Back to the future: A retrospective assessment of model‐based scenarios for the management of the shrimp fishery in French Guiana facing global change

While the number of models dedicated to predicting the consequences of alternative resource management strategies has increased, instances in which authors look back at past predictions to learn from discrepancies between these and observed developments are scarce. In the past decades, the French Guiana shrimp fishery has experienced shrimp market globalization and decreasing levels of shrimp recruitment due to environmental changes. In 2006, a bio‐economic model of this fishery was developed to simulate its possible responses to economic and environmental scenarios up to 2016. Here, we compare here these predictions to the observed trajectories. While the number of active vessels corresponds to that which was predicted, the estimated shrimp stock does not. Important driving factors had not been anticipated, including a general strike, natural disasters, and the end of the global financial crisis. These results show the importance of participative approaches involving stakeholders in the co‐construction and shared representation of scenarios. Recommendations for resource managers

• Effective fisheries resources management and a fortiori, the capacity of the fisheries to adapt to global change, requires understanding of both ecological and economics dynamics.
• The temporal trajectory of the trawling shrimp fisheries has been well monitored, and the decline of both stock and fleet is understood regarding ecological and economic changes: Changes in the environmental conditions of shrimp recruitment, and oil price increase and selling price decrease.
• However, our bio‐economic modeling work showed that, even with a good understanding of the dynamics explaining past trajectories, unpredictable events (strike, natural disasters…) have acted as other key driving factors altering the capacity of the model to represent possible futures.
• These results led us to recommend a better integration of the expertise of social and political scientists in developing models of bio‐economic systems to increase the quality of scenario predictions, and to argue for more participative approaches involving the stakeholders.

     

A MODEL FOR THE BIOECONOMIC EVALUATION OF MARINE PROTECTED AREA SIZE AND PLACEMENT IN THE NORTH SEA

ABSTRACT. The use of marine protected areas (MPAs) as a basic management tool to limit exploitation rates in marine fisheries has been widely suggested. Models are important in predicting the consequences of management decisions and the design of monitoring programs in terms of policy goals. However, few tools are available that consider both multiple fleets and ecosystem scale dynamics. We use a new applied game theory tool, Ecoseed, that operates within a temporally and spatially explicit biomass dynamics model, Ecopath with Ecosim, to evaluate the efficacy of marine protected areas in the North Sea in both ecological and economic terms. The Ecoseed model builds MPAs based on the change in values of predicted economic rents of fisheries and the existence value of biomass pools in the ecosystem. We consider the market values of four fisheries operating in the North Sea: a trawl fishery, a gill net fishery, a seine fishery, and an industrial (reduction) fishery. We apply existence values, scaled such that their aggregate is similar to the total fishery value, to six biomass pools of concern: juvenile cod, haddock, whiting, saithe, seals, and the collective pool ‘Other predators’ that include marine mammals. Four policy options were considered: to maximize the rent only; to maximize the existence values only; to maximize the sum of the rent and existence values; and, finally, to maximize the sum of the rent and the existence values, but excluding only the trawl fleet from the MPA. The Ecoseed model suggests that policy goals that do not include ecological considerations can negatively impact the rents obtained by the different fishing sectors. The existence values will also be negatively impacted unless the MPA is very large. The Ecoseed model also suggests that policy goals based solely on existence values will negatively impact most fisheries. Under policy options that included ecological considerations, maximum benefits were derived from an MPA that covered 25–40% of the North Sea, placed along the southern and eastern coasts. Finally, the Ecoseed model suggests that an exclusion of the trawl fishery only from the MPA can provide small‐to‐substantial positive impacts to most species and fleets; this relative impact depends on level of interaction between the trawl fleet and the other fleets target species (e.g., through bycatch).     

