Turtle Photo-ID – Tracking Turtles Through Images

How Many Marine Turtles Are There? Where Are They?

As of August 2020, ORP has identified 3,184 unique hawksbill turtles and 841 unique green turtles, and logged more than 25,456 sightings of marine turtles in the Maldives. Each month we add another 400+ new sightings to our Turtle Photo-ID database – one of the largest such databases in the world. We identify sea turtles using a technique called Photo-ID, or PID; this is the process of recognizing individual animals of a species from unique markings on their body from photographs. ORP staff and volunteers, researchers, tourists and local residents contribute turtle photos to our Turtle Photo-ID database.

Meet Some Of The Turtles Of The Maldives

The Indian Ocean is home to five out of the world’s seven turtle species. The hawksbill turtle is the most abundant species in the Maldives. Sea turtles like to stay on their “home” reef and rarely moving between reefs. So far, no turtles have been sighted moving between atolls.

Marine Turtles – Elusive Study Objects

Green turtle Clio identified by ORP Turtle Photo-ID Maldives
Clio, green turtle © Jasmin Pape

Marine turtles spend about 90% of their lives at sea. In addition, they are truly global citizens, crossing oceans, feeding and nesting on the shores of many different countries. The migratory nature of marine turtles makes them rather difficult to study. Although there are many things we do not know about turtles, years of research have provided insights into daily activities and behaviours such as feeding, courtship, mating and nesting. Most marine turtle research and conservation efforts happen on nesting beaches because they are more easily accessible than the open ocean. Nesting beaches are extremely important to the survival of marine turtles. However, marine turtles spend most of their life time in the water. What they do in the water, where they go, and the threats they face in the ocean, are still largely unknowns.

Why Identify Individual Turtles?

Snorkler taking photo of hawksbill turtle for ORP Turtle Photo-ID Maldives
Citizen scientist in action, photographing a turtle in Maldives for the ORP Turtle Photo-ID Project © Lisa Bauer

All seven species of marine turtles are threatened by extinction. Extinction means they will be gone forever. To create effective conservation strategies, we need to fill the gaps in our knowledge; we need reliable information to study the population structures, distribution, habitat use and migration pattern of all marine turtle species.

The ability to identify individuals is often a starting point for ecological and conservation studies. Statistical modelling of a series of photos can reveal patterns of residency and movement between reefs, and therefore help determine the population and population structure of a reef at a given time, calculate inter-nesting periods, etc.

Turtle photo-id Maldives
Turtle Photo-ID in action © Lauren Arthur

A global-scale database of marine turtle information will help researchers identify the most important marine turtle nesting and foraging areas in need of protection, and the highest priority conservation actions. In addition, it will enable researchers to measure the effectiveness of conservation efforts and inform strategic conservation decisions world wide.

The ORP Turtle Photo-ID database can be combined with the Maldivian government’s TurtleWatch database to interpret sea turtle population and movements in the Maldives, as well as to develop and evaluate turtle conservation measures. TurtleWatch aims to collect standardized data on foraging and nesting sea turtles throughout the Maldives.

Left profile of Keno hawksbill turtle ORP Turtle Photo-ID Maldives
Keno, hawksbill turtle, left profile

ORP is also working with other groups around the world to develop “The Internet of Turtles”. IoT is a global data-sharing platform for Photo-ID research. Efforts by the SWOT Team over the past several years is finally making a global-scale database a reality. The Olive Ridley Project is contributing data to the SWOT Team through the Turtle Photo-ID Program.

Photo-ID: “Capture-Mark-Recapture”

Diver taking photo of turtle under water for Turtle Photo-ID Maldives
Diver taking photo of turtle under water for Turtle Photo-ID Maldives

Photo-ID is a scientifically proven method of “tagging” animals. Individual turtles can be ID’d by comparing their facial scales, which are unique like a finger print. This method (developed by Jean et al. (2010) is a cost-effective, non-invasive technique that can easily be used to monitor marine turtles without disturbing them. It is also a great way to involve “citizen scientists”, that is members of the general public with little to no scientific training.

Graphic showing the unique facial scales of two turtlesThus far, marine turtle researchers have used standard ‘capture-mark-recapture’ methods based on flipper tagging or satellite tagging (PTT) to monitor turtles. Tagging is costly and can cause stress to the turtle. Furthermore, tags seldom stay attached for a lifetime and are also difficult to apply, thus limiting the number of deployed tags and the participation of untrained volunteers and citizen scientists.

Technological developments are creating promising new methods to conduct marine turtle research and turtle identification. Photo-ID is rapidly becoming an effective tool for identifying individual turtles and long term monitoring of the marine turtle population.

How to Submit Photos to Turtle Photo-ID

Citizen scientist taking photo of Lucia for ORP Turtle Phot-ID research Maldives
A citizen scientist photographing a turtle in the Maldives © Lisa Bauer

If you would like to contribute to the Turtle Photo-ID project, please email seaturtleid@oliveridleyproject.org for more information. We need one clear image of each side of the turtle’s face. And of course, we also need to know the time and the location of the sighting.