Tethys’ contributions at the ECS conference 2023

This year’s conference of the European Cetacean Society in O Grove, Galicia showcased a myriad of fascinating scientific works. Here are abstracts and posters, presented 16th to 20th April 2023, involving authors affiliated with Tethys.


Fin whale satellite telemetry to enhance place-based conservation efforts and mitigate threats in the North-Western Mediterranean Sea

Viola Panigada1,2, Thomas Bodey2, Luis Huckstädt3, Ari Friedlaender4, Eduard Degollada5, Beatriu Tort5, Simone Panigada1


1 Tethys Research Institute, c/o Acquario Civico, Viale G.B. Gadio 2, 20121 Milan, Italy

2 School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3FX, United Kingdom

3 Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall, United Kingdom

4 Institute of Marine Sciences, Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, United States

5 Associació EDMAKTUB, 08393 Barcelona, Catalonia, Spain

The current biodiversity crisis highlights the need to develop effective conservation measures for wildlife. Biologging offers an ideal method for informing management aimed at mitigating anthropogenic pressures on marine species. Here, we analysed satellite telemetry data to assess the movements and behaviour of endangered Mediterranean fin whales Balaenoptera physalus, a genetically isolated sub-population, during their regular spring aggregation in Catalan coastal waters. Eight individuals were equipped with Argos satellite transmitters in May 2021 (n = 3) and May 2022 (n = 5), with transmissions lasting 20 ± 8.5 days. Utilisation distributions were calculated to identify Core (50%) and Home (95% isopleths) range areas. A Hidden-Markov Model (HMM) was used to distinguish between two focal behaviours: area-restricted search (ARS; commonly associated with foraging) and transit. Dive profiles for one individual equipped with a depth-sensor were also analysed, as time spent at the surface has implications for ship strike risk. Tagged individuals were consistent in their behaviour across years and spent only ~45% of their time within the recently declared ‘Cetacean Migration Corridor’ Specially Protected Area of Mediterranean Importance (SPAMI). The HMM revealed that whales split their activity budgets approximately evenly between ARS (47%) and transit (53%). Depth-data recorded deeper dives during the day than the night, probably reflecting the diel vertical migration of their main prey Northern krill Meganyctiphanes norvegica. Our results provide behavioural detail to complement existing long-term survey data, confirming inter-annual consistency in core feeding grounds within the Balearic Sea and Gulf of Lion. As foraging behaviour occurred mostly outside currently protected areas, we propose enhancing conservation actions to mitigate ship strike pressure in an area of exceptionally high boat traffic. Strengthening ongoing transmitter deployments would increase both our understanding of this sub-population and its protection through place-based conservation efforts.


Reproductive parameters of a critically endangered Mediterranean subpopulation of bottlenose dolphins (Tursiops truncatus).

Carmen Andrés and Joan Gonzalvo

Tethys Research Institute, Milan, Italy

The bottlenose dolphin (Tursiops truncatus) is the only cetacean species present in the semi-enclosed Gulf of Ambracia, in Western Greece. While local density of dolphins is among the highest recorded in the Mediterranean Sea, this is not indicative of favourable conservation status or pristine habitat. This subpopulation was recently listed as Critically Endangered by the IUCN Red List of Threatened Species. In this study we examined reproductive parameters of female bottlenose dolphins inhabiting the Gulf, using over two decades of photo-id data (2001-2022) collected during 1,118 daily boat surveys, which allowed us to track the reproductive life of 40 females and their 112 calves. Our results showed that the calving season concentrates from May to October, reaching its peak in June, and a mean inter-birth interval of 3.8 ± 1.9 years (n= 71). By looking at the time of association between mothers and their offspring, we determined that 42 (38%) calves were successfully weaned, whilst 52 (46%) of them died within their first year of life, showing higher mortality rates than those described for other well-studied bottlenose dolphin populations (e.g., Port River Estuary and Shark Bay, Australia; Sarasota Bay, USA). For 7 reproductive females that we could track from birth, firstly identified as calves, we established 9.7 ± 2.3 years as their mean reproductive age, ranging from 7 to 12 years; none of their first new-borns survived. Data demonstrated variation in reproductive success among females, which suggest that some of them are more reproductively fit and, therefore, more important for the viability of the population. Our findings highlight the relevance of long-term dolphin studies as they can provide essential data on individual- and population-level parameters, with important implications for their conservation and management.

