Groundtruthed probabilistic shipping noise modeling and mapping: Application to blue whale habitat in the Gulf of St. Lawrence

The Estuary and the Gulf of St. Lawrence constitute a large marginal sea of Northwest Atlantic of ∼260,000 km², which is crossed by the main shipping route to the Great Lakes and where ∼125 ships are cruising every time. This inland sea is also part of the habitat of the endangered Northwest Atlantic blue whale population, which frequent these waters throughout the year as indicated by a recent passive acoustic study. The present study aims at estimating the degree of blue whale exposure to shipping noise, in space and time, and the risks of auditory damages, behavioral responses and communication masking in this region. First, shipping noise radiated from the AIS-monitored traffic is modeled, mapped with a high time-space resolution, and validated using in situ measurements from a dedicated ANSI-compliant acoustic observatory along the seaway. The latter is also used to estimate the source levels of the ships. Shipping noise statistics over the region are then computed and risk metrics of blue whale exposure to shipping noise are estimated and mapped. These probability maps provide a useful tool to marine spatial planning management and to assess acoustic quality of blue whale habitats.