Effects of commercial fishing on adult Atlantic salmon (Salmo salar) in a Quebec river

Abstract

Despite an absence of freshwater exploitation, the adult salmon run in the Matamek River, Quebec, declined during 1975-1980 to <23% of the level thought to occur there prior to 1967. Returns in 1979 and 1980 of adults tagged as smolts were 1.0% and 0.9%, respectively. Numbers of emigrating smolts and their corresponding adult returns are not significantly correlated, although we observed a trend towards more salmon (2 sea year fish) returning with larger numbers of migrating smolts. Since 1967 there is noted a decrease in the age at which returning adults smolted and females appear to now constitute a larger percentage of returning grilse and salmon. These, and other changes in life history characteristics, appear to be caused solely by commercial exploitation.