Page 97

6

Design

Image: jpg
~ enlarge ~

As with any enterprise, good design is fundamental for the success of marine protected areas (MPAs). This chapter evaluates how existing knowledge of marine ecosystems can be applied to the design of marine reserves and protected areas. Three important questions are covered: (1) How should the location of MPAs be chosen? (2) How large should MPAs be? (3) What kinds of zoning are useful in MPAs?

HOW SHOULD THE LOCATION OF MARINE PROTECTED AREAS AND RESERVES BE CHOSEN?

One of the more controversial issues in designing MPAs is deciding where to put them. While it may be possible to achieve consensus on the need for MPAs and agreement in principle on their size and the entities that should be protected, when it comes to choosing discrete sites, hostilities often break out. Frequently, it is the social aspects of locating reserves within MPAs that dominate arguments. For example, residents of an exclusive development hotly contested plans to include an ecological reserve adjacent to Key Largo in the newly created Florida Keys National Marine Sanctuary (U.S. DOC, 1994). They feared the reserve would prevent them from recreational fishing, or even landing fish, close to their homes. Commercial fishers responded similarly, suggesting that reserves would exclude them from their favored fishing spots. Clearly, social acceptance of the MPA plan, especially the location of reserves, is critical to



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 97
Page 97 6 Design ~ enlarge ~ As with any enterprise, good design is fundamental for the success of marine protected areas (MPAs). This chapter evaluates how existing knowledge of marine ecosystems can be applied to the design of marine reserves and protected areas. Three important questions are covered: (1) How should the location of MPAs be chosen? (2) How large should MPAs be? (3) What kinds of zoning are useful in MPAs? HOW SHOULD THE LOCATION OF MARINE PROTECTED AREAS AND RESERVES BE CHOSEN? One of the more controversial issues in designing MPAs is deciding where to put them. While it may be possible to achieve consensus on the need for MPAs and agreement in principle on their size and the entities that should be protected, when it comes to choosing discrete sites, hostilities often break out. Frequently, it is the social aspects of locating reserves within MPAs that dominate arguments. For example, residents of an exclusive development hotly contested plans to include an ecological reserve adjacent to Key Largo in the newly created Florida Keys National Marine Sanctuary (U.S. DOC, 1994). They feared the reserve would prevent them from recreational fishing, or even landing fish, close to their homes. Commercial fishers responded similarly, suggesting that reserves would exclude them from their favored fishing spots. Clearly, social acceptance of the MPA plan, especially the location of reserves, is critical to

OCR for page 97
Page 98 TABLE 6-1 Summary of Social and Economic Criteria Used to Select Marine Protected Area and Reserve Locations Value Type Criteria Economic Number of fishers dependent on the area Value for tourism Potential contribution of protection to enhance or maintain economic value Social Ease of access Maintenance of traditional fishing methods Presence of cultural artifacts or wrecks Heritage value Recreational value Educational value Aesthetic appeal Scientific Amount of previous scientific work Regularity of survey or monitoring work Presence of current research project Educational value Feasibility or Practicality Social and political acceptability Accessibility for education and tourism Compatibility with existing uses Ease of management Enforceability SOURCE: Adapted from Roberts et al, in review b. successful implementation (see Chapter 4), but a balance between social concerns and biological function must be achieved. What methods are available for selecting functional reserves that meet these social and ecological criteria? Kelleher (1999), building on previous work of the International Union for the Conservation of Nature and Natural Resources (IUCN, now the World Conservation Union), provided broad guidelines for selecting MPA sites, drawn from experience in the selection of terrestrial protected areas. He identified several classes of related criteria that bear on choice of a site: biogeographic and ecological criteria; naturalness; economic, social, and scientific importance; international or national significance; practicality or feasibility; and duality or replication. However, these guidelines neither offer guidance on how to prioritize these criteria nor provide advice on how to rank candidate sites according to each criterion. This approach has been elaborated in recent papers (e.g., Salm and Price, 1995; Nilsson, 1998; Agardy, 1997). A summary of these criteria is provided in Table 6-1. All of these efforts focus on the problem of selecting individual marine reserves, but there is a growing awareness that this piecemeal approach to reserve establishment ultimately may fail to protect species and functional ecosystems. The implication derived from the broad dispersal capabilities and

OCR for page 97
Page 99migratory 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.

