Evidence of spillover benefits from large-scale marine protected areas to purse seine fisheries.

Global tuna fisheries are valued at more than $40 billion, with the majority of this value derived from purse seine fisheries. Recently created large-scale marine protected areas are potentially big enough to protect highly migratory species such as tuna, possibly leading to increases in abundance (a conservation benefit) and consequent spillover near protected area boundaries (an economic benefit). Using publicly available data from nine large-scale marine protected areas across the Pacific and Indian oceans, we find that catch-per-unit-effort in tuna purse seine fisheries has increased by an average of 12 to 18% near protected area boundaries, and this increase declines with distance from the boundaries. The increase is larger for bigeye tuna () than for skipjack tuna (), in line with fisheries science simulation models.