Fishery externalities and biodiversity: Trade-offs between the viability of shrimp trawling and the conservation of Frigatebirds in French Guiana

Sustainable management of natural resources, and in particular fisheries, must take into account several conflicting objectives. This is the case in the French Guiana shrimp fishery for which profitability objectives imply a reduction in the fishing activity. On the one hand, this fishery has negative externalities on marine biodiversity due to discards. On the other hand, this fishery has positive externalities on the economy of the local community and interestingly enough on a protected seabird species in the area (the Frigatebird that feeds on discards). In this paper, we examine the viability of that system considering two sustainability objectives: an economic objective in terms of the profitability of the fishing activity, and a conservation objective in terms of the Frigatebird population. For that purpose, we have developed a dynamic model of that bioeconomic system and study here the trade-offs between the two conflicting objectives. It provides a means to quantify the necessary give and takes involving the economic and ecological objectives that would ensure a viable management solution. Our study confirms the relevance of the viability approach to address natural resource management issues, which should lead to the development of new tools for the arbitration of conflicting sustainability objectives. In particular, such tools could be used as a quantitative basis for cost–benefit analysis taking into account environmental externalities.     

海洋休闲渔业开发的实证研究——以青岛甘水湾为例

随着渔业环境的改变,我国的产业实践和学术研究不断探寻与总结休闲渔业的发展出路,以利休闲渔业的持续发展。文章通过对青岛市甘水湾村休闲渔业发展条件的分析以及发展现状的研究,提出抓住新机遇,升级休闲渔业的对策,以期为其他沿海地区发展现代休闲渔业提供借鉴。     

WELFARE‐MAXIMISING PRICING IN A MACROECONOMIC MODEL WITH IMPERFECT COMPETITION AND CONSUMPTION EXTERNALITIES

This paper develops a simple macroeconomic model with imperfect competition and consumption externalities, and uses it to examine whether the marginal cost pricing rule in the partial equilibrium framework can apply to the general equilibrium framework. It is shown that, for welfare to be maximised, average revenue should be set equal to marginal cost if consumption externalities are either absent or positive. However, for welfare to be maximised, average revenue should be set higher than marginal cost in the presence of negative consumption externalities.     

Fishery externalities and biodiversity: Trade-offs between the viability of shrimp trawling and the conservation of Frigatebirds in French Guiana

Sustainable management of natural resources, and in particular fisheries, must take into account several conflicting objectives. This is the case in the French Guiana shrimp fishery for which profitability objectives imply a reduction in the fishing activity. On the one hand, this fishery has negative externalities on marine biodiversity due to discards. On the other hand, this fishery has positive externalities on the economy of the local community and interestingly enough on a protected seabird species in the area (the Frigatebird that feeds on discards). In this paper, we examine the viability of that system considering two sustainability objectives: an economic objective in terms of the profitability of the fishing activity, and a conservation objective in terms of the Frigatebird population. For that purpose, we have developed a dynamic model of that bioeconomic system and study here the trade-offs between the two conflicting objectives. It provides a means to quantify the necessary give and takes involving the economic and ecological objectives that would ensure a viable management solution. Our study confirms the relevance of the viability approach to address natural resource management issues, which should lead to the development of new tools for the arbitration of conflicting sustainability objectives. In particular, such tools could be used as a quantitative basis for cost–benefit analysis taking into account environmental externalities.     

长江经济带休闲渔业产业化发展潜力评价与分析

在界定休闲渔业产业化概念的基础上,从经济、社会、产业和支撑四个方面,创新性地选取26项指标构建休闲渔业产业化发展潜力评价指标体系,采用因子分析法和层次分析法对长江经济带11个省份休闲渔业产业化发展潜力进行科学评价。结果表明,长江经济带休闲渔业产业化发展潜力呈现东部沿海地区和中部的湖北相对领先,中部其余省份和西部地区相对落后的分布格局。进一步采用聚类分析法将长江经济带休闲渔业产业化发展潜力划分为四个等级,并分析不同等级地区存在的优势和不足,据此提出促进各地休闲渔业产业化发展的建议。     

