In an unusual move, U.S. ambassador to Japan Caroline Kennedy has expressed deep concern over the traditional dolphin hunt in western Japan, where local fisherman corral the mammals into a secluded bay before killing many for meat.
The annual hunt currently under way in Taiji in western Japan has long been a source of controversy and was the topic of "The Cove", an Oscar-winning documentary.
"(I am) deeply concerned by inhumanness of drive hunt dolphin killing," Kennedy tweeted at the weekend, adding that the U.S. government opposes drive hunt fishing.
Every year the fishermen of Taiji, in Wakayama prefecture, drive hundreds of dolphins into a cove, select some for sale to marine parks, release some back into the sea and kill the rest for meat.
Japan has long maintained that killing dolphins is not banned under any international treaty and that the animals are not endangered.
"Dolphin fishing is one of Japan's traditional fishing techniques and is carried out appropriately in accordance with the law," Chief Cabinet Secretary Yoshihide Suga told reporters at a regular news conference in Tokyo on Monday.
"We will explain our stance to the American side," said Suga, adding marine mammals were an important marine resource and should be fished in a sustainable way.
Sea Shepherd, one of the animal protection groups that monitor fishermen in Taiji, said more than 200 dolphins had been rounded up into the secluded bay.
"It takes up to 20 to 30 minutes for these dolphins to die, where they bleed out, suffocate or drown in the process of being dragged to the butcher house," Sea Shepherd activist Melissa Sehgal told Reuters.
Sehgal added that the bottlenose dolphins were also valuable as they can be trained to do tricks. The Taiji fishing union was not immediately available for comment.
Taiji came into the spotlight after the 2009 release of "The Cove", directed by former National Geographic photographer Louie Psihoyos. It shows the hunt in grisly detail and calls for an end to commercial fishing of marine mammals.
Fishermen say the cull is a traditional part of their livelihood in an area that has fished dolphins and whales for thousands of years.
The dolphin hunting season runs yearly from September to March, the Taiji fishing association said. Sea Shepherd says 176 marine mammals had been killed this season, including bottlenose, spotted, striped and risso's dolphins.
Exact monitoring is difficult, with fishermen erecting tarpaulins over their killing area and blocking access to the cove.