33 research outputs found
The Stock Concept Applicability for the Economic Evaluation of Marine Ecosystem Exploitation
Stock models, in which production is interpreted as if it were the population growth of a stock, have been the preferred tool for fishery economics since Clark and Munro (1975) introduced capital theory in these models. Ravn-Jonsen (2009c) applied capital theory to a model in which the production in the ecosystem is a consequence of predatorâprey interaction and the somatic growth of the predator as a result of this interaction. By deducing the results of Clark and Munro anew, the assumptions of the stock model are clarified. Four different biomass measures are introduced in the ecosystem model as stocks. The optimum point found with the stock model approach is compared with the optimum point found in the ecosystem model with the capital value calculations of the occurring rent flow. A comparison shows that the stock model fails to generate the correct optimal point. The assumptions behind the use of stock models for species population models are discussed. The population stock model corresponds to a holistic community view, which has in fact failed to explain various phenomena. The production of the marine ecosystem cannot be reduced to a model as if the production were a consequence of the growth of a stock. The concept of a stock is rather an illusion, as is the concept of an optimal stock level. It is essential to liberate fishery economics from a simplified view of population and communities.
Ecosystem Management a Management View
The need for management of the marine ecosystem using a broad perspective has been recommended under a variety of names. This paper uses the term Ecosystem Management, which is seen as a convergence between the ecological idea of an organisational hierarchy and the idea of strategic planning with a planning hierarchyâwith the ecosystem being the strategic planning level. Management planning requires, in order to establish a quantifiable means and ends chain, that the goals at the ecosystem level can be linked to operational levels; ecosystem properties must therefore be reducible to lower organisational levels. Emergence caused by constraints at both the component and system levels gives rise to phenomena that can create links between the ecosystem and operational levels. To create these links, the ecosystemâs functional elements must be grouped according to their functionality, ignoring any genetic relation. The population structure is below the ecosystem in terms of the planning level, and goals for the communityâs genetic structure cannot be meaningful defined without setting strategic goals at the ecosystem level for functional groups.
Intertemporal Choice of Marine Ecosystem Exploitation
The term âFishing Down Marine FoodWebsâ describes the gradual transition in landing from marine ecosystems towards organisms lower in the food web. To address this issue and the need to manage the marine ecosystem in a broader perspective, Ecosystem Management is recommended. Ecosystem Management, however, requires models that can link the ecosystem level to the operation level, so this paper examines an ecosystem production model and shows that it is suitable for applying ground rent theory. This model is the simplest possible that incorporates the principles of size as the main determinant of the predatorâprey interaction, the inclusion of mass balance in the predatorâprey allocation, and mortality and somatic growth as consequences of the predatorâprey allocation. The model needs to be parameterized for the specific ecosystem and the price and cost functions must be established empirically before drawing the conclusion that Fishing Down Marine Food Webs is economically detrimental can be established directly. Nevertheless, the model does reveal a need for intertemporal balance with respect to both fish size and harvest volume. These aspects are not addressed in any systematic way at the ecosystem level in the present management. Therefore, economic predictions for an ecosystem managed as a common pool resource must be that the exploitation probably are conducted at lower sized than optimum. In addition, given its population stock approach, the present management probably overlooks the ability of an ecosystem to sustain total volume of harvest. Given the two aspects of intertemporal choice revealed by the model, the conclusion must be that the Fishing Down Marine Food Webs is probably driven by the current managementâs inability to conduct adequate intertemporal balancing; therefore, it is probably detrimental from an economic point of view. The marine ecosystem therefore requires an ecosystem management for economic reasons; in this context, models like the one presented here can serve as useful planning tools.
