North Atlantic right whale localization and source level estimation using two coherently beamformed linear arrays

Two bottom-mounted, 32-channel coherently beamformed hydrophone line arrays were deployed off the coast of southern New England in March and April of 2022 in a demonstration supporting passive acoustic monitoring of marine mammals in the offshore wind construction area. On one day during that period, one or more North Atlantic right whales were detected and localized repeatedly over a two-hour period using cross-fixes measured from relative bearings to upcalls detected on both hydrophone arrays. Transmission loss (TL) testing in this region shows that the area can be characterized as a 17 log (R) environment at the 10-20 km ranges at which the whales were detected. Using the localizations and ranges to the whale(s), the received levels, and the TL, the North Atlantic right whale upcall mean source level is estimated to be 170 dB root-mean-square re 1 μPa @ 1 m (σ = 2.5 dB) for a sample size of n = 52 localized upcalls.