Satellite tracking of sea turtles released after prolonged captivity periods

Abstract

Rehabilitation is an important part of sea turtle conservation, and post-release tracking of the animals is both a way of obtaining information on their movements and behaviour and, at least temporarily, monitoring the success of the rehabilitation process. Two green turtles, Chelonia mydas, and one loggerhead turtle, Caretta caretta, were rehabilitated after long periods in captivity, and their movements followed by satellite tracking after their release near the south of Portugal. Location data were obtained for an average of 688 days after release. All three animals showed a directional movement and the last observed locations coincided with known feeding areas for both species, near the coasts of Mauritania and the state of Ceará, Brazil, for the green turtles, and near Cuba for the loggerhead. Bathymetry, surface currents, wind, sea surface temperature, chlorophyll-a concentration and geomagnetic field were analysed as spatial and environmental variables potentially affecting movement. Only bathymetry, sea surface temperature and geomagnetic variables showed significant association with the path choice. This project supports the notion that sea turtles have the ability to survive in the wild after long periods in captivity and to return to the species' known feeding areas, justifying the effort in their rehabilitation and post-release tracking.

Key words:

• Atlantic Ocean
• Caretta caretta
• Chelonia mydas
• sea turtle rehabilitation

Acknowledgements

Élio Vicente of Zoomarine Portugal was instrumental to this study in many ways. We are grateful to the Portuguese Navy for their continuous collaboration in turtle release operations. We thank Michael Coyne (seaturtle.org) for help in data collection, Paulo Relvas (Centro de Ciências do Mar, Facultade de Ciências e Tecnologia, University of the Algarve) for assistance in the interpretation and treatment of some variables, and José Matos (Instituto Nacional de Investigação Agrária e Veterinária, IP) for his very useful comments on the manuscript. Carla Flanagan and Rebecca Hale (Zoomarine) kindly revised the English and Miguel Silveira (Zoomarine) contributed with very useful comments and support.

Funding

The administration board of Zoomarine Portugal funded the spatial analysis.

Editorial responsibility: Leandro Bugoni

Additional information

Funding

Funding: The administration board of Zoomarine Portugal funded the spatial analysis.