Para ayudar a la conservación de las poblaciones de tortugas marinas, es importante conocer sus rutas migratorias y el uso del hábitat de alimentación cuando las hembras están lejos de los sitios de anidación. En este estudio, se rastrearon por satélite cinco tortugas carey (Eretmochelys imbricata) entre 2000 y 2004 tras la anidación en los Cayos Perla, ubicados frente a la costa caribeña central de Nicaragua. Las cinco hembras fueron rastreadas en dirección noreste hacia tres áreas de alimentación distintas en la plataforma continental de Nicaragua, con desplazamientos desde la colonia de entre 140.8 km y 411.2 km. Los análisis de distribuciones de uso (DUs) a nivel de 50% de dos hembras, calculadas mediante las ubicaciones de Argos, reflejaron áreas núcleo entre anidaciones de 6.8 km2 y 7.7 km2, mientras que las DUs de alimentación al 50% (n = 5) variaron entre 12.5 km2 y 62.7 km2. Nuestros resultados se suman a los de otros sugiriendo que la costa Caribe de Nicaragua, desde los Cayos Perla hacia el norte, e incluyendo la porción occidental de la Nicaragua Rise, es un epicentro de hábitats migratorios y de alimentación para las tortugas marinas. Interpretamos nuestros hallazgos en el contexto de otras investigaciones en la región para sugerir que el 18.9% (n = 40) de las tortugas carey rastreadas por satélite durante sus migraciones posteriores a la anidación en 13 naciones o territorios en el Caribe, el sur del Golfo de Méexico y el archipiélago de Lucaya se alimentaron en la parte occidental de la Nicaragua Rise. Debido a esta creciente evidencia, medidas de conservación dirigidas a reducir las amenazas prioritarias que afectan a las tortugas carey y sus hábitats en la parte occidental de la Nicaragua Rise tendrían, sin duda, impactos positivos en las poblaciones de tortugas carey en el Caribe. Con este fin, el establecimiento de un acuerdo bilateral entre Nicaragua y Honduras para manejar de forma conjunta el uso de los recursos marinos en esta región contribuiría a los esfuerzos de conservación enfocados en las tortugas carey. Una mayor colaboración con otras naciones del Caribe cuyas poblaciones de tortuga carey comparten estas aguas mejoraría el futuro de conservación de esta especie en peligro crítico de extinción.

Over recent decades, the eastern North Pacific Ocean (ENP) has undergone significant climate-driven change, characterized by rising sea surface temperatures (SSTs), a northward expansion of the North Pacific Transition Zone (NPTZ), and more frequent marine heatwaves. Juvenile North Pacific loggerhead sea turtles (Caretta caretta), a highly mobile species sensitive to environmental variability, have emerged as a sentinel species within the region. When North Pacific loggerheads migrate from the eastern subtropical gyre to coastal habitat, they do so offshore of the Baja California Peninsula, Mexico. Analysis of an extensive satellite tracking data set (n=285,1997–2023) revealed no prior observations of juveniles entering the colder, nutrient-rich waters of the northern California Current System (CCS). However, the gradual northward shift of loggerhead foraging habitat has been observed in parallel with an increasingly oligotrophic NPTZ. In 2024, four of 28 satellite-tracked individuals deviated from historic migratory routes and entered the northern CCS. To understand the physical mechanisms that enabled these novel movements, we integrated SST, chlorophyll-a concentrations, and surface current conditions experienced by these individuals and compared them to historical records within the region. During September-October 2024, these turtles reached 45°N latitude, where they encountered strong eastward flow within the North Pacific Current (NPC), thermally suitable conditions, and enhanced productivity. These conditions created a transient, high-latitude migratory corridor into the northern CCS. While three of these turtles benefited from reaching enhanced forage habitat in the California Current System, one likely suffered cold-stunning upon entry into suboptimal waters. The other 24 turtles remained south of the NPC, in the subtropical gyre. Our study represents the first confirmed use of a new, northern CCS migratory corridor by juvenile North Pacific loggerhead sea turtles. These findings expand on the conceptual framework of the ‘thermal corridor hypothesis,’ which suggests that sea turtles opportunistically exploit anomalously warm conditions to reach foraging habitats along the North American coast. They also emphasize the role of additional environmental drivers, such as advective current systems, in these movements. Under accelerated climate change, such transient pathways may become increasingly prevalent, with significant implications for conservation planning and fisheries management.

