Re: Graduating from Dry Flys to Nymph
I hope this helps answer your questions
Nymphing, in its simplest definition, is fly fishing using the sub aquatic forms of aquatic insects. In this definition, nymphing is not limited to using the immature stages of mayflies, caddis and stoneflies. It also includes all sub aquatic invertebrates including scuds, worms, snails, leeches. During this FAQ I will use the generic term "nymphs" to refer to these sub aquatic organisms.
In other FAQs I have referred to a continuum of trout behavior. By this I mean that nature does not split up behavior or development into nice little stages for the convenience of fly fishers. We make these distinctions because it is an easy way for us to understand and teach fly fishing. Just as we teach fly casting by separating the pickup, from the back cast, the forward cast, and the lay down; we separate nymphing, from emergers, and dry fly fishing.
Our quarry, the trout, does not make such distinctions. He feeds on the food source that is most available with the least expenditure of energy.
During the hatch he will follow the progression from nymph to emerger to dry as a continuum. I doubt that he gives it any thought at all. He is just eating what is available.
I want you to approach nymphing in the same way. It is just one method in the continuum of fly fishing. We use it when it is appropriate, because that is how the trout are feeding.
This FAQ builds on the other FAQs I have written. I will expect you to have read the FAQs on Basic Fly fishing Equipment, Reading the Water, and Fishing the Dry Fly. If you have not done so, I suggest that you read these FAQs before going any further.
I have divided this FAQ into several major sections. The first section continues my discussion of a systematic approach to fly fishing in the context of nymphing during a hatch. The second discusses presentation and the third discusses fly selection during non-hatch situations.
I want to reemphasize the concept of a continuum of fly fishing. If you remember anything from this FAQ, I want you to remember that the trout will feed on the food source that provides it with the most calories with the least effort. As the hatch progresses, they will shift from one food source to another. When the trout stop feeding on one insect stage and move to another, they do *not* do so in unison. Each individual fish will make the switch at a slightly different time until you find that the fly that was working so well 45 minutes ago is now ineffective. I will show you a system that can monitor these changes so that you can vary your flies and techniques with the trout.
In the Dry Fly FAQ, I introduced the concept of systematic analysis. Since trout feeding activity is a continuum, the analysis you did for the dry fly will also serve you for nymphing. For dry fly fishing we examined the above water evidence for hatch activity by picking flies off of the bushes, in the air or on the water. We then matched our fly patterns to the naturals.
For nymphing we need to know more about the life cycle of the insect that is hatching. Generally the aquatic forms of the insects (nymphs for mayflies and stoneflies, and larva/pupa for caddis and midges) will become active several hours before the emergence. They will come out of their hiding places or their cases and in so doing, they become available to the trout well before the hatch ever begins. The trout will be feeding on the nymphs and larvae/pupae well before you see any rises. How then do we analyze what patterns to use?
There are two methods that I use. The simplest is to arrive at the river several hours before the hatch. You will have determined the time and type of the hatch by doing some preliminary analysis as outlined in the Dry Fly FAQ. Use your sampling net to gather samples from the river bottom and aquatic vegetation *in the location of the hatch*.
This is important since most river systems have many different species of sub aquatic organisms and they are generally specific to water type and bottom structure (the microenvironment). You may have observed fly fishers sampling the nymphs near the edge of the river. Or perhaps you have seen them pick up rocks near the bank. They are sampling the river correctly *only* if the nymphs that are emerging live in those waters. It does little good to sample the river in the wrong areas. If you sampled incorrectly and fish the wrong nymph, it would be analogous to fishing a caddis dry during a mayfly hatch. You will only catch the occasional fish.
One clue you can use to tell if you have collected the right nymph is to inspect the nymph closely. As a mayfly or stonefly nymph matures and it gets close to emerging, the wing pads begin to enlarge. So look for bulging wing pads. You can use the needle that you carry to clean out the eyes of your flies to dissect the wing pads. If there are relatively well developed wings underneath, the nymphs are mature.
The second method is to classify the hatch you will be fishing. This method is especially important during mayfly hatches. This is a daunting task for the beginner but usually, you will meet someone on the stream who will know the *Latin name* of the hatch. This is important since a generic name will often include several different species. Once you know the name of the hatch you can look it up in a book such as "Hatches II" by Caucci and Nastasi.
