migratory behavior of many marine species, discussed earlier, is that even the largest reserves may fail to protect all resident species adequately (Ray, 1999). Widely dispersing or migratory species, for instance, will require networks of reserves. Site selection must take into account features at the scale of the reserve, but should also place the reserve into the larger context of the ecosystem within which it is embedded.
Ballantine (1997) proposed a series of principles for the development of regional reserve networks that build on some of the selection criteria for individual reserves. He argued that (1) all biogeographic regions and all habitats should be represented in reserves and (2) there should be replication of reserves within all regions and habitats among reserves. Ballantine also emphasized that within a network, reserves should have some level of connectivity; that is, they should be close enough for resident populations to interact through dispersal or migration. This connectivity among reserves, would be inherent in network design that fulfilled biogeographic, habitat representation, and replication criteria. In other words, fully representative networks with sufficient replication will inevitably contain reserves that are close enough together to interact effectively. Still, Ballantine (1997) offered little guidance as to how to weigh other criteria for selecting reserve sites.
Managers of marine resources would prefer an evaluation process that is more objective. Arbitrary choice of reserve sites could allow vulnerable areas to be degraded or destroyed, while other, more resilient habitats or species are protected. For instance, if criteria are clearly defined and agreed on prior to reserve selection, selected sites can be more easily justified. Much of the opposition that blocked zoning plans for the Florida Keys National Marine Sanctuary hinged on arguments that the locations of zones had not been chosen objectively. One of the original ecological reserve sites proposed, the Dry Tortugas, incorporated an area that satisfied neither conservationists nor fishers. Conservationists argued that it contained too little coral reef, while fishers objected to the extent of shrimp fishing ground that would be lost to them (Ogden, 1997). As a consequence, the siting of the Dry Tortugas reserve was deferred, and a more participatory design process was employed in planning the current site.
The development of more objective approaches could help meet the needs of managers for a more transparent process (Hockey and Branch, 1997; Roberts et al., in review a, b). The COMPARE (Criteria and Objectives for Marine Protected Area Evaluation) procedure described by Hockey and Branch (1997) marries the objectives of reserves to the selection criteria employed. COMPARE specifies 14 different objectives for reserves that are distributed among three categories: fishery management, biodiversity protection, and human use (Table 6-2). The authors propose 17 biological and social criteria that can be used selectively (not all are relevant to all objectives) to determine the value of a candidate site in meeting desired objectives. Sites are scored against each of the criteria, allowing straightforward judgments to be made of their relative value.