The North Pacific Transition Zone (NPTZ) is known as a global marine hotspot for many endangered and commercially significant highly mobile marine species. In the last few decades, the region has undergone unprecedented physical and biological transformations in response to climate variability and change. Although it is anticipated that many highly mobile species will need to adapt and shift their distributions, current predictions have relied on short-term data sets or modeled simulations. This has left a critical gap in our understanding of long-term (decadal or longer) change and species’ responses within the NPTZ. Here, we integrate nearly 3 decades of satellite tracking data from a climate sentinel, the juvenile North Pacific loggerhead sea turtle (Caretta caretta), with concurrent observations of sea surface temperature (SST) and chlorophyll-a concentrations to examine higher trophic level response to climate-induced changes within the eastern bounds of the NPTZ. Between 1997–2024, the NPTZ has warmed by 1.6°C and experienced an approximately 19% decline in mean surface chlorophyll-a concentration, a proxy for reduced productivity, resulting in a 28% (1.65 million km2) increase in total oligotrophic habitat in the eastern NPTZ. Over the same period, the average latitude of loggerhead sea turtle foraging habitat in the NPTZ has shifted northwards by 450–600 km. This represents a distributional shift rate of 116–200km/decade. In most years both the southern and northern range limits for the loggerhead turtle have shifted northward in tandem, indicating a habitat range shift rather than a range expansion. Our findings reveal significant physical and biological change to the NPTZ over the last quarter century and the first empirical evidence illustrating the substantial spatial response of a highly mobile megafaunal species. As the NPTZ continues to become more oligotrophic, these insights can provide vital information for dynamic conservation and management strategies within this critically important ecosystem.

PICES special research project “SEAturtle” launched in 2019 to understand the ecology of sea turtles around Jeju Island in relation to environmental stressors. Though COVID 19 had interrupted the project, we had quite a successful outcome over the last 5 years. Until now (June 15, 2023), a total of 16 iridium transmitters were deployed on sea turtles (14 on green sea turtles and 2 on loggerhead sea turtles). Among them, we received the signals successfully from 15 sea turtles. We found that quite a proportion of green sea turtles released in Jeju Island (N = 4 out of 12, approx. 40%) overwintered nearby even in the cold sea where the temperature dropped to 15 °C. The diving duration increased to approx. 6 hrs with decreasing temperature. Most of migrating green sea turtles (N = 4) traveled toward southern Japan which suggests a strong link to the population in Japan. Our population genetics result on green sea turtles stranded suggests that a subunit of Jeju population also have an affinity to Japan population. On the other hand, one of our loggerhead sea turtles moved westward but the other moved southward from Jeju Island, suggesting that they may also have connectivity to both Japan and China. Our populations genetics and stable isotope analysis on the commensal barnacles support this. We also have actively worked on the threat of plastics on Jeju populations and found that derelict recreational fishing gears might cause more serious problems than commercial derelict fishing gears. Microplastics are other threats to them too. To conserve the population of sea turtles in Jeju Island, we need further extensive research and should keep up international cooperation.

The importance of ocean currents in influencing the connectivity and dispersal of marine megafauna, including sea turtles, is becoming increasingly recognized. However, more comprehensive studies are needed on how these currents impact the genetic makeup and connectivity of green turtle Chelonia mydas (Linnaeus, 1758) populations in the Pacific Islands region. To address this gap, our study conducted genetic analyses of green turtles in foraging grounds from four Micronesian sites and predictive modelling of hatchling dispersal patterns based on ocean currents to explore connectivity between foraging grounds and rookeries across Micronesia. We analyzed mitochondrial DNA (mtDNA) haplotype frequencies from newly collected and published data. We used Bayesian mixed stock analysis (MSA) to estimate the relative proportion of turtles from different Management Units (MUs) within the foraging grounds. Our ocean current simulations predicted hatchling dispersal trajectories, revealing how passive drift may facilitate wide-ranging dispersal and connectivity among distant foraging and nesting sites. Across the four Micronesian foraging grounds, the MSA revealed varying contributions from different rookeries, with some turtles exhibiting rare, long-distance dispersal traits. Our study highlights the intricate relationship between oceanic currents and the spatial dynamics of green turtles across the Pacific. Our findings offer essential insights into the conservation and management of green turtles by highlighting the role of oceanic currents in shaping population connectivity. Future research should focus on expanding genetic analyses and refining ocean drift simulations to enhance our understanding of marine megafauna migration and inform regional conservation strategies effectively.

