Threats to conservation benefits other than those related to fishstocks include ecosystem conversion, such as mangrove deforestation, pollution from aquacultureand tourism, and damaging fishing practices such as dynamite fishing, which all require manage-ment actions other than enforcing fishing restrictions. In addition, management actions can notonly prevent damages but also create benefits, such as management decisions about tourism infra-structure. Management decisions might also reflect differences between artisanal, commercial, andrecreational fishers, with the importance of recreational fishers often overlooked in MPA analysis(Arlinghaus et al. 2019)

overcoming open access overexploitation through community institutions with implicit or explicitenforcement of community rules.

Alternative income-generating projects for potential MPApoachers can induce lower levels of illegal fishing by making fishing relatively less attractive or byreducing time available for fishing (Albers et al. 2021). Programs that compensate local people forreduced fishing access through benefits-sharing or payments, however, may not induce reductionsin illegal fishing if the programs are not well linked to community pressure or to monitoring withconsequences (Robinson et al. 2014

Although much of the MPA network expansion will occur in lower-income countries, littleof the economics literature addresses widely used, incentive-based mechanisms to limit illegalextraction in MPAs in those countrie

s. Management decisions to mit-igate human threat within MPAs typically fall into two categories: monitoring and enforcementof restrictions and incentives through compensation with monitoring.

Most analysis of no-take zones assumes that the zones deter all harvest in the MPA, with-out consideration of the enforcement costs incurred to deter harvest. By ignoring enforcementcosts, such frameworks cannot inform management decisions about MPAs and can lead to falsepredictions of MPA impact, which generates inappropriate siting decisions

differentiating zones to exploit synergies across zones. In terrestrial settings, economic modelingof spatial decisions by extractors informs the appropriate size and location of zones around corerestricted zones, but such frameworks are not incorporated into software or decision frameworksfor defining zones and zone use restrictions (Albers 1996, 2010; Robinson et al. 2011, 2013).In addition to having restrictions on fishing by amount or location, multiple-use MPAs canrestrict who has fishing rights and what fishing gear is permitted. Fishing gear restrictions mightinclude carrying capacity–damaging activities like dynamite fishing or fish growth–impairing gearlike fine mesh nets

find that focusing on the no-takezone without addressing local community resource use leads to negative consequences for com-munities but the analysis uses implicit frameworks to define community needs and access. Greenet al.’s (2013) MPA network design guide for practitioners calls for the creation of large multiple-use MPAs that contain zones with different permitted uses, including no-take reserves

report that 94% ofMPAs are not no-take reserves and allow some fishing, which they argue limits MPA contributionsto biodiversity conservation. Other ecological studies describe higher biomass in no-take MPAsthan partially protected MPAs (Sala & Giakoumi 2018). In terrestrial PAs, economists find thatmultiple-use PAs provide more protection against deforestation than do more restrictive PAs andhypothesize that people’s threats to PA resources differ across IUCN categories of PAs in the con-text of incomplete enforcement (Pfaff et al. 2014). Similarly, Arias et al. (2015) find higher MPAeffectiveness through fisher compliance in MPAs that permit but regulate fishing.

Metcalfe et al. (2015) emphasize the interactions between the configuration, number, andsize of MPA sites in assessing trade-offs including socioeconomic outcomes. Sanchirico (2004)finds settings in which one reserve provides lower rents than two reserves. Albers et al. (2020a)find that the number and location of equal-sized MPAs in an MPA network change nonlinearlywith increases in management budgets. Beyond these studies, little economic analysis considers thecomplex spatial decisions of fishers in response to networks of MPAs to inform network decisions.

For settings in which subpopulations of species cross jurisdictional boundaries, the MPA sitingdecision is complicated by the interests of both jurisdictions and the public good nature of theMPA. Strategic interactions lead to suboptimal MPA locations (Ruijs & Janmaat 2007). Undersome conditions and species characteristics, transboundary MPAs can resolve the overexploitationof boundary-crossing fish and lead to higher stocks and harvests for both countries (Costello &Molina 2021)

nchirico (2004) emphasizes thatMPA siting requires a marinescape perspective that reflects the characteristics of each patch andtheir connections through dispersal rather than basing MPA location choices on single patchcharacteristics.