Optimal Harvesting of an Age-Structured Schooling Fishery

Biologists have criticized traditional biomass models in fishery economics for being oversimplified. Biological stock assessment models are more sophisticated with regard to biological content, but rarely account for economic objectives. This study includes a full age-structured population model for studying schooling fisheries and extends the delayed difference approach used in earlier studies. We take the total harvest as the choice variable, resulting in a simple analytical structure. The model produces optimal steady states that may be higher or lower compared to the delayed-difference formulation. The model is applied to the Baltic sprat fishery. Both ecological and harvesting cost data support specifying Baltic sprat as a schooling fishery. Given nonlinear harvesting costs, the optimal solution is a path toward a steady state with smooth annual harvest and population age structure. Sensitivity analysis shows that the optimal solution is highly dependent on the population level of the sprat’s main predator Baltic cod. A linear cost function and an interest rate below 9 % imply pulse fishing instead of smooth continuous harvesting. Given nonlinear harvesting cost, the optimal steady state yield is rather insensitive to changes in the interest rate. However, under a high cod scenario, interest rates of 10 % or higher implies that no optimal steady state exists.     

Creating Asset Accounts For A Commercial Fishery Out Of Equilibrium: A Case Study Of The Atlantic Sea Scallop Fishery

This paper demonstrates a methodology for constructing asset accounts for a commercial fishery in which the stock, harvest, and effort level are out of sustainable equilibrium. The paper adopts the framework used by the U.S. Department of Commerce Bureau of Economic Analysis in its preliminary 1993 Integrated Economic and Environmental Accounts and follows methodologies recommended by the National Research Council committee constituted to review those efforts. The accounts were constructed for the period 1985 to 1995 for the Atlantic sea scallop fishery, a significant commercial fishery, using information obtained with the cooperation of the National Marine Fisheries Service from existing databases constructed for management purposes. No significant additional data collection was required for the purpose of this study. Differences between the net rent and user cost values of the stocks over this period indicate the inefficient exploitation of immature scallop populations.     

Corrective Taxes under Oligopoly with Inter-Firm Externalities

Pollution externalities between polluters should be taken into account in the design of corrective taxes. When the externalities are substantial and/or the number of polluters is large, the effluent levies on these firms do not necessarily result in a deadweight loss. Consequently, the second-best tax exceeds the marginal social cost of pollution. A more general rule is that the tax rate should be greater than the marginal social cost of pollution if and only if a marginal increase in the tax rate results in opposite effects on the changes of equilibrium emission level and output.     

Harvesting Preemption, Industrial Concentration and Enclosure of National Marine Fisheries

This paper explores how harvesting technology can affect firms' internalisation of common pool externalities and the incentives for expanding firm's size. Focusing on supply side non-pecuniary externalities, our closed-entry harvesting competition model suggests that when marginal harvesting costs are weakly sensitive to common pool externalities, atomistic competition is likely to remain, other things equal, as the predominant industrial structure in the fishery. The avenue for increasing industrial concentration is modelled via Stackelberg leadership which offers the option of preempting rivals' production. In our static modelling, a fishery subject to Stackelberg signalling results in higher overfishing versus the case of a highly decentralised harvesting sector (proxied by the use of Nash conjectures). Given that static optimising behaviour could be interpreted as a result of entry controls and other fishing regulations being widely perceived as ineffective controls, the obtained overfishing ranking suggests that in fisheries where strategic preemption in production is feasible, but where entry controls and other important regulations on fishing effort are considered to be ineffective, overfishing is likely to remain the predominant outcome, even if other incentives promote evolution towards a more concentrated industry structure. When the fishery is already overpopulated by numerous small firms, whatever advantages large firms may have in terms of profitability, numerous small-scale fishermen tend to make up for in the political arena. This imposes constraints on the politically feasible fishing regulations. We use a second best welfare benchmark to illustrate resulting policy trade-offs.     

