Effect of Broadband Nature of Marine Mammal Echolocation Clicks on Click-Based Population Density Estimates [report]

Michael Ainslie
2014 unpublished
Award Number: N000141410409 https://www.tno.nl/ LONG-TERM GOALS The long-term aim of the project is to support passive acoustic monitoring (PAM) of Odontecetes. OBJECTIVES This project aims to demonstrate how the detection process of broadband clicks can be modeled for different marine mammal species and assess the magnitude of error on the estimated density due to various commonly used simplifying assumptions. Our main purposes are to quantify the bias in the population density estimate for
more » ... ected species and detector due to use of the narrow band approximation in the computed propagation loss, and to understand the factors affecting the magnitude of this bias to enable extrapolation to other species and detectors. Technical approach: This project is in collaboration between TNO (PI: Michael Ainslie) with the University of St. Andrews (grant number: N000141410396, PI: Len Thomas). Detectability of a broadband echolocation click is quantified by synthesizing pressure time series separately for noise f N (t), signal f S (t;r), and signal plus noise f S+N (t; r) = f S (t;r) + f N (t) (as illustrated in Figure 1 ). As a basis for the source echolocation clicks we intend to use recordings of echolocation clicks obtained nearby to the species considered in this study. These recorded source clicks are used to synthesize the corresponding echolocation clicks at the different ranges of interest, accounting for the effects of frequency dependent absorption on both propagation loss and detector performance. The resulting modeled received signal + noise are then fed through various detectors, thus enabling a highfidelity estimation of the detection probability without recourse to the sonar equation. The detection probability will be established by repeating the process for multiple realizations of the noise.
doi:10.21236/ada616461 fatcat:rw4qpusyjvedxnv3gtf63kxm4q