OCR for page 97
Page 100 TABLE 6-2 Example of the COMPARE Procedure as Applied to Cape Point Nature Reserve in South Africa Objectives Criteria Biogeography Habitat Diversity Rare or endemic species Vulnerable Stages (all species) Reduced Fishing Mortality Vulnerable Stages (exploited species) Adjacent Yield Spawner Biomass Research Monitoring Ecotourism Law-Impact Recreation Education Exploitation Totals for Criteria Percentages Regionally representative 1 2 1 1 2 7 70 Not conserved elsewhere 1 0 0 0 1 13 High habitat diversity 1 1 1 1 1 5 50 Includes fragile habitats 2 2 1 2 7 88 Houses vulnerable species 1 1 1 1 1 5 50 Protects rare or vulnerable stages 1 1 1 1 1 1 1 4 50 Pristine or restorable 2 2 2 2 2 10 100 Special natural features 0 0 0 1 1 13 Supports exploited species 1 1 1 1 2 2 2 2 12 75 Supplies adjacent areas 1 1 2 50 Large enough 1 1 1 1 0 1 1 1 2 2 1 2 2 1 17 61 Adjacent terrestrial reserve 1 1 1 2 2 2 2 1 2 14 78 Aesthetically appealing 2 2 2 2 8 100 Accessible to people 2 2 2 2 2 2 12 100 Effective management 2 2 2 2 1 2 2 2 2 2 1 2 2 2 26 93 Satisfies social needs 1 2 1 4 67 Preserves historical sites 0 0 1 1 17 Totals for objectives 5 11 6 5 4 8 5 4 19 16 13 10 23 7 136 Percentages 50 79 50 63 50 57 63 50 73 80 54 100 82 88 69 Overall totals 27 21 88 136 Overall percentages 61 55 76 69 SOURCE: Hockey and Branch, 1997. NOTES: 0 = ineffective; 1 = moderately effective; 2 = highly effective. Blank cells are inapplicable combinations. In this example, the reserve scores 61% for protection of biota, 55% for its contribution to fishery management, and 76% for provision of human uses, or 69% overall. This procedure has been applied to all of the existing reserves in South Africa and has helped evaluate the extent to which they are able to meet their objectives. It has also been valuable in determining what additional MPAs are needed to complete the country's national network.

OCR for page 97
Page 101

OCR for page 97
Page 102 Table 6-2 illustrates an example application of the procedure to an existing marine reserve in South Africa. The COMPARE approach offers some welcome advantages over ad hoc site selection. It requires that sufficient and comparable data be collected for candidate sites. The simple, semi-quantitative evaluation method neatly summarizes the pros and cons of different sites and helps to pinpoint the deciding factors for making choices. The authors also suggest that management plans for reserves chosen using this approach can be guided by the objectives articulated during selection. It also goes beyond previous schemes in that the process can be used to build regionally representative networks of reserves. It is limited, however, because Hockey and Branch (1997) give only brief guidance on how to score sites according to each criterion. Another approach that builds upon Hockey and Branch's (1997) efforts includes an evaluation scheme that aims to meld site selection more intimately with network development (Roberts et al., in review a, b). This approach departs from the COMPARE method, however, in that the criteria either are exclusively biological or are dependent on underlying biology. Their rationale is that if social and economic criteria override biological criteria, places of little biological value could be protected at the expense of areas with greater ecological value. The competing needs for biological relevance and social acceptance may be resolved by involving the stakeholder community at the outset in the process of identifying goals for the MPA and reviewing the criteria and data for site selection. Socioeconomic analysis of candidate sites is needed to identify and rule out areas that would be unacceptable to the community and, hence, impossible to implement or enforce. Biogeographic and habitat representations are at the heart of most schemes for site selection. Leslie et al. (in review) used these criteria to design potential networks of fully protected reserves for the Florida Keys National Marine Sanctuary. They used computer-based selection algorithms to choose network designs that represented all habitats according to their relative coverage in the region. This exercise revealed that there are literally thousands of biologically adequate network designs. Selection from among these designs can be narrowed by identifying those network(s) with the lowest negative impacts on the surrounding communities. In these examples, as well as other attempts to develop an objective approach to site selection, it is clear that the most subjective issue is the weighting of criteria. This reflects the reality that there is no formula that can be applied across the diversity of situations for planning MPAs. Therefore, involving stake-holders in every step of the process, from providing their knowledge of the environment and its resources, to making decisions about how to score sites relative to each criterion, is the most effective way to develop a cooperative, informed, MPA management plan. If conservation of biodiversity is the goal, then ecological reserves must be

OCR for page 97
Page 103located in places that will offer protection to the full spectrum of species and habitats. Box 6-1 lists one example of evaluation criteria, and Box 6-2 explains how these criteria could be applied. Biogeographic regions are usually defined on the basis of species composition and, in the marine realm, are often related to hydrographic features. Examples include currents (Emanuel et al., 1992), gradients of water quality (Roberts, 1991), patterns of productivity (Longhurst, 1998), and a complex mix of historical processes. These types of features have been used by Parks Canada for identifying representative marine areas in the development of Canada's National Marine Conservation Areas System. The Parks Canada criteria include geologic features (such as cliffs, beaches, and islands on the coast, and shoals, basins, troughs, and shelves on the seabed); marine features (tides, ice, water masses, currents, salinity, freshwater influences); marine and coastal habitats (wetlands, tidal flats, estuaries, high-current areas, protected areas, inshore and offshore areas, shallow water, and deep water areas); biology (plants, plankton, invertebrates, fish, seabirds, and marine mammals); and archaeological and historic features.1 Within biogeographic regions, candidate sites can be ranked on the basis of species richness or complementarity analyses used to ensure representation of species present (e.g., Roberts et al., in review b; Turpie et al., 2000). However, few sites have detailed data on species composition. In this case, habitats can be used as a convenient proxy for species. Ward et al. (1999) estimate that 93% of taxa will be represented in reserves that cover ≥40% of each habitat type. This is not to say that the presence of species of particular concern should not play a role in site choice. These species can be accounted for in the application of modifying criteria. When habitat representation is the priority, sites that have a high level of habitat diversity will receive a higher ranking. In setting the goals for an MPA, the following questions should be addressed: Should different habitats be afforded different priority for protection? Are some more or less valuable or vulnerable? Should a greater proportion of some habitats and less of others (i.e., 5% of sandy shores and 30% of coral reefs) be protected? One approach is to protect habitats in proportion to their regional coverage (Ballantine, 1997; Roberts et al., in review a). Thus, if seagrass beds cover 25% of the total region, they would cover roughly 25% of the total area of reserves established. This does not mean that individual reserves would contain 1 http://parkscanada.pch.gc.ca/nmca/nmca/program.htm.

