When do leatherback sea turtles migrate

Data are transmitted or can be downloaded on a daily basis. The data has revealed that the turtles initially spent considerable amount of time around the nesting site. Initial results show and swimming directly southwards in the Indian Ocean.

Turtle swam approximately km and is currently south of Sumatra near the Cocos Keeling Islands, and appears to be swimming towards Australia. The leatherback turtle nesting beaches in the Andaman and Nicobar are comparatively better protected due to their remoteness. Depredation of eggs by monitor lizards, feral dogs and pigs are threats on land, while interaction with fisheries seems to be the important threat at sea. Poor coastal management may also lead to the loss of habitats through erosion.

In addition, the impact of climate change on coastal habitats as well as directly on sea turtle populations through the effect on sex ratios, has not yet been fully understood. Ongoing studies using genetics and telemetry will provide insights into the biology of these animals which will help in their conservation. You must be logged in to post a comment. Search Conservation India. Turn off, shield, or redirect lights visible from the beach—lights disorient hatchlings and discourage nesting females from coming onto beaches to lay their eggs.

After a day at the beach, remove recreational beach equipment like chairs and umbrellas so sea turtles are not entrapped or turned away. Also, fill in holes and knock down sandcastles before you leave—they can become obstacles for nesting turtles or emerging hatchlings.

Do not drive on sea turtle nesting beaches —vehicles can deter females from nesting, directly strike hatchlings and nesting turtles, damage incubating nests, and create ruts that prevent hatchlings from reaching the sea. If you see a stranded, injured, or entangled sea turtle, contact professional responders and scientists who can take appropriate action.

Numerous organizations around the country are trained and ready to respond. Learn who you should contact when you encounter a stranded or injured marine animal. This initiative is a concerted, agency-wide effort launched in to spotlight and save the most highly at-risk marine species. Pacific leatherback sea turtles are genetically and biologically unique. Pacific leatherback populations have plummeted in recent decades—Western Pacific leatherbacks have declined more than 80 percent and Eastern Pacific leatherbacks have declined by more than 97 percent.

Extensive turtle and egg harvest and bycatch in fishing gear are the primary causes of these declines. Leatherbacks are listed as endangered under the Endangered Species Act. The Pacific leatherback continues to decline. The dire status for Pacific leatherbacks make them a priority for recovery and conservation efforts within NOAA Fisheries and with our partners worldwide to stabilize and prevent extinction of this iconic species.

Pacific leatherbacks are split into two populations—Western Pacific and Eastern Pacific—based on range distribution and biological and genetic characteristics. Western Pacific leatherbacks nest in the Indo-Pacific region and migrate to the tropical waters of the Indonesian seas, the South China Sea, Malaysia, the Philippines, and throughout the temperate waters of the North Pacific, including areas of open ocean in the central North Pacific and coastal areas off the west coast of the United States, as well as to southeastern Australia and New Zealand.

Eastern Pacific leatherbacks nest along the Pacific coast of Mexico and Costa Rica and migrate south to foraging grounds off South America. Pacific leatherbacks are considered one of the most at-risk species because of the drastic decreasing trend since the s.

Western Pacific leatherbacks have declined more than 80 percent and Eastern Pacific leatherbacks have declined by more than 97 percent. More recent trend analyses, on the primary nesting beaches in both the East and West Pacific, continue to show declines.

Leatherbacks are pelagic open ocean animals, but they also feed in and migrate through coastal waters. Western Pacific leatherbacks engage in one of the greatest migrations of any air-breathing marine animal, swimming from tropical nesting beaches in the western Pacific primarily Indonesia, Papua New Guinea, and the Solomon Islands to foraging grounds in the eastern North Pacific off the U.

The nearly 7,mile trans-Pacific journey through the exclusive economic zones of multiple Pacific nations and international waters requires 10 to 12 months to complete. In , critical habitat was designated off of the U. West Coast California, Oregon, and Washington , because these areas are key foraging sites for the Western Pacific leatherback.

Adult females require sandy nesting beaches in warm, tropical climates for egg laying. Western Pacific leatherbacks demonstrate a bimodal pattern of seasonal nesting during the winter and summer months in the west Pacific, primarily in Indonesia, Papua New Guinea, and the Solomon Islands. Like other sea turtle species, leatherbacks face significant threats from bycatch in fisheries e.

