Acoustic of cetaceans
Acoustic is a science that Moidjio has embraced since the early stage of it creation. These animals can be very vocal and exploit the water properties to emit a variety of sounds that will suit their needs for navigation, hunting, communicating, interacting with each others, singing ! We started our first recordings with hand made hydrophones aiming to collect the middle low frequency songs of Humpback whales and it was really challenging to get good affordable material. Time going, we had the chance to have hands on more performant hydrophones and recorders, allowing us to visualise higher spectrum of frequencies.
Humpback whale, Comoros 2018
Humpback whale song, Comoros 2016
Humpback whale vocal organ
Since 2016, we are recording humpback whales songs in the Comoros. In 2018, we started a collaboration with 4 other organisations in the view to better understand the vocalisation pattern of humpback whales in the region and the communication and learning behaviour of humpbacks during the breeding season.
Biagio Violi, PhD student from Genoa University, Italy, Vis-president of Menkab (Accobams partner and sister organisation), collected dozen of hours of whales vocalisation for the regional program. The program is supervised by Olivier Adams from the CNRS France.
Humpback whale knock sound, Comoros 2016
Humpback whale song theme, Comoros 2016
The mighty Spermwhale is a fantastic creatures that dives in the abyss of the oceans. It can reach up to 2000m depth in one dive and can hold his breath for long time and up to an hour. Spermwhales produce the most powerful and loud clicks of any cetaceans in the world. Their head is so big that clicks travelling within it are composed of multiple pulses. A first pulse (P0) is emitted by the right nostril by the contraction of a specific organ called the "monkey bag". This pulse travels all around but is concentrated backward through the "Spermaceti organ", banging on air sacs located on the skull plate and refracted into the "junk organ" to create a second pulse (P1). Most of the energy is concentrated forward but some of the pulse is refracted backward, passing back to the spermaceti organ and Junk organ, creating a third pulse (P2). Moidjio CRCAD has recorded spermwhales in Comoros, Turkey, Greece and Italy in 2018 and 2019. We are suspecting a migrating population in the Comoros and our team has recorded it 2 years in a raw but no visual yet!
Turkish male spermwhale 2018
20 Pilot whales, Comoros 2018
Pilot whales were recorded by Moidjio team in 2018. A pod of 15-20 individuals. A very beautiful recording made offshore Chindini village along the deep canyons of the South. Our recordings were made at less than 100m away from the pod. Pilot of Comoros produce whistles of relatively low frequency (6 to 10 KHz) with harmonics and synchronous clicks.
False killer whales
False killer whale, Comoros 2018
Cuvier beaked whales, Italy 2019
Cuvier beaked whale
Cuvier's beaked whales (CBW) has a very typical click design and it can easily be identified. Easy to identify but hard to detect with hydrophones from boat! CBW are cryptic animals and spend most of their time underwater, going down to 3000m, along the canyons, emitting clicks, only when they reach depth of the order of 300m. While at depth and emitting clicks, CBW is facing downward to the seafloor and scan the area with a narrow beam of clicks emitted in a regular and slow pattern. Having a moored hydrophone seems the best option to detect these animals... Easy to identify, yes ! It is a very long click, the longest of the cetacean kind. In the order of 400 microsec, with a series of zero-crossing about 9-10, a typical peak-frequency at 35-40 KHz, lower if you are far and it visualise as a frequency sweep in time that represent the wigner plot as a upsweep coma
Risso's Dolphin, Comoros 2018
Melon headed whale
Spinner dolphins, Comoros 2016
Stripped dolphins were recorded during a survey campaign in Montenegro with the Natural History association of Montenegro in 2018 and 2019. We collected the first acoustic samples of this species in the area. Stripped dolphins seems to be more active acoustically along the edge of the continental slope and at night. This dolphin can be found in depth >200m along the Adriatic pit and is fairly common there.