A brown trout in October is not the same animal it was in July. It has stopped eating to grow and started eating to fight: it is moving upstream, changing color, defending a patch of gravel, and hitting things out of aggression rather than hunger. Understanding that shift, and the different shift happening in the rainbows and cutthroat around it, is most of what fall trout fishing is about. This page covers the fish. Where to go is on the fall Western rivers page.
What cooling water does to a trout
Trout are most active in a band of water temperatures somewhere in the 50s Fahrenheit. Summer pushes many rivers above that band by afternoon, and the fish respond by feeding at dawn and dusk and sitting out the heat. Fall brings the water back down through the band, and for a few weeks the fish feed through the middle of the day instead of around it. As nights get cold the window narrows again toward the warmest hours, late morning to mid afternoon. A fall day is the reverse of a summer one: start late, fish through lunch, and expect little after the sun leaves the water.
Cooling water also brings the Blue-Winged Olives back, so the afternoon that looks worst, gray and drizzly, is often the best of the week. The BWO guide covers the hatch.
Brown trout before the spawn
Brown trout (Salmo trutta) and brook trout spawn in fall; rainbows and cutthroat spawn in spring. That single difference drives everything about fall fishing on a river with browns in it.
Starting in early fall the mature browns leave their summer lies and move. Fish that spent August under a logjam in a deep pool travel upstream, into tributaries or toward the gravel tailouts of the main river, looking for clean, well-oxygenated gravel of roughly pea to golf-ball size in moderate current. Males develop the hooked lower jaw, the kype, and both sexes darken and take on the butter-yellow flanks and red spots that make a fall brown look like a different species. They stop feeding selectively and become territorial. A big brown will chase a smaller trout, a sculpin, or a streamer out of its water not because it is hungry but because it is there.
The timing runs from early fall on cold, high rivers to late fall on lower ones, and it stretches over weeks on any given river. The pre-spawn period, when the fish have moved but have not yet paired up on redds, is the fishing. The spawn itself is not.
Aggression and the streamer
Streamers work in fall because they trigger a territorial strike, and that changes how you fish them. The fly should look like an intruder: a sculpin, a small trout, something with profile and movement. Sizes 2 to 6, articulated or single hook, in olive, black, yellow, or white; a Sculpzilla, a Sparkle Minnow, a Zoo Cougar, a Dungeon. Fish it on a sink tip so it gets down along the undercut banks and into the deep tailouts where staged fish hold.
Retrieve matters more than pattern. A brown defending a lie will often follow a fast strip and turn away; the same fish will crush a fly that is stripped slowly, paused, and twitched in its face. Vary it until something works. Low light and gray weather help. So does covering water: fall streamer fishing is walking and casting, not standing and drifting.
The big nymph is the other fall tool. A rubber-leg stonefly, a large Prince, or an egg pattern drifted through the same water will take staged fish that will not chase.
Respecting redds
A redd is the nest a spawning trout digs in the gravel, and a fall angler needs to be able to recognize one from the bank. Look for an oval or teardrop of gravel that is noticeably cleaner and lighter than the streambed around it, usually a foot to several feet long, in the tailout of a pool or the head of a riffle in shallow, steady current. There is often a shallow pit at the upstream end and a mound of loose gravel below it. Fish holding over it in pairs or small groups, often visible, often not spooking the way they should, are spawners.
Do not wade through redds; you crush the eggs. Do not cast to fish that are on them. A fish paired up on gravel is not feeding, and hooking it is snagging, not fishing. Walk the bank rather than the tailouts, cross on cobble at the heads of riffles rather than on fine gravel below, and if you find yourself standing in light-colored gravel in a foot of water, back out the way you came.
None of this means you cannot fish a river with spawning browns in it. It means you fish the pools, runs, and deep banks and the staged, feeding fish in them, not the shallow gravel.
The rainbows and whitefish behind the redds
Spawning browns lose eggs to the current, and rainbows, cutthroat, and mountain whitefish line up below the redds to eat them. Those fish are feeding, not spawning, and they are the ethical way to fish egg patterns in fall. A size 14 to 18 Glo Bug or bead-style egg in pale orange or peach, dead-drifted through the run below a spawning area with a small nymph behind it. Fish the deeper water downstream, not the gravel itself.
Those rainbows are also hitting streamers, because cooling water has them feeding hard ahead of winter, so a streamer day on a mixed river is not only about browns.
Reading a fall day
- Frost in the morning means the water is coldest at dawn and the fish are slow. Sleep in.
- Fish from late morning through the afternoon. The BWO window is the warmest, grayest part of that.
- Sunny, calm afternoons favor nymphs and small dries. Gray, windy ones favor streamers and Baetis.
- Check the state fish and wildlife agency for fall closures on spawning tributaries and for any seasonal gear rules. They exist on many brown-trout rivers and they change.
How to tell if you are standing on a redd
- The gravel under your boots is lighter and cleaner than the gravel around it.
- You are in a tailout or the head of a riffle, in shallow water with steady current.
- There is a shallow depression upstream of you and a loose mound downstream.
- Fish nearby are holding shallow in pairs and not spooking.
- If two or more of those are true, step out onto the bank and go around.