Using UAS-photogrammetry to monitor the age-structure and growth curve of a critically endangered Mediterranean subpopulation of bottlenose dolphins

Fabien Vivier1|*, Joan Gonzalvo2, Carmen Andres2, Kyleigh Fertitta1, Lars Bejder1,3 (in no particular order)

1Marine Mammal Research Program, Hawaiʻi Institute of Marine Biology, University of Hawaiʻi at Munoa, HI, USA

2Tethys Research Institute, Milan, Italy

3Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark

*Correspondence author: fvivier@hawaii.edu

Understanding the health status and population demographics of long-lived and slow-reproducing species is critical for their effective management. To inform conservation efforts, early detection of possible impacts of environmental and anthropogenic stressors on vital rates (e.g., fertility, survival) may aid in forecasting changes in population dynamics. However, it can take decades to detect population-level effects of perturbation using traditional monitoring approaches. Hence, having the ability to readily detect changes in biologically important parameters may provide an early warning of future trends in population dynamics. We used Unoccupied Aerial System- (UAS) photogrammetry to monitor the critically endangered Bottlenose Dolphin (Tursiops truncatus) subpopulation of the semi-enclosed Gulf of Ambracia in western Greece. UAS-based videos and boat-based photo-identification photographs of dolphins were collected for two one-week-long campaigns conducted in August 2021 and July 2022. A total of 10 days at sea, resulted in 149 identified individuals measured via UAS-photogrammetry methods, with 47 of those measured in both years, including 14 calves and juveniles. This work will present the results obtained from these measurements. First, we will calculate UAS-estimates of the dolphin’s total body length (TL). This will be done either directly, when individuals displayed a full body length, or indirectly, by using the distance between the blowhole and the anterior of the dorsal fin, exposed when surfacing. Then, we will develop the first age-length growth curve for this population and assess its age-structure combining UAS-estimates of TL and the known age of these individuals. Finally, we will attempt to detect pregnancy stages for the females sampled during Summer, using known or estimated dates of birth during Fall. Our work indicates that UAS-photogrammetry has the potential to be a powerful approach to readily and remotely monitor demographic parameters of free-ranging populations, particularly when traditional approaches may not be available.

Fixed-wing drones for monitoring cetaceans: a pilot study in the Pelagos Sanctuary (north-western Mediterranean Sea)

Airoldi S. 1, Costa M. 1, Lanfredi C. 1, De Santis V.1 and Giannelli, D.2

1 Tethys Research Institute, Viale G. B. Gadio 2, 20121, Milano, Italy

2 General Command of the Harbour Masters Corps – Italian Coast Guard, Viale dell’Arte 16, 00144, Roma, Italy

Unmanned aerial vehicles are increasingly being recognized as potentially useful for monitoring cetaceans. While most of the studies are conducted with multirotor drones, the use of fixed-wing is still very limited. Recently, the European Maritime Safety Agency (EMSA) provided Remotely Piloted Aircraft Systems (RPAS) to the Italian Coast Guard. This aircraft, used for multipurpose maritime surveillance missions, and search-rescue, was a TEKEVER AR5 Evolution, a medium-size (7.30×4.03m), fixed-wing RPAS, with 12 hours of endurance. The aircraft operated Beyond Radio Line Of Sight, with a satellite communication system, and was equipped with one electro-optical video camera (1080p), one Midwave Infrared sensor (512p), and one 20MP digital still camera. The pilot project “Eye in the Sky” was conducted within a partnership between the Italian Coast Guard and Tethys Research Institute to test the RPAS for cetacean monitoring. The survey took place in a small portion (1,041 km2) of the Pelagos Sanctuary from July to November 2022, covering 23 horizontal transects (34 km long and spaced 1.3 km). Different altitudes, video frames, and survey methodologies were tested. During the study period, 36 missions were conducted for a total of 100 hours and 10,126 km of observations, of which 63% were on transects, 13% were ad libitum, and 23% were with cetaceans, and 13,130 km of transfer. A total of six cetacean species were observed during 56 sightings: 20 fin whales, 12 striped dolphins, 7 sperm whales, 3 long-finned pilot whales, 2 Cuvier’s beaked whales, 1 Risso’s dolphin, and 11 unidentified species. RPAS are human-risk-free, non-invasive, with a small carbon footprint. Further tests are needed to improve the data collection system, but these encouraging preliminary results suggest that RPAS are an efficient tool for performing systematic monitoring of cetaceans in large marine areas and may represent a valuable complement to traditional survey platforms.