REBUILDING THE EASTERN BALTIC COD STOCK UNDER ENVIRONMENTAL CHANGE–A PRELIMINARY APPROACH USING STOCK,ENVIRONMENTAL, AND MANAGEMENT CONSTRAINTS

ABSTRACT. . The population dynamics of the Eastern Baltic cod (Gadus morhua callarias L.), unlike many other stocks, shows a strong dependency on environmental conditions. To test the implications of different management policies on the stock and the fishery in a system of global environmental change, we apply a spatially disaggregated, discrete time, age‐structured model of the Eastern Baltic cod stock in 50 year simulation analyses. The simulation provides an analysis of stock, yield, and revenue development under various management policies and environmental scenarios. The policy analysis, focusing on different regulations of fishing mortality, is embedded into three environmental scenarios, assuming low, medium, or high climate and environmental change. The environmental assumptions are based on simulation results from a coupled atmosphere‐ocean regional climate model, which project salinity in the Baltic Sea to decrease by 7–47% in the period 2071–2100 relative to the reference period 1961 1990. Our simulation results show that a significant reduction in fishing mortality is necessary for achieving high long‐term economic yields. Moreover, under the environmental scenarios presented, a stock collapse cannot be prevented. It can, however, be postponed by the establishment of a marine reserve in ICES subdivision 25.     

CLIMATE CHANGE AND FISHERIES: ASSESSING THE ECONOMIC IMPACT IN ICELAND AND GREENLAND

ABSTRACT. . Climate changes in the 21st century are expected to significantly increase ocean temperatures and modify other oceanographic conditions in the North Atlantic. Marine biological research suggests that the impacts on the commercially most important fish stocks in the Icelandic‐Greenland ecosystem may well be quite substantial. This will obviously lead to a corresponding impact on the economies of these two countries. However, the timing, extent and biological impact of global warming is quite uncertain. As a result the economic impact is similarly uncertain. This paper attempts to provide estimates of the impact of altered fish stocks due to global warming on the Icelandic and Greenland economies. The approach is one of stochastic simulations. This involves essentially three steps. The first is to obtain predictions of the impact of global warming on fish stocks and the associated probability distribution. For this we rely on recent marine biological predictions. The second step is to estimate the role of the fisheries sector in the two economies. This is done with the help of modern econometric techniques based on economic growth theory and historical data. Obviously these estimates are also subject to stochastic errors and uncertainty. The third step is to carry out Monte Carlo simulations on the basis of the above model and the associated uncertainties. The result of the Monte Carlo simulations consists of a set of dynamic paths for GDP over time with an expected value and a probability distribution for each future year. On this basis it is possible to calculate confidence intervals for the most likely path of GDP over time. The results indicate that the fisheries impact of global warming on the Icelandic GDP is more likely to be positive than negative but unlikely to be of significant magnitude compared to historical economic growth rates and fluctuations. The uncertainty of this prediction, however, is large. For Greenland, the impact on fish stocks and the GDP is highly likely to be positive and quite substantial relative to the current GDP. Due to less knowledge of the relationship between the fisheries sector and the Greenland economy, however, the confidence interval of this prediction is even wider than in the case of Iceland.     

MEASURING PRODUCTIVITY AND ITS COMPONENTS FOR FISHERIES: THE CASE OF THE ALASKAN POLLOCK FISHERY, 1994–2003

Abstract Traditional productivity measures have been much less prevalent in fisheries economics than other measures of economic and biological performance. It has been increasingly recognized, however, that modeling and measuring fisheries' production relationships is central to understanding and ultimately correcting the repercussions of externalities and poorly designed regulations. We use a transformation function production model to estimate productivity and its components for catcher–processors in the Bering Sea and Aleutian Islands pollock fishery, before and after the introduction of a cooperative system that grants exclusive harvesting privileges and allows quota exchange. We also recognize the roles of externalities from pollock harvesting by incorporating data on climate, bycatch, and fish biomass. We find that productivity has been increasing over time, that many productive contributions and interactions of climate, bycatch, and fishing strategies are statistically significant, and that regulatory changes have had both direct and indirect impacts on catch patterns and productivity.     

