Small Flies for Big Trout
You’d think large fish would eat only large flies. But on many Montana streams and rivers, it doesn’t work that way.
This story is featured in Montana Outdoors May–June 2009
It’s late July on the Missouri River. The river is low this time of year, and the current glides over lush weed beds. The brilliant midmorning sun illuminates both the riverbed and several large trout hovering in the slow water near shore. The fish rise again and again to countless tiny mayflies floating on the water’s surface. Hundreds of thousands of these aquatic insects, of the genus Tricorythodes, dance in the air above, forming small clouds over the river. After repeated casts, an angler’s tiny Trico dry fly is finally sipped off the surface by a particularly massive, slow-rising trout. The hooked fish surges into the depths. The fly reel spins. After much shouting and excitement, a landing net is slipped into the water. Once again, as happens often on this and several other famous rivers and streams across western Montana, the old adage “big flies for big fish” is proved wrong.
Steak and peanuts
Trout survive primarily by eating various life stages of aquatic insects. Anglers catch trout by using flies that mimic the different stages: larvae and pupae (imitated by flies generally known as nymphs), emerging adults (flies known as emergers), adults drifting on the surface ready to take flight (duns), and dead adults floating on the water surface (spinners).
Some aquatic insects, such as salmonflies and golden stoneflies, are as large as your thumb. These big bugs require rocky-bottomed rivers and highly oxygenated water, the kind found only in rapids and riffles. At certain times of the year, trout readily take flies imitating these big bugs—the trout’s equivalent of a 32-ounce ribeye. Anglers love these hatches. The flies are easy to see, and presentations don’t have to be delicate or accurate. In fact, the angler isn’t casting to visible trout, but to banks or boulders where fish might lurk. Trout lunge at artificials such as the Madame X or Sofa Pillow like it’s the last insect they’ll ever see. The strikes can be savage, because the water is moving so fast a trout has to rush at the fly to catch it.
It’s a fun way to fish, no question. But it doesn’t last long. These extra-large insects hatch only in fast water, such as the Gallatin and the Madison, and only for a few weeks each year at the end of high water runoff in late spring or early summer. By early July, the big-fly action is ending. Then a completely different type of dry fly fishing begins on certain Montana waters.
I’m talking about the slow tailwater fisheries below dams on rivers such as the Missouri and the Bighorn, as well as the larger spring creeks such as Nelsons and Armstrong. On these waters, rapids are rare, current is slow, and the surface is slick. Lacking a rocky substrate as well as the rapids that mix air into the water, these rivers also lack larger aquatic insects. Instead, their fertile waters produce enormous amounts of smaller bugs such as midges, mayflies, and caddis flies. And for much of the summer, big trout lie in plain sight sipping the tiny insects.
If big flies are like steaks, tiny flies are like peanuts. Though they are still packed with protein, a fish needs to eat many more to stay full. The good news for an angler is that trout eating tiny flies are constantly rising to the surface. The bad news it that fooling these trout—especially big ones over 20 inches—can be extremely difficult.
No need to move
Spring creeks and tailwater fisheries are extremely fertile and hold enormous insect populations. After hatching, the insects collect in eddies and other slow water, which can become nearly blanketed with bugs. Trout here have learned they don’t need to rush after their food: A steady supply is floating overhead as if on a conveyor belt. These fish are observant and deliberate. They have time to look over your fly in the slow flow. That means your fly has to be as tiny as the insect it mimics, and you must employ hair-thin leaders, accurate casts, and stealth.
During a hatch in slow, slick waters, a trout doesn’t need to move more than an inch or two to take a fly off the surface. It finds a spot where it can grab the most food possible with the least effort fighting the current. Like all creatures, trout survive and grow only by consuming more calories than they expend.
The biggest steadily rising trout tend to be in the slowest current. And the slowest currents are usually along the bank. That’s why so many of the big fish I find for my clients are in less than 12 inches of water, just a few feet from shore. Other spots to look for big trout are flats, eddies, and the slow water along inside bends.
These zones may not have the boulders, logs, shade, or overhead cover that hold trout in fast streams. So what do they offer? A life of leisure. All insects coming from upstream are compressed into a shallow water column just a few inches deep. A fat trout can fin near the bottom without wasting energy, rise a few inches through the slow current with minimal effort, slurp a bug, and sink back down. It’s like sitting on the couch with bowls of corn chips, M&Ms, and buffalo wings all within arm’s reach.
Experienced anglers recognize these shallow zones. But beginners splash right through the skinny water, spooking one big fish after another. They assume the lunkers must be deep, never realizing they are standing right where a 20-incher was swimming moments earlier.
