As a flyfisher with a thing for imitation, Nick wonders if that’s a quality or a quirk?

Much of the lore and literature relating to flyfishing for trout revolves around them feeding on specific insects, and the need to imitate that food to catch them. But how much of this is borne of necessity, and how much is just romance and tradition, or even dogma?

Like many of life’s important questions, maybe the answer (as Peter Hayes often tells me), is, ‘it depends’. For a start, it’s worth looking at what constitutes imitation; and how, where and when this might affect fishing success.

Defining imitation

Firstly, I need to clarify what I mean by imitation. It goes without saying that if a trout tries to eat your fly – any fly – it has been fooled enough to mistake it for food. In that sense, your fly has ‘imitated’ food. However, in flyfishing terminology and philosophy, ‘imitation’ has a narrower definition. By one line of thinking, we can broadly categorise flies (and the associated approach to fishing) into three groups: imitative, impressionistic, and attractor.

Imitative flies

The focus of this article is imitative flies. An imitative fly is one that is used to specifically represent a particular food – often an insect – which the trout feeds on, even down to the lifecycle stage. This approach can be further split into two.

• The classic ‘matching the hatch’ to catch what we consider to be selective fish; trout which the evidence suggests are feeding exclusively on a specific insect during a hatch or a ‘fall’. The imitation we choose is often further refined to the lifecycle stage of the insect (for example, pupa, spent spinner, etc.).
• We don’t actually observe a dominant hatch, but we still try our best to represent a specific insect which we believe is likely to be on the trout’s menu. This belief can be based on previous experience on the water we are fishing, research, direct observation on the day (say, observing a few of those particular insects here and there), or trusted advice. For want of a better term, we could call this approach, ‘discretionary imitation’. More so than during a big hatch or fall, trout might be persuaded to eat a completely different fly, but we bet on the right imitation being taken.

Both of these imitative subcategories can lead to a deep analysis of entomology, stream sampling with seine nets, nymph-collecting (to hatch out in an aquarium at home) and other seemingly eccentric activities! Anyone who has read noted flyfishing authors like Vincent Marinaro, Swisher and Richards, Rene Harrop or Norman Marsh, will recognise the immense investment in trying to truly understand trout food and trout feeding behaviour.

Ideally, an imitative fly would try to do everything to replicate the natural. This would include features such as colour, texture, patterning, shape, size; and possibly even down to other distinctive elements like eyes, legs, shucks and gills. Subtle but often important elements, such as the imprint on the water (for example, the changing surface crease formed by a struggling tiny willow grub, or half-submerged mayfly or midge emerger) may require a certain gauge or style of hook to create the desired effect.

This imitative approach could also extend beyond the basics of fly design, and may take into account factors such as a good grasshopper imitation making an appropriate plop on landing.

Impressionistic flies

The next category of flies along the spectrum from imitation, are the ‘impressionistic’ flies. While these flies don’t try to exactly mimic a specific insect, they contain elements designed to trigger a feeding response from the trout. This might be something like a ‘generic’ mayfly pattern, in neutral colouring, such as an Adams. It might also have several ‘buggy’ features that don’t belong to a specific insect type. Something that looks a ‘bit like’ a mayfly, or a caddis, or small terrestrial. Some features might also be exaggerated (overall larger size, larger wing, or longer legs) to hopefully stand out as triggers to the fish.

While some enhancements might be admissible in impressionistic flies, if they go too far, we might end up in the next realm…

Attractor flies

At the far end of the fly spectrum are the attractors. These are the patterns which must have some passing resemblance to food in the eyes of a trout, but in artistic terms, could fall into the surrealist realm. Gaudy colours, funky foam, ludicrously long rubber legs.

Older flies like the Royal Wulff could squeeze into this category, while the Chernobyl Ant and similar creations unashamedly celebrate their ‘anti-establishment’ persona and look.

Sometimes, attractors (and to an extent, exaggerated impressionistic flies) are used specifically because they are different to the observed available food. This ‘anti hatch’ principle reflects the idea that the fly will stand out from the crowd of other food on the water, so the fish may (ironically) select it among the numerous identical real insects.

Attractor flies are also sometimes promoted as stimulating an aggressive or attacking response from the trout, in contrast to normal feeding behaviour. For example, this might be through vivid colours drawing out some sort of competitive/ spawning impulse, which maybe even the fish doesn’t understand!

