Earlier this year, a documentary film called The Cove rocked the world with its graphic exposé of the annual killing of more than 2,500 dolphins in a National Park at Taiji, Wakayama in Japan. Secretly filmed in 2007 using underwater microphones and high-definition cameras disguised as rocks, The Cove provided an unprecedented, shocking look into a tradition that even Japanese people didn’t know about.

Happily, the film -- or at least, the work of activists worldwide -- has apparently made a difference already. Sept. 1 was set to begin the annual tradition of killing dolphins en masse in Taiji, but when activists arrived on the scene, there were no dolphin killers in sight.

Richard O’Barry of the Save Japan Dolphins Coalition reports that when he descended upon the notorious cove featured in the film accompanied by media representatives from around the world, he was met not by fishermen engaged in a bloody massacre but by nine Japanese policemen.

“And as I was talking with the police, as the international journalists stood around listening, suddenly a camera crew arrived from Japan! And then another! And then still another!,” O’Barry wrote at TakePart.

“You have to understand that this is so important. These TV stations have refused to cover the story in Taiji for years and years. Now, for the first time, they have shown up, with cameras rolling. The head policeman talking with me even said, for the cameras, that the police are not there to support the dolphin-killing fishermen. We shook hands, and they left.”

O’Barry, who was featured in The Cove, hopes that the international attention that the film received will spur Taiji to rescue its reputation by putting a stop to the practice.

“And because of The Cove movie, the dolphin killers must now fear hidden cameras and microphones, even when they think we are not here.”

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The story so far: Taiji's sister city in Australia severs ties over the controversy