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Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long‐lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio‐temporal effects on hawksbill growth dynamics over a 33‐yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio‐temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region‐wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0‐ or 1‐yr lags: positive with the Multivariate El Niño Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs.

International audience; In 2010, an international group of 35 sea turtle researchers refined an initial list of more than 200 research questions into 20 metaquestions that were considered key for management and conservation of sea turtles. These were classified under 5 categories: reproductive biology, biogeography, population ecology, threats and conservation strategies. To obtain a picture of how research is being focused towards these key questions, we undertook a systematic review of the peer-reviewed literature (2014 and 2015) attributing papers to the original 20 questions. In total, we reviewed 605 articles in full and from these 355 (59%) were judged to substantively address the 20 key questions, with others focusing on basic science and monitoring. Progress to answering the 20 questions was not uniform, and there were biases regarding focal turtle species, geographic scope and publication outlet. Whilst it offers some meaningful indications as to effort, quantifying peer-reviewed literature output is obviously not the only, and possibly not the best, metric for understanding progress towards informing key conservation and management goals. Along with the literature review, an international group based on the original project consortium was assigned to critically summarise recent progress towards answering each of the 20 questions. We found that significant research is being expended towards global priorities for management and conservation of sea turtles. Although highly variable, there has been significant progress in all the key questions identified in 2010. Undertaking this critical review has highlighted that it may be timely to undertake one or more new prioritizing exercises. For this to have maximal benefit we make a range of recommendations for its execution. These include a far greater engagement with social sciences, widening the pool of contributors and focussing the questions, perhaps disaggregating ecology and conservation.

We tracked two adult female green turtles (Chelonia mydas) from their nesting location on Masirah Island, Oman (lat 20.441°N, long 58.843°E) into the Red Sea. Comparing these tracks with published movements of nesting loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) turtles, also tracked from Masirah, revealed remarkably different inter-specific patterns of post-nesting dispersal. High-capacity artisanal fisheries, with undescribed levels of sea turtle bycatch, exist within the region, making introduction of effective conservation measures difficult.

Much is still to be learned about the spatial ecology of foraging marine turtles, especially for juveniles and adult males which have received comparatively little attention. Additionally, there is a paucity of ecological information on growth rates, size and age at maturity, and sex ratios at different life stages; data vital for successful population modelling. Here, we present results of a long-term (2002–2011) study on the movements, residency, growth and sex ratio of loggerhead turtles (Caretta caretta) in Amvrakikos Gulf (39°0′N 21°0′E), Greece, using satellite telemetry (N = 8) and ongoing capture–mark–recapture (CMR; N = 300 individuals). Individuals encountered at sea ranged from large juvenile to adult (46.2–91.5 cm straight carapace length) and demonstrated growth rates within published norms ( 44 % of captures above 65 cm straight carapace length), compared to region-wide female-biased hatchling production, indicating sex-biased survival or possible behavioural drivers for likelihood of capture in the region. Satellite tracking confirmed that some turtles establish discrete, protracted periods of residency spanning more than 1 year, whilst others migrated away from the site. These findings are underlined by CMR results with individual capture histories spanning up to 7 years, and only 18 % of individuals being recaptured.

Seabirds are well monitored and protected at their breeding grounds but spend most of their life at sea, where they are less well monitored and afforded little protection. In an attempt to address this dichotomy, attention has been directed toward establishing a network of marine reserves for seabirds, based largely on information from at-sea surveys and/or biotelemetry studies. Nevertheless, these approaches are costly, are typically only available for a limited number of locations, and not suitable for species that have either poor at-sea detectability or are unable to carry tracking devices. Here we develop a technique to identify important areas for breeding seabirds based on at-sea projections from colonies. Synthesising data from colony surveys with detailed information on population dynamics, foraging ecology and near-colony behaviour, we project colony-specific foraging distributions of the Northern gannet (Morus bassanus) at colonies in the UK, Ireland and France. We test the ability of our models to identify at-sea hotspots through comparison with existing data from biotelemetry studies and at-sea visual surveys. These models show a positive spatial correlation with one of the most intensive at-sea seabird survey datasets. While there are limitations to estimating at-sea distributions of seabirds, implemented appropriately, we propose they could prove useful in identifying potential Marine Protected Areas for seabirds. Moreover, these models could be developed to suit a range of species or whole communities and provide a theoretical framework for the study of factors such as colony size regulation.

The advent of telemetry has improved knowledge of the spatio-temporal distribution of marine species of conservation concern. Among the sea turtles, the movements of the hawksbill turtle Eretmochelys imbricata are among the least well described. We tracked 10 adult female hawksbill turtles by satellite after nesting in the Dominican Republic (DR) and describe a dichotomy in patterns of movement: some (n = 2) turtles remained in the DR, while others migrated to waters off Honduras and Nicaragua (n = 5) and the Bahamas (n = 1). Transmitters on 2 turtles failed during migration, before they reached their final foraging grounds. We present results from long tracking durations for 3 turtles, including 3 entire remigration intervals, high- lighting foraging ground and nest-site fidelity. Threats to hawksbill turtles are not well docu- mented for Nicaragua or neighbouring Honduras and represent a major information gap. We sug- gest that directing conservation efforts to regionally important foraging areas, such as those in Nicaragua, and strengthening national conservation in each nation with significant hawksbill nesting offers a clear way forward for the conservation of hawksbill turtles in the region.

Basking sharks Cetorhinus maximus have undergone widespread historic exploita- tion in the northeast Atlantic and are of conservation concern. A greater knowledge of their spatial and temporal habitat use is required to better inform subsequent monitoring and management strategies. Techniques such as light-based geolocation have provided great insights into individ- ual movements, but currently available data do not permit extrapolation to the population level. Public recording schemes may, however, help to fill shortfalls in data gathering, especially when analysed in conjunction with data from these other techniques. We analysed 11 781 records (from 1988 to 2008) from 2 public recording databases operating in the UK. We describe 3 sightings hotspots: western Scotland, Isle of Man and southwest England, and highlight the marked season- ality of basking shark sightings, which were at their greatest during the northeast Atlantic sum- mer (June to August). We further highlight a significant correlation between the duration of the sightings season in each year and the North Atlantic Oscillation, an atmosphereocean climate oscillation that has been linked to forcing of marine ecosystems. We augment patterns from public sightings records with effort-related data collected by boat-based transects at 2 regional sightings hotspots (western Scotland and southwest England). Analysis of reported body size data indicated that the annual proportion of small sharks ( 6 m) remained constant. These patterns may be indicative of a population recovery fol- lowing systematic harvesting in the 20th century.