OCR for page 97
Page 104 BOX 6-1 Criteria for Selection of Ecological Reserve Sites and Development of Networks (Roberts et al., in review a) All of the criteria have a biological basis or strongly affect species and habitats in candidate reserves. Biogeographic representation. All biogeographic regions should be represented and reserves should be replicated in each. Habitat representation and heterogeneity. All habitats should be represented and replicate habitats protected in different reserves within biogeographic regions. Level of human threat. Very high levels of human threat will exclude a site from consideration, but threats that can be mitigated could increase priority for protection. Level of threat from natural catastrophes. Sites that are foci for extreme natural disturbances should be avoided. Size of site. Candidate sites should be large enough to support viable habitats. Connectivity. Sites should interconnect with others through dispersal and migration. Presence of vulnerable habitats. Vulnerable habitats have higher priority for protection. Presence of vulnerable life-history stages. Vulnerable life-history stages, such as spawning sites, are afforded higher priority. Presence of exploitable species. Sites must be capable of supporting exploited species, even though the populations may be at very low levels at the time of implementation due to overfishing. Presence of species or populations of special interest. Endemic, relict, or globally rare species, for example, increase the value of a site, as would populations that are genetically distinct. Ecosystem functioning and/linkages. Areas that link with and support other systems have a greater value than those that do not; similarly, sites that depend on links with other systems are vulnerable unless these places are also protected. Provision of ecological services for people. Services such as coastal protection or water purification add value to a site. equivalent proportions of each habitat. Some reserves might consist entirely of one habitat, whereas others would contain a variety. Proportional coverage is the simplest argument to make, but there are other possible approaches. The answers depend on the needs of each region, but connectivity among reserves will likely require greater proportional protection of rare than of common habitats (Roberts et al., in review a). In some cases, the primary objective for establishing an MPA may be to reduce or exclude pollution or mining. One of the main purposes of designating

OCR for page 97
Page 105 the Great Barrier Reef Marine Park in Australia was to exclude oil drilling and coral mining (Kelleher and Kenchington, 1982). Similarly, a primary motivation for establishing some of the National Marine Sanctuaries, such as the sanctuary in Monterey Bay, was the exclusion of oil and gas exploitation. Potential sites may be scored against a series of six modifying criteria that affect their value as candidates for MPAs and reserves. Not all of these criteria are applicable to all objectives for MPA sites, but each is important for the development of successful networks of marine reserves: 1. Supplement or supplant conventional management of exploited species. 2. Protect rare species or vulnerable habitats. Vulnerable habitats generally include a biological component that is sensitive to disturbance and may take many years to regenerate. 3. Safeguard critical life-history stages, for example, spawning aggregation sites or juvenile nursery grounds (see Chapter 5). 4. Secure linkages among interdependent habitats. For example, communities present on rocky shores may derive their sustenance from adjacent kelp forests (Bustamante et al., 1995), and mangroves may protect offshore reefs from sediment carried by terrestrial runoff (Duke et al., 1997). 5. Maintain an ecosystem service such as the water filtration function performed by suspension-feeding invertebrates in bays and estuaries. 6. Provide connectivity among reserves for persistence of species or between reserves and unprotected areas for repopulation of exploited populations. The application of these criteria depends on the goals of the MPA and zones designated as reserves. For example, the design of MPAs to improve fishery management may emphasize criteria 1, 3, and 6. Designing MPAs for conservation of biodiversity may emphasize criteria 2, 4, and 6. It is logistically difficult to conduct experiments to evaluate connectivity. Roberts (1997a) suggested using prevailing current patterns to map connections among areas. However, others point out that currents may not reveal the true linkages if species actively control their pelagic dispersal (Swearer et al., 1999; Warner et al., 2000; Barber et al., in press). Biogeographic patterns of distribution provide a boundary within which connectivity may be evaluated. These boundaries may not depend on current patterns. For example, Barber et al. (in press) found that present-day current patterns could not explain patterns of genetic similarity among populations of mantis shrimps on Indonesian coral reefs. Generally, connectivity will be achieved automatically when networks of reserves are designed according to the other criteria, as found when these criteria were used to propose sites for marine reserves in Europe (Halfpenny and Roberts, in review). However, any obvious gaps should be avoided. The schemes developed by Hockey and Branch (1997) and Roberts et al. (in review b), although applicable to the problems of reserve selection and network-

