Large-Scale Patterns of Green Turtle Trophic Ecology in the Eastern Pacific Oceans

Trophic position and niche width are fundamental components of a species\u27 ecology, reflecting resource use, and influencing key demographic parameters such as somatic growth, maturation, and survival. Concepts about a species\u27 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 (delta C-13 and delta N-15 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 similar to 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 delta N-15 values to determine trophic position (TP). Substantial variability in bulk tissue delta C-13 and delta N-15 values was found within and among sites, and amino acid delta N-15 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 delta C-13 and delta N-15 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

Anidación de la tortuga Dermochelys coriacea (Testudines: Dermochelyidae) en playa Gandoca, Costa Rica (1990 a 1997)

La anidación de la tortuga baula fue estudiada en playa Gandoca, una importante playa de anidación de tortugas marinas localizada al sureste de la costa Caribeña de Costa Rica, dentro de los límites del Refugio Nacional de Vida Silvestre Gandoca/Manzanillo (82° 37' O, 09° 37' N). Entre 1990 y 1997, se desarrollaron campañas de observación de la anidación entre los meses de febrero a julio de cada año; 16 variables de la anidación fueron anotadas y una parte de la colonia fue marcada con marcas monel y 3 484 nidos fueron encontrados; durante este periodo se depositaron un promedio de 534 nidos por temporada, 1,135 nidos fue el máximo de anidación anual, mientras que 226 nidos fue el mínimo, el 20.8% de los nidos fueron relocalizados en los viveros. El promedio de la longitud curva del caparazón de las hembras fue de 154.65 cm y el promedio del ancho curvo del caparazón fue de 112.83 cm. Las observaciones mostraron que el promedio de huevos normales para este periodo fue de 79.28, mientras que el promedio de huevos vanos fue de 35. La recolección ilegal de huevos, la basura sobre la playa y la erosión intensiva son parte de los problemas más importantes que están causando el declive de las tortugas en Gandoca.<br>The nesting of the leatherback sea turtle was studied in Gandoca Beach, an important nesting beach on the southeastern Caribbean coast of Costa Rica, in the Gandoca/Manzanillo National Wildlife Refuge. Nesting was recorded from 1990 to 1997 (each February through July). Nesting peaked in April and May (depending on the year); 16 biological paramenters were recorded and part of the rookery was tagged with monel tags. During this period 1 045 females were studied and 3 484 nests were recorded; 534 nests was the yearly mean, (range 226-1 135), 20.8 % of the nests were relocated to hatcheries, as a conservation effort to prevent loss of nests. Mean curve carapace length was 154.65 cm and width 112.83 cm. Mean normal number of eggs/nest was 79.28 and 35 yolkless. Each turtle laid an average of 2.5 nests per season with an internesting interval of 9 days. In 1997, 39% of the nesting females had been previously tagged in Gandoca Beach and a few also in Colombia (Urabá Gulf), Pacuare and Tortuguero (Costa Rica). Poaching activity, beach debris and extensive erosion represent the main hazards that are leading to a decline of the sea turtles in Gandoca

Anidación de la tortuga Dermochelys coriacea (Testudines: Dermochelyidae) en playa Gandoca, Costa Rica (1990 a 1997)

