Persistent Leatherback Turtle Migrations Present Opportunities for Conservation

Abstract

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.

Route Fidelity during Marine Megafauna Migration

“…Empirical approaches, such as animal telemetry, can be used to develop and assess data-based models of animal movement, with the strongest models creating opportunities to inform conservation and management decision making with respect to both space and time. At a fundamental level, telemetry studies remain uniquely powerful ways to inform marine conservation through databased demonstrations of when and where marine megafauna are located across vast expanses of open-ocean (Shillinger et al, 2008;Gredzens et al, 2014;Maxwell et al, 2016;Dawson et al, 2017). Technological advances in animal telemetry, combined with advances in remote sensing (e.g., Figures S3-S8), have created unprecedented opportunities to retrospectively extract and analyse the geophysical and oceanographic conditions experienced by individual migrants during long-distance migration.…”

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…However, recent information from satellite tags have documented long travels between nesting beaches and foraging areas in the Atlantic and Pacific Ocean basins (Benson et al 2007a;Benson et al 2011;Eckert 2006a;Eckert et al 2006;Ferraroli et al 2004;Hays et al 2004;James et al 2005). Leatherbacks nesting in Central America and Mexico travel thousands of miles into tropical and temperate waters of the South Pacific (Eckert and Sarti 1997;Shillinger et al 2008). Data from satellite tagged leatherbacks suggest that they may be traveling in search of seasonal aggregations of jellyfish (Benson et al 2007b;Bowlby et al 1994;Graham 2009;Shenker 1984;Starbird et al 1993;Suchman and Brodeur 2005).…”

Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the U.S. and Bahamas

“…However, recent advances in remote monitoring devices, such as biotelemetry (satellite, radio and acoustic telemetry) and biologging (archival loggers) have revolutionized our capabilities for observation (Cooke et al, 2008), providing the tools to understand the causes and consequences of species' movement patterns and their underlying drivers, over ecologically meaningful spatial and temporal scales (Hussey et al, 2015). These data have resulted in conservation success stories; for example, strategies to reduce leatherback turtle (Dermochelys coriacea) fisheries interactions were developed from telemetry data (Shillinger et al, 2008). Using a behavioral representation of bluefin tuna (Thunnus thynnus) migration, Armsworth et al (2010) determined the economic efficiency of a time-area closure to protect spawning fish.…”