Nesting by marine turtles in the Caribbean has declined considerably, mainly because of human exploitation, but there has previously been no monitoring in the Dominican Republic. We present the first detailed assessment of the status of marine turtle nesting in the country, based on surveys during 2006–2010. Nesting populations of hawksbill Eretmochelys imbricata and leatherback turtle Dermochelys coriacea are of regional importance and the green turtle Chelonia mydas is still present, although nesting in low numbers. The two main nesting sites are within protected areas: the Jaragua National Park in the south-west, important for leatherback turtles (mean of 126 nests per season), and Del Este National Park on Saona Island in the south-east, principally for hawksbill turtles (mean of 100 nests per season). Comparison with historical data suggests all rookeries are profoundly reduced in size. Although the main nesting beaches are within protected areas, illegal egg-take and meat consumption continues there, and also elsewhere in the country.

Situated in the northernmost part of Mozambique, the northern Querimbas Islands support some of the most diverse and pristine coral reefs in the Western Indian Ocean. The community-based turtle conservation programme that we developed on Vamizi Island has facilitated the identification and protection of a key nesting site for the green marine turtle Chelonia mydas in Mozambique, with a mean of 122 nests per year. The area is also used by nesting female and immature hawksbill turtles Eretmochelys imbricata. Nesting activity of green turtles was observed all year round, with a peak in the summer (February–March). Incubation periods of this species showed seasonal fluctuations inversely correlated with air temperature. Hatching success was high (87%) when nests were not lost through tidal overwash and erosion, which affected nearly 40% of all nests in 2007. Using satellite tracking of four green turtles nesting on Vamizi we identified foraging grounds in marine protected areas in Kenya, Tanzania and north-west Madagascar. Migratory routes of two individuals along the East African coast were generally neritic and all passed through the waters of multiple nations and as many as six marine conservation areas, emphasizing the importance of regional cooperation. Awareness programmes were also conducted with resource users, and the development of a community-based management system triggered the creation of a marine sanctuary by the local community.

Bycatch of non-target animals in small-scale fisheries poses a major threat to seabirds and marine mammals and turtles. This is also a problem for small-scale fisheries in Peru because of the magnitude of these fisheries and the important marine biodiversity in Peruvian waters. Here we describe how we implemented a novel approach to mitigate bycatch impacts on marine turtles in Peru. We used high-frequency (HF) two-way radio communication to exchange information with fishers. We sought data that would afford insights into fishing patterns and levels of turtle bycatch so that we could identify areas of high-density bycatch in real time and warn other fishers. In return we provided oceanographic and atmospheric information useful for the fishers. Radio communication also served as a platform to promote the use of safe handling and release techniques for incidentally caught animals. During the 24 months of the programme we communicated with over 200 vessels and with 200–1,400 fishers, who used primarily longlines, gillnets, jiggers, purse seiners and trawlers. Our findings suggest that HF radio communication is a useful tool (low cost and widely used by fishers, with extensive spatial coverage), helps build links with fishers that potentially reduces fishery impacts on marine turtles, and can also provide information on poorly documented fisheries and the relevant bycatch data associated with small-scale fishing practices.

Biologging data have provided important insights into the biology of marine mam- mals, sea turtles, birds, fish, and some invertebrates. These techniques have primarily targeted adult organisms. As a result, the early life histories of many marine species are still poorly under- stood. Technological advances have enabled attachment of smaller tags to young animals, although equipment limitations, access to and capture/handling of animals, and equipment and data recovery pose additional challenges to researchers. In this Theme Section, we highlight novel uses of biologging data on juvenile animals, including reviews of tagging efforts on multiple life- history stages and the integration of oceanographic data in tagging efforts.

The field of marine tagging and tracking has grown rapidly in recent years as tag sizes have decreased and the diversity of sensors has increased. Tag data provide a unique view on individual movement patterns, at different scales than shipboard surveys, and have been used to discover new habitat areas, characterize oceanographic features, and delineate stock struc- tures, among other purposes. Due to the necessity for small tag-to-body size ratio, tags have largely been deployed on adult animals, resulting in a relative paucity of data on earlier life his- tory stages. In this study, we reviewed tagging efforts on multiple life history stages for seabirds, marine mammals, marine turtles, and fish and enumerated studies focusing on each guild that tar- geted larvae, juveniles or hatchlings. We found that turtles and fish had higher proportion of stud- ies focusing on juveniles (>20%) than seabirds and marine mammals (

For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1 year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult.

The main nesting area for loggerhead turtles in the eastern Atlantic is in the Cape Verde Islands, largely restricted to the island of Boa Vista. Extensive monitoring demonstrated a globally significant population for the species despite a sustained high level of anthropogenic take of nesting females for local consumption. Through an extensive stratified monitoring program across the island in the seasons 2007–2009, we estimated a total of 13 955, 12 028 and 19 950 clutches in the 3 years, respectively. These values indicate that the mean number of nesting females averaged 3700. Considering that a female breed, on average, every 2.4 years, we estimate that the overall number of adult females in the population during these three seasons was 8900. These levels are much higher than those suggested in previous studies which were more constrained in spatial coverage. Our findings indicate that Cape Verde hosts the third largest nesting aggregation for this species in the world after the south-eastern US and Oman, with some sites having a particularly high density of nests, facilitating targeted monitoring and conservation. Consumption of sea turtle meat is a traditional practice in Cape Verde that continues despite national sea turtle protection laws. We estimated that 36, 18 and 5% of nesting females were harvested in the 3 years of the study, respectively. Increasing beach protection and monitoring, ongoing educational programs and cooperative projects with local communities are urgently needed to further safeguard the only major loggerhead nesting aggregation in the eastern Atlantic.

