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

Fannie W Shabangu; Dawit Yemane; George Best; Bobbi J Estabrook

doi:10.1016/j.marpolbul.2022.114122

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

Mar Pollut Bull. 2022 Nov:184:114122. doi: 10.1016/j.marpolbul.2022.114122. Epub 2022 Sep 22.

Authors

Fannie W Shabangu¹, Dawit Yemane², George Best³, Bobbi J Estabrook⁴

Affiliations

¹ Fisheries Management Branch, Department of Forestry, Fisheries and the Environment, Foreshore, Cape Town, South Africa; Mammal Research Institute Whale Unit, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa. Electronic address: fannie.shabangu@yahoo.com.
² Fisheries Management Branch, Department of Forestry, Fisheries and the Environment, Foreshore, Cape Town, South Africa; Department of Biological Sciences and Marine Research Institute, University of Cape Town, Cape Town, South Africa.
³ ORBCOMM, Apartado Correos 128 Port de Pollensa, Balearics 07470, Spain.
⁴ K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA.

PMID: 36155414
DOI: 10.1016/j.marpolbul.2022.114122

Abstract

Anthropogenic underwater noise has been shown to negatively affect marine organisms globally; yet little to no noise research has been conducted in most African waters including South Africa's. This study aimed to quantitatively describe sources of underwater noise and effects of underwater noise on the acoustic detectability of Antarctic blue, fin, minke, humpback, and sperm whales off South Africa's west coast. Noise from vessel traffic (<35 km to the location of recorders) dominated the soundscape below 500 Hz while wind-generated noise increased with wind speed above 5 m s^-1 and dominated the soundscape above 500 Hz. Acoustic detectability of humpback, minke and sperm whales decreased with increasing ambient noise levels whereas blue and fin whale acoustic detectability increased with the ambient noise levels. We provide baseline information on underwater noise sources and the effects of underwater noise on whale acoustic detectability off the west coast of South Africa.

Keywords: Long-term trends; Noise pollution; Ocean economy; Oceanographic conditions; Underwater noise; Vessel traffic.

MeSH terms

Acoustics
Animals
Fin Whale*
Noise
South Africa
Whales*