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Determining sex ratios of endangered populations is important for wildlife management, particularly species subject to sex-specific threats or that exhibit temperature-dependent sex determination. Sea turtle sex is determined by incubation temperature and individuals lack external sex-based traits until sexual maturity. Previous research utilized serum/plasma testosterone radioimmunoassays (RIA) to determine sex in immature/juvenile sea turtles. However, there has been a growing application of enzyme-linked immunosorbent assay (ELISA) for wildlife endocrinology studies, but no study on sea turtles has compared the results of ELISA and RIA. This study provides the first sex ratio for a threatened East Pacific green sea turtle (Chelonia mydas) foraging aggregation, a critical step for future management of this species. Here, we validate a testosterone ELISA and compare results between RIA and ELISA of duplicate samples. The ELISA demonstrated excellent correspondence with the RIA for providing testosterone concentrations for sex determination. Neither assay proved reliable for predicting the sex of reproductively active females with increased testosterone production. We then applied ELISA to examine the sex ratio of 69 green turtles foraging in San Diego Bay, California. Of 45 immature turtles sampled, sex could not be determined for three turtles because testosterone concentrations fell between the ranges for either sex (females: 4.1–113.1 pg/mL, males: 198.4–2,613.0 pg/mL) and these turtles were not subsequently recaptured to enable sex determination; using a Bayesian model to predict probabilities of turtle sex we predicted all three ‘unknowns’ were female (> 0.86). Additionally, the model assigned all turtles with their correct sex (if determined at recapture) with 100% accuracy. Results indicated a female bias (2.83F:1M) among all turtles in the aggregation; when focusing only on putative immature turtles the sex ratio was 3.5F:1M. With appropriate validation, ELISA sexing could be applied to other sea turtle species, and serve as a crucial conservation tool. [ABSTRACT FROM AUTHOR]

The article offers information on possible causes of mortality for adult leatherback turtles (Dermochelys coriacea). It states that a switching state-space model was applied to distinguish migratory and area-restricted search behaviors. It indicated a high spatial segregation between East Pacific(EP) and West Pacific(WP) nesting populations.They have high risk of exposure to many different fisheries and more susceptible to any temperature or prey changes that occur in response to climate change.

Mitochondrial DNA analyses have been useful for resolving maternal lineages and migratory behavior to foraging grounds (FG) in sea turtles. However, little is known about source rookeries and haplotype composition of foraging green turtle aggregations in the southeastern Pacific. We used mitochondrial DNA control region sequences to identify the haplotype composition of 55 green turtles, Chelonia mydas, captured in foraging grounds of Gorgona National Park in the Colombian Pacific. Amplified fragments of the control region (457 bp) revealed the presence of seven haplotypes, with haplotype (h) and nucleotide (p) diversities of h = 0.300±0.080 and p = π.009±0.005 respectively. The most common haplotype was CMP4 observed in 83% of individuals, followed by CMP22 (5%). The genetic composition of the Gorgona foraging population primarily comprised haplotypes that have been found at eastern Pacific rookeries including Mexico and the Galapagos, as well as haplotypes of unknown stock origin that likely originated from more distant western Pacific rookeries. Mixed stock analysis suggests that the Gorgona FG population is comprised mostly of animals from the Galapagos rookery (80%). Lagrangian drifter data showed that movement of turtles along the eastern Pacific coast and eastward from distant western and central Pacific sites was possible through passive drift. Our results highlight the importance of this protected area for conservation management of green turtles recruited from distant sites along the eastern Pacific Ocean. [ABSTRACT FROM AUTHOR]

A group of researchers, managers, and tribal leaders with extensive local knowledge from Papua New Guinea, Solomon Islands, Vanuatu, and Papua, Indonesia, provided new information on the status of leatherback nesting populations in the western Pacific Ocean. Twenty-eight nesting sites were identified, of which 21 were previously unknown or poorly described. Although data are still incomplete, we estimate a total of ca. 5000-9200 nests currently laid each year among these 28 sites, with approximately 75% of this nesting activity concentrated at 4 sites along the northwest coast (Bird's Head Peninsula) of Papua, Indonesia. Genetic analysis by using mitochondrial deoxyribonucleic acid sequences identified a total of 6 haplutypes among the 106 samples analyzed for Solomon Islands, Papua, and Papua New Guinea, including a unique common haplotype that is only found in these western Pacific populations. There was no significant difference in haplotype frequencies among these rookeries, which suggests that they represent a metapopulation composed of a single genetic stock. Further work is needed to define the demographic structure within this metapopulation. [ABSTRACT FROM AUTHOR]

Abstract: We analyzed satellite track data for 186 loggerhead sea turtles in the North Pacific Ocean using remotely sensed environmental data to characterize pelagic habitat. A large number of candidate habitat variables were merged to the satellite track data and statistically compared to background values over a large spatiotemporal grid which bounded overall occupancy. Five statistically significant variables were identified out of the 16 environmental variables examined. Two of these variables have strong seasonal, interannual, and spatial patterns (sea surface temperature and chlorophyll a concentration), while three others were primarily spatial (earth magnetic force, earth magnetic declination, and earth magnetic inclination). Habitat selectivity for these variables was quantified using preference curve methodology established in the foraging literature. The output from the selectivity curves was used to predict a multivariate loggerhead sea turtle habitat index across the pelagic North Pacific. This predicted habitat was ground-truthed with newly available satellite track data. [Copyright &y& Elsevier]