Paolo Casale

• PhD
• Professor (Associate) at University of Pisa

Podcast of paper published in PNAS Optimization of swim depth across diverse taxa during horizontal travel | PNAS

Semiaquatic taxa, including humans, often swim at the air–water interface where they waste energy generating surface waves. For fully marine animals however, theory predicts the most cost-efficient depth-use pattern for migrating, air-breathing species that do not feed in transit is to travel at around 2 to 3 times the depth of their body diameter,...

Interaction with fishing gears represents the main anthropogenic threat at sea for sea turtles worldwide, and identifying the hotspots of turtle bycatch is a priority knowledge gap. Turtle stranding data represent a source of information about mortality areas at sea that are not fully exploited. This study aims to infer turtle mortality areas of tu...

Knowledge of the distribution and density of marine species is key to understanding habitat use and interactions with human activities. Yet such information for sea turtles remains scarce, especially at foraging areas, where low turtle density represents an additional challenge in comparison to turtle aggregations at coastal breeding areas. Aerial...

Sea turtles spend the majority of their lives at foraging grounds. These areas are important for population persistence but generally occur in coastal habitats, which are under increasing human pressure. Identifying key foraging areas is therefore an important step to understanding critical sea turtle habitats, and therefore their threats. Isotope...

Using stable isotope analysis of carbon and nitrogen of turtle tissues and putative prey items, we investigated the diet of immature green turtles and hawksbill turtles foraging in the lagoon of Aldabra Atoll, a relatively undisturbed atoll in the southern Seychelles. Aldabra offers a unique environment for understanding sea turtle ecology. Green t...

Understanding natural movement patterns and ecological roles of marine megafauna is a research priority best studied in areas with minimal human impact. The spatial distribution patterns specifically for immature turtles at foraging grounds have been highlighted as a research gap for effective management and conservation strategies for sea turtle p...

Delineating spatial boundaries that accurately encompass complex, often cryptic, life histories of highly migratory marine megafauna can be a significant conservation challenge. For example, marine turtles range across vast ocean basins and coastal areas, thus complicating the evaluation of relative impacts of multiple overlapping threats and the c...

Assessing the linkage between breeding and non-breeding areas has important implications for understanding the fundamental biology of and conserving animal species. This is a challenging task for marine species, and in sea turtles a combination of stable isotope analysis (SIA) and satellite telemetry has been increasingly used. The Northwest Atlant...

Investigating biological aspects of migratory marine animals like sea turtles is challenging. The Adriatic Sea is a key Mediter-ranean foraging ground for loggerhead turtles, yet certain feeding behaviors remain poorly known, including winter feeding and foraging within the neritic area of the Gulf of Manfredonia. With high fishing effort, this are...

Assessing abundance and monitoring ecology and population trends are of critical importance for animal species of conservation concern. For sea turtles, annual nest counts represent the most common method of estimating population size. However, to develop a better understanding of population trends, these data need to be complemented by other repro...

The Adriatic Sea is one of the main foraging areas for marine turtles of the Mediterranean Sea, but the specific high-use sites are poorly known, due to the scarceness of satellite tracking data available for juvenile turtles frequenting the area. In the present study, we tracked 8 juvenile and adult loggerhead turtles (Caretta caretta) that were r...

Changes in marine ecosystems from human stressors, and concerns over how species will respond to these changes have emphasized the importance of understanding and monitoring crucial demographic parameters for population models. Long-lived, migratory, marine vertebrates such as sea turtles are particularly vulnerable to changes. Life-history paramet...

In sea turtles, somatic growth rates and Age at Sexual Maturity (ASM) are important parameters for investigating population dynamics. Moreover, ASM informs on the time lag needed to observe the effects of past environmental variables, threats and conservation measures acting at nesting beaches on future numbers of clutches or nesting females, that...

Assessing sea turtle movements and connectivity among different areas is pivotal to understanding their biology and implementing efficient conservation actions. In the Adriatic Sea, one of the most important sea turtle foraging areas in the Mediterranean, a total of 311 capture–mark–recapture (CMR) records (mostly bycatch) from 294 loggerhead turtl...