How juvenile sea turtles disperse during their first years at sea, known as the “lost years”, remains enigmatic. The oceanic circulation is known to play a major role, but the impact of the swimming activity is poorly understood, largely because juvenile tracking experiments rarely cover a significant fraction of the lost years’ period. In addition, errors in commonly used ocean current estimates make it difficult to properly separate, in tracking data, the effect of the swimming activity from that of the drift velocity. In this paper, we re-analyze the largest extant tracking data set concerning juvenile North Pacific (NP) loggerhead turtles (Caretta caretta), attempting to more precisely characterize their lost years’ swimming activity. Juvenile loggerhead trajectories are jointly analyzed with surface drifter trajectories from the Global Drifter Program and novel operational oceanography products from the Copernicus Marine service. Combining these data sets, we present a new method to reliably separate, at least on the large scale, the turtles swimming velocity from the drift velocity which includes the impact of the current, the wind and the waves. Results reveal that the smallest juveniles perform large seasonal north-south migrations while drifting eastwards with ocean currents. As they grow larger, many individuals are observed to change behavior. While keeping their meridional seasonal migrations, they initiate their homing journey swimming vigorously westwards towards their natal area (Japan), against prevailing currents. The juvenile NP loggerheads’ swimming activity is thus best described as a series of Drifting then Homing Seasonal Migrations. High interindividual synchronicity is observed during these migrations, especially around the fall equinox when individuals start swimming southwards. While open-ocean dispersal of juvenile sea turtles is known to be largely governed by ocean currents, our results demonstrate that juvenile loggerheads’ dispersal in the NP is also largely shaped by their well-organized large-scale swimming activity which involves ample seasonal migrations and vigorous homeward movements against adverse currents. Such an active swimming strategy comes with high energy expenditure probably balanced by increased foraging success. Analysis of forthcoming juvenile tracking experiments with our new data processing method should help reveal if juveniles from other sea turtle populations or species have evolved similar swimming strategies.

. - Four loggerhead turtles (Caretta caretta) with 81.0-85.3 cm curved carapace length were satellite tracked off Fujian and Guangdong provinces, southern China, in 2017 and 2022, and 2 movement patterns were revealed: resident and long-distanced seasonal migration. Identified hotspots include the eastern waters of Leizhou Peninsula, southern Taiwan Strait, central East China Sea, and the area between the southern Yellow Sea and the northern East China Sea. This study contributes foundational data for the North Pacific Regional Management Unit and highlights the need for cooperation among countries in East Asia.

The Hawaiian population of green turtles (Chelonia mydas) has increased since Federal and State protections were implemented in the mid 1970s, and reported stranding events have also increased. This study analyzed Hawai'i Island data: stranding location, date, size, sex, presence/absence of tumors, stranding status, and cause of stranding. A total of 754 stranded green turtles was reported from 1983-2022: 379 stranded on the east (windward) coast of Hawai'i Island and 375 on the west (leeward) coast. Strandings peaked in 2011 and 2018 and were highest from March to August. The most common known cause of stranding was hook-and-line fishing gear (21.4% of total strandings), followed by fibropapillomatosis (7.2%), human take (4.4%), miscellaneous (3.7%), boat impact (3.3%), shark attack (3.2%), and net (2.1%); however, 54.8% of strandings had no known cause. Statistical modeling did not provide convincing evidence of temporal changes in the distribution of strandings across three consolidated cause categories: human-caused; predation, disease, and weather; and unknown. Stranded turtles on east Hawai'i Island had a higher frequency of fibropapillomatosis, whereas west Hawai'i stranded turtles showed higher incidence of shark attacks. These results provide the first comprehensive analyses of stranding data from Hawai'i Island and provide information that can inform resource managers, policy makers, and the public about the various types and magnitudes of impacts, anthropogenic and natural, to green turtles so that mitigation measures can be put into practice. Our findings allow for comparison with other green turtle populations worldwide.

