Traditionally, researchers studying sea turtles have relied on conventional ‘capture-mark-recapture’ (CMR) techniques, which involve tagging turtles with flipper tags or satellite transmitters (PTT). However, tagging is expensive and can be stressful for the animals.

Additionally, tags rarely remain attached for the turtle’s entire lifespan and are challenging to apply, restricting the number of tags that can be deployed and limiting involvement from untrained volunteers and citizen scientists.

In contrast, photo identification (Photo-ID) offers a low-cost, non-invasive alternative that allows for easy monitoring without disturbing the turtles. This method has been scientifically validated as a reliable way to “tag” animals.

Photo-ID works by analyzing the unique facial scale patterns of individual turtles, a technique proven to be more effective than traditional tagging in a 2008 study by Reisser et al. These facial scales are as distinctive as fingerprints and remain unchanged over time.

Today, Photo-ID is increasingly being used as an efficient tool for identifying individual turtles and tracking populations over the long term. It has been adopted worldwide, from Brazil to Reunion Island and Malaysia. Moreover, it provides an excellent opportunity to engage citizen scientists—members of the public without formal scientific training—in conservation efforts.