The Pacific Islands Forum Fisheries Agency says it is concerned about the United States threat to hugely increase its no fishing zone.
The US President Barack Obama recently signalled it would expand the no fishing zones around its Pacific territories by around seven times.
The move has been criticised by the US fishery council that governs the Pacific territories' fisheries.
The director general of the Forum Fisheries Agency, James Movick, says the US move could drive longliners into the southern seas, further depleting the very stock the small island states are trying to conserve.
"It's hard to see what precise management benefit would be obtained from that. What it will do though is encourage those fleets to relocate, including onto the high seas and other areas where they might be less subject to close management."
The director general of the Forum Fisheries Agency, James Movick.