It had taken five days to arrange this meeting. Somali pirates are hard to track down, constantly moving around and changing phone numbers. Days earlier, frustrated and eager to begin interviewing, I had naively suggested approaching some suspected pirates on the streets of Garowe, a rapidly expanding city at the heart of the pirates' tribal homeland. Habitually munching on narcotic leaves of khat, they are easy enough to spot, their gleaming Toyota four-wheel-drives slicing paths around beaten-up wheelbarrows and pushcarts. My Somali hosts laughed, explaining that to do so would invite kidnapping, robbery, or, at the very least, unwanted surveillance. In Somalia, everything is done through connections – clan, family or friend – and these networks are expansive and interminable. Warsame, my guide and interpreter, had been on and off the phone for the better part of a week, attempting to coax his personal network into producing Abdullahi "Boyah" Abshir. Eventually it responded, and Boyah presented himself.

I was being taken to a mutually agreed meeting place in an ageing white station wagon, cruising out of Garowe on the city's sole paved road. My two UN-trained bodyguards, Said and Abdirashid, perched attentively in the back seat and in the rear-view mirror was a sleek new Land Cruiser, a shining symbol of the recent money pouring into Garowe. It carried Boyah, Warsame and another fixer.

Other than our two vehicles, the road was empty, stretching unencumbered through a stony desert dotted with greenish shrubs. The thought that I was being taken to be executed in a deserted field – the unfortunate product of too many Las Vegas mob movies – rattled around in my head for a few seconds.

We arrived at our destination, a virtually abandoned roadside farm 15 kilometres outside Garowe. Boyah had recently contracted tuberculosis, and Warsame insisted that we meet him in an open space. As we stepped out of our respective vehicles, I caught my first glimpse of Boyah. He looked to be in his early 40s, immensely tall and with an air of menace about him; the brief, calculating glance with which he scanned me left the distinct impression that he was capable of chatting amiably or robbing me with the same equanimity. He was wearing a ma'awis, a traditional sarong-like robe of a clan elder, and an imaamad, a decorative shawl, was slung over his left shoulder.

Boyah turned immediately and loped down a dirt path. Threading his way through the mishmash of tomato plants and lemon trees that constituted this eclectic farm, he wove back and forth, like a bird looking for a roosting spot. Finally, he settled on a site in a cool, shady clearing, where an overhead thatching of branches had created an almost cave-like atmosphere.

Other than the farm's owner and his wife, no one was remotely close by, yet the bodyguards took up positions at either end of the clearing with an amusing military officiousness. I greeted him with the standard Salaam álaykum, and was not surprised when he and those around him responded with startled laughter before quickly offering the formulaic response: Álaykum salaam. Somalis were routinely astonished when I demonstrated the slightest knowledge of their culture or language – even a phrase that they shared with the entire Islamic world.

As I forced out my first question through Warsame, I hesitated to use the word "pirate" to describe Boyah. The closest Somali translation of the word is burcad badeed, which literally means "ocean robber", a political statement I was anxious to avoid. In much the same way that revolutionaries straddle the semantic fence separating "freedom fighters" from "terrorists", Boyah and his brothers-in-arms did not like to call themselves "pirates" in their native tongue.

In an alliterative display of defiance, they referred to themselves as badaadinta badah, "saviours of the sea", a term that is most often translated in the English-speaking media as "coastguard". Boyah joked that he was the "chief of the coastguard", a title he invoked with pride. To him, his actions had been in protection of his sea, the native waters he had known his whole life; his hijackings, a legitimate form of taxation levied in absentia on behalf of a defunct government that he represented in spirit, if not in law.

His story was typical of many coastal dwellers who had turned to piracy since the onset of the civil war almost 20 years ago. In 1994, he still worked as an artisanal lobster diver in Eyl – "one of the best", he said. Since then, the lobster population off the coast of Eyl has been devastated by foreign fishing fleets – mostly Chinese, Taiwanese and Korean ships, Boyah said. Using steel-pronged drag fishing nets, these foreign trawlers did not bother with nimble explorations of the reefs: they uprooted them, netting the future livelihood of the nearby coastal people along with the day's catch. Today, according to Boyah, there are no more lobsters to be found in the waters off Eyl. So he began to fish a different species, lashing out at those who could out-compete him on the ocean floor, but who were no match for him on its surface. From 1995 to 1997, Boyah and others captured three foreign fishing vessels, keeping the catch and ransoming the crew. By 1997, the foreign fishing fleets had become more challenging prey, entering into protection contracts with local warlords that made armed guards and anti-aircraft guns regular fixtures on the decks of their ships. So, like all successful hunters, Boyah and his men adapted to their changing environment, and began going after commercial shipping vessels. They soon attracted others to their cause. "Boyah was a pioneer," one local journalist told me. "He showed the others the real potential of piracy."

