Hawaiian Marine Protected Areas Produce Spillover

by Katie Huang

Marine protected areas (MPAs) can be beneficial to fisheries through spillover effects, which occur when protected fish stocks recover and migrate into open areas. As a result, fishers tend to react by increasing fishing pressure near MPA boundaries to capitalize on these biomass gradients. To supplement previous research on spillover, Stamoulis and Friedlander (2013) studied a Hawaiian MPA with a new seascape approach that incorporated habitat variables, multiple scales of study, and information on fishing pressure. They took visual surveys of fish populations both targeted and not targeted for conservation along random transects and determined their biomass, species abundance, and density in protected and open areas. The authors found that all fish wellbeing measures were observed to be significantly higher inside the reserve. Also, as distance increased from the MPA boundaries, biomass decreased for resource fish but remained constant for non-resource fish, indicating the existence of a spillover gradient. Although fishing was more concentrated near MPA borders, current harvest rates are sustainable for the time being. The authors suggest that similar comprehensive studies be made throughout Hawaii but that further research should also include analysis on larval and egg export, a second benefit to fisheries besides spillover. Continue reading