The Mediterranean Sea provides habitat for a diverse assemblage of marine species, including 14 resident species of cetacean, 3 species of turtle and the Mediterranean monk seal. Surrounded by densely populated coastlines, marine megafauna in the region are exposed to multiple anthropogenic threats. Alongside a growing awareness of these threats, and national, EU and international legal frameworks to conserve these species and their habitats, there is increasing pressure to exploit hydrocarbon deposits in the region. The exploration and extraction of oil and gas require a precautionary approach to allow effective protection and, where possible, mitigation of impacts on marine life. This paper examines contentious case studies from the Mediterranean where best practice to mitigate harmful effects has not been followed. Even where these failings are not unequivocally in breach of legal obligations, they demonstrate unethical conduct. Recommendations to improve mitigation are presented, including the need to (1) adequately consider the propagation of impacts into local protected areas, (2) update impact assessments (including acoustic modelling) when planned activities change significantly, (3) make documents and timings public prior to starting harmful activities, (4) demonstrate that seismic survey operators are using the lowest possible source levels and number of shots to meet objectives, (5) provide stronger incentives for industry to invest in risk reduction (including a significant increase in financial responsibility), (6) ensure regulatory authorities establish that the relevant guidelines are being followed and (7) make survey reports summarising encounters with marine megafauna publicly accessible in a timely fashion.

The Hellenic Trench hosts the highest density of endangered sperm whales in the Eastern Mediterranean Sea and is recognised as an Important Marine Mammal Area (IMMA). This population is exposed to substantial anthropogenic pressures, including vessel strikes, hydrocarbon activities and military exercises. In July 2024, a solitary adult male was equipped with a minimally invasive ARGOS satellite‐linked transmitter southwest of Kefalonia, Greece. Over 57 days, the whale ranged from the Ionian Sea through the Hellenic Trench into the southern and northeastern Aegean Sea. Movement analyses revealed extended periods of localised movements southwest of Kefalonia‐Zakynthos and later in the northeastern Aegean, indicative of potential feeding behaviour, interspersed with phases of directed travel along the Hellenic Trench and across the Cyclades toward the Dodecanese. This is the first satellite track of a male sperm whale in Greece, providing novel insights into habitat use, movement strategies, and previously undocumented transit and residency areas. These findings highlight new key areas for place‐based conservation and demonstrate the value of satellite telemetry for informing targeted management in the Eastern Mediterranean.

ABSTRACT Human‐caused injuries can have severe consequences for cetaceans, both for the well‐being of individuals and the effects at the population level. Here, we report the first case of a live fin whale in the Mediterranean Sea with completely amputated flukes, a female who suffered two separated incidents: the first one before 1996, when she lost her left lobe, and the second one, in 2019, leading to the severing of the whole tail and finally to presumed death. “Codamozza‐Fluker” was regularly sighted during summer in the North‐Western Mediterranean for 24 years. Entanglement and collision were both hypothesized as potential causes of her injuries. Without flukes, she traveled at least 7000 km across the Mediterranean, despite severe emaciation. Sighting records allowed tracking her from September 2019 to July 2020, providing rare evidence of large‐scale movements within the Mediterranean over almost a year. Her journey, which extended as far as Syria, provides the first evidence of a fin whale from the Ligurian Sea being resighted in the Eastern Basin. This introduces a new perspective on this endangered subpopulation's movement patterns, which are crucial for effective conservation measures. The case gained widespread media attention, representing a dramatic example of usually unnoticed injuries or deaths, and contributed to raising public awareness, essential for driving focused conservation efforts. Her latest accident most likely occurred within the Pelagos Sanctuary for marine mammals, highlighting the need for more effective local protection measures, and underscoring the importance of complementing area‐based conservation efforts with an ecosystem‐based approach.

To investigate the seasonal migratory behaviour of spinetail devil rays, Mobula mobular, across the Mediterranean Sea, we used satellite telemetry to track nine individuals between 2016 and 2021. The species is listed as Endangered in the IUCN’s Red List of Threatened Species and appears to be most vulnerable to fishing impacts when gathering in large assemblages. The only known targeted devil ray fishery harvests significant numbers each winter off Gaza. While broadly distributed during summer across the more productive areas of the western and central portions of the Mediterranean, most tracked rays showed an eastward movement towards eastern Levantine waters during the second half of the year. One individual, tagged off Gaza in March 2016, travelled to Spain before swimming back to the Levantine Sea one year later. Our study corroborates the notion that the species undergoes predictable basin-wide migrations across the Mediterranean Sea, favouring the Levantine waters in late winter and early spring, thanks to the subregion’s milder sea surface temperatures in that time of the year compared to the rest of the Mediterranean. Understanding the species’ seasonal movement pattern in the Mediterranean could support the implementation of robust place-based conservation measures, especially in light of unregulated fishing pressure.

