The provided diagram illustrates the various stages in the life cycle of a salmon, beginning from the egg stage in fresh water and concluding with the spawning adult. Overall, the process is cyclical and spans several years, requiring the fish to transition between fresh water environments and the sea to complete its development.
The cycle commences with eggs laid in fresh water, which hatch after approximately three months. The resulting alevin feed on their yolk sacs for several weeks before maturing into fry, which are five to ten weeks old and capable of swimming. Subsequently, the fish develop into parr, characterised by 'finger' markings, and eventually reach the smolt stage at one to three years of age, at which point they group together and migrate to the sea.
Once in the ocean, the salmon spend between one and eight years maturing into adults. The final phase involves the adult salmon returning to fresh water to spawn. This spawning adult stage is relatively short, as the fish die within two weeks of reproduction, thereby completing the life cycle and allowing the process to begin anew with the next generation of eggs.