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Sea turtles represent an ancient lineage of marine vertebrates that evolved from terrestrial ancestors over 100 Mya. The genomic basis of the unique physiological and ecological traits enabling these species to thrive in diverse marine habitats remains largely unknown. Additionally, many populations have drastically declined due to anthropogenic activities over the past two centuries, and their recovery is a high global conservation priority. We generated and analyzed high-quality reference genomes for the leatherback (Dermochelys coriacea) and green (Chelonia mydas) turtles, representing the two extant sea turtle families. These genomes are highly syntenic and homologous, but localized regions of noncollinearity were associated with higher copy numbers of immune, zinc-finger, and olfactory receptor (OR) genes in green turtles, with ORs related to waterborne odorants greatly expanded in green turtles. Our findings suggest that divergent evolution of these key gene families may underlie immunological and sensory adaptations assisting navigation, occupancy of neritic versus pelagic environments, and diet specialization. Reduced collinearity was especially prevalent in microchromosomes, with greater gene content, heterozygosity, and genetic distances between species, supporting their critical role in vertebrate evolutionary adaptation. Finally, diversity and demographic histories starkly contrasted between species, indicating that leatherback turtles have had a low yet stable effective population size, exhibit extremely low diversity compared with other reptiles, and harbor a higher genetic load compared with green turtles, reinforcing concern over their persistence under future climate scenarios. These genomes provide invaluable resources for advancing our understanding of evolution and conservation best practices in an imperiled vertebrate lineage. This work was completed in part with resources provided by the University of Massachusetts' Green High Performance Computing Cluster (GHPCC). Funding was provided by the University of Massachusetts Amherst, NSF-IOS (grant #1904439 to L.M.K.), NOAA-Fisheries, National Research Council postdoctoral fellowship program to L.M.K., VGP, Rockefeller University, to E.D.J., HHMI to E.D.J., the Sanger Institute, Max-Planck-Gesellschaft, and grant contributions from Tom Gilbert, Paul Flicek, R.W.M., Karen A. Bjorndal, Alan B. Bolten, Ed Braun, N.J.G., T.M.-B., and A.F.S. We acknowledge CONICYT-DAAD for scholarship support to T.C.-V., the São Paulo Research Foundation to E.K.S.R.–FAPESP (grant #2020/10372-6). BeGenDiv is partially funded by the German Federal Ministry of Education and Research (BMbF, Förderkennzeichen 033W034A). The work of F.T.-N. and P.M. was supported by the Intramural Research Program of the National Library of Medicine, NIH. The work of M.P. was partially funded through the Federal Ministry of Education and Research (grant 01IS18026C). H.P. was supported by a Formació de Personal Investigador fellowship from Generalitat de Catalunya (FI_B100131). M.K. was supported by “la Caixa” Foundation (ID 100010434; code LCF/BQ/PR19/11700002), the Vienna Science and Technology Fund (WWTF), and the City of Vienna (VRG20-001). Funding for green turtle resequencing was provided by a Welsh Government Sêr Cymru II and the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 663830-BU115 and the Sea Turtle Conservancy, Florida Sea Turtle Grants Program (17-033R).

Hawksbill sea turtles (Eretmochelys imbricata) from the Hawaiian archipelago form a small, genetically isolated, population consisting of only a few tens of individuals breeding annually. Most females nest on the island of Hawai’i, but little is known about the demographics of this rookery. This study used genetic relatedness, inferred from 135 microhaplotype markers, to determine breeding sex-ratios, estimate female nesting frequency, and assess relationships between individuals nesting on different beaches. Samples were collected during the 2017 nesting season and final data included 13 nesting females and 1,002 unhatched embryos, salvaged from 41 nests, 13 of which had no observed mother. Results show that most females used a single nesting beach laying 1-5 nests each. From female and offspring alleles the paternal genotypes of 12 breeding males were reconstructed and many showed high relatedness to their mates. Pairwise relatedness of offspring revealed one instance of polygyny but otherwise suggest a 1:1 breeding-sex ratio. Relatedness analysis and spatial-autocorrelation of genotypes indicate non-random mating among complexes of nesting beaches, for both sexes, suggesting strong natal philopatry. Nesting complexes also showed unique patterns of inbreeding and outbreeding across loci, further indicating that Hawaiian hawksbill turtles have demographically discontinuous nesting populations at a fine spatial scale.

