Selecting marine reserve locations: Optimality versus opportunism

Location of most marine reserves has depended more on social criteria and o pportunism than on scientific study. Nevertheless, numerous studies from ma ny habitats and places around the world indicate that fully protected reser ves (areas closed to all fishing) have shown clear benefits, at least withi n their boundaries. This evidence suggests that reserves will work in most areas they are placed. Many people are uncomfortable with this haphazard ap proach and worry that we should be looking to science to help optimize plac ement. Here I examine some of the key factors affecting reserve performance and ways they might influence our approach to locating reserves. Habitat q uality, intensity of exploitation around reserves, area and proximity of ot her reserves, protected species' life history and dispersal characteristics , and boundary porosity all affect how reserves perform. Any reserve we cre ate will involve trade-offs among different objectives. For relatively sede ntary species, precise reserve placement appears relatively unimportant to performance, but for migratory species, much more precise placement will be necessary to encompass migration bottleneck and nursery areas. Two nonbiol ogical factors are of overriding importance to performance. Fully protected reserves will achieve much more than those that allow limited take, and we ll-enforced reserves will be much more effective than poorly enforced ones. Rather than seeking to optimize placement of individual reserves, we shoul d construct networks of interacting reserves as a bet-hedging strategy agai nst variability and uncertainty in the marine ecological processes, and res ource-management policies, that affect reserve performance. Opportunism, in formed by science, can achieve a great deal. The risk is much greater that we will fail to achieve our management objectives if we delay in order to e mbark upon lengthy studies than if we begin establishing reserves today on the basis of what we already know.