Fossette S.,University of Strasbourg |
Fossette S.,French National Center for Scientific Research |
Fossette S.,University of Swansea |
Girard C.,University of Strasbourg |
And 13 more authors.
Background: Sea turtles are long-distance migrants with considerable behavioural plasticity in terms of migratory patterns, habitat use and foraging sites within and among populations. However, for the most widely migrating turtle, the leatherback turtle Dermochelys coriacea, studies combining data from individuals of different populations are uncommon. Such studies are however critical to better understand intra- and inter-population variability and take it into account in the implementation of conservation strategies of this critically endangered species. Here, we investigated the movements and diving behaviour of 16 Atlantic leatherback turtles from three different nesting sites and one foraging site during their post-breeding migration to assess the potential determinants of intra- and inter-population variability in migratory patterns. Methodology/Principal Findings: Using satellite-derived behavioural and oceanographic data, we show that turtles used Temporary Residence Areas (TRAs) distributed all around the Atlantic Ocean: 9 in the neritic domain and 13 in the oceanic domain. These TRAs did not share a common oceanographic determinant but on the contrary were associated with mesoscale surface oceanographic features of different types (i.e., altimetric features and/or surface chlorophyll a concentration). Conversely, turtles exhibited relatively similar horizontal and vertical behaviours when in TRAs (i.e., slow swimming velocity/sinuous path/shallow dives) suggesting foraging activity in these productive regions. Migratory paths and TRAs distribution showed interesting similarities with the trajectories of passive satellite-tracked drifters, suggesting that the general dispersion pattern of adults from the nesting sites may reflect the extent of passive dispersion initially experienced by hatchlings. Conclusions/Significance: Intra- and inter-population behavioural variability may therefore be linked with initial hatchling drift scenarios and be highly influenced by environmental conditions. This high degree of behavioural plasticity in Atlantic leatherback turtles makes species-targeted conservation strategies challenging and stresses the need for a larger dataset (>100 individuals) for providing general recommendations in terms of conservation. © 2010 Fossette et al. Source
Esteban N.,University of Swansea |
van Dam R.P.,Chelonia Inc. |
Harrison E.,Sea Turtle Conservancy |
Herrera A.,University of Exeter |
Berkel J.,Statia National Marine Park
Satellite transmitters were deployed on three green turtles, Chelonia mydas, and two hawksbill turtles, Eretmochelys imbricata, nesting in the Lesser Antilles islands, Caribbean, between 2005 and 2007 to obtain preliminary information about the inter-nesting, migratory and foraging habitats in the region. Despite the extremely small dataset, both year-round residents and migrants were identified; specifically, (1) two green turtles used local shallow coastal sites within 50 km of the nesting beach during all of their inter-nesting periods and then settled at these sites on completion of their breeding seasons, (2) one hawksbill turtle travelled 200 km westward before reversing direction and settling within 50 km of the original nesting beach and (3) one green and one hawksbill turtle initially nested at the proximate site, before permanently relocating to an alternative nesting site over 190 km distant. A lack of nesting beach fidelity was supported by flipper tag datasets for the region. Tagging datasets from 2002 to 2012 supported that some green and hawksbill individuals exhibit low fidelity to nesting beaches, whereas other females exhibited a high degree of fidelity (26 turtles tagged, 40.0 km maximum distance recorded from original nesting beach). Individual turtles nesting on St Eustatius and St Maarten appear to exhibit behavioural plasticity in their inter-nesting behaviour and post-nesting migration routes in the eastern Caribbean. The tracking and tagging data combined indicate that some of the green and hawksbill females that nest in the Lesser Antilles islands are year-round residents, whilst others may nest and forage at alternative sites. Thus, continued year-round protection of these islands and implementation of protection programmes in nearby islands could contribute towards safeguarding the green and hawksbill populations of the region. © 2015, Springer-Verlag Berlin Heidelberg. Source
Crawled News Article
Researchers created a special lighting that can illuminate fishing nets. The add-on can help sea turtles avoid capture and lower the instance of fishermen accidentally catching them. The team from the University of Exeter believed that the green light emitting diodes (LEDs) can help sea turtles spot the mesh netting and avoid it without disturbing the fish. They tested their prototype off the Peru coast in a controlled experiment. The fishing nets not fitted with LEDs had 125 green turtles caught in the netting while the lit one only had 62. The numbers of guitarfish caught by the two nets were not affected by the illuminating add-ons. Each LED light cost about £1.40 ($2). With the illuminating fishing net, the research demonstrated that saving one turtle cost only £24 ($34). This amount can still be reduced if the technology will be used on a much larger scale. "This is very exciting because it is an example of something that can work in a small-scale fishery which for a number of reasons can be very difficult to work with," said Darwin Initiative research fellow Jeffrey Mangel. Mangel added that the sea turtle's eastern Pacific populations are one of the most vulnerable in the world. Lowering the sea turtle's bycatch could help in managing and recovering its population in the region. When the turtles get caught in the fishing nets or lines, it prevents them from reaching the surface for air and end up drowning. According to the Sea Turtle Conservancy, more than 250,000 sea turtles are captured, injured or killed accidentally by fishermen in the U.S. The baits often attract the sea turtles that they end up getting caught on the hooks used in catching fish. "Bycatch is a complex, global issue that threatens the sustainability and resilience of our fishing communities, economies and ocean ecosystems," said assistant NOAA administrator for fisheries, Eileen Sobeck. The experiment was published in the Marine Ecology Progress Series journal and conducted in northern Peru's Sechura Bay. The study was supported by the National Oceanic and Atmospheric Administration, the Lima-based not-for-profit organization ProDelphinus and the Darwin Initiative by the UK Government.
