Abstract
Understanding how sea turtles interact with their environment during their early oceanic life stages—the time often termed “Lost Years”—is critical for informing conservation strategies. This study provides the most comprehensive analysis to date of vertical diving behavior in early life stages of two sea turtles species: leatherback (Dermochelys coriacea) and loggerhead (Caretta caretta) sea turtles. Using over 2400 daily records from 71 individuals equipped with miniaturized satellite tags across multiple ocean basins, analyses revealed a clear ontogenetic progression. As a turtle’s size increases, they dive deeper and longer, with increasingly structured use of the water column. Some individuals also exhibited brief acclimatization phases after release, gradually adopting deeper and more consistent diving patterns. Environmental analyses highlight qualitative associations between vertical behavior in larger turtles and the structure of the water column, including thermal gradients and subsurface layers potentially associated with prey availability. These findings offer novel insights into the development, acclimatization, and ecological drivers of vertical movement in “Lost Years” sea turtles, helping to bridge knowledge gaps during this critical life stage.
Data availability
Restrictions apply to the availability of these data. Data were obtained from Upwell Turtles and are part of an ongoing collaborative research program involving multiple institutions. Due to ongoing analyses and planned publications, the full dataset is not publicly available at this stage. However, data are available upon reasonable request to the corresponding author and George L. Shillinger ([email protected] ), with permission from Upwell Turtles.
References
Hazen, E. L. et al. Ontogeny in marine tagging and tracking science: technologies and data gaps. Mar. Ecol. Prog Ser. 457, 221–240 (2012).
Shillinger, G. L. et al. Tagging through the stages: technical and ecological challenges in observing life histories through biologging. Mar. Ecol. Prog Ser. 457, 165–170 (2012).
Block, B. A. Physiological ecology in the 21st century: advancements in biologging science. Integr. Comp. Biol. 45, 305–320 (2005).
Spotila, J. R. et al. Worldwide population decline of Dermochelys coriacea: are leatherback turtles going extinct? Chelonian Conserv. Biol. 2, 209–222 (1996).
Mazaris, A. D., Broder, B. & Matsinos, Y. G. An individual based model of a sea turtle population to analyze effects of age dependent mortality. Ecol. Model. 198, 174–182 (2006).
Carr, A. Handbook of Turtles: The Turtles of the United States, Canada, and Baja California (Cornell University Press, 1952).
Mansfield, K. L. et al. Satellite tag attachment methods for tracking neonate sea turtles. Mar. Ecol. Prog Ser. 457, 181–192 (2012).
Mansfield, K. L., Wyneken, J., Porter, W. P. & Luo, J. First satellite tracks of neonate sea turtles redefine the ‘lost years’ oceanic niche. Proc. R. Soc. B Biol. Sci. 281, 20133039 (2014).
Mansfield, K. L. et al. First satellite tracks of South Atlantic sea turtle ‘lost years’: seasonal variation in trans-equatorial movement. Proc. R. Soc. B Biol. Sci. 284, 20171730 (2017).
Mansfield, K. L., Wyneken, J. & Luo, J. First Atlantic satellite tracks of ‘lost years’ green turtles support the importance of the Sargasso Sea as a sea turtle nursery. Proc. R. Soc. B 288, 20210057 (2021).
Barbour, N. et al. Satellite tracking of head-started juvenile green turtles (Chelonia mydas) reveals release effects and an ontogenetic shift. Animals 13, 1218 (2023).
Candela, T. et al. Novel microsatellite tags hold promise for illuminating the lost years in four sea turtle species. Animals 14, 903 (2024).
Barbour, N. et al. Environmental and biological factors influencing dispersal of neonate leatherback turtles (Dermochelys coriacea) from an endangered Costa Rican nesting population. Front. Mar. Sci. 7, 937 (2020).
Hoover, A. L., Shillinger, G. L., Williamson, S. A., Reina, R. D. & Bailey, H. Nearshore neonate dispersal of Atlantic leatherback turtles (Dermochelys coriacea) from a non-recovering subpopulation. Sci. Rep. 10, 18748 (2020).
Wallace, B. P. et al. Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities. Ecosphere 4, 1–49 (2013).