Kemp’s ridley sea turtles Lepidochelys kempii were disproportionately affected by the Deepwater Horizon (DWH) oil spill, which began on 20 April 2010. Embryo deformities were documented in inviable L. kempii eggs before (2008-2010) and after (2011-2013) the DWH spill in 2 Texas (USA) nesting areas (Upper Texas Coast and Padre Island National Seashore). Additional nesting trends, including clutch size and hatching success, were also investigated. Total and late-stage embryo deformity prevalence were 1.5 times greater after 2010 than before, but low in all nesting seasons (mean ± SD: 0.7 ± 8.5% total; 0.6 ± 8.0% late-stage) and did not differ between locations. Craniofacial and carapace deformities were the most frequently observed deformity types. Documented nests in both areas declined in 2010 relative to previous years, ending an exponential increase observed beginning in 1995. Clutch size remained consistent before and after the spill. Hatching success averaged 87.0 ± 33.3% in all years, but no effects from DWH were determined. Collectively, these data represent useful benchmarks against which to judge impacts of future crude oil spills and other catastrophic events.

Although the hawksbill turtle (Eretmochelys imbricata) nesting colony in Hawaiʻi may constitute one of the smallest hawksbill nesting populations in the world, it is also the largest in the U.S. Pacific Islands and the Central North Pacific Ocean. The isolated nature of the Hawaiian Archipelago has raised interest in the genetic characterization of the population, yet research remains lacking. In this study we use mitochondrial DNA (mtDNA) to provide the first genetic characterization of nesting (n = 108) and foraging (n = 29) hawksbills in the Hawaiian Islands. We combine our data with sequences previously published from the West and East Pacific to evaluate the genetic distinctiveness of the nesting assemblage in Hawaiʻi, and to gain insights into the origin of hawksbills found at foraging grounds around the archipelago. We found strong differentiation (FST > 0.238, P-value

Assessing population connectivity and identifying conservation units are critical to formulating effective management plans for marine turtles. We combined a multiplexed targeted enrichment capture technique and high-throughput sequencing to discover single nucleotide polymorphisms (SNPs) and to genotype hawksbill turtles (Eretmochelys imbricata) to examine population structure. Our approach discovered 455 potential informative SNPs for hawksbill turtles. We optimized 25 of the 455 SNPs discovered and used them to identify preliminary evidence of hawksbill population structure, suggesting that these markers will be informative in discerning conservation units when applied to larger sample sizes in future studies.

Advances in high-throughput sequencing (HTS) technologies coupled with increased interdisciplinary collaboration are rapidly expanding capacity in the scope and scale of wildlife genetic studies. While existing HTS methods can be directly applied to address some evolutionary and ecological questions, certain research goals necessitate tailoring methods to specific study organisms, such as high-throughput genotyping of the same loci that are comparable over large spatial and temporal scales. These needs are particularly common for studies of highly mobile species of conservation concern like marine turtles, where life history traits, limited financial resources and other constraints require affordable, adaptable methods for HTS genotyping to meet a variety of study goals. Here, we present a versatile marine turtle HTS targeted enrichment platform adapted from the recently developed Rapture (RAD-Capture) method specifically designed to meet these research needs. Our results demonstrate consistent enrichment of targeted regions throughout the genome and discovery of candidate variants in all species examined for use in various conservation genetics applications. Accurate species identification confirmed the ability of our platform to genotype over 1,000 multiplexed samples and identified areas for future methodological improvement such as optimization for low initial concentration samples. Finally, analyses within green turtles supported the ability of this platform to identify informative SNPs for stock structure, population assignment and other applications over a broad geographic range of interest to management. This platform provides an additional tool for marine turtle genetic studies and broadens capacity for future large-scale initiatives such as collaborative global marine turtle genetic databases.

