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


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.


Continental Shelf Argos Eastern Coast Swimming Behaviour Aerial Survey 



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.


  1. Aguilar R, Mas J, Pastor X (1995) Impact of the Spanish swordfish longline fisheries on the loggerhead sea turtle Caretta caretta population in the western Mediterranean. In: Richardson JI, Richardson TH (eds) Proceedings of the 12th Annual Workshop on Sea Turtle biology and Conservation. NOAA Tech Memo NMFS-SEFSC-361, pp 1–6Google Scholar
  2. Argos (2000) User’s manual. CLS, RamonvilleGoogle Scholar
  3. Avens L, Braun-McNeill J, Epperly S, Lohmann KJ (2003) Site fidelity and homing behavior in juvenile loggerhead sea turtles (Caretta caretta). Mar Biol 143:211–220CrossRefGoogle Scholar
  4. Báez JC, Real R, García-Soto C, de la Serna JM, Macías D, Camiñas JA (2007) Loggerhead turtle by-catch depends on distance to the coast, independent of fishing effort: implications for conservation and fisheries management. Mar Ecol Prog Ser 338:249–256CrossRefGoogle Scholar
  5. Balazs G, Miya R, Beavers S (1996) Procedures to attach a satellite transmitter to the carapace of an adult green turtle, Chelonia mydas. In: Keinath J, Barnard D, Musick J, Bell B (eds) Proceedings of the Fifteenth Annual Symposium on Sea Turtle Biology and Conservation. NOAA Tech Memo NMFS-SEFSC-367, pp 21–26Google Scholar
  6. Bentivegna F (2002) Intra-mediterranean migration of loggerhead sea turtles monitored by satellite telemetry. Mar Biol 141:795–800CrossRefGoogle Scholar
  7. Bertolero A (2003) Varamientos y capturas de tortugas marinas en los alrededores del Delta del Ebro (NE España) entre los años 1984 y 2001. Rev Esp Herpetol 17:39–54Google Scholar
  8. Bolten AB (2000) Técnicas para la medición de tortugas marinas. In: Eckert KL, Bjorndal KA, Abreu-Grobois FA, Donnelly M (eds) Técnicas de investigación y manejo para la conservación de las tortugas marinas, Grupo Especialista en Tortugas Marinas UICN/CSE Publication No 4, pp 126–131Google Scholar
  9. Broderick AC, Coyne MS, Fuller WJ, Glen F, Godley BJ (2007) Fidelity and over-wintering of sea turtles. Proc R Soc B 274:1533–1538CrossRefGoogle Scholar
  10. Camiñas JA, de la Serna JM (1995) The loggerhead distribution in the Western Mediterranean Sea as deduced from captures by the Spanish long line fishery. In: Llorente G, Montori A, Santos X, Carretero MA (eds) Scientia Herpetológica. Asociación Herpetológica Española, Barcelona, pp 316–323Google Scholar
  11. Camiñas JA, Báez JC, Valeiras Z, Real R (2006) Differential loggerhead by-catch and direct mortality due to surface longlines according to boat strata and gear type. Sci Mar 70:661–665CrossRefGoogle Scholar
  12. Cardona L, Revelles M, Carreras C, San Félix M, Gazo M, Aguilar A (2005) Western Mediterranean immature loggerhead turtles: habitat use in spring and summer assessed through satellite tracking and aerial surveys. Mar Biol 147:583–591CrossRefGoogle Scholar
  13. Carreras C, Cardona L, Aguilar A (2004) Incidental catch of loggerhead turtles Caretta caretta off the Balearic Islands (western Mediterranean). Biol Conserv 117:321–329CrossRefGoogle Scholar
