Distribution and abundance of beaked whales (Family Ziphiidae) Off Cape Hatteras, North Carolina, U.S.A.

Abstract

Beaked whales are vulnerable to the impacts of disturbance from several sources of anthropogenic sound. Here we report the distribution and abundance of beaked whales off Cape Hatteras, North Carolina, U.S.A., an area utilized by the U.S. Navy for training exercises, and of particular interest for seismic geophysical surveys. From May 2011 through November 2015, monthly aerial surveys were conducted at the site. Beaked whales were encountered 74 times (n 5 205 individuals) during these surveys. Ziphius cavirostris, the most commonly encountered species, was observed in every month of the year. Mesoplodon spp. were encountered in ten months of the year. Photographs of adult males with erupted teeth permitted six sightings to be identified conclusively as M. europaeus; M. mirus was also photographed just outside the study area. Beaked whale surface densities stratified by depth (0.005-0.007/km 2 ) were among the highest reported in the world for small ziphiids. A quantitative comparison of sightings and stranding records suggests that strandings do not accurately reflect the relative abundance of beaked whale species in this area. We conclude that Cape Hatteras, at the convergence of the Labrador Current and Gulf Stream, is a particularly important year-round habitat for several species of beaked whales.

Diving behaviour of Cuvier's beaked whales (Ziphius cavirostris) off Cape Hatteras, North Carolina

“…Cuvier's beaked whales occur year-round off Cape Hatteras, North Carolina, where they occur in very high densities [29–31] and exhibit strong site fidelity [7,32,33]. This area has complex topography characterized by a steep shelf break and multiple deep canyons, over which the Labrador and Gulf Stream currents converge.…”

Supernumerary teeth observed in a live True’s beaked whale in the Bay of Biscay

“…There have only been three published sightings of True’s beaked whales in the Bay of Biscay, most recently in 2003 (Weir et al, 2004). No erupted tusks were observed in these animals, and therefore identification was not definitive; however, a combination of identification features coincides with those of True’s beaked whales (McLellan et al, 2018).…”

Residency and movement patterns of Cuvier’s beaked whales Ziphius cavirostris off Cape Hatteras, North Carolina, USA

“…However, the continental slope waters off Cape Hatteras, North Carolina, USA, appear to be particularly important habitat, with occupancy and site fidelity demonstrated between seasons and years (Forney et al 2017, Waples & Read 2020. The species is present in high densities yearround in this area, with substantially fewer visual and acoustic detections in Norfolk Canyon to the north and Onslow Bay to the south (Stanistreet et al 2017, McLellan et al 2018.…”