CREATION OF MARINE RESERVES AND INCENTIVES FOR BIODIVERSITY CONSERVATION

Abstract Despite a number of benefits, marine reserves provide neither incentives for fishermen to protect biodiversity nor compensation for financial loss due to the designation of the reserves. To obtain fishermen's support for marine reserves, some politicians have suggested that managers of new marine reserves should consider subsidizing or compensating those fishermen affected by the new operations. The objective of this paper is to apply principal–agent theory, which is still infrequently applied to fisheries, to define the optimal reserve area, fishing effort, and transfer payments in the context of symmetric and asymmetric information between managers and fishermen. The expected optimal reserve size under asymmetric information is smaller than that under symmetric information. Fishing efforts encouraged with a transfer payment are always less compared to those without payment. This reflects the fact that as the manager induces the fishermen to participate in the conservation program, the fishermen will take into account their effects on fish stock by decreasing their effort. Examples are also supplied to demonstrate these concepts.     

ECONOMICALLY OPTIMAL MARINE RESERVES WITHOUT SPATIAL HETEROGENEITY IN A SIMPLE TWO‐PATCH MODEL

Bioeconomic analyses of spatial fishery models have established that marine reserves can be economically optimal (i.e., maximize sustainable profit) when there is some type of spatial heterogeneity in the system. Analyses of spatially continuous models and models with more than two discrete patches have also demonstrated that marine reserves can be economically optimal even when the system is spatially homogeneous. In this note we analyze a spatially homogeneous two‐patch model and show that marine reserves can be economically optimal in this case as well. The model we study includes the possibility that fishing can damage habitat. In this model, marine reserves are necessary to maximize sustainable profit when dispersal between the patches is sufficiently high and habitat is especially vulnerable to damage.     

USING RESERVES TO PROTECT FISH AND WILDLIFE SIMPLIFIED MODELING APPROACHES

ABSTRACT. This paper investigates theoretically to what extent a nature reserve may protect a uniformly distributed population of fish or wildlife against negative effects of harvesting. Two objectives of this protection are considered: avoidance of population extinction and maintenance of population, at or above a given precautionary population level. The pre‐reserve population is assumed to follow the logistic growth law and two models for post‐reserve population dynamics are formulated and discussed. For Model A by assumption the logistic growth law with a common carrying capacity is valid also for the post‐reserve population growth. In Model B, it is assumed that each sub‐population has its own carrying capacity proportionate to its distribution area. For both models, migration from the high‐density area to the low‐density area is proportional to the density difference. For both models there are two possible outcomes, either a unique globally stable equilibrium, or extinction. The latter may occur when the exploitation effort is above a threshold that is derived explicitly for both models. However, when the migration rate is less than the growth rate both models imply that the reserve can be chosen so that extinction cannot occur. For the opposite case, when migration is large compared to natural growth, a reserve as the only management tool cannot assure survival of the population, but the specific way it increases critical effort is discussed.     

FISHERY BENEFITS OF FULLY PROTECTED MARINE RESERVES: WHY HABITAT AND BEHAVIOR ARE IMPORTANT

ABSTRACT. Fully protected marine reserves, areas that are closed to all fishing, have attracted great interest for their potential to benefit fisheries. A wide range of models suggest reserves will be most effective for species that are relatively sedentary as adults but produce offspring that disperse widely. Adult spawning stocks will be secure from capture in reserves, while their offspring disperse freely into fishing grounds. Such species include animals like reef fish, mollusks and echino‐derms, and models typically indicate that when they are over‐fished, catches will be higher with reserves than without. By contrast, the same models suggest that reserves will be ineffective for animals that are mobile as adults species like cod, tuna or sharks. They remain vulnerable to fishing whenever they move outside reserves. Unfortunately, most models lack sufficient realism to effectively gauge reserve effects on migratory species. They usually assume that individuals are homogeneously distributed in a uniform sea and move randomly. They also assume that fishers hunt at random. Neither is true. For centuries, fishers have targeted places and times when their quarry are most vulnerable to capture. Protecting these sites could have disproportionately large effects on stocks. Furthermore, models rarely take into account possible benefits from improvements in habitat within reserves. Such changes, like increased biomass and complexity of bottom‐living organisms, could alter fish movement patterns and reduce natural mortality rates in ways that enhance reserve benefits. We present a simple model of reserve effects on a migratory fish species. The model incorporates spatial variation in vulnerability to capture and shows that strategically placed reserves can offer benefits in the form of increased spawning stock and catch, especially when fishing intensities are high. We need to develop a new generation of models that incorporate habitat and behaviour to better explore the utility of reserves for mobile species. Migratory behavior does not preclude reserves from benefiting a species, but it demands that we apply different principles in designing them. We must identify critical sites to species and develop reserve networks that focus protection on those places.     

