Tethys’ contributions at the ECS conference 2023

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, V^1,2., 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 Genov^2,3

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

² 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 Genov^1,2, 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 Thompson^1.2, 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.