The worst of the pirate fishermen come from Spain, in particular from a family-owned Galician shipowning enterprise, Vidal Armadores S.A.

This company came to public notice in August 2003 when an Australian Customs and Fisheries patrol vessel, Southern Supporter, spotted one of its vessels taking toothfish in Australian territorial waters in the southern Indian Ocean.

Ordered to stop, Viarsa 1 fled.

The captain, Ricardo Mario Ribot Cabrera, led a three-week chase through huge seas and icebergs.

As the pursuit moved west, three other boats joined in: a southern African salvage tug John Ross, an icebreaker Agulhas, and a Falkland Islands-based British fishery patrol boat Dorada. On August 28, after travelling 7200 kilometres, the little fleet surrounded Viarsa 1 southwest of Cape Town.

The boat was put under arrest and taken back to Fremantle in Australia.

It had 97 tonnes of toothfish on board. Australian authorities, having won the world's longest sea chase, then botched the case in court. A jury found the evidence of fishing violations was only "circumstantial" and that this raised enough doubt to prevent a conviction.

READ MORE: Navy unable to board fishers' boats

In 2011, the US Center for Public Integrity's International Consortium of Investigative Journalists (ICIJ), which bills itself as one of America's oldest and largest non-partisan non-profit investigative news organisations, published an article on Viarsa 1.

It had turned out that Vidal Armadores was linked to more than 40 alleged cases of illegal fishing.

ICIJ journalists had confronted Manuel Antonio Vidal Pego, the company's co-owner, who denied being a pirate fisherman.

"You can see I don't have a hook, a parrot on my shoulder or a wooden leg," he said.

"We want to erase a story that has never been erased because there's always someone trying to revive it. So much damage has been done by the bad press, we've gone from a dynamic company to nothing."

Vidal Pego claimed his ships only took toothfish legally, but ICIJ found that government agencies and international regulators had repeatedly pursued Vidal Armadores.

The company and its affiliates had clocked up fines around the world of more than US$5 million ($6.5 million). At the same time, the Spanish government and the European Union had granted Vidal Armadores at least €8.2m in subsidies.

In 2005, another pirate toothfishing ship the Ross, one of the world's worst, was spotted in Australia's subantarctic marine territory.

It was flying the flag of Togo, a West African country of six million people.

Eighteen months earlier the same boat, then named Alos, had been caught - by legal fishermen - illegally fishing at Heard Island, a remote Australian territory in the Southern Ocean.

Following a boat's changes in ownership can be fascinating detective work, but for law enforcement officials around the world, required to be clear about what they're doing, it is a nightmare.

The complex subterfuge involved in toothfishing was exposed in May 2008, when a Namibian-flagged ship, Paloma V, docked in Auckland with 98 tonnes of toothfish, 83 tonnes of nurse shark, and 50,000 litres of fish liver oil on board. It was also carrying shark fins from Lord Howe Rise and South Tasman Rise, although it had no right to fish for these.

Paloma V was half-owned by a Uruguayan subsidiary of Vidal Armadores.

Its captain, Jose Antonio Paz Sampedro, signed a declaration that he had not been involved in illegal fishing.

Ministry of Fisheries (now Primary Industries) officers Phil Kerr and Dominic Hayden inspected the ship and, unusually, cloned copies of its three computers' hard drives.

These showed that Paloma V had paid for the provisions of pirate boats elsewhere.

There were emails detailing the sharing of bait, fuel and crew.

There were even photos in which Paloma V moved supplies on to a vessel called Chilbo San 33, which, when later spotted by the RNZAF in the Ross Sea in February 2011, had a new name, Xiongnu Baru 33, and a North Korean flag.

The computers also revealed that Paloma V had been using a particular software which the inspectors assumed showed coordination of illegal fishing in the Southern Ocean.

Screen captures showed Paloma V working with boats called Belma, Eolo, Galaecia and Hammer in an area around the South Tasman Rise.

Fisheries decided to deny Paloma V unloading rights and report it to CCAMLR as an illegal fishing boat.

This led to a High Court hearing in Wellington. Omunkete Fishing (Pty) Ltd, a Namibian company with Spanish owners, said it had purchased Paloma V for €7m - a book entry, with no cash changing hands - and had permission to catch toothfish.

The company had not intended to land a catch in New Zealand, but at some point the ship had ended up in the area and sought to do so at Auckland.

The High Court accepted evidence from the Ministry of Fisheries that Paloma V and the two companies that owned it had interests in the operations of at least five illegal toothfishing vessels.

Paloma V, the ministry said, was "operating as part of a larger fleet of vessels flying different flags engaged in IUU fishing activities".

Although the ship was detained for eight days and not allowed to unload, it got off with a warning.

Since its release, it has been seen fishing in Antarctic waters under the flags of Mongolia, Belize and Cambodia, although its ownership can always be traced back to the Spaniards.

While the case of Paloma V shed light on the various ruses used by companies to hide their activities, it also showed how relatively powerless citizens are in stopping the plundering of the seas.

It gets worse.

Vidal Armadores features frequently in discussions of pirate fishing.

At least nine of the company's vessels have been convicted of illegal fishing for shark and toothfish.

But, as the lobby group Oceana has ruefully noted, despite Vidal Armadores' notoriety and the formal blacklisting of its vessels by international fisheries management organisations, it has received subsidies of nearly €10m from the European Union. Even after its convictions, it was provided with subsidies by the autonomous government of Galicia to support construction of a processing factory.

In February 2011, an RNZAF Orion photographed two North Korean-flagged toothfishing boats in the Ross Sea.

One, Xiongnu Baru 33, was using deep-sea gill nets - banned internationally because "ghost fishing" by nets that are lost or discarded has detrimental effects on marine life.

The second ship, Sima Qian Baru 22, had the usual labyrinthine history.

As Vidal Armadores' Dorita it had flown the Uruguayan flag before being blacklisted as an illegal fishing vessel.

It had known other lives as Magnus, flagged to Saint Vincent and the Grenadines, and the previously mentioned Eolo, flagged to Equatorial Guinea.

There were other names: Thule, Red Moon, Black Moon, Ina Maka, Galaxy and Corvus. The list underscored the way pirate ships operate: some names are simply painted on as soon as a patrolling aircraft or ship has passed by.

On December 19, 2010 an Australian Customs vessel, Ocean Protector, detected a fishing boat in the Southern Ocean. The boat's home port, Lome, was painted on its stern and it was flying a Togo flag.

However, there was no flag of registration on its mast, as required by international maritime law.

The call sign on its side identified it as Zeus, a banned vessel previously registered in Sierra Leone and Japan and known as Triton 1 and Kinsho Maru 18. A check revealed Togo had removed its registration.

The Australians informed the ship's master they were going to board because of the lack of a mast flag. The crew hauled up a Togo flag. The Australians told them they had been struck off as pirates. They hauled up a Mongolian flag and painted Lana along the side of the ship. The master agreed to an inspection but asked for time to prepare. The crew painted over the words Zeus and Lome, and the boat headed away.

This article is an extract from The Catch: How fishing companies reinvented slavery and plunder the oceans (Awa Press), by Michael Field