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Undercover Olives or The steak and nut theory

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Baëtis rhodani – Large Dark Olive Baëtis rhodani – Large Dark Olive

Even though more dramatic hatches may be happening, Andy Petherick is keen to urge you not to forget about the less obvious, that may prove more fruitful to the thinking fly angler.

It’s a funny old world. You wait all year for the mayfly hatch. Duffers fortnight, happy days. Big, fat trout, easy to see, and hopefully easy to catch. Don’t get me wrong, this is excellent sport, but there is another up winged hatch that due to its prolonged hatching season, and a few more attractive points (more on this later), the thinking angler should not ignore. Happily this phenomenon applies to both still, and moving water. I am of course, talking about, olives.

So how are the two linked? What on earth is he warbling on about? Let me explain. There are two separate elements here. The hatch timings, in that they cross over; and the more important topic of this feature, the olives them selves and their importance to fly anglers. There are a few species of olives that are of importance to the angler. I will look at Blue Winged Olives for my example; the other that is of importance is the Large Dark Olive.

Hatch timings – The steak and nut theory

ap1_649633485.jpgIn the past I have spent months preparing for this time of year. I have, as most anglers do, preoccupied, with the main hatch of May – the Mayfly. This, due to its hyped appearance, is an easy trap to fall into. I remember being stood on the banks of a well-noted southern chalk stream, watching rafts of mayfly struggling on the surface, trying to become airborne.

I saw fish rising freely, good fish, I could see them. Not recently stocked fish, but fin perfect, resident fish that every angler dreams of catching. Watching them I thought that they were feeding on mayfly, the obvious thing for them to be chowing down on at that time of year.

I tried everything to tempt them, every mayfly pattern, nymph, emerger and adult, I had to get that rise. I tried all sorts of tactics, long-range casting, Ultra long (16ft+) leaders, even, dare I say it, downstream dry fly! I don’t think that the owner of this site will allow me to type exactly the level of frustration that I was forming, at the lack of interest I was experiencing, less to say I was not a happy bunny, I just could not fathom it out. I left the bank that day, fishless.

At the time I worked as the fishing manager at Orvis in Stockbridge. It was rare that I caught nothing, and I was hugely frustrated. The following day I was in the shop serving the ‘Mayfly army’ that descended on that part of the world, at that time of year. I got talking to a gent, I wish I had asked his name, and told him of my frustrations the previous day, a smile broadened across his face.

A well-experienced angler, he told me of his experiences. He told me that he had been in a similar position a few years earlier. He also told me about the steak and nut theory. He was convinced that, more experienced fish (the ones we want to catch!) simply got fed up with mayflies after gorging on them for any length of time. He likened it to a human gorging on steaks for a week. Despite its initial appeal, it would soon wear off. After this level of feeding, any sane being would turn to a smaller food source, he used nuts for his example. Essentially Mayflies were the steaks, Olives were the nuts.

ap2_617179556.jpgEnlightened, I prepared for my next day, the following Saturday on the river. Armed to the teeth with olive imitations I hit the river. Sure enough the mayfly were out in force, and the same situation I had experienced the previous week, kicked into gear again. This time I was ready.

Initially, as before, I saw nothing, Mayflies are big flies, and the shucks litter the river making it hard to see anything else as obvious. The fish were rising freely, and with the aid of a small pair of binoculars I spotted some adult olives sat on the surface. Sure enough, I tracked a few down the river, and the were gobbled up in preference to the Mayflies.

Needless to say I tackled up with a dry Blue Winged Olive (BWO) imitation, and scored well that day, six fish to be exact all on CJ’s Ducks Dun, an excellent BWO imitation. All were better resident fish from the slack water at the tail of a large pool. I owe that gent a beer! I learnt three things that day.

1. You never know it all.
2. Be observant; look closely, even if the solution looks obvious.
3. If you are failing with the obvious solution (Mayfly) there is a reason!

Since experiencing this on a river, I have also seen it happen on a few still waters, Notably, Avon Springs in Wiltshire and Lechlade (also Bushy leaze) in Gloucestershire.

