The diagram illustrates the life cycle of a salmon, from eggs to spawning adulthood. Overall, the salmon goes through several distinct stages, beginning in freshwater and eventually moving to the sea before returning to spawn and die.
The life cycle starts with eggs laid in freshwater. These eggs hatch after approximately three months, producing alevins — small fish that are still dependent on their yolk sac for nutrition. As they grow, they develop into fry, which are typically between five to ten weeks old and are capable of swimming.
Over the next few months, the fry mature into parr, characterized by the development of finger-like markings on their bodies. After living in freshwater for about one to three years, the parr become smolts. At this stage, they form groups and begin their migration out to sea.
In the ocean, the salmon continue to grow and develop into adults, a stage that can last from one to eight years. Finally, the mature salmon return to freshwater to spawn. After spawning, adult salmon typically die within two weeks, completing the life cycle.