An exciting component of the Sulu Sulawesi Seascape marine turtle research programme recently took place in the astounding Tubbataha Reefs Natural Park and World Heritage Site. The trip was organized by the Tubbataha Management Office (TMO) and once again brought in the expertise of Dr. Nick Pilcher, from the Marine Research Foundation (MRF), based in Sabah, Malaysia.
This was the third of such collaborative efforts by TMO and MRF, having conducted the first back in 2010, and the second in 2014. These last two research expeditions were funded by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH as part of its tri-national Sulu Sulawesi Seascape programme.
The research expedition featured veterinary specialists Dr. Rizza Araceli Salinas from the Biodiversity Management Bureau (BMB) of the Department of Environment and Natural Resources (DENR) and Dr. Teri Aquino from the Tubbataha Management Office and Marine Wildlife Watch of the Philippines, who were there to brush up on their skills working with sea turtles.
The trip demonstrated the use of the latest in scientific techniques, with Dr. Pilcher and the vets using laparoscopy, a form of keyhole surgery, to determine the sex and reproductive status of sea turtles - which cannot be determined through simple external observations.
Sea turtles are cold-blooded reptile whose sex is determined by temperature, and not through the X and Y chromosomes. In sea turtles it is the temperature of the sand that determines if they will become male or female. And with climate change and a warming planet, scientists are concerned there might be impacts on sea turtle population, not only in the local scene but also in overall trends globally.
The team of rangers and WWF’s M/Y Navorca boat crew managed to wrangle 198 turtles and bring them back for inspection, providing robust sample size from which the team could base its scientific findings. Dr. Nick estimated the team caught over 5,900 kg of turtles in five days.
The turtles were brought back to the base ship, where they were measured carefully, tagged, and then inspected using a laparoscope. This is a small scope that is used to look inside the turtles to determine the sex and the age-class. Of those caught, nearly 80% of turtles were juveniles, with just 17% sub adults and 5% adults. This suggests that Tubbataha is mostly a development ground for small turtles.
The examination also revealed that 69% were female which is quite common in turtles of this size in other parts of the world (roughly two-thirds). It is observed, however, that as turtles mature towards adulthood, the sex ratio balances but to nearly 50:50.
In Tubbataha most of the turtles were between 60 and 70 cm in length, and not yet considered adults. The team of scientists involved in the expedition has been trying to figure out if they will grow and stay on the Tubbataha Reefs, or move on to some distant nesting grounds, which can only be determined by genetic studies.
The team also recorded an 8% influx of new recruits – turtles that had never been to reefs before – showing that there is a healthy life cycle going on.
The research concluded that the turtles were all in excellent condition, and contributing to the life cycle of sea turtles in general in the Sulu Sulawesi Seascape. #