The primary objectives of the research program were as follows:
- Objective 1. Develop methods for estimating the density of cetacean species from fixed passive acoustic devices. Methods should be applicable to a wide range of scenarios, including dense and sparse arrays of permanent, bottom-mounted sensors and single bottom-mounted or floating sensors.
- Objective 2. Demonstrate the utility and generality of the methods by implementing them in a set of key test case studies. These test cases will also focus the methodological development to ensure its relevance to real-world applications. We aim as far as possible to leverage data that have already been collected, and acoustic detection, classification and localization methods that have already been developed.
- Objective 3. Promote adoption of the new methods in the marine mammal research community by (a) publishing results in the peer-reviewed literature, (b) archiving data and results in publicly available electronic storehouses (e.g., the Ocean Biogeographic Information System, OBIS), (c) holding a wrap-up workshop open to all interested researchers (participants will be self-funded; see Management Approach).
There are several optional objectives that might be pursued next:
- Option 1. Validate methods by comparing results from analyses of fixed acoustic data with those obtained by analysis of independent data collected using different modalities over the same time and space. For example, the acoustic data we use from PMRF were collected concurrently with aerial line transect survey data in the same region (Mobley 2005). In addition, shipboard line transect surveys are planned for the AUTEC range (Claridge, pers. comm.), potentially facilitating a validation study there.
- Option 2. Develop methods for scenarios not already addressed: (i) a vertically aligned set of hydrophones; (ii) a single cluster of bottom-mounted or floating sensors.
- Option 3. Obtain density estimates for species and areas of particular interest where fixed passive acoustic data already exist.
- Option 4. Investigate optimal survey protocols for the deployment of fixed passive acoustic devices for monitoring, and provide recommendations.
- Option 5. Make methods widely available to potential user community by incorporating into standard, widely used software.
We are not currently pursuing these options, but plan to propose additional research work along these lines if our primary objectives are met.