An autonomous hydrophone array to study the acoustic ecology of deep-water toothed whales

Malinka, Chloe; Atkins, John Alfred; Johnson, Mark; Tønnesen, Pernille; Dunn, Charlotte; Claridge, Diane; Soto, Natacha Aguilar de; Madsen, Peter T.

doi:10.1016/j.dsr.2020.103233

Cited by 13 publications

(10 citation statements)

References 62 publications

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“…Knowledge of the beam profile is also a factor when designing hydrophone arrays to localises and provide acoustic quantifications for different species (e.g. Zimmer et al, 2008;Malinka et al, 2020). 3D 360 beam profile manuscript last updated 04/May/2020 6 The potential importance of beam profiles, both in understanding the sensory ecology of animals and for informing PAM, has prompted several studies on the wider radiation of sound around toothed whales.…”

Section: Introductionmentioning

confidence: 99%

High resolution three-dimensional beam radiation pattern of harbour porpoise clicks with implications for passive acoustic monitoring

Macaulay

Malinka

Gillespie

et al. 2020

The Journal of the Acoustical Society of America

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The source properties and radiation patterns of animal vocalisations define, along with propagation and noise conditions, the active space in which they can be detected by conspecifics, predators, prey and by passive acoustic monitoring (PAM). Here we report the 4π (360° horizontal and vertical) beam profile of a freeswimming, trained harbour porpoise measured using a 27-element hydrophone array. The forward echolocation beam is highly directional, as predicted by a piston model, and is consistent with previous measurements. However, at off-axis angles greater than ±30°, the beam attenuates more rapidly than the piston model and no side lobes are present. A diffuse back beam is also present with levels about-30 dB relative to the source level. In PAM, up to 50% of detections can be from portions of the beam profile with distorted click spectra, although this drops substantially for higher detection thresholds. Simulations of the probability of acoustically detecting a harbour porpoise show that a traditional piston model can underestimate the probability of detection compared to the actual 3D radiation pattern documented here. This highlights the importance of empirical 4π measurements of beam profiles of toothed whales, both to improve understanding of their biology and to inform PAM.

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Section: Introductionmentioning

confidence: 99%

High resolution three-dimensional beam radiation pattern of harbour porpoise clicks with implications for passive acoustic monitoring

Macaulay

Malinka

Gillespie

et al. 2020

The Journal of the Acoustical Society of America

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“…Array recordings were made using two custom-built vertical hydrophone arrays, each composed of seven autonomously recording and sample-synchronized SoundTraps (ST300-HF, Ocean Instruments, Auckland, New Zealand; http://www.oceaninstruments.co.nz/) (see Malinka et al, 2020). The SoundTraps were spaced ∼14 m apart (13.82-14.21 m), as informed by simulations of predicted Kogia beam patterns, for an overall aperture of 84 m. Animals can theoretically be localized (with less than 30% range error) out to ∼840 m around the array (10× the array aperture), based on increasing deterioration in localization accuracy with increasing range (e.g.…”

Section: Recording and Calibrationmentioning

confidence: 99%

“…The SoundTraps were spaced ∼14 m apart (13.82-14.21 m), as informed by simulations of predicted Kogia beam patterns, for an overall aperture of 84 m. Animals can theoretically be localized (with less than 30% range error) out to ∼840 m around the array (10× the array aperture), based on increasing deterioration in localization accuracy with increasing range (e.g. Kyhn et al, 2009;Macaulay et al, 2017;Malinka et al, 2020).…”

Section: Recording and Calibrationmentioning

confidence: 99%

Echolocation click parameters and biosonar behaviour of the dwarf sperm whale (Kogia sima)