Leatherbacks are particularly vulnerable to bycatch in fishing gear. Gear modification and best practices have been implemented in many fisheries that have reduced incidental bycatch of leatherbacks, but globally, impacts from artisanal and industrial fishing operations have not been resolved.

The United States has taken significant steps to protect leatherbacks in our waters. In the Pacific, a leatherback conservation area was established off the coast of California in that prohibits drift gillnet fishing from August 15 to November 15 in , square miles of the Exclusive Economic Zone.

In , the Marianas Trench, Rose Atoll, and Pacific Remote Islands marine national monuments were established, prohibiting commercial and recreational fisheries, thus providing important protected areas for sea turtles in this region. And similar to Atlantic fisheries, Hawaii-based longline fisheries have been regulated to reduce leatherback interactions.

Additionally, vessel owners and captains participating in the Hawaii-based longline fishery and the California drift gillnet fishery must attend Protected Species Workshops annually where they receive new and updated information on sea turtles in the Pacific Ocean and new, relevant fisheries regulations, as well as training on safe handling and release procedures including the resuscitation of sea turtles.

Longline fishermen are also required to carry and use dip nets, line cutters, and de-hookers to release any incidentally-caught sea turtles. While significant conservation activities continue in the United States, the highly migratory nature of Pacific leatherbacks necessitates regular cooperation with international partners to address the main threats.

International collaboration includes participation in several multilateral and regional treaties that have resulted in measures to conserve leatherback populations. Some of the accomplishments under these agreements include the development of the Inter-American Convention for the Protection and Conservation of Sea Turtles East Pacific Leatherback Task Force, which has identified measures to reduce mortality of Eastern Pacific leatherbacks in marine habitats and protect nesting sites and nesting females to increase reproductive productivity.

Fish and Wildlife Service support bilateral projects through grants and in-kind support to recover Pacific leatherbacks throughout their range. FWS have collaborated with local institutions, like The State University of Papua UNIPA , for more than a decade to reduce poaching on nesting beaches, establish regular nesting surveys, improve community engagement in the protection of the nesting beaches, and ensure that protection continues into the future.

FWS also work bilaterally with several countries to reduce leatherback bycatch in coastal waters, particularly in the Pacific. As part of our Species in the Spotlight initiative, NOAA Fisheries developed a Priority Action Plan for the Pacific leatherback , which builds on the Priority Action Plan and details the key conservation efforts that are needed to recover this critically endangered species.

Without focused efforts in the Pacific, leatherbacks may not recover and may become eliminated from the entire ocean basin. They established a science-based management plan that minimizes sea turtle nest failure and enhances hatchling production. Leatherback turtles are protected under the Endangered Species Act and listed as endangered. This means that the leatherback turtle is in danger of extinction throughout all or a significant portion of its range.

NOAA Fisheries is working to protect and recover this species in many ways, with the goal of conserving and recovering the species worldwide. FWS having the lead on the nesting beaches. Both federal agencies, along with many state and U. FWS to develop and implement recovery plans which provide a blueprint for conservation of the species and measurable criteria to gauge progress toward recovery. The major recovery actions for leatherback turtles include:.

Two recovery plans have been developed to recover and protect leatherback turtle populations found in U. Each is focused on the unique needs of leatherback turtles in the various regions. The highly migratory behavior of sea turtles makes them shared resources among many nations, so conservation efforts for sea turtle populations must extend beyond national boundaries. This necessitates international collaboration and coordination.

Learn more about international conservation efforts below. NOAA Fisheries is working to minimize effects from human activities that are detrimental to the recovery of leatherback turtles in the United States and internationally. Together with our partners, we undertake numerous activities to support the goals of the leatherback turtle recovery plans, with the ultimate goal of species recovery.

Efforts to conserve leatherback turtles include:. Those areas may be designated as critical habitat through a rulemaking process.

A critical habitat designation does not set up a marine preserve or refuge. Rather, federal agencies that undertake, fund, or permit activities that may affect designated critical habitat areas are required to consult with NOAA Fisheries to ensure that their actions do not adversely modify or destroy these designated critical habitats. FWS designated critical habitat for endangered leatherback turtles for coastal waters adjacent to Sandy Point in St.