The nesting of the leatherback sea turtle was studied in Gandoca Beach, an important nesting beach on the southeastern Caribbean coast of Costa Rica, in the Gandoca/Manzanillo National Wildlife Refuge. Nesting was recorded from 1990 to 1997 (each February through July). Nesting peaked in April and May (depending on the year); 16 biological paramenters were recorded and part of the rookery was tagged with monel tags. During this period 1 045 females were studied and 3 484 nests were recorded; 534 nests was the yearly mean, (range 226-1 135), 20.8 % of the nests were relocated to hatcheries, as a conservation effort to prevent loss of nests. Mean curve carapace length was 154.65 cm and width 112.83 cm. Mean normal number of eggs/nest was 79.28 and 35 yolkless. Each turtle laid an average of 2.5 nests per season with an internesting interval of 9 days. In 1997, 39% of the nesting females had been previously tagged in Gandoca Beach and a few also in Colombia (Urabá Gulf), Pacuare and Tortuguero (Costa Rica). Poaching activity, beach debris and extensive erosion represent the main hazards that are leading to a decline of the sea turtles in Gandoca.La anidación de la tortuga baula fue estudiada en playa Gandoca, una importante playa de anidación de tortugas marinas localizada al sureste de la costa Caribeña de Costa Rica, dentro de los límites del Refugio Nacional de Vida Silvestre Gandoca/Manzanillo (82° 37´ W, 09° 37´ N). Entre 1990 y 1997, se desarrollaron campañas de observación de la anidación entre los meses de febrero a julio de cada año; 16 variables de la anidación fueron anotadas y una parte de la colonia fue marcada con marcas monel y 3 484 nidos fueron encontrados; durante este periodo se depositaron un promedio de 534 nidos por temporada, 1,135 nidos fue el máximo de anidación anual, mientras que 226 nidos fue el mínimo, el 20.8% de los nidos fueron relocalizados en los viveros. El promedio de la longitud curva del caparazón de las hembras fue de 154.65 cm y el promedio del ancho curvo del caparazón fue de 112.83 cm. Las observaciones mostraron que el promedio de huevos normales para este periodo fue de 79.28, mientras que el promedio de huevos vanos fue de 35. La recolección ilegal de huevos, la basura sobre la playa y la erosión intensiva son parte de los problemas más importantes que están causando el declive de las tortugas en Gandoca

Golfo Dulce, Costa Rica, un área importante de alimentación para la tortuga carey del Pacífico Oriental (Eretmochelys imbricata)

Limited quantitative information is available for hawksbill turtles (Eretmochelys imbricata) at foraging grounds in the Eastern Tropical Pacific (ETP), where the species composes one of the most endangered marine turtle populations on the planet. Between August 2010 and March 2013 we captured individual hawksbill turtles using entanglement nets along the edges of mangroves and seagrasses of the Golfo Dulce, in southwest Pacific Costa Rica. A total of 62 hawksbills were captured, including 14 recaptures, of which 46 (74.19%) were juveniles (CCL&lt;66cm) and 16 (25.81%) were adults. The catch per unit effort (1 unit: 100m of net for 7h) during the study ranged between 0.03 and 0.07. The Golfo Dulce is highly