The diagram illustrates the stages in the life of the salmon, from birth to maturity.
It is clear that there are six* main stages as the salmon develops from egg to mature adult. We can also see that salmon spend time in three distinct locations during the cycle, moving from river to estuary to ocean and then back upstream.
Salmon begin their lives in rivers where the adult fish lay and incubate their eggs. After emerging from eggs, the young salmon spend the next stage of their lives being reared in freshwater areas. Then, at some point in their development, the fish swim downstream to river estuaries where rearing continues.
Following the estuary rearing period, the maturing salmon migrate to the ocean, where they eventually become fully grown adults. Finally, the adult fish travel back upstream to spawning areas of rivers; here they reproduce and lay their eggs, and the life cycle begins anew.