Focused Next Steps for Behavioral and Physiological Response Studies with Social Delphinids Off Southern California
Abstract
Delphinid cetaceans are among the most common marine mammals in many coastal areas, comprising a disproportionately large percentage of animals predicted to be affected by human disturbances including Navy active sonar. To date these predictions have been based on very limited indirect and/or contextually inappropriate data. Much has been learned using animal-borne tags to monitor behavior and behavioral response in some species. However, such approaches are either challenging or inappropriate to apply to small, fast delphinids that occur in large groups and whose social response is strongly mediated by group dynamics. Through a recent pilot and implementation effort, we have developed, adapted, and applied a novel integration of methods to measure baseline behavior and behavioraland physiological responses to noise in small delphinid cetaceans (Durban et al., 2022). This approach relies on an integration of fine-scale measurements of spacing, speed, and directionality using photogrammetry from unmanned aerial systems (UAS), broad-scale visual monitoring of group movement and behavior using theodolites and powerful binoculars, strategic deployments of drifting passiveacoustic recorders, and strategic biopsy tissue samples. These methods have been applied within controlled exposure experiments (CEEs) using no-noise controls and known noise exposure conditions using an experimental sound source to generate a robust sample size (~n=15) of CEEs for each of two different common dolphin species. We propose to: (1) expand sample sizes for a third delphinid species (bottlenose dolphins) to generate a comparably robust and publishable sample size focused primarily on simulated (experimental) MFAS sources for comparison with operational (helicopter dipping) Navy sonars; and (2) substantially expand and enhance analytical methods for quantifying and tracking movement and social behavior for all focal dolphin species. Results will be published, presented at scientific meetings as well as ONR review meetings, and directly integrated into Navy assessments of baseline and sonar response data in regulatory compliance processes.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 29, 2023
- Source ID
- N000142312497
Entities
People
- Brandon L. Southall
Organizations
- Office of Naval Research
- Southall Environmental Associates (United States)
- United States Navy