This type of tag, however, requires a buoy to carry the aerial, and this is attached to the shark by a ten-metre-long line. (The line is needed because the sharks themselves rarely break the surface, and the transmitter cannot signal to the satellite from under water.) Two American biologists, Scott Eckert and Brent Stewart, from the Hubbs-Sea World Research Institute in San Diego, have had some success with satellite tracking.

ECONOMIST: Whale sharks