The northwestern Pacific region is an important habitat for sea turtles, hosting five species out of seven. There is still limited information available about the sea turtle aggregations around the Korean Peninsula, which is the northern boundary for many sea turtle species in the western Pacific area. The present study aims to investigate the migratory route of sea turtles visiting Jeju Island. Five species of sea turtles were identified from by-catch and stranding data between 2013 and 2022 on Jeju Island in Korea: green (Chelonia mydas; 24 individuals), loggerhead (Caretta caretta; 9), hawksbill (Eretmochelys imbricata; 2), olive ridley (Lepidochelys olivacea; 2), and leatherback (Dermochelys coriacea; 1). Mixed stock analysis using mitochondrial DNA haplotypes revealed that Jeju green turtles primarily originate from the rookeries of the Japanese Archipelago. This connectivity between two regions was also supported by the similar genetic composition of loggerhead turtles. Similarly, satellite tracking data showed that several green turtles originating from Jeju Island migrated to waters near the Ryukyu Archipelago in Japan. Nevertheless, about 60% of the tracked green turtles stayed near Jeju Island, with most overwintering there, indicating the long residency in Jeju Island. This study also provides the genetic sequences of other three species including new orphan haplotypes of hawksbill and olive ridley turtles. Our findings suggest that Jeju Island serves as a stable foraging habitat and provide insight into understanding the habitat range of sea turtles in the western Pacific.

Understanding consumer trophic status and long-term dietary changes can yield information about impacts of altered habitats on their ecology. In Hawai'i, coastal ecosystems have been significantly modified by the introduction of invasive seaweeds and mangroves, high nutrient load and overfishing, but so far, much is still to be understood about how these changes have affected the green turtle (Chelonia mydas). This study analyzed stable carbon, nitrogen, and sulfur isotope ratios in the bone tissue of modern and museum specimens of green turtles collected from 1901 to 2020 in Oahu and the North-western Hawaiian Islands to understand how their isotopic niche has changed through time, a crucial step towards restoring the ecological role of a formerly decimated species. The standard ellipse size and the total area of the convex hull of the isotopic niche of green turtles in three periods (1901-1951, 1992-2008, and 2018-2020) were calculated. The stable isotope values of ancient green turtles (1901-1951) suggest that they relied heavily on macroalgae even before the introduction of exotic species and eutrophication promoted the development of algal pastures. However, a few ancient green turtles relied heavily on seagrasses, and others complemented their macroalgae-based diets with significant amounts of animal matter. Such diet specialists were missing from the sample of current green sea turtles, suggesting that these foraging strategies are less common or perhaps even absent in the current population. The results suggest that green turtles have converged on the use of the most abundant resource, red macroalgae, likely because of the homogenization and simplification of coastal habitats and food webs due to anthropogenic influences. Restoring the population size of herbivorous fishes and a more diverse ecosystem structure may be necessary to recover the array of trophic strategies formerly present in the Hawaiian green turtle population.

This study builds upon the current understanding of green turtle population genetic structure in the Pacific that has largely been based on mitochondrial DNA (mtDNA), by examining nuclear DNA (nDNA) diversity, regional connectivity, and male-mediated gene flow. A total of 1,111 nesting green turtle samples were analyzed with 10 microsatellite markers from 20 Pacific rookeries. Population differentiation (F ST ) was significant (p <0.05) in all but 8 of 190 pairwise rookery comparisons. Pairwise F ST values and discriminant analysis of principal components (DAPC) revealed a defined East-West split consistent with mtDNA studies. Additionally, isolation-by-distance was evaluated with estimated effective migration surfaces (EEMS). The data indicated structure throughout the Pacific rookeries largely in agreement with stock structure defined by mtDNA studies, except for some areas on the Central American and Australian continental shelves, providing evidence of possible male-mediated gene flow. The series of analyses performed did indicate that male-mediated gene flow has likely occurred where breeding migration corridors of separate populations overlap with courtship areas. This may occur primarily along the margins of continents, including along Mexico and Central America in the East Pacific. Our study provides an ocean-wide baseline nDNA dataset for green turtle rookeries in the Pacific and reexamines the current thinking regarding the role of male turtles in the population dynamics of management units (MU) and to what extent nuclear gene flow occurs among designated MUs.

