Large-scale movements and high-use areas of western Pacific leatherback turtles,Dermochelys coriacea

Abstract

Abstract. The western Pacific leatherback turtle (Dermochelys coriacea), one of three genetically distinct stocks in the Indo-Pacific region, has declined markedly during past decades. This metapopulation nests year-round at beaches of several western Pacific island nations and has been documented through genetic analysis and telemetry studies to occur in multiple regions of the Pacific Ocean. To provide a large-scale perspective of their movements, high-use areas, and habitat associations, we report and synthesize results of 126 satellite telemetry deployments conducted on leatherbacks at western Pacific nesting beaches and at one eastern Pacific foraging ground during [2000][2001][2002][2003][2004][2005][2006][2007]. A Bayesian switching state-space model was applied to raw Argos-acquired surface locations to estimate daily positions and behavioral mode (either transiting or area-restricted search) for each turtle. Monthly areas of high use were identified for postnesting periods using kernel density estimation. There was a clear separation of migratory destinations for boreal summer vs. boreal winter nesters. Leatherbacks that nested during boreal summer moved into Large Marine Ecosystems (LMEs) of the temperate North Pacific Ocean or into tropical waters of the South China Sea. Turtles that nested during boreal winter moved into temperate and tropical LMEs of the southern hemisphere. Area-restricted search occurred in temperate and tropical waters at diverse pelagic and coastal regions exhibiting a wide range of oceanographic features, including mesoscale eddies, coastal retention areas, current boundaries, or stationary fronts, all of which are known mechanisms for aggregating leatherback prey. Use of the most distant and temperate foraging ground, the California Current LME, required a 10-12 month trans-Pacific migration and commonly involved multiple years of migrating between high-latitude summer foraging grounds and low-latitude eastern tropical Pacific wintering areas without returning to western Pacific nesting beaches. In contrast, tropical foraging destinations were reached within 5-7 months and appeared to support year-round foraging, potentially allowing a more rapid return to nesting beaches. Based on these observations, we hypothesize that demographic differences are likely among nesting females using different LMEs of the Indo-Pacific. The differences in movements and foraging strategies underscore the importance of and the need for ecosystem-based management and coordinated Pacific-wide conservation efforts. v www.esajournals.org 1

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

“…These adaptations allow leatherbacks to be comfortable in a wide range of temperatures and to travel further than any other sea turtle species (NMFS and USFWS 1995). For example, a leatherback may swim more than 6,000 miles (10,000 km) in a single year (Benson et al 2007a;Benson et al 2011;Eckert 12 Countercurrent circulation is a highly efficient means of minimizing heat loss through the skin's surface because heat is recycled. For example, a countercurrent circulation system often has an artery containing warm blood from the heart surrounded by a bundle of veins containing cool blood from the body surface.…”

“…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).…”

Oceanic dispersal of juvenile leatherback turtles: going beyond passive drift modeling

“…8), with the only exception being the Sulu Sea and the adjacent southern part of the South China Sea. This area is visited by only 2% of the simulated Jamursba-Medi juveniles, while it was actually exploited by 13 out of 37 adults tracked by Benson et al (2011). However, the Sulu Sea is separated from much more frequented areas of the North Pacific and Sulawesi Sea by the complex Philippine and Sulu archipelagos, and horizontal resolution of the G1 model only allows a crude and incomplete representation of the many small passages that exist throughout these archipelagos.…”

Bahamas connection: residence areas selected by breeding female loggerheads tagged in Dry Tortugas National Park, USA

“…core areas] within a home-range boundary, see [53][54][55]), SSM has been suggested as a way to enhance analysis of Argos tracking data sets [56]. SSM was recently used to delineate foraging zones for post-nesting Kemp's ridleys in the GoM [4], define the migrations and foraging areas for leatherback turtles nesting in the Pacific Ocean [47,57], determine foraging areas for juvenile green turtles in the SW Atlantic [58], and describe residence or foraging areas in the GoM for female loggerheads from three separate subpopulations [3].…”