Selecting Locations for the Reserves
Given the conservative coverage area targets, clear thought must be given to maximizing the impact of each unit of ocean area protected. We emphasize that it is not the size of individual sanctuaries that is the most important matter, but rather the global scale of coverage (Guenétte, et. al. 2003). There are several general principles that should be followed when selecting locations for marine reserves. To properly function as a buffer against external exploitation, the 10% of ocean area must include a representative sample of habitats and ecosystems should be protected (Ballantine 1991). Particular emphasis should be placed on protecting especially fragile, unique, or threatened ecosystems. Furthermore, multiple examples of each habitat type should be protected to insure against localized disturbances. Finally, individual Marine Reserves should be set up in mutually reinforcing networks to maximize their influence. Such systems rely on knowledge of the physical processes in play in a given area, especially the activity of advective and convective current systems (Johnson, Funicelli, & Bohnsack 1999 and Ballantine 1991).
When aiming to protect multiple species within a single MPA, it is necessary to consider the migratory patterns and mobility of such species. A very mobile fish population would have a faster biomass exchange rate from within the MPA to outside of it, rendering an MPA less effective than it would be for a less mobile species that was less likely to move outside of the MPA. Also MPAs must be placed along the axis of movement for populations as opposed to perpendicular. This increases the time the fish will remain within the MPA and therefore decreases the likelihood of being caught. (Watson, Alder, Walters, 2000)
Difficulties arise when trying to use MPAs to protect highly migratory species. It would be inefficient and controversial to try to place an MPA to cover the entire migration path of a population. Therefore in order to target a migratory species one possiblity is the implementation of dynamic MPAs. By tracking indicators of concentrations of the migratory fish population such as ocean fronts, the boundaries of the MPA can be changed regularly to keep up with the population. With an everchanging boundary, however, confusion as to what is or is not allowed can develop leading to problems for fishermen and those trying to regulate the MPA. (Hyrenbach, Worm, Fonteneau, Gilman, 2007)
Although the No-Take Zones in this proposal are intended to primarily target entire ecosystems, we acknowledge that there are biological or economic situations in which a certain organism is of particular importance. In such cases, an understanding of the relevant biology and ecology is critically important. For example, key life stages or migration routes of the target species can be protected by careful placement of reserves (Robichaud & Rose 2004). A land-based analogy is the protection of bird nesting sites and reserves for migratory birds, respectively. Zoning within MPAs can solve the problem of certain species within the same area requiring different levels of protection. This method has been used in existing MPAs to provide strict restrictions on those populations that are most in danger of long-term extinction. (Marine 2007) Another form of zoning regards vertical zoning. Vertical zoning allows MPAs to target species that live in a particular depth of the ocean without completely restricting fish in that area. These can be particularly useful when protecting life on the ocean floor from particular destructive methods of fishing such as trawling. (U.S. 2006)
When setting up marine reserves, it is also important to consider potential ecological barriers that will prevent the occurrence of spillover, and therefore reduce the ability of the protected area to enhance adjacent fisheries. For instance, one study in the Turks and Caicos Islands found that numerous shallow sand habitats enclosed a population of conch, reducing its spillover into nearby areas (A. Tewfik and C. Bene, 2003).
Of course, there are also the practical matters of cost and enforceability that must be factored into any setup of marine protected areas. Creating a layout for Marine reserves that optimizes these numerous biological, physical, and social factors is a complex issue. Fortunately, there exist several environmental modeling packages such as Marxan (Possingham, Ball, & Andleman 2000), ResNet, and C-Plan that use stochastic statistical methods to optimize these parameters. Naturally, these types of algorithms are only as accurate as the data put into them, so continued emphasis on the collection of scientific data is essential. (Hyperlink to EXTERNAL FURTHER RESEARCH PAGE).