An Examination of Harvest Rates and Brood-Take Rates as Management Strategies to Assist Recovery of Cowichan River Chinook Salmon.

摘要

The Cowichan River fall-run Chinook salmon (Oncorhynchus tshawytscha ) population has been a serious conservation concern since 1997. I developed a stochastic life-history simulation model of both hatchery-origin and naturally-spawning Chinook in this system to evaluate management options involving specific harvest and hatchery brood-take rates. Ocean harvest was more influential than supplementation on the stock's abundance. My results suggest that this stock's recovery is unlikely to occur under current poor marine survival conditions and either the status-quo management strategy or lower harvest rates that managers are likely to find realistic. Model outputs also allowed analysis of trade-offs among management objectives involving conservation, Food, Social and Ceremonial and ocean harvests, and hatchery operations. Analyses of these performance indicators showed that under poor or intermediate marine survival conditions, the best management strategies (according to most indicators, including ocean harvest) involved the lowest ocean harvest rates examined here, i.e., 30% or 40% annually.;Keywords: Recovery planning, hatchery supplementation, fisheries simulation model, salmon management, decision analysis, conservation.