Harvesting and conserving a species when numbers are low: population viability and gambler's ruin in bioeconomic models

In bioeconomic models of renewable resources, population viability is eithe r ignored entirely or the minimum viable population (MVP) is considered a c risp threshold below which a species is driven to extinction. Neither is co nsistent with ecological science. The purpose in this paper is, firstly, to enhance ecological realism in economic models by incorporating insights re garding population viability from conservation biology. We consider the eff ects of chance on optimal management and briefly discuss key results regard ing population viability as derived by biologists. Second, as a means to 'b alance interests and morality', we suggest a fuzzy compromise between the e conomist's and the biologist's preferred stock sizes. (C) 2001 Elsevier Sci ence B.V, All rights reserved.