Abundance is a key parameter for characterizing animal populations of conservation concern. In sea turtles, annual clutch counts represent the most common population index. When the number of annual nesting females (ANF) is sought, clutch frequency (CF; average number of clutches laid per female) is used as a conversion factor. Here we assess the p...

Fisheries bycatch is the primary threat to sea turtles worldwide. Different methods are applied for bycatch reduction, from technological innovations and changes in fishing practices to reduction of fishing effort by spatio-temporal closures and banning some fisheries. All these approaches involve substantial costs and different levels of acceptanc...

Environmental policies, including the European Marine Strategy Framework Directive (MSFD), generally rely on the measurement of indicators to assess the good environmental status (GES) and ensure the protection of marine ecosystems. However, depending on available scientific knowledge and monitoring programs in place, quantitative GES assessments a...

Identifying coastal tracts suitable for sea turtle reproduction is crucial for sea turtle conservation in a context of fast coastal development and climate change. In contrast to nesting aggregations, diffuse nesting is elusive and assessing nesting levels is challenging. A total of 323 nesting events by the loggerhead sea turtle Caretta caretta ha...

Studying the impact of bycatch on marine megafauna, including sea turtles, is challenging for a variety of technical and biological reasons. The Mediterranean Sea has among the highest levels of turtle bycatch globally, notably of the loggerhead sea turtle ( Caretta caretta ), and bottom trawling represents a particularly relevant threat. Bottom tr...

Aim Understanding the spatial ecology of animal movements is a critical element in conserving long‐lived, highly mobile marine species. Analyzing networks developed from movements of six sea turtle species reveals marine connectivity and can help prioritize conservation efforts. Location Global. Methods We collated telemetry data from 1235 indivi...

Satellite tracking studies have identified some of the migratory corridors and foraging sites of Mediterranean loggerhead sea turtle ( Caretta caretta ) rookeries over the past few decades. However, due to a lack of information for breeding rookeries in Libya and Turkey, our understanding of the distribution and connectivity of adult loggerheads is...

The conservation and management of endangered species, including sea turtles, require consistent long-term monitoring of productivity (e.g., number of hatchlings emerged per nest, per female, per nesting site, per population). In sea turtle species, some of the relevant data are obtained by estimating the number of hatched eggs from fragments found...

The homing journeys of nine loggerhead turtles translocated from their nesting beach to offshore release sites, were reconstructed through Argos and GPS telemetry while their water-related orientation was simultaneously recorded at high temporal resolution by multi-sensor data loggers featuring a three-axis magnetic sensor. All turtles managed to r...

Bycatch is one of the key threats to juvenile marine turtles in the Mediterranean Sea. As fishing methods are regional or habitat specific, the susceptibility of marine turtles may differ according to inter- and intra-population variations in foraging ecology. An understanding of these variations is necessary to assess bycatch susceptibility and to...

ABSTRACT: Estimating population abundance is key for species of conservation concern. This is particularly challenging for marine animals, like sea turtles, with ocean-scale distribution and migratory nature. However, sea turtles lay clutches on land where they can be easily counted; thus, clutch number has always been the most common index of popu...

Understanding population status and trends is important for developing and evaluating management and conservation actions for threatened species. Monitoring population status of marine organisms is especially challenging. Because sea turtles come ashore to lay their eggs and nests are easily counted, these counts are commonly used as an index of ab...

Capture-mark-recapture studies rely on the identification of individuals through time, using markers or tags, which are assumed to be retained. This assumption, however, may be violated, having implications for population models. In sea turtles, individual identification is typically based on external flipper tags, which can be combined with intern...

In the Mediterranean Sea, bottom trawl, bottom longline and set nets are the fishing gears with the highest impact on marine turtle populations. These demersal gear types are characterised by a variety of métiers (fishing operations targeting a specific assemblage of species, using specific gear, during a precise period of the year and/ or within a...

Spatio‐temporal distribution is fundamental information for species of conservation concern, like sea turtles, that are threatened by anthropogenic activities at sea such as fishing. While coarse‐scale distribution information is available for several sea turtle populations, fine‐scale distribution informing on hot‐spot areas for spatial management...