In this study we assessed the breeding population, or Management Unit (MU), origin of green turtles (Chelonia mydas) present at Yadua Island and Makogai Island foraging grounds in Fiji, central South Pacific. Based on analysis of mitochondrial (mt) DNA sequences from 150 immature green turtles caught during surveys carried out in 2015–2016, we identified a total of 18 haplotypes, the most common being CmP22.1 (44%) which is a primary haplotype characterizing the American Samoa breeding population. Results of a Bayesian mixed-stock analysis reveals that the two foraging grounds are used by green turtles from the American Samoa MU (72%, Credible Interval (CI): 56–87%), New Caledonia MU (17%, CI: 6–26%) and French Polynesia MU (7%, CI: 0–23%). The prominence of the contribution we found from the American Samoa MU compared to that of French Polynesia, both which have historic telemetry and tagging data showing connectivity with Fijian foraging areas, may reflect the current relative abundance of these two nesting populations and draws attention to a need to update population surveys and identify any significant nesting in Fiji that may have been overlooked.

Trophic position and niche width are fundamental components of a species’ ecology, reflecting resource use, and influencing key demographic parameters such as somatic growth, maturation, and survival. Concepts about a species’ trophic niche space have important implications for local management and habitat protection, and can shed light about resilience to changing climate for species occurring over broad spatial scales. For elusive marine animals such as sea turtles, trophic niche is challenging to study, and researchers often rely on other metrics, such as isotopic niche, as a proxy. Here, stable isotope analysis (δ13C and δ15N values) was conducted on bulk skin tissue of 718 green turtles (Chelonia mydas) distributed among 16 foraging areas in the eastern Pacific from the USA to Chile, a range spanning ~10,000 km. Compound‐specific nitrogen isotope analysis of amino acids (CSIA‐AA) was applied to 21 turtles among seven sites. Isotopic niche space was determined via Bayesian ellipse area (BEA) and convex hull area (CHA) analyses of bulk isotope values, which were also used along with amino acid δ15N values to determine trophic position (TP). Substantial variability in bulk tissue δ13C and δ15N values was found within and among sites, and amino acid δ15N values confirmed this was largely due to spatial differences in baseline nitrogen isotopic compositions, but also to a lesser extent from TP differences among the green turtle foraging populations. Isotope niche space varied among sites, influenced by the diversity of prey types and relative input of terrestrial‐ vs. marine‐derived nutrients; BEAs were the most suitable measurement of isotopic niche space due to the larger influence of outlying values with the CHA approach. Amino acid isotope‐derived TP estimates that accounted for local habitat conditions (e.g., mixed seagrass/macroalgae diet) performed the best among several approaches; TP ranged from 2.3 to 3.6, which indicates an omnivorous diet for most populations. In addition to providing additional spatial resolution for δ13C and δ15N isoscapes in the eastern Pacific, especially in coastal habitats, this study further establishes CSIA‐AA as an effective tool to study the trophic ecology of sea turtles across a variety of food webs and habitats.

