From time to time, new technologies emerge that can play an important role in the study and protection of nature and endangered species. One of these is telemetry, i.e. the automatic measurement and wireless transmission of data from remote sources. The advantage of telemetry is that it provides information through the “eyes” of the animals themselves like data about their movements and their preferences in habitats, avoiding the limitations of typical research designs.

ARCHELON, in its long history since its establishment in 1983, has been using new technologies in order to carry out its multifaceted work. It was thus one of the first organizations in Greece to use satellite transmitters in the study of protected species.

Satellite transmitters are small, waterproof devices that are usually attached to the turtle's shell with a special adhesive. Each time the turtle rises to the surface to breathe, a "switch" activates the long-lasting battery and the transmitter sends a signal to one of Argos satellites orbiting the earth. This signal is then transmitted to ARCHELON's computers, indicating the turtle's location and, in a short time, a map is created showing the turtle's entire path. In 2-3 years, when the battery has been exhausted, the transmitter detaches from the turtle's shell.

The first satellite transmitters were placed in 2002 on turtles in the Amvrakikos Gulf. Since then, ARCHELON and its partners have placed 150 satellite and GSM tags on sea turtles in various areas of Greece. These transmitters ranged from simple ones to advanced models that, in addition to position, record depth and temperature. The transmitters have been placed on adult and juvenile, male and female Loggerhead turtles (Caretta caretta), except for one transmitter that wasfitted on a green turtle (Chelonia mydas) in Syria. “We prepared a small Feature on ARCHELON's satellite monitoring of 150 sea turtles through the years, to highlight our results” says Aliki Panagopoulou (PhD), Head of Research Activities at ARCHELON.

The results so far have led to important conclusions regarding the migrations and ecology of the Loggerhead in Greece, with the ultimate goal of its more substantial protection at a Mediterranean level. Some of these conclusions are:

• Important feeding areas for turtles that lay eggs in Zakynthos and Kyparissia Bay are the Adriatic Sea and the Gulf of Gabès in Tunisia.
• The turtles of Rethymno, between successive nestings, can move up to 150 km. from the initial nesting beach, and possibly lay eggs on another beach.
• The turtles of Rethymno, after their breeding season, migrate to the Gulf of Gabès (Tunisia) and the Aegean Sea, but not to the Adriatic (like the turtles of Zakynthos and Kyparissia).
• The turtle "Regina" in 2013 made the largest migration ever recorded in Greece, from Messolonghi to Ibiza, Spain!
• Turtles do not necessarily "settle" in a specific feeding area, as we thought, but can also live in the open sea, feeding on pelagic organisms!
• The average nesting frequency (i.e. the number of nests that each turtle makes during the nesting season) is higher than we assumed!

At the 9th Our Ocean Conference in April 2024, Greece committed to installing 200 new satellite transmitters to monitor sea turtles. In the summer of 2024, as part of the LIFE MareNatura project, ARCHELON installed satellite tags on 20 turtles in various nesting areas. Also, in November 2024, with the support of the TUI Care Foundation, we installed a satellite transmitter on a turtle that was released after treatment at the ARCHELON Rescue Centre.

Learn more in the special Feature!

Follow the 2024 turtle journeys live on our website!