Analysing anglers

Like any spectrum, there are overlaps and grey areas in how flies, and fishing approaches, fit into these three categories. To an imitation fundamentalist, an Adams might be seen as an impressionistic fly. But another angler might view the same as a good imitation of a particular mayfly. Similarly, patterns such as the Stimulator, tied originally as an imitative pattern for large American stoneflies, might be used impressionistically in places like Australia, where few if any stoneflies like that are a regular food source. Do the fish take it as a stonefly, a hopper, a large caddis or do they just see it as something ‘foody’?

So, the three categories have to be viewed somewhat subjectively, including in the context of the intent or philosophy of the angler.

If we wanted to stereotype anglers into these categories, we could make some of the following observations.

Imitative anglers:

On the plus side – highly analytical, trying to fully understand trout food and the trout’s environment right down to a scientific level.

On the minus side – place too much weight on the ‘intelligence’ of trout, and can be judgmental towards anglers who can’t recite the scientific names of insects!

Impressionistic anglers:

On the plus side – take a practical approach, and can simplify fly selection to a small box of patterns.

On the minus side – might be criticised for sitting on the fence, and being lazy by playing safe.

Attractor anglers:

On the plus side – willing to think outside the box, and challenge conventional wisdom, pushing the boundaries of orthodoxy.

On the minus side – oppositional for the sake of it. Possibly catch their share of dumb fish, and use that success to try to discredit hundreds of years of legitimate angling knowledge.

There are anglers who fit solely within one of these classes – I know quite a few of them personally! There is no law, however, against moving between any of the approaches, depending on the fishery, time of year, or just personal choice.

Ultimately, the trout are the judge, and the proof of the pudding is when the fish eats the fly. What we can’t answer, from the fish’s perspective, is WHY it ate the fly in regard to imitation, impression or attraction.

There’s also this question: if you do get a noticeable rejection from a fish, was it the wrong fly, or a bad presentation – say from drag? Either way, it’s risky to show the fish the same fly again. Sometimes a second cast will bring success, but in general, your chances seem to halve with each subsequent presentation. If you do change flies and the fish eats, you can stick with the new fly on the next fish, or go back to the original one. If enough trout are feeding, the pattern of success versus refusals, can help you to decide the suitability of your fly regardless of whether you are fishing imitatively, impressionistically or with an attractor.

With this in mind, let’s look at aspects of different trout fisheries and how they might help us decide which approach to take…

Fishery factors

Perhaps most relevant to an imitative approach is the physical nature of a fishery, and the food that supports it.

Starting with some general principles before moving onto specific types of fisheries, we have the following factors that come into play.

Fertility, food density and diversity

The more fertile the water, the more food it is likely to produce. This can be a combination of water-based fertility (which will grow aquatic insects, crustations, baitfish, etc.); and terrestrial fertility – growing food outside the water, which may end up in it (grasshoppers, beetles, ants, willow grubs… mice)! This fertility might come naturally from geology (e.g. limestone or basalt geology), or external influences such as fertiliser from farming. Typically, spring creeks and some tailwaters can fit this category.

In trout land, fertility generally produces more food, but it can do so in two ways. It can produce, at any one time, a single, dominant type of food; or, it can present a large smorgasbord of food for the fish to choose or ‘select’ from. I’ll expand more on this later, when I discuss specific fisheries and their challenges. In general terms however, trout in these waters have more than enough food to eat, and don’t need to desperately grab every available opportunity in front of them. This tends to encourage selective feeding over opportunistic feeding, and tips the scales well and truly towards an imitative approach.

At the other extreme are fisheries which don’t produce huge volumes of food, yet with quite a lot of trout competing for what’s available. These are waters where trout are more likely to be endlessly hungry and opportunistic: for example, your typical cold, tannin-stained rainforest stream.

Some other steep freestone creeks and rivers – and even certain high-altitude lakes – are in this category. Miss a meal, and a trout might be waiting a while for the next one to come along. Not to anthropomorphise too much, but we all know the feeling of hunger when food seems quite a way off. Do fish get ‘hangry’? I know I do!

Water speed and surface condition

The slower the water, the more time a trout has to inspect what it plans to eat. Still waters with cruising fish, or slow water where fish on station can inspect any potential fly carefully, give the trout time to accept (or reject) flies on both imitative criteria, and presentation (leader crinkle, micro-drag, etc.). A smooth surface only adds to the trout’s ability to find fault. Calm lakes, and low gradient spring creeks and tailwaters, with stable or managed flows, often present these demanding properties.

On the other hand, faster water limits the time a fish has to assess a fly critically, and a broken surface further conceals shortcomings with both the imitation and presentation. High gradient mountain freestone streams often have fast flows and broken surfaces, which both reduce the need for accurate imitation. On lakes or lagoons, a wind-ruffled surface tips the balance back in favour of the angler.