  14. Carreras C, Pont S, Maffucci F, Pascual M, Barceló A, Bentivegna F, Cardona L, Alegre F, SanFélix M, Fernández G, Aguilar A (2006) Genetic structuring of immature loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea reflects water circulation patterns. Mar Biol 149:1269–1279CrossRefGoogle Scholar
  15. Casale P, Laurent L, De Metrio G (2004) Incidental capture of marine turtles by the Italian trawl fishery in the north Adriatic Sea. Biol Conserv 119:287–295CrossRefGoogle Scholar
  16. Casale P, Freggi D, Basso R, Vallini C, Argano R (2007) A model of area fidelity, nomadism, and distribution patterns of loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Mar Biol 152:1039–1049CrossRefGoogle Scholar
  17. Casale P, Abbate G, Freggi D, Conte N, Oliverio M, Argano R (2008) Foraging ecology of loggerhead sea turtles Caretta caretta in the central Mediterranean Sea: evidence for a relaxed life history model. Mar Ecol Prog Ser 372:265–276CrossRefGoogle Scholar
  18. Crowder LB (1990) Community ecology. In: Schreck CB, Moyle PB (eds) Methods for fish biology. American Fisheries Society, Bethesda, pp 609–632Google Scholar
  19. Deflorio M, Aprea A, Corriero A, Santamaría N, De Metrio G (2005) Incidental captures of sea turtles by swordfish and albacore longlines in the Ionina sea. Fish Sci 71:1010–1018CrossRefGoogle Scholar
  20. Dugger KM, Ballard G, Ainley DG, Barton KJ (2006) Effects of flipper bands on foraging behavior and survival of Adelie penguins (Pygoscelis adeliae). Auk 123:858–869CrossRefGoogle Scholar
  21. Eckert S, Moore JE, Dunn DC, Sagarminaga van Buiten R, Eckert KL, Halpin PN (2008) Modeling loggerhead turtle movement in the Mediterranean: importance of body size and oceanography. Ecol Appl 18:290–308CrossRefGoogle Scholar
  22. Estrada M (1996) Primary production in the northwestern Mediterranean. Sci Mar 60(suppl 2):55–64Google Scholar
  23. Gauthier-Clerc M, Gendner JP, Ribic CA, Fraser WR, Woehler EJ, Descamps S, Gilly C, Le Bohec C, Le Maho Y (2004) Long-term effects of flipper bands on penguins. Proc R Soc B 271:423–426CrossRefGoogle Scholar
  24. Godley BJ, Gücü AC, Broderick AC, Furness RW, Solomon SE (1998) Interaction between marine turtles and artisanal fisheries in the eastern Mediterranean: a probable cause for concern? Zool Middle East 16:48–64CrossRefGoogle Scholar
  25. Gómez de Segura A, Tomás J, Pedraza SN, Crespo EA, Raga JA (2003) Preliminary patterns of distribution and abundance of loggerhead sea turtles, Caretta caretta, around Columbretes Islands Marine Reserve, Spanish Mediterranean. Mar Biol 143:817–823CrossRefGoogle Scholar
  26. Gómez de Segura A, Tomás J, Pedraza SN, Crespo EA, Raga JA (2006) Abundance and distribution of the endangered loggerhead turtle in Spanish Mediterranean waters and the conservation implications. Anim Conserv 9:199–206CrossRefGoogle Scholar
  27. Hays GC, Äkesson B, Godley BJ, Luschi P, Santidrian P (2001) The implications of location accuracy for the interpretation of satellite-tracking data. Anim Behav 61:1035–1040CrossRefGoogle Scholar
  28. Hochscheid S, Bentivegna F, Bradai MN, Hays GC (2007) Overwintering behaviour in sea turtles: dormancy is optional. Mar Ecol Prog Ser 340:287–298CrossRefGoogle Scholar
  29. Ivlev VS (1961) Experimental ecology of the feeding of fishes. Yale University Press, New HavenGoogle Scholar
  30. Jribi I, Echwhiki K, Bradai MN, Bouain A (2008) Incidental capture of sea turtles by longlines in the Gulf of Gabès (South Tunisia): a comparative study between bottom and surface longlines. Sci Mar 72:337–342CrossRefGoogle Scholar
