Ken Schultz's Field Guide to Saltwater Fish - Macaw Pets store

Salmon, Coho (continued)
not return to spawn until age 3. All coho salmon, whether
male or female, spend their first year in the stream or river
in which they hatch.
The timing of runs into tributaries varies as well. Coho
salmon in Alaska, for example, enter spawning streams from
July through November, usually during periods of high
runoff. In California, the runs occur from September
through March, and the bulk of spawning occurs from
November through January. Run timing has evolved to
reflect the requirements of specific stocks. In some streams
with barrier falls, adults arrive in July when the water is low
and the falls are passable. In large rivers, adults must arrive
early, as they need several weeks or months to reach headwater
spawning grounds. Run timing is also regulated by
the water temperature at spawning grounds: Where temperatures
are low and eggs develop slowly, spawners have
evolved early run timing to compensate; conversely, where
temperatures are warm, adults are late spawners.
Little is known of the ocean migrations of coho salmon.
Evidently, there are more coho salmon in the eastern Pacific
and along the coast of North America than in the western
Pacific. High-seas tagging shows that maturing southeast
Alaska coho move northward throughout the spring and
appear to concentrate in the central Gulf of Alaska in June.
They later disperse toward shore and migrate along the
shoreline until they reach their stream of origin. Although
most coho do not seem to migrate extensively, tagged individuals
have been recovered up to 1,200 miles from the
tagging site.
Food and feeding habits. In the ocean, coho salmon
grow rapidly, feeding on a variety of organisms, including
herring, pilchards, sand lance, squid, and crustaceans. Like
all Pacific salmon, the coho does not feed once it enters
freshwater on its spawning run.
Salmon, Coho 169