An Industry Perspective of Using Towed Passive Acoustic Monitoring (PAM) for the Detection of Marine Mammals at Sea During Seismic Surveys.

Abstract

Abstract Visual monitoring has been the primary method of detecting marine mammals during offshore operations for many years. The effectiveness of visual detection is reduced however, when animals are not at the surface and during periods of poor visibility. Towed passive acoustic monitoring (PAM) offers an opportunity to detect and indicate the location of marine mammal vocalisations relative to a hydrophone streamer being towed from a moving vessel. Vocalising marine mammal species may be identified by the characteristics of their calls and sonar clicks. Though basic automatic detection and species recognition functionality may be available, experienced and specialised operators are required to maximise detection/identification efficiency and minimise the likelihood of false detections. PAM is becoming an increasingly important monitoring tool during marine mammal population studies. When used as a monitoring tool in conjunction with mitigation measures, PAM provides the potential to reduce the risk of impacts from human activities on marine mammals. Though considered particularly useful for monitoring during periods of poor visibility, current towed PAM technology requires further development and field testing in order to provide a consistent and reliable real-time monitoring tool at sea. There is increased regulatory interest in using PAM as a means of monitoring marine mammals at sea during seismic survey operations at night or during periods of low visibility. As with any new technology, there is a need to ensure that both capabilities and limitations of the method during real-time Industry conditions are understood before requiring its use as a monitoring tool. Lessons learned from industry experience using PAM systems in the field will increase the understanding of current capabilities and limitations and will lead to further improvement of the technology. Recent experience of deploying towed PAM systems and testing a new; standardised user interface under real-time industry conditions, has identified some practical challenges of using PAM as a mitigation monitoring tool during offshore operations.