Potential signature whistles identified in groups of inner Mediterranean sub-population of long-finned pilot whales (Globicephala melas).

Antilli F.1-2, Lanfredi C.1, Pedrazzi G.2, Airoldi S. 2 and Pace D.S.2

(1) Tethys Research Institute, Viale G. B. Gadio 2, 20121, Milano, Italy.

(2) Department of Environmental Biology, Sapienza University of Rome, 00185 Rome, Italy

The long-finned pilot whale (Globicephala melas) is a highly social species with an extremely complex and structurally variable vocal repertoire. Very little is known on the repertoire of the Inner Mediterranean sub-populations (occurring from the eastern Alborán Sea to the Ligurian Sea). Here, the acoustic features of 919 pilot whales’ whistles (i.e., tonal, frequency-modulated sounds with a variable/aberrant contour) identified in 30 recordings collected between 2011 and 2020 in the north-western portion of the Pelagos Sanctuary (North-western Mediterranean Sea) are reported. Each whistle was characterized by extracting the maximum, minimum, starting and ending frequency, duration, number of inflection points and overtones, using Raven-Pro software. Then, the presence of potential signature whistles (pSW), a category of whistles used to transmit identity information within the group, was investigated using the SIGnature IDentification (SIGID) method based on the whistles’ repetition pattern (at least 5 times in an interval of 1–10 s). About 50% (n=430) of the analyzed whistles was classified as pSW, seemingly belonging to 17 different types (3 of which recorded in different years). Minimum and maximum frequency averaged 2.4±1.2 KHz and 10.2±4 KHz, respectively, with an initial frequency of 2.8±1.6 KHz, a final frequency of 4.5±3.8 Hz, and a duration of 1.1±0.4 seconds. The number of inflections and overtones averaged 1.5±3.3 and 2.5±1.5, respectively. pSWs maximum frequency and duration, and the overtones occurrence, resulted significantly higher than other whistles (Kruskal–Wallis H test, p<0.05), allowing discrimination between pSWs and non-signature whistles. Overall, the whistles’ maximum frequency, duration, and the number of inflection points seem higher than values reported in other geographical areas (Indian Ocean, Atlantic Ocean, Pacific Ocean), suggesting possible group-specific vocalization patterns (as in other matrilinear social species like killer whale, Orcinus orca) and/or effect of anthropogenic disturbance (such as noise).

Male sperm whales’ (Physeter macrocephalus) foraging activity in the Western Ligurian Sea (North-western Mediterranean Sea)

Comple, V1,2., Lanfredi, C.1, Pedrazzi, G.2, Airoldi, S.1, and Pace, D.S.2

1Tethys Research Institute, c/o Acquario Civico, Viale G. B. Gadio 2, 20121 Milano, Italy

2Department of Environmental Biology, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy

