Assessing risk of underwater noise impact on marine mammals throughout a new methodology

Abstract

Shipping noise has been identified as a threat on underwater ecosystems. In particular, several impacts have been documented on cetaceans, e.g., communication’s masking and stress increasing. To assess the risk related to such anthropogenic noise requires both quantifying the noise levels and estimating the distribution of the cetaceans’ population. However, current methods evaluating the risks related to anthropogenic pressures generally rely on strong expert priors, which may be difficult to define. This presentation aims at introducing a new framework for the comparison of anthropogenic pressure levels maps and cetaceans’ distribution in order to infer the risk of impact and provide management solutions. The methodology, combining simple statistical analyses and a theoretical representation tool was applied to the Bay of Biscay using shipping noise model and fin whale observation from regular surveys for the years 2012 and 2016. Relationships between cetaceans’ distribution and noise levels were investigated and linked to mammals theoretical responses to pressure. A trend analysis between 2012 and 2016 was also proposed to identify the noise hotspots. The results were interpreted in both terms of ecological meaning for fin whale and conservation measures for shipping noise, according to marine policies requirements.