Greenpeace said Thursday they boarded a Taiwanese ship allegedly operating illegally near Papua New Guinea, finding bags of shark fins onboard in what could be the latest example of the lucrative poaching trade in the region.

The reported discovery of 75 kilogrammes (165 pounds) of shark fins by the activist group on Wednesday night came as regional leaders met in Port Moresby for the Pacific Islands Forum and worked on a sustainable fisheries roadmap.

Global seas have been fished to dangerously low levels, according to independent panel the Global Ocean Commission, hitting fishing-dependent countries, such as in the Pacific where the multi-billion dollar tuna trade is an economic lifeline for some.

"It shows the extent to which illegal fishing is out of control in the high seas, and that more needs to be done to help Pacific nations with enforcement," Lagi Toribau of Greenpeace Australia Pacific said in a statement.

Greenpeace said the Shuen De Ching No.888, reportedly a Taiwanese-flagged tuna longliner, was operating in international waters near PNG when activists boarded it.

Suspected poaching vessels that ply the high seas, which fall beyond national jurisdictions, have challenged efforts to clamp down on illegal fishing as they suffer from a lack of oversight, the commission has said.

The group claimed the vessel had no fishing licence and had been reported to the Taiwan's fishery agency, although it did not receive a response.

"The Taiwanese government must order this illegal vessel to stop fishing and return to port immediately for a full and transparent investigation," Toribau added.

Taiwanese officials were not immediately available to comment on the claims.

Tuvalu's Elisala Pita, who heads up the Fisheries Ministerial group under the forum, told Pacific representatives at the talks Wednesday that most of the region's tuna was being caught by foreign vessels, with "90 percent taken out of the region for processing".