Given new distribution patterns of the endangered North Atlantic right whale (NARW; Eubalaena glacialis) population in recent years, an improved understanding of spatio-temporal movements are imperative for the conservation of this species. While so far visual data have provided most information on NARW movements, passive acoustic monitoring (PAM) was used in this study in order to better capture year-round NARW presence. This project used PAM data from 2004 to 2014 collected by 19 organizations throughout the western North Atlantic Ocean. Overall, data from 324 recorders (35,600 days) were processed and analyzed using a classification and detection system. Results highlight almost year-round habitat use of the western North Atlantic Ocean, with a decrease in detections in waters off Cape Hatteras, North Carolina in summer and fall. Data collected post 2010 showed an increased NARW presence in the mid-Atlantic region and a simultaneous decrease in the northern Gulf of Maine. In addition, NARWs were widely distributed across most regions throughout winter months. This study demonstrates that a large-scale analysis of PAM data provides significant value to understanding and tracking shifts in large whale movements over long time scales.

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Abstract:Little is known about the ecology of many beaked whale species, despite concerns raised by mass strandings linked to certain sources of anthropogenic noise. Here, we used passive acoustic monitoring to examine spatial and temporal patterns in beaked whale occurrence at six locations along the continental slope in the western North Atlantic Ocean. We analyzed 2642 days of recordings collected between 2011 and 2015, and identified echolocation signals from northern bottlenose whales (Hyperoodon ampullatus), Cuvier's (Ziphius cavirostris), Sowerby's (Mesoplodon bidens), Gervais', (Mesoplodon europaeus), and Blainville's (Mesoplodon densirostris) beaked whales, and one signal type of unknown origin. We recorded multiple species at each site, with detections generally occurring year-round, and observed latitudinal gradients and site-specific variation in relative species occurrence. Notably, we regularly detected Cuvier's beaked whales in a region where they have not been commonly observed, and discovered potential habitat partitioning among Cuvier's and Gervais' beaked whales within their overlapping ranges. This information on the distribution and seasonal occurrence of North Atlantic beaked whale species offers new insight into patterns of habitat use, and provides a year-round baseline from which to assess potential anthropogenic impacts.