The diagram illustrates the overall life-cycle process from spawning to maturity of a species of large fish known as the salmon.
Overall, there are three main stages for the life cycle of salmon which involves- fry, smolt, and adult salmon. Each stage takes place in a different aquatic environment, ensuring their growth and survival before they return to their birthplace to lay eggs.
In the first stage, adult salmon lay their eggs in the slow-moving upper river, where the eggs remain among the reeds and small stones for approximately 5 to 6 months. After that, fry spend approximately 4 years in the fast-flowing water of the lower river. In the second stage, the fry, which are about 3 to 8 cm long, migrate to the lower river. Then, they develop into smolt, about 12 to 15 cm. The smolt is now developed into adult salmon about 70 to 76 cm and their journey goes to the open sea, where they spend about five years. Finally, the adult salmon return to the upper river, completing the cycle by laying eggs in the same slow moving, reeds with small stones where their life began.
Each stage involves significant growth and habitat transition, which highlights the salmon’s adaptation to varied water conditions from the upper river to the lower river and open sea water throughout their life cycle.