The costs and benefits of animal predation: An analysis of Scandinavian wolf re-colonization.

After coming close to extinction, the grey wolf (Canis lupus) has re-colonized Scandinavia during the last two decades. The current population numbers some 100–120 individuals, and is distributed in small packs along the Swedish–Norwegian border. However, with wolf re-colonization, several conflicts have arisen. One conflict is due to wolf predation on livestock, especially sheep and reindeer. Another is predation on wild ungulates. As the wolves have shown a strong preference for moose (Alces alces) in this respect, a smaller moose population is available for game hunting. The cost of increased moose predation by wolves is examined using a two-step process. First, we analyse the costs to landowners, comprising the loss of animals potentially available for hunting less the reduction in browsing damage associated with a smaller moose population. Second, we examine the problem from a broader point of view, where costs external to landowners and local communities are included. By far the most important cost here is damage related to collisions between moose and motor vehicles.

The maximum economic yield management of an age-structured salmon population

This chapter develops a sustainable economic yield harvesting model for the wild Atlantic salmon (Salmo salar) where the population comprises different age classes. It is shown that the weight–fecundity relationship of the spawning population, comprising two age classes, is crucial for the maximum sustainable yield fishing composition. In a next step the optimal selective fishing is replaced by an optimal non-selective fishing pattern, and the discrepancy between these two schemes is analyzed.

Economic modeling approaches for wildlife and species conservation

This paper presents modeling approaches for wildlife and species conservation with a special emphasis on large mammals in a developing country setting. In such countries there are frequently conflicts over land use and species conservation, and institutions for managing conflicts are often weak or even lacking. In addition, most of the world species and biodiversity are found in developing countries. Two main issues are discussed. First, we study a situation where the wildlife is valuable, but is considered a pest by the local people living close to the wildlife. Second, we consider models with a discrepancy between management geography and biological geography, and where the species flows between a conservation area with no harvesting and a neighboring area with harvesting and possible habitat degradation.

Modern fishing technology and profitability in a second best situation

This paper formulates a simple biomass growth model of a fishery. In this model, fish are exploited in a restricted open-access regime where a fixed number of harvesters exploit the fish stock in a myopic profit-maximizing manner. It is demonstrated that more modern fishing technology has a two-sided profitability effect, where the direct, short-run, positive effect is counterbalanced by a negative, long-run, indirect effect that slows population growth. In the steady state, it is shown that more modern technology dissipates the rent under already high exploitation pressure, while the opposite occurs if the fish stock is initially little, or moderately, exploited.Fisheries; technology; rent; second best

Marine reserves. A bio-economic model with asymmetric density dependent migration

A static bioeconomic model of a marine reserve allowing asymmetric density dependent migration between the reserve and the fishable area is introduced. This opens for habitat or ecosystem differences allowing different fish densities within and outside a reserve, not described in earlier studies. Four management scenarios are studied; a) maximum harvest, b) maximum current profit, c) open access and d) maximum sustainable yield (MSY) in the reserve. These are all analysed within the Induced Sustainable Yield Function (ISYF), giving the relationship between the fish abundance inside the reserve and the harvesting taking place outside. A numerical analysis shows that management focused on ensuring MSY within the reserve under the assumption of symmetric migration may be negative from an economic point of view, when the area outside the reserve is detrimental compared to the reserve. Furthermore, choice of management option may also have negative consequences for long run resource use if it is incorrectly assumed that density dependent migration is symmetric. The analysis also shows that the optimal area to close, either a more or a less attractive ecosystem for the resource in question, may differ depending on the management goal.bioeconomics; marine reserves; migration; management

Restoring a Fish Stock: A Dynamic Bankruptcy Problem

Total Allowable Catch (TAC) regulating schemes have been introduced in most fisheries. TAC distribution following the Proportional Rule, based on historical catches, implies that harvesters or vessel groups which have captured more in the past and contributed to overfishing are getting larger quotas than groups that have contributed less to overfishing. In contrast to this rule a more egalitarian rule, the Constrained Equal Award Rule, is proposed for distributing the TAC. Contingent upon the fishing techniques used by the harvesters, it is demonstrated how the fish stock recovery period, harvest and profitability may vary according to these two rules.

Conservation of wildlife. A bio-economic model of a wildlife reserve under the pressure of habitat destruction and harvesting outside the reserve.

Biodiversity is today threatened by many factors of which destruction and reduction of habitats are considered most important for terrestrial species. One way to counteract these threats is to establish reserves with restrictions on land-use and exploitation. However, very few reserves can be considered islands, wildlife species roam over large expanses, often via some density dependent dispersal process. As a consequence, habitat destruction, and exploitation, taking place outside will influence the species abundance inside the conservation area. The paper presents a theoretical model for analysing this type of management problem. The model presented allows for both the common symmetric dispersal as well as what is called asymmetric dispersal between reserve and outside area. The main finding is that habitat destruction outside may not necessarily have negative impact upon the species abundance in the reserve. As a consequence, economic forces working in the direction of reducing the surrounding habitat have unclear effects on the species abundance within the protected area. We also find that harvesting outside the reserve may have quite modest effect on the species abundance in the reserve. This underlines the attractiveness of reserves from a conservation viewpoint.

The economics of a stage-structured wildlife population model

A four-stage model (calves, yearlings, adult female and adult male) of the Scandinavian moose (Alces alces) is formulated. Fecundity is density dependent while mortality is density independent. The paper aims to demonstrate the economic content of such a wildlife model and how this content may change under shifting economic and ecological conditions. Two different harvesting regimes are explored: hunting for meat, and trophy hunting. It is shown how different ways to compose the harvest influences the profitability while, at the same time, the population levels of the different stages may only change modestly. It is also shown why different market situations require different compositions of the harvest, knowledge that is disregarded in the traditional bioeconomic modelling approach.wildlife; harvesting; trophy hunting

On the management of interconnected wildlife populations

Economic interdependency of wildlife or fish stocks is usually attributed to ecological interdependency, such as predator - prey and competitive relationships, or to density dependent migration of species between different areas. This paper provides another channel for economic interdependency of wildlife where density independent migration and market price interaction affect the management strategies among different landowners. Management is studied under three market conditions for selling hunting licences: price taking behaviour, monopoly market and duopoly market. Harvesting of the Scandinavian moose is used as an example. The paper provides several results on how economic interdependency works through the migration pattern. When a duopoly market is introduced, hunting license price interaction among the landowners plays an additional role in determining the optimal harvesting strategy.

Livestock as insurance and social status. Evidence from reindeer herding in Norway

The theory of livestock as a buffer stock predicts that agropastoralists facing substantial risks typically will use liquid assets, such as livestock, for self-insurance to smooth consumption. This paper examines this hypothesis for reindeer herders in Norway where the herders, in contrast to pastoralists in, say, Sub-Saharan Africa, face well functioning credit markets. Using survey data including slaughtering responses to a hypothetical meat price increase, we test whether keeping reindeer as insurance against risks affects the slaughter response. Furthermore, we study whether status motives for keeping large herds affect the harvest response to a changing slaughter price. As a background for the empirical analysis, a stochastic bioeconomic model describing Saami reindeer herding is formulated