A software package calculating zones of impact on marine mammals around industrial noise sources

Abstract

A software package is presented which estimates zones of interference around underwater noise sources affecting marine mammals. An ocean sound propagation model based on ray theory computes the spreading of complex underwater sound such as broadband animal vocalizations and manmade noise. On a grid of receiver locations (representing the affected marine mammal), the received signal and noise sound spectra are compared. Given a species-specific audiogram, the software package plots zones of audibility around the noise source. Given species-specific vocalizations, zones of masking are plotted based on results obtained during an earlier study which measured masked hearing thresholds of a beluga whale. Tools developed during this study (such as an artificial neural network model to predict the amount of masking) can be linked to the software package. Zones of behavioral disturbance are plotted based on received sound levels reported in the literature. Zones of discomfort, injury, and hearing loss could be plotted if thresholds were known or using current estimates. The software package is applicable to a variety of ocean environments requiring location-specific oceanographic input data. The case of icebreakers affecting beluga whales in the Beaufort Sea is demonstrated.