Spillover benefits observed from world's largest marine protected area, Papahānaumokuākea Marine National Monument

Fisheries data reveals spillover benefits from the world's largest fully protected marine protected area (MPA), Papahānaumokuākea Marine National Monument, researchers report. The new study provides evidence that the protections of these regions also expand outside their borders and positively affect migratory species like bigeye and yellowfin tuna. Although MPAs have repeatedly been shown to protect local populations of fish, previous research has cast doubt on their potential to provide refuge and fishery spillover benefits for migratory species, like tuna or swordfish, as many MPAs are small compared to the geographic range of these species. However, identifying any potential spillover benefits has been a challenge. Ocean ecosystems are complex and sometimes require time to recover before spillover effects can occur. Also, creating MPAs often leads to changes in human behavior that can mask or exaggerate spillover effects. Here, Sarah Medoff and colleagues evaluated whether spillover fishery benefits have accrued from the Papahānaumokuākea Marine National Monument – a more than 1.5 million-square-kilometer fully protected MPA in Hawaii. Medoff et al. evaluated species-specific catch-rate data for individual fishing vessels operating near to, and far from, the MPA before and after its most recent expansion in 2016. Their analysis provided clear evidence that the protections afforded to two migratory species that pass through the MPA – yellowfin tuna and bigeye tuna – led to spillover effects outside of Papahānaumokuākea's borders which were previously seen only for resident fish populations.