Marine reserves : Parks, baselines, and fishery enhancement

Coastal zones are usually managed with two main objectives: (1) conservation/maintenance of biodiversity and intrinsic ecosystem services and (2) maintenance of sustainable fisheries. The management needs that can be met with marine protected areas fall into corresponding categories. First, fully protected (that is, no-take) reserves-parks-offer benchmarks and protect ecosystem integrity while encouraging research, education, and aesthetic appreciation of nature. Second, by allowing focused local control of human impacts, marine protected areas can be used to focus more intense local management designed to increase yield and allow research to help define sustainability and protect against uncertainty by using carefully managed fisheries as a research tool. We have been gambling with the future by establishing a poor balance between short-term profit and long-term risks. The absence of meaningful, fully protected reserves has produced a situation in which there are virtually no areas north of the Antarctic in the world's oceans that have exploitable resources where scientists can study natural marine systems. In most areas the higher-order predators and many other important species have been virtually eliminated; many benthic habitats have been much changed by fishing activities. Without solid data documenting changes through time, the relative merits of various causes and effects that operate in complex ecological systems can always be argued. Without natural systems important questions cannot be studied-for example, how the ecosystem roles of various species can be assessed, how they can be managed in a sustainable manner, and how we can evaluate resilience or relative rates of recovery. Networks of fully-protected reserves could facilitate research into such questions, contribute to the recovery of many coastal systems, and enable society to enrich its existence by observing species that should be part of its heritage (Murray et al., 1999). The use of marine protected areas as fishing refugia has met strong resistance by fishers and many managers, and it is misunderstood by many conservation biologists because different proponents have different, usually simplistic, visions. It is important to spell out the objectives of each proposed example. Our essential habitat perspective emphasizes that each situation depends on specific life-history parameters and emphasizes critical thresholds in population dynamics, including density and behavior for fertilization, transport processes, settlement, survivorship, and growth to maturity. These are extremely difficult problems, and we cannot expect simplistic solutions to be effective. The only basis for optimism is that most of the seriously affected species are not yet extinct, and we still have a little time to establish permanent fully protected reserves to allow mankind to appreciate its rich but much depleted biological heritage. At least in some systems recovery can be measured over short time scales (<10 yrs), whereas others are much slower. Society as a whole is the ultimate stakeholder, not only the commercial and sports fishing industries that so dominate the public arena. Society will have to play a more active role if these species and habitats are to be saved.