The world's largest fishing factory freezer ship and its fleet of catcher trawlers has passed through New Zealand's exclusive economic zone around the Kermadec Islands.
The Chinese-owned Lafayette, a 49,367 gross ton converted oil tanker flying a Russian flag, uses giant hoses to suck catches from its attendant trawlers.
It is targeting South Pacific jack mackerel on the high seas, vital in the farmed salmon industry.
The fishery is under heavy international pressure.
Lafayette was first spotted last week near Australia's Norfolk Island.
Yesterday the US based volunteer group SkyTruth - which monitors ships via their automatic identification systems (AIS) and radar satellite images - picked up Lafayette in the Kermadec EEZ.
SkyTruth is monitoring on behalf of the US Pew Institute's Kermadec Initiative which wants to turn the area into an international marine sanctuary.
Lafayette passed though the zone south of Raoul Island and then changed course.
At 6.06am today Lafayette was about 1000 kilometres east of the North Island's East Cape, likely to be heading to fishing grounds southeast of French Polynesia.
Lafayette has its AIS turned on, allowing it to be tracked. The six trawlers working with it, all Peruvian-flagged, have switched their AIS off meaning it is not easy to find them or to know what they are doing.
The trawlers are registered with the Wellington based South Pacific Regional Fisheries Management Organisation (SPRFMO) and allowed to take 8300 tons of mackerel.
Lafayette is owned by Hong Kong-based, Bermuda registered Pacific Andes International.
It spent US$100 million ($120 million) in 2008 remodelling the former tanker. It is the only Russian-flagged ship in the region and in 2010 it reported taking 41,315 tonnes of mackerel east of New Zealand, an increase of 136 per cent from the previous year.
As the fishery was collapsing, other nations accused Russia of faking its statistics in order to get a better sized quota later.
SPRFMO met in Auckland last year and Russia was challenged over what Lafayette was really doing. Russia was stripped of its quota. It won it back on appeal and this is the first time since that row that the super-factory ship has returned.
Pacific Andes told Fairfax Media the ship was heading for the jack mackerel fishery, using prevailing currents to get there economically.
"It is not a fishing vessel and fishing quotas are set by the SPRFMO for the catcher fishing vessels it supports, and those quotas are not exceeded," Pacific Andes said.
In 2012 an investigation by the International Consortium of Investigative Journalists found giant fishing vessels were responsible for a 90 per cent decline in the South Pacific jack mackerel fishery.
The head of Pacific Andes, Ng Joo Siang, told ICIJ the company had kept Lafayette under a Russian flag because it perfected an old Soviet idea of a mother ship that stays put, sucking in fish to process from a fleet of catcher vessels.
Lafayette can process 1500 tonnes of fish a day.