Face ID way to keep track of turtles

The unique features on a turtle’s head.

MANY might not know this, but the faces of turtles are like the thumbprints of humans.

They have diverse patterns and features that are unique and exclusive for each turtle, and that is how scientists keep track of these species individually, apart from using tagging methods to keep track of their movements and population count.

Jeethvendra, science officer at the Tropical Research and Conservation Centre (TRACC) at Semporna’s Pom-Pom Island, said scientists have in recent years started switching from tagging to using face IDs to keep track of the turtle population in the area.

“We find that this is a more non-invasive way to gather data and it is more inclusive because we are able to identify or tag not just the females that come to shore to lay their eggs, but also the males and juveniles,” he said.

He said turtle face identification is actually not a new technology, as it is being practised elsewhere but for Malaysia, this method has gained traction over the past decade or so.

“It has been done elsewhere and on other species such as whale sharks or manta rays, because the patterns on their faces are unique to the individuals, like our thumbprints,” said Jeethvendra.

He said the left and right side of the turtles’ heads have special features that differentiate them from other individuals. For example, in leatherback turtles, there are special markers on the top side of their heads.

To complement photo identification, scientists are also implementing laser photogrammetry, which measures the size of the turtle’s carapace that allows them to work out its age.

“This is basically projecting two parallel laser beams of a known fixed distance over the turtle’s shell and then we can extrapolate the entire shell length using photogrammetry,” Jeethvendra said.

He said a straight carapace length (SCL) of between 60-80cm would be that of a sub-adult, while an SCL of over 80cm could be considered an adult while those smaller than 60cm would make it a juvenile.

“This information is important to gather and classify according to their maturity because it lets us know how turtles are using their habitat, whether as foraging or nesting grounds,” he said.

Jeethvendra said if an area has a large proportion of juvenile green turtles, then scientists can say that the area is an important foraging ground or developmental habitat.

On the other hand, if they find only adults in an area but a lack of juveniles and sub-adults, then they can say that the area is used for breeding or nesting.

Jeethvendra said the importance of knowing the functions of a habitat is so they can understand how to prioritise protection for the species.

“For example, if it is an important nesting area then we should protect the beach from land reclamation activities,” he said.“As for a foraging ground, specific protection would include reducing the impact of boat traffic and to protect seagrass habitats (food source for green turtles),” he added.

Jeethvendra said with cameras and technology getting better by the day, more people are diving and getting into underwater photography.

He said they take advantage of these changes and encourage more divers to be their volunteers and contribute to turtle face IDs.

“In a way, the scientific community is looking for less invasive methods and this is one of them because we do not need to contact the turtles. You just take photos from afar,” he said.

Jeethvendra said with his work in Pom-Pom Island, together with other partners and researchers since 2018, they have managed to identify a total of 600 green turtles and 30 Hawksbill turtles so far.

He said although turtles are mainly migratory, they would call a place home if it provides enough food and shelter and fewer threats from human activities.