ABSTRACT1. As part of a project to identify marine protected areas (MPAs) in Spanish Mediterranean waters, habitat preference models were developed using 11 years of survey data to provide predictions of relative density for cetacean species occurring off southern Spain.2. Models for bottlenose, striped and common dolphin described, firstly, probability of occurrence (using GLMs) and, secondly, group size (using linear models) as predicted by habitat type defined by a range of physical and oceanographic covariates. Models for Risso's dolphin, long-finned pilot, sperm and beaked whales used only the first stage because of data limitations.3. Model results were used to define the boundaries of three proposed Special Areas of Conservation (SAC) (under the EU Habitats Directive) and one proposed Specially Protected Area of Mediterranean Importance (SPAMI) (under the Barcelona Convention).4. The study illustrates the value of habitat preference modelling as a tool to help identify potential MPAs. The analyses incorporate environmental data in a spatial prediction that is an improvement over simpler descriptions of animal occurrence. Contiguous areas covering a specified proportion of relative abundance can readily be defined. Areas with apparently good habitat but few observations can be identified for future research or monitoring programmes.5. Models can be refitted as new observations and additional environmental data become available, allowing changes in habitat preference to be investigated and monitoring how well MPAs are likely to be affording protection.6. The study represents an important contribution to the implementation of the Habitats Directive by the Spanish government by providing a robust scientific basis for the definition of SAC and providing results to inform conservation objectives and management plans for these areas. The results identified areas that are important for a number of cetacean species, thus illustrating the potential for MPAs to improve cetacean conservation generally in the Alboran Sea, a
Little is known about the long‐finned pilot whale's population size, structure, distribution, and dynamics in the Western Mediterranean basin. The research region covered since 1992 in southeast Spain, at the edge of the Alboran Sea, is considered an important oceanographic transition zone between the Mediterranean and the Atlantic Ocean. The research ship Toftevaag carried out surveys covering a total of 10,173 nmi (18,840 km) from April to September each year, 1992‐1997, all years pooled. Effort for ten‐by‐ten‐mile quadrants was stratified by depth and sea state to ascertain encounter rates. Tracking was used together with photo‐identification of animals to analyze home range of groups. Behavior was recorded ad libitum, and underwater video taping was used to analyze specific behavior patterns. One hundred and nine sightings of pilot whales were made. The average group size was 41.4 ± 58.4, ranging from 1 to 350. The average depth at encounters was 848.7 ± 281.2 m ranging from 300 to 1,800 m. Compatison of results for encounter rate and group size with those for other Mediterranean regions, together with site fidelity shown by photo‐identification and observations of reproductive behavior, reflect the importance of the Alboran Sea to the species in the Mediterranean.
Bycatch of endangered loggerhead turtles in longline fisheries results in high rates of post-release mortality that may negatively impact populations. The factors contributing to post-release mortality have not been well studied, but traumatic injuries and physiological disturbances experienced as a result of capture are thought to play a role. The goal of our study was to gauge the physiological status of loggerhead turtles immediately upon removal from longline gear in order to refine our understanding of the impacts of capture and the potential for post-release mortality. We analysed blood samples collected from longline-and hand-captured loggerhead turtles, and discovered that capture in longline gear results in blood loss, induction of the systemic stress response, and a moderate increase in lactate. The method by which turtles are landed and released, particularly if released with the hook or line still attached, may exacerbate stress and lead to chronic injuries, sublethal effects or delayed mortality. Our study is the first, to the best of our knowledge, to document the physiological impacts of capture in longline gear, and our findings underscore the importance of best practices gear removal to promote post-release survival in longline-captured turtles.
Loggerhead turtles are a globally vulnerable species of marine turtle. Broad-scale patterns of distribution and abundance can provide regional managers a tool to effectively conserve and manage this species at basin and sub-basin scales. In this study, combined aerial and shipboard line transect survey data collected between 2003 and 2018 were used to estimate distribution and abundance throughout the Mediterranean Sea. Approximately 230,000 linear kilometers of survey effort, from seven different surveying organizations were incorporated into a generalized additive model to relate loggerhead density on survey segments to environmental conditions. Two spatial density models estimating loggerhead density, abundance, and distribution were generated – one a long-term annual average covering 2003-2018 and another covering the summer of 2018, when a basin-wide aerial survey, the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area Survey Initiative, was performed. Both models were adjusted for availability bias using dive data from loggerhead turtles tagged with time depth recorders. Mean abundance for the long-term average model was estimated as 1,201,845 (CV=0.22). The summer 2018 abundance estimate was 789,244 turtles and covered a smaller area than the long-term average. These estimates represent the first basin-wide estimates of abundance for loggerhead turtles in the Mediterranean not based on demographic models. Both models predicted similar distributions, with higher abundance predicted in the northern Adriatic Sea, central Mediterranean basin, Tyrrhenian Sea, and south of the Balearic Islands. Lower densities were predicted in the eastern Mediterranean Sea and the Aegean Sea. The highest density areas generally did not coincide with previously established adult loggerhead turtle foraging areas, which are typically neritic, indicating the models are predominantly predicting oceanic distributions, where most of the survey effort occurred. Juvenile loggerhead turtles are predominantly oceanic and comprise most of the population, but care must be taken when using these models as they may not accurately predict distribution of neritic foraging areas, where subadult and adult loggerheads can often be found. Despite this limitation, these models represent a major step forward for conservation planning and understanding basin-wide distribution and abundance patterns of this species.
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 are not always feasible. This is specifically the case for marine turtle species, which are listed under the Biodiversity Descriptor of the MSFD. Relying on an expert consultation, the goal of this study was to develop indicators and a common assessment approach to be employed by European Union Member States to evaluate the status of marine turtle populations in the frame of the MSFD. A dedicated international expert group was created to explore and test potential assessment approaches, in coherence with other environmental policies (i.e. Habitats Directive, OSPAR and Barcelona Conventions). Following a series of workshops, the group provided recommendations for the GES assessment of marine turtles. In particular, indicators and assessment methods were defined, setting a solid basis for future MSFD assessments. Although knowledge gaps remain, data requirements identified in this study will guide future data collection initiatives and inform monitoring programs implemented by EU Member States. Overall this study highlights the value of international collaboration for the conservation of vulnerable species, such as marine turtles.
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