  31. Kareiva PM, Shigesada N (1983) Analysing insect movement as a correlated random walk. Oecologia 56:234–238CrossRefGoogle Scholar
  32. Lewison RK, Freeman SA, Crowder LR (2004) Quantifying the effects of fisheries on threatened species: the impact of pelagic longlines on loggerhead and leatherback sea turtles. Ecol Lett 7:221–231CrossRefGoogle Scholar
  33. Luschi P, Hays GC, Del Seppia C, Marsh R, Papi F (1998) The navigational feats of green sea turtles migrating from Ascension Island investigated by satellite telemetry. Proc R Soc Lond Ser B Biol Sci 265:2279–2284CrossRefGoogle Scholar
  34. Lutcavage ME, Lutz PL (1997) Diving physiology. In: Lutz PL, Musick JA (eds) The biology of sea turtles. CRC Press, Boca Raton, pp 387–410Google Scholar
  35. Margaritoulis D, Argano R, Baran I, Bentivegna F, Bradai MN, Camiñas JA, Casale P, De Metrio G, Demetropoulos A, Gerosa G, Godley BJ, Haddoud DA, Houghton J, Laurent L, Lazar B (2003) Loggerhead turtles in the Mediterranean sea: present knowledge and conservation perspectives. In: Bolten AB, Witherington BE (eds) Loggerhead sea turtles. Smithsonian Books, Washington, DC, pp 175–198Google Scholar
  36. Revelles M, Cardona L, Aguilar A, San Félix M, Fernández G (2007a) Habitat use by immature loggerhead sea turtles in the Algerian Basin (western Mediterranean): swimming behaviour, seasonality and dispersal pattern. Mar Biol 151:1501–1515CrossRefGoogle Scholar
  37. Revelles M, Isern-Fontanet J, Cardona L, San Félix M, Carreras C, Aguilar A (2007b) Mesoscale eddies, surface circulation and the scale of habitat selection by immature loggerhead sea turtles. J Exp Mar Biol Ecol 347:41–57CrossRefGoogle Scholar
  38. Revelles M, Cardona L, Aguilar A, Fernández G (2007c) The diet of pelagic loggerhead sea turtles (Caretta caretta) off the Balearic archipelago (western Mediterranean): relevance of long-line baits. J Mar Biol Assoc UK 87:805–813CrossRefGoogle Scholar
  39. Revelles M, Camiñas JA, Cardona L, Parga M, Tomás J, Aguilar A, Alegre F, Raga A, Bertolero A, Oliver G (2008) Tagging reveals limited exchange of immature loggerhead sea turtles (Caretta caretta) between regions in the western Mediterranean. Sci Mar 72:511–518CrossRefGoogle Scholar
  40. Smith WHF, Sandwell DT (1997) Global seafloor topography from satellite altimetry and ship depth soundings. Science 277:1957–1962Google Scholar
  41. Strauss RE (1979) Reliability estimates of Ivlev’s electivity index, the forage ratio, and a proposed linear index of food selection. Trans Am Fish Soc 111:517–522CrossRefGoogle Scholar
  42. Tomás J, Aznar FJ, Raga JA (2001) Feeding ecology of the loggerhead turtle Caretta caretta in the western Mediterranean. J Zool Soc Lond 255:525–532CrossRefGoogle Scholar
  43. Tomás J, Gozalbes P, Raga JA, Godley BJ (2008) Bycatch of loggerhead sea turtles: insights from 14 years of stranding data. Endang Species Res 5:161–169CrossRefGoogle Scholar
  44. Turchin P (1991) Translating foraging movements in heterogeneous environments into the spatial distribution of foragers. Ecology 72:1252–1266CrossRefGoogle Scholar
  45. Zar JH (1999) Biostatistical analysis. Prentice-Hall, Englewood CliffsGoogle Scholar

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

Personalised recommendations