BackgroundTranscriptomic data has demonstrated utility to advance the study of physiological diversity and organisms’ responses to environmental stressors. However, a lack of genomic resources and challenges associated with collecting high-quality RNA can limit its application for many wild populations. Minimally invasive blood sampling combined with de novo transcriptomic approaches has great potential to alleviate these barriers. Here, we advance these goals for marine turtles by generating high quality de novo blood transcriptome assemblies to characterize functional diversity and compare global transcriptional profiles between tissues, species, and foraging aggregations.ResultsWe generated high quality blood transcriptome assemblies for hawksbill (Eretmochelys imbricata),loggerhead (Caretta caretta), green (Chelonia mydas), and leatherback (Dermochelys coriacea) turtles. The functional diversity in assembled blood transcriptomes was comparable to those from more traditionally sampled tissues. A total of 31.3% of orthogroups identified were present in all four species, representing a core set of conserved genes expressed in blood and shared across marine turtle species. We observed strong species-specific expression of these genes, as well as distinct transcriptomic profiles between green turtle foraging aggregations that inhabit areas of greater or lesser anthropogenic disturbance.ConclusionsObtaining global gene expression data through non-lethal, minimally invasive sampling can greatly expand the applications of RNA-sequencing in protected long-lived species such as marine turtles. The distinct differences in gene expression signatures between species and foraging aggregations provide insight into the functional genomics underlying the diversity in this ancient vertebrate lineage. The transcriptomic resources generated here can be used in further studies examining the evolutionary ecology and anthropogenic impacts on marine turtles.

Marine mesotherms are able to occupy broader thermal niches than ectotherms; however, this means they must thermoregulate according to diverse thermal conditions across the ocean. Knowledge remains limited about how differences in thermal conditions within the selected habitats affect the behavior and associated ecological traits in mesotherms. Here, we tested if a marine mesotherm, leatherback turtles (Dermochelys coriacea) generally maintain their body temperature by diving to greater depths to expose themselves to cold waters as sea surface temperature becomes warmer. Moreover, we investigate how such behavioral thermoregulation may influence their ecological traits (e.g., foraging and migration). We analyzed 49,461 dive profiles and 16,255 temperature‐depth profiles from 17 leatherback turtles migrating across the North Pacific using satellite‐linked data loggers. Our results showed that leatherbacks changed their dive behavior regionally, in response to sea surface temperature and potential foraging habitats. Dive type classification revealed that V‐shaped, presumably gliding dives, became deeper when the surface water was warmer, likely because leatherbacks dive to deep cold waters to avoid overheating. We found five hotspots of wiggle (up‐and‐down undulations in the depth profile) dives that are indicative of foraging behavior, ranging from tropical to cool‐temperate regions in the North Pacific. The dive patterns in potential foraging hotspots indicate that leatherbacks engage in behavioral thermoregulation in warmer regions. Such bioenergetics may affect the time available for foraging activity during migration phases. In cool‐temperate foraging areas, leatherbacks are indeed able to spend more time foraging due to mesothermy. However, the trade‐off between energy gain by foraging activity and additional migration cost of moving to higher latitude areas might not result in greater reproductive output for leatherbacks foraging in distant cool‐temperate regions. These patterns highlight that mesothermy represents a trade‐off: Leatherbacks can utilize cooler waters but must engage in additional behavioral thermoregulation (i.e., extremely deep dives) in warmer waters. Thus, mesothermy might not provide a direct fitness advantage to all individual leatherback turtles; rather, it affords a species‐level fitness advantage by allowing a greater diversity of habitats to be utilized.

WOS:000656210100001; International audience; Credit systems for mitigation of bycatch and habitat impact, incentive-based approaches, incentivize changes in fishery operator behavior and decision-making and allow flexibility in a least-cost method. Three types of credit systems, originally developed to address environmental pollution, are presented and evaluated as currently underutilized incentive-based approaches. The first, a cap-and-trade approach, evolved out of direct regulation through restricted limits with flexibility through the creation of tradeable unused portion of the limit, called credits. The second, a penalty-reward system, incentivizes bycatch- and habit-impact- reducing vessel behavior through rewards for positive behavior, and penalties for negative behavior. The third is a hybrid of the first two. All three systems can be used in the context of both absolute (fixed) and relative (rate-based or proportional) credits. Transferable habitat impact credit systems are developed for area management. The cap-and-trade credit system is directly compared to a comparable property rights system in terms of characteristics, strengths, weakness, and applicability. The Scottish Conservation Scheme and halibut bycatch reduction in the Alaskan multispecies groundfish fishery provide real-world examples of success with credit systems. The strengths, weaknesses, and applicability of credit systems are summarized, along with a set of recommendations. Cap-andtrade credit systems provide an important alternative to property rights, such as when rights are not feasible, and for this reason should prove useful for international fisheries. Penalty-reward and hybrid credit systems can substitute for cap-and-trade credit systems or property rights or complement them by addressing a related but otherwise unaddressed issue.

