Evaluation of a coastal acoustic buoy for cetacean detections, bearing accuracy and exclusion zone monitoring

• Published in: Methods in Ecology and Evolution
• Main Authors: Palmer, Kaitlin J., Tabbutt, Sam, Gillespie, Douglas, Turner, Jesse, King, Paul, Tollit, Dominic, Thompson, Jessica, Wood, Jason
• Other Authors: University of St Andrews. SMRU Consulting, University of St Andrews. School of Biology, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Sound Tags Group, University of St Andrews. Bioacoustics group, University of St Andrews. Marine Alliance for Science & Technology Scotland
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Acoustics; Autonomous; Conservation; Exclusion zone; Localization; Mitigation; Real-time; Whale; GC Oceanography; Ecology; Evolution; Behavior and Systematics; Ecological Modelling; DAS; SDG 14 - Life Below Water; GC; North Atlantic
• Online Access: http://hdl.handle.net/10023/26031; https://doi.org/10.1111/2041-210X.13973

The Maryland Department of Natural Resources and the Maryland Offshore Wind Development Fund at the Maryland Energy Administration cosponsored this work. This report was prepared as an account of work sponsored by an agency of the United States Government. There is strong socio-political support for offshore wind development in US territorial waters and construction is planned off several east coast states. Some of the planned development sites coincide with important habitat for critically endangered North Atlantic right whales. Both exclusion zones and passive acoustic monitoring are important tools for managing interactions between marine mammals and human activities. Understanding where animals are with respect to exclusion zones is important to avoid costly construction delays while minimizing the potential for negative impacts. Impact piling from construction of hundreds of offshore wind turbines likely require exclusion zones as large as 10 km. We have developed a three-hydrophone passive acoustic monitoring system that provides bearing information along with marine mammal detections to allow for informed management decisions in real-time. Multiple units form a monitoring system designed to determine whether marine mammal calls originate from inside or outside of an exclusion zone. In October 2021, we undertook a full system validation, with a focus on evaluating the detection range and bearing accuracy of the system with respect to right whale upcalls. Five units were deployed in Mid-Atlantic waters and we played more than 3500 simulated right whale upcalls at known locations to characterize the detection function and bearing accuracy of each unit. The modelled results of the detection function error were then used to compare the effectiveness of a bearing-based system to a single sensor that can only detect a signal but not ascertain directivity. Field trials indicated maximum detection ranges from 4-7.3 km depending on source and ambient noise levels. Simulations showed that incorporating bearing ...