By knowing the precise species of the hatch, you can learn in what waters the nymphs live, at what times of the year they emerge, their size, shape and coloration. You will find pictures of the adults and the nymphs to match up to the actual stream samples you have taken. This serves a cross check to see if your identification is correct. And you will learn what the mature imago (spinner form) looks like, and when it returns, so you can fish the spinner fall as well as the emergence. Species identification plus a good practical entomology book is the Rosetta stone of fly fishing. It will unlock many of the secrets of successful imitation.
For example, the first major mayfly hatch in my native waters is the
Hendrickson Hatch, Ephemerella subvaria. This is a dark bodied mayfly about size 12 that emerges from the riffle waters of the Prairie River, about 20 miles from my home. So I would need to sample the riffles to find the nymphs, not the quiet pools below where the mayfly duns can gather. To complicate matters, there is often a masking hatch of smaller mayfly size 14 to 16 that emerge at the same time. If you didn't observe this masking hatch, you could easily fish the wrong fly. This masking hatch is Ephemerella rotunda or the Dark Hendrickson. This is an entirely different species which also emerges from the riffles. Because you are an observant fly fisher you would have noticed both nymphs in your sample net. And you would have read about both hatches and their relationship in "Hatches II".
You are not fooled.
Now you have identified the hatch and you know what the nymph looks like.
Using the hatch books, you have a pretty good idea what the emerger looks like. It's time to choose a pattern. Unfortunately, I'm not going to be of much use to you since choosing fly patterns is much like choosing clothing.
What is normal on Sunset Boulevard in LA is not going to play very well in
Fargo, North Dakota. You are better off using the patterns suggested in the hatch books or seeking the advice of veteran fly fishers in your area. Some areas have a killer pattern that seems to work well on their home waters. If you don't have someone you can ask, I would suggest that you try the generic Levis and T-shirt approach. I use the pheasant tail nymph for the smaller mayfly nymphs, the chocolate emerger for the small mayfly emergers and light and dark hare's ear as general patterns for the larger nymphs. The prince nymph works well for the smaller dark stone fly nymphs with the golden stone for its namesake. The Gary Lafontaine series of caddis patterns is generic enough for most of the caddis patterns, but I favor the copper and peacock as my caddis larva/pupa pattern, and I have several favorite caddis emergers including a CDC emerger.
Now let's move on to presentation.
INTRODUCTION - NYMPHING IS BAIT FISHING WITH AN ARTIFICIAL:
Nymphing is considered by beginning fly fishers as an expert form of fly fishing. Yet for many of you, who are making the change from spin fishing, it should be the most familiar form of fly fishing. Most spin fishers began as bait fishers. If you were any good at it, you learned some of the skills necessary for successful nymphing.
A good bait fisher reads the water and judges where the fish are likely to be holding. He knows that he must present his bait drag free, and he knows how the various obstructions in the river can affect the drift of his bait.
If you are a beginner at this, you might want to check out the FAQs on Reading the Water and Line Mending. Once you have identified where the fish should be holding, you cast your bait upstream so that it will drift down naturally into the lie. All the while, you took up the line as the bait drifted back to you. You looked for the subtle twitch in the line or the bounce of the rod tip that told you the fish had taken the bait. You gave him time to take the bait, struck, and you had another fish on.
Well nymphing is something like that. You will need all your skills at reading the water. Instead of bait, we will be using artificials, so we need to learn some new skills of fly selection and presentation. The thick fly line we use causes a big problem. It is more water resistant than monofilament so you will need to learn a new skill called mending, which compensates for the extra drag of the fly line on the water. And finally, you need to learn how to detect the strike so that you can hook the fish just as he inhales the fly.
With live bait, the fish will hold it in his mouth until you decide to strike. However, with an artificial, the fish will spit it out as soon as he finds out it is not natural. The take will be subtle, so you have to become better at strike detection. These with line mending are the most difficult skills to learn in nymphing, and what gives it a reputation as a difficult form of fishing.
Well let's start turning you into a nymph fisher.
SETTING UP YOUR TACKLE:
The fly rod should be at least 8 1/2 foot and I would recommend a 9 foot rod as probably the best all around rod. The longer rod helps you when mending line and keeping line off the water to reduce drag. The line weight should be heavy enough to cast the nymphs that you will be using and generally a 5 to 6 weight is a good compromise. If you will be using large patterns, a two rod set up with a 5 weight and a 7 weight will cover most fishing situations. The rod should have a relatively quick tip which is important for nymphing since the rod tip must transmit your strike to the line immediately. A quick rod tip also makes line mending easier since you can move line with just the flick of your wrist. If you use a soft action rod for your dry fly fishing it will hinder you somewhat in nymphing.
