Salmon in the Estuary 

by Kenn Oberrecht 

In the Pacific 

Northwest, salmon are 

the most important of

all commercial and 

sport fishes, yet we 

seem to have tried our

best to place every 

conceivable obstruction 

in the path of their

survival. We've 

destroyed their habitat, 

built barriers to their

migration, polluted 

their waters, and 

overfished them. 

Oregon author Anthony 

Netboy has called 

salmon the world's

most harassed fish. 

Of the six species of Pacific salmon, five occur along the Pacific 

Northwest coast: pink, chum, sockeye, coho, and chinook. Of those, coho 

and chinook are the most plentiful in Oregon waters, but chum salmon use 

several of our coastal rivers. Sockeye seldom appear south of the 

Columbia River, and there the runs have been all but wiped out. Pink 

salmon don't spawn in Oregon but are sometimes part of the offshore 

catch. 

All Pacific salmon are anadromous, meaning that they spend most of their 

lives in the ocean but return to fresh water to spawn and die. In as much 

as estuaries are the lower reaches of coastal rivers, where salt and fresh 

water mix, all Pacific salmon use the estuaries to some extent. They must

pass through them on their way to spawning grounds. The migrating 

young, known as smolt, must also move through the estuary on their way 

to the sea. Many use the estuaries in other ways as well. 

Although some generalities apply to each species of Pacific salmon, 

certain stocks or races within a species might differ considerably in one or 

several habits. For example, we say generally that all Pacific salmon 
spawn in fresh water, but some races of chum salmon actually spawn in 

estuaries, in tidal areas near upwellings of ground water. Most other chum

salmon spawn only a short distance from the estuary, and their young 

spend about three months feeding in the tidal marshes and eelgrass beds

before migrating to the ocean. 

Sockeye fry normally migrate into freshwater lakes where they spend one 

to three years feeding before heading for the ocean. Some stocks, 

however, instead of moving into the so-called nursery lakes, head 

downstream to the brackish sloughs and backwaters of estuaries, where 

they gorge on abundant food for months prior to their seaward migration. 

Coho fry remain in their birth streams until they undergo the 

transformation that will enable them to adapt to salt water. Then as smolts

they descend to the estuary. Most linger there for a few weeks, foraging 

and growing rapidly, but some may stay for as long as a year. 

Like the coho, chinook fry remain in fresh water until they become smolt

and head for the estuary. Fall chinook might spend only a few weeks or 

months in the estuary, while spring chinook generally remain as long as 18 

months before migrating to sea. 

Pink salmon probably spend the least time in the estuary on their seaward 

migration. But they and others, studies have shown, spend at least two 

weeks feeding and growing in the rich estuarine waters. 

Perhaps one of the greatest values of the estuary to these young salmon is

the abundant food that enables them to double or even triple in size before 

migrating to sea. Size is one of the best defenses against predation. So 

estuaries are essential to the very survival of these fishes. 

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