UBC Theses and Dissertations
Analysis of stock-recruitment dynamics of British Columbia salmon Wong, Fred Yuen Churk
An overview of stock-recruitment dynamics for major B.C. salmon (Oncorhynchus spp.) stocks is presented. Stock-recruitment patterns range from linear relationships to "Ricker" type relationships to no relationship at all. However, stocks for which there are accurate escapement estimates generally show patterns expected from stock-recruitment theory. It is concluded that errors in stock definition, mixed catch allocation, and spawning counts bias optimum escapement estimates downward so that poorly monitored stocks may become severely overexploited without being noticed. Because of poor escapement counts and/or difficulties in separating mixed catches, optimum escapements for many B.C. salmon stocks, which account for about half of the total B.C. production, cannot be estimated. Most stocks for which optimum escapement can be estimated are now being severely depleted. Restoration of these stocks by increasing escapement to optimum levels would increase the total catch by at least 40% of the current yield. Further, experimental management by increasing escapement appears to be the best policy for most of the other stocks.