The Pelagos Sanctuary for Mediterranean Marine Mammals is a designated marine protected area in the north-western Mediterranean, encompassing waters between the Côte d’Azur (France), the Ligurian and Tuscan coasts (Italy), and Monaco, extending southward to the northern coastline of Sardinia. This area hosts a diversity of cetacean species. Due to high levels of maritime traffic, the Mediterranean Sea is a global hotspot for whale-vessel collisions. The frequency of both lethal and sub-lethal collisions in the region is considerable, with a general consensus that both direct mortality and long-term population-level effects significantly hinder the recovery and persistence of whale populations.We present SEADETECT, a LIFE programme project aimed at the development of innovative technological solutions to help prevent lethal incidents between cetaceans and ships. Two complementary technical approaches with a combination of different sensors are developed to bring automatic whale awareness onboard vessels in order to avoid collisions.

The distribution of wild animals and their monitoring over large areas raises many logistical and technical difficulties that hinder the collection of observation data. The use of Geographic Information Systems (GIS) has increased significantly in recent years. QGIS, an open-source GIS software dedicated to the processing of geospatial data, enables the development of dedicated plugins for specific workflows. The open-source PelaSIG plugin has been developed in Python for QGIS 3 to facilitate and standardise the different steps before and after distance sampling surveys. It brings together a set of tools for survey preparation, automatic data checking, visualisation and presentation of survey effort and sightings to provide an adapted workflow. This plugin is currently designed to process dedicated aerial datasets collected with the SAMMOA software during marine megafauna surveys (i.e., marine mammals, seabirds, elasmobranchs, sea turtles, etc.). Here, we first describe the different tools already available, and then, we present an application with the dataset from the aerial survey of the ACCOBAMS Survey Initiative (ASI) conducted in 2018 over the Mediterranean Sea and using a multi-target protocol.

The “ACCOBAMS Survey Initiative” (ASI) is a pilot programme aimed at establishing an integrated and coordinated monitoring system for cetaceans across the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic (hereafter “ACCOBAMS”) area. Conducted in coordination with Mediterranean coastal countries, it supports the implementation of European and regional policies, in particular the EU Marine Strategy Framework Directive and the Ecosystem Approach process. In summer 2018, a synoptic survey was conducted across the Mediterranean Sea and contiguous Atlantic area, combining visual monitoring from aircrafts with visual and passive acoustic monitoring from vessels. Species density and abundance were estimated through design-based approach in a line-transect sampling framework. Based on data arising from the aerial survey only, uncorrected design-based abundance was obtained for striped (N=426,744, CV=0.13), common (N=65,359, CV=0.4), bottlenose (N=63,333, CV=0.17), and Risso´s dolphins (N=26,006, CV=0.3), Cuvier’s beaked whales (N=2,929, CV=0.4) and long-finned pilot whales (N=5,540 CV=0.4). A merged category of either striped or common dolphins resulted in 212,483 individuals (CV=0.26). Fin whales abundance of 1,749 animals (CV=0.3) was corrected for both availability and perception biases and resulted in 3,282 (CV=0.31). The ASI survey offers an overall picture of the distribution and abundance of cetaceans throughout the Mediterranean basin, providing robust estimates to be considered as a baseline for future regional systematic monitoring programmes. The ASI survey is the first step towards establishing a long-term monitoring program across the entire ACCOBAMS area, and, as such, it sets the basis for further future basin-wide monitoring efforts using systematic, shared, coordinated and comparable methods. The information gathered will further enhance knowledge on cetacean status, facilitating the development of informed conservation and mitigation measures, as well as supporting the implementation of international obligations. Furthermore, the outcomes of this survey will support both place- and threat-based conservation efforts in the ACCOBAMS area, through the identification of Important Marine Mammal Areas and Cetacean Critical Habitats. Here the results of the ASI survey are presented and discussed alongside proposed management and conservation actions aimed at ensuring the persistence of cetacean populations in the region.

Annex A: List of Participants Annex B: Agenda Annex C: List of Documents How to cite: International Whaling Commission, 2023. Report of the Scientific Committee: Annex A-C. J. Cetacean Res. Manage. (Suppl.). 24: 191-206.

