ABSTRACT.Hawksbill sea turtles (Eretmochelys imbricata) inhabiting the eastern Pacific Ocean are one of the world's most threatened marine turtle management units. Despite the fact that knowledge about the status of sea turtles at foraging grounds is a key element for developing the effective conservation strategies, comprehensive studies of hawksbills at foraging habitats in the eastern Pacific remain lacking. For many years anecdotal information indicated Coiba Island National Park in Panama as a potentially important hawksbill foraging ground, which led to the initiation of monitoring surveys in September 2014. Ongoing mark-recapture surveys to assess population status, generate demographic data and identify key foraging sites have been conducted every six months in the park since that time. To date, a total of six monitoring campaigns consisting of four days each have been conducted, leading to the capture and tagging of 186 hawksbills, 51 of which were recaptured at least once. The size range of captured individuals was 30.0 to 75.5 cm and largely comprised of juveniles. Somatic growth rates of individual hawksbills were highly variable, ranging from -0.78 to 7.1 cm year -1 . To our knowledge, these are the first published growth rates for juvenile hawksbill turtles in the eastern Pacific Ocean. When these growth data are combined with information on hawksbill demography and distribution, our findings indicate Coiba Island National Park is one of the most important known foraging sites for hawksbill sea turtles in the eastern Pacific Ocean.

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The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

www.nature.com/scientificreports enhanced, coordinated conservation efforts required to avoid extinction of critically endangered Eastern Pacific leatherback turtles the Laúd opo network † Failure to improve the conservation status of endangered species is often related to inadequate allocation of conservation resources to highest priority issues. Eastern Pacific (EP) leatherbacks are perhaps the most endangered sea turtle population in the world, and continue on a path to regional extinction. To provide coherent, regional conservation targets, we developed a population viability analysis and examined hypothetical scenarios describing effects of conservation activities that either reduced mortality or increased production of hatchlings (or both). Under status quo conditions, EP leatherbacks will be extirpated in <60 yr. To ensure a positive, long-term population trajectory, conservation efforts must increase adult survivorship (i.e., reduce adult mortality) by ≥20%, largely through reduction of fisheries bycatch mortality. Positive trajectories can be accelerated by increased production of hatchlings through enhanced nest protection and treatment. We estimate that these efforts must save approximately 200-260 adult and subadult leatherbacks and produce approximately 7,000-8,000 more hatchlings annually. Critically, reductions in late-stage mortality must begin within 5 years and reach 20% overall within the next 10-15 years to ensure population stabilization and eventual increase. These outcomes require expanded, sustained, coordinated, high-priority efforts among several entities working at multiple scales. Fortunately, such efforts are underway.Species declines driven by human causes have been well-documented across taxonomic groups in recent decades 1 . In some cases, persistent, effective conservation efforts -often coupled with enforced legal protections -have stabilized and even begun to recover populations 2 . Among long-lived marine species such as marine mammals, turtles, birds, and elasmobranchs, there is wide variation in long-term population trends and whether conservation efforts have successfully achieved recovery goals 3-5 . For populations to recover, threats must be reduced to levels that first stabilize, then increase population abundance; however, failure to recover depleted populations often is related to insufficient (i.e., too little for too short a time period) or inefficient allocation of limited resources to conservation actions of highest potential benefit to the target population 6 .Marine turtles exemplify these issues, given their global distributions and varied conservation status among regional population segments (i.e., regional management units, RMUs; Ref. 7 ). Many RMUs within and among the seven extant marine turtle species are depleted relative to historical abundance because of human-caused mortality, namely direct harvest of turtles and their eggs and incidental capture in fisheries 8 . However, some marine turtle populations are showing signs of recovery following conservati...