1. The recent decline in the Mediterranean population of short‐beaked common dolphins Delphinus  delphis  has  been  the  subject of scientific controversy  and  political  indifference. Research on these animals has been very limited and there has been no large‐scale, systematic effort to assess and monitor their abundance and distribution. The consequent lack of data has prevented a good understanding of historical and ongoing trends. 2. Nonetheless, literature and osteological collections confirm that common dolphins were widespread and abundant in much of the Mediterranean Sea until the late 1960s and that their decline occurred relatively quickly. Today, common dolphins remain relatively abundant only in the westernmost portion of the basin (Alboràn Sea), with sparse records off Algeria and Tunisia, concentrations around the Maltese islands and in parts of the Aegean Sea, and relict groups in the south‐eastern Tyrrhenian and eastern Ionian Seas. Otherwise, these dolphins are rare in, or completely absent from, Mediterranean areas where information is available. 3. Circumstantial evidence and qualitative judgements by the authors suggest that the following factors may have contributed to the decline of common dolphins: reduced availability of prey caused by overfishing and habitat degradation; contamination by xenobiotic chemicals resulting in immunosuppression and reproductive impairment; environmental changes such as increased water temperatures affecting ecosystem dynamics; and incidental mortality in fishing gear, especially gillnets. The cumulative importance of these factors is poorly understood, and as a result, few conservation measures have been implemented. 4. This paper reviews current knowledge and suggests priorities for action aimed at identifying and mitigating the main threats to common dolphins in the Mediterranean, with the ultimate goal of restoring the species’ favourable conservation status in the region.

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The identification of significant habitats for highly mobile marine vertebrates is essential for their conservation. Evidence is often difficult to obtain for deep‐diving species such as sperm whales (Physeter macrocephalus), where standard visual survey methods are not sufficient to detect the species. Sperm whales rely on sound for most of their activities, so acoustics is a crucial tool to locate them in the environment and collect information about their daily life. We used a maximum entropy (MaxEnt) modeling approach to predict potential habitats for sperm whales during 2007–2015 in an area of the Mediterranean Sea (characterized by submarine canyon systems) where sperm whale singletons, social units of females and calves, and clusters with immature males, were regularly encountered in sympatry. Models to test species’ distribution and the potential differences between groups of varying composition and life stages were based on 3 independent variables (depth, slope, and Euclidean distance from the nearest coast) and a combination of presence‐only visual and acoustic data from boat‐based surveys. One variable (depth) was the strongest predictor in all encounters (pooled data) and clusters, whereas distance from coast and slope best predicted encounters with singletons and social units, respectively. The model predicted suitable locations in areas that were well‐known sperm whale habitat and in new regions of previously overlooked habitat, which possibly represent key areas for this endangered species in the Mediterranean. This study highlights that consideration should be taken regarding type of social aggregation when using modeling techniques for generating suitable habitat maps for conservation purposes. © 2018 The Wildlife Society.

1. Preservation of endangered species is now recognized as a relevant component of regional and global conservation actions achieved through the maintenance of the remaining populations in a favourable conservation status. The Mediterranean common dolphin (Delphinus delphis) is listed as an Endangered subpopulation in the International Union for Conservation of Nature Red List, with declining numbers in some of the areas where it has been studied for numerous years. Prey depletion, fisheries bycatch, pollution, health risks, and climate change are among the recognized threats that the species is facing in the region.2. The existing national, regional, and international legislation pertinent to Mediterranean countries should aid greater science-policy-management integration and support innovative research and monitoring towards effective conservation. The challenges inherent in studying the pelagic D. delphis should not preclude the use of long-term, year-round, multiplatform surveys, side by side with the latest molecular tools, which aid our understanding of its populations' genetic diversity, resistance to diseases, and resilience in a semi-enclosed fast-changing sea.3. Addressing the multiplicity of problems confronting the species requires collaborative effort at all levels to share and merge resources, data, and expertise more efficiently. In this review, we provide an overview of the current knowledge on the Mediterranean common dolphin, the main threats, and knowledge gaps that are priorities for addressing its conservation, while providing clear recommendations for effectively safeguarding the species and its habitat at both local and regional levels.

ABSTRACT1. The Mediterranean sperm whale sub-population is considered 'Endangered' by both ACCOBAMS and the IUCN. Conservation policies require protected species populations to be monitored, but the distribution and movements of sperm whales across the Mediterranean Sea are still poorly understood.2. To provide insight into sperm whale movements, the photo-identification catalogue from the Strait of Gibraltar was compared with seven other collections: (a) the North Atlantic and Mediterranean Sperm Whale Catalogue (NAMSC), and with photo-identification catalogues from (b) the Alboran Sea, Spain, (c) the Balearic Islands, Spain, (d) the Corso-Provençal Basin, France, (e) the Western Ligurian Sea, Italy, (f) the Tyrrhenian Sea, Italy and (g) the Hellenic Trench, Greece.3. Of 47 sperm whales identified in the Strait of Gibraltar between 1999 and 2011 a total of 15 animals (32%) were photographically recaptured in other sectors of the western Mediterranean Sea in different years. None of the Strait of Gibraltar sperm whales were resighted in Atlantic waters or in the eastern Mediterranean basin.4. These results indicate long-range movements of the species throughout the whole western Mediterranean Sea, with a maximum straight-line distance of about 1600 km. The absence of any photographic recaptures between the Mediterranean Sea and the North Atlantic Ocean supports the genetic evidence of an isolated sub-population within the Mediterranean Sea.5. Long-term photo-identification efforts and data sharing between institutions should be further encouraged to provide basic information necessary for the implementation of effective sperm whale conservation measures in the whole basin.