I use the same rod for nymphing as I do for dry fly fishing. I use a 9 foot
5 weight Sage RPL. This is a progressive action rod which works well for me.
I use a floating line almost exclusively. It is the ideal line to start with since it is easily mended. You can almost always fish the entire hatch from nymph to emerger to dry without switching lines. I reserve sink tip and sinking lines for streamer fishing, when nymphing in very deep pools and runs, or for stillwater fishing. Unless you are using the Brooks method, sinking lines are extremely difficult to mend adequately because much of the line is under water and cannot be mended.
Nymphs can be tied weighted or unweighted. I use Gary Borger's system of nymphing and use unweighted nymphs. There are several reasons for this. An unweighted nymph is more versatile since it can be fished at any level by adding the appropriate split shop to the leader. It can even be fished in the film as a "floating nymph". Weighting the nymph by incorporating lead into the pattern must be done correctly. If the nymph is incorrectly weighted it will ride upside down in the water. This is why many weighted nymphs are tied "in the round". They are impressionistic and symmetrical without a top or bottom side.
Bead head nymphs have become very popular, and they are the only weighted patterns that I carry. They are tied with a heavy metal bead at their head and this causes them to sink rapidly after they hit the water. However, you can get the same effect by putting a bead on your tippet before tying in an unweighted nymph. The bead will slide down the leader and come to lie next to the head of the fly. So make sure you carry an assortment of beads in addition to micro-shot.
You will need a proper assortment of micro-shot. I'm not talking about the size B or BB split shot that you can buy at any tackle shop. Micro-shot are especially made for fly fishing and usually come in a round container holding 4 to 6 different sized shot, the smallest of which is only about 2 mm. in diameter. For waters that have a ban on lead, these shot are also made in a nontoxic formula which cost about as much as if they were made with gold. Note that in some states or fishing areas added weights are not allowed, so in these areas your only option may be to use weighted flies and/or sink tip lines.
You can use the same leader for nymphing as you do for your dry fly fishing. I generally use a 9 foot leader tapered to a 5X tippet. One variation is to use a high visibility monofilament for the first section of the leader. Red Amnesia monofilament manufactured by Sunset can be used as the link between your fly line and leader. It can give you a slight edge in strike detection by making your leader more visible.
If it can be said that any one development helped make nymphing easier, it would be strike indicators. In their simplest form they are essentially a small float placed on the leader that telegraphs when a fish inhales the fly. There are many different types of strike indicators but the all have several qualities in common. They must have high visibility, flotation and an easy method of placement on the line.
I use three types of strike indicators for my nymphing. I use hard foam indicators that is aerodynamic and has a central core that the leader goes through. It is fixed to the line by a toothpick that is jammed into the core. I use this indicator when I am long line nymphing because its aerodynamic shape allows longer casts than the yarn type of indicators.
Instead of buying the specially made indicators for fly fishing, I purchase
"walleye floats" that are manufactured to float leeches and crawlers just off the bottom. They sell for about 10 for $2.00.
The second is a yarn indicator that is made by tying a piece of cord or yarn onto the leader with a slip knot. The cord is fluffed out so that it forms a big fuzz ball which is then treated with fly floatant. The indicators can be made any size by varying the thickness of the cord you use and how much you cut down the fluff. It is probably the most sensitive indicator because its low mass telegraphs even the most subtle take. When tied very small so that it is a 1/4" ball, it falls gently to the water and can be used when emerger or dry fly fishing. Its disadvantages are that in the larger sizes it affects your casting, and on windy days it will act as a sail and actually pulls the nymph the way the wind is blowing. I use macramé cord for the larger of these indicators and tow yarn to make the smaller indicators.
The third indicator is made by Loon Outdoors and is called Biostrike. It is a biodegradable putty that can be put anywhere on your leader. You can put as little or as much as you want to vary the amount of flotation. It comes in several colors so you can use two different colors and two indicators to help you tell the relative alignment of your leader. When spread thinly on the leader or placed in small amounts on the leader knots, it will make your leader more visible under the water. It can be reused by removing it and putting it back into its container. It is a must have piece of equipment.
