Wild Salmon Life Cycle
Arriving at her home stream, a female
builds a nest, or redd, in ne, clean gravel.
As a female deposits her thousands of eggs, a male releases milt, fertilizing
them. Both male and female salmon die soon after spawning, except steelhead
and cutthroat, which may survive another year or more to spawn again.
Tiny yolk-sac fry, or alevins, hatch after 2
to 8 months. They stay in the gravel for
another 1 to 3 months until the food from
the yolk sac is used up. They need cold,
pure water to breathe and wash away
their wastes.
The fry emerge from the gravel and begin to feed
on their own. Many are lost to predators,
competition, or failure to adapt to stream
conditions. Some types of salmon begin their
migration downstream soon after emergence,
while others stay in freshwater for a year or more.
During migration the fry are vulnerable to predators,
such as birds or northern pikeminnow, walleye, and bass,
which thrive in the reservoirs. Seven to 15 percent die
passing each dam.
By the time they reach the estuary, the fry have
become smolts, and their bodies are adapting to
saltwater. Here they linger to feed and grow before
entering the ocean. Predators, unfavorable conditions,
and failure to adapt will deplete their numbers further.
After 1 to 7 years in the ocean, the adult salmon that
have survived countless hazards from predators, ocean
conditions, and commercial harvest return to the
Columbia River and head for their home streams.