Thai officials say the rusting and decrepit 625-ton Taishan has left behind unpaid bills of )two million baht and has on board millions of dollars worth of illegally caught fish.
Thai authorities met on Wednesday to decide whether to send a navy ship in pursuit.
"We blinked and the ship was gone," Charoen Chamniklang, chief of the Royal Thai Customs and investigation suppression bureau told Phuketwan news.
In January the New Zealand navy said the ship, then called the Kunlun, used "evasive tactics" to thwart boarding attempts in Antarctic waters.
In February, crew of the Sea Shepherd Conservation Society's environmental observation ship Sam Simon said they spotted the ship using banned gill nets to haul in toothfish in a protected area of the Antarctic Ocean about 2400 kilometres south-west of Australia.
Weighing up to 120 kilograms, toothfish can sell for thousands of dollars.
The crew of the Sam Simon pursued the ship for six days before the allegedly rogue vessel peeled off and sailed to Australia's Cocos islands.
Australian Customs officials boarded the ship there and found a large cargo of frozen fish but said they could not lay charges as the crew and captain were on the high seas.
The ship then sailed to Phuket, arriving on March 6, where it was detained by authorities, apparently acting on a complaint from Australia.
The fish was hauled by truck to a deep sea port and put in frozen storage.
But Thai officials are believed to have allowed the cargo to be returned to the ship recently after storage fees were paid.
Since March most of the 30 people who were initially on board are believed to have left Thailand as Thai authorities continued to refuse permission for the ship to leave Phuket waters.
Thai officials were advised that Interpol was seeking information about the owners of the ship who had allegedly profited from illegal fishing.
As few as three crew members could now be on board, Thai officials believe.
Over 42 years the ship had also been called the Chang Bai, the Hongshui, the Corvus, the Galaxy, Red Moon and the Dorita under flags of Equatorial Guinea, Indonesia, Tanzania, North Korea, Panama and Sierra Leone, according to an investigation by the Los Angeles Times.
The Sea Shepherd Conservation Society is best known as the subject of the reality television show Whale Wars which documented its efforts to thwart Japanese whalers in the Antarctic Ocean.
Fishing in the Antarctic is regulated by the Convention on the Conservation of Antarctic Marine Living Resources, an international fisheries management body that comprises representatives from 24 nations and the European Union.
PHUKETWAN revealed exclusively today that the poacher vessel Taishan, also known as the Kunlun, has sailed in secret from Phuket waters.
Media Release: Interpol Wanted Poaching Vessel, Kunlun, And Its Illegal Catch Escape From Thailand
CAPTAIN Peter Hammarstedt and Captain Sid Chakravarty of Sea Shepherd have called on the Australian and New Zealand authorities and the relevant international enforcement agencies to ensure the missing Interpol Purple-listed toothfish-poaching vessel, Taishan, does not disappear after going on the run from Thailand.
The vessel has been under arrest in Phuket since March when it attempted to offload 182 tonnes of illegally caught Patagonian toothfish as grouper.
Since then, Thai authorities have used the country's national laws to keep the Taishan in port.
However, given the limited application of the law to international fisheries crimes, the vessel was subsequently reloaded with her catch and was kept at anchor for the past five months.
Citing the first possible opportunity, the vessel has eluded the local Thai authorities and escaped from custody on September 8, 2015.
The Operation Icefish campaign leaders warn there is high risk that the illegal cargo of toothfish will be sold on the black market, and that the poaching vessel will now return to Antarctica.
Reports that the catch of the Taishan's sister vessels, the Yongding and the Songhua, have disappeared without a trace, indicate that enough loopholes exist for the illegal vessels to continue to operate once they are no longer under the surveillance of authorities.
The Taishan, formerly called the Kunlun, was one of six internationally wanted toothfish poaching vessels targeted by Sea Shepherd in the organisation's epic Southern Ocean Defense Campaign, Operation Icefish.
The Kunlun has a long history of suspected fishing violations and is believed to have links to known Spanish crime syndicate, Vidal Armadores.
The vessel had been the target of several international incidents and run-ins with authorities in the lead-up to its detention.
In January, the Kunlun was one of three illegal fishing boats which brazenly fished in the presence of the New Zealand Navy after they were found engaged in fishing using banned gillnets in Australian waters, in the Southern Ocean.
In February, the vessel was again intercepted inside Australian waters, this time by the Sea Shepherd ship, Sam Simon. The Sam Simon then engaged in an eight-day pursuit of the poaching vessel, chasing it out of its hunting grounds in the Southern Ocean.
Later that same month, Australian Customs and Border Protection officers boarded the Kunlun in waters near the Cocos (Keeling) Islands in a feeble attempt to gather evidence of illegal fishing activity. The vessel was allowed to carry on to Southeast Asia with its illegal catch and gear.
Then in March, coordination between Sea Shepherd, international policing organisation, Interpol, and law enforcement authorities in Thailand, Australia and New Zealand resulted in the Kunlun being detained in Phuket.
Captain Hammarstedt, who is also the Chairman of Sea Shepherd Australia, has criticized Australia and New Zealand for their poor handling of the matter.
''When we criticised Australia and New Zealand for not arresting the Kunlun at sea, authorities in those two countries assured the international community that the most effective tool in the fight against these poachers was port state controls.
'' As the Taishan has now escaped from Thailand with its illegal catch in-tow, we are seeing this blunder for what it really is. If the vessel had been arrested by Australia or New Zealand, the catch would never have been returned.
''Instead, Australia and New Zealand's unwillingness to arrest the Kunlun and seize is catch at sea has allowed this poaching operation to continue, and to profit from its crimes,'' he said.
In recent months, Thailand has shown willingness to clean up its waters and drive out Illegal, Unreported, Unregulated (IUU) fishers out. However, without support from its wealthier Pacific neighbors, it appears that their efforts might fall short.
Captain Chakravarty said, ''An Interpol-listed vessel has slipped through the clutches of the Thailand authorities and is on the loose.
''The escape of the Taishan from the waters of Thailand clearly proves the resilience of the toothfish poaching industry and its willingness to defy national and international law enforcement agencies.
''With the catch of the sister vessels, the Yongding and the Songhua, assimilated into the legal markets, unless this Kunlun is found and arrested again, we expect another 182 tons of toothfish being traded the same way.''
Operation Icefish was Sea Shepherd's 11th Southern Ocean Defense Campaign, and the first to target IUU fishing operators in the waters of Antarctica.