Salmon Life Cycle

The Journey Begins: Eggs in Gravel

A salmon's life starts in the cold, clean gravel of a stream. Female salmon dig nests called redds in the streambed using their tails. They lay thousands of tiny orange eggs, which the male fertilizes. The parents then cover the eggs with gravel to protect them from predators and strong currents.

Alevin: Living Off the Yolk Sac

After 6-20 weeks (depending on water temperature), the eggs hatch into alevin — tiny fish with a large yolk sac attached to their belly. The alevin stay hidden in the gravel, living off the nutrients in their yolk sac. They don't need to find food yet; everything they need is attached to them!

Fry: First Swim

Once the yolk sac is absorbed, the young salmon emerge from the gravel as fry. Now they must find their own food — mostly tiny insects and plankton. This is a dangerous time: predators like birds, larger fish, and even other salmon are hunting for an easy meal.

Fry need cold, clean water with plenty of places to hide (like overhanging plants, logs, and rocks). This is why protecting riparian habitat — the vegetation along streams — is so important for salmon.

Parr and Smolt: Preparing for the Ocean

As fry grow, they develop dark vertical bars on their sides and are called parr. These camouflage markings help them blend into the stream bottom. Parr spend anywhere from a few months to over a year in freshwater, depending on the species.

When it's time to migrate to the ocean, amazing changes happen. The parr transform into smolt — their bodies become silvery, their scales toughen, and their internal chemistry changes to prepare for saltwater. This process is called smoltification.

Ocean Years: Growing Strong

Smolt swim downstream to estuaries (where rivers meet the ocean) and then out to sea. In the vast Pacific Ocean, salmon spend 1-5 years feeding and growing. They eat krill, small fish, and squid, traveling thousands of miles.

Ocean conditions are critical. Warm water years, changes in food availability, and predators all affect how many salmon survive to return home.

The Journey Home: Spawning Run

When adult salmon are ready to spawn, they navigate back to the exact stream where they were born — sometimes traveling hundreds of miles upstream! Scientists believe salmon use a combination of the sun, Earth's magnetic field, and their sense of smell to find their way home.

The journey upstream is exhausting. Salmon stop eating once they enter freshwater and live off stored body fat. They swim against strong currents, leap over waterfalls, and navigate around obstacles (or get blocked by dams and culverts that humans have built).

Spawning and the End of Life

When salmon reach their home stream, they spawn — laying and fertilizing eggs just as their parents did. Most Pacific salmon (including all five species in Puget Sound) die shortly after spawning. Their bodies become food for other animals and fertilizer for the stream and forest.