Conserving and managing populations of marine vertebrates can be complex when they occupy the waters of multiple nations, crossing heterogeneous legal and management landscapes. Hawksbill turtles ( Eretmochelys imbricata ) are subject to varying levels of use in Caribbean countries and their conservation and management is complicated by the extent to which they are a ‘shared’ resource. In 1997 and 2000, Cuba attempted to ‘downlist’ hawksbills from Cuban waters to CITES Appendix II to allow limited international trade. The research on movement and dispersal of hawksbills reported here was undertaken to better inform discussion about the impacts of their harvest. Flipper tagging and satellite tracking demonstrate that the majority of study turtles remained in Cuban territorial waters. Of 1170 hawksbills tagged (525 adults and 606 juveniles), 12% ( n = 143) were recaptured. All recaptured adults ( n = 16 males, 38 nesting females and 30 adult females in-water) were in Cuban waters. Of the 59 juveniles recaptured, only four recaptures were outside Cuban waters (Nicaragua = 2, Colombia = 1, USA = 1). Fourteen hawksbills tagged in the waters of other nations were recaptured in Cuban waters. We also satellite tracked 21 turtles (one adult male, ten nesting females and ten non-nesting adult females), of which five tags failed, 11 stayed in Cuban waters for the duration of transmissions (1–809 days) and five foraged in the waters of other nations (Mexico n = 1 an adult female; Honduras n = 2, both post-nesting turtles; Colombia n = 1 an adult female; and the eastern Lesser Antilles n = 1, an adult male), with differences for nesting and non-nesting turtles. Our results, demonstrating extended site fidelity within Cuban waters, suggest that strengthening national management within national jurisdictions that host hawksbill turtles is fundamental to improving regional conservation as a whole.

We followed the movements of 9 adult female olive ridley turtles Lepidochelys oli- vacea after nesting on Masirah Island, Oman, using satellite tracking. Their post-breeding migra- tions ranged from 85 to 796 km. Three individuals travelled north to foraging grounds in Pakistan, Iran and the United Arab Emirates. The other 6 turtles remained in Omani seas for extended peri- ods (mean ± SD = 171.3 ± 109.4 d; range = 40 to 310 d). These locally resident turtles experienced biannual cooling of sea temperatures due to the effect of the west Arabian Sea upwelling which was not experienced by those that migrated to the north. Indications of disparity in turtle size between foraging locations are identified for the first time in this species. The majority of turtles (8) settled in coastal areas of water depth 100 min) in water warmer than 21°C, which is a feature unique to olive ridleys amongst sea turtles. They dis- played a shift to shorter diving after breeding, indicating increased activity levels. The entire spa- tial footprint of olive ridley dispersal remained within a putative regional management unit (RMU) for this species in the western Indian Ocean, supporting its delineation. We reveal Oman's key role in conserving this demographic unit, with 6 turtles remaining within its national boundary. Our data add to the growing body of evidence that marine turtles show varied migration behav- iours within populations, thus complicating their management.

Identifying highly frequented areas is a priority for sea turtle conservation. Although juveniles represent the bulk of the population, a minority of studies have investigated their movement patterns. Six large juvenile loggerhead turtles that were found and released in an important foraging ground in the Mediterranean, the Tunisian continental shelf were tracked. Tracking data were obtained via satellite for periods ranging from 120 to 225 days and allowed the identification of high use areas. All turtles generally performed apparently non-directed, wandering movements in waters with a wide range of seafloor depths. They showed clear residential behaviour to the region with no evident seasonal pattern. Core areas of residence were in the neritic zone or on the edge of the continental shelf, largely overlapping among individuals, and were much smaller than residential oceanic areas reported elsewhere. When integrated into current knowledge, these results suggest an ecological-behavioural model of a gradual shift from a pelagic-vagile to a benthic-sedentary life style with progressive reduction of home ranges. They also highlight an area of the continental shelf and offshore waters as potential core foraging ground for large juvenile loggerhead turtles in the Mediterranean informing future spatial management for loggerhead turtles. Copyright © 2012 John Wiley & Sons, Ltd.

The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species, we still know surprisingly little about the extent of naturally occurring adaptive variation in heat-tolerance. Here, we show that the thermal tolerances of green turtle ( Chelonia mydas ) embryos in a single, island-breeding population have diverged in response to the contrasting incubation temperatures of nesting beaches just a few kilometres apart. In natural nests and in a common-garden rearing experiment, the offspring of females nesting on a naturally hot (black sand) beach survived better and grew larger at hot incubation temperatures compared with the offspring of females nesting on a cooler (pale sand) beach nearby. These differences were owing to shallower thermal reaction norms in the hot beach population, rather than shifts in thermal optima, and could not be explained by egg-mediated maternal effects. Our results suggest that marine turtle nesting behaviour can drive adaptive differentiation at remarkably fine spatial scales, and have important implications for how we define conservation units for protection. In particular, previous studies may have underestimated the extent of adaptive structuring in marine turtle populations that may significantly affect their capacity to respond to environmental change.

For organisms with temperature-dependent sex determination (TSD), skewed offspring sex ratios are common. However, climate warming poses the unique threat of producing extreme sex ratio biases that could ultimately lead to population extinctions. In marine turtles, highly female-skewed hatchling sex ratios already occur and predicted increases in global temperatures are expected to exacerbate this trend, unless species can adapt. However, it is not known whether offspring sex ratios persist into adulthood, or whether variation in male mating success intensifies the impact of a shortage of males on effective population size. Here, we use parentage analysis to show that in a rookery of the endangered green turtle ( Chelonia mydas ), despite an offspring sex ratio of 95 per cent females, there were at least 1.4 reproductive males to every breeding female. Our results suggest that male reproductive intervals may be shorter than the 2–4 years typical for females, and/or that males move between aggregations of receptive females, an inference supported by our satellite tracking, which shows that male turtles may visit multiple rookeries. We suggest that male mating patterns have the potential to buffer the disruptive effects of climate change on marine turtle populations, many of which are already seriously threatened.

We document patterns of distribution and relative abundance of marine megavertebrate fauna around Cornwall and the Isles of Scilly from a combination of aerial and boat-based surveying. Between January 2006 and November 2007, 20 aerial surveys were undertaken, comprising over 40 hours of on-effort flying time. In April to October of these years, 27 effort-corrected ferry surveys were also conducted from a passenger ferry travelling between Cornwall and the Isles of Scilly. Opportunistic sightings were also logged by the crew members of the ferry and another vessel travelling regularly along the same route on 155 days. Ten megavertebrate species were sighted: basking sharks Cetorhinus maximus, sunfish Mola mola, common dolphins Delphinus delphis, harbour porpoise Phocoena phocoena, grey seals Halichoerus grypus, Risso's dolphins Grampus griseus, bottlenose dolphins Tursiops truncatus, minke whales Balaenoptera acutorostrata, long-finned pilot whales Globicephala melas and killer whale Orcinus orca. During aerial surveys, 206 sighting events of seven species were made, compared with 145 sighting events of eight species during ferry surveys and 293 sighting events of 10 species from opportunistic ship-board data collection efforts. Seasonal and spatial patterns in species occurrence were evident. Basking sharks were the most commonly-sighted species in the region and were relatively abundant throughout the estimated 5 km-wide strip of coastal waters covered by the aerial surveys, during spring and summer. Ferry surveys and opportunistic vessel-based sightings data confirmed that the distribution of surface-feeding aggregations of this species was largely around the coasts. Despite the limited scope of this study, it has provided valuable baseline data, and possible insights into the marine biodiversity of the region.

