University of Hawaii researchers say tuna numbers are growing in Hawaiian waters thanks to the establishment of a marine reserve 16 years ago.
Papahanaumokuakea, a 1.5 million sq km area, is a national American treasure inscribed in the UNESCO World Heritage.
Professor John Lynham said the reserve has replenished marine life.
"Over time the abundance of two areas is basically the same up until 2016 when the protected areas was not established. By 2017 you start to see an increase; by 2019 there is a large and statistically significant increase in the abundance of fish in that inner doughnut."
The bigeye tuna and the yellowfin are migrating species that are found in oceans around the world.
Lynham said statistics show that tuna numbers are coming out of the reserves in greater numbers only after the reserve was created proving a greater regenerative population.
"With ocean you can never be 100 percent certain of something. So there may be a very small chance that maybe in 2017 fish decided to migrate to the area of the Pacific Ocean and decided to do it again in stronger numbers again in 2019 even more.
"In our paper we acknowledge that there is somewhere in between a one in a thousand and a one in a million chances that maybe this happened randomly but what makes us confident is that we have never seen that happen before.
"We actually go back to the 1990s, and you just don't see year after year an abundance of fish in this particular area of the Pacific Ocean.
"It has never happened before and it started happening now in 2017 one year after the closure of the area."
This method of protection could be used as a tool in other Pacific countries.
"Throughout the Pacific, countries have been establishing those large areas on the assumption that these spillovers are going to happen and we are now confirming that in Hawaii at least it is happening. It does support the creation of these areas" Lynham said.