Sometimes we fail to hook a trout that 'rises' to our fly

Splashy unproductive rises are commom on fast flowing rivers in Devon (UK). I often fail to hook trout that show an interest in a dry fly.

There's a wealth of advice on coping with fruitless rises: sharpen the hook, use finer/softer/longer tippet, delay/alter the direction of the strike, use a softer/longer/shorter rod, change fly or hook size, reduce drag/micro-drag etc.

It may help to understand the problem by examining possible causes ...

It is worth considering whether lack of success is down to the trout 'rejecting' our offering, or an outright 'miss'.

I have stopped worrying about failing to hook fish that 'miss' my fly. This article ends by explaining why - in some circumstances -I welcome splashy unproductive rises ...

First it's important to distinguish between:
  1. A successful rise
  2. A 'rejection'
  3. A 'miss'

1. A successful rise

We all aspire to achieving a successful rise to our fly.

This clip from an Orvis video shows a large trout taking a fly drifing downstream.

Use the Full Screen icon on this clip's toolbar to get the best view of the successful rises.

2. A rejection

This clip from the same Orvis video shows a fish inspecting, and then rejecting an artificial fly.

There's a wealth of advice on coping with a rejection: reduce drag / micro-drag, use thinner tippet, change fly or hook size, etc.

Use the Full Screen icon on this clip's toolbar to get the best view of the rejection.

3. Trout can 'miss' natural flies

This clip from the same Orvis video shows a fish making three unsuccessful atempts to capture a natural fly.

I classify the rise in this clip as a pure 'miss' because it involves a natural fly. It is not 'rejection' because no angling error (e.g. drag) is involved here.

It's not unusual on local Devon rivers to see trout rise to a natural, miss and the natural continues its journey downstream.

Use the Full Screen icon on this clip's toolbar to get the best view of the missed rises.

I am interested in what causes a fish to 'miss' a natural fly. The next video introduces the difficult task faced by a trout attempting to intercept a natural fly.

An insight into the complexity of the task involved in capturing a natural fly

Ozzie Ozefovich's underwater shots show how a natural insect floating on the surface appears to a trout.

The video illustrates two important points:

  1. Trout see the world through a skylight - or circular 'window' - surrounded by mirrors.

  2. An insect's wings and feet are thought to 'trigger' the start of a trout's rise.

Use the Full Screen icons on this clip's toolbar to get the best view of the insect in the trout's window and mirror.

Marinaro's 'Edge of the Window Theory' explains how trout intercept natural and artificial flies

Marinaro (1995) summed up his extensive observational studies of trout feeding behavour as follows:

"It is an inescapable conclusion that the trout places the fly always at the edge of the window for all purposes: viewing, inspecting and taking"(Marinaro, 1995, p. 20)

At first only the legs are visible beneath the mirror then as the insect gets nearer, the trout can see more and more of the fly's wings in its window finally, when the insect reaches the edge of the trout's window, all of its body can be seen,

and the trout ingests the insect ...

Paul Schullery used the diagram below in his book 'The Rise' to explain how "The trout's suction feeding typically pulls a double-tapered column of water into its mouth along with the prey".

The prey is the black dot in the "... center of the column at its greatest diameter..."

We should be grateful that Paul Schullery has studied the original scientific papers and presented a very readable summary. He writes " The trout can exert an uncanny amount of control and precision in using suction.This is not just an indiscriminate vacuuming operation that sucks in what is nearby. As circumstances require, the trout can open or close its mouth at the right instant and to the right extent to tighten the focus of the suction, thus increasing the intensity and reach of the pull.

What can possibly go wrong?
A lot ...

We have seen that there is a sequence of events and behaviours involved in a trout consuming an insect that is resting on the water surface:
  1. detecting the insect's legs resting on - or puncturing - the 'mirror'.
  2. detecting the insect's wings in the 'window'
  3. detecting that the wings, body and legs are visibly joined together and maintaining this state. This only happens when the insect's body is in, or on the edge, of the 'window'.
  4. using the appropriate amount of suction to ingest the insect

Do young trout have to practice capturing surface food?

