Paul Watson has been engaging in acts of derring-do on behalf of the animal kingdom for more than 30 years.

In the early 1970s, not long after he co-founded the Greenpeace environmental movement, the Canadian was among a small group of activists who took to the seas off California to try to stop a Soviet fleet from killing whales.

Watson - Greenpeace membership number: 007 - was steering a small, fast, inflatable Zodiac speedboat. His aim was to position himself between the whales and the Soviet harpoons. The whalers had already opened fire on a passing pod of whales, and at one point an injured sperm whale broke away from the group. It headed straight for Watson’s boat.

As Watson heaved on his rudder, the whale passed a few feet away, its eye clear of the water. It seemed to be staring directly at the men who were trying to save it. Watson has never forgotten that moment.

“In an instant my life was transformed and a purpose for my life was reverently established,” said the man who would later fall out with Greenpeace and found one of the world’s most aggressive environmental groups, the US-based Sea Shepherd Conservation Society.

Watson recently wrote a 1,600-line poem about his efforts to protect that whale. It began: “Leviathan’s solitary eye haunts me still/ I am obsessed and driven mad with anger.”

Watson’s obsession and anger burn as fiercely as ever.

In the heaving waters of the Southern Ocean last week, it was the black-hulled Sea Shepherd flagship, the Steve Irwin - a former Scottish fisheries vessel renamed after the Australian wildlife expert killed by a stingray 16 months ago - that was embroiled in a hair-raising skirmish with a Japanese whaling fleet less than 200 miles off the coast of Antarctica.

At 57, Watson is too old – and a little too heavy – to be hopping in and out of Zodiac speedboats. But he was there on the bridge as two of his crew members set off an international furore by launching a mid-ocean boarding raid on the Yushin Maru No 2, part of a Japanese whaling fleet.

The two men, one a Briton, were seized by the Japanese and restrained on deck with rope and cable ties – in full view of the cameras. Watson could barely restrain his glee. His antics were being reported by almost every media outlet in the world. The plight of the whale was back in the news.

Watson could seemingly chalk up yet another triumph for his explosive strategy of calculated outrage, reckless confrontation and scathing insult. While the “wusses” of Greenpeace are mincing around like “the Avon ladies of the environment”, he says, Sea Shepherd is in the thick of the fight to save the whale.

“The Japanese haven’t killed a whale in a week,” boasted Watson, who says he has not seen one die since 1977. “We have been successful, and we’re going to try to get them not to kill a whale for another week, and maybe another week after that.”

Yet for much of the environmental world, Watson is more of a scoundrel than a saviour. He has been variously denounced as a pirate, a terrorist and a deluded crackpot who is one day going to cause a terrible tragedy. Is he really saving the whale? Or is he actually hardening opinion in Japan, making it less likely that the whaling fleets will return to port?

Watson is typically unequivocal about the rights and wrongs of his actions. “We cannot sit upon our ass, doing nothing as gentle creatures die,” he said before his ramshackle “Neptune’s Navy” set off for its annual rendezvous with the Japanese whalers.

“When people call us pirates, I really don’t have a problem. We’re pirates of compassion in pursuit of pirates of profit.”

He certainly sports a piratical air with his unruly white hair and his homemade captain's uniform, bristling with gold braid. He isn’t a real captain, but there is no doubting he is in complete control of the Sea Shepherd organisation, which claims 40,000 supporters worldwide, with 12,000 active members, an annual budget of $2m and a full-time staff of 10.

Nor is there doubt about the passion he inspires among a startling range of celebrity admirers, from Mick Jagger to Uma Thurman. “He’s one of the gutsiest guys on the planet,” said the actor Martin Sheen, who gushed to The New Yorker magazine last year that he was “grateful” to Watson for his “commitment and his courage and his daring and his humanity”.

Yet among those who should be his allies, he is regarded as an irritant who gets in the way of the environmental movement’s goals. Offers of cooperation are rejected.

Last week Greenpeace, having found the Japanese whaling fleet, refused to give Watson’s group the coordinates for its location. “It’s operational policy; we just don’t do it,” said the group. Last year, when the situation was reversed, Sea Shepherd had provided the coordinates for them.

Greenpeace insists that nonviolence is key to getting its message across. Willie Mackenzie, the organisation’s oceans campaigner, said violence “doesn’t progress the argument anywhere for us”. He added that Greenpeace had detected a previous shift in Japanese opinion on whaling, but the government in Tokyo had always been quick to label protests at sea as terrorist activity, stirring up public resentment.

“That’s why we’re careful to use nonviolent protests,” Mackenzie said. “They’re determined to group us together as terrorists, so the less ammunition we can give them towards that, the better.”

Watson was kicked off Greenpeace’s board in 1977 after losing his temper during a save-the-baby-seals protest in Newfoundland. He had attacked a sealer and thrown his skins in the water. Watson was seen as too passionate and too egotistical for his own and the organisation’s good. The feud has continued ever since.