Fisheries bycatch conservation and management can be analyzed and implemented through the biodiversity mitigation hierarchy using one of four basic approaches: (1) private solutions, including voluntary, moral suasion, and intrinsic motivation; (2) direct or ?command-and-control? regulation starting from the fishery management authority down to the vessel; (3) incentive-or market-based to alter producer and consumer behavior and decision-making; and (4) hybrid of direct and incentive-based regulation through liability laws. Lessons can be learned from terrestrial and energy conservation, water management, forestry, and atmospheric pollution measures, such as the use of offsets, tradeable rights to externalities, and liability considerations. General bycatch conservation and management principles emerge based on a multidisciplinary approach and a wide array of private and public measures for incentivizing bycatch mitigation. ABSTRACT Bycatch refers most often to those species incidentally taken in fishing operations aimed at other (target) species. Bycatch in this paper refers to species accidentally caught other than the target species, brought on board, dead or alive, and that can therefore be either released alive, discarded dead, or landed. Bycatch can be other finfish (including undersized target species), protected species (fishes, sea turtles, marine mammals, and seabirds), live corals, or sponge reefs. We include habitat impact (Holland and Schnier, 2006; Driscoll et al., 2017) with bycatch (hereafter simply bycatch). Central to this paper is the fact that bycatch species and living habitats include vulnerable, threatened, endangered, protected or otherwise emblematic species for which the take should be minimized. Bycatch in this paper is extended to include habitat impact. ABSTRACT Fisheries bycatch conservation and management can be analyzed and implemented through the biodiversity mitigation hierarchy using one of four basic approaches: (1) private solutions, including voluntary, moral suasion, and intrinsic motivation; (2) direct or ?command-and-control? regulation starting from the fishery management authority down to the vessel; (3) incentive- or market-based to alter producer and consumer behavior and decision-making; and (4) hybrid of direct and incentive-based regulation through liability laws. Lessons can be learned from terrestrial and energy conservation, water management, forestry, and atmospheric pollution measures, such as the use of offsets, tradeable rights to externalities, and liability considerations. General bycatch conservation and management principles emerge based on a multidisciplinary approach and a wide array of private and public measures for incentivizing bycatch mitigation.

Bycatch in fisheries is one of the greatest threats to marine megafauna such as sea turtles, and the Biodiversity Impact Mitigation Hierarchy (BIMH) has been proposed as an improved and holistic approach for integrating fisheries management with sea turtle conservation. The first three BIMH steps – avoid, minimize, and remediate – take place at sea where fishing activity is taking place. However, these at-sea measures are costly and difficult to effectively implement across the vast range of a highly migratory species. As such, some level of mortality continues, even when the first three steps of the BIMH are implemented as extensively as possible. These remaining negative impacts need to be addressed by compensatory conservation actions elsewhere, e.g., at sea turtle nesting beaches. As a case study, we use the critically endangered leatherback sea turtle nesting population in Papua Barat, Indonesia, to illustrate the opportunity for conservatory offsets to fisheries bycatch across the Pacific. We describe the community empowerment and nest protection programs that have been enhanced by the voluntary offsets from the tuna industry. While improved nest protection measures have helped optimize hatchling production, the engagement of the local communities, through activities that empower and enhance quality of life, has been a critical component to the successful increase in hatchlings. This momentum needs to be sustained and scaled-up to protect the majority of threatened nests over a consistent number of years to successfully provide the recruitment boost needed at the population level. These compensatory off-site conservation measures are also the most cost-effective means of achieving increases in leatherback populations, and perhaps one of the most critical components of the recovery strategy for Pacific leatherbacks.