The present study determined if green sea turtles (Chelonia mydas) in Kailua Bay, Oahu, in the Hawaiian Islands have elevated blood and scute lead (Pb), arsenic (As), and antimony (Sb) concentrations resulting from lead deposition at a historic skeet shooting range. Blood and scute samples were collected and analyzed for Pb, As, and Sb via inductively coupled plasma-mass spectrometry. Prey, water, and sediment samples were also analyzed. Turtle samples in Kailua Bay (45) have blood Pb concentrations (328 +/- 195 ng/g) greater than a reference population (Howick Group of Islands, 29.2 +/- 17.1 ng/g). Compared with other green turtle populations, only turtles in Oman, Brazil, and San Diego, CA have blood Pb concentrations greater than turtles in Kailua Bay. The estimated daily exposure of Pb from algae sources in Kailua Bay (0.12 mg/kg/day) was significantly lower than the no observed adverse effect level (100 mg/kg) of red-eared slider turtles. However, the chronic effects of Pb on sea turtles is poorly understood and continued monitoring of this population will increase our understanding of the Pb and As loads of sea turtles in Kailua Bay. Environ Toxicol Chem 2023;00:1-15. (c) 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Longline fishing vessels, such as those that target tuna or billfish, also unintentionally catch endangered marine turtle species on the high seas. The stock composition of this bycatch is often unknown but potentially complex, with individuals coming from many possible origins on an ocean-basin scale. To better understand the stock composition of green turtle (Chelonia mydas) bycatch we obtained 46 turtles, 27-91 cm in curved carapace length, caught by Hawaii- and American Samoa-based pelagic longline fishing vessels across large areas of the North- and South-central Pacific. We genotyped these at nine microsatellite loci and one mitochondrial DNA marker, and used a baseline of 1,043 nesting female green turtles from beaches across the Pacific for population assignment and mixed-stock analysis. By analyzing both marker types jointly we were able to increase power and genetically resolve ten baseline stocks of nesting females with mean self-assignment and simulated accuracies of 75-97%. Above the Equator, green turtle bycatch was composed mostly of individuals from Hawaiian and Eastern Pacific stocks, with a small number from the Western Pacific. Below the Equator, the most common stocks in the bycatch were from Australia and the Coral Sea, American Samoa and French Polynesia, and the Galápagos Islands. Overall, turtles originating from East, West, and Central Pacific breeding populations were major components of the bycatch, suggesting that the geographic ranges of these populations overlap across large tracts of ocean during the pelagic life history stages.

This study conducted stable isotope analysis (δ 13 C, δ 15 N, and δ 34 S) on the epidermis and two skeletal elements (rib and squamosal bones) of Hawaiian green turtles ( Chelonia mydas ) and putative diet items obtained from two neritic sites: the Kona/Kohala coast and Oahu. Turtle tissues were collected in 2018–2020 and diet samples in 2018, 2019, and 2021. The effect of body size and sampling locality on individual bulk tissue isotope values was evaluated, and stable isotope mixing models based on δ 13 C, δ 15 N, and δ 34 S values from those tissues and four groups of food sources were used to reconstruct diet histories of the turtles. Mixing models indicated that green turtles along the Kona/Kohala coast consumed an omnivorous diet, whereas those from Oahu had an herbivorous diet. These diet make-ups are consistent with published gut content analyses. However, mixing models using the stable isotope ratios in rib and squamosal bone failed to yield reasonable diet histories, probably due to inadequacies of the applied trophic discrimination factor (TDF), a key model parameter. These results further establish that stable isotope ratios in the epidermis can be used effectively to study green turtle diet, but also reveal that more validation—and establishment of appropriate TDFs—is needed before bone can be used reliably to assess green turtle diet.

