The diagram illustrates the life cycle of salmon, highlighting the stages from eggs to adulthood and their adaptation to both freshwater and marine environments.
The process begins in the upper reaches of rivers, where adult salmon lay their eggs in slow-moving water, protected by reeds and small stones. The incubation period lasts approximately 5-6 months, after which the eggs hatch into fry, measuring 3-8 cm in length. These young fish migrate downstream to the lower river or estuary, where the water flow is faster. Over a period of about 4 years, the fry undergo significant growth, developing into smolt, which range in size from 12-15 cm.
The smolt then journey further downstream into the open sea, where they spend around 5 years. During this phase, they reach full maturity, growing to a length of 70-76 cm. Upon completing this stage, the adult salmon return to their birthplace in the upper river to spawn, thereby completing their life cycle.
Overall, the salmon’s life cycle consists of three distinct phases: fry, smolt, and adult salmon. The first two stages occur in freshwater, while the final stage takes place in the ocean. This ability to thrive in both freshwater and saline environments underscores the species’ remarkable adaptability.