FEATURES OF BIOECONOMICS MODELS FOR THE OPTIMAL MANAGEMENT OF A FISHERY EXPLOITED BY TWO DIFFERENT FLEETS

ABSTRACT. After the extension of the Exclusive Economic Zone, in 1977, to 200 miles, most fish stocks came under jurisdiction of the adjacent coastal states. This development opened prospects of effective management of the open sea fisheries. Coastal states have the right to plan out the operation of so-called by Clarke and Munro “distant water fishing nations” from their Exclusive Economic Zone. Under some arrangements, a foreign fleet is allowed to harvest the resource in the Exclusive Economic Zone area. Clarke and Munro, in [1987] and [1991], focus on the issue of optimum terms and conditions of access and, in doing so, built a multiobjective model. The main goal of the present work is the development of a more general model including more variables and parameters related to the presence of a domestic fleet as well as a distant water fishing nation. The main difficulty resides in sharing the harvesting between the two fleets. The study responds to the realistic problemof coastal states who own enough resource stocks to allow harvesting by several kinds of fleets. Two optimal scenarios are developed, in each of them a solution is given.     

DEA-based predictors for estimating fleet size changes when modelling the introduction of rights-based management

The introduction of individual transferable quotas (ITQs) into a fishery is going to change not only the amount of catch a fleet can take, but often also changes the fleet structure, particularly if total allowable catches are decreased. This can have an impact on the economic, social and environmental outcomes of fisheries management. Management Strategy Evaluation (MSE) modelling approaches are recognised as the most appropriate method for assessing impacts of management, but these require information as to how fleets may change under different management systems. In this study, we test the applicability of data envelopment analysis (DEA) based performance measures as predictors of how a fishing fleet might change under the introduction of ITQs and also at different levels of quota. In particular, we test the assumption that technical efficiency and capacity utilisation are suitable predictors of which boats are likely to exit the fishery. We also consider scale efficiency as an alternative predictor. We apply the analysis to the Torres Strait tropical rock lobster fishery that is transitioning to an ITQ-based management system for one sector of the fishery. The results indicate that capacity utilisation, technical efficiency and scale efficiency are reasonable indicators of who may remain in the fishery post ITQs. We find that the use of these measures to estimate the impacts of lower quota levels provides consistent fleet size estimates at the aggregate level, but which individual vessels are predicted to exit is dependent on the measure used.     

Regional economic impacts of fish resources utilization from the Barents Sea: Trade-offs between economic rent,employment and income

A multi-objective programming model has been developed to investigate the trade-offs among regional employment, regional income, and economic rent of the North Norwegian cod fisheries in the Barents Sea, where all vessels are regulated by an individual quota system. Fishery managers are confronted with the problem on how best to allocate the total allowable catch (TAC) among four vessel groups. It is apparent that depending on how fishery managers view the importance of each objective, the desirable allocation of TAC will differ. Therefore, the trade-offs information can be very useful to fishery managers indicating the relative “expensiveness” of trading one objective with another. Decision maps are generated depicting how the trade-offs between two objectives are affected by the third objective. Compromise solutions taking into account all three objectives will allocate the TAC to satisfy the maximum capacity of both the factory trawlers and the small-scale vessels with the remaining TAC distributed to the coastal fleet and fresh fish trawlers.     

MODELING CLIMATE CHANGE AND THE EFFECT ON THE NORWEGIAN SALMON FARMING INDUSTRY

Abstract Global warming is expected to affect the ecosystem in the Northeast Atlantic, and substantial changes will also affect the aquaculture industry. Farming of salmon and trout is the biggest aquaculture industry in Norway, with an export value of about 3 billion US dollars in 2007. The objective of the paper is to analyze the potential economic effect a general increase in sea temperature can have on the Norwegian salmon aquaculture industry. The assessment of the economic impact of global warming is made possible by estimating a growth function, which explicitly includes sea water temperature. The analysis compares the economic effect of a climate change on fish farming plants in the south and the north of Norway. The scenarios are based on a model with monthly seasonal variation in temperature.     

