Anthropogenic food patches in the marine environment, such as aquaculture farms and active trawlers, may impact on the behavior of marine mammals through modification of habitats, changes in predation pressure, or alterations in food distribution, availability, and predictability, affecting related social interactions and population demographics. This study examined patterns of association of a population of common bottlenose dolphins (Tursiops truncatus) around Lampedusa Island (Italy) during 1996-2006 and tested the hypothesis that the trawl fishery and the presence of an aquaculture farm could affect such patterns. Here, we used measures of association between pairs of individuals to assess this impact on social unit composition/cohesion and some analytical techniques to describe the structure of dolphin social networks and temporal stability of associations. Association information for 71 regularly sighted individuals was obtained from photo-identification surveys within groups observed or not at ''feeding stations.'' We found association patterns between dolphins were nonrandom. The Lampedusa population seems to be arranged into 6 clusters and organized in communities composed of animals that were either never seen in association with feeding stations (N individuals) or those that are (Y individuals), although mixed assemblages were also recorded. Both communities showed long-term preferred companions, with different degrees of social cohesion-as resulted by network measures and temporal analysis. Delineating community structure at Lampedusa Island has offered basic information for further investigations in the area, also providing novel evidences on how disparities in association patterns between bottlenose dolphin individuals may have resulted from a combination of ecological and anthropogenic factors.

Sources of data other than those derived from conventional research protocols may contribute valuable information to fill gaps in knowledge about cetacean occurrences and diversity in a given area and help address conservation issues. The performance of a method to examine cetacean communities based on presence records systematically derived from shared photographs and videos posted by boaters and maritime operators on social media (e.g. YouTube and Facebook) combined with patchy distributed visual/acoustic data collected by researchers has been evaluated. Records (N = 1,274) gathered over a 10‐year period (2008–2017) have been used to obtain insights into species' presence and habitat selection in a scattered study area of the central Mediterranean Sea (Italy). The effectiveness of the method, practical and theoretical advantages, limitations, and challenges of using data originated from social media for research and conservation purposes are discussed. Seven out of the eight cetacean species regularly residing in the Mediterranean have been reported in the area, with different relative densities. Maximum entropy modelling techniques have been applied to the datasets derived from (a) social media, (b) research surveys, and (c) the combination of the two, using six fixed variables as proxies for cetacean presence. Distance from the coast and depth emerged as the main variables predicting encounters, with specificities related to the ecology of the species. The approach was reliable enough to obtain broad‐scale, baseline information on cetacean communities in the region, on the basis of which initial conservation recommendations and future research programmes can be proposed. With the increasing need for studying whale and dolphin population ecology coming from national/international directives, support from citizens to aid research may act as a practical, inexpensive solution to gathering extensive spatial–temporal data for regional‐scale monitoring and for the development of management priorities.

Periodic assessments of population status and trends to detect natural influences and human effects on coastal dolphin are often limited by lack of baseline information. Here, we investigated for the first time the site-fidelity patterns and estimated the population size of bottlenose dolphins (Tursiops truncatus) at the Tiber River estuary (central Mediterranean, Tyrrhenian Sea, Rome, Italy) between 2017 and 2020. We used photo-identification data and site-fidelity metrics to study the tendency of dolphins to remain in, or return to, the study area, and capture–recapture models to estimate the population abundance. In all, 347 unique individuals were identified. The hierarchical cluster analysis highlighted 3 clusters, labeled resident (individuals encountered at least five times, in three different months, over three distinct years; n = 42), part-time (individuals encountered at least on two occasions in a month, in at least two different years; n = 73), and transient (individuals encountered on more than one occasion, in more than 1 month, none of them in more than 1 year; n = 232), each characterized by site-fidelity metrics. Open POPAN modeling estimated a population size of 529 individuals (95% CI: 456–614), showing that the Capitoline (Roman) coastal area and nearby regions surrounding the Tiber River estuary represent an important, suitable habitat for bottlenose dolphins, despite their proximity to one of the major urban centers in the world (the city of Rome). Given the high number of individuals in the area and the presence of resident individuals with strong site fidelity, we suggest that conservation plans should not be focused only close to the Tiber River mouths but extended to cover a broader scale of area.

The first record of killer whale (Orcinus orca) predation on false killer whales (Pseudorca crassidens) is reported here. On 25 March 2010, a group of 50 to 60 false killer whales, including approximately 15 calves and accompanied by three to five bottlenose dolphins (Tursiops sp.), were sighted in the Bay of Islands, New Zealand. Within 30 min, they were approached by a group of approximately eight killer whales. Five false killer whales were attacked, with at least three rammed from below, forcing them out of the water. After 29 min, the killer whales were milling at the surface and feeding on the carcass of a false killer whale calf, possibly the only individual killed. The killer whales had prolific fresh and healed oval wounds, which were attributed to cookie cutter shark (Isistius sp.) bites.

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.

ABSTRACT1. Boat surveys aimed at studying sperm whales in the Tyrrhenian Sea were conducted between 2002 and 2011. During 768 daily surveys, a total effort of 32 602 km was achieved within an area of 8800 km 2 resulting in 92 encounters with 229 sperm whale individuals. 2. Average encounter rates of sperm whales was 0.5 groups per 100 km 2 , with a higher concentration in the vicinity of the submarine canyon of Cuma, confirming the importance for the species of this small hotspot in the Mediterranean Sea. 3. Encounter rates increased with increasing distance from the coast. It is possible that the intense boat traffic and anthropogenic disturbance in the area may be moving animals away from the coast leading to habitat loss.4. The species-habitat relationship documented in this study has implications for conservation.