Dive characteristics of Cross Seamount beaked whales from long‐term passive acoustic monitoring at the Pacific Missile Range Facility, Kauaʻi

Abstract

Beaked whale foraging pulses were detected on the Pacific Missile Range Facility (PMRF) off Kauaʻi, Hawaiʻi, via long term passive acoustic monitoring. The unidentified pulses do not match foraging pulses of known species on the range but are similar to the unidentified beaked whale first detected at Cross Seamount, Hawaiʻi. Although there has not been a visual confirmation of the unidentified beaked

Odontocete spatial patterns and temporal drivers of detection at sites in the Hawaiian islands

“…Risso's dolphins, Grampus griseus , Fraser's dolphin, Lagenodelphis hosei , Longman's beaked whales, Indopacetus pacificus , and killer whales, Orcinus orca , are also known to be present around the islands but likely represent a very small proportion of misclassifications due to low sighting rates near the HARP sites (Baird, Webster, et al, 2013). Some detections of beaked whales may also be misclassifications of an unidentified beaked whale species first detected at Cross Seamount, Hawai'i; this would be most likely at Kaua'i where this species has been acoustically recorded on the U.S. Pacific Missile Range Facility (PMRF; Manzano‐Roth et al, 2022).…”

Geographic distribution of the Cross Seamount beaked whale based on acoustic detections

“…This was done partly because there is no acoustic signature match for ginkgo-toothed beaked whales, and also due to the spatial overlap between the distribution of BWC-FM pulse acoustic detections and the limited sighting and stranding records of this species throughout the Pacific Ocean, especially around Japan (Nishiwaki & Kamiya, 1958). Due to the strongly nocturnal occurrence of the BWC-FM pulse, it has also been theorized that this pulse type is produced by a beaked whale species with a known signal type as a secondary acoustic signature (Manzano-Roth et al, 2023). For several reasons, this theory seems unlikely.…”

“…Blainville's and Cuvier's beaked whales are the only two species of beaked whales that have been acoustically detected over the entire geographic range of the BWC-FM pulse in the North Pacific Ocean (Keating et al, 2016(Keating et al, , 2018McCullough et al, 2021a,b;Simonis et al, 2020;Yano et al, 2018Yano et al, , 2020. Both species produce known FM pulse types with no diel patterning (Baumann-Pickering et al, 2014;Henderson et al 2016;Manzano-Roth et al, 2023;McCullough et al, 2021a).…”

“…A unique FM pulse type was first recorded near Cross Seamount in the Pacific Ocean south of Hawaii, with a linear frequency upsweep from 35 to 100 kHz, duration of 932 μs, and mean IPI of 0.14 s (McDonald et al 2009). This FM pulse type, called the BWC signal (Baumann‐Pickering et al, 2013), has been recorded in a number of tropical locations throughout the central and western Pacific Ocean (Baumann‐Pickering et al, 2014) and elsewhere in Hawaii (Manzano‐Roth et al, 2023), the Mariana Archipelago (McCullough et al, 2021b), and off Baja California, Mexico (Simonis et al, 2018), but has never been definitively linked to a known species. Its acoustic features are distinctive from other beaked whale signals due to the pulse's longer duration, shorter IPI, and extremely wide bandwidth.…”

“…Baumann‐Pickering et al (2014) hypothesized this FM pulse type might be produced by ginkgo‐toothed beaked whales ( Mesoplodon ginkgodens ) based on that species' tropical Pacific distribution. However, unlike all other beaked whale FM pulses, the BWC signal has largely been recorded only at night (Baumann‐Pickering et al, 2014; Manzano‐Roth et al, 2023), making a definitive link to a species difficult.…”