Although the main purpose for an indicator is to telegraph a strike, it has many other uses. If the trout are holding above a weed bed, the indicator position can be adjusted so that the fly is suspended just above the level of the weeds. It is used as a float to suspend the fly at the level of the fish.
When fishing with small flies or emergers that are difficult to see, a small yarn indicator can help you to judge the position of the fly. If you can't see the fly, you cannot tell when there is drag. It is often hard to tell when the rise is to your fly or a natural. The indicator is used as a substitute for the fly. When the indicator drags, pick up and recast. Plan your line mends so that the indicator floats drag free. A two indicator system can work well in these situations. You can monitor the "separation" between the two indicators to tell you when the leader is about to become tight between the indicators and therefore when drag is about to occur.
Most neophytes do not recognize when they have a strike. Remember that a trout can mouth and get rid of a fly in about a second. Any delay and you will be striking well after the trout has already released the fly.
Most beginning nymph fishers take the bobber analogy too literally. They expect the indicator to go under water or jump upstream. If this happens great, but many takes are very subtle, much like the sipping of a spinner.
Examples are a slight hesitation in the indicator drift, an indicator that is lying on its side becoming upright or an upright indicator which lies down, a slight slowing of the drift, and the indicator staying in one place when it should be moving. Chuck Rizzuto has a saying about nymphing on the San Juan that rings true. He says if you strike 1000 times a day, you will catch fish. So if you see any slight hesitation or movement of the indicator, strike.
One tip is to use floating debris next to your indicator to gauge whether you have a strike and if you have a drag free float. Some rivers such as the San Juan have a lot of floating debris. Use it to compare with the float of your indicator. They should float at the same speed and keep the same distance apart. If not, then you have drag. If the indicator changes its position to the debris more suddenly, you have a take or a snag.
Last year I fished with Chuck Rizzuto, he taught several beginners how to nymph. On one occasion, he told his student to cast just behind a rock. The cast was made and the indicator just stayed behind the rock. Chuck told him to strike and he had a fish. When Chuck was asked how he knew a fish had taken the nymph, he said that the indicator and nymph should have been washed out just like the surface debris. The fact that it stayed behind the rock meant that a fish had taken it just after the cast.
Most neophytes also strike too hard. Just lift the rod firmly just like you are picking up for a cast. You don't need to jerk the nymph from the water.
If you have the bottom then you can just pull it loose and recast. If you have a snag, you won't drive the hook too deeply.
THE MULTIPLE FLY SETUPS:
Most fly fishers use a single nymph setup. The nymph is tied to the end of the leader. If you need added weight, it is placed about 12" above the nymph. The rule of thumb for the placement of the strike indicator is that it should be above the fly about twice the depth of the water you are fishing. This works well for moderate flows but if the flow is faster, you will need to place the indicator higher and if the flow is slower, the spacing is less. You adjust the indicator until the fly occasionally bumps the bottom. This assures you that the fly is riding at the level of the fish.
I often use a two fly setup when fishing in a pre-hatch situation. As stated above, all the trout do not switch their feeding from nymph to emerger simultaneously. This switch is a population based phenomena with some trout making the switch before others. If you fish just one fly, you will be excluding the fish that have switched to the emerger. When you make the switch to the emerger, you are excluding the fish that are still feeding on the nymph. The solution is to fish both the nymph and the emerger is the two fly setup.
In the two fly setup, the nymph should be the point fly with the split shop 12" above the nymph. This keeps the nymph on the bottom where it normally is. The emerger is tied 18-24" above the nymph. This allows the emerger to be in the mid-current just as it should be. To rig up, I first tie the emerger to the end of my leader. I then get some tippet material allowing enough extra length for the knots I will make. If the emerger is size 14 or larger, I will tie the tippet to the bend of the hook. If the emerger is size 16 or smaller, I tie the tippet to the eye of the emerger. In this case the emerger will hang at a right angle to the leader. The nymph is tied to the end of the tippet and the split shot place between the two flies.
This rig is slightly harder to cast than the one fly setup but since the flies are in line rather than off droppers, you won't get the tangles that the dropper system causes. You will find that the fish will initially hit the nymph more than the emerger, but then they will switch over to the emerger. When that happens, you may notice some surface activity with rising fish. They are probably taking the emergers subsurface rather than the dries. It may be time to change to a one fly set up. When you stop getting hits on the deep emerger, take off the split shot and fish the emerger in the film. You can also go to another two fly set up using the emerger as the point fly fished in the film and a dry fly as the second fly. In this case the dry fly also acts as a strike indicator.
