Narwhals react to ship noise and airgun pulses embedded in background noise ...

• Main Authors: Tervo, Outi, Blackwell, Susanna, Ditlevsen, Susanne, Conrad, Alexander, Samson, Adeline, Garde, Eva, Hansen, Rikke, Heide-Jørgensen, Mads Peter
• Format: Dataset
• Language: English
• Published: Dryad 2021
• Subjects: FOS Biological sciences; airgun; Foraging; Arctic; Greenland; Scoresby; East Greenland; Monodon monoceros; narwhal*; Scoresby Sound
• Online Access: https://dx.doi.org/10.5061/dryad.000000046; https://datadryad.org/stash/dataset/doi:10.5061/dryad.000000046

Anthropogenic activities are increasing in the Arctic posing a threat to species with high seasonal site-fidelity, such as the narwhal Monodon monoceros. In this controlled sound exposure study, six narwhals were live-captured and instrumented with animal-borne tags providing movement and behavioural data, and exposed to concurrent ship noise and airgun pulses. All narwhals reacted to sound exposure by reduced buzzing rates, where the response was dependent on the magnitude of exposure defined as 1/distance to ship. Halving of buzzing rate, compared with undisturbed behaviour, and cessation of foraging occurred at 12 and ~7-8 km from the ship, respectively. The effect of exposure could be detected > 40 km from the ship. At distances > 5 km, the received high-frequency cetacean weighted sound exposure levels were below background noise indicating sensitivity of narwhals towards sound disturbance and demonstrating their ability to detect signals embedded in noise. Further studies are needed to evaluate ... : Six male narwhals were live-captured in August 2018 in the Scoresby Sound fjord system in East Greenland. The data were collected using animal-borne AcousondeTM acoustic and orientation recorders and backpack FastLoc GPS-receivers (Wildlife Computers (Redmond, Seattle, WA, USA) collecting an unrestricted number of FastLoc snapshots through August 2018. Acousondes were set to collect triaxial acceleration and orientation (sf 100 Hz), depth (sf 10 Hz), and acoustics. Acoustics was sampled continuously with a 25 811 Hz sampling rate (HTI-96-MIN hydrophone, nominal sensitivity -201 dB re 1 V / μ Pa, preamp gain 14 dB, an anti-aliasing filter with 3-dB reduction at 9.2 kHz and 22-dB reduction at 11.1 kHz, 16-bit resolution). The dataset has been processed as follows: Time-depth records were down-sampled to 1 Hz and time-synchronized with GPS positions. Additional GPS positions were created for each second between successive positions through linear interpolation. Buzzes were used as a proxy for foraging attempts ...