Small-scale fisheries often operate under conditions of regulated open access; that is, the fishery is subject to natural or regulatory constraints on fishing technology, including regulations of fishing gear and fishing practices, but typically there is no direct regulation of catches. We study how an increase in harvesting efficiency changes the different components of welfare—consumer surplus and producer surplus—in such a regulated open-access fishery, taking t the feedback of harvesting on stock dynamics, i.e. the dynamic common-pool resource externality into account. We find that both components of welfare change in the same direction. If, and only if, initial efficiency is low enough so that there is no maximum sustainable yield (MSY) overfishing, an improvement of harvesting efficiency increases welfare.

In this paper a simple age-structured model is constructed to analyze how a wildlife population creating hunting value, but also damage costs, is influenced by predation. The model may exemplify a moose population causing forest browsing damage and exposed for predation by wolf or other big carnivores within a Scandinavian institutional setting. However, it can also fit to other ecological and institutional settings as in North America and other parts of Europe. Two age classes of the prey population, immature and mature animals, are included. The paper provides several results, including a characterizing of the optimal harvesting scheme, and how the harvest and stock composition are influenced by damage costs. It is also shown how the damage costs influence the economic loss of predation. The paper also demonstrates that these results may be rather sensitive to certain conditions, including the timing of the events (e.g., damage costs and predation) over the year cycle.

We develop a bioeconomic model for the management of the Barents Sea red king crab (RKC) fishery, which is a shared stock between Russia and Norway. The RKC is a well-established invasive species in the southern Barents Sea that has evolved into a very profitable fishery over the past two decades. The trade-off that resource managers face today is complicated by the many persisting ecological, biological, and economic uncertainties. We provide analytical solutions that demonstrate the existing trade-offs as well as a numerical analysis of the crab’s management, illustrating the potential for gain from cooperation associated with the unidirectional dispersal externality running from the Russian to the Norwegian zone. We first formulate the noncooperative solution and find the maximum economic yield (MEY) and maximum sustainable yield (MSY) solutions. We then analyze the cooperative solution and demonstrate numerically the effects of changing prices and dispersal intensity, together with the gains from cooperation.

Predation of wildlife and livestock by large carnivores takes place within many ecological and institutional settings. In this paper, moose predation by wolves is studied within a Norwegian institutional setting where the landowners obtain the moose harvesting value and where the wolf population is strictly controlled by the wildlife authorities. An age-structured model consisting of four categories of the moose population (calves, yearlings and adult females and males) is formulated, and both maximum yield (MY) and maximum economic yield (MEY) harvesting are studied. We find that the direct effect of higher predation pressure on an age-sex category works in the direction of higher harvesting pressure of that group. However, this direct effect is accompanied by indirect effects working through the stock abundance of all age-sex groups, and the net effect is ambiguous. In the numerical analysis, it is shown that harvest of the adult categories typically will be the optimal strategy, irrespective of the fact that calves are the main target of the wolves.

During the last few decades, the grey wolf (Canis lupus) has re-colonised Scandinavia. The current population counts some 430 individuals. With the wolf re-colonisation, several conflicts have arisen. One important conflict is due to wolf predation on moose (Alces alces). This conflict is studied under the assumption of landowner profit maximisation as well as routinised harvesting behaviour. The analysis emphasises how compensation for the predation loss affects landowner management and harvest profitability. The solutions to the landowner problems are also compared to the overall (social planner) management situation, where traffic costs due to moose–vehicle and railway collisions are included.

This paper studies the role of middlemen in open-access fisheries and how the organization of the supply chains affects resource exploitation and the level and distribution of economic rent. Imperfect competition among middlemen can help ensure that fish stocks are not depleted, which is typically the case in open-access fisheries with competitive markets. Middlemen with market power can also induce higher economic rent for the supply chain in total, but these rents mainly benefit the middlemen. The supply chains of inshore anchovy and offshore skipjack tuna fisheries in Vietnam are used as empirical examples. The analysis shows that in the anchovy supply chain, the middlemen have insignificant market power and the stock is being overexploited. In the skipjack tuna supply chain, the middlemen have oligopsony power and the stock is higher than the level that produces maximum sustainable yield.