turbid during the rainy season (May-November), particularly at our study area, as high sediment loads due to intensive runoff lead to poor water clarity. The probability of detection of hawksbills was considerably higher in the dry season (December-April) compared to the rainy season, suggesting these turtles may prefer waters with higher clarity. None of the individuals captured had evidence of internal or external tags, making it possible to conclude that they had not been previously marked at other feeding or breeding sites. A total of 28 (45.16%) individuals were found to host the ectoparasitic barnacle Stephanolepas muricata, which in high concentrations can be harmful by limiting the mobility of organs and limbs. Although consistent in-water quantification of hawksbills in the ETP remains scant, this study represents the longest and most robust marine monitoring dataset for hawksbills in the region to date. Our findings highlight the relevance of the Golfo Dulce as an important foraging ground for hawksbill turtles in the ETP and emphasize the need to monitor and protect this habitat to aid efforts to recover this critically endangered marine turtle population.  La información cuantitativa disponible es escasa para la tortuga carey (Eretmochelys imbricata) en zonas de alimentación en el Pacifico Oriental, donde esta especie representa una de las poblaciones de tortugas marinas más amenazadas del mundo. Entre agosto de 2010 y marzo de 2013 capturamos individuos de tortuga carey utilizando redes de enmalle en los bordes de los manglares y los pastos marinos del Golfo Dulce, Costa Rica. Un total de 62 tortugas carey fueron capturadas, incluyendo 14 recapturas, de las cuales 46 (74.19 %) fueron juveniles (LCC&lt;66cm) y 16 (25.81) fueron adultas. La captura por unidad de esfuerzo (CPUE, 1 unidad: 100m de red por 7h) durante el estudio oscilo entre 0.03 y 0.07. El Golfo Dulces es altamente turbio durante la época lluviosa (mayo-noviembre), particularmente en nuestra área de estudio, debido a la intensa escorrentía que acarrea sedimentos que producen aguas poco cristalinas. La probabilidad de detección de tortugas carey fue considerablemente superior en la época seca (diciembre - abril) comparado con la época lluviosa, lo que sugiere que las tortugas prefieren hábitats con aguas cristalinas. Ninguna de las tortugas capturadas presentaba marcas externas o internas que hicieran concluir que habían sido marcadas en otros sitios de alimentación o reproducción. Un total de 28 (45.16%) individuos fueron hospederos de un ectoparásito (Stephanolepas muricata), el cual puede ser dañino en altas concentraciones al limitar la movilidad de órganos y extremidades. A pesar de que el registro de tortugas carey en agua sigue siendo escaso en el Pacífico Tropical, hasta la fecha este estudio representa el conjunto de datos de monitoreo más largo y robusto para la especie en la región. Nuestros resultados demuestran la relevancia del Golfo Dulce como sitio de alimentación importante para la tortuga carey en el Pacífico Oriental y enfatiza en la necesidad de monitorear y proteger este hábitat, para ayudar a la recuperación de esta población de tortugas marinas que esta críticamente amenazada.

