Fish-Wars Revisited: A Stochastic Incomplete-Information Harvesting Game

This study employs a spatially distributed stochastic extension of the classical “fishwar” harvesting game. The model addresses the bioeconomic impact of exploiting a trans-boundary fish stock in a stochastic marine environment subject to natural fluctuations and long-term regime changes. Our goal is to study the evolution of the fishery, either with cooperative or non-cooperative harvesting, when the harvesting fleets possess only limited, possibly asymmetric, information of environmental changes. More specifically, we shall investigate how such information limitations and asymmetries will influence harvesting strategies and thus the outcome of the game. In particular we shall compare game versions that incorporate alternative information structures to determine the effect, on the evolution of the fish stock and the payoffs to the fleets, of an increase of available information (or a reduction in its degree of asymmetry). It will often be the case that, with competitive harvesting, information enrichment will be destructive both to the biological resource and to the welfare of the competing harvesters. This circumstance casts light on the design of cooperative institutional arrangements that will be stable in the presence of imperfectly predictable environmental stochasticity. As an illustration we examine, in light of the model, the history of the long-running dispute between the United States and Canada over management of their bi-national Pacific salmon fishery. The Stochastic Split Stream model, developed here, is based loosely on Canadian-U.S. harvest competition over Canada’s Fraser River sockeye salmon stock. Fraser sockeye stocks vary considerable over time both in biological productivity and in their return migration route around Vancouver Island and, thus, their accessibility to the two national fleets. In addition, the model sheds light on other aspects of the dispute. Our analysis focuses on the effects of a pronounced warming in coastal ocean conditions that began the mid-1970s and continued for two decades. This climatic regime shift contributed to dramatic increases in Alaskan salmon abundance, declining ocean survival rates for southern salmon populations and changes in the migration behavior of Fraser River sockeye that favored the Canadian fleet. These unanticipated changes destabilized cooperation under the terms of the 1985 Pacific Salmon Treaty. The positions taken by Alaska, Canada and the southern U.S. jurisdictions during the subsequent period of turmoil and renegotiation are consistent with our model results.