The most useful thing you can know about a coho isn’t what color it wants. It’s whether the fish is fresh from the salt or worn down by a week in the river, because that decides how fast you strip, how deep you fish, and whether the fly should be moving hard or barely at all. A chrome silver holding in tidewater in mid-August will chase down a fast-stripped chartreuse Clouser and try to kill it. The same fish, two weeks and twenty river miles later, may ignore that fly completely and take a small purple leech crawled past its nose. Learn to read which fish you’re standing over, and the fly selection gets much simpler.

Through most of the coho’s range the best fishing runs from mid-August into mid-September, and Alaska anchors it. Bristol Bay’s silvers show in the first week of August, and rivers like the Naknek and Nushagak are near peak by the end of the second week; the Kenai’s first run tops out over the last two weeks of August with fish in the six-to-ten-pound class, then a second, larger run of ten-to-fourteen-pounders arrives in cooler, clearer water around mid-September. Southeast Alaska fishes salt and tidewater through August and September. Farther south, the lower Columbia and coastal estuaries of Washington and Oregon peak in August and September before fish push upstream, and the Great Lakes tributaries run their landlocked silvers, averaging around five pounds, from September into mid-October once the water cools into the 60s. Wherever you fish them, the fish arrive bright and leave colored, and fly choice follows that change.