Knowledge of demographic processes and life history strategies is necessary for the conservation and management of endangered sea turtle populations, but it is difficult to ascertain because of the limited accessibility to marine environments that sea turtles use during the different stages of their life cycle. In such cases, molecular genetics and genomic approaches are useful to assess mating systems and operational sex ratios (OSR), which ultimately influence demography. This pilot study used genome-wide single nucleotide polymorphism (SNP) genetic markers for exploring kinship and mating systems in sea turtles where major obstacles prevent a comprehensive assessment in the wild. We sampled 217 young hawksbill turtles (Eretmochelys imbricata) of unknown parentage that had originally been collected locally from seven nests and were being temporarily kept in captivity by Treasure Island Ltd as part of its captive rearing conservation project at Bounty and Treasure Islands, Fiji, in the South Pacific. The raw dataset comprised 13,573 SNPs, of which we retained 639 SNPs for parentage and relatedness analyses. Our findings from seven different pairs of parents suggest a 1:1 male:female OSR and demonstrate that genome-wide SNP genotyping approaches can be used to infer OSR. Knowledge of OSR can help evaluate the magnitude of the impact of warming temperatures and consequent feminisation in sea turtles. Our approach can complement or substitute field observation of breeding males and nesting females when logistical or budgetary constraints prevent observation of OSR in wild sea turtle populations. This approach allows inference of OSR. Protection of beaches with a higher number of pairs of parents should be prioritised to increase genetic resilience. Conservation actions in rookeries with a female-skewed OSR should be prioritised to address population declines in the long run., The research was supported by The University of the South Pacific (USP SRT grant F1006-RI001-71502-623 to S.P. and C.R. and USP FRC grant F3086-FST15-71502-001 to S.S.P.).

Assessments of fisheries by‐catch on marine megafauna are important for developing effective management strategies. For sea turtles, impacts may be evident in nesting population trends, but generally only after a lag, as turtles are slow to mature. We examined 850 loggerhead turtle (Caretta caretta) by‐catch samples collected over 14 years throughout the western North Atlantic to identify source nesting populations. We identified proportions of turtles from 19 distinct management units (MUs), using mitochondrial DNA and mixed stock analysis, considering population size. We found a significant split in the distribution of small versus large loggerheads to the north and south of Cape Hatteras, North Carolina (latitude 35°N). North of Cape Hatteras, large turtles came from south‐east Florida (SEFL; 44% ± 15%) and the northern United States (33% ± 16%) MUs, while south of Cape Hatteras, the major contributors were Central East Florida (52% ± 20%) and south‐east Florida (SEFL; 41% ± 20%). Small turtles in the north came from Central East Florida (64% ± 14%), and in the south, south‐east Florida had the highest representation (56% ± 25%). There was little contribution from Mediterranean and Cape Verde populations, indicating low risk from western North Atlantic by‐catch to MUs in the Mediterranean. Understanding where threats may impact source populations is important, particularly for larger size turtles, as these individuals have the highest reproductive value. These findings allow more informed threat assessments to be conducted for loggerhead turtles considering spatial and demographic structure.

