Leatherback turtles round eddies

Image of the month - July 2004

The leatherback turtle is an endangered species. Its study should help protecting it, in particular by defining areas where it is most likely in interaction with fisheries -- fishing being one of the most critical threat on their survival.
Argos trackings of some turtles from their nesting beach in Guiana and Surinam give ideas on their paths. By overlaying those paths on altimetry sea surface heights, correlations can be tried between their behavior and ocean circulation. For example, it seems that they like warm eddies border, where currents accumulate their usual prey, jellyfishes.

Leatherback turtle path overlayed on absolute dynamic topography maps (MADT). This turtle went due North after leaving its nesting site in French Guiana, and then slowed down in the nutrient-rich front area between Gulf Stream and Labrador Current. On September 13, 2000 (above), this turtle is swiming at the eddies border (click on the map to see the animation, 1.2 Mb, or a higher résolution version, 3.9 Mb). (Credits CLS / CEPE/CNRS).

Leatherback turtle with an Argos beacon. Photo J.Y. Georges, CEPE/CNRS.

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References

  • Ferraroli S, Georges JY, Gaspar P, Le Maho Y, 2004: Where leatherback turtles meet fisheries. Nature 429: 521-522.