OCR for page 97
Page 106 BOX 6-2 Decision Process for Developing Reserve Networks (Roberts et al., in review b) 1. Define the goals of the network. 2. Define area of interest. 3. Divide it into possible reserve units—these may be defined in many ways, for example through grids of uniform-sized blocks (e.g., 10 km2), stretches of coastline, habitat classification schemes, or other means. 4. Select criteria for the evaluation of units that are appropriate to the goals. 5. Decide how to quantify the information needed to determine the level achieved for each criterion. 6. Assemble information on these units (e.g., species or habitats present, levels of threat). 7. Evaluation process: a. Characterize or score sites based on the following characteristics: Define biogeographic regions and then score sites based on what region they occur in. At this stage, sites could be stratified according to region and site selection decisions made separately for each region. The latter approach would be most useful where a large geographic area is being considered and there are many potential sites from which to choose. Define habitats within each biogeographic region for representation. Exclude sites that are subject to excessive levels of threat from human or natural sources. Include sites that are already reserves. Score potential reserves on the basis of habitat heterogeneity and representation criteria, ensuring that reserve units will be sufficiently large to include viable populations. Rank or score sites within each habitat type according to other modifying criteria. b. Set conservation targets for each of the criteria above (e.g., decide what proportion of the region and of each habitat to protect, what level of replication is required, levels of connectivity desired). c. Select among sites for inclusion in the network (this can be done with an algorithm or by a ranking or scoring method). Criteria may be given different weights at this stage in order to meet specific network objectives. Map the different biologically adequate networks of reserves that are possible. d. Ensure that alternative reserve networks resulting from the above selection process are sufficiently connected. 8. Use information on alternative, biologically adequate, reserve networks to inform final network selection according to socioeconomic criteria. ing, may also be used to choose boundaries of individual MPAs or to designate zones for reserves within MPAs. Lafferty et al. (in review) show how these criteria can be applied to the problem of placing no-take zones in the Channel Islands National Marine Sanctuary in California.

OCR for page 97
Page 107 The Importance of Developing Multifunctional MPAs and Reserve Networks The fragmentation of objectives among different management entities often leads to a proliferation of uncoordinated zoning measures. McArdle's (1997) review of the 104 California MPAs, for instance, shows how the uncoordinated designation of sites results from overlapping, competing, and sometimes conflicting agendas of the different management agencies. This leads to a morass of legislation that perplexes users and may in the end harm, rather than help, conservation by giving the illusion of protection where little exists. For example, only 4 small MPAs, of the 104 in California, prohibit all recreational and commercial fishing. Agencies need to cooperate in the establishment of MPA networks in order to reduce the costs of planning, implementation, and enforcement. Furthermore, implementation of a coordinated network of MPAs, using a selection scheme such as the ones described here, will ensure the greatest conservation benefit per unit area protected. The executive order issued by President Clinton on May 26, 2000, recognizes this need and directs the National Oceanic and Atmospheric Administration (NOAA), in cooperation with the Department of the Interior, “to establish a Marine Protected Area Center...to develop a framework for a national system of MPAs.” Biodiversity conservation, fishery production, and the full suite of ecosystem services depend on maintaining ecosystem integrity. This is a central objective for the creation of representative systems and fully interconnected networks (Agardy, 1997; Roberts et al., in review a, b). Fragmented initiatives are much less likely to safeguard ecosystem processes. If reserves are to enhance fisheries through spillover of juveniles and adults, they must have “leaky” edges. As already discussed, larger reserves will have lower relative rates of export across their boundaries than small ones because the edges form smaller proportions of the area. For species that associate closely with particular habitats, reserve boundaries will be more porous (and spillover greater) if they are placed across areas of continuous habitat (Roberts, in press). Reserves whose boundaries are contiguous with habitat discontinuities will tend to have lower rates of spillover. However, reserves in which export rates are too high will fail on both fishery and conservation grounds. A balance between retention and spillover can be achieved at the reserve and network scales by incorporating a mix of boundary conditions. As described in Chapter 5, sources are locations that supply recruits to other places, whereas sinks are places supported by recruitment from elsewhere without contributing to other areas (Pulliam, 1988). Crowder et al. (2000) modeled a system of sources and sinks for reef fish and found that at high fishing effort, placement of reserves in sink areas not only reduced the capacity of the reserve to support the fished population, but also concentrated fishing on source popula-

