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The diagram illustrates the different stages of development of a salmon.

Overall, salmon migrates to three environments in the life cycle: river, estuary and ocean. It only spawns in the river and becomes mature in the ocean.

In detail, in the first stage, a salmon lays a large number of eggs in the river. Then, these eggs are incubated at the appropriate temperature of the river for a few weeks. Next, young tiny fishes hatch out of these eggs to water outside. After that, they are reared in the freshwater before moving into an estuary, where the freshwater and seawater meet. During the estuary rearing period, salmon become larger in size due to the rich-nutrient foods this water contains. From the estuary, they move into the ocean and migrate to rearing areas. Here, they grow and mature day by day. After being adult salmon, they come back to the river to spawn, begining a new cycle.