Range of occurrence and abundance is a fundamental information that describes an animal population and is particularly important for species of conservation concern such as sea turtles. Although sea turtles lay clutches on land, which helps identifying breeding aggregations, the current knowledge on the distribution of these animals is far from bei...

There have been efforts around the globe to track individuals of many marine species and assess their movements and distribution, with the putative goal of supporting their conservation and management. Determining whether, and how, tracking data have been successfully applied to address real-world conservation issues is, however, difficult. Here, w...

Estimating population abundance is key for species of conservation concern. This is particularly challenging for marine animals, like sea turtles, with ocean-scale distribution and migratory nature. However, sea turtles lay clutches on land where they can be easily counted; thus, clutch number has always been the most common index of population abu...

Sea turtle research has received substantial focus worldwide. However, research on the immature life stages of sea turtles is still relatively limited. The latter is of particular importance, given that a large proportion of sea turtle populations comprises immature individuals. We set out to identify knowledge gaps in immature sea turtle research,...

The available information regarding the 2 sea turtle species breeding in the Mediter-ranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic...

The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic...

ABSTRACT: The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anth...

Migration is one of several marine vertebrate traits increasingly affected by human encroachment. The Adriatic Sea is an important foraging and wintering site for loggerhead turtles (Caretta caretta), and one of the Mediterranean regions where they are most heavily impacted, particularly by fisheries bycatch. Conservation measures concern foraging...

Gabon hosts nesting grounds for several sea turtle species, including the world’s largest rookery for the leatherback turtle (Dermochelys coriacea), Africa’s largest rookery for the olive ridley turtle (Lepidochelys olivacea) and smaller aggregations of the hawksbill turtle (Eretmochelys imbricata) and green turtle (Chelonia mydas). To assess the l...

We investigate for the first time allometric vs. non-allometric shape variation in sea turtles through a geometric morphometrics approach. Five body parts (carapace, plastron, top and lateral sides of the head, dorsal side of front flippers) were considered in a sample of 58 loggerhead turtles (Caretta caretta) collected in the waters around Lamped...

A detailed knowledge of sea turtle distribution in relation to anthropogenic threats is key to inform conservation measures. We satellite tracked five loggerhead turtles incidentally caught in the Gulf of Manfredonia, where a high turtle occurrence and high by-catch levels have been recently reported. Turtles were tracked for a period ranging from...

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...

As in many other species, tagging has been routinely conducted for decades in over a hundred sea turtle capture-mark-recapture (CMR) programs worldwide. Tag loss is a key limiting factor because it violates the main assumption in CMR models; however, very few estimates of tag loss exist, and we provide here a review. No published estimations of tag...

Mediterranean populations of loggerhead Caretta caretta and green sea turtles Chelonia mydas are subject to several anthropogenic threats, with documented mortality from incidental capture in fishing gear. However, how such mortalities actually affect the populations is uncertain without an estimate of population size. We derived a theoretical demo...

Understanding the at-sea spatial behaviour of sea turtles is a priority for their conservation. In the present paper, the current information on the distribution and movement patterns of the two species breeding in the Mediterranean, the loggerhead and the green turtle, is reviewed, focusing mainly on the 195 published routes of satellite-tracked t...

Sea turtles show temperature-dependent sex determination (TSD) and information on sex ratios at different life stages is necessary both for population dynamics models for conservation and to shed light on the possible adaptive value of TSD. Adults represent the less abundant class of sea turtle populations and adult sex ratios at foraging grounds a...

One of the major gaps in the knowledge of sea turtle population dynamics is survival probability, in particular of juveniles, which represent the bulk of the population and whose survival has the greatest effect on population growth. One of the major global threats to sea turtles is incidental bycatch, although not all animals die in the process. T...

Identifying highly frequented areas is a priority for sea turtle conservation, and the distribution of young individuals in open waters represents a major knowledge gap due to methodological biases. The drift of hatchlings from 38 loggerhead Caretta caretta and 10 green Chelonia mydas turtle nesting sites in the Mediterranean was simulated for the...

