Greenpeace says Nauru's banning of vessels from offloading their catch to a mothership is only the first step to stop illegal fishing in the Pacific.
Nauru has issued a blanket ban on transhipments in its exclusive economic zone, after an alleged illegal operation by a Taiwanese ship caught near its waters by Greenpeace last week.
The practice involves vessels transferring their catch to a bigger ship out at sea which allows them to stay in ocean fishing grounds for years on end and dodge mechanisms which monitor their catch.
A Greenpeace campaigner with the Rainbow Warrior II, Lagi Toribau, says banning the practice is the right move, but Pacific nations lack the resources to properly monitor the practice.
"One of the Pacific Island nations, that's Kiribati, their entire national waters is well over three million square kilometres of ocean, that's bigger than the continental USA if you put it in, and they only have one patrol boat."
Mr Toribau says some of the countries also do not have enough fuel to power their patrol boats.
He says support from neighbouring countries such as Australia, New Zealand, the United States and Taiwan to monitor fishing is encouraging, but Pacific countries also need to recognise the bargaining power of their ocean resources and impose harsher restrictions on fishing vessels.