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Fraser River white sturgeon long-term management : objectives, strategies and uncertainties

University of British Columbia

The sharp decline of Fraser River white sturgeon (Acipenser transmontanus) in the late 1800s was the result of large catches in response to a market demand for caviar and smoked sturgeon. After a long period of indifference, the British Columbian public became concerned with the lack of white sturgeon information and probable large stock decline during the summer of 1993 with the discovery of several large white sturgeon carcasses. In September of 1994, a "catch and release" policy was implemented and met with mixed reactions. Nevertheless, uncertainties about stock reactions to harvest favoured the current cautious approach to limit retention. The objectives of this thesis are to: clarify objectives and struucture strategies for white sturgeon management; analyze uncertainty under these strategies in a stock harvest model; and discuss the role of uncertainty in management decisions and structure. It must be recognized that no perfect management solution exists. However, structuring fisheries management objectives and exploring uncertain stock reactions must be the first, crucial step to success. By simulating future events based on past stock reaction patterns, various white sturgeon harvest strategies and their ability to achieve management objectives is evaluated. This study focuses on how Fraser River white sturgeon might react under various harvest strategies designed to achieve management objectives by treating recruitment stochastically in a delay-difference model as unpredictable "states of nature." Results indicate that the probability of over harvest changes surprisingly little. This may help managers and stakeholders to assess their roles in the management process. Thus, uncertainty was quantified to show that the role of risk assessment in developing strategies to achieve long-term harvest objectives for Fraser River white sturgeon is important. While theoretical arguments are not too convincing, in practice, white sturgeon may be suitable for unusual harvest management initiatives such as individual quotas.

Thesis/Dissertation

application/pdf

2009-01-18

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http://hdl.handle.net/2429/3774

Interdisciplinary Studies

University of British Columbia

UBCV

DSpace