Inter-nesting Habitat Research Articles

Inter-nesting habitat use by green turtles Chelonia mydas in the Great Barrier Reef

Inter-nesting habitat use by green turtles Chelonia mydas in the Great Barrier Reef

Inter-nesting, migration, and foraging behaviors of green turtles (Chelonia mydas) in the central-southern Red Sea

Sea turtles are migratory with nesting and foraging areas in distinct and often widely separated habitats. Telemetry has been a vital tool for tracking sea turtle migrations between these areas, but tagging efforts are often focused on only a few large rookeries in a given region. For instance, turtle tagging in the Red Sea has been focused in the north of the basin. We tagged five green turtles (Chelonia mydas) at a nesting site in the central-southern Red Sea and tracked them for 72–243 days. During the inter-nesting period, the turtles showed high site-fidelity, with a maximum home range of 161 km2. After the nesting season, the turtles migrated up to 1100 km to five distinct foraging locations in three countries (Saudi Arabia, Sudan, and Eritrea). Movements within foraging habitats were more wide-ranging compared to inter-nesting movements, with home ranges varying between 1.19 and 931 km2. The tracking data revealed that the creation of a relatively small marine reserve could protect the critical inter-nesting habitat in the Farasan Banks. The results also highlight the need for multinational collaboration to protect migratory corridors and foraging sites of this endangered species.

Mediterranean green turtle population recovery increasingly depends on Lake Bardawil, Egypt

To assign conservation status to a population, its size, trends, and distribution must be estimated. The Mediterranean green turtle population has shown signs of recovering over the past decade, likely in response to nest protection, but satellite tracking suggests adult foraging remains largely restricted to only a few key sites in the eastern Mediterranean. Previous research suggested that the majority of green turtles nesting at an important rookery in Cyprus, forage in Lake Bardawil, Egypt making an observed population increase dependent on this important site, which is under a high degree of anthropogenic maintenance. Here we provide new data that further demonstrates the importance of Lake Bardawil to green turtles that nest at other major rookeries on Cyprus, in the Karpaz Peninsula, with 74 % of satellite tracked females (n = 19) migrating to this key site. We also report on the first systematic nest counts for this area in over two decades and identify the inter-nesting habitat used by females nesting at these important beaches on the north and south coasts of the Peninsula. Comparing the oldest available 3-year nest count averages (1993–1995), with nest counts undertaken as part of this study (2017–2019), mean annual nest numbers increased from 186 to 554, an increase of 198 %. Our data confirm the continued importance of these beaches for the Mediterranean green turtle population and underscore the reliance of this endangered population on a man-made lagoon for recent increases in clutch counts at monitored beaches. The results highlight the utility of satellite telemetry to inform conservation status assessments and establishing conservation at both nesting and foraging sites across the population.

Satellite Tracking Reveals Nesting Patterns, Site Fidelity, and Potential Impacts of Warming on Major Green Turtle Rookeries in the Red Sea

Major aggregations of nesting green turtles (Chelonia mydas) occur in the northern Red Sea, although little is known about the reproductive ecology of this endangered species in the region. To address this issue, we satellite-tracked 30 female green turtles to document their movements and to identify factors driving habitat use at two major rookeries in the Red Sea, Jazirat Mashabah (Mashabah Island) and Ras Al Baridi in Saudi Arabia. Between successive nesting events, turtles displayed high fidelity to nesting beaches and adjacent in-water habitats (inter-nesting habitats). Using generalized linear mixed models, we estimated the mean probability of nesting per beach emergence (nesting success rate) to be 0.628, and the mean duration between a successful nesting event and the successive emergence onto the beach (re-nesting interval) to be 10.8 days at each site. The nesting success rate was relatively high (>0.8) when the preceding daytime land surface temperature (LST) was lower than 37°C but decreased with elevated daytime LST (<0.4 when >47°C). Re-nesting interval was longer at lower water temperatures and towards the end of the nesting season of individuals. Our study improves the robustness of abundance estimates from census data (e.g., track counts) and shows that the protection of nesting and inter-nesting habitats during a breeding season would be an effective conservation strategy for the species. We discuss how global warming could increase energy expenditure due to lowered nesting success, ultimately compromising the reproductive fitness of these populations.

