Final answer:
Most of the life of a salmon is spent in the ocean, where they grow after beginning their life in freshwater streams. They migrate between their natal streams and the ocean, returning to streams to spawn after one to four years. This cycle relies on their ability to remember their home streams using olfactory cues.
Step-by-step explanation:
The main part of a salmon's life is spent in the ocean. Salmon begin their lives in freshwater streams, where they hatch and spend the early part of their lives. They later migrate to the ocean where they grow to maturity. After spending one to four years in the ocean, they return to the very same streams they were born in to spawn. This impressive homing behavior is thought to be guided by the unique chemical signatures of their natal streams, which the salmon can detect using their keen sense of smell. Even with the presence of more predators in their home rivers over the years, salmon continue to follow their migratory patterns, aided possibly by environmental cues like the sun.
Salmon reproduction involves the female salmon laying eggs in freshwater streams, where the male fertilizes them. After a period of growth, the juvenile salmon (smolt) migrate to the ocean, where they live most of their adult lives. The migratory life of salmon is fascinating as it includes a journey from freshwater to the ocean and back, which classifies them as anadromous fish. Understanding this migration pattern is crucial for the conservation of salmon species as well as for managing fisheries that rely on salmon as a resource.