OCR for page 97
Page 115 ~ enlarge ~ FIGURE 6-2 Hypothetical population densities of a marine invertebrate species along an imaginary stretch of coastline with two fully protected reserves. Due to Allee effects at reproduction, the species can reproduce successfully only above a certain threshold of population density, shown as the checked area on the figure. In this circumstance, such densities are reached only inside reserves. Although the species exists outside reserves, only the reserve populations contribute to recruitment. Although fishery management issues provide much of the justification for reserves, some recent studies have examined more general conservation arguments. Almost all discussions of the design of systems of reserves emphasize the importance of preserving the same species and habitats through replication in several different reserve sites. Several studies that have evaluated how much area needs to be protected to achieve representation and replication conclude that areas in the range of 10% to 35% are appropriate (Table 6-3). Broad species conservation may also require interconnected reserve networks. Interreserve distance provides a measure of connectivity (or the likelihood of interaction among populations in different reserves). Species that depend on other populations for recruitment will require networks of reserves that have high connectivity. Connectivity is also critical for persistence of species that are functionally extinct in areas outside reserves, for instance, when an Allee effect demands high population density for reproductive success (Figure 6-2). To extending this argument; if management outside the reserve is poor, the level of human impact

OCR for page 97
Page 116will be greater, and larger protected areas will be needed. Most fishery models and a metapopulation model (Man et al., 1995) show that larger closures are needed to maintain populations if no additional management measures are applied outside the reserves. Beyond predicting that more reserve area will be needed as human impacts increase, we still have no clear guidance as to how the proportion of sea requiring protection will change as the intensity of impact outside reserves increases. It is probable that different habitats will require different levels of protection. To represent and replicate habitats adequately in a reserve system designed for conserving biodiversity, reserves covering more than 10% of the seas are likely to be required. However, providing insurance against overfishing and protecting nursery areas, spawning aggregation sites, or migration bottlenecks may require reserves covering a larger fraction of a given region. This review underscores the arbitrary nature of the 20% target figure. Few studies to date have assumed any protection outside reserves. Modeling studies suggest that less area would have to be protected as management outside reserves improves. Even with excellent management of nonreserve areas, a reserve system covering around 10% of the area would improve the conservation of ecological communities, provide insurance against uncertainty, and allow monitoring of natural versus human impacts. With less effective management outside reserves, 20% or more may be needed to achieve conservation goals. In any case, the particular characteristics of the habitat, the exploited species, and the management regime will affect how much area is needed to meet management goals. Optimally, areas targeted for full protection (i.e., ecological reserves) will reside within MPAs to provide a buffer zone that enhances the conservation benefits of the reserve. These MPAs could cover a much larger proportion of the region—for example, the Florida Keys National Marine Sanctuary (FKNMS)—while affording full protection only within specified zones. How Large Should Individual Reserves Be? To date, much of the evidence on reserve effects has come from small and isolated reserves that are closed to fishing (consisting primarily of artisanal fishers) in the Philippines (Alcala, 1988; Russ and Alcala, 1996) and even a tiny reserve encompassing only 2.6 hectares of coral reef in St. Lucia (Roberts and Hawkins, 1997). The increases observed in species abundance and biomass indicate, first, that fishing has a measurable impact on marine ecosystems and, second that reserves can be used to facilitate recovery of depleted fish stocks. Although in St. Lucia, even some mobile species benefited from the reserve, species that range widely are likely to gain less from small than from large reserves. Halpern (in review) analyzed data from studies of 76 reserves that were closed to at least some forms of fishing and looked at the magnitude of effects in

OCR for page 97
Page 117relation to reserve size. He found that overall effects (combined across all taxa in each study) on abundance, biomass, body size, or species richness were similar in large and small reserves. Although these findings provide support for using small reserves as a management tool, small reserves will not necessarily meet all management needs. Modeling studies predict that protection of mobile species will increase with increasing reserve size. Also, most of the studies in this review did not evaluate the contribution of the reserves to the populations in the surrounding areas. Since many reserves are established to enhance fishery yields, this is an important criterion for evaluating the effect of size on reserve function. The size of an individual reserve must be balanced against the mobility of the primary species requiring protection and the need for conservation versus enhancement of the fishery. Relative exchange rates will decrease as the size of the reserve increases (Kramer and Chapman, 1999), and for this reason, conservation goals will be better served by large reserves. However, if fisheries are to benefit from spillover of adults and juveniles, there must be net emigration out of reserves. Therefore, fisheries for species with low to moderate dispersal potential will be better served by smaller reserves spaced out across a management area. To meet multiple conservation objectives, networks must incorporate reserves of a variety of sizes. To be successful, reserves should be large enough to support the persistence (continued existence) of the species within. Modeling results for reserves of different sizes and species with different dispersal characteristics indicate that persistence is generally ensured if reserve breadth exceeds the dispersal distance of resident species by 1.5 times (Hastings and Botsford, 1999). Hence, a larger reserve is more likely to support the persistence of a greater number of species. The persistence of long-distance dispersers in reserves may depend on recruitment from elsewhere, either from other reserves or from unprotected areas. The availability of recruits will increase with the size of the regional population. Therefore, recruitment will depend on the regional distribution of suitable habitat, the level of exploitation outside reserves, and the amount of habitat within the reserves (Roberts, in press). Consequently, smaller reserves may be effective when the exploitation of species outside the reserves is well managed or when the proportion of protected area increases (Roberts et al., in review a). Beyond these general predictions, there are no hard-and-fast rules about how large a reserve must be for persistence. The viability of marine reserves depends on more than biology. It requires adequate enforcement and compliance—greater acceptance of small areas generally translates into higher compliance. If levels of compliance and enforcement decrease as reserves become larger, the effects of increasing size on ecological recovery may be obscured. Hence, the conclusion that size does not influence the magnitude of response (e.g., Halpern, in review) in the protected populations could be misleading.

