Présence acoustique de baleines noires de l'Atlantique Nord (Eubalaena glacialis) entre 2017 et 2022 au large de la Nouvelle-Écosse (Canada)

Abstract

The purpose of this study was to summarize the occurrence of North Atlantic right whale (NARW) upcalls on passive acoustic monitoring (PAM) datasets that have been collected by the Department of Fisheries and Oceans Canada (DFO) Maritimes Region from November 2017- September 2022. Throughout this period, acoustic data were collected from 27 sites off Nova Scotia, including multiyear data collection from the Grand Manan Basin and Roseway Basin NARW Critical Habitat areas. Confirmed acoustic presence of NARW at all recording sites analyzed as part of this study supports that NARW occur over a broad geographical range in eastern Canadian waters. On-shelf sites had higher upcall presence than slope sites, suggesting the Scotian Shelf is likely to be an important movement corridor for NARW. Upcall presence was highest in Grand Manan and Roseway Basins, indicating that these areas remain important habitats for NARW off Nova Scotia. Relatively high upcall presence in Emerald Basin indicates that this area is also commonly used by NARW. Upcalls were present in the Cabot Strait throughout summer and fall, but further data collection is required to more fully understand how NARW use this area. This study also demonstrates that NARW occur in waters off Nova Scotia throughout the year. In general, upcall presence was lowest in winter (though calls were still detected at multiple sites over multiple days in this season), increased over spring and summer, and was highest in fall. This study demonstrates the value of PAM for assessing occurrence of NARW in the region throughout the year, including during periods when weather makes visual survey efforts very challenging. PAM data not only complements visual sightings data, but in some cases provides more extensive or new information on presence of this species that could not be achieved from visual survey efforts. This information will be used to inform a revised NARW Recovery Potential Assessment (RPA), and a new assessment of NARW important habitat off eastern Canada.