Reproductive hormonal profile in Eastern Pacific green turtles captured in‐water

The Eastern Pacifc green turtle (EPGT) has been diferentiating from the green turtle and is currently considered a separate population. This study determined the values of reproductive hormones and total thyroxine of 56 resident foraging green turtles captured between 2012 and 2014 at Golfo Dulce, Costa Rica. All of them underwent a physical examination and were deemed as healthy individuals. The progesterone values were 0.31–2.723 ng/ml, estradiol 25.54–104.129 pg/ml, testosterone 1.94–228.97 ng/dl, and thyroxine 0.5–0.9 μg/dl. Since our population did not show sexual dimorphism, and the curved cara- pace length sizes did not match previous reports, turtles’ sex was determined based on high testosterone concentrations. Our results showed that 48 males (>3 ng/dl), three females (<2 ng/dl), and fve yet undetermined individuals (2–3 ng/dl) were sampled. The green turtle populations at the Golfo Dulce seem to be formed by subpopulations at diferent stages of their reproductive cycle; among them could be males and females close to mating season, foraging females between seasons and sub-adults in their fnal developing habitat. The sampled population included 3 juveniles (one male and two not defned), 45 sub-adults (40 males, three females and one not determined), 7 adults (all males), and one undetermined individual (not sex determined either). The progesterone results indicated that none of the females were nesting; this might indicate that they nest far from the area. The information provided by this study is extremely valuable in the attempts to determine the health status for conservation programs of EPGT in the area.La tortuga verde del Pacífico Oriental (EPGT) se ha ido diferenciando de la tortuga verde y actualmente se considera una población separada. separada. Este estudio determinó los valores de hormonas reproductivas y tiroxina total de 56 tortugas verdes residentes capturadas entre 2012 y 2014 en Golfo Dulce, Costa Rica. residentes capturadas entre 2012 y 2014 en el Golfo Dulce, Costa Rica. A todas ellas se les realizó un examen físico y fueron considerados individuos sanos. Los valores de progesterona fueron 0,31-2,723 ng/ml, estradiol 25,54-104,129 pg/ml, testosterona 1,94-228,97 ng/dl, y tiroxina 0,5-0,9 µg/dl. Dado que nuestra población no mostraba dimorfismo sexual, y que los tamaños curvos de la longitud del caparazón no coincidían con informes anteriores, el sexo de las tortugas se determinó basándose en las altas concentraciones de testosterona. Nuestros resultados en resultados mostraron que se muestrearon 48 machos (>3 ng/dl), tres hembras (<2 ng/dl) y cinco individuos aún indeterminados (2-3 ng/dl). muestreados. Las poblaciones de tortuga verde en el Golfo Dulce parecen estar formadas por subpoblaciones en diferentes etapas de su ciclo reproductivo. de su ciclo reproductivo; entre ellas podría haber machos y hembras cerca de la temporada de apareamiento, hembras forrajeras entre temporadas y subadultos en su hábitat de desarrollo final. La población muestreada incluía 3 juveniles (un macho y dos no definidos), 45 subadultos (40 machos, tres hembras y uno no determinado), 7 adultos (todos machos) y un individuo indeterminado (tampoco se determinó el sexo). determinado). Los resultados de la progesterona indicaron que ninguna de las hembras estaba anidando; esto podría indicar que anidan lejos de la zona. La información proporcionada por este estudio es extremadamente valiosa en los intentos de determinar el estado de salud estado de salud para los programas de conservación del EPGT en la zona.Universidad Nacional, Costa Rica.Escuela de Medicina Veterinari