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IntroductionPopulation abundance is amongst the most basic and crucial parameters for the assessment of conservation status of any species. Three species of odontocetes, all represented by local subspecies, inhabit the Black Sea: the Black Sea common dolphin Delphinus delphis ponticus, the Black Sea bottlenose dolphin Tursiops truncatus ponticus, and the Black Sea harbour porpoise Phocoena phocoena relicta. Their populations are threatened by multiple factors, including overfishing of their prey, bycatch, pollution and epizootics. Despite this, there are no basinwide estimates for any cetacean species in the Black Sea.MethodsIn 2019, a systematic study was carried out under the EU CeNoBS project. Six strata were designed in the waters of Bulgaria, Georgia, Romania, Türkiye and Ukraine, covering most of territorial and offshore waters, which were surveyed between June 19 and July 4. A line transect distance sampling approach was used, following predefined transects within each stratum, achieving a 5% coverage of the surveyed area. A total of 7,344 kilometres of transects were surveyed recording a total of 1,744 cetacean sightings. Design-based abundance estimates were obtained using a Multiple Covariate Distance Sampling (MCDS) approach. Model-based abundance estimates were also derived using a Generalized Additive Models (GAM) approach, linking species sightings with a number of environmental covariates (e.g., bathymetric features, sea surface temperature, chlorophyll-a) over a grid of 10x10 km.Results and discussionThe uncorrected (for perception and availability bias) estimates obtained through the model-based analysis were 108,283 (CV=0.07) common dolphins, 22,720 (CV=0.15) bottlenose dolphins and 93,808 (CV=0.06) harbour porpoises. These aerial surveys yielded the first insights on overall abundance, density and distribution, providing current regional baseline values and density maps for all three cetacean species of the Black Sea during the summer months, to be used for the elaboration of effective conservation measures and to address national and international requirements.

Biologging and habitat modelling are key tools supporting the development of conservation measures and mitigating the effects of anthropogenic pressures on marine species. Here, we analysed satellite telemetry data and foraging habitat preferences in relation to chlorophyll-a productivity fronts to understand the movements and behaviour of endangered Mediterranean fin whales (Balaenoptera physalus) during their spring–summer feeding aggregation in the North-Western Mediterranean Sea. Eleven individuals were equipped with Argos satellite transmitters across 3 years, with transmissions averaging 23.5 ± 11.3 days. Hidden Markov Models were used to identify foraging behaviour, revealing how individuals showed consistency in their use of seasonal core feeding grounds; this was supported by the distribution of potential foraging habitat. Importantly, tracked whales spent most of their time in areas with no explicit protected status within the study region. This highlights the need for enhanced time- and place-based conservation actions to mitigate the effects of anthropogenic impacts for this species, notably ship strike risk and noise disturbance in an area of exceptionally high maritime traffic levels. These findings strengthen the need to further assess critical habitats and Important Marine Mammal Areas that are crucial for focused conservation, management and mitigation efforts.

After the near-complete cessation of commercial whaling, ship collisions have emerged as a primary threat to large whales, but knowledge of collision risk is lacking across most of the world's oceans. We compiled a dataset of 435,000 whale locations to generate global distribution models for four globally ranging species. We then combined >35 billion positions from 176,000 ships to produce a global estimate of whale-ship collision risk. Shipping occurs across 92% of whale ranges, and <7% of risk hotspots contain management strategies to reduce collisions. Full coverage of hotspots could be achieved by expanding management over only 2.6% of the ocean's surface. These inferences support the continued recovery of large whales against the backdrop of a rapidly growing shipping industry.

Acoustic surveys for sperm whales (Physeter macrocephalus) were conducted in the Mediterranean Sea in summer 2018 as part of the vessel-based component of the ACCOBAMS Survey Initiative (ASI). Equal-spaced zigzag transects provided uniform coverage of key sperm whale habitats and were surveyed using a towed hydrophone array deployed from a research vessel at speeds of 5-8 knots. A total of 14,039 km of tracklines were surveyed in the western basin, Hellenic Trench and Libyan waters, with an acoustic coverage of 10% realised for sperm whales. During these surveys, 254 individual sperm whales were detected on the trackline, with an additional 66 individuals off-track. Sperm whales were only seen ten times on-track, with an additional 16 off-track sightings. Estimates of slant range to echolocating whales were used to derive density estimates through both design- and model-based distance sampling methodologies. An acoustic availability of 0.912 (sd = 0.036) was derived from via published models. When correcting for availability bias, a design-based abundance estimates of 2,673 individuals (95% CI 1,739-4,105; CV = 0.21) was derived for the surveyed blocks, which incorporated most known sperm whale habitat in the Mediterranean Sea. The equivalent model-based estimate was 2,825 whales (2,053-3,888; CV = 0.16). Over 97% of detected whales were in the western basin, with highest densities in the Algerian and Liguro-Provencal Basins between Algeria and Spain/France. In the eastern basin, detections were sparse and concentrated along the Hellenic Trench. A density surface modelling (DSM) exercise identified location and benthic aspect as being the most instructive covariates for predicting whale abundance. Distance sampling results were used in a power analysis to quantify the survey effort required to identify population trends. In the most extreme scenario modelled (10% per annum decline with decennial surveys), the population could have dropped by 90% before the decline was identified with high statistical power. Increasing the regularity of surveys would allow population trends to be detected more expediently. Mediterranean sperm whales are listed as Endangered on the IUCN’s Red List and the need for urgent conservation measures to reduce injury and mortality remains paramount for this unique sub-population.

