Foreign Affairs Minister Murray McCully wants more surveillance of Pacific Island fisheries by New Zealand, the United States and Australia.
Mr McCully told the United States New Zealand Partnership Forum in Christchurch on Monday that tuna is the Pacific's most valuable economic asset and New Zealand wants to work more closely with the US to safeguard it.
He says about $400 million worth of fish is illegally taken from the Pacific every year.
Mr McCully says New Zealand is the largest provider of aerial surveillance of Pacific Island economic exclusion zones, and the US Coast Guard is a big help in those efforts.
But more must be done, he says: it's time for the two countries, along with Australia, to step up the surveillance and launch a comprehensive assault on the illegal fishing.