Experiment Details: Operation WhaleSonic: killer whale annotations

Pascale Hatt

Dept. of Information Technology and Electrical Engineering/Institute of Neuroinformatics/ETH Zürich

pascale.hatt@bluewin.ch

Not provided

Jörg Rychen, jrychen@ethz.ch Joseph Mine, josephmine95@gmail.com

Formal analysis, Investigation, Methodology

Yes

Yes

Operation WhaleSonic: killer whale annotations

Collect a dataset of acoustic and video recordings of cetaceans in the fjords around Skjervoy, northern Norway, using gps-equipped hydrophone arrays and drones

Skjervoy, Norway

30/11/2023 to 12/01/2024

Two participants together with a skipper form a team. They go out daily with the boat (as the weather and costs allow) and look for orcas. If suitable conditions are met, they deploy the four recorder buoys around the scene to record the underwater vocal communication. During recordings, the boat engine is usually shut off and the drones are operated to simultaneously record videos from the animals from above. When the animals leave the scene or the team’s work shift ends, the buoys are recollected. To maximise the throughput, we operate two teams in two shifts: One from midnight to early morning, and one from early morning to noon. Only the day shift will have a little daylight during which drones can be engaged. In the darkness, the animals have to be found via acoustic localization.

Hydrophone arrays We use a hydrophone array that consist of four custom built hydrophone recorders. The recorders are mounted in watertight enclosures that act as free-floating buoys. Each buoy is equipped with four hydrophones (HTI-96, High Tec Inc., USA) that hang 12 - 30 m below the water surface arranged in a tetrahedron structure with 50 cm side length. Each buoy has a GPS receiver to precisely record the position and to synchronize the acoustic signal acquisition with a temporal precision of ±100 ns with respect to GPS time. The recording is in the 10 Hz – 45 kHz frequency band. The buoys are deployed around a vocalizing group of orcas with a distance of several hundred meters between the buoys. Bottom-mounted hydrophone array We deploy seven SoundTrap 600 (OceanInstruments, NZ) on the sea bottom at a depth of 50-200 m. They continuously record for up to 90 days in the 10 Hz – 60 kHz frequency band. They can be recovered by an acoustic release (Ascent, InnovaSea). The assembly is similar to the one described in (Zitterbart et al., 2022). We are developing innovative methods to localize and synchronize the bottom mounted recorders. Synchronized drone recordings We use two drones (DJI Mini 3 Pro) to film the orcas while the buoys are recording. We fly the drones oriented north at a constant height (typically 30 m) and with the camera facing down. This allows to pinpoint the position of orcas with the help of an additional datafile from the drones that logs the GPS position and the barometer height with every video frame.

Not provided

Orcinus orca

Orcinus orca, Megaptera novaeangliae, Physeter macrocephalus, Balaenoptera physalus

Clupea harengus, boat engine noise, water and wave noise, seafloor noise, anchor noise, military activity noise

Killer whales are large marine mammals, with adults ranging in size from 5-8m and weighing between 4-7 tons. The orca is mostly black but with sharply bordered white areas. The entire lower jaw is white and from here, the colouration stretches across the underside to the genital area. The tail fluke (fin) is also white on the underside, while the eyes have white oval-shaped patches behind and above them, and a grey or white "saddle patch" exists behind the dorsal fin and across the back. Orcas live in matrilineal societies structured into family groups consisting of the eldest female and her descendants. Orcas feed on both fish, marine mammals and birds. Each orca population exhibits different behavioural features, including dietary specialization and foraging tactics. Furthermore, each population exhibits a distinct vocal repertoire. Generally, all killer whales produce vocalizations for both echolocation (navigation function) and communication (social function).

Vocal repertoires have been published for some, but not all of the world's orca populations: https://doi.org/10.1139/z05-089 https://doi.org/10.1080/09524622.2007.9753581 https://doi.org/10.1111/mms.13039 https://doi.org/10.3354/ab00353 http://hdl.handle.net/1721.1/43229 https://doi.org/10.1139/z95-124 https://doi.org/10.1098/rsos.191228 http://hdl.handle.net/2429/25787 https://doi.org/10.1080/09524622.2017.1396562

Killer whales inhabit all of the world’s oceans but occur in higher densities in cold waters closer to the poles.

Unknown, as we are not capable of identifying the identity of the signaller in our recordings. However, we typically observed between 1-40 individuals during our recording events.

No

No

https://drive.google.com/open?id=15Y4iKb4d9qCj4b0lMTy0t1xlEk6GdRRi

Of all recording files that i have, I already annotated killer whale calls in 4 recordings. I annotated calls in these recordings because they have a high density of killer whale calls or because they contain killer whale calls throughout the recording. Two of the recordings were too big to be uploaded here (>1GB), so only the other two were left. I used a random number generator which generated a random number (1 or 2). Since the result was 2 I selected the second of the two recordings.