Monitoring soundscapes provides data for several purposes, such as research and management. Marine megafauna, especially cetaceans, have been monitored at the Azores archipelago using the BOMBYX system, composed of 4 hydrophones. Besides recording biological sounds, anthropogenic noise was also recorded, due to the close location of shipping routes at SE of São Jorge island.

There are 28 species of cetaceans seen in the region, but the most frequent and more expected to be recorded are: Sperm whale, Bottlenose dolphins, Risso's dolphins, Common dolphins, Striped dolphins, Spotted dolphins, Blue whales, Fin whales, Sei whales, Humpback whales, Short-finned pilot whales, False killer whales, Cuvier's beaked whale, Mesoplodon densirostris, Mesoplodon bidens, Northern Bottlenose whales. There could also be records of Bryde's whale, Minke whale, Mesoplodon europaeus, Mesoplodon mirus, Pygmy sperm whale, Dwarf sperm whale.

The BOMBYX EUROPAM sonobuoy is equipped with real time transmission and powered by solar panels. With a small size, only 1m high, it supports a 1 m diameter acoustic antenna, that allows to diarize the different sources, anthropic and biophonic, in azimuth and elevation. It aims to monitor the interactions of the megafauna against anthropic pressure. It includes a real time species identification, and can thus alert on some risk of collision. We will present the overview of the Bombyx Surveys

How to cite: Oliveira, C., Glotin, H., Prevot, P., Barchasz, V., and Gies, V.: Megafauna survey in Acorez : perspectives with Bombyx Sonobuoy, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1174, https://doi.org/10.5194/oos2025-1174, 2025.

Cetacean inter-species communication remains a mystery. In some fjords of the Norwegian Arctic the concentration of their prey increases due to climate change, then also the megafauna concentration, resulting in accelerating competition and species interactions. We then aim to analyze this unknow cocktail party combining simultaneously several sources : (Orca orcinus * Megap. nov. * Baleno. physalus * Physeter
macro. * Landscape).

This is an incredible opportunity to record for the first time these pristine soundscapes during the short season of these whale runs. It has been related in a historic report of the end of the XIXth century that such whale groupement was frequent. But since the whale industry, only Oo were present. It is only after 10 years that gradually the other species investigated the area again, with most recently the Pm (nov. 2023).

Then the Center of Artificial Intelligence in Natural Acoustics (CIAN) [2] deployed its mobile acoustic laboratory on the PolarPod-Perseverance vessel. With its length of 42m, this exploration sail propulsion vessel is the future for CO2 balance, as well as for acoustic studies in dynamic conditions. Versatility and oceanographic skills of Perseverance are perfectly suited for this type of acoustic mission.

We deployed a small array, Manta-1, based on our custom hydrophones and AI embedded electronic sound card. Manta-1 was used for transects by
sail propulsion having a neutral impact on acoustics. We also deployed a fixed pentaphonic array and a long array. It resulted in a complex and
novel corpus of whale cocktail parties that has been processed by AI listening algorithms of CIAN [1]. We then model the nictemeral acoustic
cycles of each species and we test the 6x2 hypotheses of inter-species positive interactions (foraging collaboration), and negative
interactions (competition).

[1] ADAPREDAT, R Report, MITI CNRS, Glotin et al, (2024)
https://sabiod.lis-lab.fr/pub/ADAPREDAT/AAPSanteEnvironnement2022.2_Rapportfinal_GLOTIN_FJORD3D_202403.pdf

[2] https://cian.lis-lab.fr/

How to cite: Girardet, J., Glotin, H., Etienne, J.-L., Gies, V., Sarano, V., Paris, S., Jespers, S., and Giraudet, P.: PolarPod-Perseverance in Arctic listening with AI to the Old World Symphonia, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1445, https://doi.org/10.5194/oos2025-1445, 2025.

