Abstract
Near real-time mitigation monitoring using passive acoustics is increasingly required for marine mammals surrounding industrial activities in the ocean. Furthermore, it is beneficial to understand not just whether marine mammals are present, but also where marine mammals are with respect to a given mitigation zone, to both minimize potential adverse impacts on the species of concern and determine what level of mitigation, if any, is required for the development activity. In response to this, SMRU Consulting developed a multi-channel autonomous passive acoustic monitoring system: the CAB (Communications Acoustic Buoy). Here, three case studies are presented. (1) Pile driving: CABs were used to assess the extent of the modelled exclusion zone by providing real-time field measurements to expedite pile-driving construction and optimize bubble curtain mitigation efficacy. (2) Offshore wind: a playback study demonstrated that real-time whale localization information reduced delays in construction brought about by unrequired mitigative shutdowns, compared to non-bearing PAM systems. (3) Dredging: CABs successfully detected dolphins during dredging and spoil disposal to meet regulatory requirements alongside a port redevelopment. Across applications, CAB uptime exceeded 98% and the latency of audio clips, noise measurements, and detections were 95% <1.6 s, highlighting that near real-time PAM represents a powerful tool to reduce costs whilst enhancing regulatory compliance.