By the time salmon reach twelve to fifteen centimetres, they are termed ?smolt?, and at this time they migrate further downriver into the open sea. After five years at sea the salmon will have grown to adult size, which is between seventy and seventy-six centimetres. They then begin swimming back to their birthplace, where they will lay their eggs, and the cycle starts anew.
In summary, the salmon passes through three distinct physical stages as it grows to maturity. Each of these stages takes place in a very different aquatic location. It is noteworthy that the first two stages of this fish?s life occur in a freshwater environment, while the third stage is lived in saltwater.