Dynamics of Discovery and Exploitation: The Case of the Scotian Shelf Groundfish Fisheries

Abstract

The bases and shortcomings of the current models used in fisheries management are briefly examined. An alternative set of models in part based on the Volterra–Lotka equations are developed which incorporate recent advances in our understanding of the evolution of complex systems. Simulations based on a dynamic model of a Nova Scotia fishery reveal that human responses amplify rapid random fluctuations in recruitment and excite strong Volterra–Lotka type oscillations in a system that would normally repose in a stable stationary state. A dynamic, multispecies, muitifleet spatial model calibrated to the Nova Scotian groundfish fisheries is presented and used to explore the concepts of "discovery" and "exploitation." Two types of fishermen are identified, "stochasts" and "cartesians," characterized respectively as hunters, or high risk takers, and followers, or low risk takers. Significant results include the importance of calibration in providing models of relevance to the real world; the "out of phase" relationship between abundance and the ease with which fishermen locate a highly sought species and its converse; the importance of information exchange in defining the attractivity of a particular fishing zone to different fleets and the ability of the model to take into account coded information, misinformation, spying and lying; and the fact that models based on global principles, such as "optimal efficiency" or "maximum profit," are clearly of dubious relevance to the real world.