MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14771

ABSTRACT: Beaked whales (family Ziphiidae) are cryptic, deep diving cetaceans found offshore. Passive acoustic monitoring of this family allows identification to species and is instrumental in expanding knowledge of their behavior, distribution, and habitat use. From 28 June – 25 August 2016, two broadscale shipboard surveys towed a hydrophone array in the western North Atlantic. Concurrently, 11 bottom-mounted recorders collected continuous passive acoustic data during July and August 2016 along the 1,000 m contour. Five beaked whale species (goose-beaked [Ziphius cavirostris], Gervais’ [Mesoplodon europaeus], True’s [M. mirus], Sowerby’s [M. bidens], and Blainville’s [M. densirostris] beaked whales) were present in both datasets. Beaked whales were commonly detected at the bottom-mounted sites (71% total days present), with sites off the United States’ Mid-Atlantic Bight containing the greatest species diversity. Overall, daily co-occurrence was uncommon (35% of study period). Using the towed array, Blainville’s and Gervais’ beaked whales were found in the Gulf Stream, True’s beaked whales were more common in abyssal waters, and Sowerby’s were more common on the continental slope. Goose-beaked whales were present throughout. Using multipath reflections, click depths were examined for 192 beaked whale events. Among three species tested (goose-beaked, Gervais', and True's beaked whales), only goose-beaked whales were found to significantly forage in proximity to the seafloor. This is the first study of its kind to provide a comprehensive overview of how these whales utilize their habitat across latitudes, longitudes, and at depth.