The environmental group said activists on the Greenpeace ship Esperanza took action Sunday against the U.S. fishing vessel Cape Finisterre in an area known as the Pacific Commons. Activists painted the side of the U.S. vessel with the words "Tuna overkill."

Greenpeace said about 60 percent of the world's tuna stocks come from the Pacific. Experts have said bigeye and yellowfin tuna are in danger of becoming over-fished.

Activist Lagi Toribau said advances in technology mean large ships from as far away as the United States and Europe can catch as much fish in two days as the fishers of some small Pacific Island countries catch in a year.

"As tuna catches in other oceans have declined because of overfishing, the floating factory ships are looking to move into the Pacific, making it harder for local fishing fleets to catch tuna which is a vital food source for the region," Toribau said in statement.