Incorporating larval dispersal into MPA design for both conservation and fisheries

Abstract

Larval dispersal by ocean currents is a critical component of systematic marine protected area (MPA) design. However, there is a lack of quantitative methods to incorporate larval dispersal in support of increasingly diverse management objectives, including local population persistence under multiple types of threats (primarily focused on larval retention within and dispersal between protected locations) and benefits to unprotected populations and fisheries (primarily focused on larval export from protected locations to fishing grounds). Here, we present a flexible MPA design approach that can reconcile multiple such potentially conflicting management objectives by balancing various associated treatments of larval dispersal information. We demonstrate our approach based on alternative dispersal patterns, combinations of threats to populations, management objectives, and two different optimization strategies (site vs. network-based). Our outcomes highlight a consistently high effectiveness in selecting priority locations that are self-replenishing, inter-connected, and/or important larval sources. We find that the opportunity to balance these three dispersal attributes flexibly can help not only to prevent meta-population collapse, but also to ensure effective fisheries recovery, with average increases in the number of recruits at fishing grounds at least two times higher than achieved by standard habitat-based or ad-hoc MPA designs. Future applications of our MPA design approach should therefore be encouraged, specifically where management tools other than MPAs are not feasible.