Practical and Useful

Practical and Useful

Match That Hatch!

  • By: David Hughes

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JIM SHOLLMEYER PARKED THE DRIFT BOAT AT THE head of a small island in the Bighorn River, stepped out and scanned a side channel for the Blue-Wing Olive hatch that we both hoped would begin soon.
I’m more restless than Jim, so I grabbed my rod and bounded off downstream, along the inside edge of the island, hoping to find something going on elsewhere in the side channel while I waited for the hatch to happen. All I got was some exploration and exercise; I’d already turned and was wending my way back upstream toward Jim when a few faint rise rings appeared on the smooth surface currents between the island and the Montana mainland.
I began edging toward those trout at once, not so much planning to get a hook into one at that instant, rather with the hope that I might get a close gander at exactly what prompted them to begin feeding. Within a few minutes I slipped my aquarium net under a struggling mayfly dun, lifted it out, saw it was size 18 and olive. I knew from previous book study that it was the anticipated BWO, in the broad Baetis complex, but I also knew that didn’t really matter to the trout, because they don’t read the same books I do, and don’t spend a lot of time pondering the Latin names of aquatic insects. They just recognize them as something good to eat, rise up and sip them, and just often enough make mistakes about adequate imitations.
Because the hatch was just getting under way, and I suspected the trout were seeing as many duns struggling to escape their shucks as they were those that were already free of it, I selected a size 18 Olive Sparkle Dun. With its trailing Antron shuck, it’s a dressing that trout might easily mistake for either an emerger or a fully-formed dun.
My tippet was 5X and fairly long, but I deemed the surface so smooth, and those Bighorn trout so heavily pestered, that I’d better fine it down. So I nipped the 5X back to a foot and knotted three feet of 6X to the end of it. I knew the fragile tippet greatly enlarged my chances of hooking trout, while at the same time greatly diminished my odds of landing them. It was a fair enough trade for me.
I slipped into position on an individual fish, just a bit upstream from straight across from it, and began showing that dry fly to it with cross-stream reach casts. It took some time to get the range right, to place the fly close enough to the trout’s feeding lane, to feed enough slack into the drift so the fly came into sight floating freely enough . . . by then the trout had seen the fly misfired so often that it was forewarned before I got the presentation right. But I’d worked out some kinks. Two spooked trout later, I managed to get everything sufficiently together on the first cast so that a nice nose poked out and went down with that little fly embraced. I landed the fish. It was big enough to make it all an adventure on that flimsy 6X tippet.
I went on to catch several more trout, all nice fish, before the hatch trickled to an end a couple of hours later. Acceptance always came in about that same ratio: two or three trout put down for every one successfully brought up. Jim, still fishing up by the parked boat, did quite a bit better. He always does.

THAT BWO HATCH WAS COMMON-place in some ways. But in another way the hatch was instructive. Fishing it successfully required the same simple steps it takes to match any hatch, anywhere. The process might seem complex, and it can be if you want. But you can also reduce it to the four quick steps I went through when the BWOs first began emerging on that Bighorn River side channel.
The first step is to observe the insect on which trout are feeding. It won’t hurt if you learn its Latin name, unless you trot to shore at once and look it up in a book while the hatch is happening; do that sort of study later. For the moment all you need is to collect one and note the same things that please the trout: the insect’s size, shape and color. An aquarium net will help corral a specimen. A small magnifying glass will enforce a closer look. Neither is necessary, but the two can provide an excellent extension of your on-stream education without taking up much room in your vest or pack.
The second step is to select an imitation. It never needs to be exact—there is no such thing short of impaling an actual insect on a hook. It should, however, be the same size, as near as you can get in shape, and if not the right color, at least the right shade. In my experience, insect species vary so much in color from stream to stream, even from place to place in the same stream, and ultimately from one individual to another in the same hatch, that it’s adequate to average color out (see Practical & Useful, Winter 2014: “Big Mission for a Small Fly Box”). It wouldn’t be wise to make a trip to any river without consulting a local fly shop; they’ll greatly condense steps one and two above for you. But you should still make your own observations when aquatic insects begin to emerge, and noses begin to poke out to end those tiny lives.
The third step, once you’ve observed the insect and selected an imitation, is to adjust your rigging to suit the situation at hand. If the insect on which trout begin feeding is a size 6 salmonfly adult, you’ll need to trim your leader back to 3X. If you’re fishing a size 18 BWO in a riffle, two feet of 5X might be long and fine enough. If you’re fishing smooth water, such as our Bighorn back-channel, then three to four feet of fine tippet will improve your odds so dramatically that you should automatically change it out whenever it gets shorter than two feet. This, I’m sad to say, is the single most violated rule in all of hatch-matching. Too many folks, myself too often included, frantically change flies when they should patiently lengthen tippets.
The fourth and final step in matching a hatch is showing the trout your fly with the correct presentation. This is naturally related to the type of water over which you’re casting. If it’s a riffle or rough run, then the trout’s sight window on the surface will be broken, and you can get away with an upstream presentation. But it will always be better if you can get off at least slightly to one side and show trout your fly without tossing the line and leader right over their heads. If the surface is somewhat smoother, then you’ll increase your chances by taking a position across from the trout, and presenting your fly with the cross-stream reach cast. If the water flattens out, then it might be necessary to take a position upstream, presenting with a downstream wiggle cast.
The important idea is to show the fly to the trout first, ahead of the line and leader, and floating freely on the surface, as if it’s unattached, just like a natural insect. That might necessitate some minor mending and tending of the drift: upstream flips of the line to prevent early drag, or feeding slack into the back end of the line to lengthen the free float out at the distal end, where you hope a trout will be fooled by your dry fly. A little bit of experience, accompanied by close observation of what is really going on out there where your drifting fly intersects with rising trout, will go a long way toward telling you what to do to make that drag-free presentation.
Always follow the same four steps, whether you’re a beginner or you’ve done it a million times. The more you do it, the more intuitive it becomes and the less you have to think about it. A guide would do it without even knowing he or she’d done it.
If there is a fifth step, it’s employed when all of the above fails to fool the trout. This is no rare occurrence, even for the greatest anglers. When it does, it’s best simply to run through the same set of steps, perhaps with a bit of sharper observation added. First, make sure trout are feeding on what you think they are; they might be taking an emerger when you think they’re taking a dun. Second, make sure your imitation is the right size, shape and color. Now that you’re fishing, observe the posture with which the fly floats on the water, out there among the naturals that are afloat on the same water. If your fly looks like the perfect imitation when held in your hand, but floats on the water with an entirely different appearance, the trout will almost certainly refuse it. Try another pattern style.
Third, check your tippet to see if it’s still three feet long, and fine enough for the water you’re fishing. If you have any doubt, nip back the existing tippet and tie on three feet of tippet one diameter finer. Finally, change your position and presentation, with an eye to showing the trout a fly that floats like a natural might, as if unattached to anything else in the world.
As you become more experienced, this is all done quickly and without much conscious thought. You observe the insect, select a reliable imitation, check and refresh the tippet, tie the fly on and move into position for the appropriate presentation. If you get nothing but refusals, you reassess the situation using the same set of steps, and soon enough you’ve got it worked out and are into trout.
The idea is to shift it all to habit, so that soon you’re out there successfully matching hatches with minimal thought about what you’re doing to make all that excitement happen.

Dave is author of Pocketguide to Western Hatches and Trout Flies.

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