n MPA models that choose MPA size, Yamazaki et al. (2015) and Albers et al. (2020a)find that larger MPAs can lead to lower aggregate stocks due to larger no-take reserves that arenot well enforced and suffer illegal harvest; the MPA size interacts with management actions. Intheir empirical work, Arias et al. (2015) find that compliance with MPAs is higher with smallerMPAs. The choice of MPA size contains trade-offs between an area’s impact on management costs,threats to the system, and benefits based on fish movement and ecosystem services, with remainingquestions about when those trade-offs lead to preferences for large or small MPAs

Conservation area targets, as in 30X30, have raised interest and skepticism in largeMPAs. Advantages of large MPAs include allowing interactions between different ecosystemswithin one MPA, more holistic management, and economies of scale in management, althoughmonitoring costs could increase with are

In addition, thehuman threats that MPAs seek to limit include nonfishing actions, such as ecosystem conversionfor aquaculture or reef damage from tourism. To make appropriate MPA design choices in set-tings where fish biomass is not the primary driver of conservation benefits and fish harvests are notthe sole threat, economists could work in interdisciplinary groups to depict relevant productionfunctions, define management cost functions, and assess the impact of MPA design and manage-ment choices on the responses of people who generate value, such as through tourism, and whogenerate conservation losses, such as through pollution. Bringing economic tools to bear on MPAchoices to deliver conservation benefits can improve the efficient allocation of limited funds forthat conservation and therefore provide more conservation benefits per budget

Most MPAs have both conservation and fishery goals but few analyses treat these goals jointly,due, in part, to the lack of valuation for many outcomes. Analyses that design MPAs that are robustacross various desirable outcomes could help achieve dual goa

Further economic analysis of what influences the spatial response of artisanal fishers to MPAs,what management actions and programs work to foster compliance with restrictions, and howvarious sets of restrictions inform fisher decisions, is necessary to facilitate the expansion of MPAnetworks across the developing world to generate conservation and economic benefits

Analyses outside of the economics literature explore LMIC MPA decisions but in ways thatmay not adequately reflect people’s decisions in such settings. As elsewhere in the systematicconservation planning literature, Kockel et al. (2020) use lost fishing grounds as the metricof impact on artisanal fishers rather than the fisher response to MPAs. To evaluate trade-offsbetween biodiversity and socioeconomic values, Teixeira et al. (2018) estimate fisher opportunitycosts in data-poor regions but use habitat characteristics alone to estimate the spatial distributionof those costs. Grantham et al. (2013) compare several zoning and MPA configurations but useproximity between communities and restrictive zones as a metric to determine an equitabledistribution of community impact.546 Albers • Ashworth

Much of the expansion of MPA networks is likely to occur in the developing world, but littleresearch uses developing country characteristics defined in the environment-development eco-nomics literature to examine those decisions (Marinesque et al. 2012). First, individuals makedecisions within subsistence and semi-subsistence settings, missing or thin markets, householdlabor and capital constraints, budget constraints, and high poverty, which can contribute todistributions of effort. S

Yet, dozens of conservation science articles describe conservationeffectiveness and MPA impact analysis that do not consider these advances in impact analysis,such as comparing outcomes in unprotected areas (Friedlander et al. 2017, Selig & Bruno 2010)and comparing the outcome measures before/after an MPA has been placed without consideringthe counterfactual of no-MPA (Savina et al. 2013).

In the last decade, economics journals have contained few articles with MPAs as the central topic,despite the emphasis on expanding MPAs in conservation policy. The reasons behind this paucityof articles could include editorial opinions that MPAs are not an important economic issue, thatthe relevant questions have been answered, and that the techniques used to explore MPAs are notappropriate for economics journals; or perhaps economists simply are not engaged with marineconservation issues. In contrast, the conservation science literature, including interdisciplinaryjournals, contains thousands of articles about MPAs, some with economists as authors. Althoughpublishing in outlets with wide readership, particularly practitioners and interdisciplinary re-searchers, is important for furthering knowledge about MPAs and informing policy, the lack ofarticles in economics journals makes it difficult to evaluate which articles use economics-basedmethods in a rigorous and appropriate way because most such publications are not reviewed byeconomists.