During foraging dives, sperm whales produce series of regular clicks interspersed with sequences of rapid–click buzzes called ‘creaks’, often followed by a few seconds of silence (“creak-pause” event), thought to be indicative of feeding attempts/success. Here, a total of 406 creaks in 163 recordings, collected between 2017 and 2021, were examined to assess the summer foraging activity in the North-western portion of the Pelagos Sanctuary (North-western Mediterranean Sea). Creaks and creak-pause duration, Inter-Click-Interval (ICI) and maximum frequency of the clicks were measured using Raven-Pro software. In addition, the depth at which the creak emission starts was estimated considering a descending swimming speed of 1.2 m/s. A creak rate (creaks/min, CR) was also calculated. These parameters were then associated with the presence of other individuals/species in the area (visually and acoustically assessed) and environmental parameters such as depth and slope, using QGIS software. Creak duration averaged 4.4±3.6 seconds (max=35, median=3.5), with higher values in social contexts (M-W U=5448, p<0.05). The mean creak-pause was 8.5±5.1 seconds and the ICI was 0.09±0.04 seconds. The maximum frequency of clicks in a creak was 32.1±7.4 kHz. Both the creak-pause (M-W U=9577, p<0.01) and ICI (M-W U=8758.5, p<0.05) were lower when other species (e.g., Risso’s or striped dolphins) were detected in the area. Creak emission generally started 8 minutes after the fluke-up, at an estimated depth of about 600 m, mainly in the mesopelagic environment. The CR was 0.37±0.09 creaks/min, showing significantly higher values in areas with lower depth (M-W U=1282, p<0.05) and slope variability (M-W U=1457, p<0.05), both in the continental slope and pelagic environments.  These results confirm the importance of both environments as specie’s critical habitats. These elements should be considered when managing risks derived from anthropogenic activities such as noise emissions and maritime traffic.

The Great Escape: Long-distance movements of two bottlenose dolphins between the Gulf of Ambracia (eastern Ionian Sea) and Gulf of Trieste (northern Adriatic Sea) 

Joan Gonzalvo1, Carmen Andrés1, Tilen Genov2,3

1 Tethys Research Institute, Italy

2 Morigenos – Slovenian Marine Mammal Society, Slovenia

3 Sea Mammal Research Unit, University of St Andrews, UK

While bottlenose dolphins (Tursiops truncatus) in the Mediterranean Sea often display a high degree of site fidelity, movements across substantial distances can occur and these can be inferred through re-sightings of identified individuals. The semi-enclosed Gulf of Ambracia (Greece) hosts one of the highest bottlenose dolphin densities in the Mediterranean. The local bottlenose dolphin subpopulation shows high levels of year-round site fidelity, constitutes a distinct subpopulation based on genetic and photo-identification data, and is listed as Critically Endangered by the IUCN Red List. Previously, three male dolphins regularly observed in the Gulf of Ambracia were subsequently photo-identified in various parts of the neighbouring Ionian Sea, as far south as the Gulf of Corinth 265 km away, not to be seen in Ambracian waters again.  Here, we report long-distance movements by two individuals, encompassing roughly 1000 km across the Ionian and Adriatic Seas, one of the longest reported movements for this species in the Mediterranean Sea. Two dolphins, a male and a female, first seen in 2003 and 2005, respectively, and repetitively observed in the Gulf of Ambracia until 2008, left the increasingly degraded Ambracian waters and were subsequently photo-identified and regularly observed in the Gulf of Trieste (northern Adriatic Sea) during 2013-2014. Such records indicate some degree of emigration from the Gulf of Ambracia, but no immigration into the Gulf has been recorded to date. The new records presented here also add to the growing body of evidence suggesting that Mediterranean bottlenose dolphins may be more mobile than was previously thought.

The Important Marine Mammal Area network: new updates on the growing tool for assisting global conservation efforts to protect marine mammal habitats

Margherita Zanardelli 1,3, Gill T. Braulik 1,2, Caterina Lanfredi 1,3, Gianna Minton 1,4, Simone Panigada 1,3, Elena Politi 1,3, Michael J. Tetley 1, Giuseppe Notarbartolo di Sciara 1,3, Erich Hoyt 1,5