Patterns of distribution, key biometric parameters and home range extent were determined for hawksbill turtles at Lighthouse Reef Atoll (LRA), Belize over two field seasons (16 days, 2009; 30 days, 2010). Relative abundance was determined using 49 sightings transects (≈ 1 km) distributed across the atoll and of all turtles encountered (n = 68), 91% were immature (CCL min ≤ 65 cm). Habitat type was significantly correlated with abundance, with more turtles encountered on the coral reef than in the lagoon (GzLMM, χ 2 2 = 6.85, p − 1 , CPUE lagoon = 0.62 turtles h − 1 ). Hawksbills were also significantly more abundant within protected areas (GzLMM, χ 2 1 = 8.69, p − 1 h − 1 ; CPUE Half Moon Caye Natural Monument (HMCNM) = 2.34 turtles h − 1 ; outside boundaries = 0.88 turtles h − 1 ). Of 26 captures, 19 focal individuals were equipped with ultrasonic transmitters for active acoustic telemetry, and tracked for 6–25 days (n = 10, 2009; n = 9, 2010). Spatial habitat utilisation was found to be highly variable, with large areas of overlap between distinct home ranges. Home range averaged 31.2 ha ± 32.6 (range 5.1–111.3 ha) for the juveniles that were successfully tracked (n = 15), with maximum displacement in the order of 1.8 km ± 1.0 (range 0.5–4.0 km) and net displacement at 1.2 km ± 0.9. This offshore atoll constitutes an important developmental habitat for the regional population and although our tracking durations were limited, home range of juvenile hawksbills at this site is significantly more expansive than that documented elsewhere.

Summary 1. Over the last few decades, evidence of marine vertebrate bycatch has been collected for a range of industrial fisheries. It has recently been acknowledged that large impacts may also result from similar interactions with small-scale fisheries (SSF) due largely to their diffuse effort and large number of vessels in operation. Marine mammals, seabirds, turtles as well as some shark species have been reported as being impacted by SSF worldwide. 2. From 2000 to 2007, we used both shore-based and onboard observer programmes from three SSF ports in Peru to assess the impact on marine turtles of small-scale longline, bottom set nets and driftnet fisheries. 3. We reported a total of 807 sea turtles captured, 91AE8% of which were released alive. For these three sites alone, we estimated c. 5900 turtles captured annually (3200 loggerhead turtles Caretta caretta, 2400 green turtles Chelonia mydas, 240 olive ridleys Lepidochelys olivacea and 70 leatherback turtles Dermochelys coriacea). 4. SSF in Peru are widespread and numerous (>100 ports, >9500 vessels, >37 000 fishers), and our observed effort constituted c. 1% of longline and net deployments. We suggest that the number of turtles captured per year is likely to be in the tens of thousands. Thus, the impacts of Peruvian SSF have the potential to severely impact sea turtles in the Pacific especially green, loggerhead and leatherback turtles. 5. Implications of the human use of turtle products as ‘marine bushmeat’ are also raised as an important issue. Although such utilization is illegal, it is difficult to foresee how it can be managed without addressing the constraints to the livelihoods of those depending almost entirely on coastal resources. 6. Syntheses and applications. Our analysis demonstrates that, despite logistical challenges, it is feasible to estimate the bycatch per unit of effort in SSF by combining methods that account for fishing effort and bycatch, such as using onboard and shore-based observers. We highlight sea turtle bycatch in SSF in the southeast Pacific as a major conservation concern but also suggest possible paths for mitigation.

The post-capture movements made by loggerhead sea turtles Caretta caretta in the southeastern Pacific Ocean were monitored from 2003 to 2007. Fourteen loggerhead turtles were fit- ted with satellite transmitters and released off the coast of Peru. All turtles were juveniles (curved carapace length range: 40.5 to 68.5 cm) incidentally captured by small-scale longline fishing vessels from southern or central Peru. Track durations were highly variable (mean ± SD: 143 ± 90 d; range: 8 to 297 d) with no clear signs of immediate post-release mortality. Upon release, all turtles moved off- shore beyond the continental shelf. Eight of 11 turtles tracked for >60 d had final displacements of

Cetacean species and their habitats are under threat and effective marine management mitigation strategies require knowledge and understanding of cetacean ecology. This requires data that are challenging and expensive to obtain; incidental sightings/strandings data are potential underused resources. In this study, incidental cetacean sightings (N = 6631) and strandings (N = 1856) in coastal waters of Cornwall, south-west Britain (1991 to 2008) were analysed for evidence of spatial and temporal patterns or trends. Eighteen species were recorded sighted and/or stranded; key species were identified as bottlenose dolphin (Tursiops truncatus), harbour porpoise (Phocoena phocoena), common dolphin (Delphinus delphis), Risso's dolphin (Grampus griseus) and minke whale (Balaenoptera acutorostrata). There were significant decreases in bottlenose dolphin sightings and pod size but an increase in harbour porpoise and minke whale sightings. Cetacean strandings showed a recent decrease over time although there was a significant positive trend in harbour porpoise strandings that correlated with sightings. Incidence of sightings and strandings were both greater on the south coast than the north coast. When Marine Tour Operator data were analysed, distinct species-specific inshore and offshore habitat use was evident. With rigorous interrogation and editing, significant patterns and trends were gained from incidentally collected data, highlighting the importance of public engagement with such recording schemes and the potential of these underused resources.

