Improving estimates of Cuviers beaked whale sonar response by linking satellite tag and range acoustic data
Abstract
The goal of this project is to enhance our understanding of the population-level responses of Cuviers beaked whales to Navy sonar. We propose to use innovative statistical models to link available tag data with acoustic data collected on a US training range hydrophone array (SOAR) in Southern California to give us an improved picture of individual and population level movements. This will be combined with information about sonar usage so we can discover how these movements change when sonar is present.Cuviers beaked whales have been shown to respond to Navy sonar in a variety of ways, including changing their diving pattern, moving away from the sonar source and ceasing echolocation (which is used to locate prey while on deep dives). These findings come from analysis of data collected on animal-borne satellite tags affixed to individual whales subject to sonar exposure as part of experimental or observational studies. A second source of data about sonar response comes from bottom-mounted hydrophone arrays installed in several Navy testing ranges. These pick up echolocation clicks of nearby groups of deep-diving beaked whales, and this has been used to develop a sophisticated monitoring system that census the number and location of diving groups on the range and how this changes over time. The two data sources are different and complementary: the tag data represents information about individual response collected on small numbers (10s) of animals over relatively short time periods (10s of days), while the acoustic data represents indirect informationabout population responses (without being able to follow individuals) over multiple years.Here we propose to combine the two sources, enabling us to place the individual responses into a population context. For example, if the population data shows fewer echolocation dives during sonar, is this because individual animals leave the area or because they reduce the number of foraging dives? Many other similar questions can be resolved with a unified treatment. We will focus our work around the SOAR instrumented range in Southern California.We will develop a discrete-time spatially explicit movement model that can be fitted to data from multiple tagged individuals and also, by looking at the emergent spatial distribution of animals from the model, to the acoustic-derived population-level data. Initial tasks involve assembling the long-term acoustic dataset of beaked whale diving groups and sonar detections, andcollating this against tag data collected at the same time. We will undertake an exploratory analysis of linkages while developingthe unifying modeling approach. We will fit the models, and derive an enhanced description of behavioral response to sonar.The outputs can readily be incorporated into Navy acoustic effects analysis as well as models of population consequences of disturbance. The statistical models developed will be of use in many other situations, where individual- and population-level data are both available on the same population.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112613
Entities
People
- Len Thomas
Organizations
- Office of Naval Research
- United States Navy
- University of St Andrews