Samoa's proposal to list the blue shark as under threat has been accepted by the 12th conference on the Convention on Migratory Species in the Phillipines.
The conference acknowledged the shark would benefit from collaborative conservation measures.
Gillian Shirley Tuagalu, from Samoa's Ministry of Natural Resources, said the blue shark has been hunted by developed countries from outside the Pacific reducing its numbers to depressingly low levels.
The blue shark is the most frequently-caught shark globally.
Ms Tuagalu said suggestions it was being harvested sustainably, stem from inherently inaccurate fisheries stock assessments.
She said stock data is recorded by fisheries observer who are only on board about five per cent of longline vessels in the Pacific.
"Samoa has therefore opted to play a more prominent role in the global community to promote awareness, conservation - and importantly, to promote the link between conservation and sustainable fishing," Ms Tuagalu said.