A recent report by the United Nations cautions about the use of marine protected areas as a panacea for conservation efforts.
"MPAs are widely advocated and widely declared. But nearly all of them are paper parks (Mora et al 2006). They are legal, may have management staff, usually have detailed regulations governing their use, but there is little if any enforcement of regulations. The paper park syndrome exists for several reasons. Many coastal states have quite limited budgets, and adequately resourcing an environmental management department to administer MPAs simply does not happen."
"There also appears to be an over-reliance by managers on the no-take protected area concept. MPAs can manage activities that occur within their borders well, but MPAs have been particularly ineffective for managing fisheries in surrounding waters, or extrinsic disturbances such as coral bleaching, pollution, or invading species ( Jameson, et al.2002). Yet, much of the literature on protected areas is advocacy suggesting that a network of MPAs is practically all a nation needs to effectively manage its coastal waters. Of course, if numerous, well-managed, MPA networks existed, our coastal ocean would be in much better state than it is – mostly there are small, isolated, poorly managed MPAs. This management tool could be used much more effectively than at present, and with some additional research it should be possible to design networks of MPAs effectively (World Bank 2006)"
Read more of the report here...