OCR for page 97
Page 118 The relationship between the acceptance and ease of enforcement of reserves will depend on the location. Ballantine (1997) notes that acceptability is lower when current use of potential protected areas is intense. He suggests that reserves should be smaller when they are close to coasts than when they are farther offshore. Furthermore, although small reserves may be easier to enforce where it is easy to identify their boundaries and there are many people to watch them, they will be almost impossible to enforce where boundaries are hard to distinguish and patrols are intermittent. Thus, small reserves will be enforceable near coasts but not farther offshore, whereas large reserves will be less acceptable nearshore but may an be implemented and enforced offshore. MULTIPLE-USE ZONING OF MARINE PROTECTED AREAS The primary focus of the first section of this chapter has been fully protected reserves, but the intensity and extent of our activities in the ocean are likely to require broader management approaches that offer different levels of protection. For example, as currently conceived, the National Marine Sanctuary Program has a mandate to ensure harmonious use of resources within its sanctuaries. Under this mandate, it is unlikely to be either feasible or desirable for all of the area within sanctuaries to be fully protected. Nevertheless, larger-scale MPAs, such as the FKNMS, play a critical role in coordinating management. To accommodate the spectrum of different uses in larger MPAs, zoning plans are required. Zoning plans will be needed for all but the smallest MPAs because they avoid unnecessary restrictions and facilitate cooperation between managers and users. The principal objectives of a zoning plan are usually (Kelleher and Kenchington, 1992) to ensure the conservation of the MPA in perpetuity; to provide protection for critical or representative habitats, ecosystems, and ecological processes; to separate conflicting human activities; to protect the natural and/or cultural qualities of the MPA while allowing a spectrum of reasonable human uses; to reserve suitable areas for particular human uses, while minimizing the effects of these uses on the MPA; and to preserve some areas of the MPA in their natural state undisturbed by humans except for the purposes of scientific research or education. What Types of Zoning Are Useful in MPAs? Fully protected reserves within larger MPAs help underpin their biological function and ensure that resources are adequately protected. They are especially

OCR for page 97
Page 119useful in giving a high level of protection to core areas, such as sensitive habitats or sites important to vulnerable species. For the reasons given earlier, fully protected ecological reserves should often be permanent features of MPAs. Their conservation and fishery benefits will be greatly diminished if protection is only temporary. Although the placement may have to be adjusted, in concept, ecological reserves should be established with the expectation of permanence. In addition to these fully-protected reserves, zoning plans can be used to separate incompatible activities and provide spatially defined management areas that help protect ecosystem attributes while allowing compatible uses. The focus of marine management in the United States has historically been on commercial and recreational fishing. The interests of fishers have dominated discussions of how to manage the sea; hence, zoning issues often center on fishery regulations. Certainly, conventional fishery management tools, such as seasonal closures or bans on the use of certain kinds of fishing gear, offer useful tools for zoning. The scope of zoning decisions is becoming broader as other groups have demanded representation of their interest in experiencing pristine marine environments. Among them, the most active are conservation groups, but others are growing in voice and include scuba diving groups, animal rights groups, and scientists. Ecological reserves will secure some objectives of these groups but cannot satisfy all conservation goals. Hence, zones could be created that allow catch-and-release fishing, or that are protected from disturbance by particular types of fishing gear. Zoning to manage compatible and incompatible uses within a large MPA allows for resolution of conflicts between conservation goals and marine resource users, and represents an important tool for meeting the broader goals of coastal zone management (Figure 6-3). Zoning can be useful as an experimental tool, especially as a component of adaptive management. It can be difficult to determine the relative effects of fishing, environmental degradation, and other human perturbations without large-scale, long-term empirical studies in areas where the suspect activity or most activities have been curtailed. User groups often argue that their activities are not harmful and should not be restricted within MPAs. Recreational users argue that catch-and-release fisheries and diving-related tourism are nonconsumptive and should be allowed to continue in a fully protected area. Yet damage to ecosystems may occur from such activities, and opposition may arise if some users believe that the MPA is being designed to reallocate rather than conserve resources. For example, commercial fishers may argue that their access is being restricted to benefit the recreational fishing industry. By utilizing different sets of restrictions for different areas, experimental zoning schemes can help determine the impacts of different activities and avoid potential conflicts over allocation. Fishers in Australia and off southeast Alaska have argued for a vertical (i.e., depth-specific) zoning scheme in reserves designated to protect features such as seamounts and pinnacles. For instance, an area closed to bottom trawling might

