Formulating management strategies for mobile marine species is challenging, as knowledge is required of distribution, density, and overlap with putative threats. As a step towards assimilating knowledge, ecological niche models may identify likely suitable habitats for species, but lack the ability to enumerate species densities. Traditionally, this has been catered for by sightings-based distance sampling methods that may have practical and logistical limitations. Here we describe a novel method to estimate at-sea distribution and densities of a marine vertebrate, using historic aerial surveys of Gabonese leatherback turtle (Dermochelys coriacea) nesting beaches and satellite telemetry data of females at sea. We contextualise modelled patterns of distribution with putative threat layers of boat traffic, including fishing vessels and large ship movements, using Vessel Monitoring System (VMS) and Automatic Identification System (AIS) data. We identify key at-sea areas in which protection for inter-nesting leatherback turtles could be considered within the coastal zone of Gabonese Exclusive Economic Zone (EEZ). Our approach offers a holistic technique that merges multiple datasets and methodologies to build a deeper and insightful knowledge base with which to manage known activities at sea. As such, the methodologies presented in this study could be applied to other species of sea turtles for cumulative assessments; and with adaptation, may have utility in defining critical habitats for other central-place foragers such as pinnipeds, or sea bird species. Although our analysis focuses on a single species, we suggest that putative threats identified within this study (fisheries, seismic activity, general shipping) likely apply to other mobile marine vertebrates of conservation concern within Gabonese and central African coastal waters, such as olive ridley sea turtles (Lepidochelys olivacea), humpback dolphins (Sousa teuszii) and humpback whales (Megaptera novaeangliae).

We sampled 17 nesting sites for loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in Cyprus. Microplastics (

© 2016 John Wiley & Sons Ltd. Aims: Effective conservation of threatened or endangered species requires a robust understanding of their spatio-temporal distribution. Although a huge amount is known about the movements of Atlantic adult sea turtles, much less is known about juvenile turtles, and much of the life history model is therefore inferred. We set out to describe the spatio-temporal distribution of juvenile loggerheads turtles found around the Canary Islands. Location: Eastern North Atlantic Ocean. Methods: Between 1999 and 2012, we satellite-tracked 24 healthy large juvenile loggerhead turtles (mean straight carapace length = 47.4 cm, range = 34.6-54.5 cm) captured in the waters around the Canary Islands. We describe their regional distribution, identify high-use areas and create a model for habitat suitability using minimum convex polygons, density rasters and ensemble ecological niche modelling, integrated with physical and biological environmental data. Results: Turtles used a huge oceanic area (2.5 million km2) with particularly high usage around the Canary Islands, Spain, Portugal, Morocco and Western Sahara. In spring and summer, turtles generally moved further north towards the Iberian Peninsula. Ecological niche modelling identified sea surface temperature as the most important contributory variable to the habitat models. We also recorded three juvenile turtles making westward migrations away from the eastern Atlantic Ocean, presumably back towards their original natal beaches near sexual maturity. Main conclusions: the results of the present study provide insight into a significant knowledge gap on the spatio-temporal distribution of large juvenile loggerhead turtles in the eastern Atlantic Ocean. The data highlight that turtles occupy a vast open oceanic area, which hampers the ability of static conservation approaches to afford effective protection. However, ensemble ecological niche modelling highlights key suitable habitat for juvenile loggerhead turtles, which could be used in dynamic conservation protection.

The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these two distinct behavioural strategies. We also investigate how these predicted habitat niches may alter under the influence of climate change induced oceanic temperature rises. We further contextualise our niche models with fisheries catch data and knowledge of fisheries 'hotspots' to infer threat from fisheries interaction to this population, for animals employing both strategies. Our analysis revealed repeated use of coincident oceanic habitat, over multiple seasons, by all smaller loggerhead turtles, whilst larger neritic foraging turtles occupied continental shelf waters. Modelled habitat niches were spatially distinct, and under the influence of predicted sea surface temperature rises, there was further spatial divergence of suitable habitats. Analysis of fisheries catch data highlighted that the observed and modelled habitats for oceanic and neritic loggerhead turtles could extensively interact with intensive fisheries activity within oceanic and continental shelf waters of northwest Africa. We suggest that the development and enforcement of sustainable management strategies, specifically multi-national fisheries policy, may begin to address some of these issues; however, these must be flexible and adaptive to accommodate potential range shift for this species.

Basking sharks Cetorhinus maximus have undergone widespread historic exploitation 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 individual 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 seasonality of basking shark sightings, which were at their greatest during the northeast Atlantic summer (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 atmosphere-ocean 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 following systematic harvesting in the 20th century. © Inter-Research 2012.