Malinka

Tønnesen

Dunn

et al. 2021

Journal of Experimental Biology

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Dwarf sperm whales (Kogia sima) are small toothed whales that produce narrow-band high-frequency (NBHF) echolocation clicks. Such NBHF clicks, subject to high levels of acoustic absorption, are usually produced by small, shallow-diving odontocetes, such as porpoises, in keeping with their short-range echolocation and fast click rates. Here, we sought to address the problem of how the little-studied and deep-diving Kogia can hunt with NBHF clicks in the deep sea. Specifically, we tested the hypotheses that Kogia produce NBHF clicks with longer inter-click intervals (ICIs), higher directionality and higher source levels (SLs) compared with other NBHF species. We did this by deploying an autonomous deep-water vertical hydrophone array in the Bahamas, where no other NBHF species are present, and by taking opportunistic recordings of a close-range Kogia sima in a South African harbour. Parameters from on-axis clicks (n=46) in the deep revealed very narrow-band clicks (root mean squared bandwidth, BWRMS, of 3±1 kHz), with SLs of up to 197 dB re. 1 µPa peak-to-peak (μPapp) at 1 m, and a half-power beamwidth of 8.8 deg. Their ICIs (mode of 245 ms) were much longer than those of porpoises (<100 ms), suggesting an inspection range that is longer than detection ranges of single prey, perhaps to facilitate auditory streaming of a complex echo scene. On-axis clicks in the shallow harbour (n=870) had ICIs and SLs in keeping with source parameters of other NBHF cetaceans. Thus, in the deep, dwarf sperm whales use a directional, but short-range echolocation system with moderate SLs, suggesting a reliable mesopelagic prey habitat.

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“…They drift slowly, providing the opportunity to capture a full beaked whale or Kogia spp. dive cycle; and drift freely with ocean currents providing sampling opportunities across diverse habitats without potential bias that can arise from a priori decisions about monitoring locations (Griffiths and Barlow, 2016;Keating et al, 2018;Fregosi et al, 2020;Malinka et al, 2020). In addition, the slow drift rate and reduced noise levels allow for increased opportunities to detect the short wavelength and highly directional NBHF clicks produced by Kogia spp.…”

Section: Introductionmentioning

confidence: 99%

An Acoustic Survey of Beaked Whales and Kogia spp. in the Mariana Archipelago Using Drifting Recorders

et al. 2021

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The distribution, abundance, and habitat of cryptic cetacean species such as beaked whales and dwarf/pygmy sperm whales (Kogia spp.) are challenging to study due to their long dive times and/or very limited surface behavior. Even less is known in minimally studied and remote regions, including the Mariana Archipelago and parts of the broader western Pacific. In 2018, we deployed a network of eight Drifting Acoustic Spar Buoy Recorders (DASBRs) on the west side of the Mariana Archipelago with the goal of examining the distribution and habitat of beaked whales and Kogia spp. in this region using passive acoustic monitoring. Concurrently, conductivity-temperature-depth (CTD) data were collected within the drift area and combined with satellite oceanographic data to build Ensemble Random Forest Models to identify specific oceanographic features that determine the distribution of these species. DASBRs deployed at locations ranging from 13°N to 18°N generally drifted from east to west between the Mariana Archipelago and the West Mariana Ridge. Spectral and temporal characteristics of echolocation signals were used to identify the presence of beaked whales and Kogia spp. species. This dataset contained frequency modulated (FM) pulses characteristic of Longman’s (Indopacetus pacificus), Cuvier’s (Ziphius cavirostris), and Blainville’s (Mesoplodon densirostris) beaked whales, as well as the unidentified beaked whale FM pulse known as the “BWC,” along with narrow-band high frequency clicks from Kogia spp. The detection rate was substantially higher for all species on the five tracks in the region north of 15.5°N than for those drifts occurring farther south. Species distribution models suggest that differences in the oceanographic characteristics between the northern and southern regions may impact foraging opportunities, possibly explaining the specific ecological niche for these species within this water mass. This is the first study of the distribution of cryptic cetacean species within the wider Mariana Archipelago region. We demonstrate that autonomous drifting acoustic recorders, combined with environmental sampling and remote satellite data are a powerful tool for studying the habitat dependent distribution of cryptic cetacean species.

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An autonomous hydrophone array to study the acoustic ecology of deep-water toothed whales

Cited by 13 publications

References 62 publications

High resolution three-dimensional beam radiation pattern of harbour porpoise clicks with implications for passive acoustic monitoring

High resolution three-dimensional beam radiation pattern of harbour porpoise clicks with implications for passive acoustic monitoring

Echolocation click parameters and biosonar behaviour of the dwarf sperm whale (Kogia sima)

An Acoustic Survey of Beaked Whales and Kogia spp. in the Mariana Archipelago Using Drifting Recorders

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