Habitat Modelling on the Potential Impacts of Shipping Noise on Fin Whales (Balaenoptera physalus) in Offshore Irish Waters off the Porcupine Ridge

Little is known about the ecological importance of fin whales found year-round in southwestern offshore Irish waters. Understanding their ecology is important to reduce potential harm through any spatio-temporal overlap with commercial shipping and fishing activities. This study explored the potential environmental drivers and impacts of low-frequency shipping noise on fin whale calling at Porcupine Ridge using the presence/absence of call detections as a proxy for observed changes due to possible masking. Acoustic call data was collected at a low sampling rate (2 ksps) from the end of March 2016 to June 2016 (97 days) using a bottom-moored autonomous acoustic recorder with an omni-directional hydrophone. The high zero-inflated and binary nature of the data was addressed using generalised linear models. The results of our habitat modelling predicted call detections to increase significantly during night-time (p & LE; 0.01) with sea surface height and chlorophyll-a concentration (p & LE; 0.01), implying higher prey availability may occur on Porcupine Ridge. It also indicated a significant decrease in call detections with increasing shipping noise (p & LE; 0.01). Unfortunately, the model had a type II error. To provide robust results, a longer study not limited by data on the prey, and oceanographic drivers including spatial and temporal parameters is required. This study provides the foundations on which further ecological data could be added to establish management and mitigation measures to minimize the effects of shipping noise on fin whales.

Automated summary

The study investigated the response of fin whales in the southwestern offshore Irish waters to low-frequency shipping noise, finding that whale call detections increase with night-time, sea surface height, and chlorophyll-a concentration, but decrease with increasing shipping noise. Further research is needed to establish robust management and mitigation measures to minimize the effects of shipping noise on fin whales.