Although this is a nymphing FAQ, the sequence above is a common scenario and illustrates how analytical fly fishing allows us to follow the hatch as it progresses. We can fish the entire hatch from bottom to top letting the trout tell us when to change flies. Of course the situation can be complicated by multiple hatches or sequential hatches. In these situations choose representative flies from each hatch so that you will know when to switch from one insect to the other.
Although I have made reference to fishing the entire hatch from bottom to top, most of the trout feed within a foot of the bottom or a foot from the surface. These are the areas with the highest concentration of food during the hatch. The bottom is where all the nymphs must arise from and the surface film is where most emergers must hesitate before they can hatch and take flight. These are the two areas that we must concentrate our fishing efforts.
Most nymphs should be fished drag free. This creates a big problem for nymph fishers. Getting a drag free float is technically the hardest part of nymphing in my opinion. Unlike dry fly fishing where the differential currents are on a two dimensional surface before our eyes; the currents that we must deal with in nymphing are three dimensional, underwater and invisible to us.
Because of frictional forces, the water at the surface will move the fastest.
As we move deeper and near the bottom the water flows slower due to the friction against the river bottom and boulders. Since the fly line and leader must travel through this water column, there is virtually always drag by the strike indicator and the fly line on the fly. Our task is to minimize the effects of this drag so that the fly is carried along at exactly the same speed as the water it is in.
THE SOLUTION - SHORT LINE NYMPHING:
This is the most common nymphing technique that is sometimes called "high sticking" because of the rod elevation that is the hallmark of this technique. Since drag is caused by the faster flow of the fly line and strike indicator on the surface versus the slower flow near the bottom, we can minimize the drag by starting the float with the line and indicator upstream of the fly. This is similar to an in the air mend for a floating fly except that the mend is created through the water column. If we can cast so that the fly enters the water downstream of the indicator, we have created a drag free float until the indicator catches up to the fly and starts pulling it downstream.
To accomplish this we perform a "tuck" cast. A tuck cast is essentially a curve cast in the vertical plane. When you make a normal cast, the loop of the forward cast is *above* the level of the fly line. When there is a weighted nymph on the end of the leader and you add more power, the extra energy flips the nymph and leader over so that the loop is now *under* the level of the line and the fly bounces back to you *under* the leader. The tuck cast is an overpowered forward cast done with finesse so that just the right amount of extra energy is added forcing the leader and fly to tuck under the fly line. When you make this cast upstream, it will cause the fly to enter the water downstream from the leader.
It may seem incongruous to mention "overpowering" and "finesse" to explain the tuck cast but that is really what it is. You have to use just the right amount of excess power to get the tuck you want, and this is a matter of finesse. It is also a matter of practice since it is all done by the "feel" of the cast. This is a cast you must master if you are to become an accomplished nymph fisherman.
In addition to the tuck cast, you must keep your cast shorter than you would use for dry fly fishing. This gives you less line to mend and a closer connection to the fly. As the indicator drifts towards you, you lift up the rod taking up the excess line. This means than you can have the line coming straight out of the water to the rod tip as it comes by you. As you follow the line with your rod lifted high (high sticking), you can get a sense of where the line is going under water, and therefore, how you have to mend to prolong the drift.
The mend is easy to do when the line is vertical. Usually it is just a lift and an upstream mend. The lift straightens the line to the fly and allows the fly to "catch up" with the faster floating line. Since you have all the line off the water, there is no floating portion of the line to create the surface drag. Then you can flip some line upstream to prolong the drift. It is analogous to performing a "tuck cast" in the middle of the drift. As the line continues to drift downstream past you, you feed line into the drift by lowering the rod.
Another solution to the drag problem is to cast directly upstream so that the fly and the line are at least on and in the same relative current flow. You can also cast upstream and slightly across so that the line drifts at or less than a rod's length away from you. Both these techniques minimize the surface cross currents so that you do not have to mend for the surface currents as well as the subsurface currents.
Should you think the fly is dragging underwater at any time during the drift, toss an upstream mend that repositions the indicator back upstream. In so doing, you will temporarily make the fly jump up as the line is repositioned in the water column. This no doubt is an unnatural behavior, but once that temporary disturbance is done, the fly will drift more naturally than if you had not mended.