Ceriani S.A.,Florida Fish And Wildlife Conservation Commission |
Ceriani S.A.,University of Central Florida |
Roth J.D.,University of Manitoba |
Tucker A.D.,Mote Marine Laboratory |
And 5 more authors.
Migratory animals spend different periods of their lives in widely separated and ecologically different locations; their experiences from one activity/period/site (e.g., foraging) can dramatically affect their success during another (e.g., breeding). Carry-over effects reflect the influence of foraging quality on reproductive behaviors of migratory species, such as nesting loggerhead sea turtle (Caretta caretta), which vary greatly in body size and reproductive parameters. We investigated carry-over effects on 330 loggerheads nesting at the Archie Carr National Wildlife Refuge (Melbourne Beach, Florida), one of the largest aggregations in the Western Hemisphere, using telemetry, stable isotope analysis and reproductive parameters. We assigned foraging locations used during the non-breeding period with discriminant function analysis and determined the relative contributions to different foraging regions from 2007 to 2012. Foraging regions significantly influenced female body size and fecundity. Loggerheads foraging southeast of the nesting beach in the vicinity of the Bahamas and Florida Keys laid larger clutches and had a shorter breeding frequency. On average, 47 % (±3 % SE) of the females foraged year-round in this area, while 33 % (±4 % SE) resided on the Southwest Florida continental shelf south of Tampa Bay and 18 % (±2 % SE) undertook seasonal migrations and foraged north of Cape Hatteras, North Carolina. Relative contributions to the foraging areas did not change over the 6-year period. The northern foraging area consistently contributed the fewest females despite being the most productive oceanographic region suggesting a trade-off between foraging area productivity and distance to the nesting beach. We reaffirm that the isotopic approach can be used to interpret trends in abundance at nesting beaches and demographic parameters affecting those trends. Understanding geospatial linkages and relative importance of foraging areas is critical to fostering appropriate management and conservation strategies for migratory species. © 2015, Springer-Verlag Berlin Heidelberg (outside the USA). Source
Ceriani S.A.,Florida Fish And Wildlife Conservation Commission |
Roth J.D.,University of Manitoba |
Sasso C.R.,National Oceanic and Atmospheric Administration |
McClellan C.M.,University of Exeter |
And 10 more authors.
Stable isotope analysis can be used to infer geospatial linkages of highly migratory species. Identifying foraging grounds of marine organisms from their isotopic signatures is becoming de rigueur as it has been with terrestrial organisms. Sea turtles are being increasingly studied using a combination of satellite telemetry and stable isotope analysis; these studies along with those from other charismatic, highly vagile, and widely distributed species (e.g., tuna, billfish, sharks, dolphins, whales) have the potential to yield large datasets to develop methodologies to decipher migratory pathways in the marine realm. We collected tissue samples (epidermis and red blood cells) for carbon (δ13C) and nitrogen ((δ15N) stable isotope analysis from 214 individual loggerheads (Caretta caretta) in the Northwest Atlantic Ocean (NWA). We used discriminant function analysis (DFA) to examine how well δ13C and (δ15N classify loggerhead foraging areas. The DFA model was derived from isotopic signatures of 58 loggerheads equipped with satellite tags to identify foraging locations. We assessed model accuracy with the remaining 156 untracked loggerheads that were captured at their foraging locations. The DFA model correctly identified the foraging ground of 93.0% of individuals with a probability greater than 66.7%. The results of the external validation (1) confirm that assignment models based on tracked loggerheads in the NWA are robust and (2) provide the first independent evidence supporting the use of these models for migratory marine organisms. Additionally, we used these data to generate loggerhead-specific δ13C and (δ15N isoscapes, the first for a predator in the Atlantic Ocean. We found a latitudinal trend of δ13C values with higher values in the southern region (20-25°N) and a more complex pattern with (δ15N, with intermediate latitudes (30-35°N) near large coastal estuaries having higher (δ15N-enrichment. These results indicate that this method with further refinement may provide a viable, more spatially-explicit option for identifying loggerhead foraging grounds. Copyright: © 2014 Ceriani et al. Source