Swimmer, Y. et al. Sea turtle bycatch mitigation in US longline fisheries. Front. Mar. Sci. 4, 260 (2017).
Báez, J. C., García-Barcelona, S., Camiñas, J. A. & Macías, D. Fishery strategy affects the loggerhead sea turtle mortality trend due to the longline bycatch. Fish. Res. 212, 21–28 (2019).
Barbour, N. et al. Incorporating multidimensional behavior into a risk management tool for a critically endangered and migratory species. Conserv. Biol. 37, e14114 (2023).
Barbour, N. et al. Clustering and classification of vertical movement profiles for ecological inference of behavior. Ecosphere 14, e4384 (2023).
Casale, P. & Tucker, A. D. Caretta caretta. The IUCN Red List of Threatened Species. (2017). .
Wallace, B., Tiwari, M. & Girondot, M. Dermochelys coriacea. The IUCN Red List of Threatened Species. https://doi.org/10.2305/IUCN.UK.2013-2.RLTS.T6494A43526147.en (2013).
Kanghae, H. et al. First successful head-start program of leatherback sea turtles (Dermochelys coriacea) in Thailand and proposed dietary strategy. Zoo Biol. 43, 110–122 (2023).
Jones, T. T., Hastings, M. D., Bostrom, B. L., Pauly, D. & Jones, D. R. Growth of captive leatherback turtles, Dermochelys coriacea, with inferences on growth in the wild: Implications for population decline and recovery. J. Exp. Mar. Biol. Ecol. 399, 84–92 (2011).
Ramirez, M. D., Popovska, T. & Babcock, E. A. Global synthesis of sea turtle von Bertalanffy growth parameters through Bayesian hierarchical modeling. Mar. Ecol. Prog Ser. 657, 191–207 (2021).
Murray, D. L. & Fuller, M. R. A critical review of the effects of marking on the biology of vertebrates. Res Tech. Anim. Ecol. Controv Consequences 15–64 (2000).
Kenward, R. A manual for wildlife radio tagging: behaviour and home ranges. Man Wildl. Radio Tagging 201–232 (2001).
Vandenabeele, S. P., Shepard, E. L., Grogan, A. & Wilson, R. P. When three per cent may not be three per cent; device-equipped seabirds experience variable flight constraints. Mar. Biol. 159, 1–14 (2012).
Altman, D., Machin, D., Bryant, T. & Gardner, M. Statistics with Confidence: Confidence Intervals and Statistical Guidelines (Wiley, 2013).
Jonsen, I. D. et al. aniMotum, an R package for animal movement data: rapid quality control, behavioural estimation and simulation. Methods Ecol. Evol. 14, 806–816 (2023).
E.U. Copernicus Marine Service Information (CMEMS). Global Ocean Physics Analysis and Forecast. https://doi.org/10.48670/moi-00016
E.U. Copernicus Marine Service Information (CMEMS). Global Ocean Waves Analysis and Forecast. https://doi.org/10.48670/moi-00017
E.U. Copernicus Marine Service Information (CMEMS). Global Ocean Biogeochemistry Analysis and Forecast. https://doi.org/10.48670/moi-00015
Ardhuin, F. et al. Semi-empirical dissipation source functions for wind-wave models: part i, definition, calibration and validation at global scales. J. Phys. Ocean. 40, 1917–1941 (2010).
Janssen, P. et al. Final report of work package I in my wave project. Cited On 17 (2014).
Jakobsson, M. Global bathymetric data sets-general bathymetric chart of the oceans (GEBCO). Boll Geofis 195, (2016).
R Core Team. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-Proj.Org (2022).
Wood, S. N. Fast stable restricted maximum likelihood and marginal likelihood estimation of semiparametric generalized linear models. J. R Stat. Soc. Ser. B Stat. Methodol. 73, 3–36 (2011).
Deraniyagala, P. Some postnatal changes in the leathery turtle, Dermochelys coriacea. Ceylon J. Sci. 19, 225–239 (1936).
K Milsom, W. Development of buoyancy control in juvenile Atlantic loggerhead turtles, Caretta c. caretta. Copeia 1975, 758–762 (1975).
