Acoustic and Visual Monitoring for Marine Mammals at the Navy's Southern California Off-Shore Range
RC-1189
Objective
Southern California Bight bathymetry map shown with 200 m contours; the five stars depict the acoustic recording packages (ARPs) locations on Cortez and Tanner Banks
Environmental assessments are made to determine the potential impacts to marine mammals from Naval activities. The problem that the Navy confronts in preparing these assessments is a basic lack of scientific understanding of marine mammal population dynamics and behavioral ecology. To date, marine mammal assessment has relied on visual surveys from surface vessels and from the air. The difficulty and expense of these marine mammal visual surveys and the low numbers of sightings that they generate has impeded their usefulness for Navy environmental assessment. Acoustic techniques have the potential to provide an efficient and accurate method for assessing marine mammal populations in areas of naval interest such as within the Southern California Off-Shore Range (SCORE), a region where naval operations are frequently conducted and where marine mammals are seasonally abundant.
The objective of this project was to develop methods for acoustic monitoring of marine mammals. Researchers compared four methods for estimating marine mammal seasonality and relative abundance—aerial surveys (visual), ship-based transect surveys (visual), sonobuoy-based mobile acoustic surveys, and continuous fixed-site acoustic surveys. Simultaneous application of these techniques allowed for comparisons to determine the combination of methods most suitable for long-term marine mammal monitoring in the SCORE range.
Technical Approach
Aerial survey flights were conducted quarterly from 2001-2003 to assess whale abundance during each season. These surveys covered a series of lines ranging in length from 25 to 200 km, with a total survey area of approximately 12,600 km². Ship-based surveys consisting of both acoustic and visual techniques were conducted at SCORE six times each year. Ship-based visual surveys consisted of teams of observers working daylight hours to individually record sightings and group sizes. Biopsy, photo-identification, and detailed behavioral information were collected at select times during these surveys. Data from sonobuoys were used to estimate marine mammal calls, differentiate calls from individuals, and localize individual members. Fixed acoustic recording systems provided a continuous year-round survey for marine mammal presence. The project examined data from these systems and deployed seafloor broadband hydrophone recorders within the SCORE region where coverage was not available from existing hydrophones.
Benefits
For the Navy to comply with legislation protecting marine mammal habitat, data on marine mammal locations and seasonal densities within areas of frequent naval operations must be collected continuously. Acoustic methods were shown in this project to have great potential for improving marine mammal population assessments, as they produce significant numbers of detections and can be conducted with lower cost and less seasonal bias than visual methods. Such techniques are a first step in understanding the impact of sound on marine mammal behavior. SCORE personnel are now using these outcomes to operate a real-time system for marine mammal detection and classification, manage a database of seasonal marine mammal presence within SCORE, and run a predictive model for marine mammal presence under varying environmental conditions. (Project Completed - 2005)
Project Documents
Symposium & Workshop
FY 2013 New Start Project Selections
Points of Contact
Principal Investigator
Dr. John Hildebrand
Scripps Institution of Oceanography, UCSD
Phone: 858-534-4069
Fax: 858-534-6849
Program Manager
Resource Conservation and Climate Change
SERDP and ESTCP
Project Documents
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.