Satellite tracking improves conservation outcomes for nesting hawksbill turtles in Solomon Islands

The remote tracking of endangered animals is often justified by the application of movement data to conservation problems, but examples of where scientific findings have rapidly informed conservation actions are relatively rare. In this study we satellite tracked 30 adult female hawksbill turtles (Eretmochelys imbricata) that were captured after nesting in the Arnavon Community Marine Park (ACMP), Solomon Islands. Ten hawksbill turtles were tagged in April 2016, ten in May 2017 and ten in November 2018. Our primary aim was to determine if the ACMP boundaries that were demarcated in 1995 were large enough to protect female hawksbill turtles throughout their entire nesting season. Our home range analysis revealed that collectively, tracked hawksbill turtles spent 98.5% of their inter-nesting season within the ACMP, confirming that the original park boundaries were adequate. Our first year's results were shared with community and government stakeholders and assisted in getting the ACMP declared as the Solomon Islands first national park in May 2017. Our fine scale analysis of inter-nesting habitats also highlighted that most hawksbill turtle nests were being laid on an island in the ACMP that did not have a permanent ranger presence and was experiencing persistent poaching. Based on this finding an additional ranger station was established on this uninhabited island and staffed with community rangers in 2017. Our study demonstrates how involving community, government and NGO stakeholders in applied research can lead to results being rapidly utilised to inform policy and conservation practice as soon as they become available.

Rapid Assessments of Leatherback Small-Scale Fishery Bycatch in Internesting Areas in the Eastern Pacific Ocean

The East Pacific (EP) leatherback population is listed by the IUCN Red List of Threatened species as Critically Endangered. Despite conservation efforts, mainly focused around nesting areas, its population has declined by over 90% since the 1980s. The major current threat is fisheries bycatch, but its impact has been primary documented within South American migration and foraging habitats, with scarce information from nesting or interesting areas. To assess the impact of small-scale fisheries on EP leatherbacks inhabiting waters north of the equator we conducted rapid bycatch assessments (surveys) in 5 countries (México, Nicaragua, Costa Rica, Panamá and Colombia), some of which host the main EP leatherback nesting areas. A total of 1,778 surveys were conducted across 79 fishing ports (México = 37, Nicaragua = 6, Costa Rica = 5, Panamá = 17 and Colombia = 14). Leatherback bycatch was reported in all countries, and in 54% of ports surveyed by 7% (n = 125) of fishers interviewed. Surveys enabled identification of areas near nesting beaches (e.g. inter-nesting habitats) where leatherback bycatch was higher and periods during which fisheries interactions events were more frequent. Bycatch events were most frequently reported in gillnets and longlines using “J” hook. Data were scaled up across fishing fleets to estimate that 345 (± 210) individual leatherbacks are caught annually in the ports surveyed. Our study provides a first evaluation of leatherback bycatch by small-scale fisheries in countries of the eastern Pacific Ocean where leatherbacks nest, and it highlights areas close to index nesting beaches where conservation efforts targeting bycatch reduction and bycatch mortality may be focused.

Off-the-shelf GPS technology to inform marine protected areas for marine turtles

The financial expense of tracking solutions often impedes effective characterisation of habitat use in threatened marine megavertebrates. Yet some of these taxa predictably aggregate at coastal breeding sites, providing conservation opportunities. Toward a low-cost solution for tracking marine megavertebrates, we trial conventional GPS data loggers against Argos satellite transmitters for assessing inter-nesting habitat use of marine turtles. Devices were attached to green (Chelonia mydas) and loggerhead (Caretta caretta) turtles nesting at a study site in Cyprus, where patrol teams were in place to retrieve GPS loggers from turtles returning to lay subsequent clutches. GPS tracking revealed loggerhead turtles to predominantly use areas outside the boundaries of an MPA proposed for the region, while both species under-used much of the MPA area. Due to high location error, Argos data were considered unsuitable for such fine-scale assessments (all location classes except Z were included in our analysis). However, Argos tracking showed half the loggerhead turtles sampled also nested outside of the patrolled study area, demonstrating connectivity with other proposed MPAs. This was not accounted for by GPS tracking, because females exhibiting this behaviour rarely returned to the study beach, precluding GPS retrieval, thus, demonstrating the power of remote data access. The low-cost GPS technology could be considered in similar cases, where recapture is likely and where funding barriers preclude the use of Argos-relay fast-acquisition GPS technology. In combining the accuracy GPS and the continuity of Argos, the latter provides the best solution in most scenarios, but at far greater cost.