MARINE PROTECTED AREAS IN THE HIGH SEAS AND THEIR IMPACT ON INTERNATIONAL FISHING AGREEMENTS

Abstract Marine protected areas (MPAs) are gaining momentum as tools within fisheries management. Although many studies have been conducted to their use and potential, only few authors have considered their use in the High Seas. In this paper, we investigate the effects of fish growth enhancing MPAs on the formation of regional fisheries management organisations (RFMOs) for highly migratory fish stocks. We argue that in absence of enforcement MPAs constitute a weakest‐link public good, which can only be realized if everyone agrees. We combine this notion with a game theoretic model of RFMO formation to derive potentially stable RFMOs with and without MPAs. We find that MPAs generally increase the parameter range over which RFMOs are stable, and that they increase stability in a number of cases as compared to the case without MPAs. They do not necessarily induce a fully cooperative solution among all fishing nations. In summary, results of this paper suggest a positive role for MPAs in the High Seas.     

FISHERIES AND MARINE PROTECTED AREAS: A SPATIAL BIOECONOMIC ANALYSIS OF DISTRIBUTIONAL IMPACTS

Abstract Marine protected areas (MPAs), used increasingly as a tool for conservation of ocean and coastal environments, typically interact with fisheries. Indeed, implementation of an MPA in a coastal region will likely affect fishing communities along that coast but to differing degrees depending on their location relative to the MPA. The resulting creation of “winners” and “losers” has implications for the acceptance and long‐term viability of the MPA. This paper develops a spatially explicit bioeconomic simulation model to assess the distributional implications resulting from creation of a no‐take MPA. The key assumption is that this results in certain fishers being displaced from the MPA to new fishing locations, leading to decreased fishing time and increased costs. Is it possible for those being displaced to end up as “winners” in the fishery? Analysis of the model indicates that such an outcome can occur in certain circumstances, notably if the biological effects of the MPA produce (i) improved ecosystem health inside the MPA, such that fish stock carrying capacity increases; or (ii) to some extent, high fish stock migration rates between neighboring areas. The results indicate that in creating MPAs, careful attention to their design is needed in order to deal with corresponding distributional impacts on fishing communities.     

BIOECONOMIC INTERACTIONS IN AN ESTABLISHED FISHING EXCLUSION ZONE: THE GULF OF CASTELLAMMARE,NW SICILY

ABSTRACT. Fishing exclusion zones have become a key management tool for habitat protection and species conservation within fisheries. In many instances, where overfishing or habitat destruction is taking place, they are being promoted strongly. For fisheries management, their use is widespread and their popularity growing. It is clear that in some cases marine protected areas may be crucial to sustaining resources. Most research to date has considered the biological or ecological effects of such reserves. However, little real analysis has been published that takes into account the links between the biology and the economics of the fisheries involved, making the economic benefits to fisheries less clear. This paper considers an exclusion zone which was implemented in 1990 in the Gulf of Castellammare, Sicily in the form of a trawl ban, modeling the potential effects of future policy in this area. The success of the trawl ban has far exceeded expectations, and it is simulated that it may be advantageous, under strict conditions, to relax the ban in part for some of the year.     

A MODEL OF TROPICAL MARINE RESERVE‐FISHERY LINKAGES

ABSTRACT. The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. In this paper we examine the contribution of fully protected tropical marine reserves to fishery enhancement by modeling marine reserve‐fishery linkages. The consequences of reserve establishment on the long‐run equilibrium fish biomass and fishery catch levels are evaluated. In contrast to earlier models this study highlights the roles of both adult (and juvenile) fish migration and larval dispersal between the reserve and fishing grounds by employing a spawner‐recruit model. Uniform larval dispersal, uniform larval retention and complete larval retention combined with zero, moderate and high fish migration scenarios are analyzed in turn. The numerical simulations are based on Mombasa Marine National Park, Kenya, a fully protected coral reef marine reserve comprising approximately 30% of former fishing grounds. Simulation results suggest that the establishment of a fully protected marine reserve will always lead to an increase in total fish biomass. If the fishery is moderately to heavily exploited, total fishery catch will be greater with the reserve in all scenarios of fish and larval movement. If the fishery faces low levels of exploitation, catches can be optimized without a reserve but with controlled fishing effort. With high fish migration from the reserve, catches are optimized with the reserve. The optimal area of the marine reserve depends on the exploitation rate in the neighboring fishing grounds. For example, if exploitation is maintained at 40%, the ‘optimal’ reserve size would be 10%. If the rate increases to 50%, then the reserve needs to be 30% of the management area in order to maximize catches. However, even in lower exploitation fisheries (below 40%), a small reserve (up to 20%) provides significantly higher gains in fish biomass than losses in catch. Marine reserves are a valuable fisheries management tool. To achieve maximum fishery benefits they should be complemented by fishing effort controls.     

