Hunt causes worldwide ripple effect
Some dolphins are caught and sold to theme parks, but most are killed for food. Some are killed for 'pest control', or culled, because there are too many dolphins eating fishermen's catch and affecting their livelihood.
In 2009, a documentary film was released about the secret slaughter of dolphins in a small Japanese town called Taiji. Directed by Louie Psihoyos, The Cove follows dolphin activists as they venture into the town to try to expose the practice - all while local fishermen try to block filming.
The film's graphic footage and gripping storytelling quickly turned the spotlight on dolphin-hunting.
Critics of The Cove say the film is emotionally manipulative and exaggerates the killing of dolphins.
Why did the movie become so controversial? Is dolphin-hunting as bad as the movie makes it look?
How dolphins are killed
Activists against dolphin-hunting say Taiji fishermen kill the mammals in an inhumane way. The local residents call it oikomi, or dolphin drive hunting. It involves fishermen rounding up dolphins into a hidden cove: they use devices to create a wall of sound to direct the animals.
Once the dolphins are in the narrow cove, a net prevents them from swimming away. Feeling trapped, many panic and become stressed, activists say.
The next day, fishermen stab all the dolphins to death with spears, leaving the sea blood-red.
The Cove highlights the killings in a powerful way. Filmmakers had to capture the slaughter with hidden cameras because they were not allowed access to the cove.
But Taiji mayor Kazutaka Sangen said the area was cordoned off simply because they did not want the public to see the killings.
'It is unpleasant to look at, as is true of killing cows or pigs or any other animal,' he said.
Taiji official Miyato Sugimori said the dolphin conflict is nothing more than a cultural clash.
He likened dolphin meat, eaten by Taiji residents, to beef eaten by Westerners, or kangaroo meat eaten by Australians.
Local councillor Hisato Ryono said whaling and dolphin-hunting in the town were part of a long tradition dating back to the 1600s.
He objects to the movie on several fronts.
The Cove calls Taiji a 'small town with a big secret', but Ryono says it has always been known as the 'whale town'. He thinks the movie is exaggerating the whole issue.
There are other arguments that support Taiji's tradition.
First, dolphins are not endangered - a fact activist Ric O'Barry has acknowledged.
Second, the number of dolphins killed in Taiji is far fewer than in other parts of Japan and the rest of the world.
Japan sets a yearly hunting limit of 23,000 dolphins - and only about 2,000 dolphins are killed in Taiji.
Also, dolphin-hunting is not an illegal activity. Taiji's mayor urged the West to respect a nation's culture.
Taiji is a small town with a population of about 3,000 people.
Sangen said the town relied on whaling and dolphin-hunting because it did not have enough fresh water for any agricultural activities.
The mammals are the only sources of income for Taiji.
A live bottlenose dolphin can sell for up to US$150,000, according to SaveJapanDolphin.org. The meat from one dolphin can be sold for as much as US$600.
Dangerous as food
Most dolphins are killed for food, but some say dolphin meat contains too much mercury. As a result, activists argue, there is no reason dolphins should be hunted.
Mercury accumulates in a dolphin's body and cannot be expelled. For example, when a big fish eats a small fish, it also gobbles up the mercury in the small fish. The level of mercury keeps multiplying as it goes up the food chain. Dolphins are high on the food chain, so their mercury levels are high.
Mercury can poison humans if eaten in large amounts. It affects our brain and nervous system, and can cause memory and vision loss, among other health problems.
Some regions in Japan traditionally eat dolphin meat. In Taiji, the level of mercury found in human hair samples was 10 times higher than the national average, researchers found.
But critics of that 2010 research pointed out that none of the Taiji residents who took part in the study had suffered from mercury-related diseases.
Dolphin lover Ric O'Barry has one big regret in his life: he used to be a dolphin trainer for the popular American television show Flipper. But now he works to save dolphins from being captured for such entertainment.
O'Barry told his story earlier this month when he visited several schools and universities in Hong Kong. He emphasised the importance of dolphin preservation.
After the success of Flipper in the 1970s, many dolphin parks popped up around the world, a fact that upsets O'Barry.
His life changed after one of his dolphins killed itself by deciding to stop breathing.
'I was motivated by guilt, because it was the Flipper TV show that created a lot of these parks,' he said during a visit to Renaissance College in Ma On Shan.
O'Barry attracted international attention when he appeared in The Cove, a documentary about dolphin-hunting. It won an Oscar in 2010. The film follows O'Barry and a team of activists as they attempt to save dolphins near the coastal town of Taiji, in Japan. The documentary sparked much controversy.
O'Barry's activism is no longer motivated by guilt. He said guilt and grief were negative emotions, and he had let them go. 'I am motivated by results,' he said. 'I actually see results, and that's what keeps me going.'
According to conservationists, fewer dolphins were killed this year (786) compared to last season's 1,190. This year's hunting season also ended four weeks early.
O'Barry has written several books about saving dolphins. He also founded Ric O'Barry's Dolphin Project and is the director of Save Japan Dolphins, a campaign to end dolphin-hunting in Japan.
In Hong Kong, Save Japan Dolphins has a local chapter which was started by students at Renaissance College last year. So far, the students have raised funds by selling T-shirts and wristbands. They use social media such as Facebook and YouTube to raise local awareness about the issue. Last month, four students from Sha Tin College organised a week-long campaign, raising HK$10,000 for Save Japan Dolphins.
Ocean Park once sourced dolphins from Taiji, but it said no dolphins had been imported from there since 1981.
Voices: What people are saying
'Everyone around here knows about it. The water nearby turns red during the hunt. The actual killing is done in a concealed area because it is unpleasant to look at, as is true of killing cows or pigs or any other animal.'
Hisato Ryono, Taiji councillor
'I feel that they should have declined the award.'
Tetsuya Endo, an associate professor at Health Sciences University of Hokkaido, about The Cove filmmakers receiving an Academy Award
'I like dolphins, and I don't see why they would slaughter them. I can't compare dolphins and cows. They're not on the same level of mental capacity.'
Alex Sarkissian, 17, a student from Canada
'This is not North Korea. It's not China, and it's not Cuba. It's a democratic society. There's a very small minority of radicals who are going to theatre owners and threatening them. They don't want people to see this film.'
Ric O'Barry, activist, urging Japanese theatres to screen The Cove