Lutcavage, M. E., Bushnell, P. G. & Jones, D. R. Oxygen transport in the leatherback sea turtle Dermochelys coriacea. Physiol. Zool. 63, 1012–1024 (1990).
Paladino, F., Spotila, J., O’Connor, M. & Gatten, R. Jr. Respiratory physiology of adult leatherback turtles (Dermochelys coriacea) while nesting on land. Chelonian Conserv. Biol. 2, 223–229 (1996).
Lutcavage, M. E. & Lutz, P. L. Diving physiology. in The Biology of Sea Turtles, Vol I 277–296 (CRC, 1997).
Hochscheid, S., Bentivegna, F. & Speakman, J. R. The dual function of the lung in chelonian sea turtles: buoyancy control and oxygen storage. J. Exp. Mar. Biol. Ecol. 297, 123–140 (2003).
Lutcavage, M. E. & Lutz, P. L. Voluntary diving metabolism and ventilation in the loggerhead sea turtle. J. Exp. Mar. Biol. Ecol. 147, 287–296 (1991).
Salmon, M., Jones, T. T. & Horch, K. W. Ontogeny of diving and feeding behavior in juvenile seaturtles: leatherback seaturtles (Dermochelys coriacea L.) and green seaturtles (Chelonia mydas L.) in the Florida current. J. Herpetol. 38, 36–43 (2004).
Robinson, N. & Paladino, F. Diving behavior and physiology of the leatherback turtle. Leatherback Turt 21–31 (2015).
Howell, E. A. et al. Oceanographic influences on the dive behavior of juvenile loggerhead turtles (Caretta caretta) in the North Pacific Ocean. Mar. Biol. 157, 1011–1026 (2010).
Chambault, P. et al. Swirling in the ocean: immature loggerhead turtles seasonally target old anticyclonic eddies at the fringe of the North Atlantic gyre. Prog Oceanogr. 175, 345–358 (2019).
Polovina, J. J., Howell, E., Parker, D. M. & Balazs, G. H. Dive-depth distribution of loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) sea turtles in the central North Pacific: might deep longline sets catch fewer turtles? (2003).
Hochscheid, S. Why we mind sea turtles’ underwater business: a review on the study of diving behavior. J. Exp. Mar. Biol. Ecol. 450, 118–136 (2014).
Fujita, K. et al. Polymorphic foraging tactics in a marine reptile: insight from horizontal movement and dive behavior analyses. Mar. Ecol. Prog Ser. 707, 115–129 (2023).
Stokes, K. L. et al. Optimization of swim depth across diverse taxa during horizontal travel. Proc. Natl. Acad. Sci. 121, e2413768121 (2024).
Davenport, J. et al. Ontogenetic changes in tracheal structure facilitate deep dives and cold water foraging in adult leatherback sea turtles. J. Exp. Biol. 212, 3440–3447 (2009).
Davenport, J., Jones, T. T., Work, T. M. & Balazs, G. H. Unique characteristics of the trachea of the juvenile leatherback turtle facilitate feeding, diving and endothermy. J. Exp. Mar. Biol. Ecol. 450, 40–46 (2014).
Kooyman, G. L. Weddell Seal, Consummate Diver. (1981).
Limpus, C. A benthic feeding record from neritic waters for the leathery turtle (Dermochelys coriacea). Copeia 552–553 (1984).
Eckert, S. A., Nellis, D. W., Eckert, K. L. & Kooyman, G. L. Diving patterns of two leatherback sea turtles (Dermochelys coriacea) during internesting intervals at Sandy Point, St. Croix, US Virgin Islands. Herpetologica 381–388 (1986).
Eckert, S. A., Eckert, K. L., Ponganis, P. & Kooyman, G. Diving and foraging behavior of leatherback sea turtles (Dermochelys coriacea). Can. J. Zool. 67, 2834–2840 (1989).
Grant, G. & Ferrell, D. Leatherback turtle, Dermochelys coriacea (Reptilia: Dermochelidae): notes on the near-shore feeding behavior and association with cobia. Brimleyana 77–81 (1993).
