PMEL Publications Abstract
FY 2026
Underwater acoustic monitoring desktop study: A collaborative initiative between Port of Seattle (PoS) and National Oceanic and Atmospheric Administration (NOAA)
Holt, M.M., C.K. Emmons, R.P. Dziak, D.K. Mellinger, and S.M. Haver
NOAA Tech. Memo. NMFS-NWFSC 207, U.S. Department of Commerce, doi: 10.25923/g589-6539, Link to this report. (2026)
Underwater passive acoustics is a method of sensing or monitoring sounds generated in aquatic environments. Traditionally, hydrophones or underwater microphones are used for underwater acoustic monitoring. These passive acoustics approaches are widely used to listen for and detect marine animals who rely on hearing and sound to sense their environment, find food, navigate, and communicate with others in underwater habitats where vision is limited. Researchers use passive acoustic approaches to document the presence and seasonal habitat use of various marine mammals including killer whales, given their vociferous nature. They also use this approach to study sources of underwater noise, natural or otherwise, which are used to characterize acoustic habitats or soundscapes. Passive acoustics approaches can also augment visual sightings of animals and other ocean sound sources, especially in darkness and foul weather.
Since the 1970s, researchers have used passive acoustic approaches to document the presence of locally occurring killer whales in the Salish Sea ecosystem, including endangered Southern Resident killer whales. The Salish Sea consists of the transboundary inland waters of Washington State and southern British Columbia, Canada, and includes several international ports and commercial vessel traffic corridors. Southern Residents rely on sound for finding their fish prey and to communicate among group family members, and have designated critical habitat in the Salish Sea. Given growing concerns about disturbance effects of vessels and noise, several programs have formed that focus on monitoring and mitigating the impacts of maritime vessels operating in Southern Resident habitats.
Following a key recommendation to implement ship monitoring programs and noise-reduction initiatives within Washington State, the Quiet Sound program was formed in 2021. Quiet Sound aims to understand and mitigate the acoustic and physical impacts of large commercial vessels in Washington waters that overlap with Southern Resident critical habitat. Quiet Sound complements similar efforts of the ECHO program led by the Vancouver Fraser Port Authority in British Columbia that launched in 2014. Both programs implement seasonal slowdowns of commercial vessels and support acoustic monitoring programs in Southern Resident habitats.
This report summarizes past and present underwater acoustic monitoring efforts within the geographic area of the Quiet Sound program; identifies spatial and functional gaps in monitoring of Southern Resident killer whales, commercial vessel traffic, and associated noise; and provides recommendations for future acoustic monitoring to evaluate commercial vessel presence and noise and mitigate potential impacts on SRKW, their habitat, and ecosystems more fully.