In late autumn, the female salmon buries fertilized eggs in stream bottom gravel nests called redds. The eggs hatch into alevin or sac fry in late spring, and the yolk sac is gradually absorbed.
Three to six weeks after hatching, alevins emerge from the gravel to seek food and are called fry.
Fry quickly develop into parr with camouflaging vertical stripes. The parr are two inches long. They feed and grow for one to three years in their native stream before becoming smolts.
Smolts are silver colored and approximately 6 inches long. In the spring, smolt body chemistry changes; they now weigh about 2 ounces and are ready to enter salt water. They migrate to the ocean where they will develop in about two to three years into mature salmon weighing about 8 to 15 pounds.
After two to three years at sea, adult salmon weighing 8 to 15 pounds return to their native stream to repeat the spawning cycle.
Spawned-out salmon, called kelts or black salmon, return to the ocean or overwinter in the river.