Uncertainty, resource exploitation, and conservation: lessons from history.

The r e are currently many plans for sustainable use or sustainable development that are founded upon scienti f ic information and consensus. Such ideas ref lect ignorance of the history of resource exploitation and misunderstanding of the possibility of achieving sc ient i f ic consensus concerning resources and the environment. Although there is considerable variation in detail, there i s remarkable consis tency in the his tory of resource explo i ta t ion : resources are inevitably overexploi ted, of ten to the point of collapse or extinction. We suggest that such consistency is due to the following common features: (i) Wealth or the prospect of wealth generates poli t ical and social power that is used to promote unlimited exploi ta t ion of resources . ( i i ) Sc ient i f i c understanding and consensus is hampered by the lack of controls and repl icates , so that each new problem involves learning about a new system. (iii) The complexity of the underlying biological and physical systems precludes a reductionist approach to management . Optimum levels of exploi tat ion must be determined by tr ia l and error . ( iv) Large levels of natural var iabi l i ty mask the effects of overexploitation. Initial overexploitation is not detectable until it is severe and of ten i rrevers ible . In such c ircumstances , assigning causes to past events is problematical, future events cannot be predicted, and even wellmeaning attempts to exploit responsibly may lead to disastrous consequences. Legislation concerning the environment often requires environmental or economic impact assessment before action is taken, Such impact assessment is supposed to be based upon sc ient i f ic consensus. For the reasons given above, such consensus is seldom achieved, even after collapse of the resource . For some years the concept of maximum sustained yield (MSY) guided efforts at fisheries management. There is now widespread agreement that this concept was unfortunate. Larkin (1) concluded that fisheries sc ient is ts have been unable to control the technique, dis t r ibut ion , a n d