The Olive Family

‘Olives’ are part of 51 species of British Up-wing flies or Ephemeroptera. Up-wing flies are more commonly known as mayflies, although this common name is quite misleading because this group of flies can appear throughout the year. In fact, at one point they were called 'dayflies' due to some of the species having an adult life of a single day. The common name is derived from the habit of one species, Ephemera danica, or the more common Mayfly.
The up-wing flies are common within freshwater habitats, both river and still water. They are generally very sensitive to changes in water quality and water flow in the watercourses in which they live. As a result the larvae are good indicators of water quality.

Where do they live?

Olives are found as larvae in rivers and streams throughout the British Isles between April and September. They emerge as adult flies most commonly in July and August where they can be seen flying above rivers and streams and near bankside vegetation. Adult emergence timings are heavily dependant on temperature, weather, and locality.

Life Cycle

ap3_450323671.jpgThe general olive life cycle starts with the males forming a swarm above the water and the females flying into the swarm to mate. The male grasps a passing female with its elongated front legs and the pair mate in flight. After mating, the male releases the female, which then produces a ball of around 1200 eggs. This egg ball is held under the female's tails and dropped into the water as she flies over it. After releasing the eggs, the female usually falls, spent, on the water surface.

The eggs fall to the bottom of the water where they stick to plants and stones. The eggs develop quickly in the autumn until they are just about to hatch. They then stop growing and spend the winter at this stage. When the water warms in the spring the eggs hatch and the tiny larvae start feeding. They grow rapidly through a series of moults (or instars) and the first adults are usually seen in late June. The larvae usually swim in short bursts, interspersed with periods of clinging to submerged plants and stones. Known as a 'collector-gatherers' olive nymphs feed by gathering fine particulate organic detritus from the sediment.

Emergence of the adults takes place on the surface of the water during daylight and at dusk. Up-wing flies are unique as insects in that they have two winged adult forms. The larva or nymph emerges from the water as a dull-coloured dun (or sub-imago) that seeks shelter in bank side vegetation and trees. After a period of a couple of hours or more, the dun once again sheds its skin to transform into spinner (or imago).

Rise Forms

Since my experience on the river that time, I have been fortunate enough to fish, and work with some of the best names in the business. Notably Charles Jardine. Charles opened my eyes to studying the rise forms of fish, before tying a fly on.

Once you have identified the species they are feeding on, stop and watch for a few seconds. Fish bulging/boiling beneath the surface will be intercepting the nymphs. If they are high in the water, just breaking, or just below the surface, consider using unweighted nymphs, or having a CDC dry to hold the fly up in the upper part of the water column, in the feeding zone. The CDC will also act as a take indicator, unless it is the one taken!

If the fish are confidently rolling over the adults, then dry fly reigns supreme. Don’t get too caught up in this though, be aware that they will also take nymphs while feeding on the surface.

In my experience they are less likely to look at dries when on nymphs, but more than likely to look at nymphs when feeding on dries.

ap4_188144571.jpgFlies to use

Dry Flies – Olive CDC, ‘F’ fly, Ducks Dun, Spent Spinner, Elk hair emerger, Loop Wing Emerger, Parachute Adams, Any BWO imitation, and adult Baetis imitation.

Wet Flies – Shuttlecock Emerger, Waterhen Bloa, Greenwells Spider, BWO nymph, Baetis nymphs.

NOTE: Make sure that the size of your imitation matches the flies that are showing.

Be flexible

OK, so you have sussed out that the fish on the water you are fishing are feeding on olives. Don’t expect the hatch to start at the same time every day, it wont. Olives are very susceptible to climatic variation. Extremes in pressure and temperatures will mean that they will hatch very early in the morning, or late evening. Keep your eyes open, and be prepared to change as soon as you start to see obvious indications.

Fishing tactics

Whether on river, or Stillwater, whatever species of olive you are looking at, the tactics (happily) are the same. I would recommend nothing heavier than a 5-wt, and a leader tapering to a 3-4lb. These are small flies and need delicate presentation to convince the fish. Due to their ecology, there will be a lot of naturals around when a hatch starts, don’t make your fly stand out for the wrong reasons.
We have already looked at the nymph and adult stage, don’t forget the spinner. This is the only time I would jump up and down and say that it is pointless to fish anything else other than a single fly. Accurate casts are needed to feeding trout. Also, try and make the leader as long as you can handle, while maintaining turnover. Enjoy!


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