At the end of the drift, allow the fly to rise to the surface before picking up the line to recast. Sometimes this "lift" of the fly will entice a fish to hit the nymph, which simulates a natural making its way to the surface to hatch. This can be used as a deliberate technique when fishing caddis pupa which rise quickly to the surface during their emergence. You can time the rise so that it occurs in front of a feeding fish causing it to strike.
THE BROOKS METHOD:
The Brooks method is named after Charlie Brooks who developed his technique for taking big trout on big nymphs in heavy water. His method uses a full sinking line tied to a stout short leader of about 4 feet. The leader is short to keep the fly at the bottom with the sinking line. In addition he used weighted flies to keep them on the bottom. This is a heavy duty nymphing system and I would suggest you try it with a single fly rather than with the two fly combo.
The cast is made up and across as with short line nymphing. Take up the slack sinking line as the current brings it back towards you. There is no strike indicator so this system relies on your skill at maintaining contact with the fly but not taking in so much line as to move the fly.
As the entry point of the line into the water gets closer, you raise the rod just as you would in high sticking. But don't raise your hand above the level of your shoulder. Otherwise you will not enough lift left to react to a strike. With the Brooks method there will be a bow in the line and you are using big flies so you will need to strike hard and fast.
As the line comes by you, try to keep the sinking line going vertical into the water. Then as the line passes you, you lower the rod to feed line into the drift just as with short line nymphing. At the end of the drift, allow the pressure of the water to lift the nymph off the bottom. As with short line nymphing this is the point at which you will get many of your strikes so be alert. When the water pressure has lifted the sinking line, you can recast and repeat the process.
It is difficult for a beginner to visualize what is happening to the fly and line under water. We need to make our casts upstream with this method to allow time for the sinking line to come back to us drag free. By taking up the line as it returns toward us, we minimize the drag and allow the fly and line to sink through the deep water to the bottom. Therefore, the strikes will not come until the line is at the bottom where the fish are. Once the line reaches the bottom, it is riding in a current seam that is much slower than the water above it. The portion of the line that rises up to our rod is pushed by this faster current into a curve. We must try to keep that curve as straight as possible but not so straight that we pull the fly towards us. And we cannot let the line balloon behind us either; otherwise the faster current at the surface will pull the fly along. This balancing act requires a skilled hand, and that is why the Brooks method is not often used these days. But for those who are capable, it reaches and catches fish that cannot be reached by the standard short line method.
The downstream or down and across cast is a technique often used by the traditional wet fly fisherman. It is a technique that we can borrow for nymphing as well.
While most nymphing techniques attempt a drag free float, the downstream or down and across technique uses drag to imitate an aquatic insect rising to the surface. After the fly is cast, line is fed into the cast to allow the fly to sink drag free. Then the fly is allowed to swing in the current and the current catches the fly line causing the fly to rise to the surface. You can choose the point of the lift by raising the rod.
This process can be repeated several times during the same cast by repeatedly feeding line into the drift followed by raising the rod. This is a particularly effective technique during a caddis hatch and is the same maneuver as the lift of the fly at the end of the short line technique. I have used this technique with midge hatches as well, but I have not found it very effective during mayfly hatches.
As with the Brooks method, most of the time the strike will come when the line is tight and the pupa are rising. Again a strike indicator is not necessary for this method.
LONG LINE NYMPHING:
Sometimes you need to make long casts to reach the fish. The fish may be holding further out, and you simply cannot get into position for short line nymphing. Or often on the popular tail water fisheries, the wadeable areas have been pounded to death by other fishers. Although long line nymphing is a more difficult technique to master, it may pay greater dividends because you will be fishing to trout that have not been worked over.
First you need a long rod, 9 ft is a minimum. Second, if you are going to make long casts, you need a strike indicator system that is compact and aerodynamic. This eliminates the frayed cord or yarn type of strike indicators. You just can't cast these very far because of aerodynamic drag. I use molded foam indicators for this type of fishing, whereas I might use the cord type of indicators for short line nymphing.
You must choose your spots wisely. You cannot efficiently long line nymph all the waters. In rough or choppy waters the indicator bobs up and down and this causes the suspended nymph to bob up and down. This is not very realistic and results in a poor presentation. Also waters with many cross currents are difficult to long line nymph because of the difficulty in mending the line and keeping the drift in a single current seam.