Inter-nesting movements and habitat-use of adult female Kemp's ridley turtles in the Gulf of Mexico.

Species vulnerability is increased when individuals congregate in restricted areas for breeding; yet, breeding habitats are not well defined for many marine species. Identification and quantification of these breeding habitats are essential to effective conservation. Satellite telemetry and switching state-space modeling (SSM) were used to define inter-nesting habitat of endangered Kemp’s ridley turtles (Lepidochelys kempii) in the Gulf of Mexico. Turtles were outfitted with satellite transmitters after nesting at Padre Island National Seashore, Texas, USA, from 1998 through 2013 (n = 60); Rancho Nuevo, Tamaulipas, Mexico, during 2010 and 2011 (n = 11); and Tecolutla, Veracruz, Mexico, during 2012 and 2013 (n = 11). These sites span the range of nearly all nesting by this species. Inter-nesting habitat lies in a narrow band of nearshore western Gulf of Mexico waters in the USA and Mexico, with mean water depth of 14 to 19 m within a mean distance to shore of 6 to 11 km as estimated by 50% kernel density estimate, α-Hull, and minimum convex polygon methodologies. Turtles tracked during the inter-nesting period moved, on average, 17.5 km/day and a mean total distance of 398 km. Mean home ranges occupied were 725 to 2948 km2. Our results indicate that these nearshore western Gulf waters represent critical inter-nesting habitat for this species, where threats such as shrimp trawling and oil and gas platforms also occur. Up to half of all adult female Kemp’s ridleys occupy this habitat for weeks to months during each nesting season. Because inter-nesting habitat for this species is concentrated in nearshore waters of the western Gulf of Mexico in both Mexico and the USA, international collaboration is needed to protect this essential habitat and the turtles occurring within it.

Using habitat suitability models in an industrial setting: the case for internesting flatback turtles

AbstractTo predict and manage ecological impacts of anthropogenic activities effectively, an understanding of at‐risk species spatial ecology is first required. This is particularly difficult in the marine environment due to limited offshore access and wide‐ranging movements of some species. Flatback turtles are a protected species potentially at risk from hazards associated with the resource sector in Australia, yet their at‐sea spatial ecology is not well understood. We use habitat suitability modeling to identify environmental variables that influence flatback turtle internesting movement; identify areas of suitable internesting habitat; and determine overlap of identified internesting habitat with resource sector hazards. Internesting movements of 47 female flatback turtles, from five rookeries in the North West Shelf region of Western Australia, were recorded using platform terminal transmitters between 2006 and 2010. Environmental variables including sea surface temperature (SST), bathymetry, magnetic anomalies, distance from coastline, slope, and ruggedness index were combined with the tracking data from each rookery in an ecological niche model. We used the positions of resource sector vessels to represent areas of potential impact from resource sector hazards and identified overlap with suitable internesting habitat areas as a representative of the likelihood of impact. The primary environmental variables that influenced flatback internesting movement were bathymetry, distance from coastline, and SST. Suitable areas of internesting habitat were located in close proximity to many known flatback turtle rookeries across the region. Areas of suitable internesting habitat overlapped resource sector hazards in close proximity to four of the five rookeries and at other known flatback turtle rookeries. The cumulative overlap across the overall study area indicates a high potential for interaction with resource sector hazards, demonstrating the need for regional protection measures in these areas. This study provides a capability for regulators and developers to determine the potential offshore presence of internesting flatback turtles within the region, allowing for protection measures to be targeted appropriately as industrial development continues.

Habitat use and diving behaviour of gravid olive ridley sea turtles under riverine conditions in French Guiana