Carnivores-livestock interactions cause human-wildlife conflicts worldwide. These interactions are present under a wide range of ecological and economic circumstances. This paper studies the relationship between predation mortality and natural mortality, when food availability affects natural mortality of the livestock. Semi-domestic Saami reindeer (Rangifer t. tarandus) herding in Norway is used as a case study. When predation affects reindeer density, food competition among reindeer changes, which changes weights and natural mortality in the reindeer population. An age-structured bio-economic model is presented, where this relationship is taken into account. While predation mortality may be additional to natural mortality in absence of food limitation, it can compensate for natural mortality in situations of food scarcity. Furthermore, due to density dependency in livestock weights, predation may increase the meat value of livestock. The paper analyzes how predation affects livestock production and economic performance under an optimized management scheme. One main result is that predation shifts the optimal harvesting composition towards calf harvesting and, therefore, the optimal stock composition among the different categories of animals. This contrasts findings in the existing bioeconomic literature. Furthermore, a changing harvesting pattern towards calf harvest is an important adjustment that highly limits the negative impact on profit of predation.

The literature on ‘fish wars', where agents engage in non-cooperative exploitation of single fish stocks or interacting fish stocks is well established, but age and stage structured models do not seem to have been handled within this literature. In this paper we study a game where two agents, or fishing fleets, compete for the same fish stock, which is divided into two harvestable age classes. The situation modelled here may be representative for many fisheries, such as the Norwegian North Atlantic cod fishery where the coastal fleet targets old mature fish while the trawler fleet targets young mature fish. We analyze the game under different assumptions about the underlying information available to each fleet and the actions of the agents. The outcomes of the games are compared to the optimal cooperative solution. The paper provides several results, which differ in many respects from what are found in biomass models. The analysis is supported by numerical examples.

We analyse the standard optimal control fishery biomass model and derive some novel results on optimal management when fish stocks are low. We show that as long as it is not optimal to let the stock become extinct and the marginal benefit of harvesting is bounded below infinity for all harvest levels, there will always be an interval with low stock sizes where it is optimal not to harvest. This result does not depend on any assumption that marginal harvesting cost per unit increases with decreasing stock size. We then prove that under weak conditions the shadow price on the fish stock always goes to infinity as the stock approaches zero. The results are generalized to a particular class of age structured models.

We analyze to what extent electricity production by non-fossil fuel replaces fossil fueled electricity production in 27 OECD-countries 1980-2014. Depending on model specification, the long run replacement coefficient is in the range of minus 0.4-1.0, which is considerably larger than found in other studies. This means that an increase in non-fossil fuel based electricity production by 10 kWh/capita replaces fossil fuel based production in the range 4-10 kWh/capita. Over all the estimated replacement is not sufficient to prevent economic growth from increasing fossil based electricity production, thus eating up environmental improvements. However, we identify two important exceptions to this. First, countries with a 'low' level of fossil based production have an Environmental Kuznets Curve (EKC) relationship when we allow for separate effects of the economic downturn after the Great Recession 2008-2009. Second, results for the EU countries indicate that the EU Emission Trading System, and possibly EU country specific policy instruments, have influenced the mix of electricity production in the intended direction.

A stage structured fishery model with three stages; recruits, immature fish and mature fish is formulated and utilized to analyse maximum sustainable yield (MSY) and optimal harvesting composition in a fishery with two heterogeneous fleets. The stage structured model developed bundles the age classes found in age structured models into stage classes based on their level of maturity, but also the pattern according to which they are harvested. Two fleets, high sea and coastal vessels, harvest respectively the immature and mature stages. The maximum sustainable yield (MSY) is studied in light of both perfect and imperfect fishing selectivity. In addition, we analyse the biomass loss of a sharing rule where the high sea trawler fleet is granted a certain share of the harvested biomass. The paper provides a theoretical extension to the literature on age structured models, and presents several new analytical results related to stage structured models which are supported by a numerical illustration inspired by the North-East Arctic cod fishery.

This paper studies the practice of semi-domestic reindeer (Rangifer t. tarandus) herding in Finnmark county in northern Norway. In this area, the Saami reindeer herders compete for space and grazing areas and keep large herds, while at the same time, the reindeer population is heavily exposed to carnivore predation by the lynx (Lynx lynx), the wolverine (Gulo gulo), and the golden eagle (Aquila chrysaetos). It is demonstrated that predation actually may improve the economic lot of livestock holders in this unmanaged local common setting. There are ecological as well as economic reasons as to why this happens. The ecological reason is that predation compensates for natural mortality; that is, increased predation reduces natural mortality, indicating that the net loss due to predation actually may be quite small. When predation reduces livestock density, the feeding conditions of the animals will improve, resulting in increased livestock weight and higher per animal slaughter value. At the same time, a smaller stock reduces the operating costs of the herders.