Aim Although satellite tracking has yielded much information regarding the migrations and habitat use of threatened marine species, relatively little has been published about the environmental niche for loggerhead sea turtles Caretta caretta in north-west Atlantic waters. Location North Carolina, South Carolina and Georgia, USA. Methods We tracked 68 adult female turtles between 1998 and 2008, one of the largest sample sizes to date, for 372.2 ± 210.4 days (mean ± SD). Results We identified two strategies: (1) ‘seasonal’ migrations between summer and winter coastal areas (n = 47), although some turtles made oceanic excursions (n = 4) and (2) occupation of more southerly ‘year-round’ ranges (n = 18). Seasonal turtles occupied summer home ranges of 645.1 km2 (median, n = 42; using α-hulls) predominantly north of 35 ° latitude and winter home ranges of 339.0 km2 (n = 24) in a relatively small area on the narrow shelf off North Carolina. We tracked some of these turtles through successive summer (n = 8) and winter (n = 3) seasons, showing inter-annual home range repeatability to within 14.5 km of summer areas and 10.3 km of winter areas. For year-round turtles, home ranges were 1889.9 km2. Turtles should be tracked for at least 80 days to reliably estimate the home range size in seasonal habitats. The equivalent minimum duration for ‘year-round’ turtles is more complex to derive. We define an environmental envelope of the distribution of North American loggerhead turtles: warm waters (between 18.2 and 29.2 °C) on the coastal shelf (in depths of 3.0–89.0 m). Main conclusions Our findings show that adult female loggerhead turtles show predictable, repeatable home range behaviour and do not generally leave waters of the USA, nor the continental shelf (

1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic animals. We suggest that maternal thermoregulatory behaviour in marine turtles, and many other reptiles, is consistent with a strategy of adaptively increasing body temperatures to accelerate egg maturation.

Linking foraging and breeding habitats is key to the understanding of behaviour, ecol- ogy and demography of migratory species. Establishing such connections has long been hampered by the logistical problems of following individuals between foraging and breeding areas, especially in the marine realm. We used variation in nitrogen stable isotope patterns between 2 foraging regions of loggerhead sea turtles Caretta caretta determined from samples of satellite-tracked indi- viduals to assign untracked turtles to a foraging region. We sought to enhance determination of the relative importance of geographically separated foraging regions and to investigate the relationship between fitness correlates and inferred migratory strategies. Of 18 turtles followed by satellite tracking from Zakynthos (Greece), 10 moved north to foraging areas in the Adriatic Sea and the Gulf of Amvrakikos and 8 moved south to foraging areas off the coast of North Africa. Of 51 untracked individuals sampled for stable isotope analysis, we considered the stable isotope signature of 47 to qualify for assignment to foraging areas in the north (n = 22) and south (n = 25). Females foraging north were significantly larger (curved carapace length), and the former group laid larger clutches (even after correction for body length) than turtles foraging south, a fact that can be interpreted as a carry-over effect. Combining satellite tracking with stable isotope signatures in marine turtles opens new perspectives into how forensic tracking methodologies may be used to scale up knowl- edge from electronic tracking of a limited number of individuals to sample sizes that are more mean- ingful from a population perspective.

Fisheries are considered a major driver of population declines for many marine vertebrate species, and yet for some, data on the levels of direct catch are lacking, often due to the logistical challenges in assessing artisanal fisheries in remote and developing regions. Using community members to collect data can provide access to a greater wealth of information than that obtained by local or foreign researchers, often at a reduced financial cost. We monitored the harvest of marine turtles at 12 major villages in Madagascar using community members as data collectors (sous collecteurs) from each village, at a total cost of

Small-scale fisheries in Peru constitute an important source of food and employment for coastal communities where fish is the single most important natural resource. Utilizing official statistics and extensive survey data from 30 fishing ports and by onboard observers operating from 11 ports, we review how these fisheries grew from 1995 to 2005, and provide insights into the relative importance of different fishing gears and their modes of operation. Small-scale fisheries operate along the entire Peruvian coast and have continued expanding in number of vessels and fishers in all geopolitical regions except one. Nationwide, the number of fishers grew by 34% from 28 098 to 37 727 and the number of vessels increased by 54% from 6268 to 9667. At 30 harbors, the number of vessels increased for purse seiners (17.8%) and longliners (357.4%), while gillnets decreased (−14.5%). These dramatic changes could jeopardize the sustainability of these fisheries and the livelihoods of those who depend upon them, especially considering the limited capacity for management. Despite increase in effort, catch and catch per vessel have decreased, especially in some of the sub-regions that previously constituted the majority of effort and landings, raising concerns regarding their sustainability. Of the fishing gears monitored, gillnets were shown to have the most frequent interactions with threatened taxa such as marine mammals, seabirds and sea turtles. The total length of gillnets set in Peru was estimated at >100 000 km of net per year, about 14 times the length used by the Taiwanese high seas driftnet fleet in the Pacific before it was banned. Longlines, although shown to be a more efficient fishing method (economically and in terms of selectivity), still had bycatch of turtles and seabirds, and marine mammals are targeted to be used as bait. We conservatively estimate that longline vessels operating in Peru set an average of 80 million hooks per year; equivalent to one-third of the annual effort of the global industrial swordfish longline fishery. We conclude that, despite their definition as small-scale, the magnitude of these fleets and their fishing effort are vast and are of concern with regard to their long term sustainability and their impacts and interactions with large marine vertebrates. We highlight the need for increased research and management measures to ensure the long term viability of these fisheries.

Centre for Ecology and Conservation, School of Biosciences, University of Exeter Department of Animal Ecology, Lund University, Sweden c SEATURTLE.org, U.S.A. Ascension Island Turtle Group, Ascension Island, South Atlantic Wildlife Conservation Society, Gabon f Institute of Environmental Sustainability, Swansea University, U.K. Dipartimento di Biologia, University of Pisa, Italy Ascension Island Conservation, Ascension Island, South Atlantic

The marine otter ( Lontra felina ) inhabits patches of rocky coastline from central Peru to southern Chile and is classified as Endangered by the IUCN. Given the limited information available about the species, we set out to assess marine otter diet with a view to detecting latitudinal differences, and to assess marine otter activity budgets and interspecific interactions (including anthropogenic) at Peruvian fishing villages and to compare results with similar Chilean studies. Nine study sites from central Chile to southern Peru were sampled for otter spraints to assess relative frequency of prey types and two fishing ports in southern Peru were monitored through focal and scan observations to assess activity patterns, interspecific interactions, habitat use patterns, and dive durations. Results indicate that toward the northern part of its range, crustaceans become less important and fish more important in the diet. Interactions were observed between marine otters and other species, including stray dogs and cats. The strong dependence of marine otters on the availability of safe rocky shelters, and the species' apparent tolerance to living alongside humans raise conservation concerns about vulnerability to anthropogenic threats. These factors, if not correctly managed, could turn some of these rocky seashore patches into population sinks.

