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

Young scrum-half Dave Lewis, playing just his second Premiership game, made the initial break after a well worked line-out and although his attempted long pass to Iain Balshaw drifted forward, the referee let play continue.

BBC: Gloucester 39-10 Bristol

However, he was still smarting from an overrule when facing break point in the second set, when the line judge mistakenly called a Federer shot long and the Swiss lost the replayed point.

BBC: Andy Murray retains belief he can win Grand Slam title