The diagram shows the life cycle of salmon, from the stage when eggs are laid upstream to when they develop to adult fish and return to their original spawning grounds.
Overall, this is a continuous biological cycle consisting of three main phases, beginning with salmon spawning upstream and ending when mature salmon return to the spawning grounds to continue their life cycle. In addition, salmon undergo growth in size and migration through three different habitats, including upstream, downstream, and ocean.
In the early stages, adult salmon lay their eggs among small plants and rocks in upstream areas where the water flows slowly. After about 5 to 6 months, the eggs hatch into fry, approximately 3-8 cm long. The fry then migrate downstream to area with faster currents. Here, they continue to grow and develop for about 4 years before moving on to the next stage.
After their downstream stage, salmon develop into smolt, growing to 12-15 cm in length. Next, they migrate to the open ocean, where they continue to grow for about 5 years, the longest period of their entire life cycle. In the sea, salmon grow rapidly and become adults, reaching 70-76 cm in size, significantly larger than in the two previous stages. Finally, the adult return to the upstream area of the river to spawn and lay eggs, completing their life cycle and beginning a new one.
