Does depth matter Examining factors that could influence the acoustic identification of odontocete species on bottom-moored recorders
Abstract
Project Summary Passive acoustic monitoring is used extensively to collect information about marine mammal occurrence, distribution and behavior in areas with high Naval activity, and mitigation efforts rely heavily on data obtained by seafloor recorders. Substantial advancements have been made in the identification of odontocete species based on the properties of their whistles and clicks. However, the suitability of species classifiers trained using surface data for analyzing recordings obtained at depth is currently unknown. As a result, it remains unclear how depth, distance of animals from the recorder and sound propagation influence classification results. Here we propose to examine how species-?specific signaling cues are affected by these factors. We will use both surface-?deployed and bottom-?moored vertical arrays of hydrophones and autonomous recorders to obtain data from a variety of odontocete species at different points in the water column. We will use localization and sound propagation modeling to address the following questions: Does the depth at which dolphin whistles are recorded affect the signal properties observed? If so, does the performance of species classifiers developed using whistles recorded at the surface change when applied to data from bottom-?moored recorders? Do reported species-?specific click characteristics remain consistent across recording depths? If they do, are the cues consistent across behaviors, such as diving, surface milling and travel? We propose to conduct a two-?year effort to examine these questions. During the first year, the required vertical arrays will be assembled and field-?tested off Maui, Hawaii. During the second year, two 14-?day data collection periods will be executed off Kona, Hawaii and San Diego, California targeting a variety of odontocete species typically identified using whistle classifiers or click characteristics. The data obtain from both arrays will be used to examine signal characteristics, localize signalers and model signal propagation between the source and the recorder. The data will also be used to test the performance of existing whistle classifiers with signals obtained at different depths. In addition, a controlled experiment will be conducted with a trained dolphin from the Navy’s Marine Mammal Program to examine the propagation characteristics of whistles in an open water environment. It is expected that the results of this effort will provide a better understanding of the methods presently being employed for marine mammal monitoring and mitigation, and will lead to greater confidence in their application.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512373
Entities
People
- Marc Lammers
Organizations
- Oceanwide Science Institute
- Office of Naval Research
- United States Navy