Marine turtles are integral components of marine ecosystems at the Tubbataha Marine Park World Heritage Site, and priority conservation species Nationally and within the Sulu-Sulawesi Seascape programme, the IOSEA MoU, the CTI Regional Action Plan, and the ASEAN Sea Turtle MoU. The reefs at Tubbataha, Cagayancillo, Palawan, Philippines, are a developmental and nesting habitat for Endangered green turtles (Chelonia mydas), and a foraging habitat for Critically Endangered hawksbill turtles (Eretmochelys imbricata).
Understanding population dynamics in breeding and foraging habitats is a vital part of assessing the long-term viability of any species, particularly those that are highly migratory, to detect early signs of population trends that would otherwise take decades to be seen at the nesting beach. An understanding of the life-stage dynamics of stocks at Tubbataha Reefs National Park will assist managers in the development and implementation of sound, effective conservation strategies which build on the biological characteristics of the turtles.
The objectives of MRF’s work are to conduct population abundance estimates of marine turtles at Tubbataha, to gather data on population structure and dynamics of marine turtles, and to analyse the first series of data from a long-term monitoring programme. In addition, a training component is included to build capacity amongst staff from Philippines agencies.
Turtles are captured using rodeo or SCUBA and are assessed for gender and life stage using laparoscopy. They are also measured and tagged because capture-mark-recapture studies allow assessments of growth rates, residence periods, migrations and age-specific mortality. Training on collection of accurate data, maintenance of records, field procedures, and turtle measurements and genetic sampling ss provided to staff from the Tubbataha Marine Park, the Turtle Islands Wildlife Sanctuary, the Palawan Council for Sustainable Development, and the veterinary office of the Biodiversity Management Bureau, department of Environment and Natural Resources. The latter also were trained in surgical procedures and interpretation of gonad status as part of the laparoscopy process.
Tubbataha is an important juvenile sea turtle developmental habitat, isolated in the middle of the Sulu Sea, and mostly devoid of anthropogenic pressures. The reefs are also home to a smaller number of sub adults. It is unknown if the adult turtles are of the same genetic stock as the juveniles, and grow up and mature at Tubbataha and remain to nest, or if they are a genetically distinct aggregation which migrate to Tubbataha just to nest, and return to their foraging grounds thereafter. Genetic studies will reveal any linkages between nesting and foraging grounds, and genetic origin.
This work has been funded by the Tubbataha Management Office (TMO), and by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) Philippines on behalf of the German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB), which provided grants to TMO and to MRF.