The DMON a circuit board and battery about the size of an iPhone sits inside the glider recording audio and generating spectrograms, a form of the audio that facilitates complex sound analysis. From the spectrogram, Baumgartner's software generates a "pitch track," a visual representation of a whale call, and estimates which species of whale made the call based on characteristics of the pitch track. Tallies of each species' detected calls and even a small subset of detected pitch tracks can be transmitted to shore by the vehicle. "Each pitch track takes less than 100 bytes, whereas transmitting just one of those calls as an audio clip would take about 8000 bytes of data," says Baumgartner. This makes the system efficient and economical. And, adds Baumgartner, it's also really flexible. It is easy to update the software to include a larger repertoire of whale calls into the software's "call library."
In addition to demonstrating the utility of the robots for the management and conservation of baleen whales, the project also has ongoing scientific objectives. One goal of the shipboard research team, in addition to spotting the whales, was to take measurements and collect biological samples of the tiny crustaceans or zooplankton upon which the whales feed, in an effort to characterize the oceanic conditions and to understand how those conditions impact the whale's food and ultimately attracts whales to the study area. "Untangling how that happens is a big deal," says Fratantoni.
"We wanted to figure out what right whales were feeding on in this area," says Baumgartner. "We took profiles of the temperature and the salinity of the water and sampled zooplankton throughout the water column to understand what might make this area attractive to right whales." Analysis of these data is in progress now.
Additional team members included representatives from the New England Aquarium who maintain a catalog of right whales and are experts in ident
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Woods Hole Oceanographic Institution