Emergence of efficient extraction in social-ecological models for fisheries
With a majority of the world’s fisheries either exhausted or diminished due to overfishing, the problem of designing mechanisms for managing common-pool resources has gained important practical relevance. While the ecological theory for harvesting renewable resources demonstrates the existence of a socially optimal level of resource extraction, individual fishers have an incentive to extract at a faster rate in order to sell more fish. This is an example of the ‘tragedy of the commons,’ through which a group of rationally acting individuals overexploit a resource and consequently are worse off than a group that extracts at the socially optimal level. One way to resolve this social dilemma is the establishment of a social norm by which extractors punish those who overexploit. Recent work has shown that such a social norm makes socially optimal extraction an evolutionarily stable strategy, meaning that an established group of socially optimal extractors cannot be invaded by overexploiters. However, a relevant question to ask is whether socially optimal extraction can emerge in a group that starts out with different extraction levels. To explore this question, we will consider a general framework for describing the distribution of extraction levels in a group of fishers and investigate how they adjust their extraction levels in response to the competing incentives of catching fish and avoiding punishment for overfishing. We will employ a range of analytical approaches, including adaptive dynamics, mean-field games, and landscape gradient dynamics, to examine whether groups of fishers can achieve socially optimal resource extraction in the long-run.