Salmon Life Cycle

Salmon have a lifespan of three to eight years. Salmon are a kind of “super fish” that can live in both fresh water and salt water, and might travel hundreds or even thousands of miles over a lifetime! Salmon are born in fresh water and most live their adult lives in the ocean. Then they make an incredible upstream journey to spawn (lay eggs) in the same places that they were hatched. Only Kokanee salmon do not make this journey; they live their whole lives in a freshwater stream or lake.

spawn through hatch
At two to seven years old, salmon are ready to spawn. Some salmon lay eggs only once and other species spawn many times. In the fall, mature salmon change color, and return from the ocean to the spawning beds from where they were hatched. The amazing process begins with the female digging a hole in the gravel with her tail. A female salmon will lay a few thousand eggs in the hole that will be fertilized by the male fish. Eventually the new baby salmon hatch out of these eggs.

hatch through smolt/parr
Baby salmon, or alevins, first live under rocks and absorb nutrients from their attached yolk sac. Alevins continue to grow into fry. Eventually fry leave the protection of the rocks to live and grow in the current of the water. After about one year, the small fry, or smolt, follow the river to the ocean. They live at the mouth of the river where they undergo an amazing chemical change, or “smolting,” adjusting to life in salt water. As smolts continue to grow, salmon of all different species live together in schools, or groups, close to shore for safety. Finally, adult salmon go further out to sea to live their lives mostly alone.

journey home (once or repeat)
From two to six years of age, mature salmon will return to the waters where they were hatched to reproduce. To prepare for the long distance journey, salmon spend time at the mouths of the rivers where they smolted to feed and readjust to fresh water. Then salmon begin the demanding trip upstream home to spawn. Migration is extremely difficult. Salmon often have to navigate fish ladders in dams and other human created obstacles along the way. Almost all salmon will return to their birthplace once or more during a lifetime to spawn.  (image courtesy of USDA NRCS)