U.S. Navy application and interest in passive acoustics for estimation of marine mammal population density

Abstract

Marine species population density estimation from passive acoustic monitoring is an emergent topic of interest to the U.S. Navy. Density estimates are used by the Navy and other Federal partners in effects modeling for environmental compliance documentation. Current traditional methods of marine mammal density estimation via visual line transect surveys require expensive ship time and long days at-sea for an experienced crew to yield limited spatial and temporal coverage. While visual surveys remain an effective means of deriving density estimates, passive acoustic based density estimation methods have the unique ability to improve on visual density estimates for some key species by: (a) expanding spatial and temporal density coverage, (b) providing coverage in areas too remote or difficult for traditional visual surveys, (c) reduce the statistical uncertainty of a given density estimate, and (d) providing estimates for species that are difficult to survey visually (e.g., minke and beaked whales). The U.S. Navy has invested in research for the development, refinement, and scientific validation of passive acoustic methods for cost effective density estimates in the future. The value, importance, and current development in passive acoustic-based density estimation methods for Navy applications will be discussed.