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A Tag Fit for a Porpoise

When Stacy DeRuiter came to the MIT/WHOI Joint Program in 2003, the newly developed “D-tag” — a non-invasive, temporary digital recording device designed for use on whales — was sparking a revolution in marine mammal research. Working in the Marine Mammal Behavior Laboratory at WHOI, DeRuiter wanted to use such a device to study some of the smallest cetaceans, harbor porpoises. She teamed with fellow graduate student Alexander Bahr, an electrical engineer, to create a smaller version of the tag tuned to capture the higher frequency sounds made by porpoises. DeRuiter tested the tag on captive harbor porpoises in the Fjord & Baelt Center in Kerteminde, Denmark, and gathered audio data on how they used sound to forage for fish, including recording behaviors scientists had not seen before in animals that use sonar.
(Photo by Alexander Bahr, Woods Hole Oceanographic Institution)