The diagram illustrates the life cycle of salmon, a species of large fish, showing the different stages of its growth and the locations where each stage occurs. Overall, the process consists of three main stages, starting with the eggs in the upper river and ending with the adult salmon in the open sea.
Initially, salmon eggs are laid among reeds and small stones in the upper river, where the water flows slowly. This stage lasts approximately 5 to 6 months. Once hatched, the young salmon, known as fry, measure between 3 and 8cm in length. The fry then moves to the lower river, where the water flows faster, and they remain there for around 4 years as they continue to grow. During this time, they develop into smolt, which are larger, measuring about 12 to 15cm.
After spending several years in the river, the smolt migrate to the open sea, where they mature into adult salmon. At this stage, they grow significantly, reaching a length of 70 to 76cm. The adult salmon stay in the sea for about 5 years before returning to the upper river to lay eggs and begin the cycle again.