1 IUCN Joint SSC/WCPA Marine Mammal Protected Areas Task Force, Gland, Switzerland

2 Sea Mammal Research Unit, University of St. Andrews, St. Andrews, Fife, UK

3 Tethys Research Institute, Viale G. B. Gadio 2, 20121 Milano, Italy

4 Megaptera Marine Conservation, The Hague 2242 PT, Netherlands

5 Whale and Dolphin Conservation, Chippenham, UK

The Important Marine Mammal Area (IMMA) programme was launched in 2016 by the IUCN Marine Mammal Protected Areas Task Force as a response to the conservation crisis in the protection of marine mammals and wider global ocean biodiversity. IMMAs identify discrete portions of habitat, important for one or more marine mammal species, which have the potential to be delineated and managed for conservation. Scientific experts identify IMMAs during regional workshops, on the basis of satisfying one or more of eight criteria covering critical aspects of marine mammal biology, ecology and population structure. Candidate IMMAs undergo independent peer-review prior to acceptance, and are then disseminated via a searchable database and dedicated online e-Atlas. Between 2016-2022, nine expert workshops – engaging more than 300 experts – have resulted in the identification of 209 IMMAs located in over 100 countries or territories, across two thirds of the world ocean. IMMAs identified to date provide important habitats for 78 of the 133 recognized marine mammal species. Around 32% of IMMAs in the network were identified on the basis of habitat for marine mammal species that are threatened on the IUCN Red List. Approximately 51% of IMMA surface areas occur within Exclusive Economic Zone waters, while 49% fall within areas beyond national jurisdiction. IMMAs are increasingly utilized in environmental impact assessments, marine-planning exercises, maritime traffic routing, as well as international, national, and regional conservation, policy and management initiatives. These include those governed through the Convention on Migratory Species and Convention on Biological Diversity, as well as the design and management of Marine Protected Areas (MPAs) and the development of MPA networks. The Task Force is working toward completing a global network of IMMAs that will contribute to the scientific information needed to fulfill the current collective goal of protecting 30% of the ocean by 2030.

New insights into sperm whale social units presence in the western Ligurian Sea (NW Mediterranean Sea)

Lanfredi C.1, De Santis V.1, Raineri R.1,2, Jahoda, M.1, and Airoldi S.1

1 Tethys Research Institute, Viale G. B. Gadio 2, 20121, Milano, Italy

Flash Vela d’Altura S.n.c Via Aurelia Ponente 50, Taggia Imperia, Italy

In sperm whale populations adult males are known to segregate from social units of females and immatures as they reach sexual maturity. This social pattern has been described also in the western Mediterranean, with males occurring in more northern waters, while social groups generally remain at lower latitudes. Since 1990 sperm whales have been reported with increasing frequency in the western portion of the Pelagos Sanctuary (north-western Mediterranean Sea) during summer. In this study photo-identification images, collected during surveys carried out from 1990 to 2022 in the north-western Ligurian Sea, were analysed with the aim to confirm the occurrence of females in the area. The presence of dorsal fin calluses was adopted as the primary identification criterion of gender. Group composition was assessed considering field estimates of the size, afterward confirmed through photo-id images. In over three decades of monitoring, 570 sperm whale sightings were collected. In 97% of the sightings, mainly sub-adult/adult males performing foraging activity were encountered in average group sizes of 1.4±0.5 (1990-2005) and 1.5±0.3 (2006-2022) individuals. Since 2017, four groups of females and calves were encountered during six different sightings, with two groups sighted twice. Their average group size was 8.3±4.9 individuals (min: 2 – max: 16). Eleven females showing calluses and seven calves were identified. The number of calves ranged from one to three per sighting. Re-sightings of females occurred only within the same season. Sightings were made over an average depth of 2,000 meters in an area affected by intense maritime traffic. Concerns are rising about the threats (such as the risk of collision with vessels) these vulnerable individuals are subjected to. Therefore, further effort is needed to verify the persistence of the social units with females and immatures in the area and to confirm if a shift in sperm whale distribution is occurring.

Movements of bottlenose dolphins: challenging the existing narratives?

Tilen Genov1,2, Jure Železnik1, Monica Francesca Blasi3, Chiara Bruno3, Davide Ascheri4, Elena Fontanesi4, Carmen Andrés5, Joan Gonzalvo5

  • Morigenos – Slovenian Marine Mammal Society, Piran, Slovenia
  • Sea Mammal Research Unit, University of St Andrews, United Kingdom
  • Filicudi WildLife Conservation, Lipari, Italy
  • Delfini Del Ponente APS, Imperia, Italy
  • Tethys Research Institute, Milan, Italy