Grant, G., Malpass, H. & Beasley, J. Correlation of leatherback turtle and jellyfisch occurrence. Herpetol Rev. 27, 123–125 (1996).
Houghton, J. D., Doyle, T. K., Davenport, J., Wilson, R. P. & Hays, G. C. The role of infrequent and extraordinary deep dives in leatherback turtles (Dermochelys coriacea). J. Exp. Biol. 211, 2566–2575 (2008).
Manning, J. C., Rosengarten, S., Hooper, C. & Fuentes, M. M. P. B. Post-release changes in the fine-scale diving behavior and activity of loggerhead sea turtles (Caretta caretta) from the Northeastern Gulf of Mexico. Anim. Biotelemetry. 13, 13 (2025).
Sakamoto, W. et al. Deep diving behavior of the loggerhead turtle near the frontal zone. Nippon Suisan Gakkaishi. 56, 1435–1443 (1990).
Hays, G. C. et al. The diving behaviour of green turtles at Ascension Island. Anim. Behav. 59, 577–586 (2000).
Hochscheid, S., Bentivegna, F. & Hays, G. C. First records of dive durations for a hibernating sea turtle. Biol. Lett. 1, 82–86 (2005).
Saba, V. S. et al. An oceanographic context for the foraging ecology of Eastern Pacific leatherback turtles: consequences of ENSO. Deep Sea Res. Part. Oceanogr. Res. Pap. 55, 646–660 (2008).
Shillinger, G. L. et al. Persistent leatherback turtle migrations present opportunities for conservation. PLoS Biol. 6, e171 (2008).
Shillinger, G. et al. Identification of high-use internesting habitats for eastern Pacific leatherback turtles: role of the environment and implications for conservation. Endanger. Species Res. 10, 215–232 (2010).
Shillinger, G. L. et al. Vertical and horizontal habitat preferences of post-nesting leatherback turtles in the South Pacific Ocean. Mar. Ecol. Prog Ser. 422, 275–289 (2011).
Heithaus, M. R. Predators, prey, and the ecological roles of sea turtles. in The biology of sea turtles vol. 3 249CRC Press, (2013).
Willis-Norton, E. et al. Climate change impacts on leatherback turtle pelagic habitat in the Southeast Pacific. Deep Sea Res. Part. II Top. Stud. Oceanogr. 113, 260–267 (2015).
Okuyama, J., Benson, S. R., Dutton, P. H. & Seminoff, J. A. Changes in dive patterns of leatherback turtles with sea surface temperature and potential foraging habitats. Ecosphere 12, e03365 (2021).
Howell, E. A., Kobayashi, D. R., Parker, D. M., Balazs, G. H. & Polovina, J. J. TurtleWatch: a tool to aid in the bycatch reduction of loggerhead turtles Caretta caretta in the Hawaii-based pelagic longline fishery. Endanger. Species Res. 5, 267–278 (2008).
Abecassis, M. et al. A model of loggerhead sea turtle (Caretta caretta) habitat and movement in the oceanic North Pacific. PLoS One. 8, e73274 (2013).
Gaspar, P. & Lalire, M. A model for simulating the active dispersal of juvenile sea turtles with a case study on western Pacific leatherback turtles. PLoS One. 12, e0181595 (2017).
Backus, R. H. & Clarke, G. L. Interrelations between the Vertical Migration of Deep Scattering Layers, Biolluminescence, and Changes in Daylight in the Sea. (1964).
Alvarez, I. et al. Influence of the seasonal thermocline on the vertical distribution of larval fish assemblages associated with Atlantic Bluefin Tuna Spawning Grounds. Oceans 2, 64–83 (2021).
Chamberlin, D., Shaw, R. & Rich, A. The seasons and the thermoclines. Our World Ocean: Understanding the Most Important Ecosystem on Earth—Essentials Edition (2023). https://geo.libretexts.org/Bookshelves/Oceanography/Our_World_Ocean%3A_Understanding_the_Most_Important_Ecosystem_on_Earth_Essentials_Edition_%28Chamberlin_Shaw_and_Rich%29/03%3A_Voyage_III_Ocean_Physics/11%3A_The_Seasons_of_the_Sea/11.07%3A_The_Seasons_and_the_Thermoclines
Romero, E., Tenorio-Fernandez, L., Portela, E. & Montes-Aréchiga, J., Sánchez-Velasco, L. Improving the thermocline calculation over the global ocean. Ocean. Sci. 19, 887–901 (2023).