Croix, U. View the leatherback turtle critical habitat map for the U. In our study, our conservation target is clear: the survival of migrating adult female loggerheads. In the Loggerhead Recovery Plan, managing migratory pathways and minimizing vessel strike mortality are listed as Recovery Objectives NMFS and USFWS, , and therefore our results directly provide scientific information needed for designing management strategies for this threatened species.

In order to inform what threshold is acceptable for each threat, a future CEA would benefit from an understanding of what mortality level during migration is deemed sustainable for population recovery. As new information becomes available on the spatial intensity of threats, this estimated corridor can be used to inform adaptive management of threats during the migratory period.

Overall, it is imperative to understand migration patterns and threats for these highly mobile species, and our conservative estimate of threats provides valuable information for the management and recovery of loggerhead sea turtles. The datasets generated for this study will not be made publicly available.

Restrictions apply to the datasets. Raw data is exempt from publication due to the sensitivity of endangered species location information. Requests to access the datasets should be directed to the corresponding author.

All other data used for analyses are presented in the manuscript. AI and KH contributed to the conception and design of the study. KH acquired funding. KH and ML managed tag deployment and data collection. AI wrote the first draft of the manuscript.

All authors contributed to manuscript revision, read and approved the submitted version. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

We acknowledge assistance from D. Ingram, J. Isaacs, A. Lauritsen, S. MacPherson, and J. Phillips from the U. Reynolds for field assistance in Alabama. We also thank many U. Geological Survey volunteers and employees for assistance in the field. We acknowledge the use of the satellite-tracking and analysis tool STAT and telemetry data generated as part of the Deepwater Horizon Natural Resource Damage Assessment publicly available from www.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U. Alerstam, T. Long-distance migration: evolution and determinants. Oikos 2, — Almpanidou, V. Thermal heterogeneity along the migration corridors of sea turtles: implications for climate change ecology.

Marine Biol. Berger, J. Connecting the dots: an invariant migration corridor links the Holocene to the present. Block, B. Tracking apex marine predator movements in a dynamic ocean. Nature , 86— Breed, G. Sex-specific, seasonal foraging tactics of adult grey seals Halichoerus grypus revealed bystate-space analysis. Ecology 90, — Casale, P. Sea turtle strandings reveal high anthropogenic mortality in Italian waters. CLS Google Scholar. Costello, M. A census of marine biodiversity knowledge, resources, and future challenges.

PLoS One 5:e Dingle, H. Oxford: Oxford University Press. Donlan, C. Using expert opinion surveys to rank threats to endangered species: a case study with sea turtles.

Endres, C. Multi-modal homing in sea turtles: modeling dual use of geomagnetic and chemical cues in island-finding. ESRI Foley, A. Postnesting migratory behavior of loggerhead sea turtles Caretta caretta from three Florida rookeries. Species Res. Girard, C. Post-nesting migrations of loggerhead sea turtles in the Gulf of Mexico: dispersal in highly dynamic conditions. Hart, K. Marine threats overlap key foraging habitat for two imperiled sea turtle species in the Gulf of Mexico.

Sympatry or syntopy? Investigating drivers of distribution and co-occurrence for two imperiled sea turtle species in Gulf of Mexico neritic waters. Common coastal foraging areas for loggerheads in the Gulf of Mexico: opportunities for marine conservation. Migration, foraging, and residency patterns for northern gulf loggerheads: implications of local threats and international movements.

PLoS One 9:e Movements and habitat-use of loggerhead sea turtles in the northern Gulf of Mexico during the reproductive period. PLoS One 8:e Biotelemetry 3, 1— Hays, G. Satellite telemetry suggests high levels of fishing-induced mortality in marine turtles. Global patterns for upper ceilings on migration distance in sea turtles and comparisons with fish, birds and mammals. Henkel, J. The state-space model also estimates the behavioral mode of the turtle as either foraging or transiting e. The last dates of foraging were consistent with migration dates estimated from speed and diving behavior James, Ottensmeyer, et al.

We inferred foraging prior to migration in tracking data see supplementary movie from 27 turtles. Five turtles were tracked through 2 northern foraging seasons and 6 records were censored before migration departure was observed, resulting in a data set of 32 foraging seasons and 26 migration departures.