The Qilianyu cluster of the Xisha (Paracel) Islands has one of the few remaining green turtle Chelonia mydas rookeries in the China region. Genetic samples were obtained from dead green turtle embryos and hatchlings salvaged from post-hatched nests at Middle Island (n = 3), North Island (n = 9) and South Sand (n = 1) of the Qilianyu cluster in 2017-2019. The ~800 bp mitochondrial DNA control region was sequenced from the samples, and 5 haplotypes were identified belonging to 2 documented clades (clades III and VIII), including 2 new haplotypes (CmP243.1 and CmP244.1) and 3 previously reported haplotypes (CmP18.1, CmP19.1, CmP20.1). These results were combined with previously published mtDNA data for the Qilianyu cluster and nearby (~93 km) Yongle Islands indicating a lack of differentiation based on truncated 384 bp control region sequences (exact test, p = 0.0997; FST = 0.015, p = 0.2760), to represent a single Xisha Islands rookery. The rookery at the Xisha Islands was significantly differentiated (p < 0.01) from all 19 management units (MUs) documented in the Indo-Pacific and Japan regions, supporting recognition of the Xisha Islands rookery as a new independent MU. The results will help inform national and international conservation action plans by China and the countries around the South China Sea to protect green turtles in the West Pacific Ocean.

Adult female sea turtles are highly migratory, moving between foraging and nesting areas that can be thousands of kilometers apart. Conserving sea turtles and their habitats therefore depends on knowledge of space use across these migration-linked environments. Here, we describe migratory behavior of hawksbill sea turtles (Eretmochelys imbricata), a globally imperiled species. We used satellite telemetry to characterize the movements of females from nesting areas in Jamaica (n = 4) and Antigua (n = 4), West Indies, over 1998-2001. We mapped migrations and summarized space use during inter-nesting and for-aging periods with kernel utilization distributions (UDs) and minimum convex polygons. Seven of eight turtles made post-nesting migrations, with paths ranging 56-1324 km in length, representing straight-line displacements of 68-1206 km. Two turtles sampled in southern Jamaica made short-range migrations within southern Jamaican waters, whereas two from northern Jamaica migrated further to foraging areas in the waters of Belize and Honduras. Three migrants sampled at Long Island, Antigua migrated to St. Eustatius, St. Kitts, and Redonda, respectively, with a fourth individual remaining resident in northeastern Antigua. Inter-nesting movements observed for three turtles produced 50% UDs ranging 12-44 km2, with centroid depths between 4-13 m. Foraging UDs for seven turtles spanned 8-111 km2 and 2-161 m in depth. Our results reveal variable migratory strategies, demonstrate international connectivity between hawksbill foraging and nesting habitats, and provide important information for Caribbean conservation efforts such as the design of protected areas or fisheries policies.

Aim Understanding the spatial ecology of animal movements is a critical element in conserving long-lived, highly mobile marine species. Analyzing networks developed from movements of six sea turtle species reveals marine connectivity and can help prioritize conservation efforts. Location Global. Methods We collated telemetry data from 1235 individuals and reviewed the literature to determine our dataset's representativeness. We used the telemetry data to develop spatial networks at different scales to examine areas, connections, and their geographic arrangement. We used graph theory metrics to compare networks across regions and species and to identify the role of important areas and connections. Results Relevant literature and citations for data used in this study had very little overlap. Network analysis showed that sampling effort influenced network structure, and the arrangement of areas and connections for most networks was complex. However, important areas and connections identified by graph theory metrics can be different than areas of high data density. For the global network, marine regions in the Mediterranean had high closeness, while links with high betweenness among marine regions in the South Atlantic were critical for maintaining connectivity. Comparisons among species-specific networks showed that functional connectivity was related to movement ecology, resulting in networks composed of different areas and links. Main conclusions Network analysis identified the structure and functional connectivity of the sea turtles in our sample at multiple scales. These network characteristics could help guide the coordination of management strategies for wide-ranging animals throughout their geographic extent. Most networks had complex structures that can contribute to greater robustness but may be more difficult to manage changes when compared to simpler forms. Area-based conservation measures would benefit sea turtle populations when directed toward areas with high closeness dominating network function. Promoting seascape connectivity of links with high betweenness would decrease network vulnerability.

