Using sensors of opportunity to estimate the density of blue and fin whales

The “Combining global OBS and CTBTO recordings to estimate abundance and density of fin and blue whales”, or CORTADO project, is using data from two bottom-sensor types to implement a suite of methods for estimating density of fin and blue whales. While previous studies have demonstrated the utility of Ocean Bottom Seismometers (OBS) and Comprehensive Test Ban Treaty Organization (CTBTO) hydroacoustic data, the techniques have not yet been developed to the point where they can be routinely applied by the wider research community. The primary CORTADO goal is to provide a set of software tools and training materials to expand access and usability of large, historic datasets. This talk will focus on using the CTBTO sensors for estimating density with a bearing method. This technique uses the bearing of and the signal-to-noise ratio for each detected call to estimate how many animals are producing a set of calls at any given time over the detection range of the sensor at all bearings. Applying this tool to several CTBTO sensors, we can compare the amount of blue and fin whales over time as well as spatially across the northern and southern coverage areas of the sensor array.