One potential approach to combat the impacts of climate change is the expansion of renewable energy installations, leading to an increase in the number of wave-powered marine renewable energy installations (MREIs). The consequences of increased use of these devices for birds are unknown. Here we describe the wave-powered energy-generating devices currently either operational or in development and review the potential threats and benefits of these to marine birds, their habitats and prey. Direct negative effects include risk of collision, disturbance, displacement and redirection during construction, operation and decommissioning. Above-water collision is a particular concern with wind-powered devices, but, because of their low profiles, the collision risk associated with wave-powered devices is likely to be much lower. Conversely, wave devices also pose the novel threat of underwater collision. Wave-energy-generating devices may indirectly impact marine birds by altering oceanographic processes and food availability, with implications for trophic cascades. Through appropriate mitigation, wave-powered MREIs offer the potential to enhance habitats. Direct positive effects may include provision of roosting sites, and indirect positive effects may include prey aggregation due to suitable substrates for sessile organisms or because they act as de facto protected areas. The cumulative effect of these could be the improvement and protection of foraging opportunities for marine birds. Recent studies have been critical of the methods used in the assessment of wind-powered MREI impacts, which lack sufficient sample sizes, controls or pre-development comparisons. Here we suggest solutions for the design of future studies into the effects of MREIs. Wave-powered MREIs are certain to become part of the marine environment, but with appropriate planning, mitigation and monitoring they have the potential to offer benefits to marine birds in the future.

Understanding the ecological roles performed by an individual species requires knowledge from a wide range of disciplines; here we analyze the epibiont–host relationship found in marine turtles. During the study we recorded five new species of sea turtle epibiont: Laomedea flexuosa, Caprella fretensis, Hyale nilssoni, Hyale schmidti, Parasinelobus chevreuxi; as part of a total of nine zoological epibionts present on 35 female green turtles (Chelonia mydas) and 100 loggerhead turtles (Caretta caretta) nesting in Cyprus. The two most commonly occurring epibionts were acorn barnacles Chelonibia testudinaria and Chelonibia caretta, with larger specimens of both species recorded on loggerhead turtles. We analyzed the spatial distribution of these two barnacle species upon the carapaces of their hosts. Specimens of C. testudinaria situated on the anterior half of the carapace were larger than those located at the posterior. A significantly larger proportion of loggerhead turtles (52.5%) hosted epibionts in comp...

We evaluate the conservation status and threats faced by sea turtle nesting populations at Bioko Island, Equatorial Guinea (Central Africa). Beaches were monitored to obtain a detailed sea turtle nest census and, where possible, tagging of adult females was undertaken. Four sea turtle species were found nesting in the area: the green turtle (Chelonia mydas), the leatherback (Dermochelys coriacea), the olive ridley (Lepidochelys olivacea) and the hawksbill (Eretmochelys imbricata); with the former two species nesting in regionally important numbers. Nesting activity was concentrated between November and February, with a peak in December-January. Tagging and recapture of green turtles in two consecutive seasons suggested an estimated 560 (interquartile range: 420-1,681) and 414 (interquartile range: 190-1,255) nesting females in the area, respectively. Estimated numbers of nesting leatherbacks ranged from 123 to 215 and 243 to 293 in the first and second season, respectively. The other two species were less abundant (olive ridley: 19-29 and 28-43; hawksbill: 4-10 and 2 turtles). Data were compared with more recent surveys in the area and contextualised with information on human related threats. Despite the size of nesting stocks, ongoing permitted and illegal take of adult turtles at the nesting site constitutes a serious threat for these breeding aggregations. Additionally, tag returns from throughout the Gulf of Guinea suggest that the level of take in regional fisheries may also be a major threat.

This study investigated the phenology, patterns of haul-out habitat use and distribution of the grey seal around Cornwall and the Isles of Scilly. A full census of the coast was carried out by boat over 4 days, in order to make a full count of seals hauled out and close to the coast, and to document all haul-out sites. Regular land-based surveys were made of three haul-out sites in Cornwall, to investigate the effects of spatial, temporal and environmental factors on seal haul-out behaviour. Data from 2004 to 2007 were analysed to describe long-term temporal variation in seal abundance at two haul-out sites. A total of 592 sightings were made along the coast of Cornwall and the Isles of Scilly over the four-day census period; 476 of these sightings (80.4%) were recorded at six main haul-out sites. The highest proportion of seals was observed at three haul-out areas on the Isles of Scilly. In Cornwall, seals were observed in higher numbers on the north coast, where the three largest mainland haul-out sites were documented, than on the south coast. At one key haul-out site in Cornwall, a distinct seasonal pattern was evident in data collected between 2004 and 2007, with higher numbers of seals present during the moulting and breeding seasons than over the summer months. There was considerable inter-annual variability in peak seal abundance, during the moulting season, at this site. There was no significant variation in haul-out behaviour with tidal state at this site, although haul-out counts were generally highest at mid-ebb tides. Data on seal abundance, distribution and haul-out behaviour may aid the designation of Special Areas of Conservation for the protection of grey seals in Cornwall and the Isles of Scilly.

Summary 1. Comprehensive knowledge of the fundamental spatial ecology of marine species is critical to allow the identification of key habitats and the likely sources of anthropogenic threats, thus informing effective conservation strategies. 2. Research on migratory marine vertebrates has lagged behind many similar terrestrial animal groups, but studies using electronic tagging systems and molecular techniques offer great insights. 3. Marine turtles have complex life history patterns, spanning wide spatio-temporal scales. As a result of this multidimensional complexity, and despite extensive effort, there are no populations for which a truly holistic understanding of the spatial aspects of the life history has been attained. There is a particular lack of information regarding the distribution and habitats utilized during the first few years of life. 4. We used satellite tracking technology to track individual turtles following nesting at the green

Tracking fine-scale movements in relation to threats is fundamental to the management of exploited marine species, yet there is considerable difficulty associated with gathering such data at sea. By combining a capture-recapture study with deployment of time-depth recorders (TDRs) and ultrasonic tags, we elucidated distribution and daily movements of juvenile green turtles Chelonia mydas exposed to a legal marine turtle fishery in the Cayman Islands. For instrumented turtles, dis- tinct diel activity patterns were observed: dives during the day were shorter and more active than those at night, implying diurnal foraging and nocturnal resting. Spatially, while capture and recap- ture locations suggested fidelity to a shallow lagoon, when turtles were fitted with TDRs and ultra- sonic tags we demonstrated that they regularly moved out of the lagoon and onto the reef, where they could legally be captured in the marine turtle fishery. Our results are thus novel and valuable in a management context in that we demonstrated that seemingly protected aggregations of juvenile green turtles within a lagoon were, in fact, exposed to legal capture on a near-daily basis. This emphasizes the importance of assessing diel activity patterns of juvenile marine turtles, particularly with respect to directed take and other threats.

