Gardner Brown

Heterogeneous Preferences Regarding Global Climate Change

We examine the structure of preferences for mitigating impacts of global climate change that will not occur during the lifetimes of most who are alive today. Because no market data exist for such distant markets, a statedpreference approach is used. The analysis is based on the random-parameters logit model, and the results indicate substantial heterogeneity in respondent preferences, that mean willingness to pay is a significant and increasing function of the scope of the impact, and, provocatively, that respondents have the same preferences over the two very different time horizons that we consider.

Harvest policies and nonmarket valuation in a predator — prey system

Abstract Although prey may not have commercial value, their economic value can be ascertained in a predator-prey model if the predator has a harvest value. The economic optimal (recovery) path of the predator and prey are carefully described when growth is quadratic in the predator (prey) and linear in prey (predator). Parameter values, in part, resembling Pacific halibut are used to provide numerical illustrations.

A metapopulation model with private property and a common pool

Abstract A metapopulation illustrated by barnacles has a spatial distribution and a two-stage life cycle in the model developed here. Space limits expansion. Introducing a profitable harvest activity of adults leads to harvest at only one site, a solution driven by biological increasing returns. The model is of interdisciplinary interest because the natural resource has common property characteristics in its larval stage, but a private property character in its adult stage. The model permits economic valuation of lost habitat.

Implications of Alternative Measures of Natural Resource Scarcity

We argue that the most commonly used measures of natural resource scarcity are deficient. The discussion begins with some general comments on natural resource scarcity, then turns to a description and evaluation of each of the major scarcity indices: unit cost, product output prices, and rental rates. Rental rates or a useful proxy, marginal discovery costs, are preferred over the rival measures. But there are important instances where good scarcity indicators may be entirely absent.

Optimal recovery paths for perturbations of trophic level bioeconomic systems

Abstract This paper examines optimal recovery paths following perturbations (e.g., El Nino) in a coupled ecosystem. A simple 2-trophic level model is developed in which the harvested species also feeds upon a prey species. As might be expected, it is optimal to refrain from harvesting when both species are severely impacted by the perturbation. Perhaps surprising, however, is the result that it may sometimes be optimal to reduce the harvested species even more following some perturbations. Generally speaking, the less impacted are primary (harvested) species relative to secondary species, the more likely it will be that a pre-recovery harvesting phase is necessary.

Resistance economics: social cost and the evolution of antibiotic resistance

Daily and Ehrlich have described the current state of our epidemiological environment in chilling detail. While their point is that human beings interact and affect the epidemiological environment in a variety of ways, the development of antibiotic resistance in bacteria strikes us as one aspect that we can begin to analyse immediately. The evolution of resistance to antibiotics is a function of their use by humans. The more we use, the more selective pressure is placed upon bacteria to develop resistance. This is further complicated by how they are used. Both the duration and the amounts used affect the change in the level of resistance. Finally, the primary feature driving the concern over the use of these drugs is that the evolution of resistance makes these ‘miracle’ drugs exhaustible. We can try to develop new and better antibiotics, but it is uncertain how successful we will be and how expensive they will be if we are successful.

A Predator-Prey Model with an Application to Lake Victoria Fisheries

Greater complexity in renewable resource models is achieved by acknowledging that species interact through a predator-prey relationship in which both species are harvested. The price of greater complexity is that traditional concepts, such as maximum sustained yield (MSY), have to be revised dramatically. Moreover, having chosen greater complexity, fishery biologists and other researchers must choose an explicit value for each fish, a rate of exchange of one species for every other species. Policy makers and social scientists in Tanzania, Kenya, and Uganda with a keen interest in Lake Victoria fisheries regard the resource as a tool for furthering socioeconomic goals, such as foreign exchange earnings, employment for women, and nutrition. Comparative analysis allows policy makers to understand the consequences of choosing these goals in addition to economically efficient resource use. Foreign exchange earnings, employment for women, and healthy people are other goals promulgated by Tanzania, Kenya, and Uganda in the management of Lake Victoria Fisheries. The conflicts among social goals are evident in the bioeconomic predator-prey model: a goal favoring a particular species reduces the sustainable harvest of another species. Data from Kenya are used to estimate the population dynamics equations.

When a High Discount Rate Encourages Biodiversity

Include land in a neoclassical growth model and introduce a standard biogeographic relation between species recliners (biodiversity) and land. Assume that species provide utility. The optimal constant amount of land preserved for species is obtained from steady-state conditions. Contrary to conventional wisdom, a high discount rate preserves more land when the elasticity of substitution between goods and species exceeds unity or when this elasticity is less than unity and technology is such that the output effect of a change in the interest rate exceeds the substitution effect. Copyright 1999 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.

Different property rights regimes in the Lake Victoria multiple species fishery

Greater ecosystem complexity is recognized by studying a two species predator–prey model under two property rights regimes: free entry and a system such as individual quotas which execute an economically optimal solution. A bottom-up management experiment is discussed in the context of Lake Victoria fisheries.

Preserving endangered species and other biological resources

Abstract The expected future value of endangered species and other biological resources is extremely uncertain inasmuch as it depends on the future discovery of knowledge as well as future tastes. The economics discipline has no special advantage in this unenviable set of circumstances. Nevertheless, this paper sets forth a few simple economic principles which are essential for saving substantial biological resources.