Journal of Experimental Marine Biology and Ecology
The 7000-km oceanic journey of a leatherback turtle tracked by satellite
Introduction
The leatherback, Dermochelys coriacea, is a highly pelagic, cosmopolitan turtle whose behaviour has been mostly studied with observations in its nesting areas (see references in Rostal et al., 1996). Recoveries of tagged individuals have shown that this species undertakes long journeys – for instance crossing the Atlantic Ocean – and in some cases reaches cold seas far away from their tropical nesting beaches (Bleakney, 1965, Pritchard, 1976, Boulon et al., 1988). Satellite tracking techniques have permitted partial reconstructions of straight migration courses as long as 2800 km (Duron-Dufrenne, 1987, Morreale et al., 1996) and contributed to the collection of information for the development of conservation strategies, which are urgently required to protect this endangered species (Spotila et al., 1996).
In this paper, we describe the movements of a leatherback tracked for 124 days for more than 7000 km. Besides internesting wanderings and straight transfers into new areas, we also recorded movements which appear to reflect feeding activities, as is expected for a predator living on pelagic invertebrates with a low caloric value (Lutcavage and Lutz, 1986, Bjorndal, 1997).
Section snippets
Materials and methods
The turtle we tracked was an adult female nesting on the Maputaland Marine Reserve, northern KwaZulu-Natal, South Africa (tag no. EE309, curved carapace length 1630 mm). She was found on the night of Jan. 15, 1996, while laying eggs in the most northern part of the reserve (27°02' S, 32°52'E). After nesting, she was equipped with a Telonics Inc. (Mesa, AZ, USA) ST-14 satellite transmitter linked to the Argos system (Taillade, 1993). The transmitter (platform transmitter terminal, PTT) was held
Results
The course followed by the turtle is given in Fig. 1. The reader can evaluate the degree of approximation of the track by looking at Fig. 2, where two parts of the course are magnified and plotted along with all the relative fixes. After release, the turtle wandered in the coastal waters south of the capture site for nine days, swimming in a circuitous route for 404 km (leg 1). On Jan. 25, she left the area in a northern direction but three days later she headed first SSE and then SW (legs
Discussion
Previous recoveries of leatherbacks tagged in Maputaland were from the Western Indian Ocean up to 2500 km away from the nesting beach (Hughes, 1989, Hughes, 1996). As none of them had occurred south of 30°S, the journey of our leatherback as far away as the Southern Ocean was totally unexpected. The very first part of our recordings shows wandering movements in the waters around the nesting area for a total length of 400 km (leg 1). They are to be interpreted as internesting activity: first,
Acknowledgements
We thank the Natal Parks Board, KwaZulu-Natal and especially Mr and Mrs Warren Bartholomew, M. Burningham, P. Mealin and Nelson at Boteler Point. This research was supported by the Italian MURST, the ENEA and the Accademia Nazionale dei Lincei.
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