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Ecosystem Management: A Management View
The need for management of the marine ecosystem using a broad perspective has been recommended under a variety of names. This paper uses the term Ecosystem Management, which is seen as a convergence between the ecological idea of an organisational hierarchy and the idea of strategic planning with a planning hierarchy - with the ecosystem being the strategic planning level. Management planning requires, in order to establish a quantifiable means and ends chain, that the goals at the ecosystem level can be linked to operational levels; ecosystem properties must therefore be reducible to lower organisational levels. Emergence caused by constraints at both the component and system levels gives rise to phenomena that can create links between the ecosystem and operational levels. To create these links, the ecosystem's functional elements must be grouped according to their functionality, ignoring any genetic relation. The population structure is below the ecosystem in terms of the planning level, and goals for the community's genetic structure cannot be meaningfully defined without setting strategic goals at the ecosystem level for functional groups
Cooperative Fisheries Outperform Non-cooperative Ones in the Baltic Sea Under Different Climate Scenarios
Game theory has been an effective tool to generate solutions for decision making in fisheries involving multiple countries and fleets. Here, we use a coupled bio-economic model based on a Baltic Sea dynamic multispecies food web model called BALMAR and, we compare non-cooperative (NC) and cooperative game (grand coalition: GC) solutions. Applications of game theory based on a food web model under climate change have not been studied before and the present study aims to fill this gap in the literature. The study focuses on the effects of climate variability on the biological, harvest and economic output of the game models by examining two different climate scenarios, a first scenario characterized by low temperature and high salinity and a second scenario by high temperature and low salinity. Our results showed that in the first scenario sprat spawning stock biomass (SSB) and harvest dropped dramatically both in the NC and the GC cases whereas, herring and cod SSBs and harvests were higher compared to a base scenario (BS) keeping temperature and salinity at mean historical levels. In the second scenario, the sprat SSB and the harvest was higher for both GC and NC cases while the cod and the herring SSBs and harvests were lower. The total GC payoffs clearly outperformed the NC payoffs across all scenarios. Likewise, the first and second scenario GC payoffs for countries were higher except for Poland. The findings suggested the climate vulnerability of Baltic Sea multi-species fisheries and these results would support future decision-making processes of Baltic Sea fisheries.Peer reviewe
Scenarios of ecological and economic consequences of rebuilding paths of depleted populations
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Valuing seafood attributes: stated choice model
This study applied brand choice model and stated preference data collected in French context by means of choice experiment to investigate value of intrinsic and extrinsic attributes of various fresh seafood species. The estimated models show that the extrinsic attributes (i.e. product forms, production method, and product origin) and intrinsic attributes (i.e. seafood species: salmon, cod, mussels, ect.) were significant determinants of consumer choice of seafood for their household consumption. Consumers assigned a significantly higher value for domestic and wild catch product. However, a deeper look into the market structure we revealed that only 39.5% of the sample is willing to pay a premium price for domestic and wild catch items in general. Salmon, cod, and saithe were evaluated relatively highest valued products while oyster, pangasius, and crab are lowest valued items. Market shares of the species in segments and entire market were predicted and appeared closely to actual market shares. The segment membership probability was estimated by the model and then regressed on demographic to give good suggestions for managers
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Market structure and segments for seafood: A stated preference approach
Demand structure and market segmentation for seafood have been investigated intensively. However, most the researches so far applied traditional demand analysis and descriptive segmentation approach by separated models. The traditional demand analysis assuming consumer homogeneity, behavior consistence, and using aggregate data may result biased estimation, while the segmentation based on descriptive approach has results less accessible and actionable. We the first used discrete choice model and stated preference data to simultaneously estimate the demand structure and segments for twelve seafood species in French context. The four-latent segments model have the best fit to the data and demand elasticities estimated are comparable to those in the traditional studies but provide more efficient and actionable guidance for practitioners. Consistence with previous seafood demand study we found that elasticities of high valued fish such as salmon, tuna, cod, sole, and shrimp are price elastic while low valued species like mussels, oyster, and pangasius are inelastic. Moreover, latent class model revealed that 39.5% of the sample are not price sensitive, 29.6% moderate sensitive, 20.3% sensitive, and 10.6% are very sensitive. Similarly, we investigated deeper for particular species and uncovered demand structure of each species. For instance, only 30.9% of consumers are price elastic for salmon, while 39.5% and 29.6% of the sample are inelastic and moderate elastic for this species, respectively. We also regressed the segment membership probabilities on the consumer characteristics to give better segment description and provide efficient guidance for seafood producers and marketers