Drones have become a crucial research tool across marine environments over the past decade, being specifically useful in marine mammal research. Fin whales (Balaenoptera physalus) have been monitored feeding along the Catalan coast, Spain (NW Mediterranean), since 2014. To overcome issues such as the distance between a whale and a research vessel or the lack of distinctive dorsal fin features, an aerial identification technique was developed. It uses the fin whales’ characteristic central chevron pattern (CCP) and blaze, which are clearly visible from an overhead position. A total of 237 individual whales were identified between 2015–2022 in this study area, of which there were 35 interannual recaptures. While the dorsal fin may undergo modifications over time, the CCP and blaze patterns did not naturally alter over the years, with one whale displaying the same characteristics 8 years apart between the first and the most recent sightings. As such, this coloration pattern provides a reliable identification feature to be used for the interannual identification and population monitoring of fin whales using drones. This novel technique aims to improve and unify this species cataloguing overseas by using the CCP and blaze obtained from UAV (unmanned aerial vehicle) zenithal videos as a robust identification tool.

Ship strikes are a widespread conservation issue for many cetacean species globally. Population level impacts depend on the occurrence and severity of collisions, which may lead to life altering injuries or fatalities. Such impacts are a major concern for large, long-lived, and reproductively slow species like the fin whale. Since 2014, a seasonal feeding aggregation of fin whales has been monitored from February to June off the Catalan coast (Spain), in the northwest Mediterranean Sea. Oceanographical factors influence the occurrence and high density of krill within submarine canyons along the continental shelf, resulting in high whale abundance within a small spatial area. The study area extends 37 km offshore across a 1,944 km²marine strip situated between the towns of Torredembarra and Castelldefels. This fin whale feeding ground is exposed to high density marine vessel traffic, given its location between the northern Mediterranean shipping lane, which links Barcelona and Tarragona Ports to the Atlantic Ocean and wider Mediterranean Basin. Ship strikes represent the greatest conservation threat for fin whales in the Mediterranean Sea. At least four fin whales have been found dead in Barcelona Port since 1986 due to ship strikes and seven live whales have been documented with injuries in the study area since 2018. Fin whale distribution was mapped with known high-risk marine vessels’ (cargo, tanker and passenger vessels) shipping lanes. Vessel density and shipping lanes characterised by speed were considered. Collision risk was estimated monthly based on the predicted fin whale occurrence and traffic density. Several shipping lanes crossed the fin whale feeding habitat every month with an average speed of 15 kn. Cargo vessels displayed the highest ship-strike risk during April, overlapping with the peak of fin whale sightings in the critical feeding area. Slower vessel speeds (8 kn) in waters <200 m depth or along the continental shelf should be implemented along the Catalan coast, during the whale season. These suggestions should be applied into the Barcelona Port transport separation scheme. Ship strike risk for this species will persist unless active management plans are adapted in the region to mitigate its risk.

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.

The fin whale is the only whale species regularly found in the Mediterranean Sea, with a year around presence. However, the aquatic environment and the whale’s diving behavior have posed challenges to studying this marine mammal. The increasing use of drones in cetacean research has significantly enhanced our understanding of the species. Drones provide the ability to quickly and discreetly fly over the whales, minimizing the disturbance, while capturing high-quality footage that enables the observation of their behavior and characteristic features used for identification, as well as supporting morphometric analysis. Additionally, drones can assist in collecting blow samples and guiding research vessels for closer, more effective approaches to conduct biopsies, collect fecal samples, or deploy tagging devices. This technological advancement has greatly contributed to a deeper understanding of fin whales, offering valuable insights into the health of the population.

Morphological changes during body development measurements are crucial in understanding growth rates, allometric relationships, and sexual dimorphism. Recent advances in drone technology provide a new perspective enabling an indirect, non-invasive morphological assessment of free-ranging cetaceans. In this study, 10 body parameters were measured and examined with drone-based aerial photogrammetry across 82 individual fin whales (Balaenoptera physalus) along the Catalan coast of the Northwestern Mediterranean Sea, between 2021 and 2023. The growth pattern of each body parameter relative to the total length was determined as negative allometry. The developmental changes depicted that the head region at first decreases proportionally until the animal reaches approximately 14 m in length. Then, it remains constant until 18 m, subsequently followed by a relative increase. The difference in the growth rates among the sexes leads to a proportional shift between females and males approximately between 15 and 17 m in length. Overall, males exhibit a more rapid body elongation, along with moderate development of the other body parameters, while females display the contrary. The morphological parameters reveal insights into the population status dynamics and provide information on the reproductive status. These parameters are critical for the proper conservation and management of the local population of the species.

Understanding the movements of highly mobile marine species is essential for identifying critical habitats and developing effective conservation measures. Although occasional movements of fin whales ( Balaenoptera physalus ) between the Mediterranean Sea and the North Atlantic Ocean have been reported, the extent to which these movements represent a recurrent component of Mediterranean fin whale ecology remains unclear. Here, we present satellite telemetry tracks from seven fin whales (2022–2025) with five years of supporting evidence from systematic land-based observations (2021–2025) in the western Ibiza Channel to investigate movement patterns, behavior, and habitat use beyond the North-Western Mediterranean Sea. All tracked whales left the Mediterranean Sea passing through the Strait of Gibraltar and subsequently moved northward along the Atlantic coast of the Iberian Peninsula, providing direct evidence of cross-basin movements from the Mediterranean to the North Atlantic. Behavioral analyses using two independent movement-modeling approaches identified a common pattern of directed transit followed by area-restricted search (ARS) behavior—commonly associated with foraging—in several Atlantic areas, including waters off the Iberian Peninsula and the Bay of Biscay. The occurrence of prolonged ARS behavior in these areas is consistent with the use of Atlantic feeding habitats. The similarity of movement trajectories across individuals, years, tagging locations, and data streams indicates that seasonal use of Atlantic waters may represent a regular component of the movement ecology of at least some fin whales in the Mediterranean Sea. Given that these movements span multiple jurisdictions and areas of intense maritime activity, conservation measures should consider both important feeding habitats and the migratory routes that connect them.