Where to Find Big Bull Trout in the West

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Bull trout are not like other trout. First, they are not trout at all—they are chars. Second, unlike rainbows and brown trout, bull trout outside of Alaska and Canada have been declining in number and range for decades. To spawn successfully, they require extremely cold, pure river water, typically in the upper reaches of freestone watersheds.

There are few rivers left in the lower 48 states where it is legal to fish for them at all. The vast majority of these places are in Idaho’s Snake River tributaries, with a couple of rivers on the Oregon side of the Snake where (for now) targeting bull trout on a strict catch-and-release basis is still allowed.

For anglers, bull trout being a char is not just some fun fact about nature. It is a critical factor in determining where you will find and catch them in the summer months. The native rainbow and cutthroat spawn in the late winter and spring, but bull trout spawn in the fall. In an adaptation that must have been perfect during the ice age, they don’t even begin spawning until they find stream water that is colder than 50 degrees. That happens in the headwaters of rivers in the fall.

Bull Trout Feeding

But these headwaters don’t have enough food to grow trophy bull trout. When bull trout reach 12 to 14 inches in length, the energy input they get from feeding on insects is no longer enough to allow them to grow fast. To get bigger, they need to start eating forage fish, and the headwaters of most freestone streams don’t have enough of a forage fish base for that to happen.

This leads to a fundamentally important aspect of bull trout populations—and how to find and catch the trophies. Basically, the bull trout population divides itself in two parts. Relatively small fish simply live their whole lives as residents in smaller, cold rivers. They may not achieve sizes of over 16 inches even if they live a long time, but they can successfully spawn well before that size. But another group of bull trout will migrate downstream to bigger, more fertile water, where they feed for much of the year before migrating back into tributary streams in the summer and fall to spawn.

In Idaho, for example, these migrations occur as bull trout use the main stem of the Snake River and the lower sections of its biggest tributaries as their feeding zone, and then migrate back upstream into tributaries in the summer and fall to spawn. The same pattern occurs in bull trout populations that use Lake Pend Oreille as the main source of food (the state record catch-and-release bull trout, a 30-inch fish, came from the Kootenai River in Bonner’s Ferry near Lake Pend Oreille). Essentially, trophy bull trout use large, fertile water bodies like the Snake River in much the same way that steelhead use the ocean: they feed and get big there, then they swim up smaller rivers to spawn. Bull trout can do this every year for more than a decade, as they are long-lived fish.

Where to Find Big Bull Trout

Following this pattern of feeding in big water and migrating to spawning grounds in the summer, bull trout will move miles upstream in Snake River tributaries by late July. Note that not all of these big fish are moving from the Snake River itself. Some tributaries, like the Clearwater and Salmon, are large enough in their lower reaches to provide the food migratory bull trout need.

The bull trout movement is often in tandem with some salmon and steelhead runs. Bull trout are voracious feeders of small fish and, at times, salmon eggs. But for the most part, by the end of summer bull trout high in tributaries are resting and waiting in big holes, where they don’t need to spend much energy to hold position, and where the water is coolest.

Their migration presents anglers with the chance to catch trout that are two feet long on flies in small mountain streams in the summer, which is every bit as much fun as it sounds. But the same long migration that gives you that chance can also make bull trout frustrating to find. It sounds like knowing that migrating big bull trout are somewhere in the Clearwater River drainage in August would put you well on the way to easily catching trophy fish.

That is, until you realize that the Clearwater is nearly 50 miles long. And that many of the migrating bull trout may be in the tributaries of the river, rather than the main stem and the Clearwater watershed is 9,400 square miles. And that bull trout, in my experience, tend to prefer to spawn in sections of rivers that are miles away from roads. And that the habit of trophy fish to clump up together in certain holes means that there are long sections of any river where you are not likely to find any big fish. And that the exact timing of their migration can vary not only from drainage to drainage, but also from year to year in the same drainage, so even if you track them down in on place one year, they may not be in that part of the river at the same time the next year.

The truth about DIY trophy bull trout fishing is that it takes a significant level of “trout bum” dedication and physical effort, spread out over time, to be successful.

You can do yourself a favor by focusing your efforts. Step one is to target a promising tributary in a drainage known to have migratory bull trout—one you can commit to getting to and learning. (Migratory populations have been documented in pretty much all these drainages, including rivers in the Salmon, Clearwater and Pend Oreille drainages).

Step two is to get a good map, showing details of road access to trailheads, hiking trails and, critically, topo lines. Keep in mind as you look at the maps that bull trout like to take up holding positions near excellent spawning habitat. Spawning habitat means a stretch of riverbed with pea-sized to half-dollar sized gravel that will not go dry at low water in October. Bull trout will not spawn in silt or on bedrock streambeds or among apple or cantaloupe sized rocks.

