Louie Psihoyos riding to Oscar glory with The Cove

The first-time documentary maker talks about his harrowing dolphin film that has been nominated for an Academy Award.

Louie Psihoyos, left, and the production manager, Joe Chisholm, and the associate producer Charles Hambleton filming The Cove.

Louie Psihoyos had never made a film before, so he thought himself pretty lucky to be offered free advice for his maiden project by Steven Spielberg. "We were down in the Caribbean and my son wanted to sleep over with a kid he had met from the boat next door, which turned out to be the Spielbergs vacationing on the Gettys' yacht," Psihoyos says. "So naturally the kid's father, Steven Spielberg, wants to meet the family of this kid who is going to be sleeping over and he asked me what I do for a living. So I told him I was making a movie and I had never done it before. The first thing he said was 'never work with animals or boats'." Psihoyos's angular features explode with a manic chuckle.

The Cove, Psihoyos's first feature-length documentary, is a gripping exposé of an annual mass dolphin slaughter off the coast of Japan and it involves lots of animals and lots of boats. "So I guess I completely ignored him." Psihoyos continues between snorts of self-deprecation. "Smart move." But ignoring Spielberg has done Psihoyos no harm as the film has been shortlisted for an Oscar in the much coveted Best Documentary category.

At screenings across the world since it opened last year, audiences have cheered, laughed and wept in almost equal measure as the gripping and often gruesome tale unfolds with furious pace and Hitchcockian intensity. "The reception we are getting all over the world is just remarkable," Psihoyos says, perched on a large rock beside a brook that runs through the expansive back yard of his Colorado home.

"We knew the movie was good, but we did not know so many people would agree with us," he adds with a shrug of disbelief. Psihoyos and a small band of photographers, covert surveillance experts and Hollywood prop men, who spent close to three years producing The Cove, have been described as Ocean's Eleven meets Greenpeace. The celebrated US film critic Roger Ebert has already proclaimed The Cove a dead cert to win the Oscar, while Psihoyos is being described as the next Michael Moore.

The film has already won awards at festivals around the world. The Cove aims to expose the Japanese practice that every year, from September 1 to the end of April, sees a small band of fishermen from the coastal town of Taiji head out to sea in a dozen or so small boats looking for great shoals of migrating dolphins. When they find their quarry, they confuse the speeding cetaceans by banging long metal poles on their hulls, sending a cacophony of confusing sound waves to the depths.

The fishermen use the sonar assault to herd the dolphins back to Taiji, where they are corralled in a hidden cove. Once trapped behind fishing nets that block their exit to the sea, the dolphins are left packed like sardines and at the mercy of the fishermen. A few are sold for as much as $150,000 (Dh551,000) each to aquariums and dolphin shows in America and elsewhere, while the rest are butchered and their meat sold, often on the black market labelled as whale flesh.

By the end of every season between 17,000 and 23,000 dolphins have been slaughtered in Japan, the largest concentration in Taiji. "The Taiji dolphins had been filmed before but never like this," Psihoyos says. "It was an incredibly difficult film to shoot under incredibly difficult circumstances." The idea to shoot The Cove came to Psihoyos when he visited an annual conference for marine biologists in California. The keynote speaker at the event was supposed to be Ric O'Barry, the dolphin-trainer-turned-activist who made his name in the 1960s as the man behind Flipper, the American television series about a helpful dolphin. But O'Barry was pulled from the bill at the last minute, apparently at the behest of SeaWorld, the US aquarium operator and a sponsor of the event.

Psihoyos called O'Barry in Miami and asked him why he had been banned from speaking. "He said, 'I was going to talk about this dolphin slaughter in Taiji, and they don't want me to talk about it because of my message about captivity,'" Psihoyos recalls. The problems of keeping marine animals in captivity have been in the news recently after the SeaWorld trainer Dawn Brancheau was dragged to her death by a killer whale during a performance last month.

Psihoyos recalls: "At this point I didn't even know that there was an issue about dolphin captivity. I didn't know about dolphin slaughters." O'Barry soon enlightened him, and when Psihoyos asked if there was any organisation doing anything to expose the slaughter in Taiji he replied: "Me. And I am going next week, you want to come?" Psihoyos says it happened as fast as that. "But I had at this point no idea how to make a film so I took a three-day crash course and caught up with Ric in Japan," he adds.

When Spielberg warned Psihoyos never to work with animals or boats he could have added razor wire, attack dogs, angry fishermen and obstructive local officials to the list. Psihoyos encountered all of them. "We did everything wrong as first-time filmmakers," he says. "But I think it was really that naivety that allowed us to tell the story in the way that we did. We weren't just thinking outside the box, we didn't know there was a box."

Simon Hutchins, a key member of the commando film crew that made The Cove, created several -innovative cameras without which The Cove could not have been filmed. One was mounted on a -remote-control helicopter to film the slaughter from the sky, another was hidden inside an enormous helium balloon in the shape of a whale that foxed local authorities trying to close the production down. More of Hutchins's cameras were hidden inside fake rocks built especially for the expedition by special-effects model makers at George Lucas's Industrial Light and Magic.

"Everything we had to do was in the middle of the night with cops on our tail, basically launching a covert mission into unfriendly territory every night," says Psihoyos. The Cove begins with O'Barry driving through the eerily quiet streets of Taiji, which are adorned at every turn with large statues of happy, smiling dolphins and whales. He wears a black wig given to him by Viki Psihoyos, Louie's wife, a surgical mask and big sunglasses. O'Barry has been arrested and thrown out of Taiji more times than he can remember.

