Acoustic Modelling to Inform Policies: Mitigating Vessel Noise Impacts on Arctic Cetaceans Within the Tallurutiup Imanga National Marine Conservation Area

Abstract

Vessel traffic throughout the Canadian Arctic has tripled over the past 20 years and is not expected to decline. With the recent announcement of the Tallurutiup Imanga National Marine Conservation Area (TINMCA), the three endemic Arctic cetacean species are protected from hydrocarbon development, but vessel traffic is still permitted. To understand the potential impacts shipping noise could have on cetaceans within the TINMCA boundaries, a probabilistic model was developed for each term in a simplified sonar equation. The received (RL) and sound exposure levels (SEL) were calculated using a probability distribution of source levels (SL) derived from four years of ship traffic data. The calculated SLs, RLs and SELs did not reach levels that could result in temporary hearing loss, termed as temporary threshold shift limits, which are set out by the National Oceanic and Atmospheric Administration. Due to limited studies conducted on these three cetacean populations it cannot be assumed that they are not impacted or disturbed by vessel noise. Modelling the spread of underwater noise from the vessels transiting through the TINMCA helps develop spatial and vessel management tools. These tools can be used to mitigate the risks associated with vessel noise and the three charismatic Arctic cetaceans.

Keywords: Arctic; cetaceans; beluga; narwhal; bowhead; underwater noise; acoustic modelling; Tallurutiup Imanga; NMCA; RL; SEL; impacts