The identification of the inter-nesting habitat used by gravid sea turtles has become a crucial factor in their protection. Their aggregation in large groups of individuals during the inter-nesting period exposes them to increased threats to their survival - particularly along the French Guiana shield, where intense legal and illegal fisheries occur. Among the three sea turtle species nesting in French Guiana, the olive ridley appears to have the most generalist diet, showing strong behavioural plasticity according to the environment encountered. The large amounts of sediments that are continuously discharged by the Amazon River create a very unusual habitat for olive ridleys, i.e. turbid waters with low salinity. This study assesses the behavioural adjustments of 20 adult female olive ridleys under such riverine conditions. Individuals were tracked by satellite from Remire-Montjoly rookery in French Guiana using tags that recorded the location and diving parameters of individuals, as well as the immediate environment of the turtles including the in situ temperature and salinity. Data concerning potential preys was provided via collection of epifauna by a trawler. Multiple behavioural shifts were observed in both horizontal and vertical dimensions. During the first half of the inter-nesting season, the turtles moved away from the nesting beach (21.9±24.7 km), performing deeper (12.6±7.4m) and longer (29.7±21.0min) dives than during the second half of the period (7.4±7.8km, 10.4±4.9m and 25.9±19.3min). Olive ridleys remained in waters that were warm (range: 26–33°C) and which fluctuated in terms of salinity (range: 19.5–36.4psu), in a relatively small estuarine habitat covering 423km2. If olive ridleys were foraging during this period, the potential preys that might be available were mostly crustaceans (43%) and fish (39%), as expected for the diet of this generalist species during this period. This study highlights the numerous behavioural adaptations of this species in response to the unusual riverine conditions of the French Guiana continental shelf.

Inter-nesting behavioural adjustments of green turtles to an estuarine habitat in French Guiana

Sea turtles adjust their behaviour according to the conditions of their habitat, thus saving or gaining energy during the energetically costly inter-nesting season. This study aimed to investigate how gravid green turtles Chelonia mydas nesting in Suriname and French Guiana have adapted to the unusual habitat of the Maroni River estuary, which has highly turbid and low salinity waters and a priori lacks seagrass, one of the main foods consumed by this species. Satellite telemetry was used to assess the behavioural adjustments of 26 adult females in terms of (1) home range and (2) diving behaviour, by recording the movements (location, dive depth, dive duration, surface duration) and environmental conditions (temperature and salinity of the water) experienced by each individual. The turtles exhibited limited movements, occupying a core home range of 512.7 km2 and remaining close to the shore (3.8 ± 3.1 km) and the nesting beach (18.6 ± 22.7 km). Dive data showed that individuals spent extended periods at the surface (210 ± 288 min), probably associated with diurnal resting activity. The turtles performed uncharacteristically short and shallow dives (<5 min and <2 m) which could result from lung volume issues linked to positive buoyancy. This species shows a unique ability to tolerate extreme environments in this inter-nesting habitat, where large river outputs generate warm water (~27 to 29°C) and highly variable salinities (range: 1.2 to 35.5 psu). These results highlight the various behavioural adjustments of this population in response to the atypical and estuarine habitat of the Maroni river mouth.

Design of a protected area for inter-nesting hawksbills in Barbados: an evidence-based approach

To aid in the designation of a marine protected area for hawksbill sea turtles, Eretmochelys imbricata (Linnaeus, 1766), nesting at one of the largest rookeries in the Wider Caribbean Region (Needham's Point, Barbados), we elucidated key inter-nesting behaviors (i.e., the approximately 2-wk period of time spent at sea between nesting events) from published spatial, diving, and habitat utilization data, and the areas of overlap and potential conflict with anthropogenic uses of the coastal zone. Historically, much of the focus of conservation efforts for this species has been on protecting breeding females and their eggs from harvest, and more recently protection of nesting beaches. However, protecting the habitats in which these animals spend their inter-nesting interval and addressing the indirect anthropogenic mortality they are exposed to while in these nearshore habitats has received less attention. Despite a relatively small percentage of a hawksbill's life-cycle being spent in inter-nesting habitats, the relative value of adult females for population recovery and the vulnerability associated with large aggregations of females adjacent to rookeries makes this mature stage of their life-cycle one of high conservation priority.

Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period

Nesting strategies and use of important in-water habitats for far-ranging marine turtles can be determined using satellite telemetry. Because of a lack of information on habitat-use by marine turtles in the northern Gulf of Mexico, we used satellite transmitters in 2010 through 2012 to track movements of 39 adult female breeding loggerhead turtles (Caretta caretta) tagged on nesting beaches at three sites in Florida and Alabama. During the nesting season, recaptured turtles emerged to nest 1 to 5 times, with mean distance between emergences of 27.5 km; however, several turtles nested on beaches separated by ∼250 km within a single season. Mean total distances traveled throughout inter-nesting periods for all turtles was 1422.0±930.8 km. In-water inter-nesting sites, delineated using 50% kernel density estimation (KDE), were located a mean distance of 33.0 km from land, in water with mean depth of −31.6 m; other in-water inter-nesting sites, delineated using minimum convex polygon (MCP) approach, were located a mean 13.8 km from land and in water with a mean depth of −15.8 m. Mean size of in-water inter-nesting habitats were 61.9 km2 (50% KDEs, n = 10) and 741.4 km2 (MCPs, n = 30); these areas overlapped significantly with trawling and oil and gas extraction activities. Abundance estimates for this nesting subpopulation may be inaccurate in light of how much spread there is between nests of the same individual. Further, our results also have consequences for critical habitat designations for northern Gulf loggerheads, as protection of one nesting beach would not encompass the entire range used by turtles during breeding seasons.