OCR for page 97
Page 120 ~ enlarge ~ FIGURE 6-3 Schematic diagram indicating how different levels of protection can be applied to zones within a large MPA or used to designate a smaller area (also considered an MPA) to achieve a specific goal. Definitions of MPA, ecological reserve, and fishery reserve are presented in Chapter 1. NOTE: EEZ = exclusive economic zone. still allow commercial surface gear such as hook-and-line operations or trolling gear to be used. The Australian seamounts, rising 1,000 to 2,000 m above the seabed, harbor distinct species assemblages found nowhere else in the world. Similarly, two unusually diverse pinnacles off Cape Edgecumbe in southeast Alaska, rising 100 m off the seabed, provide refuge for social aggregations of juvenile rockfish and nesting male lingcod. In each case, the proposed closure prohibits bottom fishing and boat anchoring, thus providing refuges for groundfish and preventing damage to habitat, but allowing surface or mid-water fisheries to continue. Fishers argue that the overlying assemblages are not directly associated with the seamounts or pinnacles and could still support viable recreational and commercial fisheries. Thus, they argue for vertical zoning to allow midslope pelagic fishing. However, it will be important to determine if there are linkages between benthic and pelagic species to ensure that exploitation of surface or midwater fisheries does not harm benthic communities and undermine protection of the reserve.

OCR for page 97
Page 121 Part of the problem in vertical zoning is enforcement—it is more difficult to monitor vessels for compliance in a reserve that allows a pelagic fishery than to monitor when fishing vessels are excluded. In the Oculina reserve off Florida, there is evidence that some fishers use modified trolling gear to fish illegally on the bottom (C. Koenig, Florida State University, personal communication, 1999). In such cases, a total closure would be easier to enforce. Zoning Plans Zoning plans should consider local use patterns, expectations, attitudes, and knowledge of users with planning undertaken by people closely acquainted with local conditions. Thus, it is not reasonable to expect development of a “one-size-fits-all” model. The format of a zoning plan will vary depending on its legislative basis and local conditions. It may range from a small-scale, locally adopted, municipal plan such as those developed in the Philippines by Alcala and White (1984), to a nationally endorsed legal instrument as required under Australia's Great Barrier Reef Marine Park Act. Whatever the format, most plans will include the following elements: statement of the goals and objectives for the planned area as a whole; definition of the area with a formal statement of the boundaries of the planned area, a geographic description of its setting and accessibility, and a description of the resources of the area; description of activities in the area, concentrating on present uses but in the context of past types and levels of use in the absence of a plan—the description should include social and economic analyses; description of the existing legal and management framework applying to coastal fisheries, marine transportation, and other present uses of the area; where they still exist or can be recalled, traditional practices of management, ownership, or rights to the use of marine resources should be described; analysis of constraints and opportunities for activities possible within the area; statement of the principal threats to the conservation and management of the area; statement of policies, plans, actions, interagency agreements, and responsibilities of individual agencies existing or necessary for conservation and management of the area that is to meet the objectives of the MPA and to deal with threats and conflicts—this may usefully include a summary of consultative processes followed in plan development; statement of the boundaries, objectives, and conditions of use and entry for the component zones of the planned area; provision for regulations required to achieve and implement boundaries and conditions of use and entry; and

OCR for page 97
Page 122 an assessment of the arrangements, including financial, human, and physical resources, required to implement the zones and manage them effectively. The Planning Program After an area has been chosen as a potential site for an MPA, there are five desirable stages in the development of a zoning plan (Kelleher, 1999): 1. Initial information gathering and preparation. The planning agency, prepares a review of information on the nature and use of the area, including participation by various user groups, and develops materials for public distribution. 2. Identification of zoning needs. This involves public comment on the accuracy and adequacy of review materials and discussion of the types of zoning that should be included in the plan. 3. Preparation of draft plan. This plan defines specific objectives for each zone and identifies potential sites for these zones. 4. Publication and review of draft plan. Public comments are gathered and used to revise the draft plan. 5. Plan finalization. The government or agency adopts a revised plan that represents the best fit for meeting conservation needs and concerns of the general public and user communities. The importance of public participation in planning cannot be overemphasized. Although public participation increases the expense and time involved in planning, it can save both time and expense in the long run by increasing the likelihood that the plan will be approved, implemented, and enforced (Kelleher and Kenchington, 1992). This will require the coordinating agency to identify the various stakeholder groups and develop strategies for working with these groups. For example, planning documents should be accessible, short, and presented in nontechnical, easily understandable language. Participatory mechanisms should not be limited to public hearings but should include less formal settings more conducive to open discussion. Finally, the concerns of stakeholders must be documented in the preparation of management plans (Suman et al., 1999). In practice, management decisions will be based on incomplete knowledge and understanding; however, most plans involve some research to narrow the range of possibilities for MPA selection. If funds are limited, a competent plan can be developed with basic descriptions of the physical, biological, and socioeconomic characteristics of an area. A management plan for an MPA will require revisions over time to address shortcomings in the performance of the MPA and advances in understanding of how the MPA contributes to resource management. Hence, some flexibility

