Flipper tagging is a low-tech and low-cost method to better understand marine turtle migration patterns, distribution, growth and mortality rates, reproductive output, and population size. It also shows linkages between nesting and foraging areas, when caught during that period. Therefore, flipper tagging is the most common type of tagging in the IOSEA region and can be used in combination with other technologies, such as satellite telemetry (satellite tagging). The tag usually consists of a letter or letters as prefix and a series of numbers on one side, and the return address on the other. The group running the tagging programme will keep a record of when and where this tag was applied, the species of turtle, its size and age class, and any other relevant information.

When a tagged turtle is encountered again, e.g. when it is returning to its nesting beach, or is caught at sea, the location and circumstances of the encounter and the condition, size and behaviour of the turtle provide important information on e.g. reproductive biology, movements, strandings, residency and growth rates. By means of the letter and number code on the tag, the origin of the turtle can be determined, and the new encounter linked to previously collected data.

The story of a Flatback Turtle known as X23103, which was flipper-tagged in 1974 at the nesting beach “Mon Repos” (Queensland, Australia) and has been coming back ever since to lay her eggs (read more about her here) illustrates the wealth of information that can be obtained through long-term tagging programmes. Data collected from flipper tag recoveries and satellite tracks of green turtles in the Western Indian Ocean has revealed complex migration patterns across the region, such as links between Seychelles and the continental coast, as well as connections between Somalia, Kenya, Tanzania and Mozambique (more information here). At the IOSEA Turtle Site Network site Sheedvar Island (Persian Gulf), tag returns recorded since 2005 have helped identify important nesting sites of hawksbill turtles to allow their protection, and data was collected on the clutch size, eggs, hatchlings and turtles (more information here).

Since 2005, the IOSEA Marine Turtle MOU Secretariat has maintained a database of flipper tag series in use in the IOSEA region. It now includes information from 25 countries. Besides providing publicly accessible information on the possible origins of a tag, it is also an important aid in preventing overlap that might occur between countries and projects.

Flipper tagging programmes and the data they yield can be used in combination with other tools, such as “TurtleNet”, an interactive atlas that shows nesting, courtship, feeding and migration routes of marine turtles.

Stakeholders involved in tagging programs in the IOSEA region are encouraged to provide details for inclusion in the table. For adding or updating the information, please contact the Secretariat at [email protected].