Given the proposed expansion of MPAs, randomizingearly MPA network extensions to create an experimental setting for analysis would provide criticalinformation about what characteristics of MPAs provide net conservation and economic benefits(Ferraro 2009, Ferraro & Pattanayak 2006). In addition to the challenges of convincing policymakers to embrace that sort of experimental design in MPA expansions, MPA impact analysis iscomplicated by the treatment of much of the marinescape through the spatial connections of theecological and economic systems. Nonetheless, using rigorous methods to assess MPA impact iscritical to generating efficient conservation policy

Overall, the MPA economics literature emphasizes the importance of the spatial behavior ofboth the resources in the marine ecosystem and people in the marinescape, given that MPAs areinherently spatial policies

using such a frame-work forces the integration of ecological and economic decisions, including people’s behavior, toachieve positive outcomes for conservation, social welfare, economic values, or their combina-tions. Even for pure conservation outcomes, MPA decisions must reflect the responses of peoplebecause people’s reactions to the MPA influence conservation and other outcomes. People respondto all aspects of the MPA design decisions: The location, size, and configuration inform people’sdistance-based costs and the distribution of the resource across the marinescape; the type and levelof restrictions within the MPA influence people’s trade-offs among locations and activities; andmanagement decisions, including enforcement to influence the net returns from actions within theMPA.

Because fish and people move across MPA boundaries, most MPA analyses consider both theMPA and the surrounding marinescape. In fishery economics, the ecological system is often de-picted as a marinescape of patches of fish subpopulations, with dispersal among subpopulations ina metapopulation (Sanchirico & Wilen 1999), potentially with some patches as hotspots (Schnier2005). That said, there are settings in which the scale of a subpopulation is larger than the scale ofMPAs, settings in which the policy scale does not permit distinguishing between subpopulations,and other settings in which a metapopulation does not apply.

) literature assessment finds that MPAs contribute to food security, socialwell-being, and political power in local communities, with heterogeneous impact on differentgroups. Overall, considering the fishers’ and people’s responses to MPAs is an important aspect ofdesigning MPAs to achieve conservation and economic outcome

The economics literature on MPAs is clear on the importance of considering people’s—typicallyfishers’—responses to MPAs in order to make decisions about MPAs or to assess MPA impact(Albers et al. 2020a, Bennett et al. 2020, Dépalle et al. 2020, Hannesson 1998, Reimer & Haynie2018, Smith & Wilen 2003, Sultan 2020, Zhang & Smith 2011). In particular, MPA economicanalyses emphasize the importance of the spatial response of fisher behavior to the spatial policyof MPAs (Albers et al. 2020a, 2021; Sanchirico & Wilen 2001; Smith & Wilen 2003). Althoughconservation scientists describe a response of fishers to MPAs, those descriptions—both modelingand empirical—often fail to consider important aspects of people’s decisions. In some cases, con-servation scientists evaluate MPAs with assumptions of no fisher redistribution of effort (Selig &Bruno 2010, Sutcliffe et al. 2015) or redistribution of effort with total effort constant (Friedlanderet al. 2017, Klein & Watters 2020, Savina et al. 2013). Smith & Wilen (2003) find that typicalassumptions about fisher response bias predicted outcomes in favor of MPAs when fuller descrip-tions of fisher spatial behavior find other outcomes. For economists to inform MPA decisions,continued development of predictive models and empirical analyses that provide the microeco-nomics of fisher decisions is critical.

his empirical work suggests that the simpler models of fishing effort allocation across spacemay not be sufficient for predicting the response to MPAs, the resulting outcomes, and thereforethe choice of MPA sites and sizes

Still,most economic analysis does not explicitly address the dispersal matrix of marine species betweensites or subpopulations. Bauer et al. (2010) and Albers et al. (2022a) demonstrate the importanceof the dispersal matrix itself for decisions about conservation of terrestrial species.

For ex-ample, a conservation goal of maximizing the number of species in an MPA requires the use ofecological frameworks that depict interactions among species and how species diversity respondsto policy, such as protecting reefs from tourists. Similarly, conservation goals to improve stocks ofnonharvested fish require ecological system models integrated with economic policy frameworksor ecosystem-based management approaches to assess policies, including, but not limited to,fishing restrictions

Marine protected areas (MPAs) provide both conservation and economicbenefits. Recent international conservation actors have called for a dramaticincrease in the are

