The alevin carries a yolk sac which will provide food for two to three months. Once the nutrients in the sac are absorbed, the free-swimming fry must move up into the water and face a dangerous world. The fry may live in fresh water for a year or more, or may go downstream to the sea at once - it varies by species. Fry ready to enter salt water are called smolts. Whenever they do migrate, they face predators, swift currents, waterfalls, pollution and competition for food.
Young salmonids stay close to the coastline when they first reach the sea.
After their first winter, they move out into the open ocean, and, depending on the species, spend from one to four years eating and growing in the north Pacific Ocean. Then they return to their home streams, spawn and die. From each thousand eggs that were laid, only a few adult salmon survive to perpetuate their species. Hatcheries, like Robertson Creek, greatly increase the number of survivors by protecting the eggs and fry through the critical early development of their life.