Genetic analyses of nuclear DNA (e.g., microsatellites) are a primary tool for investigating mating systems in reptiles, particularly marine turtles. Whereas studies over the past two decades have demonstrated that polyandry (i.e., females mating with multiple males) is common in marine turtles, polygyny (i.e., males mating with multiple females) has rarely been reported. In this study we investigated the mating structure of Critically Endangered hawksbill turtles (Eretmochelys imbricata) at Bahia de Jiquilisco in El Salvador, one of the largest rookeries in the eastern Pacific Ocean. We collected genetic samples from 34 nesting females and hatchlings from 41 clutches during the 2015 nesting season, including one nest from each of 27 females and two nests from seven additional females. Using six highly polymorphic microsatellite loci, we reconstructed the paternal genotypes for 22 known male turtles and discovered that seven (31.8%) sired nests from multiple females, which represents the highest polygyny level reported to date for marine turtles and suggests that this is a common mating structure for this population. We also detected multiple paternity in four (11.8%) clutches from the 34 females analyzed, confirming polyandrous mating strategies are also employed. The high level of polygyny we documented suggests there may be a limited number of sexually mature males at Bahia de Jiquilisco; a scenario supported by multiple lines of empirical evidence. Our findings highlight key management uncertainties, including whether polygynous mating strategies can compensate for potential ongoing feminization and the low number of adult males found for this and possibly other marine turtle populations.

Multiple paternity is a common phenomenon among marine turtles. This behavior is associated with male density and sperm storage in marine species, but no fitness benefits have been detected in offspring from multiple-sired nests. The green turtle (Chelonia mydas) has been commonly studied around the world. Evidence of multiple paternity in C. mydas ranges from almost zero to 100%. In this study, we investigate multiple paternity in C. mydas using microsatellites to determine the number of males that fertilized clutches during two nesting seasons at a high-density nesting beach in the west coast in Michoacan state, Mexico. The minimum number of eggs per nest needed to detect multiple paternity and the number of males involved in fertilization were also assessed. The results indicated that multiple paternity occurred in up to 75% of the nest samples. In addition, the minimum number of eggs per nest required to detect multiple genotype contributions was 6.66 for two fathers, 12.44 for three fathers, 15.49 for four fathers and 20.24 for five fathers. Females fertilized their eggs using contributions from different males between and within clutches during the nesting season. This behavior led to a multiple paternity pattern, which can be advantageous during different life stages but not necessarily during early life.

The green turtle ( Chelonia mydas ) foraging aggregation along the Texas coast has increased dramatically in recent years, but the source populations for these turtles have not been adequately resolved. Previous mixed stock analysis (MSA) based on 490 base pair (bp) mitochondrial control region haplotypes suggested a large Florida contribution, but widespread sharing of common haplotypes among potential source populations and incomplete source population baseline data precluded precise assessment. To test the hypothesis that Texas turtles may represent proximal western Gulf of Mexico (GoM) nesting populations, we analyzed novel rookery samples from Rancho Nuevo, Tamaulipas, Mexico (RNMX) and conducted oceanic connectivity simulations. The RNMX samples yielded haplotypes CM-A1.1 and CM-A3.1 in frequencies not significantly different from those of the central eastern Florida nesting population. However, mitogenomic sequencing identified a diagnostic mitochondrial SNP (mtSNP) variant that is fixed in RNMX relative to the Florida CM-A1.1 lineage. Pairwise comparisons indicate that the Tamaulipas rookery represents a discrete population relative to those previously described in the northern Greater Caribbean, warranting recognition of a western GoM management unit (MU). Contrary to previous findings, the Florida populations were ruled out as major contributors to the Texas aggregation through screening of the mtSNP. Mixed stock analysis incorporating the mtSNP data suggested a western GoM origin for approximately 70% of the Texas foraging aggregation, with Quintana Roo contributing the majority of the remainder. Backtracking simulations within an ocean circulation model were broadly congruent with genetic results in indicating substantial probability of oceanic transport from Mexican rookeries to the Texas coast (68%) while also dismissing the possibility of transport from the eastern Florida rookeries (0%). The mixed stock analyses and backtracking simulations are consistent with previous hypotheses implicating oceanic dispersal followed by natal homing by neritic juveniles to explain juvenile green turtle distributions. In contrast to a pattern of stepping stone connectivity across the remaining northern Greater Caribbean, the Texas foraging aggregation was distinct from all others analyzed in the region, including one in the eastern GoM. This isolation highlights the significance of Texas as developmental habitat for the proposed western GoM MU and reiterates the importance of continued international cooperation to facilitate recovery of this stock. This study also underscores the importance of satisfying underlying assumptions of mixed stock analysis in order to make robust inferences of connectivity.

