Passive acoustic monitoring of Southern Resident Killer Whales: Occurrence, residency and movement data in support of conservation

Abstract

Passive acoustic monitoring (PAM) of cetaceans offers valuable spatio-temporal information on presence and residency time to support population management and recovery strategies. Acoustic detections can be used to evaluate diel and seasonal occurrence patterns when visual detection opportunities are limited (e.g., night or winter), and acoustic encounter duration can inform habitat use patterns (e.g., travelling/shorter duration vs foraging/longer duration). Additionally, detection data from strategically placed recorders may also be used in the development of predictive movement models. Here we use PAM data to evaluate critical habitat use by the Endangered Southern Resident Killer Whale (SRKW) population in Juan de Fuca Strait and the Salish Sea, near the southwest coast of Vancouver Island, British Columbia. Continuous recordings were collected at three locations from May to October, 2018–2020, and used to assess presence and acoustic encounter duration. As this area experiences significant commercial vessel traffic and recreational vessel use, mitigation of risk from acoustic disturbance is a high priority for recovery. These PAM detection and encounter duration data were used to provide advice for management actions in support of SRKW recovery in Canadian Pacific waters.