Mark Johnson, an engineer at Woods Hole Oceanographic Institution, is poised to attach a D-tag to a pilot whale off the island of El Hierro in the Canary Islands. Johnson, who developed the non-invasive tag to record whale movements and sounds in the deep, is co-author of a study (published online in May 2008) that used D-tags to reveal the distinctive way that pilots whales hunt.
Natacha Aguilar de Soto, lead author of the new (May 2008) report on pilot whale hunting behavior, coordinates whale-sighting and tagging efforts from a small boat off El Hierro, Canary Islands. She is a whale biologist at the University of La Laguna, Canary Islands. (Marta Guerra, University of La Laguna)
From an inflatable boat, Peter Madsen (University of Aarhus, Denmark), a co-author of the new study, keeps track of whale locations reported by spotters ashore. (Marta Guerra, University of La Laguna)
The work starts from above: Researcher Alejandro Padron from the University of La Laguna spends hours in blazing heat on the volcanic highlands of El Hierro, patiently locating whales for the whale-tagging scientists in boats. (Victor Gonzales Otaola, University of La Laguna)
In one clean lunge, WHOI engineer Mark Johnson applies a D-tag to the back of a fast-diving, short-finned pilot whale (Globicephala macrorynchus) that is resting on the surface. (Francisca Diáz, University of La Laguna)
Previous work on D-tagged Blainville’s beaked whales (Mesoplodon densirostris), such as this one, showed that their and pilot whales' feeding styles differ. Beaked whales make slow, long, deep foraging dives, while pilot whales make fast deep sprints. (Victor Gonzalez Otaola)
Mark Johnson holds a D-tag retrieved from the water. Suction cups on the tag keep it attached to the whale for several hours and then it pops off and floats to the surface, where a small antenna signals its position to researchers. (Courtesy of Mark Johnson, Woods Hole Oceanographic Institution)
In Johnson?s lab at WHOI, he and Aguilar de Soto spend hours analyzing the large files of numerical data collected by the tags on each whale?s dive, including depth and water temperature, the whale?s body orientation and tail strokes, the sounds emitted from and reflected back to the whale, and other sounds in the ocean. From these, they construct a picture of each dive. (Tom Kleindinst, Woods Hole Oceanographic Institution)