The behavioural choices of green turtles nesting at two environmentally different islands in Taiwan

Endangered marine animals that are capable of changing behaviour in response to different environmental conditions and still reproduce successfully may have better survival chances in the long term. Although the inter-nesting behaviour of sea turtles has been studied extensively since the development of animal borne telemetry devices, there is still much to learn about their behavioural strategies across a range of different environments. Here we compared the diving behaviour of green turtles, Chelonia mydas, nesting at two geographically distinct islands of Taiwan (Wan-an and Lanyu) using time–depth recorders. Data records for 9 out of 10 turtles (4 from Wan-an and 5 from Lanyu) revealed conformity in their “rest to save energy” behaviour by spending 55% of their time on the sea floor although suitable places at Lanyu are limited. One turtle, however, left the island's nearshore waters and made deep (≥5m down to 64m) pelagic dives during the night and shallow (<5m) diurnal dives with gliding phases during the ascent. The dive profiles resembled those recorded from green turtles during oceanic migration, and may be attributable to multiple activities including travelling, mid-water resting and, possibly, foraging at night on macroplanktonic organisms. Therefore, a heterogeneous inter-nesting habitat may provide enough resources to suit at least two different behavioural strategies that should maximise reproductive output — either “conserve energy through resting” or “gain energy through foraging”.

Satellite-tracking reveals multiple foraging strategies and threats for olive ridley turtles in Brazil

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 443:237-247 (2011) - DOI: https://doi.org/10.3354/meps09427 Satellite-tracking reveals multiple foraging strategies and threats for olive ridley turtles in Brazil Augusto C. C. D. da Silva1,*, Erik A. P. dos Santos1, Fábio L. das C. Oliveira2, Marilda I. Weber2, Jamyle A. F. Batista2, Thiago Z. Serafini3, Jaqueline C. de Castilhos2 1Centro Nacional de Conservação, Pesquisa e Manejo das Tartarugas Marinhas, ReBio Santa Isabel, 49190-000, Pirambu, SE, Brazil 2Fundação Centro Brasileiro de Proteção e Pesquisa das Tartarugas Marinhas, 49035-485, Aracaju, SE, Brazil 3Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento - MADE, Universidade Federal do Paraná—UFPR, 80035-050, Curitiba, PR, Brazil *Email: cesar@tamar.org.br ABSTRACT: The state of Sergipe in northeastern Brazil is the largest nesting area for olive ridley turtles along this nation’s coast, and constitutes a major rookery in the western Atlantic as well. Conservation efforts with a focus on nesting activities have been implemented there since 1982, but little is known about other aspects of the life cycle, specifically post-nesting movements of females and the locations of foraging grounds. To address this issue, satellite transmitters were deployed on 10 females that nested between February and April 2006. The turtles were monitored for an average of 113 d (range: 14 to 297 d), and an average movement of 1669 km (range: 407 to 4265 km) was recorded. Of the 10 turtles monitored, 6 moved along the Brazilian continental shelf to neritic foraging areas. Five of these turtles utilized foraging areas along the northern and northeastern coasts of Brazil, while one foraged along the southeastern coastline. Two females were tracked to equatorial oceanic waters, with one first moving to an inshore foraging site where she remained for 34 d before migrating to oceanic waters off the Brazilian coast. Signal transmission of 3 of the 10 turtles tracked ceased during their post-nesting migrations, preventing identification of their feeding areas. Olive ridley turtles nesting on the coast of Sergipe displayed a range of post-nesting movements including to coastal sites along the continental shelf as well as offshore oceanic areas. Inter-nesting habitats, migration routes and foraging grounds showed great overlap with a variety of coastal fisheries, as well as with longline fishing in oceanic waters, a key consideration for developing conservation strategies for this species in the western Atlantic. KEY WORDS: Satellite tracking · Inter-nesting · Migration · Foraging grounds · Lepidochelys olivacea · Conservation · Brazil Full text in pdf format PreviousNextCite this article as: da Silva ACCD, dos Santos EAP, Oliveira FLdC, Weber MI, Batista JAF, Serafini TZ, de Castilhos JC (2011) Satellite-tracking reveals multiple foraging strategies and threats for olive ridley turtles in Brazil. Mar Ecol Prog Ser 443:237-247. https://doi.org/10.3354/meps09427 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 443. Online publication date: December 20, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Inter-nesting habitat-use patterns of loggerhead sea turtles: enhancing satellite tracking with benthic mapping

