On Thursday, the 82m vessel arrived at Leith wharf, Dunedin, to offload fish products at the Harbour Cold coolstore, restock, and refuel before departing on Saturday for the start of the southern blue whiting fishery.
A search was launched by the Rescue Co-ordination Centre New Zealand (RCCNZ) at 4.37am yesterday, after a radio beacon was activated 400 nautical miles east of Dunedin.
Shortly afterwards, a mayday call was picked up and relayed by Amaltal Atlantis, one of seven vessels in the area, which reported Oyang 70 had sunk.
Crew aboard Amaltal Atlantis did not see the fishing vessel sink, but were involved in the rescue of five life rafts, containing 45 of the 51 crew, who were from South Korea, Indonesia, the Philippines and China.
The bodies of three Indonesian crew men - aged 25, 35 and 38 - were recovered, while vessels in the area continued to search for a sixth life raft and the two remaining Indonesian crew and captain of Oyang 70, a South Korean national.
The 38-year-old vessel, one of the oldest fishing vessels operating in New Zealand waters, sank in conditions described as good, but extremely cold and foggy.
RCCNZ search and rescue co-ordinator Mike Roberts said it was understood fish-laden nets were being pulled up at the time the vessel capsized.
A Royal New Zealand Air Force P3 Orion covered the search area, but found no trace of the final life raft, and the search was called off at 5.40pm.
Mr Roberts said "sadly, the chances of survival are now nil".
The trio were not wearing full immersion suits and in 7degC water temperatures had a survival time of three hours.
"From what we understand, this was a catastrophic incident. Oyang 70 sank in just 10 minutes. It is incredible that so many survived without injury," Mr Roberts said.
A statement from the vessel's owner, Sajo Oyang Corporation, of South Korea, and the New Zealand charterer Southern Storm Fishing last night said while the matter was likely to be the subject of an official investigation, they "have no reason to believe that the sinking was in any way related to the condition of the vessel".
It had a full and current Maritime New Zealand safe ship management certificate, and complied with Korean survey standards which were consistent with those required of New Zealand vessels.
The company expressed its gratitude to those involved in the rescue and maintained its support for the families who had lost loved ones.
The Ministry of Foreign Affairs and Trade had liaised with foreign agencies to inform next of kin, and crew would also be supported by consulate officials who were kept informed by RCCNZ staff.
Tony Hazlett, chief executive of Nelson-based Amaltal, the deep-sea division of Talley's, said Amaltal Atlantis crew regularly practised rescue drills, and yesterday afternoon was still "actively looking for people".
The vessel would return to Christchurch once it had been released by the rescue co-ordinators.
Morale on board Amaltal Atlantis was good "given the circumstances", he said.
Mr Hazlett declined to speculate on reasons why the vessel capsized.
However Maritime Union general secretary Joe Fleetwood said it was "extremely disturbing" to hear the vessel sank in good conditions, and the incident was a maritime disaster.
Port Otago chief executive Geoff Plunket said the vessel was a frequent visitor to Dunedin and the company's thoughts were with the crew and Southern Storm, which charters the vessel.
