A comparison of ranging methods using Ocean Bottom Seismometers
Abstract
Estimating marine mammal abundance or density is a central component of marine mammal monitoring programs, including those undertake n by the Navy. Accurate estimates of the number of animals in an area of interest are essential for predicting the potential impacts of anthropogenic activity on marine mammal populations. Monitoring programs to determine marine mammal densities are costly, so the re is interest in investigating alternative surveying and analytical methods that allow monitoring programs to be cost efficient yet robust. One such approach is to use data from instrumentation deployed for other purposes. Ocean bottom seismometers (OBSs) and the Comprehensive Nuclear Test Ban Treaty Organization International Monitoring System (CTBTO IMS) are prime examples of such platform s of opportunity. Many hundreds of OBSs are used by the global academic community and they are being deployed increasingly often in large arrays for periods of a year or more. Modest networks of permanent OBSs have also been deployed on cabled observatories in a few regions such as offshore Japan and the Pacific Northwest. The experiment sites often fall in areas of research interest for ba leen whales, specifically blue and fin whales, which call below the typical 25 100 Hz upper frequency limit of many OBSs (though OBS s with higher sampling rates also exist with the potential to monitor a broader range of marine mammal species e.g. Auffret et al., 2004). These instruments have been successfully used to detect and track both species using the arrival times of calls at multiple s ensors (e.g., Soule & Wilcock, 2013; Wilcock et al., 2015). Furthermore, for fin whales methods have been developed to range calls w ith a single OBS (Matias & Harris, 2015; Weirathmueller et al., 2017). The tracking and ranging data can then be used in analyses to estimate the density of animals around the OBSs. To date, traditional density estimation methods have been applied to data from OBS s (Harris et al., 2013) and novel density estimation methods have been developed using OBS data (Mellinger et al., 2015, Harris et a l., 2018). However, while these studies have demonstrated the utility of OBS data, the signal processing techniques have not yet bee n developed to the point where they can be routinely applied by the wider research community.In this project, we propose to build on previous ONR grants held by the prime offeror and subcontracted institutions (N00014-14-1-0423 Multipath ranging and blue whale tr acking algorithm; N00014-08-1-0523 Fin whale tracking and preliminary multipath ranging, N00014-11-1-0615 Cheap DECAF: Density e stimation for cetaceans from acoustic fixed sensors using separate, non-linked devices and N00014-16-1-2860/ N00014-16-1-2364 Larg e Scale Density Estimation of Blue and Fin Whales) to focus on ranging i.e., determining the range (distance) to a calling animal. Ranging is a key element of many density estimation methods. Here we propose to perform a comparison of ranging methods using OBS data, including a variety of instrument configurations and acoustic propagation conditions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 07, 2021
- Source ID
- N000142112564
Entities
People
- Danielle Harris
Organizations
- Office of Naval Research
- United States Navy
- University of St Andrews