The Mediterranean fin whale (Balaenoptera physalus) subpopulation is under threat from collisions with ships. Given the international dimension of the issue, the French, Italian, Monegasque and Spanish governments have proposed a Particularly Sensitive Sea Area (PSSA), i.e., a management zone of the International Maritime Organization (IMO), in which mandatory and voluntary protective measures can be implemented. Defining the risk and its impact at the subpopulation level is required to improve the chances of an IMO acceptance for such a proposal. While previous research partially succeeded in defining the collision risk, its impact on the subpopulation has not been thoroughly evaluated, especially at the spatial scale of the envisioned PSSA. Our study uses the carcass recovery approach to estimate the number of deadly collisions within the proposed PSSA. We then assess the probability that this number exceeds three management rules: Potential Biological Removal (PBR), Alert Reference Point (ARP) and Critical Reference Point (CRP). These management rules describe thresholds beyond which (a) the incidental mortality may prevent the recovery of the population within 100 years (PBR), (b) there is a cause for concern about incidental mortality (ARP), and (c) there is a critical need to lower the incidental mortality (CRP). We conclude that mortality from collisions alone is in excess of PBR. Taking into account confirmed and suspected collisions in strandings in calculations, the collision mortality exceeds ARP; this threshold being considered unacceptable by some international organisations. Additionally, there is almost a 35% chance that the mortality due to ship strikes exceeds the CRP, likely resulting in a population decline. The probability of anthropogenic mortality exceeding CRP is 60% if we include the fishery-related mortality in stranding (i.e., taking into account the total incidental mortality from bycatch and ship strikes). The PSSA proposal could use our approach to estimate the impact of collisions and assess the effectiveness of implemented protective measures. However, it is important to highlight that the IMO process for establishing a PSSA is lengthy, and our findings show that immediate action is required, as there is a high probability that the ship strike and fishery mortality is beyond the critical threshold fixed by the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic area (ACCOBAMS).

With the continuous intensification of marine traffic worldwide, whale-vessel collisions at sea (or “ship strikes”) have become one of the primary causes of mortality for cetaceans and a widely recognised cause of concern for human safety and economic losses. The Mediterranean Sea is a global hotspot for whale-vessel collisions, with one of the highest rates involving large cetaceans, especially the endangered fin whales (Balaenoptera physalus) and sperm whales (Physeter macrocephalus). Evidence indicates that both species are experiencing higher chances of a fatal collision than what predictions have estimated so far, with ship strikes being the main human-induced threat in the area. Regional and international organisations have stressed the need to address the issue by investigating the projected impacts of ship strikes on whale populations and by identifying possible mitigation measures to reduce chances of collision. Amongst the most popular and feasible options, there is the improvement of animal detection during navigation. Here, we present SEADETECT, a LIFE project that aims at developing an automated detection system to reduce vessel collision risk with marine mammals and unidentified floating objects (UFOs), combining state-of-the-art and novel technologies with existing approaches in the study of large whale ecology. This detection system consists of three elements; an automated onboard detection system composed of several sensors, a real-time passive acoustic monitoring (PAM) network at sea and a real-time detection-sharing and alert system (REPCET®). In this paper, we propose the development of a mitigation measure framework tailored for the issue of collision with fin and sperm whales in the north-western Mediterranean Sea, but that has the transferability features necessary for its application in other high-risk areas for ship strikes worldwide.