In migratory species female‐ and male‐mediated gene flow are important for defining relevant Management Units, and for evaluating connectivity between these and their respective foraging grounds. The stock composition at five Mediterranean foraging areas was investigated by analysing variation in the mitochondrial D‐loop and six microsatellite loci...

Loggerhead sea turtles (Caretta caretta) frequent very distant areas during their life stages, and information about migratory routes and geographical range is key for planning their conservation. Here we report on the first direct evidence of a loggerhead turtle migrating from the eastern Mediterranean to the North American coast. A juvenile of 57...

Ten adult male loggerhead sea turtles, captured by trawlers or dip nets, were satellite-tracked from a neritic foraging ground in the Mediterranean in order to investigate adult spatio-temporal distribution and breeding migration. Five individuals migrated to potential breeding sites in Libya and one to Greece. The results complement previous studi...

Information on sea turtle population trends is fundamental to assess the population status and the effects of conservation measures, and is considered a priority for sea turtle conservation. To provide insights on trends at sea, we compared by-catch data from long-liners fishing in the Gulf of Taranto in 2 periods: 1978-1979 and 1998-2003. A total...

We report seven nesting events by loggerhead sea turtles in Sicily (Italy) in 2011. In comparison to past records, this number is relatively high and may be at least in part due to an awareness campaign carried out in 2011 to solicit such reports. This suggests that Sicily may host a much higher nesting activity than previously thought and higher m...

Knowledge about migratory routes and highly frequented areas is a priority for sea turtle conservation, but the movement patterns of juveniles frequenting the Adriatic have not been investigated yet, although juveniles represent the bulk of populations. We tracked by satellite six juvenile and one adult female loggerhead from the north Adriatic. Th...

The Adriatic Sea is an important foraging area for the loggerhead sea turtle, Caretta caretta, but neritic habitats for this species along the Italian coast were identified in the northern shallow area only. The Gulf of Manfredonia is a relatively wide shallow area in the south-west Adriatic and its features and preliminary information make it a po...

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 she...

The association patterns and ecology of sea turtle epibionts, and especially obligate epibionts, are still poorly known. Epibiont communities were investigated in the central Mediterranean Sea in relation to the host habitat and seven species of barnacles, three amphipods, one crab, and one tanaid were found on 117 loggerhead sea turtles, Caretta c...

Categories in which RMUs for each species occurred (including critical data needs RMUs). Categories: HR-HT = High risk-High threats; HR-LT = High risk-Low threats; LR-LT = Low risk-Low threats; LR-HT = Low risk-High threats. (DOCX)

Paired risk and threats scores for RMUs of each marine turtle species. (A) loggerheads (Caretta caretta), (B) green turtles (Chelonia mydas), (C) leatherbacks (Dermochelys coriacea, (D) hawskbills (Eretmochelys imbricata), (E) olive ridleys (Lepidochelys olivacea), (F) Kemp's ridleys (Lepidochelys kempii) and flatbacks (Natator depressus). Vertical...

Scoring system for population size criterion in risk matrix. Numbers are average annual nesting females for the most recent survey data available. (DOCX)

List of Regional Management Unit (RMU) codes used in Fig. 1. Species: Caretta caretta, loggerhead; Chelonia mydas, green turtle; Dermochelys coriacea, leatherback; Eretmochelys imbricata, hawksbill; Lepidochelys kempii, Kemp's ridley; Lepidochelys olivacea, olive ridley; Natator depressus, flatback. (DOCX)

Bibliography of literature used to score risk and threats criteria. (PDF)

Areas of Competence for Regional Fishery Bodies (RFB) with a management mandate. RFB acronyms: CCAMLR: Commission on the Conservation of Antarctic Marine Living Resources; CCBSP: Convention on the Conservation and Management of Pollock Resources in the Central Bering Sea; CCSBT: Commission for the Conservation of Southern Bluefin Tuna; GFCM: Genera...

Complete dataset used to score all criteria in Risk and Threats matrices, as well as data uncertainty scores. (XLS)

Complete list of SWOT – The State of the World's Sea Turtles data providers. (XLS)

Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widel...