Watson took on the role of freelance maritime vigilante. He scuttled two whaling ships in Reykjavik harbour in 1986 and spent 80 days in prison in the Netherlands after trying to sink a Norwegian vessel. At one point he dropped paint-filled light bulbs on a Soviet trawler in the northern Pacific; he has also flung smoke-bombs, stink-bombs, rancid pie filling and even stale chocolate cake at whaling vessels.

Last year he launched “Operation Asshole” in which his boats would eschew the typical Greenpeace tactic of putting themselves peacefully between the whaler and its prey. Instead the Sea Shepherd pursuit vessels would attempt to give the Japanese ship a “steel enema” – ramming his bows up its stern. They could not, however, get close enough.

His personal life was equally volcanic. Divorced three times, he was previously married to a Playboy model and a Greenpeace accountant. One of his volunteers reportedly described his management style as “anarchy run by God”.

One of the main targets of Watson’s ire is Dr Luis Pastene, a Chilean scientist at the Japanese Cetacean Research Institute (CRI). Pastene is described by Watson as the “Dr Mengele of whales”. The CRI is the central plank of what many world governments agree is Tokyo’s highly dubious interpretation of an exception to the International Whaling Commission moratorium, which allows sovereign nations to kill whales for research purposes only.

As one of the world’s most prolific whaling nations, Japan has long argued that its Antarctic hunts are necessary to monitor the movements of whale populations, to study relations between different types of whale, and to see how they are being affected by pollution.

All this science will apparently require the slaughter of at least 900 whales during the current hunting season. What made this year’s hunt so controversial was that, for the first time since the 1960s, the Japanese harpoons planned to target humpback whales, as well as minke. But at the beginning of last month the Japanese government bowed to international pressure and gave the humpbacks a stay of execution.

Most of the whale meat from the annual hunt ends up on Japanese dinner tables. Lord Rooker, the food minister, dismissed last week as “preposterous” and “indefensible” the Japanese claims that the “research” requires such mass killing.

Watson takes the view that Rooker, like most politicians, is an impotent nobody who will do nothing significant to help the whale. He mocks Pastene as a “whale vivisector” who pretends to be studying whale parts while merely acting as a cover for commercial whaling.

Nobody doubts the gleeful savagery of Watson’s invective, or the perverse cunning of his inflammatory strategy of causing as much trouble as possible. If some of his wilder claims aren’t quite supported by facts, at least he is making it impossible for governments to sweep the whaling issue aside.

All this came to a head amid last week’s Southern Ocean shenanigans. An Australian, Benjamin Potts, 28, and the Briton, Giles Lane, 35, sat at the back of an 18ft Zodiac as it sped towards the Yushin Maru.

The weather was bright and calm, and the two Sea Shepherd volunteers tossed ropes over the Japanese ship’s side and scampered up “like spiders”. It was a surprise to nobody that they were promptly seized, allowing Watson to denounce the Japanese as “terrorists”. His men were only trying to deliver a letter, he said.

The ensuing standoff was resolved after the arrival of an Australian vessel, the Oceanic Viking, which was supposed to be monitoring the Japanese fleet but which ended up ferrying Watson’s stormtroopers back to their mother ship.

Yesterday Watson accused the Australians of diverting the Steve Irwin away from the whaling grounds when it returned the two men. “Australian Customs deliberately led us away from the [Japanese] fleet and Greenpeace is guarding the coordinates like the crown jewels to prevent us relocating the whalers,” he said.

There were signs last night that if that was the intention, it had failed. The Japanese complained that their fleet had suffered another hounding from Sea Shepherd activists. A spokesman denounced it as “an inhumane terrrorist attack” and demanded that the Australian government seize the Steve Irwin.

Watson’s snort of derision was loud enough to scare a penguin. “People have got to stop thinking about the Japanese as some sort of legitimate operation,” he said by satellite phone from his ship last week. “These people are no different from elephant poachers in Africa or tiger poachers in India.”

He intends to harass the Japanese fleet for at least another week. It is possible that his actions may save a few whales, but his main mission – of provoking chaos and attracting attention – has already been an outstanding success.

Additional reporting: Christopher Thompson and Paul Ham in Sydney

The cows of the sea

Though they possess social skills that humans associate with intelligence, whales are no smarter than your average pet, according to many experts.

Tony Martin, head of the marine mammal section of the British Antarctic Survey, describes blue whales as “the cows of the sea”. He said: “They graze as they go along so they don’t have to outwit their prey, just like a cow doesn’t outwit the grass.”

What’s more, although whales communicate, they do not speak: “They have contact calls, but that’s not language,” said Martin. “We’ve never been able to observe anything like Mum saying to Dad, ‘Have you seen Johnny recently?’ ” Predatory toothed whales, which include killer whales and dolphins, are certainly considered more intelligent than plankton-grazing species such as the blue whale, but no more so than other animals.

“Humans are in awe of whales and they are incredible in so many ways, but in terms of intelligence, it is hard to say they are special,” said Martin. “I wouldn’t rate them any higher than a pet cat.”

Elizabeth Gibney

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