A Bioeconomic Analysis of the Northern Baltic Salmon Fishery: Coexistence versus Exclusion of Competing Sequential Fisheries

We develop a bioeconomic model of the northern Balticsalmon fishery that takes into account thesimultaneous harvest of wild and reared salmon. Weassess the optimal harvest allocation between thecommercial offshore, inshore, and estuary fisheries,and the recreational river fishery that sequentiallyharvest the salmon stock. We restrict the solution tospawning stocks sufficient to preserve the wildsalmon. Empirical results suggest closure of theoffshore and inshore fisheries. Optimal managementenhances the wild stock, and results in substantialeconomic gains to the fishery. Current fisheryregulation improves the performance of the fisheryover open access, but fails to utilize the fullproductive potential of the resource.     

Valuing water level changes in reservoirs using two stated preference approaches: An exploration of validity

The combination of travel cost (TCM) and contingent behaviour (CB) methods is a relatively new research avenue in the recreational valuation community. Contrary to simple TCM applications, TCM-CB facilitates the ex ante valuation of marginal welfare effects resulting from environmental quality or quantity changes, similar to the contingent valuation method (CV). Even though TCM-CB is highly policy relevant, i.e. to inform changes in management regimes at recreational sites, the validity of estimates has hardly received any attention and little is known about the performance of TCM-CB compared to CV. In this paper, TCM-CB and CV are explored with respect to several validity tests in a case study on the recreational effects of water level changes in a reservoir. Overall, the findings reveal that TCM-CB and CV perform equally well in terms of theoretical validity, but that the marginal recreational value varies significantly between the two methods. We also observe that both methods face similar internal difficulties with respect to the stability of values when the order of a set of valuation questions is changed.     

Variable unit costs in an output-regulated industry: The Fishery

Departing from general cost theory of the firm and bioeconomic theory of the fishery, this study contributes with an empirical examination of how variable unit costs in a Norwegian demersal and pelagic fishery depend on output and the fish stock. The identification of the separate effects that the two factors have on costs is not common in the literature. Three Norwegian fleets fishing Norwegian spring spawning herring (Clupea Harengus) and five Norwegian fleets fishing Northeast Arctic cod (Gadus Morhua) are evaluated. The findings indicate that variable unit costs fall in output in both fisheries. The results also show that variable unit costs fall in fish stock in the demersal fishery, but with a stock elasticity of variable unit costs in absolute terms significantly less than 1. These results are of relevance to a manager seeking the optimal harvest rule and to understand fishermen's incentives when individual vessel quotas are reduced.     

Cooperative and Non-Cooperative Exploitation of the Arcto-Norwegian Cod Stock

A two-agent model for the exploitation of the Arcto-Norwegian cod stock is developed to investigate the economic benefits that can be realized from the resource, and the effect of exploitation on stock sustainability under cooperation and non-cooperation. The two agents are identified in this study as a trawl fishery versus a coastal fishery. Unlike in Munro (1979), where conflicts in the management strategies of agents arise from differences in the perceptions of the discount factor, fishing effort costs, and consumer preferences, here conflicts arise mainly from the differences in fishing gear and grounds, and the age group of cod targeted by the two agents. Using a game theoretic framework, we show that given available data, the optimum optimorum is obtained under cooperation with side payments and no predetermined harvest shares, in which case the coastal fishery buys out the trawl fishery. However, sensitivity analysis shows that if the price premium assumed for mature cod is taken away, the trawl fishery takes over as the producer of the optimum optimorum.     

Spatial-dynamic seawater intrusion and pumping cost externalities in a confined aquifer

This paper analytically develops the economic theory of seawater intrusion in confined aquifers and, in the process, creates generally applicable solution methods for illuminating steady-state spatial externality relationships for other spatial-dynamic diffusion resource management issues. By linking a confined aquifer and its unconfined recharge region with a dynamic boundary condition neglected in the economics literature, we introduce the physical realities that generate spatial externalities in all renewable confined aquifers. We derive spatial-dynamic first-order conditions for optimal extraction and characterize the policy relevant spatial-dynamic pumping cost and seawater intrusion cost externalities with hydrological assumptions appropriate to the different dynamic timescales of system components and the focus on seawater intrusion. For confined aquifers, we prove the marginal seawater intrusion cost externality decreases linearly in distance from the coast. Moreover, we demonstrate that the marginal seawater intrusion cost externality generally exceeds marginal pumping costs near the coast, implying substantial divergence between optimal and common property extraction near the coast, and significant divergence may extend to the inland aquifer boundary depending on both the magnitude and shape of the revenue function relative to extraction costs and aquifer parameters.     