Fourteen satellite tags provided direct measures of SST. Because the state-space estimates do not correspond directly to the time that the tag recorded SST, the median SST for observations within the 6-h period was used. Depths were interpolated from the S bathymetry grid, a combination of Smith and Sandwell and General Bathymetric Charts of the Oceans data of Marks and Smith The average chlorophyll-a concentrations within 3 days and 0.

Because oceanographic conditions may be transient, we also calculated a lagged average of the temperatures and chlorophyll concentrations experienced by the turtle for the previous week.

Tracks from satellite-tagged animals are often cut short unexpectedly e. Ignoring or making arbitrary assumptions about these censored individuals is inappropriate Castro-Santos and Haro Cox's proportional hazards model, a technique for the study of mortality and mechanical failure, is effective for the analysis of censored data Cox As this method also allows time-dependent covariates e. The concept of hazard, the probability of an event given that it has not yet happened, is useful in modeling events that can only happen once e.

In this case, the hazard corresponds to the departure rate, which is the chance of a turtle leaving on its southward migration given that it has not already left.

Variables were added and removed by stepwise selection using the Akaike's information criterion AIC as implemented in R version 2. Standard errors were estimated based on jackknife estimates of the variance leaving out individual turtles. The sensitivity of the analysis was investigated by in turn lowering the foraging threshold of the behavioral estimates of the state-space model, weighting the Cox model by the inverse of the total of the estimated variances of the latitude and longitude estimates and decimating the data by a factor of 2, 4, and 8.

Location and behavior estimates were available for 6-h periods prior to migration. One-week lagged temperature averages were obtained for observations, and lagged chlorophyll averages were obtained for observations. The final departure model selected by AIC included latitude, longitude, longitude 2 , 1-week lagged SST, 1-week lagged average chlorophyll, and the interaction of 1-week lagged average chlorophyll with latitude see Table 1.

Other variables did not improve the model as measured by AIC and were excluded from the analysis. The estimated effects were not qualitatively different after varying the threshold for inferred foraging, weighting the data by the uncertainty in the estimated positions or decimating the data.

Given these observations, Cox's model appears suitable for the study of migration cues. Results from stepwise Cox's proportional hazards modeling of the onset of migration in leatherback turtles tagged off Nova Scotia. Temperature and chlorophyll are the average of the SSTs and chlorophyll-a concentrations experienced by the turtle the prior week.

The mean and range of the variables for all observations 6-h periods of the study are shown for comparison. The location of the turtle had a significant relationship with departure rate. Leatherback departure rate increased with latitude with the effect becoming stronger in waters with higher chlorophyll concentrations. Although departure rate increased consistently with latitude, the effects of longitude exhibited a minimum departure rate at Contour plot of the relative departure rates for turtles foraging in northern waters as predicted by Cox's proportional hazards model.

Red indicates the lowest departure rates and yellow the highest. Contour lines indicate a fold increase in departure rate from the line below them. Gray circles indicate turtle positions, and black circles indicate departures.

Chlorophyll and SST were set at mean values Inset shows locations discussed in the paper. Inset dotted gray lines follows the m depth contour. Environmental conditions were also related to departure rate. Departure rate was not significantly affected by 1-week lagged average chlorophyll concentration in the central latitudes At latitudes greater than The effect of chlorophyll strengthened with latitude up to a In addition to estimating the proportional change in chance of departure, Cox's proportional hazards model can also estimate the baseline departure rates at the means of all variables.

The probability of turtle departure is characterized by a preliminary period with little chance of departure followed by a rapid increase of departure probability to almost certain departure Figure 2. Predicted proportion of leatherbacks that have initiated their southward migration at mean latitude, longitude, and 1-week lagged average temperature and chlorophyll for the study.

If the turtles in this study are assumed to be random samples of the populations in these areas and their departure rates are not affected by tagging, population-level migration departure patterns can be inferred from these departure rates.

One-week lagged average chlorophyll and SST were held steady at their mean value for the data set Leatherback departure rate was significantly related to the position of the turtle. Compensation for distance traveled could explain earlier departures from foraging areas further from southern nesting and wintering grounds. Animals foraging in more distant areas would be expected to depart earlier. For example, in black-tailed godwit Limosa limosa , the distance between foraging and breeding areas does not predict arrival date Gunnarsson et al.

Based on a mean swim speed for internesting leatherbacks of 0. Moreover, faster minimum speeds based on telemetry appear common in migrating turtles James, Myers, and Ottensmeyer