Satellite telemetry techniques now offer the opportunity to track marine turtles during their migrations. The easiest way to do that is to deploy satellite transmitters on nesting females which can be easily approached while laying eggs on tropical and subtropical beaches.
In this way, the turtles’ post-nesting migrations can be reconstructed, permitting to identify the localizations of their residential foraging grounds, where they will remain for 1-3 years until they are ready to breed again. In some (rare) cases, tag duration extends so much to allow the tracking of the pre-breeding migration from the foraging grounds to the nesting beach.
Upon completing their nesting cycle, consisting in several (generally 2-8) egg-laying events, female turtles quickly start their postnesting migrations towards their foraging grounds, which often are individually-specific sites that are located hundreds or even thousands of km away from nesting area. Instrumented turtles can then be localised in several ways, e.g. by GPS and/or through the Argos System, a widespread technique used to study sea turtle movements and general at-sea behaviour. To learn more about how the Argos System works click here or here.
Since 1993, our research group has tracked the long-distance migrations of a number of adult turtles nesting in different parts of the world, and belonging to three species: the green (Chelonia mydas), the leatherback (Dermochelys coriacea) and the loggerhead (Caretta caretta) turtle.
In the following, examples the routes reconstructed in this way are shown, along with the collaborators involved in each study and the main scientific papers resulting.
1. Green sea turtles (Chelonia mydas) nesting at Redang Island, peninsular Malaysia.
The study was performed in collaboration with Drs. Liew Hoch Chark and Eng Heng Chan of Pertanian University, Terengganu and is described in the paper Luschi et al. 1996, J. Comp. Physiol. 178: 447-452.
2. Loggerhead sea turtles (Caretta caretta) nesting in Maputaland, South Africa
The study was performed in collaboration with Dr George Hughes of KwaZulu Natal Nature Conservation and is described in the paper Papi et al. 1997, Mar. Biol. 129: 215-220.
3. Green turtles nesting at Ascension Island, South Atlantic Ocean
Our research group has been the first to track the epic migrations the green turtles that nest at Ascension Island in the middle of the Atlantic Ocean, which represents a paradigmatic case of a long-distance migrant in the oceanic environment. The study was possible thanks to a long-lasting collaboration with Graeme Hays and coworkers at Swansea University (UK).
Several papers derived from these experiments:
Luschi et al. 1998, Proc. R. Soc. Lond. B 265: 2279-2284;
Papi et al. 2000, J. Exp. Biol. 203: 3435-3443;
Hays et al. 2001, Int. J. Remote Sens. 22: 1403-1411.
4. Leatherback turtles (Dermochelys coriacea) nesting in Maputaland, South Africa
Leatherback turtles are known to be pelagic, cosmopolitan turtles which leave the coastal nesting areas to reach the oceanic environment where they forage and perform wandering movements over huge offshore areas. This study was performed in collaboration with Dr George Hughes of KwaZulu-Natal Nature Conservation and is reported in a series of papers:
Hughes et al. 1998, J. Exp. Mar. Biol. Ecol. 229: 209-217;
Luschi et al. 2003, Proc. R. Soc. Lond. B 270 Suppl. 2: 129-132;
Luschi et al. 2006, S. Afr. J. Sci. 102: 51-58.
4. Loggerhead turtles nesting in Calabria, southern Italy
To be added soon…