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

Yellowfin and bigeye tuna catches rise outside 1.5m sq km marine protected area, proving value of no-catch zone, researchers say

Six years ago, the then US president, Barack Obama, created the world's largest fully protected ocean reserve by expanding the existing Papahnaumokukea 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%.