Science Branch, Stock Assessment Division Pacific Biological Station (original) (raw)

At the eleventh annual meeting of the North Pacific Anadromous Fish Commission in 2003, the Working Group on Stock Assessment discussed the possibility of assembling data other than catch to assess the status of salmon. In this report we apply a consistent analytical approach to several data types frequently used to index Pacific salmon in Canada. We compare results using different data types by examining the influence of three recent regime shifts. Conclusions from our evaluation of effects from the 1977 and 1989 regime shifts depended on which of three salmon abundance indices (catch, escapement, and total returns) and two survival indices (marine survival and recruits per spawner) were used. For instance, abundance shifts did not necessarily correspond with changes in survival, and regional variations existed, at least for coho. Results from our analysis confirm that different interpretations of salmon "status" may result, depending on which index is used.