These are freestone mountain streams that get a lot of winter snow, and have very high-water flows during spring ice-out. Pea-sized gravel gets washed out of entire sections of such rivers. Look at the topo map. If the river goes through an area with a gradual slope, typically a mountain-valley meadow, and the main channel shows signs or meandering, that’s a more promising place to explore than miles of rapidly dropping terrain with fast water.

The next step is to go hiking and trout fishing on the tributary you’ve identified as the one you want to focus on, as soon as regulations allow and water levels drop after spring sun-off. You’ll almost certainly be on streams at elevations above 3,000 feet, and perhaps as high as 6,000 feet, in the Snake drainage.

You might have to go more than once, depending on how much stream you explore. Look at the stream bed as you fish. Make a note of spawning areas. Look for deeper than usual sections of slow-moving water where it is easy for fish to hold near spawning areas, especially the first big holes just downstream of long stretches of spawning beds.

Keep in mind that places that look good might not be holding big bull trout now, but might at some point—these fish are migratory, and might not have arrived, or might have pushed upstream later in the summer.

Spend time looking at promising holes—from an elevated position, if possible. The clear, smooth water of big holes can allow you to spot big fish In the water, and a high percentage of the time I’ve found big bull trout, I’ve seen them before I’ve caught them.

Tackle for Trophy Bull Trout

I have watched trophy bull trout rise to surface feed during heavy insect hatches, but for the most part, big fish feed deep and take big bites. A 2-foot-long bull trout eats a lot of forage fish, and whatever lure or fly you use should reflect that.

I fly fish for these fish, and typically use streamers at least 2 inches long. A high percentage of these have beadheads, because I expect to fish deep. As for patterns and colors, I’ve found bull trout preferences hard to predict. Basically, they eat large forage items, mainly the fry of other fish, but also anything from crawdads to leeches to mice. Leeches and Clouser-type flies are good places to start. Bull trout also prefer flies with a thick body, at least some of the time. Realism seems less critical than size, bulk and general action of the fly in the current.

Most bull trout I’ve caught have taken have hit darker colors: a black leech with a bit of red, for example. Sometimes they like gaudy flies—purple with shiny tinsel. For some reason, flies that have some red, purple, or green in them sometimes draw the attention of bull trout.

In fact, when choosing flies to take on a long hiking/camping trip for bull trout, bring at a least a few flies that are so big and ridiculous that you can’t really “believe any fish would hit that.”

From my observations, I’d say many small fry that are migrating downstream don’t necessary swim downstream head first, unless they are fleeing from danger. During much of their downstream movement, they are facing upstream, and they sort of let the current push them downstream bit by bit, repositioning themselves as they go.

That means when you are streamer fishing for bull trout and you get to the end of a drift and your fly swings below you, don’t think your cast is over and stop paying attention. This is when your fly moves most like a small forage fish, and when you are most likely to get a bite. You should position yourself and cast at holes so that the end of the drift is where you think bull trout might be.

And when they do hit—which might take some time—they hit hard. Once a small, 14-inch bull trout struck my brother’s fly, but the second my brother started to play his fish, huge bull trout rocketed toward the 14-incher, chomped down on it, shot to the end of the pool (bending my brother’s heavy rod in half without slowing down a bit) and spit out the smaller fish. My brother was able to release the 14-inch fish alive, but it had had a very bad day.

If a trophy bull trout will slam an erratically moving 14-inch fish just to kill it, you cannot possibly throw a fly that’s too big. Do, however, check local regulations on hook gap sizes allowed, as many areas have limits on hooks designed to discourage snagging.

Also, bring multiples of any fly you use. You will not be happy if you start catching big fish on a fly, then have one break off, only to find you don’t have another fly like it and are seven miles from the trailhead.

I prefer a streamer with a long shank, in part because it needs to be a big fly and in part because big bull trout have a nasty set of sharp, needle teeth that will cut leader easily.

Perhaps because they are apex predators in their environment, bull trout don’t seem overly line-shy. I go with heavy leader and weight-forward fly line. That line should be cast with a long, sturdy 8- or 9-weight fly rod.

You need a stout rod to land these fish quickly enough that you minimize the stress on them. Also, bring forceps to remove the hook quickly (taking care not to stick your fingers anywhere near the fish’s teeth). Be prepared to release fish quickly once you land them. Briefly lifting the fish out of the water for a photo is generally legal, but be quick and if you are not taking photos, releasing a fish without ever removing it from the water is best.

Bull trout are a threatened species, and big ones are over 10 years old. It’s not just illegal to kill these rare and beautiful fish: You can’t be killing them if you want your kids to have the same chance to catch them that you still have.

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