Cetaceans use methods based on acoustic signals to perceive the environment (echolocation)[1][2] and communicate due in part to the low visibility in this environment [3]. Studying these acoustic signals enables us to identify and understand these animals better. There are different methods to describe an acoustic signal, one of which involves using transformations to represent signal variations according to time and amplitude modulations [4]. These representations are called time-frequency representations (TFR). However, the TFR method usually used (by short-time Fourier transform) [5] to study cetaceans is not suitable for all types of emitted signals. It is shown here that the Ambiguity Function (AF), is a representation that provides information of transient signals in terms of Doppler and time delay [6]. This representation is used as input for an autoencoder, to analyze the latent space. The results obtained support the hypothesis that there are characteristics within the animal's click that are linked to its behavior and its age/sex. This work opens the door to more advanced analyses such as the ability to monitor populations, differentiate juveniles, males, and females, and improve our knowledge of these cetaceans, which are still little known to the general public.

[1] Griffin, D. R. (1944). Echolocation by blind men, bats and radar. Science.

[2] Griffin DR (1958) Listening in the dark, 2nd edn. Cornell University, New York.

[3] Au, W. (1993). The Sonar of Dolphins Springer, New York, pp. 32, 41–46, 66–70, 148–152.

[4] Sejdić, E., Djurović, I., and Jiang, J. (2009). Time–frequency feature representation using energy concentration: An overview of recent advances. Digital signal processing, 19(1):153–183.

[5] Allen, J. (1977). Short term spectral analysis, synthesis, and modification by discrete fourier transform. IEEE Transactions on Acoustics, Speech, and Signal Processing, 25(3):235–238.

[6] Max, J. (1987). Méthodes et techniques de traitement du signal et applications aux mesures physiques. vol. 2: Appareillage, méthodes nouvelles, exemples d’applications. Paris: Masson.

How to cite: Deloustal, N., Glotin, H., Paris, S., and Paiement, A.: Ambiguity function of biosonar cetaceans from HD observations and their automatic classification, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1562, https://doi.org/10.5194/oos2025-1562, 2025.

With the continuous increase of human activities at sea, predicting noise propagation from a given source is paramount to understanding the potential extent of its effects on the marine environment. Sound propagation models serve this purpose. These are complex modeling frameworks which account for both the physics of sound traveling in water as well as some environmental parameters which may affect it. However, in-situ sound measurements are required for validating such models, particularly at large distances from the source, where predictions can deviate largely from reality. Traditionally, such measurements are obtained from hydrophones placed on installations (buoys, landers) at fixed depths which do not allow verification of the vertical propagation of sound. In this study, a hydrophone was mounted on a mobile uncrewed platform (Slocum glider from Teledyne) which was moving up and down the water column as well as at different distances from the sound source during a full scale industrial seismic survey. The dBSea sound propagation model was used to predict sound levels from the seismic source and the measurements were used for validation. An array of simulations was performed to test which model settings best aligned with the data, with particular focus on the vertical propagation properties. This exercise gave insight on which areas of the model tend to either over- or underestimate sound levels and showed how autonomous diving platforms can help gather large amounts of high-quality sound measurements both in space and throughout the water column.

How to cite: Ramasco, V., Dunning, K., and Camus, L.: Autonomous diving platforms for high-quality sound measurements in space and throughout the water column, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1425, https://doi.org/10.5194/oos2025-1425, 2025.

The Tursionet project, funded by the Pelagos Initiative hosted by the Prince Albert II of Monaco Foundation, aims to study the acoustics interactions of bottlenose dolphins with different types of fishing gear from small-scale fisheries in the coastal waters in the Pelagos Sanctuary, a Marine Protected Area for marine mammals located in the Northwestern Mediterranean between France, Italy, and Monaco [1].

Several hydrophones have been deployed along the Ligurian coast near different types of static fishing gear (e.g. gillnets and pots) to monitor the acoustic interactions of bottlenose dolphins interacting with the nets and evaluate their frequency and possible impact.

The acoustics data collected will also be used to create an automated system to detect and signal the acoustic activity of dolphins to speed up the analysis for future works. Among the vast vocal repertoire of bottlenose dolphins [2], echolocation trains and final buzzes have been the most recorded and are thus the perfect candidate to build an automatic system of detection and classification. As in most automated systems, the data stream must go through several processing steps before it is fed into the classification system. In the present study, we investigate different preprocessing and feature extraction methods and test their advantages, disadvantages, and feasibility according to the classification system used.