A mixed environment

The same as when we attempt to classify anglers, some streams may contain several or all of these characteristics. Headwaters of many streams tend to be faster and less fertile than downstream sections, and time of season can change flows and temperatures, but it’s worth recognising these features and how that might play into the need for an imitative approach.

Even time of day or a short-term weather event can ‘bring on’ a hatch… and selective fish. An example of this in Australia is where an impending thunderstorm can result in a large fall of winged termites. A seemingly dead river can come alive with rising fish, but good luck if you don’t have a suitable fly!

Hatch scenarios and trout behaviour

Whatever brings the food, and feeding fish, there are several basic situations which can occur. I’m generalising (again!) and there are the inevitable exceptions just to keep things interesting and to frustrate fishing writers. But regardless, observation of both food, and the fish’s feeding behaviour is a prerequisite for trying to imitate what they’re eating.

Overlapping hatches and truly selective trout: ‘technical’ fishing

The combination of a fertile, food-rich environment, with overlapping simultaneous hatches – on still or slow water – can make an imitative approach essential. Hatch charts for some iconic American fisheries can look like EOFY spreadsheets, with multiple mayflies and other insects all being on the menu at the same time. Times in central Pennsylvania, Montana, and on iconic waters like Henry’s Fork, Letort Spring Run, Oshino Stream in Japan, have been some of the most demanding and rewarding angling experiences of my life. Maybe it’s a relief that it isn’t always that tricky, but for me, if I didn’t know that things could get that tough, I would probably give up flyfishing altogether.

A curious phenomenon, alluded to earlier, is where the surface is blanketed in large numbers of several different insects at the same time. Many fish will focus on a specific food item, often the smallest one, and reject or ignore larger naturals. For example, on Penns Creek in Pennsylvania, I found trout ignoring plentiful large size 8 Green Drake duns, in favour of size 18 Sulphur duns. Or even ignoring both of these for size 24 Blue-Winged Olives. This is known as a ‘masking hatch’, as the larger and most noticeable food sources are masking what the fish are really eating. Additionally, when there are several trout rising, each of them might be doing something completely different. The only answer is to carefully watch one fish and make a choice based on what you observe it doing, before moving on to the next.

Single dominant hatches

More common (including in Australia) is when only one hatch is happening at a given time, or at least is prolific enough to make it the dominant food source available. These events can be just a ‘trickle’ of insects, but enough to get fish interested, or build into a steady hatch.

When the density is low, the trout will often show interest in any potential food coming into their window. They may even have an expanded feeding zone and be willing to move somewhat to inspect the fly. (Whether they eat it or not is another matter!)

If the hatch builds up enough, fish will tend to stick to a narrower feeding lane, as the food is presented to them often enough to have a steady rising ‘rhythm’ without expending much effort. As well as the fly pattern being right, it’s important to try and present your fly to the fish to match its rhythm.

Sparse hatches and ‘nothing to see here’

There are days (and fisheries) where specific insects might not be observable in sufficient numbers to be considered a true feeding event. There may even be no food at all seen on the water. In this case, you can still use the ‘discretionary imitative’ approach I described earlier. You can use an imitation of a known food source, rather than use an impressionistic or attractor pattern. I try to use this approach as much as possible, as I feel it keeps me connected (and attentive) to the environment I’m fishing in. I do have some fly patterns that are good imitations of common and widespread mayflies and other insects, but I no longer carry any attractor or generic patterns like Royal Wulffs, Stimulators or even my previously beloved Red Tags.

I don’t claim this is necessarily always more successful than taking another approach. And for the occasional or travelling angler, it’s a tough ask to expect them to research everywhere that they might end up fishing, and to understand all the bugs they might come across!

Knots and Magnifiers

Fly changes are often important for fooling selective fish. Unlike me, I hope you have no need for glasses to get the tippet through the eye of a hook. My eyes are okay, but without magnifiers, threading tippet through small flies especially, is not a trivial process. Repeated fly changes can go hand in hand with selectivity, so easy to access glasses can be a gamechanger. (I learnt this the hard way on Penns Creek, in evening light, without glasses!)

Similarly, the Penny Knot, shown to be by Peter Hayes, has made tying a knot simple and quick. You can tie it behind your back with a little practice!

Summing Up

An imitative approach is a combination of the fly used, and the way it is fished. Ultimately, it can be considered a philosophy as much as anything: if the angler enjoys it, that’s often reward enough. As to how it compares to other approaches catch-wise, the trout will be the judge…