George L Shillinger 1 , Daniel M Palacios 2 , 3 , Helen Bailey 3 , Steven J Bograd 3 , Alan M Swithenbank 1 , Philippe Gaspar 4 , Bryan P Wallace 5 , James R Spotila 6 , Frank V Paladino 7 , Rotney Piedra 8 , Scott A Eckert 9 , Barbara A Block 1 , *
15 July 2008
Effective transboundary conservation of highly migratory marine animals requires international management cooperation as well as clear scientific information about habitat use by these species. Populations of leatherback turtles ( Dermochelys coriacea) in the eastern Pacific have declined by >90% during the past two decades, primarily due to unsustainable egg harvest and fisheries bycatch mortality. While research and conservation efforts on nesting beaches are ongoing, relatively little is known about this population of leatherbacks' oceanic habitat use and migration pathways. We present the largest multi-year (2004–2005, 2005–2006, and 2007) satellite tracking dataset (12,095 cumulative satellite tracking days) collected for leatherback turtles. Forty-six females were electronically tagged during three field seasons at Playa Grande, Costa Rica, the largest extant nesting colony in the eastern Pacific. After completing nesting, the turtles headed southward, traversing the dynamic equatorial currents with rapid, directed movements. In contrast to the highly varied dispersal patterns seen in many other sea turtle populations, leatherbacks from Playa Grande traveled within a persistent migration corridor from Costa Rica, past the equator, and into the South Pacific Gyre, a vast, low-energy, low-productivity region. We describe the predictable effects of ocean currents on a leatherback migration corridor and characterize long-distance movements by the turtles in the eastern South Pacific. These data from high seas habitats will also elucidate potential areas for mitigating fisheries bycatch interactions. These findings directly inform existing multinational conservation frameworks and provide immediate regions in the migration corridor where conservation can be implemented. We identify high seas locations for focusing future conservation efforts within the leatherback dispersal zone in the South Pacific Gyre.
Highly migratory marine animals routinely cross international borders during extensive migrations over thousands of kilometers, thus requiring conservation strategies with information about habitat use and movement patterns. Critically endangered leatherback turtles ( Dermochelys coriacea) in the eastern Pacific have suffered a severe population decline in recent years. In this study, we present the largest multi-year satellite tracking data set for leatherback turtles ( n = 46 turtles, 12,095 days) to describe the migrations, habitats, and dispersal of female leatherbacks tagged at Playa Grande, Costa Rica. Leatherbacks followed a migration corridor southward from Costa Rica into the South Pacific Gyre in each year of our study. In the equatorial region, leatherbacks experienced strong ocean currents that influenced the direction of their movements; leatherbacks responded to current deflection with rapid, directed movements to maintain their southward heading. After passing through this equatorial current field, turtles dispersed broadly within a low-energy, low-productivity region of the South Pacific. Our analyses revealed that ocean currents shaped the migration corridor and influenced the scope of turtle dispersal in the South Pacific—results that provide a biological rationale for the development of multi-scale conservation strategies. These strategies could involve improved and enhanced monitoring of leatherback–fisheries interactions as well as dynamic time-area fisheries closures and protected area designations within the high seas of the South Pacific.
Satellite tracking data from female leatherback turtles reveal their migration routes in the eastern Pacific and demonstrate how oceanic currents shape their migration corridors, providing a biological basis for conservation strategies.