The killing of dolphins is not banned by international law, but the Sea Shepherd Conservation Society, which seeks to ban the practice, denounced the method used in the western Japanese town of Taiji.
"It's a wholesale slaughter, which results in immense suffering for these animals," said Nik Hensey, an activist with the California-based group. "It's a sight that one just can't imagine."
Town officials declined comment, but an official with the local fishermen's union, speaking on condition of anonymity, said the hunts are conducted as humanely as possible, and noted that dolphin hunts have been part of local culture for 400 years.
In the videotape, fishermen pound on the water, causing waves that confuse the animals' sense of direction, then corral the dolphins into small coves, where they can be easily killed.
Sea Shepherd made the videotape and provided a copy to Associated Press Television News.
Shuichi Sato, an official at the whaling section of Japan's Fisheries Agency, said there is another village in Japan where the local fishermen catch dolphins in the same manner as in Taiji, while others use harpoons farther from shore. He said the hunting of dolphins is no worse than the slaughter of cows, sheep or other animals consumed by humans.
"What's wrong with eating dolphins? There are Hindus, Muslims around the world who don't eat beef or pork, but do they tell Europeans not to eat this meat," Sato said. "To impose one's culture on others is to deny the culture of other countries."
Though subject to government-set quotas, the hunts are not banned under Japanese law and are not subject to international regulations because they are done near the shore.
Fishermen in Taiji hunt dolphins from October to April. They've caught more than 60 striped dolphins so far this year under the government quota system. The meat is usually canned and sold in supermarkets.