Influence of parental life history on maturation and smoltification in brown trout (Salmo trutta L.)

The developmental pathways of the offspring of three groups of trout, Salmo trutta L., with known life histories were compared: one group from a freshwater resident population and two groups from an anadromous population (fish that have smoltified and fish that have not). The fish were hybridized within a group, and 27 families were obtained and reared mixed in two tanks. Tracking fish specimens was possible thanks to individual passive integrated transponder (PIT) tagging. All families followed different life pathways. Faster growth favored early smoltification and maturation at the age of 1+ in males that had not smoltified. In addition, both processes were clearly also influenced by inherited factors. Fish of freshwater resident origin smoltified more infrequently, and males matured earlier than did fish from the migratory population. The offspring of parents from the migratory population, which did smoltify during their individual histories, smoltified early (in the second year) more often than offspring of non-smoltified members of the population.