"There are about 500 pirates operating around Eyl. I am their chairman," he said, claiming to head up a "central committee" composed of the bosses of 35 other groups. The position of chairman, however, did not imbue Boyah with the autocratic powers of a traditional gang leader. Rather, Eyl's pirate groups functioned as a kind of loose confederation, in which Boyah was a key organiser, recruiter, financier and mission commander. But would-be applicants for the position of pirate (Eyl division) had to come to him, he claimed. Boyah's sole criteria for a recruit were that he own a gun and be "a hero, and accept death" – qualities that grace the CVs of many desperate local youth. Turnover in Boyah's core group was low; when I asked if his men ever used their new-found wealth to leave Somalia, he laughed and shook his head. "The only way they leave is when they die."

Boyah, who claimed to have hijacked more than 25 ships, told me that he and his men did not discriminate, but would go after any ship hapless enough to wander into their sights. And despite their ostensible purpose of protecting Somali national waters, during the heat of the chase they paid no regard to international boundaries, pursuing their target until they caught it or it escaped them. Boyah separated his seafaring prey into the broad dichotomy of commercial and tourist ships. The commercial ships, identifiable by the cranes visible on their decks, were much slower and easier to capture. Boyah had gone after too many of these to remember: "a lot" was his most precise estimate.

The basic strategy was crude in its simplicity. In attack groups spread across several small and speedy skiffs, Boyah and his men approached their target on all sides, swarming like a waterborne wolf pack. They brandished their weapons in an attempt to frighten the ship's crew into stopping, and even fired into the air. If these scare tactics did not work, and if the target ship was capable of outperforming their outboard motors, the chase ended there. But if they managed to pull even with their target, they tossed hooked rope ladders onto the decks and boarded the ship. Instances of the crew fighting back were rare, and rarely effective, and the whole process, from spotting to capturing, took at most 30 minutes. Boyah guessed that only 20% to 30% of attempted hijackings met with success, for which he blamed speedy prey, technical problems and foreign naval or domestic intervention. The captured ship was then steered to a friendly port – in Boyah's case, Eyl – where guards and interpreters were brought from the shore to look after the hostages during the ransom negotiation.

Once the ransom was secured – often routed through banks in London and Dubai and parachuted like a special-delivery care package directly onto the deck of the ship – it was split among all the concerned parties. Half the money went to the attackers, the men who actually captured the ship. A third went to the operation's investors: those who fronted the money for the ships, fuel, tracking equipment and weapons. The remaining sixth went to everyone else: the guards ferried from shore to watch over the hostage crew, the suppliers of food and water, the translators (occasionally high-school students on their summer break), and even the poor and disabled in the local community, who received some as charity. Such largesse, Boyah told me, had made his merry band into Robin Hood figures among the residents of Eyl.

Boyah's moral compass seemed to be divided between sea and shore; he warned me, half-jokingly, not to run into him in a boat, but, despite my earlier misgivings, assured me that he was quite harmless on land. "We're not murderers," he said. "We've never killed anyone, we just attack ships." He insisted that he knew what he was doing was wrong, and, as evidence of his sincerity, relayed how he had just appeared on the local news radio station, Radio Garowe, to call a temporary ceasefire on all pirate activity. Though I was sceptical that he wielded the authority necessary to enforce his decree over a coastline stretching almost 1,600km, Boyah stressed that the decision had been made by the central committee – and woe to those who defied its orders. "We will deal with them," Boyah promised. "We will work with the government forces to capture them and bring them to jail."

Subsequent events quickly proved that Boyah's radio statement was just so much background noise. Just days after his announced ceasefire, a pirate gang in the Gulf of Aden committed the first commercial hijacking of 2009, capturing a German liquid petroleum tanker along with her 13 crew members. The Central Committee has wreaked no vengeance on those responsible.

