Dynamic spatiotemporal acoustic occurrence of North Atlantic right whales in the offshore Rhode Island and Massachusetts Wind Energy Areas

Abstract

As development of offshore wind energy areas (WEAs) progresses along the US Atlantic coast, so will the spatiotemporal overlap and potential space-use conflict with vulnerable or protected wildlife, including Critically Endangered North Atlantic right whales (NARWs). Assessments of potential impacts from construction and operational activities on NARWs are dependent on the spatial, temporal, and acoustic overlaps between those activities and the occurrence of NARWs. Additionally, baseline distribution data of NARWs and data-driven policies are crucial to guide management decisions that minimize risk. The Massachusetts (MA) and Rhode Island-Massachusetts (RI-MA) Offshore WEAs currently comprise some of the largest lease areas and the first industry-scale offshore WEAs in the USA. Continuous passive acoustic data from 2011 through 2015 reveal highly variable seasonal, diel, and spatial NARW occurrence patterns within and near the MA and RI-MA WEAs. Under low (5th percentile) and median (50th percentile) noise conditions in the NARW communication frequency band (upcalls 71-224 Hz), we estimated detection ranges of 22 km (14 inter-quartile ranges [IQR]) and 8 km (5 IQR), respectively. Results underscore the influences of existing noise conditions on NARW communication and detectability within the MA and RI-MA WEAs. These dynamic NARW spatial and temporal occurrence data provide empirical support to enhance monitoring and mitigation strategies for minimizing risk to NARWs during periods of construction and identify time periods when heightened seasonal monitoring throughout the year during operations may be warranted.