UBC Theses and Dissertations

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UBC Theses and Dissertations

Transboundary management of a fish stock under climate variability : the case of Pacific sardine in the California current ecosystem Ishimura, Gakushi


The time variant/asymmetric distribution of a fish stock caused by ocean climate variability is one of the challenges that must be overcome to establish cooperative management of a transboundary fish stock. Pacific sardine (Sardinops sagax) exhibits extreme decadal variability in its abundance and geographic distribution that corresponds to water temperature regime shifts within the California Current Ecosystem. It is a transboundary fish stock and targeted by Mexican, American and Canadian fisheries, and the three countries do not currently have a cooperative management arrangement. This thesis explores the economic and conservation consequences of non-cooperative management, and the potential benefits of full/partial cooperative management of Pacific sardine, and studies the stability of cooperative management under ocean climate variability. The core of the thesis is presented in Chapters 2-4, with an introduction given in Chapter 1 and a conclusion in Chapter 5. Appendix A and B provide background information on Pacific sardine and the Pacific sardine fishery, respectively. Chapter 2 develops a three-agent bioeconomic framework to investigate the impact of ocean climate variability on stock abundance and geographic distribution. A game theoretic analysis was conducted to evaluate the conservation and economic benefits of various management strategies. The results show that under a regime of ocean climate variability, a country having a dominate share of the resource within its waters cannot achieve effective unilateral conservation for optimal economic benefits due to the actions of free-riders. Chapter 3 conducts simulations to evaluate the stability of full and partial cooperative management of Pacific sardine under various climate variability scenarios. The results show that in all scenarios, ocean climate variability is an obstacle to the formation of stable, fully-cooperative management of Pacific sardine fisheries as operated by the three countries. Chapter 4 estimates the cost of delaying cooperative management of this fishery, and how costs are incurred due to such delays. The results suggest that the cost of delaying cooperative management is significant for a country having a dominant share, while countries that have minor shares gain economic benefits from delaying cooperative management.

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