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 11:77-90 (2010) - DOI: https://doi.org/10.3354/ab00296 Inter-nesting habitat-use patterns of loggerhead sea turtles: enhancing satellite tracking with benthic mapping Kristen M. Hart1,*, David G. Zawada2, Ikuko Fujisaki3, Barbara H. Lidz2 1US Geological Survey, Southeast Ecological Science Center, Davie, Florida 33314, USA 2US Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida 33701, USA 3University of Florida, Ft. Lauderdale Research and Education Center, Davie, Florida 33314, USA *Email: kristen_hart@usgs.gov ABSTRACT: The loggerhead sea turtle Caretta caretta faces declining nest numbers and bycatches from commercial longline fishing in the southeastern USA. Understanding spatial and temporal habitat-use patterns of these turtles, especially reproductive females in the neritic zone, is critical for guiding management decisions. To assess marine turtle habitat use within the Dry Tortugas National Park (DRTO), we used satellite telemetry to identify core-use areas for 7 loggerhead females inter-nesting and tracked in 2008 and 2009. This effort represents the first tracking of DRTO loggerheads, a distinct subpopulation that is 1 of 7 recently proposed for upgrading from threatened to endangered under the US Endangered Species Act. We also used a rapid, high-resolution, digital imaging system to map benthic habitats in turtle core-use areas (i.e. 50% kernel density zones). Loggerhead females were seasonal residents of DRTO for 19 to 51 d, and individual inter-nesting habitats were located within 1.9 km (2008) and 2.3 km (2009) of the nesting beach and tagging site. The core area common to all tagged turtles was 4.2 km2 in size and spanned a depth range of 7.6 to 11.5 m. Mapping results revealed the diversity and distributions of benthic cover available in the core-use area, as well as a heavily used corridor to/from the nesting beach. This combined tagging-mapping approach shows potential for planning and improving the effectiveness of marine protected areas and for developing spatially explicit conservation plans. KEY WORDS: Dry Tortugas · Caretta caretta · Marine protected area · MPA · Marine spatial planning · Satellite telemetry · Benthic cover · Habitat mapping · Fixed-kernel density estimator Full text in pdf format PreviousNextCite this article as: Hart KM, Zawada DG, Fujisaki I, Lidz BH (2010) Inter-nesting habitat-use patterns of loggerhead sea turtles: enhancing satellite tracking with benthic mapping. Aquat Biol 11:77-90. https://doi.org/10.3354/ab00296Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 11, No. 1. Online publication date: November 16, 2010 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2010 Inter-Research.

Identification of high-use internesting habitats for eastern Pacific leatherback turtles: role of the environment and implications for conservation

