oa Passive Acoustic Monitoring of Australia’s Offshore Waters via Distributed Acoustic Sensing

Distributed acoustic sensing (DAS) has been extensively researched, tested, and implemented for geophysical monitoring on land over the past decade. Recently, DAS researchers have turned their attention to submarine telecommunications fibre-optic cables (FOCs) laid across the ocean floor.

Developments in DAS interrogator units (IUs) capable of sensing over long (100 km or more) telecommunications cables have created opportunities for underwater passive acoustic monitoring (PAM) using existing subsea infrastructure. Over the past few years, several research groups have conducted DAS trials with submarine cables for geophysical imaging, microseism monitoring, and acoustic monitoring of sounds produced by marine vessels and low-frequency marine fauna ( Lindsey et al., 2019 ; Bouffaut et al., 2022 ; Wilcock et al., 2023 ; Debens et al., 2024 ). Despite extensive ongoing research into underwater DAS, there is still limited understanding of the response of DAS to changes in sound pressure and its efficient use underwater.

We present a proof-of-concept study of DAS for PAM conducted on the North West Shelf of Western Australia. During this trial, a continuous 2-month DAS dataset was recorded. We present the results of DAS data analyses and event detection, and a comparison of subsea DAS to seabed hydrophone data.