ON THE ECONOMICS OF BIOLOGICAL INVASION: AN APPLICATION TO RECREATIONAL FISHING

Abstract The paper demonstrates four general mechanisms that may affect economically valuable species when exposed to biological invasion. We distinguish between an ecological level effect and an ecological growth effect. In addition, we present an economic quantity effect working through demand. Finally, we suggest that there is an economic quality effect that reflects the possibility that invasions affect the harvesting agents directly through demand‐side forces. For example, this may occur because the state of the original species or the ecosystem is altered. We depart from the existing literature by revealing ecological and economic forces that explain why different agents may lack incentives to control invasions. The theoretical model is illustrated by the case where escaped farmed salmon (EFS) influence wild Atlantic salmon fisheries.     

AN INDICATOR FOR ECOSYSTEM EXTERNALITIES IN FISHING

Ecosystem externalities arise when one use of an ecosystem affects its other uses through the production functions of the ecosystem. We use simulations with a size‐spectrum ecosystem model to investigate the ecosystem externality created by fishing of multiple species. The model is based upon general ecological principles and is calibrated to the North Sea. Two fleets are considered: a “forage fish” fleet targeting species that mature at small sizes and a “large fish” fleet targeting large piscivorous species. Based on the marginal analysis of the present value of the rent, we develop a benefit indicator that explicitly divides the consequences of fishing into internal and external benefits. This analysis demonstrates that the forage fish fleet has a notable economic impact on the large fish fleet, but the reverse is not true. The impact can be either negative or positive, which entails that for optimal economic exploitation, the forage fishery has to be adjusted according to the large fish fishery. With the present large fish fishery in the North Sea, the two fisheries are well adjusted; however, the present combined exploitation level is too high to achieve optimal economic rents.     

Resource allocation in the North Sea demersal fisheries: A goal programming approach

The management of a fishery is a complex task generally involving multiple, often conflicting, objectives. These objectives typically include economic, biological and social goals such as improving the income of fishers, reducing the catch of depleted species and maintaining employment.Multicriteria decision making (MCDM) techniques appear wellsuited to such a management problem, allowing compromises between conflicting objectives to be analysed in a structured framework. In comparison to other fields, such as water resource planning, forestry and agriculture, there have been few applications of MCDM to fisheries.In this paper, a goal programming model of the North Sea demersal fishery is presented. The model is used to demonstrate the potential applicability of this type of approach to the analysis and development of fisheries management plans with multiple objectives. Alternative scenarios are considered for the problem, and tradeoffs between given objectives are also highlighted and discussed.     

MODELING THE GLOBAL FISHMEAL AND FISH OIL MARKETS

Abstract To explore the drivers of change in the complex system relating small pelagic fisheries and fishmeal/fish oil markets, to identify the interactions between these drivers and their overall impacts, we propose a bio‐economic model, coupling the ecological and the economic dynamics of these global commodities. The model enables an analysis of the consequences of both global and local changes in the environment of production systems. Through sensitivity analysis of specific input parameters, we evaluate the robustness of the overall system to such changes and show that local responses of production systems and markets cannot be considered in isolation from the set of interactions at global level.     

THE PROBLEM OF NONMALLEABLE CAPITAL REVISITED; A STUDY OF THE PACIFIC HALIBUT FISHERY

It has been suggested in the literature on commercial fisheries that fishing capital may be nonmalleable, i.e., not easily moved from one fleet to another, and that the socially optimal rate of capitalization of boats may depend on the degree of malleability (irreversibility) of the fishing fleet. To find out how irreversibility affects optimal regulation, two of the many possible regulatory tools, unallocated quotas and catch taxes, are examined. These optimal policies are derived, alternatively assuming malleable and nonmalleable fishing capital. Using a simulation of the Pacific halibut fishery, the results obtainable through catch quotas are shown to be inferior to those obtainable through taxes, but that the degree of malleability of capital has a surprisingly small impact on policy. A sensitivity analysis is performed, rerunning these simulations over a variety of parameter values. The previous results are largely borne out.     

THE OPTIMAL MANAGEMENT OF TRANSBOUNDARY FISHERIES: GAME THEORETIC CONSIDERATIONS

One of the most ubiquitous of the fishery management problems to have arisen as a result of E.F.J. is that of managing transboundary resources. Economic analysis of this problem rests upon models blending the standard dynamic economic analysis of fisheries with game theory. The analysis reveals that noncooperation is likely to have severe economic consequences and that cooperative arrangements must deal with possible conflicting goals of management, as well as the division of economic returns from the fishery. While the existing economic analysis of transboundary fishery management is far from complete, it can be shown that the analysis is capable of providing important insights into existing real world cases of transboundary resource management.     