A generic type age‐structured fishery population model consisting of two harvestable age classes is formulated. Optimal harvest rates are determined with uniform fishing mortality and perfectly selective fishing, respectively. Selectivity allows for differentiating the fishing mortality among different age classes. Sustainable yield–biomass functions are developed, and the maximum sustainable yield (MSY) solutions are found under both exploitation schemes. The gain of perfectly selective fishing over uniform (or biomass) fishing is examined under various assumptions, and it is proved that the benefit of selective harvesting increases when the harvestable fish population becomes more heterogeneous in terms of weights, or values. In contrast to the surplus production model, or Clark model, the analysis also demonstrates that MSY with different age classes is not purely a biological concept.

During the last few decades, the number of large carnivores (wolf, bear, lynx and wolverines) has increased significantly in Scandinavia. As a result of more predation of livestock, conflicts with livestock farmers have deepened. We model this conflict using sheep farming as an example, and in instances in which farmers are given compensation for the predation loss. The compensation scheme is composed of a fixed per animal loss value (ex-post), but also a compensation just for the presence of the carnivores (ex-ante). Ex-post compensation payment is practiced in many countries where farmers are affected by killed and injured livestock, but also damages to crops. Ex-ante payment implies payment for environmental services and is also widely practiced. In the first part of the paper, the stocking decision of a group of farmers is analyzed. In a next step, the Directorate for Natural Resource Management (DNRM), managing the carnivores and compensation scheme, is introduced. The strategic interaction between the sheep farmers and DNRM is modelled as a Stackelberg game with DNRM as the leader. We find that it is not beneficial for DNRM to use ex-post, but only ex-ante compensation. The solution to the game is compared to the social planner solution, and numerical illustrations indicate that the efficiency loss of the ex-ante compensation scheme to be small.

Description of the population model with and without harvesting.

Sheep grazing is an important part of agriculture in the North Atlantic region, defined here as the Faroe Islands, Greenland, Iceland, Norway and Scotland. This process has played a key role in shaping the landscape and biodiversity of the region, sometimes with major environmental consequences, and has also been instrumental in the development of its rural economy and culture. In this review, we present results of the first interdisciplinary study taking a long-term perspective on sheep management, resource economy and the ecological impacts of sheep grazing, showing that sustainability boundaries are most likely to be exceeded in fragile environments where financial support is linked to the number of sheep produced. The sustainability of sheep grazing can be enhanced by a management regime that promotes grazing densities appropriate to the site and supported by area-based subsidy systems, thus minimizing environmental degradation, encouraging biodiversity and preserving the integrity of ecosystem processes.

A model of interaction between a renewable natural resource with capital limitations, as exemplified by the optimal investment problem of sheep farming in a Nordic context, is analysed. Both private and social optimality are considered; with the difference that a stock value related to the number of grazing animals is attached to the social management problem due to landscape preservation. The efficiency of alternative policy tools in terms of obtaining the socially optimal management scheme is discussed. The model builds on existing studies from the fisheries literature, but the important difference is that while capital is related to harvesting effort in the fisheries, capital contributes to production capacity to keep the animal stock during the winter in our farm model. The paper provides several results where both optimal steady states and the optimal approach paths are characterised analytically. The results are further supported by a numerical example.

Increased sea lice densities in the farmed salmon sector have recently led to the growing concerns in Canada, Chile and Norway as the main producer countries. The sea lice incur problems within the farmed fish industry itself as well as in wild stocks. We present a bioeconomic model for wild Atlantic salmon (Salmo solar) and explore to what extent the harvest and social benefit of wild salmon fishing in Norway are affected by sea lice-induced mortality. An age-structured population model is required to analyze the losses because the salmon post-smolts are the most vulnerable to attack by sea lice, while the harvest value is related to the three age classes of mature spawning fish. Losses are analyzed by determining the reduced harvesting value as well as the non-consumptive (conservation) value of the wild salmon stock pertinent to various sea lice-induced mortality levels. Our findings indicate that welfare and economic losses in a typical Norwegian salmon river may range from 15 to 25%. In addition, at low sea lice levels, the welfare improvement associated with selective harvest is quite modest, and is even lower when non-consumptive values are deemed important. On the other hand, when sea lice-induced mortality levels are very high, the welfare improvements of selective harvest are substantial. (C) 2015 Elsevier B.V. All rights reserved.

The paper studies the economy and ecology of sheep farming at the farm level in a Nordic context, with a crucial distinction between the outdoors grazing season and the winter indoors feeding season, and where climate conditions fix the length of the grazing season. Two different categories of animals, ewes (adult females) and lambs, and one plant species are included in our ecological model. The farmer is assumed to maximize present‐value profit where the revenue is made up income from meat and wool production. We find that livestock cycles may represent an optimal management policy. We also show that in a possible steady state with a constant number of animals and constant vegetation quantity, slaughtering either only lambs or only ewes is optimal.