Validating acoustic monitors for marine animals: Field experience with beaked whales and digital acoustic monitors (DMONs).

Abstract

Passive acoustic monitoring (PAM) is a promising tool for improving the effectiveness of visual surveys for marine animals and for stand‐alone persistent monitoring. Nonetheless, significant data gaps make it difficult to predict PAM performance for many species. Detection functions are only beginning to be formed for some vocalizations and detectors. Statistical models for calling rates, as a function of behavior, are needed to translate acoustic detections into abundance estimates, or lack of detections into decisions about absence of animals. Finally, ambient noise levels and spectra are unavailable in most of the world’s oceans, complicating the application of results from one area to another. Although some of these gaps are being addressed by a growing group of researchers, there is an urgent need to develop standards for measuring and reporting results, and to foster the interchange of data. To exemplify the form such standards might take, and the potential pitfalls, we present results from a series of field experiments designed to assess the performance of an acoustic monitor for beaked whales. The experiments made use of a freely available reference design for an acoustic detector, called the DMON, which may provide a basis for standardizing and validating real‐time implementations.