Aim: To examine the genetic structure and global phylogeography of the endangered green sea turtle, Chelonia mydas, in light of past climatic events and current conservation needs. Location: Tropical and subtropical beaches around the world. Methods: We analysed 386 base pairs of the mitochondrial (mt)DNA control region of 4,878 individual nesting green turtle samples from 127 rookeries globally. We used phylogeographic analysis to assess how demographic history, dispersal and barriers to gene flow have led to the current distribution of mtDNA lineages. Results: We identified 11 divergent lineages that were tied to specific biogeographical regions. The phylogenetic analyses revealed an ancient origin for the species centred in the Indo-Pacific and more recent colonization of the Central/Eastern Pacific as well as the Atlantic Basin. Overall the phylogeographic structure was strong but with a clear pattern of regional connectivity among rookeries. A Large genetic separation was found where there were obvious barriers to dispersal such as between the Atlantic and Pacific oceans and across the Pacific Ocean, as well as less obvious barriers to dispersal. Admixture of mtDNA haplotype lineages was detected at latitudinal extremes across the Indian Ocean and western Pacific Ocean resulting in these areas being nucleotide diversity hotspots. The highest regional genetic diversity and high endemic richness was observed in the SW Pacific, NW Pacific, SW Indian and NW Indian oceans. Main conclusions: Past climatic fluctuations greatly affected the distribution of genetic diversity in the highly migratory green turtle. Our data suggest that past climatic events influenced local populations in different ways and the species appears to have survived the last glaciations in multiple glacial refugia.

There have been efforts around the globe to track individuals of many marine species and assess their movements and distribution, with the putative goal of supporting their conservation and management. Determining whether, and how, tracking data have been successfully applied to address real-world conservation issues is, however, difficult. Here, we compile a broad range of case studies from diverse marine taxa to show how tracking data have helped inform conservation policy and management, including reductions in fisheries bycatch and vessel strikes, and the design and administration of marine protected areas and important habitats. Using these examples, we highlight pathways through which the past and future investment in collecting animal tracking data might be better used to achieve tangible conservation benefits.

Effective conservation of globally distributed marine species relies on identification of demographically independent populations to ensure that management actions are directed at the appropriate scale. This identification is particularly challenging for species with complex life histories when local breeding populations have not been adequately sampled. We used mtDNA to analyze the population structure of loggerhead turtles from a total of 555 samples collected from 12 nesting sites in Japan in the Northwest Pacific, including previously unsampled rookeries in the Ryukyu Archipelago, for a comprehensive coverage of the nesting distribution. We identified a total of 9 haplotypes based on 820 bp of the mtDNA control region, including 5 variants of a single previously described 380 bp haplotype. We discovered that 1 haplotype (CcP1.1) previously rare in the North Pacific is common in the Ryukyu Archipelago. Based on analysis of haplotype frequencies, we found significant differentiation among regionally grouped nesting populations (analysis of molecular variance p < 0.0001, df = 8; pairwise FST ranging from 0.033 to 0.145). Our results provide evidence to support the recognition of 3 management units (MU) within the NW Pacific Regional Management Unit (RMU). These include (1) the Ryukyu MU that includes Okinawa, Okinoerabu and Amami, (2) Yakushima Island MU and (3) a Mainland MU that includes Bousou, Enshu-nada, Shikoku, Kii and Eastern Kyushu. These new data from Japan will provide important baseline data for global genetic stock assessments and contribute to our understanding of the population structure, ecology and life history of this migratory marine species in the northern Pacific.