Sand and incubation temperatures in a sea turtle nesting beach at the Cayos de San Felipe National Park, Pinar del Río, Cuba, during the 2012-2013 season/ Temperatura de la arena y de incubación en una playa de anidación de tortugas marinas en el Parque Nacional Cayos de San Felipe, Pinar del Río, Cuba, durante la temporada 2012-2013

Sand temperature at 50 cm depth was measured in three profiles along El Sijú nesting beach, Cayos de San Felipe National Park, Pinar del Río, Cuba during the 2012-2013 nesting season. Sand and incubation temperatures inside and close to nests of Hawksbill (Eret- mochelys imbricata), Loggerhead (Caretta caretta) and Green turtle (Chelonia mydas) were also measured. We compared sand temper- atures among locations with different environmental conditions as well as incubation and sand temperatures during the thermo-sen- sitive period. Using regression analysis, we modelled expected nest temperature from sand temperature for assessing the feasibility of using the latter as a proxy for estimating nesting temperature. Temperature at 50 cm depth of all locations during summer were significantly higher than pivotal while in winter it was significantly lower even in sunny areas. Average sand temperature during the peaks of the nesting seasons of the three species were significantly different (F the hottest= 942.39, p <0.01), with Green turtle season being pivotal temperature. Mean incubation temperatures in nests of C. mydas and C. caretta were higher than those of E. imbricata. Nests incubated during winter (all of E. imbricata) generally became cooler as the winter advanced (F (5,105) = 47.07, p < 0.001), while those incubated during the period of July to October (summer) had mean temperatures above 30.5°C irrespective of the species. We found significant positive differences in the thermo- sensitive period between nest and pivotal temperatures in four (the three species) and negative in two (E. imbricata) out of eight nests. Furthermore, sand temperature during nesting was significantly higher than 29.2°C in four out of the six nests sampled. These re- sults point out a possible skew in hatchlings sex proportion towards females mainly during summer time, when the peak of C. mydas´nesting season occurs. The difference between daily average of nest and sand temperatures increased as the incubation progressed. When modelling expected differences and estimat- ing nest temperatures accordingly, we found strong, significant linear relation (r = 0.91, p<0.05) and no significant differences between observed and estimated temperatures (t = 0.96, p = 0.34). Moreover, we were able to es- timate nest temperature with good accuracy (R2=0.83, average error=± 0.35ºC), which indi- cates that sand temperature could be a good proxy for determining average nest tempera- ture during the middle third of the incubation period, which can provide clues about the oc- currence of sex biases. RESUMEN Se midió la temperatura de la arena a 50 cm de profundidad (profundidad de anidación promedio) a lo largo de tres perfiles de la playa de anidación de tortugas marinas El Sijú, par- que nacional Cayos de San Felipe, Pinar del Río, Cuba durante la temporada de anidación 2012-2013. Además, se midió la temperatura en la arena y de incubación en nidos de carey (Eretmochelys imbricata), caguama (Caretta caretta) y tortuga verde (Chelonia mydas). Se comparó la temperatura de la arena en dife- rentes posiciones con respecto a las condicio- nes ambientales así como la diferencia entre la temperatura de incubación y la dela arenas durante el período termo-sensible. Usando un análisis de regresión, se modeló la temperatu- ra esperada del nido estimada a partir de la temperatura de la arena para determinar la factibilidad de usar esta última como proxy para futuras estimaciones de la temperatura en el nido. La temperatura en los perfiles en todos los puntos medidos durante el verano fue superior a la pivote, mientras que en invierno fue significativamente menor, incluso en las áreas soleadas. La temperatura de la arena promedio durante el pico reproductivo de las tres especies fue significativamente diferente (F (2,1214) = 942.39, p <0.01), ya que la temporada de tortuga verde tuvo los valores más altos muy por encima de la temperatura pivote. La temperatura de incubación en nidos de C. mydas y C. caretta fueron mayores que en los de E. imbricata. Los nidos incubados duran- te el invierno (todos de E. imbricata) general- mente redujeron gradualmente la temperatura con el avance del invierno (F(5,105) = 47.07, p < 0.001), los incubaos en el período de julio a octubre, en cambio, tuvieron temperaturas de incubación por encima de los 30.5°C con inde- pendencia de la especie. Se encontraron dife- rencias significativas y positivas entre la tem- peratura del nido y la pivote durante el período termo-sensible en cuatro nidos (de las tres es- pecies) y negativas en dos nidos (E. imbricata) de los ocho analizados. Más aún, la tempera- tura de la arena durante también fue superior a 29.2°C en cuatro de los seis nidos evaluados. Estos resultados apuntan a un posible sesgo en la proporción sexual en las crías con mayor número de hembras durante el verano, cuando ocurre el pico de C. mydas. La diferencia entre la temperatura diaria del nido y de la arena se incrementó con el desarrollo embrionario. Cuando se modeló la diferencia esperadas y se estimó la temperatura tomando esto en consi- deración, se encontró una relación lineal fuerte y significativa (r = 0.91, p <0.05) y la ausencia de diferencias significativas entre los valores observados y los estimados (t = 0.96, p = 0.34). Más aún, se pudo estimar la temperatura con una buena exactitud (R2=0.83, error medio=± 0.35ºC), lo que indica que la temperatura de la arena puede ser un buen proxy para determi- nar la temperatura del nido durante el segun- do tercio del período de incubación, para utili- zarla en la estimación de la proporción sexual esperada en estos nidos

Blood parameters of the Eastern Pacific green turtle (Chelonia mydas) foraging in the Golfo Dulce, Costa Rica