This study aims to be a benchmark for the future and a table of discussion between different groups to find an optimal framework for the processing of acoustic signals of cetaceans, a crucial step in the pipeline of automated systems of cetacean bioacoustics.

[1] Tursionet project: https://www.tursionet.eu/en/
[2] Jones, B., Zapetis, M., Samuelson, M. M., & Ridgway, S. (2019). Sounds produced by bottlenose dolphins (Tursiops): a review of the defining characteristics and acoustic criteria of the dolphin vocal repertoire. Bioacoustics, 29(4), 399–440.
https://doi.org/10.1080/09524622.2019.1613265

How to cite: Lelong, D. M., Manghi, M., Fossati, C., Pavan, G., Marchini, A., Gnone, G., Garibaldi, F., Coppolella, E., Testori, C., Giorda, F., and Casalone, C.: Tursionet: detecting bottlenose acoustic interactions in the Pelagos sanctuary with small-scale fisheries. Aspects of acoustic data-preprocessing and detection techniques., One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1241, https://doi.org/10.5194/oos2025-1241, 2025.

The population of sperm whales, Physeter macrocephalus, classified as “Endangered” in the Mediterranean Sea by the IUCN, is threatened by human activities, even in the Pelagos sanctuary dedicated to them. Marine traffic, the densest in the world, is one of the main threats both by: 

- noise pollution which profoundly disrupts echolocation and communication, essential to the life of this large cetacean;

- collisions, the primary source of unnatural mortality for large cetaceans: 15% of the sperm whales we observed are injured by collisions (see photo).

In order to reduce the threats weighing on this very small population (a few hundred individuals), the Longitude 181 association has been carrying out, since 2022, jointly with CIAN, a study program (Whaleway expeditions) aimed at determining, both the preferred areas of presence, and the impact in these areas of anthropogenic noise on sperm whale activity. The method is based on a catalog of visual and acoustic (IPI) identity cards which allows the regular recapture of identified individuals, and on 3D acoustic recordings which allow the sperm whale to be positioned in the water mass, “click by click”, during hunting dives, with a precision never before achieved to date. Not only does this study open up a better understanding of social interactions in the night of the abyss (concerted hunting), but these daily (up to 4 consecutive days), monthly and annual recaptures allow us to draw up a detailed map of individual movements (see map) and relative area fidelity. Cross-referencing with other available catalogs reveals a mean recapture rate of around 2.5.

As a result, it is possible to compare this mapping to the movements of ships, thanks to their AIS, and to measure very finely the adaptation and disturbance caused by these anthropogenic aggressions. Ultimately, the aim is to make zoning proposals in the Pelagos sanctuary to request measures to preserve sperm whales.

Ref: H. Glotin et al, (2024): Bilan d’une décennie d’observations des grands cétacés en milieu anthropisé Nord Pelagos: BOMBYX, KM3Env, et antennes mobiles JASON. Programme de recherche triennal Pelagos 2021 – 2024 CIAN - DYNI LIS CNRS - Université de Toulon. 150.

Rendell L, Frantzis A. (2016): Mediterranean Sperm Whales, Physeter macrocephalus: The Precarious State of a Lost Tribe. In: Notarbartolo Di Sciara G, Podestà M and Curry BE, editors. Mediterranean Marine Mammals Ecology and Conservation. Advances in Marine Biology, Vol 75. Oxford: Academic Press; 2016. p. 37–74.

Frantzis A, et al (2019): Shipping routes through core habitat of endangered sperm whales along the Hellenic Trench, Greece: Can we reduce collision risks? PLoS ONE 14(2): e0212016. https://doi.org/10.1371/journal.pone.0212016

How to cite: Sarano, F. and Sarano, V.: Whale Way: a fine Physeter m. audiovisual survey , One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1569, https://doi.org/10.5194/oos2025-1569, 2025.