Application of Density Estimation Methods to Datasets from a Glider

Abstract

LONG-TERM GOALSThis is a new project that started in August 2013 and the long-term goal is to extend the use of population density estimation methods based on detections of marine mammal vocalizations to datasets collected by a moving platform. The moving platform under consideration is an electric underwater glider, which offers the potential of surveying a larger area than a fixed, single sensor. The glider also has the potential to surface and transmit data using a satellite modem. Moreover, fitting the glider with two hydrophones, one on each wing can provide bearings to vocalizing animals. Density estimation from glider datasets will be developed by looking at some of the species known to occur off the central Oregon coast, such as humpback and sperm whales as well as different dolphin species. OBJECTIVESThe objective of this research is to extend existing methods for cetacean population density estimation from fixed passive acoustic recordings to datasets recorded from a moving platform, in particular using an underwater glider. Instead of using datasets previously recorded for different applications, the current project will benefit from data collections designed specifically for density estimation purposes, with combined environmental sampling provided by the glider's Conductivity, Temperature and Depth (CTD) sensor. The central Oregon coast, where experiments and data collection will take place, is an easily accessible area for both project teams (PSU and OSU) working on this project with known occurrence of many marine mammal species, ranging from pinnipeds, to baleen whales, cetaceans and dolphin species (Carretta et al., 2009). Extensive oceanographic (Pierce et al., 2012) as well as noise characterization (Haxel et al., 2011) has also been performed in this area, providing possible support data for the current project's data analysis. Because gliders offer low-cost, all-weather, remote-area operation, it is our goal to extend its usability to population density estimation surveys offering another tool to aid those involved in marine mammal research, monitoring, and mitigation planners.