Effects of domestication on parr maturity, growth, and vulnerability to predation in Atlantic salmon

Domestication can change fitness-related traits. We investigated domestication-induced changes in fitness-related traits in Atlantic salmon (Salmo salar) under naturally enriched laboratory conditions with and without threat of predation. Selection in two strains for rapid growth for 3 and 5 generations resulted in 2 and 3 times larger sizes of under-yearling parr relative to their wild ancestor. An initially larger size and ability to outgrow prey size more rapidly resulted in lower size-selective predation mortality for domesticated individuals. Growth under threat of predation was only reduced for wild individuals, suggesting that domestication co-selects for predator-related stress resistance. Size-adjusted male parr maturation probability was 34% in the wild strain, but significantly reduced to 10% and 7% after 3 and 5 generations of domestication, respectively. Together, freshwater-stage specific survival for individuals with a domesticated background relative to individuals with ...