SUMMARY Marine turtles utilise terrestrial and marine habitats and several aspects of their life history are tied to environmental features that are altering due to rapid climate change. We overview the likely impacts of climate change on the biology of these species, which are likely centred upon the thermal ecology of this taxonomic group. Then, focusing in detail on three decades of research on the loggerhead turtle (Caretta caretta L.), we describe how much progress has been made to date and how future experimental and ecological focus should be directed. Key questions include: what are the current hatchling sex ratios from which to measure future climate-induced changes? What are wild adult sex ratios and how many males are necessary to maintain a fertile and productive population? How will climate change affect turtles in terms of their distribution?

Biologging technology allows researchers to take measurements from free-ranging ani- mals as they move undisturbed through their environment. Recent advances in biologging technol- ogy, including electronic tag miniaturization and improved animal movement models, have revolu- tionized our understanding of the ecology of top predators and have permitted observations well beyond the reach of standard measurement techniques. Engineering has provided the biologging community with ever more sophisticated tags, and advances in the application of statistical methods to interpret these data have yielded powerful new tools for understanding animal behavior. The tech- nology has also reached sufficient sophistication and reliability such that the data collected is often equivalent to industry standards for environmental sampling, which has led to profound advance- ments in the marine realm, where the sheer vastness, in 3 dimensions, limits our ability to observe. Biologging data is now being increasingly applied to marine management and conservation policy. In this introduction, we highlight a few of the research themes presented at the Third International Conference on Biologging Science, and comment on the future challenges of biologging science.

Acquiring knowledge of the spatial ecology of many aquatic species, particularly their juvenile life stages, is challenging when they are small in size; this limits the attachment of tracking devices that routinely provide spatially explicit information on larger juveniles and adults. Using depth utilisation data gathered by time-depth recorders, we inferred patterns of habitat utilisation of juvenile hawksbill turtles Eretmochelys imbricata occupying a shallow reef system in the Caribbean. Hawksbill turtles (n = 9, curved carapace length = 42.3 ± 9.7 cm, range = 27.7 to 60.0 cm) demon- strated diel patterns of behaviour, with greater activity and shorter dives during the day (mean dura- tion = 7.5 ± 5.0 min, range = 2.6 to 34.4 min) and longer, less active dives during the night (mean dura- tion = 16.6 ± 12.0 min, range = 2.5 to 61.5 min). A level of fidelity to sites facilitated recaptures (mean minimum straight-line distance from release of TDR-equipped turtles to their subsequent recapture locations = 0.9 ± 0.9 km, range = 0.01 to 2.3 km), but recapture success after 130 h, over a 43 d period, was relatively low: of 19 individuals instrumented, 9 were recaptured. From depth records, i.e. max- imum depths achieved, it was clear that some recaptured individuals moved considerably during the monitoring period; 3 individuals moved to deeper waters, with minimum possible straight-line move- ment distances from their capture sites of 3.7 to 9.2 km. These findings emphasize the likely influence of habitat structure on site fidelity and further highlight that data from traditional capture-mark- recapture studies could lead to an underestimation of home-range size.

Where mechanisms inherent within the biology of a species affect individual fitness at low density, demographic-scale depensation may occur, hastening further decline and leading ultimately to population extirpation and species extinction. Reduction in fertility at low population densities has been identified in marine and terrestrial species. Using data on hatch success and hatchling-emergence success as proxies for fertilization success, we conducted a global meta-analysis of data from breeding aggregations of green turtles (Chelonia mydas) and loggerhead turtles (Caretta caretta). We found that there has been no reduction in fertility in small nesting aggregations in either of these species worldwide. We considered mechanisms within the mating strategies and reproductive biology of marine turtles that may allow for novel genetic input and facilitate enhanced gene flow among rookeries. Behavioral reproductive mechanisms, such as natal philopatry and polyandry, may mitigate potential impacts of depensation and contribute to the resilience of these species.

We detail the first direct, at sea monitoring of small cetacean interactions with Peruvian artisanal drift gillnet and longline fisheries. A total of 253 small cetaceans were captured during 66 monitored fishing trips (Gillnet: 46 trips; Longline: 20 trips) from the port of Salaverry, northern Peru (8 o 14 0 S, 78 o 59 0 W) from March 2005 to July 2007. The most commonly captured species were common dolphins (Delphinus spp.) (47%), dusky dolphins (Lagenorhynchus obscurus) (29%), common bottlenose dolphins (Tursiops truncatus) (13%) and Burmeister’s porpoises (Phocoena spinipinnis) (6%). An estimated 95% of common dolphin bycatch was of long-beaked common dolphins (Delphinus capensis). Overall bycatch per unit effort for gillnet vessels (mean ± sd) was estimated to be 0.65 ± 0.41 animals.set � 1 (range 0.05–1.50)

Reproduction was studied in the land crab Johngarthia lagostoma on Ascension Island in the central South Atlantic from 2005 to 2008. Both sexes are mature by 60-70 mm carapace width (the sample . 4,000 crabs consisted almost entirely of mature specimens). Breeding occurs around the east and south shores of the island, but was studied predominantly at the only easily accessible site at North East Bay. The annual breeding migration extends from January to May, with peak migration in March in most years. The intensity of migration varies between years, and is not obviously related to rainfall. There is lunar entrainment, with increased numbers at the shore in the first quarter, but largest numbers in the last quarter. Both males and females migrate, but with females in greater numbers. At the shore 80% of the crabs are females. A few females mate and lay eggs in the upland residential areas, a greater number do so on the migration route, but the majority only after reaching the shore. Reproductive investment per brood averaged 5% on a dry weight basis, and fecundity averaged 72,000 eggs.

The introduction of mammal predators to islands often results in rapid declines in the number and range of seabirds. On Ascension Island the introduction of cats in 1815 resulted in extirpation of large seabird colonies from the main island, with relict populations of most species persisting only in cat-inaccessible locations. We describe the eradication of feral cats from this large and populated island. The campaign had to minimize risk to humans and maintain domestic animals in a state that prevented them reestablishing a feral population. Feral cat numbers declined rapidly in response to the strategic deployment of poisoning and live trapping, and cats were eradicated from the island within 2 years. During the project 38% of domestic cats were killed accidentally, which caused public consternation; we make recommendations for reducing such problems in future eradications. Since the completion of the eradication campaign cat predation of adult seabirds has ceased and five seabird species have recolonized the mainland in small but increasing numbers. Breeding success of seabirds at Ascension was low compared to that of conspecifics elsewhere, and the roles of food availability, inexperience of parent birds and black rat predation in causing this warrant further investigation. It is likely that the low breeding success will result in the rate of increase in seabird populations being slow.