Correspondence: tilen.genov@gmail.com

Understanding movements and connectivity among marine mammal populations means a better understanding of gene flow and potential isolation of populations, which is fundamental in an attempt to delineate units to conserve and help place demographic parameters, such as abundance, fecundity and mortality, in an appropriate population and conservation context. However, even in species we perceive as well studied, our understanding of these processes is incomplete. Common bottlenose dolphins (Tursiops truncatus), among the best-studied cetaceans and often ‘coastal’ in their distribution, are traditionally considered relatively ‘resident’ and demonstrating strong site fidelity to specific areas. While this is often true, this perception may partly be an artefact of the distribution and ‘habitat use’ of cetacean researchers, rather than animals themselves, and bottlenose dolphins have been shown to be capable of substantial movements, often in relatively short periods of time. Here, we outline recent advances in our understanding of bottlenose dolphin movements and how this may affect inferences about things such as population structure, population discreteness, spread of behaviours, and conservation management strategies. We provide new data on long-distance (1000 km+) movements, including the world’s longest recorded movement in coastal bottlenose dolphins, and provide recommendations for further research. We show that the emerging available data challenge the traditional view held of bottlenose dolphin movement patterns and that they make substantial movements more often than is currently recognised. This shows that we have yet to fully understand the ecology and behaviour of a species we consider well studied.

Threatened cetaceans off the coast of Israel and long-range movement of a sperm whale.

Kirsten F Thompson1.2, Jonathan Gordon3, Thomas Webber2 Yotam Zuriel4, Kim Kobo4, Dan Tchernov4, Sabina Airoldi5, Biagio Violi6, Alessandro Verga 7, Aviad P Scheinin4

1 Greenpeace Research Laboratories, University of Exeter, Exeter, United Kingdom

2 Biosciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom

3 Marine Ecological Research, Newport on Tay, Fife, United Kingdom

4 The Morris Kahn Marine Research Station, Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Ashdod, Israel

5 Tethys Research Institute, Milano, Italy

6 Menkab, Il respiro del mare, Savona, Italy

7 Golfo Paradiso Whale Watching, Carnogli-Genova, Italy


The Mediterranean Sea is impacted by anthropogenic pressures that interact synergistically with climate change.  Cetacean communities are diverse, and some Mediterranean populations are globally distinct. Surveys in the western Mediterranean have shown that sperm (Physeter macrocephalus) and Cuvier’s beaked whales (Ziphius cavirostris) are small, distinct populations that face numerous threats and are in decline. The Eastern Mediterranean is less well studied, and few surveys have investigated the composition of cetacean communities. In this study, we conducted visual-acoustic surveys off the coast of Israel during April–May 2022.

We detected sperm whales (three encounters), Cuvier’s beaked whales (one encounter), bottlenose dolphins (one encounter, (Tursiops truncatus)) and unidentified delphinids (17 encounters). Sperm whales were feeding approximately 10 km off Haifa, at 370–1720m deep. Codas corresponded to the Mediterranean dialect. One sub-adult male photographed is known from ten previous encounters in the Ligurian Sea.

Israeli water clearly provide habitat for cetaceans, including two globally threatened subpopulations – sperm and Cuvier’s beaked whales – that are of conservation concern and negatively impacted by noise. Given the intensity of human activities in Israeli waters, we suggest more survey effort is urgently needed and urge caution in issuing new permits for oil and gas prospecting and extraction.

SCANS-IV: Small cetacean abundance in European Atlantic waters and the North Sea in 2022

A Gilles1, M Authier2, N Ramirez-Martinez1, H Araújo3, A Blanchard2, J Carlström4, C Eira5, G Dorémus2, C Fernández-Maldonado6, SCV Geelhoed7, L Kyhn8, S Laran2, D Nachtsheim1, S Panigada9, M Sequeira10, S Sveegaard8, N L Taylor11, K Owen4, C Saavedra12, V Ridoux2, J A Vázquez-Bonales12, B Unger1, PS Hammond13

  1. Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Buesum, Germany
  2. Observatoire Pelagis, UAR 3462, CNRS-La Rochelle University, La Rochelle, France
  3. Department of Biology & ECOMARE, Aveiro University, Portugal
  4. Department of Environmental Research and Monitoring, Swedish Museum of Natural History, Stockholm, Sweden
  5. Department of Biology & CESAM & ECOMARE, Aveiro University, Portugal
  6. Seashore Environment and Fauna, Tarifa, Spain
  7. Wageningen Marine Research, Den Helder, The Netherlands
  8. Department of Ecoscience, Aarhus University, Roskilde, Denmark
  9. Tethys Research Institute, Milano, Italy
  10. Instituto da Conservação da Natureza e Florestas (ICNF), Lisbon, Portugal
  11. Joint Nature Conservation Committee, UK
  12. Oceanographic Centre of Vigo, Spanish Institute of Oceanography, Spanish National Research Council (IEO-CSIC), Vigo, Spain
  13. Sea Mammal Research Unit, University of St Andrews, UK

