Variation in Age at First Spawning in Atlantic Salmon (Salmo salar)

Abstract

Significant differences in the proportion of mature fish in groups of Atlantic salmon (Salmo salar) of different river origins maintained under the same conditions were observed during the 1st and 2nd yr of sea rearing. Nearly all fish in sib groups originating from grilse rivers matured during the 2nd sea year, while few or no mature fish were found in the groups originating from rivers producing mainly multi-sea-winter salmon. The observations were in accordance with the life histories of the different river populations, indicating that salmon inherit rather than acquire a tendency to mature at a certain age. Key words: Atlantic salmon, maturation age, cultured salmon, river populations