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 10:215-232 (2010) - DOI: https://doi.org/10.3354/esr00251 Identification of high-use internesting habitats for eastern Pacific leatherback turtles: role of the environment and implications for conservation George L. Shillinger1,*, Alan M. Swithenbank1, Steven J. Bograd2, Helen Bailey2, Michael R. Castelton1, Bryan P. Wallace3, James R. Spotila4, Frank V. Paladino5, Rotney Piedra6, Barbara A. Block1 1Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA 2NOAA/NMFS/SWFSC/Environmental Research Division, Pacific Grove, California 93950, USA 3Center for Applied Biodiversity Science, Conservation International, Arlington, Virginia 22202, USA 4Department of Bioscience and Biotechnology, Drexel University, Philadelphia, Pennsylvania 19104, USA 5Department of Biology, Indiana University-Purdue University, Fort Wayne, Indiana 46805, USA 6Parque Nacional Marino Las Baulas, Ministerio de Ambiente y Energía, Apartado 10104-1000, San José, Costa Rica *Email: georges@stanford.edu ABSTRACT: The numbers of leatherback turtles Dermochelys coriacea in the eastern Pacific Ocean have declined by up to 90% in the past 2 decades. Initially, egg harvesting was determined to be the largest causative factor, but now that this has been eliminated, high estimated adult mortality from fisheries bycatch poses the single greatest threat to this population. During the nesting season, adult female leatherback turtles nest multiple times and occupy coastal marine habitats near their nesting beaches. In this study, we characterize the interannual variability of high-use internesting habitats used by 44 (out of 46 total) female leatherback turtles that were satellite-tagged at Playa Grande, Costa Rica, from 2004 to 2007. A total of 1135 d of internesting movements were recorded across 3 tracking years. The core 25% utilization distribution (UD) remained predominantly centered within the marine protected area, Parque Nacional Marino Las Baulas (PNMB). The turtles generally dispersed in a northward or southward direction over the shallow continental shelf framing Costa Rica’s Nicoya Peninsula. However, there was considerable interannual variation in the shape and area of the larger UD polygons, which was driven by variability in the thermal environment. The maximum swimming speeds and distance traveled from the nesting beach occurred during 2007. Significantly deeper and longer dive durations to cooler temperatures also occurred in this year, which may have been in response to the warming trend from the south driven by the strong Costa Rica Coastal Current. Our findings, therefore, validate the importance of PNMB as a critical habitat for internesting leatherback turtles, but also suggest that a latitudinal expansion of the park is warranted. KEY WORDS: Conservation · Costa Rica · Dermochelys coriacea · Diving behavior · Marine Spatial Planning · Marine turtles · Satellite tracking Full text in pdf format PreviousNextCite this article as: Shillinger GL, Swithenbank AM, Bograd SJ, Bailey H and others (2010) Identification of high-use internesting habitats for eastern Pacific leatherback turtles: role of the environment and implications for conservation. Endang Species Res 10:215-232. https://doi.org/10.3354/esr00251Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 10. Online publication date: February 02, 2010 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2010 Inter-Research.

Incorporating marine turtle habitats into the marine protected area design for the Great Barrier Reef Marine Park, Queensland, Australia

Marine turtle habitats were considered in the design of the new zoning network for the Great Barrier Reef Marine Park as part of the Representative Areas Programme. One of the specific design guidelines developed was the incorporation of marine turtle inter-nesting and foraging habitats into the overall network of no-take areas. The guideline was refined further for individual nesting and foraging sites to incorporate all very high priority nesting sites and to incorporate 20% of each identified foraging site, respectively. Marine turtle inter-nesting habitat increased in no-take area protection from 781 km2 to 1 886 km2 (23.4% to 56.5% of all identified sites); marine turtle foraging habitat increased in no-take area protection from 3 063 km2 to 12 490 km2 (7.1% to 29.1% of all identified sites). Although the nesting and foraging principles were not achieved in total for all identified marine turtle sites, overall the level of protection afforded by the Great Barrier Reef Marine Park Zoning Plan 2003 increased for nearly all marine turtle sites identified. Additionally, other activities (e.g. water quality, fisheries, traditional use of marine resources) occurring in the Great Barrier Reef Marine Park that may impact upon marine turtles are being addressed via other mechanisms.

Reproductive Homing and Internesting Behavior of the Green Turtle (Chelonia mydas) at Ascension Island, South Atlantic Ocean

Female green turtles (Chelonia mydas) were tagged while nesting on the 32 cove-head beaches distributed in four clusters along the leeward shoreline of Ascension Island. The turtles showed high nesting site fidelity, returning to the same beach cluster during at least 70% of consecutive observed renesting emergences. Stronger site fidelity to beach clusters and also to points within the boundaries of a beach was more evident in emergences separated by less than 7 d (assumed to be repeated attempts to lay one clutch of eggs) than in nestings separated by longer time intervals, involving separate egg clutches. These differences correlate with predictable patterns of behavior observed in females, the movements of which were visually tracked during their internesting intervals. After successful oviposition, most of the tracked females traveled to a shallow area off the northwest coast of the island. Those that did not lay eggs remained in the vicinity of the beach just abandoned, traveling back and forth in nearshore waters until daylight when they moved into deeper water. The rates, patterns and periodicities of travel by Ascension turtles in their internesting habitat after successful and aborted nestings are compared with those of internesting female turtles at other breeding grounds; possible explanations for observed differences are discussed.