Post-nesting movements of 12 green turtles from the Galápagos Islands (Ecuador) were tracked with satellite telemetry during the 2003 and 2005 nesting seasons. To illuminate potential environmental influences on turtle movements we compared tracks with a variety of remotely sensed oceanographic variables including sea surface temperature (SST), SST front probability, surface height anomaly, surface current, and surface chlorophyll a concentration. Three distinct post-nesting migratory strategies were observed, including oceanic migration to Central America (Type A1 move- ments, n = 3), residency within the Galápagos (Type A2 movements, n = 2), and movement into oceanic waters southwest of the Galápagos (Type B movements, n = 7). Two turtles migrating to Central Amer- ica reached neritic foraging areas in Nicaragua and Panama that were 1500 and 1542 km, respectively, from their nesting sites, and one resident turtle established a foraging home range 75 km from its final nesting site. Oceanic movements occurred in waters with a mean SST of 26.5°C and mean surface chlorophyll a concentration of 0.18 mg m -3 , whereas neritic movements were in waters with a mean SST of 24.3°C and mean surface chlorophyll a concentration of 0.47 mg m -3 . All turtles accessed SST frontal zones at a greater rate than their availability, and at least 2 turtles conducted movements in the oceanic zone that were indicative of foraging activity. This is the first report of migratory corridors for Galápagos green turtles, confirming prior flipper tagging data that show that the Galápagos is a source rookery for green turtles in coastal areas of Central America. The high proportion of green tur- tles departing the Galápagos (83%) indicates that marine fisheries bycatch and directed hunting on this stock outside the Galápagos may impact this population more than previously believed, and underscores the need for multi-national conservation efforts that combat these threats.

Effective conservation strategies for highly migratory species must incorporate information about long-distance movements and locations of high-use foraging areas. However, the inherent challenges of directly monitoring these factors call for creative research approaches and innovative application of existing tools. Highly migratory marine species, such as marine turtles, regularly travel hundreds or thousands of kilometers between breeding and feeding areas, but identification of migratory routes and habitat use patterns remains elusive. Here we use satellite telemetry in combination with compound-specific isotope analysis of amino acids to confirm that insights from bulk tissue stable isotope analysis can reveal divergent migratory strategies and within-population segregation of foraging groups of critically endangered leatherback sea turtles (Dermochelys coriacea) across the Pacific Ocean. Among the 78 turtles studied, we found a distinct dichotomy in δ¹⁵N values of bulk skin, with distinct “low δ¹⁵N” and “high δ¹⁵N” groups. δ¹⁵N analysis of amino acids confirmed that this disparity resulted from isotopic differences at the base of the food chain and not from differences in trophic position between the two groups. Satellite tracking of 13 individuals indicated that their bulk skin δ¹⁵N value was linked to the particular foraging region of each turtle. These findings confirm that prevailing marine isoscapes of foraging areas can be reflected in the isotopic compositions of marine turtle body tissues sampled at nesting beaches. We use a Bayesian mixture model to show that between 82 and 100% of the 78 skin-sampled turtles could be assigned with confidence to either the eastern Pacific or western Pacific, with 33 to 66% of all turtles foraging in the eastern Pacific. Our forensic approach validates the use of stable isotopes to depict leatherback turtle movements over broad spatial ranges and is timely for establishing wise conservation efforts in light of this species’ imminent risk of extinction in the Pacific.

From June 1995 to August 2002 we assessed green turtle (Chelonia mydas) population structure and survival, and identified human impacts at Bahía de los Angeles, a large bay that was once the site of the greatest sea turtle harvest rates in the Gulf of California, Mexico. Turtles were captured live with entanglement nets and mortality was quantified through stranding surveys and flipper tag recoveries. A total of 14,820 netting hours (617·5 d) resulted in 255 captures of 200 green turtles. Straight-carapace length and mass ranged from 46·0–100·0 cm (mean=74·3±0·7 cm) and 14·5–145·0 kg (mean=61·5±1·7 kg), respectively. The size–frequency distribution remained stable during all years and among all capture locations. Anthropogenic-derived injuries ranging from missing flippers to boat propeller scars were present in 4% of captured turtles. Remains of 18 turtles were found at dumpsites, nine stranded turtles were encountered in the study area, and flipper tags from seven turtles were recovered. Survival was estimated at 0·58 for juveniles and 0·97 for adults using a joint live-recapture and dead-recovery model (Burnham model). Low survival among juveniles, declining annual catch per unit effort, and the presence of butchered carcasses indicated human activities continue to impact green turtles at this foraging area.

The ecologies of vertebrate species have been increasingly studied via stable isotope analyses of small quantities of body tissues. However, critical assumptions relating to the consistency in stable isotopic values in consumer tissues and their diet as well as the rate of incorporation of diet-derived stable isotopes into consumer tissues remain poorly validated for most taxa despite numerous stable isotope studies targeting natural systems. In this study, we measured stable carbon and nitrogen diet–tissue discrimination and elemental turnover in whole blood, red blood cells, blood plasma, brain, liver, pectoralis major muscle, pubioshiofemoralis internus muscle, stratum corneum (sc) dermis, and stratum germinativum (sg) dermis of Pond Sliders (Trachemys scripta) fed ad libitum on two isotopically distinct diets. Turtles were fed a soy-based control diet (32% protein, 3% lipids, 4% fiber), and after 146 d, a subset was switched to a fish meal-based experimental diet (44% protein, 24% lipids, 3% ...