The rhythmic rise
To further minimize physical effort, big trout rise to surface insects in a rhythmic pattern, their head and shoulders porpoising or just their snout bobbing at the surface. This feeding pattern is like a hiker’s steady gait. By walking at a constant pace, hikers can travel for hours. But if they stop and start and change speed, the trip is more tiring.
A trout rises in a rhythmic pattern only when the water surface is covered with insects. It doesn’t even need to see a particular insect on the water. It learns that with each rise, a bug will be next to its nose.
Beginners assume these steadily surfacing trout will be easy to catch. After all, the fish are rising like clockwork. But in fact the opposite is true. A trout feeding rhythmically to tiny insects may be focusing on a 4-inch-wide feeding lane in front of its nose. That means you have to cast repeatedly, make exact presentations, and use the most realistic fly pattern possible. Skilled casters commonly place a fly perfectly over a trout a dozen or more times before the fish finally takes it.
And often the take is just luck. The fish doesn’t “go after” the imitation. It just happens to rise and open its mouth the moment the fly arrives.
This type of fishing can be infuriating for some anglers. Either they don’t use the correct imitation, don’t make a perfect presentation, or they spook the trout. It’s incredibly easy to scare a shallow-water trout. The fish dash for deep water when they see a person nearby, feel the wake of a wading angler or a boat, or encounter silt from someone wading upstream. And there’s more: A fly that lands too hard and too close will scare a trout, as will fly drag, repeated presentations of an unnatural-looking fly, and the “grease halo” of a dry fly that has been freshly treated with floatant.
Up or down?
Before you can attend to any of those concerns, however, you need to decide whether you want to cast upstream or downstream to a rising fish. Both approaches can work equally well, but each requires a different technique. The upstream caster comes up from below (downstream of) the fish, moving slowly and quietly to get close. Because the trout is facing upstream, it can’t see the angler. The trick here is to cast with very light leader—from 5X to 7X—and put the fly 1 to 2 feet upstream of the fish. It’s easy to spook a trout from this position if it sees your line and leader repeatedly flying overhead while you false cast. I false cast rapidly off to the side, keeping my rod low to the water. Then, as the trout rises, I zip my cast to a spot upstream of the fish.
This accomplishes several things. The fish is less likely to be spooked by my presentation because it’s now looking through the water “rings” caused by its recent rise. Also, as my fly and leader land, the fish is tipping its head down toward the bottom. A trout moves in the water column by tilting its body slightly up or down and letting the current raise or lower it like wind on an airplane wing. By the time the fish has refocused on the surface and has angled up in its pattern to take the next mouthful, my fly has had time to float to the exact location of the next rise. At least that’s the theory.
Getting above that same fish and casting downstream requires a different strategy. First of all, I don’t cast directly downstream but down and across at about 45 degrees. As the fly is about to land, I cock my wrist to bring the rod tip back and create some slack in the line. Ideally, the fly lands 4 to 5 feet upstream of the trout—far enough so the fish can’t see the fly, leader, and line hit the water. As the fly drifts downstream, I shake out line from my rod to get the longest drift possible. This keeps the fly downstream of the leader, so the trout sees the fly first and isn’t spooked by the leader. The longer drift also means I won’t drag my fly over the fish. Finally, I make sure the fly drifts about an inch to my side of the trout, further decreasing the chance it is spooked by the leader.
I’ve found that the downstream cast works best when I’m wading broad, shallow flats, or when I’m casting from an anchored boat to trout hugging the bank.
ON THE PROWL
Serious fly-fishers know the major species of tiny bugs, as well as when and where they appear. You’ll hear hushed talk like, “I’m gonna hit the Baetis hatch on the ’Horn”; “The Tricos are thick on the Mo”; and “They’re sipping midges over on Nelsons.”
Get in on the action by reading fishing articles, websites, and blogs. Call fly shops. Find out which bugs, patterns, and sizes are working best at the moment, and what times the hatches begin and end (sometimes that changes daily). You don’t need a huge supply of patterns. I catch most of my rising fish on roughly a half-dozen: midges, Parachute Baetis, Parachute Adams, Pale Morning Duns (PMDs), PMD Spinners, smaller caddis imitations, and Parachute Double Tricos—in sizes 18 down to 24.
Fishing to trout in the conditions described here is similar to hunting. You can’t just wade out into the river and start casting. You have to prowl around and search for rising fish. That means stealthily walking the bank while scanning for riseforms, or drifting quietly while scanning ahead for rising fish. Examine every eddy, flat, and bankside shallows until you spot a large feeding trout. You now have a better idea of why that fish is there, what it’s doing, and how to deliver your tiny dry fly into its white gaping mouth.
Neale Streeks is a Missouri River fishing guide and the author of several fly-fishing books, including Small Fly Adventures in the West. He lives in Great Falls.
[ BACK TO TOP ]