Acknowledgements
This study was financially and kindly supported by Upwell Turtles, Mercator Ocean International and the Copernicus Marine Service of the European Union, and Aquarium La Rochelle. The authors would like to acknowledge the whole Upwell team and board of directors, in particular Dr. K. Reed for her invaluable operational support, K. Fisher for her administrative and programmatic support, and K. Sargent for her media and outreach support. The Florida-based team acknowledges the essential assistance of S. Antenoff, C. Bennice, E. Edds, E. Schulteis, and S. Trail for leatherback husbandry. We also would like to thank the South African Association for Marine Biological Research (SAAMBR) for logistical support, including facilities and transportation, and iSimangaliso Wetland Park Authority for permission to conduct turtle release activities within a protected marine reserve and World Heritage Site. The Aquarium La Rochelle team would like to acknowledge the volunteer correspondents of the East Atlantic Sea Turtle Network coordinated by the Aquarium La Rochelle who work in the field, participate in rescue operations and bring sea turtles to the CESTM for treatment and for data collection. The Azores team would like to acknowledge the invaluable help of its partners: whale watching companies, fishers, Flying Sharks and the regional stranding network RACA (Rede de Arrojamento de Cetáceos dos Açores). The authors also acknowledge M. Authier for his useful advice on the statistical analysis of the tracking data.
Funding
T.C. was financially supported by Upwell Turtles, Mercator Ocean International and the Copernicus Marine Service of the European Union, and Aquarium La Rochelle. Work in the Azores was developed by the COSTA (COnsolidating Sea Turtle conservation in the Azores, costaproject.org) project funded by the Marine Turtle Conservation Fund of the U.S. Fish and Wildlife Service (Agreement number F21AP02724), the Archie Carr Center for Sea Turtle Research through support from the Disney Conservation Fund, and the Regional Directorate for Fisheries (DRP), and the LIFE IP Azores Natura project (LIFE17IPE/PT/000010) funded by the European Commission. F.V. was supported by the Investigator Programme of the Fundação para a Ciência e Tecnologia (FCT CEECIND/03426/2020). IICM Okeanos acknowledges support from FCT – Foundation for Science and Technology, I.P., under the project UIDB/05634/2025 and UIDP/05634/2025 and through the Regional Government of the Azores through the project M1.1.A/FUNC.UI&D/003/2021–2024 and the project M1.1.A/REEQ.CIENTÍFICO UI&D/2021/010.
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T.C., P.G., and G.L.S. conceived the study. T.C., J.W., E.T., T.N.T., R.N., H.K., P.S., T.U., J.O., I.K., K.Ma., K.Mi., N.O., F.V., A.M.F., A.H., M.D.B., F.D.A., A.N., J.N., I.G., and G.L.S. conducted fieldwork including animal care, tag attachment and sea turtle release. G.L.S., P.G., and T.C. designed field tracking experiments in collaboration with local and regional teams from coauthor institutions. T.C. and G.L.S. acquired the sea turtle tracking data. T.C. processed sea turtle tracking data with input from coauthors regarding turtle metadata and release information. H.B. ran statistical models and performed associated analyses. T.C. and P.G. performed the joint analysis of sea turtle tracking data and operational oceanography products. T.C. developed and ran all Python software tools needed for analysis and data visualization. T.C. wrote the initial draft of the manuscript with support from P.G., G.L.S., J.W., E.T., F.D.A., and H.B. All authors contributed to the paper revision. All authors read and approved the final manuscript.
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Candela, T., Gaspar, P., Bailey, H. et al. Pioneering insights into the diving behavior of early-stage sea turtles revealed by novel marine miniaturized satellite tags.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-47239-6
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DOI: https://doi.org/10.1038/s41598-026-47239-6
Keywords
- Juvenile sea turtles
- Vertical behavior
- Diving activity
- Miniaturized satellite tags
- Foraging strategy
- Migration
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