OCR for page 97
Page 123must be allowed for adjusting the zoning and levels of protection within MPAs. Lack of flexibility currently constrains the National Marine Sanctuary Program because of pledges not to restrict commercial fishing operations made during the designation of some sites (NAPA, 2000). Review of zoning plans and performance should be conducted at intervals short enough for management to respond to problems but not so frequent that it becomes prohibitively expensive—five to seven years is often a suitable period. Such a review should include monitoring impacts, patterns of use, and enforcement. The importance of a rigorous monitoring and evaluation program for the success of MPAs is explored in detail in Chapter 7. Management Tools to Supplement MPAs Until recently, the establishment of MPAs has not been viewed in the context of the marine ecosystem as a whole. In planning past MPAs, people have often failed to consider how the surrounding region and human activities may affect the MPA, and vice versa. However, good management of surrounding areas will increase the efficacy of MPAs. With precautionary management, a smaller total area in fully protected reserves may suffice to yield the same conservation benefit. Thus, it is essential to manage activities beyond an MPA's boundaries to secure its long-term viability. One approach to coupling the use of MPAs with coastal zone management is to create contiguous marine and terrestrial protected areas. Local governments usually have an important role in controlling development and other activities in adjacent coastal areas, as a form of integrated coastal zone management. Because polluted runoff, drainage of wetlands, and diversion of freshwater streams and rivers negatively affect the health of adjacent marine areas, the success of an MPA will in part be dependent on the community's commitment to manage adjacent coastal areas to improve or maintain the quality of the marine environment. The most obvious external influences that should be controlled include pollution and overutilization of living resources. Effort- and quota-based management, as well as additional spatial and temporal controls on fishing, can be applied to supplement protection using reserves. The type of additional measures needed to regulate fishing will vary widely among fish stocks and areas. Some of these other measures and their application are described in Chapter 3. Many options will prove useful for spatially controlling fishing outside MPAs, such as establishing area and temporal closures to particular methods of fishing. Temporal closures have long been used in single-species fishery management. In contrast to permanent closures, they have been broadly accepted as a management tool. Temporal closures can be a primary means to try to confine catches to targeted levels or to distribute fishing effort over a season. In fact, within-season temporal closures, combined with gear restrictions, are among the

OCR for page 97
Page 124most common methods used to control fishing effort. Temporal closures are also implemented to protect fishery resources at times when they are particularly vulnerable, such as when fish are aggregated on spawning grounds. MPAs will also shift patterns of fishing effort, and management plans should be designed to take these expected changes into account. Temporal closures aimed at limiting fishing mortality can be effective if regulators correctly anticipate or control the fishery's reaction to time (and area) closures. A closure in one area will typically result in increased effort elsewhere. In some cases, rotating areas of closure for specified periods has been used to promote growth of young animals, allowing them to reach more valuable sizes. This approach combines temporal and spatial closures to regulate fishing and could supplement benefits from fully protected reserves. As an example, the State of Washington has instituted rotating closures in its sea urchin fishery to control effort and allow populations to recover to marketable sizes and quantities. Rotating closures may help protect habitat and biological communities in addition to target species by allowing areas altered by fishing gear to recover during respites from fishing. However, if the period of closure is short, the area may have insufficient time to recover, jeopardizing the full recovery of the target stock. Longer-term closures may be instituted as single-species refuges from fishing. In this approach, the goals focus on rebuilding or restoration, with long-term success dependent on more precautionary management after the stock recovers. One recent long-term closure in California, implemented for chinook salmon (Oncorhynchus tshawytscha) in the Klamath River area, closed the entire (mixed-species) salmon fishery off the coast to allow recovery. In another example, closure of the severely depleted striped bass (Morone saxatilis) fishery along much of the east coast of the United States in the 1980s was effective in promoting recovery of the species and reestablishment of the fishery (Field, 1997; Richards and Rago, 1999). Unfortunately, there are few alternatives to long-term closures of large areas when fish populations have collapsed, and restoration of the abundance and age structure of the depleted population may require many years. One goal of MPAs is to provide insurance against stock collapse (Chapter 5), reducing the need for such drastic measures. Single-species closed areas lack many of the key conservation benefits of permanent reserves, but they provide an important tool to control fishing effort and supplement more comprehensive MPAs. There are some examples of temporal closures to address multispecies or ecosystem concerns rather than single-species fishery management. For instance, closure of large areas in the Bering Sea around Steller's sea lion (Eumetopias jubatus) habitat during the walleye pollock (Theragra chalcogramma) fishing season is an example of the use of temporal area closures with broader conservation objectives. Although temporal closures have value as a tool for fishery management, this approach does not yield the benefits sought with the establishment of MPAs.

OCR for page 97
Page 125There are cogent ecological and socioeconomic arguments for establishing MPAs with long-term, defined boundaries, although there has to be flexibility for adjusting zones, such as ecological or fishery reserves, within MPAs to maximize effectiveness. Damage to habitats and fish populations from human activities can occur very quickly, but recovery often requires a long period of time. For example, biogenic habitat such as deep-sea corals once damaged by trawling could take many decades to recover. Also, when fish stocks collapse, recovery may be slow, especially for long-lived species that take many years to reach reproductive maturity. If reserves are designed in the context of supporting the surrounding ecosystem they can serve as the ecological equivalent of a trust fund: the fish stocks and habitat within a reserve will provide a long-term investment in the productivity of the ecosystem as a whole.