Methodology and results of calibration of tonal click detectors for small odontocetes (C-PODs)

Dähne, Michael; Verfuß, Ursula K.; Brandecker, Anja; Siebert, Ursula; Benke, Harald

doi:10.1121/1.4816578

Cited by 32 publications

(26 citation statements)

References 23 publications

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“…The C-POD is a stationary autonomous data logger designed to passively detect cetacean echolocation clicks within the frequency range 20-170 kHz (www.chelonia.co.uk) and has been used in numerous studies on harbour porpoise distribution (e.g. Dähne et al, 2013a;Hardy et al, 2012). The C-POD uses online digital waveform characterization to register click events and their time of occurrence, intensity, envelope centre frequency and bandwidth.…”

Section: Static Acoustic Monitoringmentioning

confidence: 99%

Defining management units for cetaceans by combining genetics, morphology, acoustics and satellite tracking

Sveegaard

Galatius

Dietz

et al. 2015

Global Ecology and Conservation

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a b s t r a c tManaging animal units is essential in biological conservation and requires spatial and temporal identification of such units. Since even neighbouring populations often have different conservation status and face different levels of anthropogenic pressure, detailed knowledge of population structure, seasonal range and overlap with animals from neighbouring populations is required to manage each unit separately. Previous studies on genetic structure and morphologic separation suggests three distinct populations of harbour porpoises with limited geographic overlap in the North Sea (NS), the Belt Sea (BS) and the Baltic Proper (BP) region. In this study, we aim to identify a management unit for the BS population of harbour porpoises. We use Argos satellite data and genetics from biopsies of tagged harbour porpoises as well as acoustic data from 40 passive acoustic data loggers to determine management areas with the least overlap between populations and thus the least error when abundance and population status is estimated. Discriminant analysis of the satellite tracking data from the BS and NS populations showed that the best fit of the management unit border during the summer months was an east-west line from Denmark to Sweden at latitude 56.95°N. For the border between BS and BP, satellite tracking data indicate a sharp decline in population density at 13.5°E, with 90% of the locations being west of this line. This was supported by the acoustic data with the average daily detection rate being 27.5 times higher west of 13.5°E as compared to east of 13.5°E. By using this novel multidisciplinary approach, we defined a management unit for the BS harbour porpoise population. We recommend that these boundaries are used for future monitoring efforts of this population under the EU directives. The boundaries may also be used for conservation efforts during the summer months, while seasonal movements of harbour porpoises should be considered during winter.

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Section: Static Acoustic Monitoringmentioning

confidence: 99%

Defining management units for cetaceans by combining genetics, morphology, acoustics and satellite tracking

Sveegaard

Galatius

Dietz

et al. 2015

Global Ecology and Conservation

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“…Carstensen et al 2006) and also to quantify displacement of porpoises by pile-driving noise , Brandt et al 2011, Dähne et al 2013a). Individual C-PODs were calibrated prior to first deployment (Dähne et al 2013b). Standard settings provided by the manufacturer were used, and off-line analysis was performed with the KERNO classifier (C-POD.exe version 2.043).…”

Section: Stationary Acoustic Monitoringmentioning

confidence: 99%

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Dähne¹,

Tougaard²,

Carstensen³

et al. 2017

Mar. Ecol. Prog. Ser.

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Effects of constructing the DanTysk offshore wind farm (German Bight, 80 turbines, 6 m diameter foundations) were studied by passive acoustic monitoring of pile-driving noise and harbour porpoise Phocoena phocoena echolocation. An acoustic deterrence device (seal scarer) was used to protect porpoises from hearing loss and bubble curtains were used to attenuate the pile-driving noise. Porpoise occurrence, quantified by echolocation signals, decreased when the seal scarer was engaged, during pile driving and up to 5 h after pile driving stopped. This effect extended out to 12 km, less than the 18−25 km reported from other pile drivings performed without bubble curtains. The bubble curtains thus effectively reduced the temporary habitat loss and risk of hearing loss. The 2 bubble curtains each attenuated the noise by between 7 and 10 dB, when used separately, and 12 dB when used together. Attenuation was most pronounced above 1 kHz, where the pile-driving noise at larger distances was comparable to or lower than ambient noise. This suggests that noise regulation should be based on frequency-weighted sound levels in addition to broadband levels, to assure that mitigation measures are effective in reducing impact on animals and not only in fulfilling legal requirements. The strong reaction to the seal scarer raises concern that it may surpass the reactions to the pile-driving noise itself, when operating with bubble curtains, and calls for a re-evaluation of the specifications of seal scarer sounds.

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“…This equipment has been extensively used in field studies (Verfuss et al, 2007;Philpott et al, 2007;Todd et al, 2009;Dahne et al, 2013). T-POD and C-POD are efficient systems for long-term fixed operations.…”

Section: Introductionmentioning

confidence: 99%

Acoustic discrimination between harbor porpoises and delphinids by using a simple two-band comparison

Kameyama

Akamatsu

Dede

et al. 2014

The Journal of the Acoustical Society of America

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A simple discrimination method between Delphinidae and Phocoenidae based on the comparison of the intensity ratios of two band frequencies (130 and 70 kHz) is proposed. Biosonar signals were recorded at the Istanbul Strait (Bosphorus) in Turkey. Simultaneously, the presence of the species was confirmed by visual observation. Two types of thresholds of two-band intensity ratios, fixed and dynamic threshold, were tested for identification. The correct detection and false alarm rates for porpoises were 0.55 and 0.06 by using the fixed threshold and 0.74 and 0.08 by using the dynamic threshold, respectively. When the dynamic threshold was employed, the appropriate threshold changed depending on the mix ratio of recorded sounds from both Delphinidae and Phocoenidae. Even under biased mix ratios from 26% to 82%, the dynamic threshold worked with >0.80 correct detection and <0.20 false alarm rates, whereas the fixed threshold did not. The proposed method is simple but quantitative, which can be applicable for any broadband recording system, including a single hydrophone with two frequency band detectors.

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Methodology and results of calibration of tonal click detectors for small odontocetes (C-PODs)

Cited by 32 publications

References 23 publications

Defining management units for cetaceans by combining genetics, morphology, acoustics and satellite tracking

Defining management units for cetaceans by combining genetics, morphology, acoustics and satellite tracking

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Acoustic discrimination between harbor porpoises and delphinids by using a simple two-band comparison

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