The diagram illustrates how a salmon grows during its lifespan.
Overall, the life cycle of salmon lasts nearly ten years. It is also noticeable that there are three main stages from eggs to mature adult salmon happening in three different environments.
The life cycle of salmon begins in an upper river, where has slow-moving water. Salmon eggs are located under the reeds and near small stones. Between 5 to 6 months, salmon eggs hatch and become “fry” that are very small, and the fry length is 3 to 8 cm. After that, they move to a lower river with fast-flowing water and survive there. After 4 years living in this place, they grow and become “smolt”, the size of them increasing from 8 to 15 cm.
During the third stage of the life cycle, the smolt moves to the open sea to live. In the open sea, they live for nearly five years and undergo the biggest change in their lives. They become adult salmon, and their size grows from 15 to 75cm. In this final stage, adult salmon return to the old place where they were born by the mother salmon, and they lay new salmon eggs. Then, a new cycle of salmon begins.