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Evaluating the impacts of current and alternative harvest strategies on salmon populations and fishing fleets using the Skeena River as a case study

University of British Columbia

Salmon fishery management is complicated, and involves a balancing act between the divergent objectives of stakeholders, requiring decisions with uncertain information while pressured by time constraints. Unfortunately, the trade-offs between objectives are not always quantitatively evaluated, which means conflicts arising when conservation or harvest objectives are not met cannot be quantitatively balanced. This thesis addresses several major challenges faced by salmon fisheries managers, including: balancing catch and escapement of multiple stocks in mixed stock fisheries; estimating run timing; and modeling in-season management processes. Five new models were developed to explore these challenges, using the five species of Pacific salmon and steelhead returning to the Skeena River, as well as their fisheries and management system, as a case study. First, a new harvest control rule (HCR) was developed using dynamic programming. Second, an improved run reconstruction method was developed to estimate run timing and catchability in the fisheries of the Skeena River. Third, a new application of linear programming was used to optimize harvest within the fishing season, and as a fisheries planning model. Fourth, a Bayesian state-space model was developed to produce an improved in-season run size estimation model. Finally, these models and outputs were combined into a closed loop simulation to test the outcomes of different HCRs. The results and models developed in this thesis allow managers to evaluate the likely outcomes of different HCRs, improving their ability to make quantitative trade-offs between different objectives. The tools developed in this thesis can be directly applied to the Skeena River management system, either piecemeal to improve particular elements of the system or integrated into the existing management process to provide the basis of a management strategy evaluation. More importantly, the tools and lessons learned can be generalized and applied to other salmon and non-salmon fisheries.

Text

2018-11-05

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/67750

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/