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 of the life cycle of salmon, which involve 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, develop into smolts, about 12 to 15 cm, and then migrate to the open sea. The smolts then evolve into adult salmon, about 70 to 76 cm long, and stay in 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.