Boyah himself had not gone on a mission for over two months, for which he had a two-pronged explanation: "I got sick, and became rich." His fortune made, Boyah's call to end hijackings came from a position of luxury that most others did not enjoy. I questioned Boyah on whether his ceasefire had been at least partially motivated by the Nato task force recently deployed to deal with him and his colleagues.

"No," he said, "it has nothing to do with that. It's a moral issue. We started to realise that we were doing the wrong thing, and that we didn't have public support." Their public support, according to Boyah, had taken a plunge last summer when a delegation of local clan and religious leaders visited Eyl and declared to the local population that dealing with pirates was haram – religiously forbidden.

Throughout our conversation, Boyah had been gazing off into space between my questions, looking bored. Soon he grew restless, mumbling discontentedly as he glanced at the two o'clock sun that "the day is already over". I managed to slip in one final question, asking him for his most exhilarating high-seas chase. He brightened up and launched into the story of the Golden Nori, a Japanese chemical tanker he had captured in October 2007 about 14km off the northern Somali coast.

"Almost immediately after we had boarded the ship the US Navy surrounded it," said Boyah. The destroyer USS Porter was the first to respond; Boyah's memory, perhaps augmented with time, recalled seven naval vessels encircling him. The swiftness and gravity of this response nearly spooked Boyah's men into fleeing the ship and attempting an escape in their overmatched fishing skiffs. Fortunately for them, the Golden Nori was carrying volatile chemicals, including the extremely flammable compound benzene. With mirth lighting up his face, Boyah told me how the American ships were afraid to fire on the ship for fear of detonating its payload.

The stand-off dragged on through November and into December. "We ran out of food," Boyah said, "and we almost abandoned the ship so we wouldn't start eating the crew." Attack helicopters whirring overhead, Boyah ordered the ship into the harbour at Bosaso, Puntland's most populous city. In case the Nori's explosive cargo proved an insufficient deterrent, Boyah added the defensive screen provided by the city's civilian population.

His perseverance paid off. After lengthy negotiations aboard an American vessel, a pirate delegation finally secured a generous ransom of $1.5m in exchange for releasing the Nori and its captive crew. As part of the deal, the American military guaranteed Boyah and his team safe passage off the hijacked ship. Puntland security forces, waiting on shore to arrest the brigands, could only watch as US Navy helicopters escorted the pirate skiffs to land and allowed the pirates to disembark.

The Golden Nori was one of the first major commercial vessels hijacked in the Gulf of Aden, before the international community had truly become aware of the problem. During this period, foreign navies tended to give pirates a slap on the wrist: their weapons and boats were impounded or destroyed, and they were released. More recently, states have begun to use the international legal instruments available to them – particularly a UN Security Council resolution permitting foreign entry into Somali waters – much more rigorously. Foreign warships are increasingly detaining and rendering suspected pirates to neighbouring countries to face justice.

Boyah had experienced this approach as well. In April 2008, his gang seized a rare prize, a speedy French luxury yacht, Le Ponant, on route from the Seychelles to the Mediterranean. After delivering a ransom and freeing the hostages, French attack helicopters tracked the pirates inland to the village of Jariban. On the orders of President Nicolas Sarkozy, French commandos launched Operation Thalathine: special forces snipers disabled the pirates' getaway vehicle and captured six of the brigands, subsequently flying them to Paris to face trial.

Boyah's men had been captured or killed with increasing frequency in recent days (his brother was sitting in a Bosaso prison), but it did not matter. Imprisoning them was like trying to use a bailing bucket to drain the ocean: for each pirate captured by the authorities, there were dozens of desperate young men on shore ready to rush in and fill the void. Until there are alternative meaningful occupations on land, this is unlikely to change.

Boyah had become visibly irritable, and the next pause in my questioning heralded the end of the interview. His bothersome task completed, he rose and started heading back to where the vehicles were parked. As he walked, Warsame casually sidled up to Boyah and slipped him a folded $100 bill; suddenly the puzzling incongruity between Boyah's irascible manner and his willingness to speak to me was perfectly clear. "These pirates always need money, you know, to buy khat," said Warsame.

Meanwhile, Boyah had leaked out ahead of the rest of us, bounding up the trail alone. Warsame and I gaped as he effortlessly cleared the metre-wide knee-high bramble patch separating the farm from the shoulder of the highway. With gigantic strides, he ran up the slope to the cars and waited impatiently as we slowly climbed up after him. It was time for his khat.