Aerial line transect surveys, totalling 16590 km, were performed in winter and summer 2009 in the Pelagos Sanctuary, NW Mediterranean. A total of 207 loggerhead sea turtles were sighted, with only 9 sightings during the winter. In this season average raw ‘surface’ density (i.e. animals at or near the surface) was 0.002 turtles km–2, and on the basi...

Sea turtle by-catch data in the Mediterranean were reviewed and analysed with fishing effort. The results indicate over 132 000 captures per year, with probably over 44 000 incidental deaths per year, while many others are killed intentionally. Small vessels using set net, demersal longline or pelagic longline represent most of the Mediterranean fl...

Skeletochronology was applied to humerus bones to assess the age and growth rates of loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Fifty-five dead turtles with curved carapace lengths (CCL) ranging from 24 to 86.5 cm were collected from the central Mediterranean. Sections of humeri were histologically processed to analyze annua...

It is widely accepted that the age at sexual maturity of sea turtles is a critical parameter for studying population dynamics and persistence. Estimates of the age at maturity for such longlived species are derived using somatic growth models, which are still lacking for several regions of the world. In the present study, the growth rate of the log...

Turtle trade in the fish markets of Alexandria was reported up to the late 1990s, motivating conservation initiatives and enforcement of legal protection. To assess the current trade and bycatch levels in Alexandria and other ports we carried out an interview survey of 445 people in 2007, mostly fishermen and fishmongers, in 15 coastal cities and f...

Summary of Regional Management Units (RMUs) for marine turtles worldwide, including number of nesting sites and genetic stocks contained within each RMU. (DOC)

Metadata associated with each layer synthesized to generate Regional Management Units. (XLS)

Complete list of SWOT – The State of the World's Sea Turtles data providers. (XLS)

Background: Resolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. There...

Spatio‐temporal distribution and anthropogenic mortality factors were investigated in loggerhead turtles ( Caretta caretta ) found stranded or floating in the waters around Italy. A total of 5938 records for the period 1980–2008 were analysed concerning loggerhead turtles measuring from 3.8 to 97 cm curved carapace length (mean: 48.3 cm). Results h...

Over the past 3 decades, the status of sea turtles and the need for their protection to aid population recovery have increasingly captured the interest of government agencies, non-govern- mental organisations (NGOs) and the general public worldwide. This interest has been matched by increased research attention, focusing on a wide variety of topics...

Growth rates of the juvenile phase of loggerhead turtles (Caretta caretta) were estimated for the first time in the Mediterranean Sea from capture-mark-recapture records. Thirty-eight turtles were released from Italian coasts and re-encountered after 1.0-10.9 years in the period 1986-2007. Their mean CCL (curved carapace length) ranged from 32.5 to...

Growth rate is a fundamental parameter in understanding sea turtle population dynamics and is also important for the conservation of these threatened species. It can be influenced by both environmental and genetic factors, and thus it can vary according to the area. Growth rates and age at size of loggerhead turtles (Caretta caretta) are estimated...

In the central Mediterranean Sea, gut contents and feces of 95 turtles captured by bottom trawlers and pelagic longliners fishing in neritic and oceanic areas, respectively, were examined. Benthic prey were more abundant than pelagic, a probable bias due to the higher digestibility of the latter. Animal and plant taxa belonging to 12 Phyla and 20 C...

The wide north African continental shelf in the central Mediterranean is known to be one of the few important areas in the basin for loggerhead turtles in the neritic stage. In order to assess the origin of these turtles, sequences of the mtDNA control region were obtained from 70 turtles caught by bottom trawlers in the area, and compared with kno...

rome 2 'tor vergata', via della ricerca scientifica, 00133 roma, italy sUMMarY: the wide north african continental shelf in the central Mediterranean is known to be one of the few impor-tant areas in the basin for loggerhead turtles in the neritic stage. in order to assess the origin of these turtles, sequences of the mtDna control region were obta...

Drifting longlines are considered a major threat to endangered sea turtle populations worldwide. However, for a number of reasons, the mortality rate of captured turtles is not known with any certainty. Information on 409 loggerhead turtles ( Caretta caretta ), collected during the day‐to‐day activities of a turtle rescue centre in Lampedusa island...