Understanding and mitigating human-made noise impacts on Southern Resident Killer Whales populations within the Salish Sea

New report released by NOAA Northwest Fisheries Science Center and PMEL

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.  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.