The Eastern Pacifc green turtle (EPGT) has been diferentiating from the green turtle and is currently being considered a separate population. In this study, values for hematology and biochemistry of 85 green turtles captured from 2010 to 2014 were analyzed. These animals correspond to a resident foraging population at Golfo Dulce, Costa Rica. All of them underwent a physical examination and were deemed apparently healthy. Hematological analyses were done using manual methods, while seric metabolites were determined with automated and semi-automated spectrophotometry. According to the curved carapace length (CCL) measurements, the subadult individuals were the most frequent (n=74). The predominant cells were heterophils, followed by lymphocytes. Basophils were observed in 75% of the slides and in a proportion as high as 43%. Up to 80 samples were analyzed for the following seric parameters: total protein (2.6–6.2 g/dL), albumin (1–2.7 g/ dL), globulin (1.2–4.1 g/dL), glucose (54–145 mg/dL), cholesterol (58–336 mg/dL), ureic nitrogen (0–12 g/dL), creatinine (0.1–0.7 mg/dl), phosphorus (3.4–17 mg/dl), calcium (4.9–10.2 mg/dl), magnesium (5.2–12.8 mg/dl), uric acid (0.1–2.8 mg/ dL), triglycerides (14–743 mg/dl), alanine aminotransferase (0–13 U/L), aspartate aminotransferase (82–289 U/L) and seric alkaline phosphatase (41–1263 U/L). These data can aid health status and conservation programs for the EPGT in this and nearby, similar locations.La tortuga verde del Pacífico Oriental (EPGT) se ha ido diferenciando de la tortuga verde y actualmente se considera una población separada. En este estudio se analizaron los valores de hematología y bioquímica de 85 tortugas verdes capturadas entre 2010 y 2014. Estos animales corresponden a una población residente de forrajeo en Golfo Dulce, Costa Rica. A todos ellos se les realizó un examen físico y fueron considerados aparentemente sanos. Los análisis hematológicos se realizaron con métodos manuales, mientras que los metabolitos séricos se determinaron con espectrofotometría automatizada y semiautomatizada. Según las mediciones de la longitud curvada del caparazón (LCC), los individuos subadultos fueron los más frecuentes (n=74). Las células predominantes eran los heterófilos, seguidos de los linfocitos. Los basófilos se observaron en el 75% de los portaobjetos y en una proporción tan elevada como el 43%. Se analizaron hasta 80 muestras para determinar los siguientes parámetros séricos: proteínas totales (2,6-6,2 g/dL), albúmina (1-2,7 g/ dL), globulina (1,2-4,1 g/dL), glucosa (54-145 mg/dL), colesterol (58-336 mg/dL), nitrógeno ureico (0-12 g/dL), creatinina (0,1-0,7 mg/dL), fósforo (3. 4-17 mg/dl), calcio (4,9-10,2 mg/dl), magnesio (5,2-12,8 mg/dl), ácido úrico (0,1-2,8 mg/ dL), triglicéridos (14-743 mg/dl), alanina aminotransferasa (0-13 U/L), aspartato aminotransferasa (82-289 U/L) y fosfatasa alcalina sérica (41-1263 U/L). Estos datos pueden servir de ayuda para los programas de conservación y estado sanitario del GEPT en esta localidad y en otras similares cercanas.Universidad Nacional, Costa Rica.Escuela de Medicina Veterinari

Quantifying illegal extraction of sea turtles in Costa Rica

Estimates of illegal wildlife trade vary significantly and are often based on incomplete datasets, inferences from CITES permits or customs seizures. As a result, annual global estimates of illegal wildlife trade can vary by several billions of US dollars. Translating these figures into species extraction rates is equally challenging, and estimating illegal take accurately is not achievable for many species. Due to their nesting strategies that allow for census data collection, sea turtles offer an exception. On the Caribbean coast of Costa Rica, three sea turtle species (leatherback, Dermochelys coriacea; green, Chelonia mydas; and hawksbill, Eretmochelys imbricata) are exploited by poachers. Despite the consumption of turtle eggs and meat being illegal, they are consumed as a cultural food source and seasonal treat. Conservation programmes monitor nesting beaches, collect abundance data and record poaching events. Despite the availability of robust long-term datasets, quantifying the rate of poaching has yet to be undertaken. Using data from the globally important nesting beach, Tortuguero, as well as beaches Playa Norte and Pacuare on the Caribbean coast of Costa Rica, we modelled the spatial and temporal distribution of poaching of the three sea turtle species. Here, we present data from 2006 to 2019 on a stretch of coastline covering c.37 km. We identified poaching hotspots that correlated with populated areas. While the poaching hotspots persisted over time, we found poaching is declining at each of our sites. However, we urge caution when interpreting this result as the impact of poaching varies between species. Given their low abundance on these beaches, the poaching pressure on leatherback and hawksbill turtles is far greater than the impact on the abundant green turtles. We attribute the decline in poaching to supply-side conservation interventions in place at these beaches. Finally, we highlight the value of data sharing and collaborations between conservation NGOs.</p

Data from: Pan-Atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries

Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters