Situational Nymphing

by Danie Erasmus

Anglers are creatures of habitat and once they find something that works for them, they tend to stick with it. Nymphing is no exception and many anglers use the nymphing method that gives them the most confidence on the water, even in situations when a different method is better suited to the conditions. Nymphing is not a one size fits all approach, and part of the fun is learning the different nymphing methods and their suitability to changing fishing conditions. Recognize that the fishing situation always changes on the river, not just as the season goes along, but during the day as you encounter different conditions.

The two biggest factors when nymphing are the water conditions and trout food. The water dictates how you are going to fish as the river may be high, dirty, low or clear. You are also not going to fish different types of water the same. Riffles, runs, pools, glides and riffly-runs all require a different approach. Adjust to the water conditions by adjusting your nymphing method as fishing only one method will make it challenging.

The availability of aquatic insects and their behaviour directly influence your fly choice and how you plan to present them to the fish. In the case of nymphing you are imitating insect nymphs and larvae, and in tactical nymphing an angler reacts to the conditions on the river by employing the best approach. This means switching between nymphing methods to fish good water well.

Do not be afraid to switch between methods

Over the last 30 years nymphing has evolved to the point where anglers are very effective in getting the fly down to where the fish are. Anglers use flies that sink quickly in combination with leader systems that facilitate a quick decent. Technological advances in fly rod construction have produced fly rods and fly-lines dedicated to nymph fishing. Today we have a greater variety of nymphing methods to fish large and small nymphs in all types of water, from shallow and slow to fast turbulent sections.

Incorporate as many different nymphing methods into your arsenal. Learn to master indicator nymphing, high-sticking, Czech/Polish nymphing, French and Spanish nymphing. They all shine when used in the right situation.

Indicator nymphing is versatile as it is very effective in a number of different situations. It is effective when fishing from drift boats, but you can also fish it from shore. You can fish it in all types of water, and you can fish in close near you or further away.

Short-line nymphing methods, such as high-sticking and Czech/Polish nymphing with their short leaders, are well suited to fish more turbulent water including faster moving runs, pocket water, and riffles. Czech/Polish nymphing allow you to fish your flies below the rod tip, and with a taught leader you have direct contact with the flies allowing for effective detection of bites. On the other hand, with high-sticking, you can extend your fishing radius a little further, but you may not have the same direct contact to the flies.

Long-line nymphing methods are ideal to fish low and clear water. If you are fishing upstream employ French nymphing with its 20-foot plus leader and small nymphs. Spanish nymphing uses a similar length leader as French nymphing, but you fish slightly deeper water with heavier flies by casting across the current.

Many North American anglers fish what they call Euro nymphing, but most are actually combining, perhaps unintentionally, high-sticking with either Czech nymphing or Spanish nymphing. There is nothing wrong with it and this fusion of two methods works and is just part of the natural evolution of fly-fishing. These hybrid versions of high-sticking with Czech nymphing (short-line approach) and high-sticking with Spanish nymphing (long-line approach) are extremely versatile. Many anglers use these methods with a sighter to detect strikes. A sighter is a piece of leader material that is usually bright orange and yellow.

These methods were developed over a number of years in different parts of the world in different contexts of regulations, fishing conditions, and fishing cultures. They are still around because they are all effective in catching fish. Incorporate as many of these methods into your own arsenal as they all have their advantages in different situations. The trick is to recognize which method to use under what situation.

Listen to the river

To fish good holding water well, listen to the river to determine which nymphing method to use. On a day of fishing it is possible to switch between several nymphing methods as you encounter different types of water. As the season progresses water levels fluctuate, changing the type of water. It is entirely possible to nymph a section of water by high-sticking it earlier in the year, but as water levels change, fishing conditions change to the point that a long-line nymphing method becomes the better approach.

Fish are very aware of the water conditions. In low clear water fish are going to be cautious. To fool them you need to fish from further away, using smaller flies, longer leaders, and fine diameter tippet. The same holds true for heavily fished waters. In conditions where the water is more turbulent or coloured, you can get closer to the fish with a nymphing method that is not subtle in presentation.

Make sure your leader setup and flies match the type of water and conditions on the river. Carry leader setups for both short-line and long-line nymphing methods, but changing in between these leaders can be a nuisance. Although many anglers change leaders using the loop-to-loop connection system, instead try using the loop on your fly-line and attach your leader with a non-slip loop knot. When changing leaders, just cut the leader off and tie a new leader on with the same knot. This is much faster and convenient than the loop-to-loop threading approach.

Know your food pairing

It can be very difficult to understand the different insect species in a river, and how to use that knowledge to improve your fishing. Some species can only be imitated with a specific fly, but in other instances several species can all be imitated with a single fly. The best thing to do is to keep it simple.

Across the continent there are literally hundreds of different stonefly species. Many of these though, behave and look similar to one another. This means that you can minimize your stonefly imitations to a few different flies. The major stoneflies nymphs to imitate are the giant black stoneflies (aka salmonflies in the west), golden stoneflies (aka common stoneflies), and yellow sally nymphs (aka Stripetails or Springtails.

The larger stoneflies such as the giant black stoneflies and golden stoneflies are more effectively fished in faster moving water of riffles, pocket water and runs. Short-line methods such as Czech nymphing or high-sticking are good choices to fish these larger stoneflies. You can also use these larger stonefly patterns as anchor flies in multi-fly rigs. These heavy anchors also allow you to present smaller flies in water that would otherwise be hard to fish.

As a medium size stonefly, yellow sally nymphs are effectively imitated using long-line methods such as Spanish nymphing in shallow or slow water next to a seam with fast moving water. In this type of water, yellow sally nymphs are ideal as point flies, with mayfly, caddis or smaller stonefly imitations as dropper flies.

There are a number of smaller stonefly species that occupy rivers in high numbers. Generally these smaller stonefly nymphs look very similar to one another and are imitated with size 16 flies or smaller. They are slender in shape and are found in shades of brown, olive and gray. Nymph imitations of these stoneflies can easily double as mayflies and vice versa. As they are small in size you are limited to slower and shallower water to fish them effectively, unless they are part of a multi-fly rig with heavy nymphs.

Be aware that there are some regional stoneflies that can be important, like the Skwala on some rivers in the West. This means you may have to tailor your flies a little to the local food. However, in general simplify your stoneflies as it also helps you focus on which nymphing method to use.

Imitating mayfly nymphs is a little more complex than stonefly nymphs. Mayfly nymphs evolved into different morphology types that allow them to occupy a variety of habitats in streams. On most streams, focus on imitating three of the four morphology types: clingers, crawlers and swimmer nymphs. Each morphology type is distinct in shape and each type represents many species of mayflies, but all are mostly shades and combinations of brown, olive, gray and black.

Fish clinger and crawler nymphs the same way as they often occupy the same habitat. Clinger nymphs have flattened bodies and wide flat heads, making them streamlined to reduce resistance in the fast currents of riffles and runs. Crawler nymphs adapted differently to the conditions, with more robust and stout-looking legs and bodies, they crawl and cling to rocks avoiding being swept away by the current in riffles and runs. To imitate these two morphology types, tie imitations to be wide and stout, which allows more weight in the fly. Use oversized beads and some extra lead wire in the body to give a wide profile. This added weight allows you to fish clinger and crawler nymph imitations with one of the short-line nymphing methods in faster water. In slower water, along the seams of fast moving water, take a Spanish nymphing approach in getting these nymphs down to the fish.

Swimmer nymphs on the other hand can swim in both fast- and slow-moving water with very little effort. They often look like miniature fish fry darting among the rocks. Swimmers occupy a wide variety of habitats, from moderately flowing riffles and runs, to the slow water of pools and back eddies. These nymphs tend to be more slender in shape and that does not allow for a lot of weight in the fly. Swimmer mayfly nymph imitations are a good addition in multi-fly rigs as droppers, or fish them with the long-line nymph methods in shallow water.

Caddisfly larvae can be divided into three general groups: net-spinning, free-living, and case-maker larvae. Trout feed on all three caddis larvae groups but if you walk through fly shop you will not see many flies imitating case-maker larvae, but you will see a lot of caddis larval imitations without cases. This is due to the fact that net-spinning and free-living caddis larvae consistently have large populations in many streams, and make up a large portion of a trout's diet.

Given the grub-like appearance of caddisfly larvae, you can add a lot of weight to flies imitating them. In general, net-spinning and free-living caddisfly larvae have brown-gray heads, legs and thorax with abdomens that are olive to bright green. Imitations of these are fished with great effectiveness in a variety of water conditions and water types such as riffles and runs. Given these types of water, it is no coincidence that Czech/Polish nymphing goes hand-in-hand with caddisfly larvae imitations. Much of the development of these short-line methods happened along-side the development of flies that started out imitating caddisfly larvae.

Nymphing just before the hatch

Heat (energy) is especially important in an aquatic system. The rate at which the temperature is increasing and the length of a warming period directly influence the metabolism of nymphs.

In years when winter ends earlier and spring warms up sooner, hatches shift forward by a week or two. The warmer temperatures allow nymphs to be more active, and mature faster, and the opposite is true when old man winter stays around longer.

Some of the best success with nymphing happens when the insect nymphs become the most active, which is usually just before they hatch. Many of these insect nymphs migrate to shallow water before hatching and trout key in on this. You can find out which nymphs are about to hatch by doing a quick kicknet sampling in shallow water. This helps narrow down which flies to start fishing.

All stoneflies have the same emergence strategy. When ready to transform into the winged terrestrial adults, the mature nymphs migrate to shore to emerge on land, with many nymphs staging in shallow water. During these migrations and staging, nymphs expose themselves to predation by fish.

A good strategy is to fish the nymph stage the week or so leading up to a specific hatch. Knowing when hatches take place is important. The giant black stoneflies emerge in May to June, followed by yellow sally nymphs and golden stoneflies in June to July. You can also fish semivoltine stonefly nymphs (salmonflies and golden stoneflies) year-round, but their populations are more concentrated into specific parts of the stream in the time leading up to their emergence.

Mayfly nymphs become very active before they hatch, and in many species the nymphs migrate to slower and shallower water. Many mayflies hatch from May to July, followed by a second round of hatches in August to September by some species. Mayflies have more diversity in their hatching strategy compared to stoneflies. The majority of mayflies (such as Western Green Drakes, PMDs, PEDs, BWOs, Flavs, and Mahogany Duns) hatch on the water surface. Among these mayflies, some nymphs may swim to the surface to hatch, and others the duns hatch at the bottom and then swim to the surface. A few mayflies, such as Gray Drakes and Brown Duns, crawl out onto shore to hatch. Regardless of the way mayflies hatch, trout see the highest concentrations of the mature nymphs in the time leading up to the hatch.

In caddisflies, you do not see the accumulation of highly active larvae just before the hatch. Instead caddisfly larvae build a cocoon in which they pupate for up to eight weeks. From these cocoons pupae emerge to become adult caddis. These emerging pupae are better presented with wetfly methods rather than nymphing methods. To present the emerging pupae, cast across the current and let the flies swing to imitate the rising pupae.

Behavioural drifts

Nymphs migrate or disperse in streams through a process called behavioural drift, which is different from sporadic washing of nymphs off the bottom or when they migrate to hatch. Behavioural drifts are deliberate and performed by many aquatic insects to find new habitat. When ready to do so, the nymphs let go of the bottom and drift downstream, resulting in a dramatic increase of nymphs suspended in water column, especially over riffles. These drifts are only a few metres at a time, but insects may perform a stepwise drift to find new habitat. Trout respond to these drifts by heavy feeding, a time an angler cannot miss. To enhance your nymphing, it is important to know which insects dominate these drifts and when these drifts take place.

Behavioural drifts peak in the spring and summer and are also influenced by light conditions. Although behavioural drifts can take place anytime, the major drifts take place during sunset or just after, and the second peak is just before sun up. Research has also shown that these drifts occur less during a full moon.

Chironomid larvae make up the bulk of behavioural drifts, as they can be as much as 40% of the organisms in the drift. Many species of mayflies disperse in streams through these drifts as well, especially swimmer mayfly nymphs in the Beatis Genus. Other mayflies such as clinger nymphs are seldom found in dispersal drifts samples. Stoneflies such the large black stoneflies often curl up when they drift downstream. Whereas some of the smaller species tend to be motionless in the water column while drifting. Predators, like the golden stoneflies, tend not to disperse to new habitat by drifting. Many caddisflies also partake in drifts, especially free-living and net-spinning larvae. Larvae building cases from plant material also perform these drifts, but more controlled using a silk rope anchored to the bottom. Two caddisfly larvae common in the drift are Hydropsyche larvae, and Grannom larvae with their chimney cases. Caddis larvae who build cases from small stones tend not to take part in these drifts except when they are between cases.

Targeting the behavioural drift when nymphing can be very effective. It is also a good opportunity to fish small flies with longer leaders as the insect nymphs are suspended slightly higher up in the water column, and your flies do not need to be right at the bottom. You still need to be close but it is not as critical. Employ leader setups similar to Spanish nymphing using ten-foot or longer rods.

The different nymphing methods have their strengths and weaknesses. Recognize these and employ the appropriate method when the right situation arises. Recent literature on nymphing has been focusing on the most effective leader setups and flies. Not enough time is spent talking spent about using a nymphing method that is the most appropriate with the combination of water conditions, type of water, type of food, and the food's behaviour. Integrate these aspects into your nymphing to become more tactical in your approach.

First published in                          Spring 2019