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Marine Biology

, Volume 156, Issue 12, pp 2621–2630 | Cite as

Habitat use by loggerhead sea turtles Caretta caretta off the coast of eastern Spain results in a high vulnerability to neritic fishing gear

  • Luis Cardona
  • Mónica RevellesEmail author
  • Mari Luz Parga
  • Jesús Tomás
  • Alex Aguilar
  • Ferran Alegre
  • Antonio Raga
  • Xavier Ferrer
Original Paper

Abstract

Previous studies of loggerhead sea turtles have concluded that drifting longlines were the main threat for immature specimens in the western Mediterranean, because immature loggerhead sea turtles mainly inhabit oceanic waters. However, recent aerial surveys have revealed large numbers of immature loggerhead sea turtles over the continental shelf of eastern mainland Spain, where turtles are exposed to neritic fishing gears but not to drifting longlines. We satellite-tracked seven loggerhead sea turtles (minimum straight carapace length (SCLmin) range: 36.5–55.0 cm) to assess whether the turtles in this region are vagrants from the adjoining oceanic regions or whether these loggerheads mostly inhabit the continental shelf. Satellite-tracking revealed that six of the tagged turtles avoided the oceanic realm and made extended use of the continental shelf, whereas only one individual could be considered a true vagrant as it avoided the continental shelf and primarily used the oceanic habitat. These results are in sharp contrast with those previously reported for immature loggerhead sea turtles of similar size from the south-western Mediterranean and fit well a relaxed ontogenic model that was recently proposed for loggerhead sea turtles in the central Mediterranean. Furthermore, these results demonstrate the vulnerability of loggerhead sea turtles of eastern mainland Spain to neritic fishing gears, as three of the seven turtles died and one was bycaught incidentally while being tracked over the continental shelf.

Keywords

Continental Shelf Argos Eastern Coast Swimming Behaviour Aerial Survey 

Notes

Acknowledgments

This project was partially financed by Capital Energy. The authors would like to thank the staff of Parc Natural del Delta de l’Ebre (Spain), Centro de Recuperación La Granja de el Saler of the Conselleria de Medio Ambiente, Urbanismo y Vivienda de la Generalitat Valenciana (Spain) and Le Seaquarium du Grau-du-Roi (France) for reporting the location of the stranded and bycaught turtles. J. Tomás is supported by a Marie Curie Postdoctoral Fellowship.

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Luis Cardona
    • 1
  • Mónica Revelles
    • 1
    Email author
  • Mari Luz Parga
    • 2
    • 3
  • Jesús Tomás
    • 4
  • Alex Aguilar
    • 1
  • Ferran Alegre
    • 2
  • Antonio Raga
    • 4
  • Xavier Ferrer
    • 1
  1. 1.Department of Animal Biology, Faculty of BiologyUniversity of BarcelonaBarcelonaSpain
  2. 2.Marine Animal Rescue Center (CRAM)Premià de MarSpain
  3. 3.BarcelonaSpain
  4. 4.Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary BiologyUniversity of ValenciaValenciaSpain

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