Acoustic detectability of whales amidst underwater noise off the west coast of South Africa

Shabangu, Fannie W.; Yemane, Dawit; Best, G. N.; Estabrook, Bobbi J.

doi:10.1016/j.marpolbul.2022.114122

Cited by 8 publications

(5 citation statements)

References 36 publications

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“… acc = 0.85 [28] RF, GLMs Whale calls collected between July 2014 and January 2017.

about 80% of acoustic detectability

[95] SVM, SMO 469 measurement points of urban soundscapes.

AUC = 0.913 [91] Transfer learning , CNNs , pseudo-labeling

700 sampling sites from 2016 to 2019 1-minute recording every 10 min.

…”

Section: Resultsmentioning

confidence: 99%

Systematic review of machine learning methods applied to ecoacoustics and soundscape monitoring

Nieto-Mora,

Rodríguez-Buritica,

Rodríguez-Marín

et al. 2023

Heliyon

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“… acc = 0.85 [28] RF, GLMs Whale calls collected between July 2014 and January 2017.

about 80% of acoustic detectability

[95] SVM, SMO 469 measurement points of urban soundscapes.

AUC = 0.913 [91] Transfer learning , CNNs , pseudo-labeling

700 sampling sites from 2016 to 2019 1-minute recording every 10 min.

…”

Section: Resultsmentioning

confidence: 99%

Systematic review of machine learning methods applied to ecoacoustics and soundscape monitoring

Nieto-Mora,

Rodríguez-Buritica,

Rodríguez-Marín

et al. 2023

Heliyon

View full text Add to dashboard Cite

“…However, detection rates for other species, such as dolphins, may decrease in elevated sea states. Shabangu et al (2022), for example, suggest that high wind speeds induce a decrease in cetacean acoustic detectability due to increased ambient noise. Such a large-scale survey targeting only sperm whales would therefore not be costeffective.…”

Section: Figurementioning

confidence: 99%

“…Poupard et al (2022) suggested that sperm whales do not come close to ships because ambient noise masks their echolocation when foraging. In addition, many studies have shown that cetaceans would modify their vocalisations in the vicinity of vessels and increase their sound level to maintain acoustic contact with other individuals (Castellote et al, 2012;Melcoń et al, 2012;Shabangu et al, 2022).…”

Section: Model Improvementmentioning

confidence: 99%

Summer distribution of the Mediterranean sperm whale: insights from the acoustic Accobams survey initiative

Lerebourg,

Boisseau,

Ridoux

et al. 2023

Front. Mar. Sci.

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The Mediterranean sperm whale population, Physeter macrocephalus, is listed as endangered due to population decline caused by human activities. To mitigate the impact of these activities, accurate knowledge of their distribution and abundance is crucial. During their long dives, sperm whales are not available to visual observation, but since they produce sounds when they dive, they are available to acoustic detection. Therefore, we aimed to use towed acoustic data to model their habitat and fill the knowledge gap on Mediterranean sperm whale distribution. Generalised additive models were used to link the number of sperm whales detected acoustically during the ACCOBAMS Survey Initiative in 2018 with different environmental variables integrated over different depth classes, encompassing the depth range used by the species for foraging. Sperm whale distribution was influenced by water temperature at the bottom, eddy kinetic energy between 200 and 600 m, as well as gradients of sea surface temperature and chlorophyll-a concentrations. The abundance of sperm whales was estimated at 2,959 individuals [2,077 - 4,265] in the sampled areas of the Mediterranean Sea. We predicted that sperm whales were mainly distributed in summer along the continental slope of the north-western Mediterranean basin from the Balearic Islands to the Ligurian Sea and off the Algerian coast. They were present throughout the western Mediterranean Sea and in the northern Ionian Sea. In contrast, predicted densities were low in the eastern part of the Mediterranean Sea. The use of acoustic data compensated for the main difficulty in studying sperm whales, the unavailability of animals at the surface during visual observation and the paucity of visual data. We thus encourage more systematic use of passive acoustics to study sperm whale distribution. The model highlighted a higher concentration of sperm whales in the western Mediterranean basin than in the eastern basin in summer, opening up avenues to improve the conservation of this endangered Mediterranean sub-population.

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“…These low wind speeds also matched the high numbers of killer whales observed from October to December [ 28 ]. High wind speeds are associated with high underwater noise that could have masked killer whale calls in winter as wind-induced noise dominates underwater noise levels above 500 Hz [ 75 ], and wind-induced air bubbles on the sea surface could have attenuated some of the acoustic energy of the calls hitting the sea surface [ 76 , 77 ]. The observed secondary high partial effect of high wind speed could be because the wind pattern for mid-2021 to mid-2022 was somewhat different to the climatological seasonal cycle (electronic supplementary material, figure S4b) and coincided with killer whale occurrence.…”

Section: Discussionmentioning

confidence: 99%

“…Wind speed was the most important predictor of the occurrence of both echolocation clicks and social calls as their occurrence in October to December coincided with low wind speed known for this area ([ 16 ]; electronic supplementary material, figure S4b). In addition, low wind speed would have improved the acoustic detectability of killer whale calls by our recorder and between individuals given the low ambient noise levels and increased the communication space between conspecifics at those wind speeds [ 43 , 75 ] and provided suitable habitat [ 9 ]. A combination of SSH, chlorophyll-a and SST were the moderately important predictors of the occurrence of echolocation clicks and social calls, a reflection of the importance of these variables at driving the ecology and foraging behaviour of killer whales in this region.…”

Section: Discussionmentioning

confidence: 99%

Killer whale acoustic patterns respond to prey abundance and environmental variability around the Prince Edward Islands, Southern Ocean

Shabangu,

Daniels,

Jordaan

et al. 2024

R. Soc. open sci.

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Killer whales are apex predators with temporally and spatially varying distributions throughout the world's oceans. Their ecology and behaviour are poorly understood in most regions due to limited research, often because of logistical challenges. Here, we used a passive acoustic monitoring device to investigate the seasonal acoustic occurrence and diel vocalizing behaviour of killer whales around the remote sub-Antarctic Prince Edward Islands (PEIs), Southern Ocean. Killer whales showed diel vocalizing patterns that varied seasonally in relation to their prey abundance and social activities. Killer whale calls were intermittently detected year-round with a high number of hours containing calls in October to December, and a secondary peak in February to May, corresponding to seal prey abundance. Random forest modelling identified wind speed as the primary predictor of the occurrence of killer whale calls (with a negative correlation) while sea surface height, chlorophyll-a and sea surface temperature were moderately important. We provide the first acoustic evidence that killer whale occurrence around the PEIs might coincide with variability in environmental conditions and prey abundance. Our results provide the first indication of diel vocalizing pattern of killer whales in the Southern Ocean. This knowledge is important for understanding killer whale ecology and adaptation to the changing oceans.

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Acoustic detectability of whales amidst underwater noise off the west coast of South Africa

Cited by 8 publications

References 36 publications

Systematic review of machine learning methods applied to ecoacoustics and soundscape monitoring

Systematic review of machine learning methods applied to ecoacoustics and soundscape monitoring

Summer distribution of the Mediterranean sperm whale: insights from the acoustic Accobams survey initiative

Killer whale acoustic patterns respond to prey abundance and environmental variability around the Prince Edward Islands, Southern Ocean

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