High-tech hitchhikers: computerized tag devices open new windows into whale behaviour and human impacts

Mark Johnson studied electronic engineering at the University of Auckland, New Zealand, finishing a Ph.D. in 1992. Since then, he has been at Woods Hole Oceanographic Institution in Massachusetts. Although initially hired to develop underwater data communications systems, he quickly gravitated to the marine mammal laboratory led by Peter Tyack. Since designing the DTAG in 1999, he has been involved in numerous field experiments and has been developing new analysis techniques for interpreting and visualizing tag data. His research interests are in sensors, signal processing, electronics, and animal behaviour, while hiking, climbing and conservation get him out of the office.

New computerized multi-sensor tags are leading a revolution in the study of whale behaviour. Combining high-resolution dive depth and orientation sensors, these devices can track every fluke stroke and breath of a whale for periods of hours to days. Add a concert-quality sound recording and you can capture the sounds made by the tagged whale and its neighbours as well as the background noise in its environment. One of the first of this new generation of sound-recording tags, the DTAG, has now been applied to over 300 marine mammals from 12 species as diverse as beaked whales, right whales and manatees. Among many other projects, researchers have used this paperback-sized device to measure coordination in foraging toothed whales, to calculate the drag and bouyancy of sperm whales, and to study the effect of human sounds on right whales. The suction cup attached tag also provided the first detailed view of echolocation in the wild when echoes from prey were recorded from enigmatic beaked whales hunting at depths of up to 2000 m. Given the density of data now collected by tags, just assimilating and visualizing the data can be a challenge. Methods developed in the fields of computer animation and virtual reality are being adapted to help researchers explore the whale's world. In this talk, we will review some of the scientific and conservation insights gained from the DTAG project and consider what future tags might tell us.