World’s largest ocean reserve off Hawaii has spillover benefits nearby, study finds

Hawaiian dascyllus and other reef fish swimming in the protected waters of the Papahānaumokuākea marine national monument. Photograph: Karen Bryan/NOAA

Six years ago, the then US president, Barack Obama, created the world’s largest fully protected ocean reserve by expanding the existing Papahānaumokuākea marine national monument in Hawaii, a world heritage site that include islands, atolls and archeological treasures. Now scientists have found that the reserve, which spans 1.5m sq km (580,000 sq miles) and is inhabited by whales and turtles, has brought unexpected benefits to the surrounding ocean.

Catches of yellowfin tuna, known as ahi in Hawaiian, were found to have risen by 54% between 2016 and 2019 near the reserve, within which fishing is banned, while catches of bigeye tuna rose by 12%.