As compared to terrestrial PAs, establishing MPAs faces lower start-up costs due to the lack ofprivate ownership of marine areas but potentially higher ongoing costs associated with enforcingaccess and use restrictions (Bohorquez et al. 2019). Waldron et al. (2020) predict that low- andmiddle-income countries (LMICs) will face 70–90% of the implementation costs of achieving30% PAs by 2030, which signals the need for international funding sources. Despite the promi-nence of paper parks and tight budget constraints for ongoing management and enforcementin lower-income countries, but also in wealthier countries, economic analysis of MPAs rarelyconsiders those costs in evaluation nor in siting decisions. In addition, little is known about thelevel of budgets required to make MPAs effective at generating economic or conservation gains.Gravestock et al. (2008) use regression analysis of surveys in 36 countries to determine what drivesbudgetary needs in MPAs, finding that those budgets are higher with large MPA sizes and higherMPA visitor numbers

MPA choices include thespecific location, configuration, and size of the MPA; the accepted uses and restrictions on useswithin the MPA; ecological and economic management decisions, including monitoring and en-forcement; and temporal choices. All of these choices face information gaps in how they influencethe creation of MPA benefits, particularly for conservation benefits beyond fish stock metrics.

The choicevariables include MPA location, size, configuration, restrictions, and management. The setting’sbio-geo-physical characteristics include the spatial distribution of ecological attributes, the spatialbehavior of the ecosystem such as fish dispersal, and system dynamics. People’s decisions in re-sponse to the MPA and its management create additional equations of motion due to their impacton the ecosystem. Budget constraints and local institutions form additional constraints. Proceed-ing from the objective function through these choice variables and constraints, we use this decisionframework to assess the economics literature’s status and contribution to MPA policy.2.1. Objective FunctionBeyond area targets, MPAs seek to generate conservation benefits, economic benefits, or both.Economists consider MPAs to maximize net social benefits or, more commonly, to maximize534 Albers • Ashworth

These widely used frameworks typically do not incorporate eco-nomic analysis approaches, even when addressing economic outcomes such as fishery harvests.While economic analysis of MPAs focuses on fishery outcomes, economic perspectives on peo-ple’s behavior in response to MPAs are particularly important because responses determine bothconservation and economic outcomes.

r more economic analysis of MPApolicy questions, including those around siting, design, restrictions, andmanagement choices; impact evaluation; responses of people; low-incomecountry settings and incomplete enforcemen

Capitán et al. (2020) compare MPA decisions across several goals, includingmaximizing income, extracted resource stocks, and unextracted sea turtle populations. Combin-ing modeling and empirics, Sultan (2021) considers the MPA impact on fish populations, biomass,and catch rates. Conservation science analyses find limited impact of MPAs on non-harvestedspecies (Endo et al. 2019, Montero-Serra et al. 2019, Welch et al. 2018). MPA tourism can alsoreduce conservation outcomes (Lopes et al. 2017, Monti et al. 2018, Velando & Munilla 2011).Hastings et al. (2017) show that marine reserves in a multispecies fishery can reduce bycatch with-out reducing yields of the target species.

Sanchirico et al. (2006) ask when establishing a no-take reserve willmaximize marinescape profits. Albers et al. (2020a, 2021) determine the optimal MPA to maximizeincome, comprising fishing income and onshore income, and to maximize marinescape stocks. Inthese frameworks, MPA benefits to marinescape fisheries through fish dispersal trade off againstthe lost fishing within the MPA

. People’s decisions in re-sponse to the MPA and its management create additional equations of motion due to their impacton the ecosystem

Conservation economists and scientistsview the objective of MPAs as providing a suite of conservation outcomes, including stemmingthe loss of biodiversity and ecosystem services, maximizing the number of species, creating MPArepresentation of diverse systems, increasing fish stocks for harvested or nonharvested species,resilience to climate change, and coral reef health (e.g., Almany et al. 2009, Bates et al. 2019,Davies et al. 2017, Game et al. 2009, Magris et al. 2018, Wilson et al. 2020). Most MPA economicanalyses consider both a fishery economic goal and a conservation goa

. Unliketerrestrial PAs, MPAs are commonly used as fishery management tools within a marinescape. Forboth conservation and poverty alleviation reasons, the United Nations’ Sustainable DevelopmentGoal 14 aims for larger MPA networks worldwide

Both the economics and conservationscience literatures consider MPA decisions and MPA impact, although theeconomics literature focuses on fishery economic outcome