PLANNING MARINE PROTECTED AREAS: A MULTIPLE USE GAME

Abstract The EU Marine Strategy Directive (MSD) has a regional focus in its implementation. The directive obliges countries to take multiple uses and the marine strategies of neighboring countries into account when formulating marine strategies and when designating marine protected areas (MPAs). We use game theoretical analysis both to find the optimal size of MPAs with multiple uses by multiple countries and to investigate the influences of multiple uses on cooperation. To this end, we develop a model in which two specific uses, fisheries and nature conservation, by multiple countries are considered in a strategic framework. The results of the paper suggest that EU marine policy such as the MSD and the coming Maritime Policy may help to secure the highest possible benefits from these MPAs if these policies induce cooperation among countries, but only if policies force countries to consider all possible benefits of MPAs. In fact cooperation on a single issue may give a worse outcome than the noncooperative equilibrium. The results also indicate that cooperation may be hard to achieve because of defector incentives, and therefore policy measures should be strict in enforcing cooperation on all possible uses of MPAs.     

NATURAL RESOURCE MODELING: ALLOWING FOR INCONSTANT PROBABILITY OF DETECTION AND FREQUENCY MEASURES OF VIOLATION WITHIN DYNAMIC DETERRENCE FISHERY MODELS

Abstract. The dynamic deterrence model (DDM) represents an analytical framework widely used for analyzing compliance with fishery regulations aiming for sustainable fishery management. However, applications of the DDM have so far been limited to the case of constant probability of detection that assumes independence of the length of time to detection. This paper modifies the DDM to allow for more flexible and broader specification by introducing, for the first time, two important variables to the supply of offences function, namely evasion activity and enforcement efforts and accommodating inconstant probability of detection specifications. Determinants of probability of detection are specified and important potential extensions of the modified DDM are discussed in this paper. The relative magnitude of the effects of each of these determinants on probability of detection, however, remains an important empirical question that requires further investigation for prioritization of policy actions.     

OPTIMAL TAXES FOR POLLUTION REGULATION: DYNAMIC,SPATIAL AND STOCHASTIC CHARACTERISTICS

The paper develops a model that incorporates the dynamic, spatial and stochastic aspects of environmental pollution. Conditions for optimal resource allocation between output production and pollution abatement processes are derived. Optimal emission (Pigouvian) taxes which may be used to efficiently regulate pollution in each region are determined. The pattern of emission taxes over time and their relative sizes among different regions are additionally explored with the help of a simplified numerical example.     

信息成本、博弈规则与经济效率:兼议国有资产运营的制度选择

本文假设委托人或监督人能够以一定成本收集信息从而能依一定概率观察到影响委托人报酬的生产力水平 ,研究了存在信息传递成本的多委托人模型、零信息传递成本的多委托人模型和委托人 -监督人 -代理人模型 ,比较了不同的博弈规则或制度安排在均衡状态下的信息分布与经济体效率 .本文的研究结论表明 ,给定委托人或监督人的信息成本与信息处理能力 ,博弈规则是决定信息分布与经济体效率的关键因素 .存在信息传递成本时 ,由于坐便车行为 ,信息分布的不对称程度最为严重 ,也具有最低的效率 .零信息传递成本的多委托人模型中 ,信息不对称程度最弱 ,并且在很弱的条件下具有最高的效率 .委托人 -监督人 -代理人模型中 ,仅当监督人具有充分低的信息收集成本和充分高的信息处理能力时 ,才有可能具有较高的效率 .就本文的模型所支持的结论而言 ,国有企业的公司制改造 ,并降低资本市场传递与处理信息的成本 ,是更富于效率的一种制度安排 .相反 ,由于作为监督者的国有资产管理部门并不佣有产权 ,它没有足够的动机去认真履行监督职责 ,同时 ,诱导监督者其不与代理人串通作弊的成本之高昂 ,都将进一步降低这种制度安排下国有资产运营的效率 .