This study reviews the status of marine turtles in the Turks and Caicos Islands (TCI) using data gathered during a multidisciplinary study involving field surveys, questionnaire-based interviews, and molecular genetics between 2002 and 2006. Large aggregations of foraging turtles in the archipelago's waters are dominated by juvenile green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata), with provisional mixed-stock analysis of these species suggesting that the aggregations originate predominantly from larger and relatively proximate source rookeries in the Wider Caribbean region. This study also suggests that the islands host remnant nesting populations of turtles, with hawksbill turtle nests recorded more frequently than green and loggerhead turtle (Caretta caretta) nests. The TCI islanders retain a culture of turtle use, with the current regulated and legitimate harvest likely to be one of the largest among the Caribbean Islands. This study suggests that historic and current har...

Despite intense interest in conservation of marine turtles, spatial ecology during the oceanic juvenile phase remains relatively unknown. Here, we used mixed stock analysis and examination of oceanic drift to elucidate movements of hawksbill turtles (Eretmochelys imbricata) and address management implications within the Caribbean. Among samples collected from 92 neritic juvenile hawksbills in the Cayman Islands we detected 11 mtDNA control region haplotypes. To estimate contributions to the aggregation, we performed 'many-to-many' mixed stock analysis, incorporating published hawksbill genetic and population data. The Cayman Islands aggregation represents a diverse mixed stock: potentially contributing source rookeries spanned the Caribbean basin, delineating a scale of recruitment of 200-2500 km. As hawksbills undergo an extended phase of oceanic dispersal, ocean currents may drive patterns of genetic diversity observed on foraging aggregations. Therefore, using high-resolution Aviso ocean current data, we modelled movement of particles representing passively drifting oceanic juvenile hawksbills. Putative distribution patterns varied markedly by origin: particles from many rookeries were broadly distributed across the region, while others would appear to become entrained in local gyres. Overall, we detected a significant correlation between genetic profiles of foraging aggregations and patterns of particle distribution produced by a hatchling drift model (Mantel test, r = 0.77, P < 0.001; linear regression, r = 0.83, P < 0.001). Our results indicate that although there is a high degree of mixing across the Caribbean (a 'turtle soup'), current patterns play a substantial role in determining genetic structure of foraging aggregations (forming turtle groups). Thus, for marine turtles and other widely distributed marine species, integration of genetic and oceanographic data may enhance understanding of population connectivity and management requirements.

Summary 1. The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources. 2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future. 3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts. 4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries. 5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits. 6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration.

For species with temperature-dependent sex determination, such as marine turtles, global climate change poses numerous threats. At the nesting beach, rising temperatures are predicted to further skew already female-biased sex ratios and increase embryonic mortality; sea-level rise and resultant coastal squeeze may leave few alternative breeding habitats in developed regions. As a result, clutch relocation, a commonly used management tool to reduce egg loss, may become necessary for safeguarding populations. Although studies have examined the impact of relocation on clutch success, few have examined the impact of this practice on the sex or phenotypic characteristics of hatchlings produced. We used a randomized block design experiment to examine effects of relocation on green turtle (Chelonia mydas) clutches. We compared hatching success, thermal conditions, and size (length and mass) of hatchlings from in situ control clutches with those subjected to 2 relocation methods, while controlling for maternal and other environmental effects. Relocated clutches did not vary significantly from control clutches in incubation temperature or inferred sex ratios during the critical middle third of incubation when sex is thought to be determined. Hatchling size was also unaffected by relocation. Both relocation methods, however, resulted in a 20% reduction in hatching success in comparison to in situ clutches. Clutch relocation is, however, likely to affect the population primary sex ratio, when clutches are relocated from sites in proximity to the sea where tidal inundation is a threat. Here, cooler conditions are likely to produce more males than are the warmer female-producing temperatures higher up the beach. For clutches at risk, relocation is a viable process and does not appear to affect hatchling size or predicted sex ratios if relocation sites are selected in areas utilized by other females. We urge caution, however, when moving clutches from potentially male-producing sites, particularly given predicted impacts of climate change on already female-biased sex ratios.

For many marine megavertebrate species it is challenging to derive population estimates and knowledge on habitat use needed to inform conservation planning. For marine turtles, the logistics required to undertake comprehensive ground-based censuses, across wide spatial and temporal scales, are often insurmountable. This frequently leads to an approach where a limited number of index nesting beaches are monitored in great detail by foot. In this study we use nationwide aerial surveying interfaced with ground assessments across three seasons of leatherback turtle nesting in Gabon (Equatorial West Africa), highlighting the importance of a synoptic approach to marine turtle monitoring. These surveys allow the first complete population assessment of this nesting aggregation to be made, identifying it as the world’s largest for the species (36,185–126,480 clutches, approximating to 5865–20,499 breeding females per annum and a total estimate of 15,730 to 41,373 breeding females). Our approach also serendipitously provides insights into the spatial appropriateness of Gabon’s protected areas network, for example (mean ± 1SD) 79 ± 6% (range 67–86%) of leatherback turtle activities recorded during aerial surveys (n = 8) occurred within protected areas (345 km, 58%, of surveyed coastline). We identify and discuss sources of potential error in estimating total nesting effort from aerial surveying techniques and show that interannual variation in nesting is considerable, which has implications for the detection of statistically significant changes in population size. Despite its relative costliness per day, aerial surveying can play an important role in providing estimates of relative population abundance of large vertebrates dispersed over extensive areas. Furthermore, it can provide data on habitat use and deliver real-time information on the spatial efficacy of protected area networks.

Many marine turtle habitat utilization studies have historically relied on inferences from logged data or direct visual observation. Here we remotely investigate aspects of the habitat utilization of inter-nesting female green turtles (Chelonia mydas) nesting on the Mediterranean island of Cyprus. Using an animal-borne digital video camera set to take only still images, with an integrated time-depth recorder, we recorded a total of 2,375 images and 2,899 dives for two nesting female green turtles. Both turtles spent over 80% of their time at depths of 5 m or less. Photographic evidence allowed us to categorize sub-surface behaviors from 66 of the deeper dives (turtle A with 40 dives and turtle B with 26 dives) containing more than 900 images into three categories: swimming, probable foraging and resting. Methodologically, our study highlights future utility in using camera technologies to clarify at-sea behavior of marine organisms, with a view to generating reliable time budgets.