Real-time acoustic observations in the Canadian Arctic Archipelago.

The main sources of noise in the Arctic Ocean are naturally occurring, rather than related to human activities. Sustained acoustic monitoring at high latitudes provides quantitative measures of changes in the sound field attributable to evolving human activity or shifting environmental conditions. A 12-month ambient sound time series (September 2018 to August 2019) recorded and transmitted from a real-time monitoring station near Gascoyne Inlet, Nunavut is presented. During this time, sound levels in the band 16-6400 Hz ranged between 10 and 135 dB re 1 µPa2/Hz. The average monthly sound levels follow seasonal ice variations with a dependence on the timing of ice melt and freeze-up and with higher frequencies varying more strongly than the lower frequencies. Ambient sound levels are higher in the summer during open water and quietest in the winter during periods of pack ice and shore fast ice. An autocorrelation of monthly noise levels over the ice freeze-up and complete cover periods reveal a ∼24 h periodic trend in noise power at high frequencies (>1000 Hz) caused by tidally driven surface currents in combination with increased ice block collisions or increased stress in the shore fast sea ice.

Underwater sound levels in the Canadian Arctic, 2014-2019.

The Arctic has been a refuge from anthropogenic underwater noise; however, climate change has caused summer sea ice to diminish, allowing for unprecedented access and the potential for increased underwater noise. Baseline underwater sound levels must be quantified to monitor future changes and manage underwater noise in the Arctic. We analyzed 39 passive acoustic datasets collected throughout the Canadian Arctic from 2014 to 2019 using statistical models to examine spatial and temporal trends in daily mean sound pressure levels (SPL) and quantify environmental and anthropogenic drivers of SPL. SPL (50-1000 Hz) ranged from 70 to 127 dB re 1 µPa (median = 91 dB). SPL increased as wind speed increased, but decreased as both ice concentration and air temperature increased, and SPL increased as the number of ships per day increased. This study provides a baseline for underwater sound levels in the Canadian Arctic and fills many geographic gaps on published underwater sound levels.