A group of mostly Australian and American activists, some on surfboards, left flowers at sea off Taiji, a historic whaling town some 450 km (280 miles) west of Tokyo.
But the ceremony on Monday, shown in a video provided by the activists, was interrupted by a boat of local fishermen, who used a long pole to chase away the protesters. Whales could be seen swimming on the other side of the boat.
"It's innocence being slaughtered, it's innocence being taken away," said Hayden Panettiere, an actress in the U.S. TV series "Heroes," who took part in the protest.
"Dolphins and whales are probably one of the friendliest animals on the face of this planet."
On land, one of the fisherman shouted at a foreign television crew covering the protest. "Go home, you're in the way," he said.
Japan abandoned commercial whaling in accordance with an international moratorium in 1986, but conducts what it calls "scientific research" whaling every year and is pushing for the resumption of commercial whaling.
Critics say most of the whale meat ends up in Japanese supermarkets and restaurants and that Japan rarely publishes its scientific findings.
Protesters say there is no point to whaling, citing research by Taiji assemblymen this year which showed local whale meat contained levels of mercury 10 to 16 times more than advised by the Health Ministry.
"The justification is for the meat, but we now know that the meat is highly contaminated," said Ric O'Barry, an activist who trained dolphins for the U.S. TV series "Flipper" in the 1960s.
Around 2,000 whales are known to be killed in Taiji every year during the whaling season from September to March. Some 14,000 whales were caught by Japanese ships in total last year, according to Japan's Fisheries Agency.
A Fisheries Agency official said he saw no need to stop consumers from eating whale and dolphin meat. "Because whales and dolphins are at the top of the food chain in the ecological system, they tend to have higher mercury levels compared to other species," said Hideki Moronuki, a Japanese Fisheries Agency official in Tokyo.
He added that the Health Ministry has been advising pregnant woman not to eat the meat too often. "But trying to stop people from eating the meat altogether for that reason seems irrational to me," he added.
Japan argues its whaling program helps the understanding of whale stocks and species and also considers whaling a cherished cultural tradition, although studies show the public's appetite for the delicacy is declining.
© 2007 Reuters