The provided diagram illustrates the life cycle of a sea creature called a salmon, highlighting the different stages of its development and the environments it inhabits.
Overall, it is crystal clear that the salmon undergoes three distinct growth stages – fry, smolt, and adult – while migrating between freshwater and marine habitats. The entire life cycle lasts around 10 years, with the longest periods spent in the lower river and the open sea.
Focusing on the initial stage, adult salmon return to the upper river, where the water is slow-moving, to lay eggs among reeds and small stones. After approximately 5-6 months, the eggs hatch into fry measuring 3-8 cm. These young fish then move downstream to the lower river, which is fast-flowing. They remain there for about four years, during which they grow and develop into smolt, reaching a length of 12-15 cm.
In the final stage, smolts migrate to the open sea, where they spend roughly five years. During this period, they mature into adult salmon, growing significantly larger to 70-76 cm. Once fully developed, the adult fish swim back upstream to the upper river to reproduce, thereby completing the cycle.