Achieving consensus and convergence on a towed array passive acoustic monitoring standard for marine mammal monitoring

Towed passive acoustic monitoring (PAM) arrays from surface vessels has become a mature technology for marine mammal monitoring during marine seismic surveys. Multiple U.S. federal agencies have expressed a desire for consistent standards when implementing towed PAM. Two workshops involving academics, commercial PAM operators, and regulators have led to a comprehensive outline for an ASA towed array draft standard that covers requirements for initial operation planning, hardware, real-time monitoring and data acquisition, localization procedures, and post-operation validation. It does not cover operational mitigation decision criteria (such as power-down and/or shutdown of seismic airgun arrays), sound source verification, or how to initially establish the required detection range of the system. The standard’s fundamental goal is to reduce situations where background noise levels (arising from a variety of mechanisms) prevent effective PAM, and the dominant strategy employed is to standardize how acoustic measurements are logged, reported, and evaluated. Standardized plots would permit a non-technical supervisor or regulator to easily determine whether the PAM operation was self-noise limited under multiple operational circumstances. The approach taken here can serve as a template for future PAM standards for other deployment platforms [Work sponsored by BSSE and ONR Living Marine Resources Program.]