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

Scientific mindfulness: a foundation for future themes in international business

We conceptualize new ways to qualify what themes should dominate the future IB research agenda by examining three questions: Whom should we ask? What should we ask and which selection criteria should we apply? What are the contextual forces? We propose scientific mindfulness as the way forward for generating themes in IB research

Behavioral Response of a Mobile Marine Predator to Environmental Variables Differs Across Ecoregions

Animal movement and habitat selection are in part a response to landscape heterogeneity. Many studies of movement and habitat selection necessarily use environmental covariates that are readily available over large‐scales, which are assumed representative of functional habitat features such as resource availability. For widely distributed species, response to such covariates may not be consistent across ecosystems, as response to any specific covariate is driven by its biological relevance within the context of each ecosystem. Thus, the study of any widely distributed species within a limited geographic region may provide inferences that are not widely generalizable. Our goal was to evaluate the response of a marine predator to a suite of environmental covariates across a wide ecological gradient. We identified two behavioral states (resident and transient) in the movements of shortfin mako sharks (Isurus oxyrinchus) tracked via satellite telemetry in two regions of the western North Atlantic Ocean: the tropical Caribbean/Gulf of Mexico marginal sea (CGM), and the temperate waters off the east coast of North America (OWA). We compared patterns of resident behavior between regions, and modeled relationships between oceanographic variables and resident behavior. We tracked 39 sharks during 2013 – 2015. Resident behavior was associated with shallow, continental shelf and slope waters in both regions. In the OWA resident behavior was associated with low sea surface temperature and high primary productivity, however, sharks exhibited no response to either variable in the CGM. There was a negative relationship between sea‐surface height gradient (a proxy for oceanic fronts) and resident behavior in the OWA, and a positive relationship in the CGM. Our observations likely reflect shark responses to regional variability in factors responsible for the distribution and availability of prey. Our study illustrates the importance of studying widely distributed species in a consistent manner over large spatial scales

An argument for the use of Aristotelian method in bioethics

The main claim of this paper is that the method outlined and used in Aristotle's Ethics is an appropriate and credible one to use in bioethics. Here “appropriate” means that the method is capable of establishing claims and developing concepts in bioethics and “credible” that the method has some plausibility, it is not open to obvious and immediate objection. It begins by suggesting why this claim matters and then gives a brief outline of Aristotle's method. The main argument is made in three stages. First, it is argued that Aristotelian method is credible because it compares favourably with alternatives. In this section it is shown that Aristotelian method is not vulnerable to criticisms that are made both of methods that give a primary place to moral theory (such as utilitarianism) and those that eschew moral theory (such as casuistry and social science approaches). As such, it compares favourably with these other approaches that are vulnerable to at least some of these criticisms. Second, the appropriateness of Aristotelian method is indicated through outlining how it would deal with a particular case. Finally, it is argued that the success of Aristotle's philosophy is suggestive of both the credibility and appropriateness of his method.</p

A comparison of the seasonal movements of tiger sharks and green turtles provides insight into their predator-prey relationship

During the reproductive season, sea turtles use a restricted area in the vicinity of their nesting beaches, making them vulnerable to predation. At Raine Island (Australia), the highest density green turtle Chelonia mydas rookery in the world, tiger sharks Galeocerdo cuvier have been observed to feed on green turtles, and it has been suggested that they may specialise on such air-breathing prey. However there is little information with which to examine this hypothesis. We compared the spatial and temporal components of movement behaviour of these two potentially interacting species in order to provide insight into the predator-prey relationship. Specifically, we tested the hypothesis that tiger shark movements are more concentrated at Raine Island during the green turtle nesting season than outside the turtle nesting season when turtles are not concentrated at Raine Island. Turtles showed area-restricted search behaviour around Raine Island for ~3&ndash;4 months during the nesting period (November&ndash;February). This was followed by direct movement (transit) to putative foraging grounds mostly in the Torres Straight where they switched to area-restricted search mode again, and remained resident for the remainder of the deployment (53&ndash;304 days). In contrast, tiger sharks displayed high spatial and temporal variation in movement behaviour which was not closely linked to the movement behaviour of green turtles or recognised turtle foraging grounds. On average, tiger sharks were concentrated around Raine Island throughout the year. While information on diet is required to determine whether tiger sharks are turtle specialists our results support the hypothesis that they target this predictable and plentiful prey during turtle nesting season, but they might not focus on this less predictable food source outside the nesting season

Automated data analysis to rapidly derive and communicate ecological insights from satellite-tag data: A case study of reintroduced red kites

Analysis of satellite-telemetry data mostly occurs long after it has been collected, due to the time and effort needed to collate and interpret such material. Such delayed reporting does reduce the usefulness of such data for nature conservation when timely information about animal movements is required. To counter this problem we present a novel approach which combines automated analysis of satellite-telemetry data with rapid communication of insights derived from such data. A relatively simple algorithm (comprising speed of movement and turning angle calculated from fixes), allowed instantaneous detection of excursions away from settlement areas and automated calculation of home ranges on the remaining data Automating the detection of both excursions and home range calculations enabled us to disseminate ecological insights from satellite-tag data instantaneously through a dedicated web portal to inform conservationists and wider audiences. We recommend automated analysis, interpretation and communication of satellite tag and other ecological data to advance nature conservation research and practice