A series of coordinated large-scale surveys for small cetaceans in the North Sea and adjacent waters was initiated in 1994 (SCANS) with the aim to obtain first comprehensive estimates of abundance of regularly occurring species to place estimates of bycatch and other anthropogenic mortality in a population context. Previous surveys (SCANS-II 2005/CODA 2007, SCANS-III 2016) have been completed on a decadal basis to monitor species and provide data to estimate trends. However, more frequent estimates (every 6 years) are needed to provide output for European Union Member States that need to report under both the Marine Strategy Framework Directive (Article 8) and the Habitats Directive (Article 17) as well as to complete indicator assessment under OSPAR and HELCOM. In summer 2022, SCANS-IV was successfully completed in a study area of approximately 1.8 million km2 ranging from the Strait of Gibraltar to southern Norway, thus achieving the largest coverage and effort of all SCANS surveys to date. Data were collected by aerial survey (> 70,000 km covered) using the circle-back method for eight teams, and by a ship survey (> 4,500 km covered) in offshore waters of the Bay of Biscay using the two-team tracker method to account for animals missed on the transect line. More than 5,000 sightings of 17 cetacean species were recorded. Design-based abundance estimates for several species will be presented, including harbour porpoise, common, striped, bottlenose and white-beaked dolphin, minke, fin, sperm and beaked whales. Using these new estimates, which total more than 1.5 million animals, the aim is to thoroughly evaluate and assess the conservation status of different species and Good Environmental Status (GES) of the covered areas as well as multiple other evidence needs for cetaceans in European Atlantic waters.

Occurrence and Haul-out Pattern of a Mediterranean Monk Seal Colony Inhabiting the Inner Ionian Sea Archipelago, Greece.

Manel Gazo1, André Guinand2, Julien Pfyffer2, Carmen Andrés3 and Joan Gonzalvo3

1 Dept. Evolutionary Biology, Ecology and Environmental Sciences -IRBio- University of Barcelona, Spain

2 Octopus Foundation, Switzerland

3 Tethys Research Institute, Italy

Mediterranean monk seal (Monachus monachus) distribution within the Mediterranean Sea is changing. Confirmed observations of monk seals, in areas where they were previously considered eradicated from, are increasingly reported. Favorable improved conditions, namely reduction on intentional killings, access to key habitat and prey  may benefit the species, leading to its re-establishment through stragglers arriving from better-established adjacent populations. Here we present the results of four years of monk seal monitoring in Formicula, an islet within the Inner Ionian Sea Archipelago (Nat 2000 site GR2220003), Greece. Two autonomous monitoring systems were installed inside two caves used by seals. Each system, run independently and took a picture of the haul out site inside the caves every 15 minutes. Between May 2019 and October 2022, a total of 1,040 days of effective monitoring were conducted resulting in 99,840 images. Monk seal presence was established in 34.7% of the days in 2019, 42.6% in 2020, 77.1% in 2021 and 41.4% in 2022. Seal presence was observed across the year, being autumn the most frequented season (57.3%). Concerning the haul-out pattern seals arrived at the caves primarily around sunset-midnight (range 20:00h – 01:00h) and remained inside an average of 9h 15 min (range 2h 30min – 15h 15min). Typically, seals left the caves at sunrise, being the most common hour 06:00h-07:00h (35,5% of monitored haul-out events).  Monk seal aggregations included all age categories and both sexes, ranging from a single seal to up to 11 individuals. Some births were also registered in October 2021 and 2022. The present study sheds light on the use of haul-out sites in an area providing key habitat for Mediterranean monk seals. Data resulting from monitoring this endangered species, counting their aggregations and collecting evidence on their reproductive success will have important implications for the design of adequate management and conservation measures.