Understanding the Movement of Green Turtles in Terengganu, Malaysia through a Shared Photographic Identification Database

Photographic identification (photo-ID) of sea turtles through facial scale patterns has been increasingly used for population studies. This study aims to determine the movement patterns of green turtles between Lang Tengah... [ view full abstract ]

Photographic identification (photo-ID) of sea turtles through facial scale patterns has been increasingly used for population studies. This study aims to determine the movement patterns of green turtles between Lang Tengah Island and Perhentian Island in Terengganu, Malaysia through a shared photo-ID database. The database consisting of photographs of the left and right facial scale patterns of green turtles from Perhentian Turtle Project (PTP; 181 nesting and 66 in-water individuals) and Lang Tengah Turtle Watch (LTTW; 12 nesting individuals) were consolidated in 2017. All photographs were run through an automated pattern matching software, Interactive Individual Identification System Pattern (I³S), which produced a list of matches based on a match score starting from 0 (perfect match) to over 100, or "No Match". The list was visually checked for any correct matches. A nesting green turtle from LTTW database was successfully matched to an in-water green turtle from PTP database, suggesting movements between nesting and foraging sites that is 20 km apart. The turtle has been sighted 44 times at the same foraging site at Perhentian Islands from 2013-2016, and was found nesting once at Lang Tengah Island on 2 June 2017. This study shows the efficacy of I³S in matching individuals within a shared database, provided that the photographs are of high resolution and the facial scales are visible. The match found indicates the potential of a shared photo-ID database in having a better understanding of the movements of sea turtles between nesting and foraging grounds in a wider geographical area.