Salmon and Steelhead

In recent decades, dwindling Pacific salmon and steelhead stocks have prompted restrictions on commercial and recreational fishing in order to restore threatened and endangered species throughout the Northwest. Runs are highly variable from year to year; for more information about fish populations and fishing restrictions, see the Oregon Department of Fish and Wildlife’s website, www.dfw.state.or.us [1].

The salmon’s life cycle begins and ends in a freshwater stream. After an upriver journey from the sea of sometimes hundreds of miles, the spawning female deposits 3,000–7,000 eggs in hollows (called redds) she has scooped out of the coarse sand or gravel, where the male fertilizes them. These adult salmon die soon after mating, and their bodies then deteriorate to become part of the food chain for young fish.

Within 3–4 months, the eggs hatch into alevin, tiny immature fish with their yolk sac still attached. As the alevin exhaust the nutrients in the sac, they enter the fry stage, and begin to resemble very small salmon. The length they remain as fry differs among various species. Chinook fry, for example, immediately start heading for saltwater, whereas coho or silver salmon will remain in their home stream for 1–3 years before moving downstream.

The salmon are in the smolt stage when they start to enter saltwater. The 5–7-inch smolts will spend some time in the estuary area of the river or stream while they feed and adjust to the saltwater.

When it finally enters the ocean, the salmon is considered an adult. Each species varies in the number of years it remains away from its natal stream, foraging sometimes thousands of miles throughout the Pacific. Chinook can spend as many as seven years away from its nesting (and ultimately its resting) place; most other species remain in the salt for 2–4 years. Spring and fall mark the main upstream runs of the Pacific salmon. It is suspected that young salmon imprint the odor of their birth stream, enabling them to find their way home years later.

The salmon’s traditional predators such as the sea lion, northern pikeminnow, harbor seal, black bear, Caspian tern, and herring gull pale in comparison to the threats posed by modern civilization. Everything from pesticides to sewage to nuclear waste has polluted Oregon waters, and until mitigation efforts were enacted, dams and hydroelectric turbines threatened to block Oregon’s all-important Columbia River spawning route.