THE EXISTENCE OF EQUILIBRIUM IN A DIFFERENTIATED DUOPOLY WITH NETWORK EXTERNALITIES*

The existence of a pure‐strategy subgame‐perfect equilibrium in qualities and prices is investigated in a duopoly model of vertical differentiation where quality improvements require a quadratic variable cost and network externalities operate. We show that there exists a parameter region where the incentive to predate at the quality stage prevents firms from reaching a pure‐strategy non‐cooperative equilibrium with prices above marginal costs. If network externalities are sufficiently large, a Bertrand equilibrium with zero profits may arise, although the amount of product differentiation is strictly positive.     

Do Currency Unions Grow Too Large For Their Own Good?

This article puts a rigorous foundation under the proposition that currency areas, as they admit more members, face a rising marginal cost curve which cuts the marginal benefit curve from below. However, at any given time, the median member faces lower marginal cost than the average member, so that, if new members are admitted by majority vote, and existing members are myopic, the currency area will expand beyond its optimum size. Although the currency area imposes negative externalities on countries outside it, we find that the existence of one currency union has no effect on the costs or benefits of forming or enlarging another.     

Integrating Tax Distortions and Externality Theory

Tax distortions are interpreted as fiscal externalities. By purchasing a taxed commodity, the individual generates tax revenue that is a benefit external to the purchaser. Behaving noncooperatively, the individual chooses a quantity that is less than the efficient level. The excess burden is interpreted as the benefit of choosing quantities cooperatively. The analysis clarifies the difference between the marginal cost of funds and the marginal excess burden, and explains the presence of compensated demands in the Harberger Triangle, in the Index of Discouragement, and in the Ramsey Equations.     

Monetary valuation of aircraft noise: A hedonic analysis around Amsterdam airport

In densely-populated countries and in particular in large metropolitan areas, the presence of so much human activity causes all sorts of negative externalities, for example traffic noise disturbance. These externalities call for corrective measures by the government. Economists have developed a number of procedures that provide reasonable estimates on the monetary value of some amenities and externalities. In this paper we develop a spatially-explicit hedonic pricing model for house prices in order to quantify the social cost of aircraft noise disturbance in monetary terms. While focusing on aircraft noise around Amsterdam airport in the urban fringe of the Amsterdam region, a key point in our analysis is that we account for background noise. We do this by taking multiple sources of traffic noise (i.e. road, railway and aircraft noise) into account simultaneously and by setting threshold values for all three sources of noise above which sound is generally experienced as nuisance. Based on our regression results we conclude that a higher noise level means ceteris paribus a lower house price. Air traffic has the largest price impact, followed by railway traffic and road traffic. These model outcomes can subsequently be used to estimate the marginal and total benefits of aircraft noise reduction in the studied area around Amsterdam airport. We find a marginal benefit of 1 dB noise reduction of 1459 Euro per house, leading to a total benefit of 1 dB noise reduction of 574 million Euros.     

我国渔业补贴政策及其改革探索

我国的渔业补贴政策在一定程度上是积极有效的,但同时也存在补贴总量不足、渔业补贴结构不合理、补贴种类不齐全和补贴核算指标体系不规范等问题。针对存在的问题,我国应从补贴结构、补贴种类和核算方法三个方面对渔业补贴予以改进：从SCM协定中渔业补贴分类、产业结构和补贴方式三方面调整渔业补贴结构;从逐渐削减渔船燃油补贴、加大远洋渔业补贴、新增休闲渔业补贴、建立政府支持型渔业保险制度等方面调整渔业补贴种类;把生产者补贴等值法（PSE）作为渔业补贴核算方法。     

生态渔业的主要模式

本文在对生态渔业概念界定的基础上,运用实证研究与规范研究相结合的方法,对我国发展生态渔业的必要性和可行性进行了,在此基础上指出,生态渔业应当成为我国实现渔业可持续发展的主要模式,为了发展生态渔业,应对目前生态渔业尚存在的若干问题进行研究,并采取制度创等对策。