Larval export mitigates the cost of conservation to fisheries in over-exploited waters

In response to anthropogenic threats to marine ecosystems, governments committed to expand global Marine Protected Area (MPA) coverage to 30% by 2030 (“30✕30”). Although MPAs are perceived to result in economic losses to fisheries, they can mitigate losses through mechanisms such as larval export, which remains underrepresented in fisheries models. To assess how larval export offsets opportunity costs of MPAs, we coupled simulations of larval advection with a global bioeconomic size-spectrum model of fisheries harvest. We show that whilst larval export reduced opportunity costs, benefits depended on management outside MPAs. Under heavy overfishing, larval export increased global catches by ~40% by 2040, whereas under strong fisheries management, larval export moderated global catch losses by ~3%. Benefits were greater close to MPAs, in areas of higher productivity, and where currents were faster. These findings illustrate the importance of accounting for larval export to assess economic trade-offs associated with conservation measures.