Hawksbill sea turtlesEretmochelys imbricatainhabiting the Hawaiian Islands are extremely rare and listed as endangered under the US Endangered Species Act. The paucity of data on basic hawksbill ecology continues to hinder effective management of the species. We analyzed stranding data collected between 1984 and 2018 to gain insights into the distribution, demography, and conservation challenges facing hawksbills in Hawai‘i. In doing so, we present a comprehensive description of the population across developmental stages and rank threats that may be impeding their successful recovery. Over the >30 yr data set, we recorded a total of only 111 juvenile and adult hawksbill stranding events. Interactions with nearshore recreational fishing gear were documented for a large proportion (48.6%) of stranding events in the Hawaiian Islands, identifying this as the primary management challenge for the species. Stranding events were biased towards females (female to male sex ratio of 4.8:1.0), which may be indicative of the population as a whole. Even though the majority of hawksbills nest on the islands of Hawai‘i Moloka‘i, and Maui, the greatest number of juvenile to adult strandings was found to be on the island of Oahu (n = 47). Temporal distribution of the majority of adult hawksbill strandings (72.2%) occurred during a 4 mo period between June and September. We discuss these and other findings that help identify future research and conservation efforts to mitigate anthropogenic threats in Hawai‘i for this enigmatic population.

Halogenated organic compounds (HOCs) in marine species collected from the Atlantic Ocean [3 shortfin mako (Isurus oxyrinchus) and 1 porbeagle (Lamna nasus)], and 12 sea turtles collected from the Pacific Ocean [3 loggerhead (Caretta caretta), 3 green (Chelonia mydas), 3 olive ridley (Lepidochelys olivacea), and 3 hawksbill (Eretmochelys imbricata)] were analyzed with a nontargeted analytical method using two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry. Sharks and sea turtles had distinct HOC profiles. Halogenated methoxyphenols (halo-MeOPs) were the most abundant compound class identified in sea turtle livers, while polychlorinated biphenyls (PCBs) were the most abundant in shark livers. In addition to legacy contaminants and halo-MeOPs, a total of 110 nontargeted/novel HOCs (NHOCs) were observed in the shark livers. Shortfin mako collected from the northern Gulf of Mexico contained the largest number (89) and most diverse structural classes of NHOCs. Among all NHOCs, a group of compounds with the elemental composition C14H12-nCln (n = 5-8) exhibited the highest concentrations, followed by chlorocarbazoles and tris(chlorophenyl) methanes (TCPMs). Using nontargeted workflows, a variety of known and unknown HOCs were observed, which demonstrate the need to develop more complete chemical profiles in the marine environment.

Perfluorinated alkyl substances (PFASs) are global, persistent, and toxic contaminants. We assessed PFAS concentrations in green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles from the North Pacific. Fifteen compounds were quantified via liquid chromatography tandem mass spectrometry from 62 green turtle and 6 hawksbill plasma samples from Hawai'i, Palmyra Atoll, and the Northern Marianas Islands. Plasma from 14 green turtles severely afflicted with fibropapillomatosis, and eggs from 12 Hawaiian hawksbill nests from 7 females were analyzed. Perfluorooctane sulfonate (PFOS) predominated in green turtle plasma; perfluorononanoic acid (PFNA) predominated in hawksbill tissues. Concentrations were greater in hawksbill than green turtle plasma (p < 0.05), related to trophic differences. Green turtle plasma PFOS concentrations were related to human populations from highest to lowest: Hawai'i, Marianas, Palmyra. Influence on fibropapillomatosis was not evident. PFASs were maternally transferred to hawksbill eggs, with decreasing concentrations with distance from airports and with clutch order from one female. A risk assessment of PFOS showed concern for immunosuppression in Kailua green turtles and alarming concern for hawksbill developmental toxicity. Perfluoroundecanoic (PFUnA) and perfluorotridecanoic (PFTriA) acid levels were correlated with reduced emergence success (p < 0.05). Studies to further examine PFAS effects on sea turtle development would be beneficial.