Sea Shepherd campaigners reported yesterday that the first dolphins of the season had been slaughtered in the small Japanese town of Taiji.

Activists from the environmentalist group have been monitoring the bay on which the town sits since the six-month dolphin hunting season began on September 1.

They are streaming live footage of the bay, into which local fishermen herd hundreds of dolphins for slaughter, a practice that thrust the small town into the global spotlight in 2010 when it became the subject of Oscar-winning documentary The Cove.

Defenders of the slaughter say that it is a tradition and point out that the species is not endangered, a position loudly echoed by the Japanese government.

But critics of the practice say there is insufficient demand for dolphin meat — which in any case contains dangerous levels of mercury.