Fidori is trying to squeeze the air pockets from her ill-fitting wetsuit. She's milling around with 10 other Japanese women, silent and apprehensive as they wait to fulfil their lifetime ambition. Before them is a pool of dolphins. "I've got pictures of them all over my walls," says Fidori. "I just want to touch them." Now isn't the moment to tell her that just a few days earlier, I ate one. Not a whole one, but large, crimson slabs of dolphin meat, washed down with a glass of sake.
Pressure from the animal rights community meant that the last British dolphinarium closed in 1993. In Japan, however, they've never been more popular. There are now more than 50 across the country, and in Yokohama, where Fidori is being dragged through the water by a bottlenose, the marine park has taken over an entire island. But there's a reluctance to talk about how the dolphins got from the sea to the pool. When pressed, one of the trainerssays "from Taiji". When asked to elaborate, a press officer intervenes.
The secret of Japan's dolphin supply is only now starting to leak out to the rest of the world. The marine parks are worried that, if the details become known, international pressure on the Japanese government might put an end to the business.
Taiji is a small fishing town on the south-east coast of Japan. It's the country's main supplier of performing dolphins. And just down the road from two dolphinariums, the dolphin hunters are preparing their boats. This is "drive-hunt" season. The hunters take to the water armed with metal poles. When they find a pod of dolphins they surround it and bang the poles in the water. The clattering noise confuses the dolphins' sonar, and they thrash around in confusion as the hunters drive them towards the shore. Unlike harpooning, this method can pull in a hundred or so dolphins at a time. But death is slow. The animals are knifed and slashed until the water runs red. Still conscious, they are then hoisted on to trucks.
But not all the men dragging dolphins from the water are fishermen. Some are from marine parks, here to choose their latest performers. They get first pick, while those not chosen are butchered for food. Although many of us have idealistic notions that marine parks in some way protect sea life, in Taiji they are in direct alliance with the fishermen who kill it. It's a strange interdependence that the aquariums would rather we didn't know about. But worse than that, animal rights activists argue that drive-hunts not only serve the dolphinariums but are actually dependent on the money coming in from the sale of live animals. In other words, they say it's the marine parks that are behind the world's biggest slaughter of dolphins.
The main proponent of this view is American activist Ric O'Barry, from the conservation group One Voice. He flies from his home in Miami each year to spend six months protesting in Taiji. "It's the captivity industry that is driving [the killing] today," he says. "The dolphinariums are paying more for the high-value dolphins. That money is what keeps this thing going."
O'Barry says a live dolphin can sell for $30,000 (£16,200), while those caught for meat fetch as little as $300 (£160). Last year the dolphin hunters of Taiji sold 78 animals to marine parks, a trade that would appear to have netted them far more than they could hope to make from the meat. If true, it would mean that the marine parks fuel the drive-hunts - and every dolphin-lover visiting a marine park in Japan is inadvertently propping up the trade for meat, too.
Those allowed to catch dolphins are a small, privileged elite - membership of which is usually passed from father to son. The diminutive figure of Akira Takeuchi, the leader of the dolphin hunters, isn't the barbaric animal rights abuser one might expect. He's a quiet dignified man, overwhelmed by the recent appearance of protesters. He, like the others, doesn't see dolphins as mammals. To him they're just "big fish" to be caught and turned into sashimi. "How would people in the UK like it if a group of Japanese turned up to picket a fox hunt?" he says. The dolphin hunters are dismissive about their relationship with the marine parks. "The main reason for the hunt," they say, "is for food, not to supply the aquariums." The prices we've been quoted they dismiss in gales of laughter.
Almost every dolphinarium in Japan is reliant on the annual blood bath at Taiji and that of another town a little further up the coast, Futo. Here some dolphins are dragged, still alive, behind trucks, their skin ripping off on the tarmac. At the slaughterhouse, the men from the dolphinariums pick out the lucky ones who will live.
The manager of the oldest dolphinarium in Taiji, who would not give his name, takes me to see his prize assets. Leaping and spinning in their tiny pool, he admits these dolphins were dragged from the sea in a drive-hunt. He also admits he eats them. From a Western perspective, it's a seemingly grotesque confusion of roles: dolphin-keeper and dolphin-eater. I'm puzzled. He's puzzled that I'm puzzled. "Hunting dolphins is different from killing other animals," he says. "It's completely different because we have been doing this since we were born. We don't feel cruel to the dolphins or feel sick." He's thoughtful and articulate, but we're not making much progress. The cultural divide is too great. We leave him smiling in his marine park's reception area, where visitors can buy fluffy toy dolphins or the real thing - in steaks.
But, it's not only Japanese marine parks that source from the drive-hunts. Tim Desmond, an American who's a regular shopper in Taiji, chooses the best and then flies them to his marine park in the Philippines - Ocean Adventure - which is one of the most popular attractions in the country. Desmond is reluctant to talk, saying the animal rights activists have made him a pantomime villain. It turns out that he and O'Barry are old adversaries.
Desmond has the air of an excited academic, all hand gestures and impressive-sounding theories on the ethics of keeping animals in captivity. Outside, his Taiji dolphins rip through the water as the children whoop and pop music blares from speakers. But here's the surprise: Desmond claims he's the conservationist, not the demonstrators trying to stop the drive-hunts. He says he's saving the dolphins from the hunters' knives. "Every animal had a life expectancy of less than one day when we acquired them," he says. "These animals were either going to be taken alive or die." He argues that Taiji is the most environmentally friendly place to acquire dolphins. If he ordered them from elsewhere - Cuba for instance, which is a major supplier - the dolphins would be caught specifically for him: in other words, he would be guilty of interfering with the species. The drive-hunts, on the other hand, are a pre-existing situation. His dolphins, he says, are a bi-product of the catch.
But O'Barry says: "If Desmond was a conservationist, he would be there with a sign saying, 'Stop the killing'."
Back in Yokohama, a delighted Fidori towels herself down. I delicately suggest she might want to know the origin of the dolphins. She watches our pictures speechless; in tears. She, like everyone else we met outside the dolphin-hunting towns, was unaware of the drives, or that dolphins were eaten. It appears the Japanese media prefers not to mention it. As O'Barry says, public opinion here doesn't need changing, it just needs informing.
Paul Kenyon's 'Undercover World: the Dolphin Hunters' is on BBC2 tonight at 7.30pmReuse content