Passive acoustic monitoring (PAM) is a valuable tool for studying habitat use patterns of cetaceans, often broadening the spatial and temporal scope of traditional visual survey effort. For endangered populations, understanding habitat use is critical for effective conservation and management, as increasing anthropogenic pressures may alter residency and occurrence. Here, we analyse near-continuous, multi-year PAM data to assess summer presence and residency patterns of the endangered southern resident killer whale population (SRKW; Orcinus orca ater) in Canadian Pacific waters. Acoustic data were collected over a 6-month period (1 May–31 Oct) across 3 years (2018–2020) at Swiftsure Bank and in the Strait of Juan de Fuca, with recorders positioned off Port Renfrew, Jordan River and Sooke. Seasonal acoustic occurrence of SRKW was markedly higher at Swiftsure Bank and Port Renfrew compared to the other sites, with a pronounced peak in acoustic presence in August. Diel detection of SRKW differed among sites, with lower call detection at dawn and higher detections at dusk at Swiftsure Bank, but no discernible diel patterns at Sooke. These findings improve our understanding of SRKW summer habitat use patterns within part of their critical habitat and highlight methodological considerations for optimising PAM deployments and post-processing procedures.
Southern resident killer whale, passive acoustic monitoring, acoustic detection, habitat use, critical habitat