Psihoyos says: "It was like walking into a Stephen King novel. You cross the bridge into Taiji, and there are two statues of bottlenose dolphins. Then you see a statue of a humpback whale and her calf. Then there is this anime wall with 'We love dolphins' in English. Then there is all this tiling with every known species of dolphin, whale and porpoise embedded in the street. A whale tail sculpture fountain, then the whaling ship and the whaling museum, whaling shops. It's creepy."

And then, between the whaling museum and Taiji city hall is the Wakami Prefecture Nature Preserve, a national park along what Psihoyos describes as the most beautiful coastline he has ever seen. The cove where the dolphins are slaughtered by 26 fishermen is part of the park, which is supposed to be both a national treasure for Japanese people to enjoy and a refuge point during a tsunami. However, it is closed off to all except the dolphin hunters. The mayor claims there is a danger of falling rocks, but this does not seem to bother the fishermen.

"My mouth was wide open," Psihoyos says. "The largest slaughter of dolphins on the planet happening right here where there is supposed to be a marine sanctuary, and it is going on under the nose of the Japanese people and they don't even know it." Psihoyos's real genius in making The Cove is the way in which he went about capturing evidence of the slaughter, and the way he translates the complex mission on to the screen.

Almost all of the action is filmed at night, with heat sensing cameras and night-vision equipment more commonly used by the US military. He even used the world champion free divers Mandy-Rae Cruickshank and Kirk Krack to place underwater sound-recording equipment on the seabed at night. But it is a few minutes of perfect footage captured by one of the -hidden cameras that are the film's greatest achievement.

A perfectly framed shot of the dolphin fishermen standing around a campfire in the minutes before sunrise, discussing their bloody trade and the difficulties of whaling and dolphin hunting all over the world thanks to the likes of Greenpeace and the Sea Shepherds, is both shocking and mesmerisingly beautiful to watch. What's more, Psihoyos nearly failed to capture the killer scene because of a technical hitch that left him dangling from a cliff face by a rope for several hours after he had placed one of the rock cameras high above the deadly cove.

"I had started to rappel down the cliff when I heard screaming in the woods below me," Psihoyos recalls. "Unbeknown to us, another activist was hiding out up there, an Englishwoman, and she had been caught by the fishermen. I couldn't get out, I had to wait until it was safe for my team to extract me. Needless to say, the footage from my camera was unusable that night, so I was pretty depressed." But that changed back at the hotel when Psihoyos reviewed the footage shot by the assistant director, Charles Hambleton.

"I realised that Charles had placed a camera right up against the fishermen's campfire. The frame was perfectly composed. I worked at National Geographic over a period of 18 years as a photographer and if I had been there myself I could not have placed it better," Psihoyos says. But he knew that regardless of the technical and cinematic achievements of his film, he would need something more to convince the Japanese people that what was happening at the cove must stop.

After all, there have been protests for decades against Japanese whale-hunting and the country's predilection for whale and dolphin meat. Criticism of the trade in dolphins and whales is often viewed by the Japanese as an attack on centuries-old traditions. "I had no real interest in filming just the slaughter," says Psihoyos. "The idea for me originally was to show the discrepancy between western and eastern thought. In our culture, we revere the dolphin as this almost mythical creature, and here they kill them to eat them."

But it was in researching this last element that Psihoyos and his team made a discovery that changed the direction of the film. Dolphin meat, along with the meat of many other apex predators in the oceans, contains levels of mercury far higher than the human body can tolerate. What was worse, the fishermen and politicians of Taiji were giving away meat from the slaughter to local schools, to be served as free school lunch; a PR exercise to show the benefits of mass dolphin slaughter.

The revelation was also a cause for concern for Psihoyos himself. "I had not eaten meat since 1986, when I went to a slaughterhouse, so I basically lived on fish," Psihoyos says. "But while I was in Japan working with a group of doctors on the dolphin meat, I took them all out for lunch, for sushi, but I noticed none of them were eating from the giant platters we bought for them. "I said, What is this? You are Japanese, why are you not eating the sushi? And they told me they had not eaten any fish since they started testing large predator fish for mercury poisoning, and they suggested I get myself checked out."

Psihoyos had the highest levels of mercury his doctor had ever seen. "I thought I was eating healthily. But I had to stop eating large fish. I cut fish out of my diet completely for a time. I was at 40 parts per million of mercury in my blood. Over a period of time I was able to get it down to three. By the way, one part per million is high and 0.4 parts per million is the level the Japanese government allows in seafood."

The Taiji dolphins have been found with mercury levels registering between five and 5,000 times the Japanese government's prescribed limit. Psihoyos is flattered by the accolades from US critics, but keeps it in proportion. "If people are saying I'm the next Michael Moore then that's great, but we have not tried to do what he does. Michael has a very particular style and he does it very well." Psihoyos says he is far more influenced in his work by his friend and fellow Colorado native Hunter S Thompson. The pair became friends many years ago, but it was not until the godfather of gonzo journalism died that Psihoyos realised the true value of their friendship.

"We were at Hunter's memorial service and Bill Murray got up to speak," Psihoyos recalls. "Far from recounting tales of great excess and debauchery, he told us of how his fondest memories of spending time with Hunter were nights in his kitchen reading passages of great literature to one another. And I agreed with that. Hunter was a great literary figure, yet people remember him for his wild side."

Psihoyos believes film, particularly documentary, should aspire to be the great literature of the modern age. Another principle he brings to his films - his next one, about the food chain and extinction, is already in the works - is something called gaiatsu, a Japanese term meaning external pressure. "The Cove is an exercise in gaiatsu," Psihoyos says. "Gaiatsu is responsible for the majority of social and political changes in Japan since the end of the Second World War and it is our belief that through gaiatsu we can bring about the end of the dolphin slaughter, not just in Taiji, but all over Japan."