The South Pacific Regional Fisheries Management Organization, or SPRFMO, decided to keep on its list of banned vessels the world's biggest fishing ship, the Peruvian-flagged Damanzaihao, a step praised by the international conservation group Oceana.

The decision comes almost one year after the ship, which has changed flags several times and is also known as the Lafayette, was banned from Pacific waters despite an appeal by its owner, Sustainable Fishing Resources.

"The Damanzaihao presents a real danger for oceans due to its huge storage capacity," Liesbeth van der Meer, director of the Fisheries Campaign with Oceana Chile, told reporters.

"Controlling illegal fishing is urgent for the sustainability of fisheries and, in particular, when dealing with overfished species, such as Pacific mackarel, which have great commercial and social relevance," Van der Meer said.

In February 2015, SPRFMO added the Damanzaihao to its lists of vessels involved in illegal, undeclared and unregulated fishing, after detecting an unauthorized trans-shipment and false reporting to authorities about cargo of frozen Pacific mackarel.

The Peruvian Production Ministry, acting on the designation, cancelled the fishing permit for the 49,367-ton ship, which now flies the Peruvian flag, and slapped a fine on Sustainable Fishing Resources.

The company appealed the decision and Peru's courts voided the fine but ordered a new process to impose new penalties, which will keep the Damanzaihao on the pirate ships' list until 2017.

The vessel, according to Oceana, is able to process up to 547,000 tons of fish a year, surpassing the limits on the Pacific mackarel catch, which is regulated because it is an endangered species.

Refurbished in 2008, the Damanzaihao was a tanker transformed into the world's biggest fishing boat, operating as a mother ship storing and transporting the catch from trawling fishing fleets.

The cargo is sorted, processed and frozen on board for transporation to distant markets.