Friday, 8 August 2014

MCX Dark Shrimp - The Prototype

MCX Dark Shrimp Prototype 1 #9
(Tied by Darragh Digney)

It's arrived!  You will immediately spot its derivation from the starting point of the Cascade.  What are the differences and the reasons for them?

  • There is a greater proportion of black in the body, which also extends into the tail, in order to increase definition and detectability at lower light levels.  
  • The tail is made longer to allow shortening when water level and speed so dictate (see Hot & Cold Running Water posted in November 2012 for an explanation of the correlation between fly length and water speed).  You can cut dressing off, but as it doesn't stretch, scope for adjustment is handy.  I regularly reach for the scissors to tailor the overall dressed length of flies to the conditions.
  • The dressing is more sparse in order to gain slightly more depth without the need for a sink tip (of which more below).  
It's a nice neat, understated fly, with excellent detailing.  No doubt it will evolve during the development process, but I'm very happy with the starting point: thank you Darragh.

Photoshop Simulation

Here are a couple of photos with the normal water attenuation of the red element of the spectrum applied using Photoshop, at two different sample light intensities.  As usual the significance of the black for definition and detectability is evident.

Of course this sort of photo-simulation is no substitute for the real thing.  It's not intended to be indicative and relative, not precise.  But we do know what water and the stuff floating in it does to light, which we can simulate respectably.

To see what I mean, compare these two views of different rivers, one snow-melt fed, the other mountain spate fed, in almost identical conditions of light intensity, sun elevation and river height (+10").  From above the surface both samples appeared quite clear.


The green tinting of the Dee in early Spring is a product of the detachment and discharges of rapidly growing vegetable matter in the shallower stretches.  The background water tone is grey, which is what you would expect in the absence of rain run-off transporting peat fragments and soil particles into the river.

The dominant feature in the Findhorn 3 days after a 18"'/45cm lift is the effect of suspended peaty materials, which absorb a very high proportion of the red element of the spectrum (>35% per metre) and thus appear red to the human eye.  Indeed, the dominance of the red light effect diminishes the apparent visibility by over-saturating the image.  What the salmon makes of it is unknown, but the relative shift between the two tints is likely to remain broadly the same.

As I build an increasing library of underwater tones and analyze their spectral make-up, so I shall be able to calibrate the Photoshop simulations more precisely.  But they will only ever be approximations.  Nevertheless, uninformed observation can be far worse!  Not all water is the same.  Rivers differ by nature, tone and colouring tendencies as a result of their geography and geology.  And the angle of impact and intensity of the light is a major factor.  It helps to have an understanding of the medium in which you will present your fly.

The Trial Regime

The next step will be swimming trials and underwater photography at varying depths, distances, water states and light levels, which needless to say will be combined with plenty of random fishing experiments.  Salmon are a statistical and analytical nightmare, the very definition of random.  There's no consistency in behaviour; catching is a very rare event; each event is unique (in all its aspects); and the salmon refuses to undergo debriefing before release, so you haven't a clue why whatever you were doing at that instant worked (or not).  You catch a fish on an Ally Shrimp, but for all you know, it might have fallen for a Cascade or even a roast chicken in that moment of aberrant madness.  My first concern is with what the MCX Dark Shrimp looks like underwater, where it has to be mobile but stable; detectable at distance in a broad span of light and water conditions; and 'impressionist' rather than imitative.  Given some water in the Ure (and yes, it's raining today) the first stage trials should be the subject of my next post.  Even if the water isn't perfect the trials will give me a self-justifying excuse to get out for the first time since the end of May.

The Effect of Dressing Density

You might question the sparsity of the dressing, especially as full-bodied flies seem popular at the moment.  Recently I bought a small tube fly for research purposes that probably denuded a full coop of chickens in its construction.  I'm not convinced by ample dressing.  As a general rule in moving water and at common weight, more dressing generates more lift, which may not be what you want because presentation depth is important.  You might be surprised by the effect of small differences in dressing on the depth at which the the fly swims.

This is the Sparse Stoat's Tail, which I favour in clear, warm, lower water conditions for deeper lying fish, because, despite its diminutive size, it sinks like a small stone, especially in slower moving water.  This is very useful when your target zone is beyond the main flow and sinking time is at a premium. Two examples come to mind, one on the Carron the other on the Alness.  Both involved fish lying very deeply against the side of large rocks, which you could not get at from upstream.  It required a square cast and fast sink with minimum disturbance, which the SST duly delivered.

The small Blue Charm is my favourite for most summer low conditions, but even the small amount of extra dressing causes it to swim higher in the water.  An experiment on the Ure last year indicated that the differential between them could be as much as a foot (30cm) in some cases. As a result takes with the Blue Charm tend to be highly visible, whereas with the SST I have found that is rarely the case.  So please think about the depth at which the fish may be lying as an important factor in your choice of low water fly.

Given some more rain I'll be back to report on the first stage trials of the MCX Dark Shrimp in a couple of weeks.  In the interim, tight lines.

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