Illegal Fisheries Protest in South Korea. 10/07/2014 © Paul Hilton / Greenpeace

It's incredible to watch the unravelling of the tangled web illegal fishers have woven around their dirty business. Fishing companies have created elaborate webs of deception stretching from Korea to New Zealand, Argentina to South Africa, and as far south as the icy Antarctic waters. But no matter how deep they try to bury their crimes, eventually they will come back to haunt them.

Those crimes include a blatant disregard of laws and fisheries agreements, the reckless and abusive treatment of crew, and the plunder of fish for greed and short term profit. South Korea's distant water fishing fleets are responsible for several recent cases that include all the above crimes, and have cost many human lives.

This week, the Korean vessel Insung 3 was met with an unexpected reception when it returned to port in Busan and was branded ILLEGAL by Greenpeace activists. The action highlighted its recent conviction for illegal fishing for toothfish in Argentinian waters. The ship is believed to be carrying some 60 tonnes of illegally caught toothfish.

But that ship is just part of a bigger picture. The conviction came after the vessel and its sister ship Insung 7 were locked in a dispute with the Korean Government. Both vessels had been showing suspicious behaviour inside Argentina's waters, where they had no permission to fish. (The Insung 7 has previously been fined for fishing four times its catch limit in Antarctica's Ross Sea). The Korean Government refused to issue catch certificates but the vessels continued to fish. Eventually, the company attemped to use the ships' crew as pawns, telling the government they wouldn't put in to port until they were issued catch certificates for the fish they had already caught.

Despite the company's attempts at blackmail, no catch certificates were issued. After forcing their crews to endure more than year at sea, the vessels finally put in to Montevideo in Uruguay, where Greenpeace branded Insung 7 'illegal'. Both vessels were subsequently fined and suspended from fishing by the Korean Government, but with fines of only US$1,500 per vessel and 30-60 days suspension, the punishment is hardly going to leave Insung Corporation out of pocket, let alone deter other pirate fishers.

Using a ship's crew as bargaining chips in the blackmarket fish trade is shocking, but dig deeper and you see an even darker picture of the company's disregard for human lives, mirrored only by the depths of its disregard for the environment.

In 2010, another of the company's vessels, Insung 1, sunk in rough Antarctic waters, killing half of the crew. A coroner's inquiry held in New Zealand concluded that the tragic disaster was the result of negligence by the vessel's master and officers, along with insufficient safety gear, and emergency communications only made in Korean.

The Korean Government has told Greenpeace the Insung 7 is going to be "retired." Due to be scrapped, Insung 7 (along with another company vessel Insung Ho) has transited to South Africa, where Greenpeace has called for the South African Government to inspect the vessels. Greenpeace hopes this will shed light on the sketchy fishing operations of the fleet, in the same way that New Zealand's inspection of toothfish vessel Paloma V in 2008 revealed a network of licensed and illegal vessel operating together in the Southern Ocean.

To further complicate matters, Insung Corporation has aquired another vessel Oyang 77 – now renamed Jille – from Sajo Oyang Corporation. This vessel comes with its own illegal fishing history, having been convicted of Illegal fishing in New Zealand and forfeited to the New Zealand Government.

The company Sajo Oyang has an equally bad track record. In addition to the conviction against Oyang 77, its sister vessel Oyang 75 was convicted of illegal fishing and was forfeited to the New Zealand government. It fled port before the trial, initially to the Indian Ocean but now fishing off Argentina, near the Insung fleet.

Yet another of the company's vessels, Oyang 70, sank New Zealand in 2010 with the loss of six lives. Again, the ship's master was found to blame for the tragedy. It was a case of pure greed, neglecting safety by attempting to haul in an excessively large catch that led to the sinking of the ship. Again, there was insufficient safety equipment and commands were given only in Korean, despite the crew being predominantly Indonesian and Filipino.

Both these fleets are implicated in the labour abuse scandals and accusations of slavery at sea that have been levelled at foreign vessels operating, under charter to New Zealand fishing companies, in New Zealand. Although the New Zealand government has made a belated commitment to end the use of foreign charter vessels (while shamefully allowing these practices to continue until May 2016) the scale of their operations makes it clear that this is a problem that must be addressed internationally.

Greenpeace is calling for action to end slavery and labour abuse at sea. This will require countries and seafood industry players to crack down on companies that operate with blatant disregard for the law, human lives and ocean health. The vessels mentioned here are listed on the Greenpeace pirate fishing blacklist, and seafood retailers must ensure that they do not trade with any company on that list.

All traders and retailers of seafood must ensure they are fully aware of the source of the fish they sell. They must be certain it doesn't come from a blacklisted company and hasn't been transshipped at sea (where catches are transferred between vessels, potentially hiding their origin). If traders and retailers don't act, they may find they are selling the illegal and unethical catches of vessels such as these.

Karli ThomasKarli Thomas is senior oceans campaigner with Greenpeace Aotearoa New Zealand. She has spent many months at sea in fishing grounds, from the Mediterranean Sea to the Pacific Ocean and as far south as Antarctic waters. Karli coordinates Greenpeace's pirate fishing blacklist and works on illegal, unreported and unregulated fishing.