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 predator–prey 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 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 meaningful defined without setting strategic goals at the ecosystem level for functional groups.

Intertemporal Choice of Marine Ecosystem Exploitation

The term “Fishing Down Marine FoodWebs” 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 predator–prey interaction, the inclusion of mass balance in the predator–prey allocation, and mortality and somatic growth as consequences of the predator–prey 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 management’s 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.

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

Mussel production and Water Framework Directive targets in the Limfjord, Denmark: an integrated assessment for use in system-based management

Growth of human activities often conflict with nature conservation requirements and integrated assessments are necessary to build reliable scenarios for management. In the Limfjord, Denmark's largest estuary, nutrient loading reductions are necessary to fulfill EU regulations criteria, such as the Water Framework Directive (WFD). Cuts in nutrient loadings do not necessarily result in corresponding reductions in eutrophication impacts or in improving primary and higher trophic-level production. Similarly, the socioeconomic consequences of a mussel fishery and aquaculture production are complex and hard to predict. This study focuses on the usefulness of a System Approach Framework (SAF) implementation for stakeholder understanding of complex systems and development of sustainable management. Ecological-social-economic (ESE) model simulations clearly demonstrated the potential problems of WFD implementation for mussel fishers and mussel farmers. Simulation of mussel fishery closures resulted in a tenfold increase in the hitherto fishable mussel biomass and a similar decrease in the biomass of shallow-water mussels and medium-sized ones in deep water. A total closure of the mussel fishery could result in an annual profit loss of ~6.2 million. Scenario simulation of the introduction of one, two, three, and four mussel culture farms of ~19 ha showed that the introduction of line-mussels would decrease the biomass of wild mussels both in shallow and deep waters, affecting the catch and profit of fishers. The SAF, which included consultation with stakeholders at all stages, differs from the traditional public consultation process in that (1) communication was verbal and multilateral, (2) discussion among stakeholders was facilitated, and (3) stakeholder opinions and priorities formed the focus of the ESE assessment

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