To assess cetacean densities in the Pelagos Sanctuary for Mediterranean Marine Mammals, a Marine Protected Area (MPA) specifically designated to protect cetaceans, a survey was carried out in the Ligurian-Provencal Basin (NW Mediterranean) in August 2008. An area of 58,000 km2 was surveyed in eight days with equally spaced zigzag transects, covering 1,255 km in favourable conditions. Tracklines were designed using Distance 5.0 to allow for homogeneous coverage probability over the selected area. Fifty three sightings of four cetacean species were made: striped dolphins (n = 37), fin whales (n = 12), sperm whales (n = 3) and Cuvier’s beaked whales (n = 1). Estimates of abundance were obtained using Distance 5.0. The estimated dolphin abundance was 13,232 (CV = 35.55; 95% CI = 6,640–26,368), with a density of 0.23 individuals km–1 (CV = 35.55; 95% CI = 0.11–0.45). No fin whale abundance estimate was possible due to the small sample size. The point estimate of the 2008 striped dolphin abundance estimate was almost half of that of a survey conducted in 1992 by Forcada and colleagues (1995) in the same area with comparable effort, platform and methodology (25,614; CV = 25.3; 95% CI = 15,377–42,658); nevertheless, the difference was not statistically significant. These results strongly support the need for further systematic monitoring in the Sanctuary and in the surrounding areas, in order to assess striped dolphin abundance, spatial and temporal trends.

In the Mediterranean, incidental captures in fishing gear contribute to the high mortality of loggerhead turtles (Caretta caretta). Understanding the effects of bycatch is complex and requires robust knowledge of baseline population parameters such as abundance and density, as well as an understanding of animals' distribution in relation to commercial fishing efforts. Based on data collected during multi-species line transect aerial surveys conducted between 2009 and 2017, we present density and abundance estimates, corrected for availability bias, for a large sector of the central Mediterranean, discuss temporal and spatial patterns and provide Potential Biological Removal (PBR) values for the monitored areas. Sightings data were also used to evaluate the spatial and temporal usage areas. Strong latitudinal and longitudinal gradients in density, abundance and area usage emerged from the analysis, with turtles occurring in higher numbers in the deeper pelagic waters of the Tunisian Plateau, the Ionian Sea and the Gulf of Taranto, irrespective of the season. PBR values derived from this study are likely unsustainable. This paper investigates the implications of commercial fisheries for Mediterranean loggerhead turtles across an area rarely included in sea turtle monitoring and has the potential to be relevant towards informed management and conservation of this species and highlights the necessity of international collaborative efforts in the region.

The ACCOBAMS Survey Initiative (ASI) is the first synoptic large-scale survey of the entire ACCOBAMS Area and as such it plays a key role in filling the current gaps in our biological and ecological knowledge of large vertebrate species occurring in the region. Data gathered during the ASI were analyzed in a distance sampling surface-modelling framework to assess the summer distribution, densities and patterns, as well as to investigate the correlates of these parameters, for large vertebrate species and taxa in the Mediterranean Basin. Static and dynamic explanatory variables, including water depth (m), distance to depth contours (km), distance to canyons and seabed slope (km), sea surface temperature (°C), mixed layer depth (m) and levels of chlorophyll-a (mg/l), were considered to predict density and compute its variance spatially at a resolution of 10x10 km. A strong longitudinal gradient from low densities in the east to high densities in the west is shared by most taxa. In addition, several taxa also showed a less marked latitudinal gradient varying in direction according to species, and finally, a few of them exhibited patchy distributions.

This paper investigates the distribution of Mediterranean fin whales (Balaenoptera physalus) between 1990-99 in the recently-established Pelagos Sanctuary for the Conservation of Mediterranean Marine Mammals. During the study period, 870 days were spent at sea, surveying a total of 73,046km, totalling 540 sightings of fin whales. Mean yearly whale encounter rates showed no significant differences in the first five years, but then steadily decreased between 1995-99. The highest encounter rates and largest mean aggregation size (mean=2.12; SD=1.32; SE=1.15) were in summer 1995 and the mean aggregation size throughout the study period was 1.75 (mode=1; SD=1.11; SE=0.05). Differences in mean aggregation size were significant between years, but not months. This is likely to be related to prey availability and to patchiness of plankton distribution. Generalised Linear Models were used to relate fin whale distribution to physiographic variables (mean, range and standard deviation of depth and slope, and distance from the nearest coast). Water depth was the most significant variable in describing fin whale distribution, with more than 90% of sightings occurring in waters deeper than 2,000m. This study demonstrates the deep water preference of fin whales in this area, emphasises the crucial role that this part of the western Ligurian Sea plays in the ecology of Mediterranean fin whales and provides recommendations for conservation and management measures in the area.