I usually limit myself to smooth flows, a pool or run type of situation. Here the water surface is uniform. The nymph, although suspended by the indicator, does not have any unnatural up and down bobbing motion. Because the current flows are smooth, there is less need for cross current mending.
You want to set the position of the indicator so that the fly will be near the bottom. I place the split shot about 8" to 12" above the fly. You then cast into the current seam that you want to fish. As soon as the fly and indicator hit the water, start making mends by throwing more line into the drift-seam. If the initial cast was too long to flip mend, use roll cast mends to stack the line into the seam. You are trying to fish the seam as if you were standing in the seam with your rod pointed downstream with you stripping line into the drift. As long as you keep stacking line into the seam and the flow in the seam is even, you don't need to worry about cross current drag.
However, there will still be differential drag between the indicator which is on the surface and the fly which is near the bottom. The indicator will usually be moving faster than the fly and dragging it along faster than it should be going. You can help to minimize this, if on your cast, you curved it so that the fly landed downstream of the indicator. (This is essentially what a tuck cast does from the downstream approach)
Eventually the indicator will catch up and pass the nymph and start to cause drag. You can then temporarily lessen the amount of line you stack into the drift which will slow down the indicator, allowing the nymph to catch up or pass the indicator. Then start mending more line. You can do this only once on a long cast because the moment you start to pull the indicator back, the fly line starts to tighten and it will begin to pull the indicator towards you out of the current seam.
What I do is to actually pull back on the line which moves the indicator upstream and repositions it into another seam. It also makes sure that the nymph is now downstream of the indicator, and then I start mending again. Sometimes the fish hits when I pull back because it thinks that the nymph is rising to emerge.
The one problem with long line nymphing is that most of the time there is slack line in the system and you will only hook 1/4 to 1/3 of the strikes you detect with the indicator. But it is a thrill to get a strike since it means that you are mending the line correctly. And besides, you would not be long line nymphing if the short line technique was productive.
Eventually, the fish will migrate from nymphs to emergers. You will find that you are catching most of your fish on the emergers. You will also notice that some fish have started to rise along the current seams in the prime lies. It is time to remove the nymph and fish the emerger just subsurface or in the film.
With the two fly set up; the point fly was the nymph with the split shop in between the two flies. You can easily convert to a subsurface emerger set up by cutting off the nymph tippet from the emerger and removing the strike indicator. Now grease your leader to within 4-6" of the emerger. This will cause your leader to float and will hold the emerger patterns just under the film. If you have a hard time telling the position of your fly, you can use a small yarn strike indicator about the size of a pea to help you locate your fly and to tell when it is dragging.
You may find some of your toughest trout when fishing emerger or subsurface nymphs. This is where the crossover to dry fly techniques can occur. These fish will be holding just below the surface, and if there is no overhead cover, they will be extremely spooky. Their feeding windows will be small and the techniques I discussed in the dry fly FAQ regarding long leaders and downstream approaches may be your only chance to catch these fish.
Although you want to fish the mayfly emergers drag free, caddis emergers and midge emergers can be fished with slight motion to help the trout key on your fly. The added motion will often entice them to strike. Again this is often more easily done with the downstream approach. Time the motion just as the fly reaches the edge of the trout's window.
In a non-hatch situation the nymphing techniques you use are the same as during a hatch. The only change is that your fly selection is not based upon what is about to hatch, but rather on what is available in the river. In these situations it is imperative that you use a sampling net to get an idea of what food sources are available to the fish. You want to match as closely as possible the size, shape and coloration of the nymphs and caddis pupae that you find.
You must also sample the aquatic vegetation for scuds, sow bugs, or other aquatic crustaceans that supply much of the food source of the trout during these non-hatch periods. Your skill at stream sampling for nymphing is just as important as your ability to identify the surface fly for dry fly fishing.
I recommend using the two fly set up since this will double your chances of selecting the correct fly. Usually the trout are feeding opportunistically in this situation, so I would recommend using different types of patterns for the two flies. Rather than two mayfly nymphs, choose a caddis pupa and a mayfly nymph, or perhaps a scud and a nymph. I also recommend making at least one of your patterns large enough to spot from a distance, say at least a size 12. That fly will attract the attention of the trout and then he will also see the smaller companion pattern.
Since you will be fishing blind, I want you to review the Reading the Water
FAQ and use the information there to help you locate the prime lies. You will be fishing the waters in a searching pattern so it makes sense to concentrate on those areas which are likely to hold fish.