Bottlenose Dolphin ( Tursiops truncatus) Whistle Modulation during a Trawl Bycatch Event in the Adriatic Sea

Marine mammal vocal elements have been investigated for decades to assess whether they correlate with stress levels or stress indicators. Due to their acoustic plasticity, the interpretation of dolphins' acoustic signals of has been studied most extensively. This work describes the acoustic par...

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Bibliographic Details
Published in:Animals (Basel) 2021-12, Vol.11 (12), p.3593
Main Authors: Corrias, Valentina, de Vincenzi, Giovanni, Ceraulo, Maria, Sciacca, Virginia, Sala, Antonello, de Lucia, Giuseppe Andrea, Filiciotto, Francesco
Format: Article
Language:English
Subjects:
acoustic communication
Acoustic properties
Acoustic tracking
Acoustics
Anthropogenic factors
Aquatic mammals
bottlenose dolphin
Bycatch
Caretta caretta
Case Report
Cetacea
Communication
Contours
Digital signal processors
Dolphins & porpoises
Economic impact
Fishing
Foraging behavior
Frequencies
International agreements
Marine mammals
Monitoring
Plastic properties
Plasticity
signature
Software
Stress
Trawling
Tursiops truncatus
Vocalization behavior
whistle
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Summary:Marine mammal vocal elements have been investigated for decades to assess whether they correlate with stress levels or stress indicators. Due to their acoustic plasticity, the interpretation of dolphins' acoustic signals of has been studied most extensively. This work describes the acoustic parameters detected in whistle spectral contours, collected using passive acoustic monitoring (PAM), in a bycatch event that involved three Bottlenose dolphins during midwater commercial trawling. The results indicate a total number of 23 upsweep whistles recorded during the bycatch event, that were analyzed based on the acoustic parameters as follows: (Median; 25th percentile; 75th percentile) D (second), total duration (1.09; 0.88; 1.24); f (HZ), minimum frequency (5836.4; 5635.3; 5967.1); f (HZ), maximum frequency, (11,610 ± 11,293; 11,810); f (HZ), central frequency; (8665.2; 8492.9; 8982.8); BW (HZ), bandwidth (5836.4; 5635.3; 5967.1); Step, number of step (5; 4; 6). Furthermore, our data show that vocal production during the capture event was characterized by an undescribed to date combination of two signals, an ascending whistle (upsweep), and a pulsed signal that we called "low-frequency signal" in the frequency band between 4.5 and 7 kHz. This capture event reveals a novel aspect of acoustic communication, it confirms their acoustic plasticity, and suggests that states of discomfort are conveyed through their acoustic repertoire.
ISSN:2076-2615
2076-2615
DOI:10.3390/ani11123593