Passive acoustic monitoring is used as a tool to better understand the distribution, habitat use, and behavior of protected marine species such as the critically endangered North Atlantic right whale (NARW). This study aims to investigate variations in NARW calling behavior across several biologically important regions in the western North Atlantic. Archival passive acoustic data were analyzed from a subset of seven bottom–mounted recorders extending from the Gulf of Maine to the Chesapeake Bay from 2021–2023. Daily NARW upcall acoustic presence was evaluated using an automatic detector; each day with at least one validated automatic upcall detection (849 days) was then manually annotated to log every upcall. The number of upcalls per hour and number of hours with upcall activity were averaged for each site, revealing seasonal and diel trends. To further characterize upcall production, upcall parameters (i.e., duration, minimum and maximum frequencies) were measured and inter-call intervals were calculated to define calling bouts. Calling activity generally occurred throughout the day during peak seasonal presence at each site and more sporadically outside of these periods. The timing and frequency of upcall activity can provide insight to interpret changes in NARW behavior, with implications for management and conservation.
Koilpillai et al. (Wed,) studied this question.