Ocean zoning within a sparing versus sharing framework

The land-sparing versus land-sharing debate centers around how different intensities of habitat use can be coordinated to satisfycompeting demands for biodiversity persistence and food production in agricultural landscapes. We apply the broad conceptsfrom this debate to the sea and propose it as a framework to informmarine zoning based on three possible management strategies,establishing: no-take marine reserves, regulated fishing zones, and unregulated open-access areas. We develop a general modelthat maximizes standing fish biomass, given a fixed management budget while maintaining a minimum harvest level. We findthat when management budgets are small, sea-sparing is the optimal management strategy because for all parameters tested,reserves are more cost-effective at increasing standing biomass than traditional fisheries management. For larger budgets, theoptimal strategy switches to sea-sharing because, at a certain point, further investing to grow the no-take marine reserves reducescatch below the minimum harvest constraint. Our intention is to illustrate how general rules of thumb derived from plausible,single-purpose models can help guide marine protected area policy under our novel sparing and sharing framework. This work isthe beginning of a basic theory for optimal zoning allocations and should be considered complementary to the more specificspatial planning literature for marine reserve as nations expand their marine protected area estates