I wonder if some splashy 'misses' are made by young fish that are refining their abilility to wait until an insect is on the edge of the 'window' before sucking it in

Intercepting, capturing and consuming an insect may be an instinctive behavioural sequence that is only fully developed as the trout grows and practises this complex behaviour

Use the Sound icon on this clip's toolbar to hear the commentary

It's not unusual for complex behaviours to require practice.

The majority of brown trout in my local rivers in South Devon are small, reach sexual maturity when 6 to 8 inches long in their third year of life. We have sparse hatches of upwinged flies. Maybe these fish 'miss' dry flies because they have relatively little practice taking surface flies.

An example of the importance of practice

Newly hatched chicks have an inherited tendency to peck at objects which contrast with their background, at first their aim is poor but it does improve.

As the chicks mature (age) there is a steady improvement in accuracy even though they have not had any opportunity to practice pecking. At any age, 12 hours of practice greatly improves accuracy.

In young chicks pecking improves as a consequence of both maturation and practice.

Maybe missed rises are simply the first clumsy attempts by young trout to get a good meal

Always remember, practice, practice, practice doesn't always make perfect for any animal!

My conclusion is that true 'misses' as distinct from 'rejections' are just something we have to live with on local rivers. Reducing fly size and tying flies with softer materials may help.

But look on the bright side; your fly and your presentation was good enough to attract a response from a trout.

Tight lines! Paul Kenyon

The current article is a follow-up to an earlier piece on Vince Marinaro's ground-breaking book on trout behaviour

The importance of the trout's window and mirror

This video explains how trout see the world through a skylight - or circular 'window' - surrounded by mirrors. Marinaro's great insight was to recognise how trout use the position of the fly in this window to make an effective rise.

"Why does the trout keep the fly at the edge of the window?" Trout behave in this way in order to judge the exact position of the fly. By keeping the fly in a precise position relative to its body, the trout stands a very good chance of engulfing the insect.

References & resources

Link to the full Orvis video How to avoid micro drag with dry flies and nymphs

Link to the full Ozzie Ozefovich's video Trout Vision & Refraction

Link to To The Journey's End: The Lifecycle of the Atlantic Salmon

Paul Schullery "The Rise: Streamside Observations on Trout, Flies & Fly Fishing", Stackpole Books, 2006

Here is the link to my more detailed description of Marinaro's theory.

"How Does a Trout Catch a Fly?: Marinaro's "Edge of the Window Theory"

Bibliography for Marinaro's theory

  1. Clark, B. and J. Goddard (1980). The Trout and the Fly. London, Ernest Benn Ltd.
  2. Frost, W.E. and M.E. Brown (1967). The Trout.London, Collins
  3. Hewitt, E.R. (1948). A Trout and Salmon Fisherman for Seventy-Five Years. London, Scribner.
  4. Marinaro, V.C. (1995). In the Ring of the Rise. Shrewsbury, Swan Hill Press.
  5. Proper, D. (1993). What the Trout Said: About the Design of Trout Flies and Other Mysteries. Shrewsbury, Swan Hill Press.
  6. Right Triangle Angle And Side Calculator  http://www.csgnetwork.com/righttricalc.html
  7. Roberts, J. (1994). To Rise a Trout.Marlborough, The Crowood Press.
  8. Wells, M.J. (1958). Factors affecting reactions to Mysisby newly hatched Sepia. Behaviour. 13:96-111.
  9. Wilson, D. (1957). Fishing the Dry Fly. London, Adam and Charles Black.
  10. Wyatt, B. (2004). Trout Hunting: The Pursuit of Happiness. Stackpole Books
  11. Pennsylvania Fly Fishing Museum Association  Vincent Carmen Marinaro(1911-1986) Collection