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.     

THE ENSEMBLE KALMAN FILTER FOR MULTIDIMENSIONAL BIOECONOMIC MODELS

To integrate economic considerations into management decisions in ecosystem frameworks, we need to build models that capture observed system dynamics and incorporate existing knowledge of ecosystems, while at the same time accommodating economic analysis. The main constraint for models to serve in economic analysis is dimensionality. In addition, to apply in long‐term management analysis, models should be stable in terms of adjustments to new observations. We use the ensemble Kalman filter to fit relatively simple models to ecosystem or foodweb data and estimate parameters that are stable over the observed variability in the data. The filter also provides a lower bound on the noise terms that a stochastic analysis requires. In this paper, we apply the filter to model the main interactions in the Barents Sea ecosystem. In a comparison, our method outperforms a regression‐based approach.     

THE VALUE OF SHORT‐RUN CLIMATE FORECASTS IN MANAGING THE COASTAL COHO SALMON (ONCORHYNCHUS KISUTCH) FISHERY IN WASHINGTON STATE

ABSTRACT. . In recent years our understanding of the intricate connections between climate variability, marine and freshwater environmental conditions and the responses of fish stocks has improved considerably. With predictable relationships between the environment and stock abundance, fishery managers should be able to forecast variation in stock survival and recruitment. Such forecasts present an opportunity for increasing the economic value of fisheries and for achieving other management objectives, such as stock conservation and maintenance of population diversity. After describing a 4‐step framework for addressing the question ‘What is a forecast worth?’ in a fishery decision‐making context, we introduce the management system for Washington's coastal coho salmon (Oncorhynchus kisutch) fishery. Then we apply the 4‐step framework to estimate the value of improved run size forecasts in the annual harvest management of coho salmon in Washington State. Our principal analytical tool is a stochastic simulation model that incorporates the main characteristics of the fishery. The paper concludes with a discussion of opportunities and constraints to the use of climate‐based forecasts in fishery management on various spatial and temporal scales, and we consider the challenges associated with forecasting variations in fish stock size caused by shifts in climate and related ocean conditions.     

A mixed integer programming model of a multicohort single-species fishery

Many marine fisheries are under pressure from overfishing. Fisheriesmanagement is a complex process because of the need to considerthe interaction of the biological components of the fishery,the technical characteristics of the fishing fleet, and theeconomic aspects of the fishing industry. In this paper, a mixedinteger programming (MIP) model for determining the policy tomaximize the long-run economic benefit from a single-speciesmulticohort fishery is developed. The model takes account ofthe biological, technical, and economic characteristics of thefishery, using integer variables to model the fishing activities.An iterative procedure for solving the model using commercialMIP software is described, and the viability of this procedureis illustrated using data for the western mackerel fishery.     

REBUILDING THE EASTERN BALTIC COD STOCK UNDER ENVIRONMENTAL CHANGE (PART II): TAKING INTO ACCOUNT THE COSTS OF A MARINE PROTECTED AREA

Abstract This study adds a cost analysis of the Eastern Baltic cod fishery to the existing model presented in Röckmann et al. [2007a] . As cost data on this international fishery do not exist, data from Denmark are extrapolated to the whole international fishery. Additionally, unit and total variable costs are simulated, and the sensitivity to a set of different cost–stock and cost–output elasticities is tested. The study supports preliminary conclusions that a temporary marine reserve policy, which focuses on protecting the Eastern Baltic cod spawning stock in the International Council for the Exploration of the Sea (ICES) subdivision 25, is a valuable fisheries management tool to (i) rebuild the overexploited Eastern Baltic cod stock and (ii) increase operating profits. The negative effects of climate change can be postponed for at least 20 years—depending on the assumed rate of future climate change. Including costs in the economic analysis does not change the ranking of management policies as proposed in the previous study where costs were neglected.