The diagram illustrates the life cycle of a salmon.
Overall, the salmon goes through several stages, beginning in fresh water, moving to the sea, and finally returning to fresh water to reproduce.
The life cycle starts when eggs are laid in fresh water. After around three months, the eggs hatch and alevins appear. At this stage, alevins are not able to feed themselves and depend on nutrients from their yolk sacs. After several weeks, they develop further and begin to swim. At this point, they are known as fry.
After a few months, fry grow and become parr, which are identified by dark marks on their bodies. The next stage is called smolt, which lasts from one to three years. During this time, salmon form groups and migrate from rivers to the sea.
Salmon then live in the ocean for between one and eight years. When they become fully mature, they return to fresh water to spawn. After spawning, adult salmon survive for only a short period, usually around two weeks.