves back to the upright position and ability to orient themselves to the ocean. The data analysis is also being completed and results are being formulated to provide recommendations for future research into conservation management of this species.
The project in 2004 confirmed and extended information about hatchling quality, mainly through observations of hatchlings ability to run down the beach, flip themselves back to the upright position and orient themselves towards the ocean, and in morphological measurements of size and scale abnormalities. The long running comparison of hatchling quality between hatchery and in situ hatchlings entered its fifth year, revealing seasonal and spatial variations over this period. The longevity of this study is proving to provide valuable information that only studies of this time span will allow.
The delayed release experiment we ran this year revealed that retaining hatchlings after they emerge (a practice inherent to hatchery operation) compromises running speed and the energy available for offshore dispersal. Similarly our delayed excavation experiment found that hatchlings excavated immediately after the primary emergence had similar running speed and mass:length ratios (a measure of energy available for dispersal) to emerged hatchlings and significantly higher than hatchlings that were excavated 5 days after the primary emergence.
From these results, we have recommended to the Fisheries Department of Malaysia that hatcheries be checked at least every thirty minutes to release all emerged hatchlings and that nest be excavated immediately after the primary emergence to maximize the vigor and energy available for off shore dispersal.
Volunteers greatly aided in efforts to determine the status of the nesting population of green turtle in Peninsular Malaysia. In conjunction with village staff and rangers, more comprehensive nesting beach surveys and tagging studies were conducted, allowing basic population data to be gathered. The data are now being compared to past censuses of turtle nesting.
In addition to the ongoing hatchery monitoring and nesting census data collection we have also developed two new PhD proposals, which began this year. Jason van de Merwe is investigating the effects of chemical pollutants on sea turtles and this year collected blood and eggs from nesting females and hatchlings. He will shortly analyse these samples and find the results over the next few months. Maria Ikonomopolou is focusing on how steroid hormones in the females play important signalling roles in nesting animals. She is currently analysing blood samples collected in 2004 for hormone binding activity and in future will examine the effects of persistent pollutants on these internal reproductive processes.
Click here to read the full 'Green Turtles of Malaysia' field report.
Photo credits: © Norbert Wu, © Flavia Ribeiro Pessanha (winner of the Earthwatch 2004 Photo Competion), © Jen Alger.