FLYMPH FORUM

[quote="Mike Connor

Without knowing these relationships there is no sensible way to use any materials.

TL
MC[/quote]

Just a thought.

If jims assertion that his flies have benifted from the UV materials be considered as true there is of course another POSSIBIITY at work here, outside of, the trout seeing UV question . That being the POSSIBLE side effect of the additional UV reflection on other materials in the fly by causing other fluorescent materials to glow with visible light in a manner that somehow works. Pure conjecture and maybe not sensible at all considering, but at least fits in within the parameters of that we are certain that a trout can see.

In some ways, I wonder if this was ever truly understood, would it simply explain why tried and tested stuff works in particular and not really be the perfomance enhancing info that we may desire.

Indeed, that's the problem. I know that some stuff works better than other stuff on some flies and catches more fish under a VARIETY of conditions. Waterhen is one such material and starling is another. Starling feathers with some iridescence work best on some flies. Waterhen works very well indeed on some flies and has the rather odd "brown tone" and looks brownish in some light. I have been trying all sorts of things on both these feathers for quite a while but I have still not pinned down why they work so much better than other stuff which looks similar but only works under some or very specific conditions. My current surmise is that they appear more "real" to the fish in various light conditions. ( Once again translucence being a major factor).

Whether there is any UV related effect or not I can not tell you at this time and I may never be able to do so. Bird plumage does show patterns in UV light, but how or even if this relates to trout I have no idea. I need a lot more specialised pictures of actual insects and it will take me a long time to get them. If I then find similar patterns in the plumage , AND the insects, of flies that are known to work well, there MAY be a correlation.

I am still messing with a couple of special cameras and trying to set up lighting arrangements. To get correct results I need the same conditions for all subjects. Just using artificial light sources is not conclusive and using the only viable natural source ( The Sun) http://en.wikipedia.org/wiki/Ultraviole ... rces_of_UV is very difficult indeed for obvious reasons. It is even more difficult to get the insects at the right times and put all this together. There is not much point in trying to correlate insects that only hatch in dull conditions to conditions of maximum UV either. This is even less likely to be useful as trout actively avoid exposing themselves in such conditions.

Also, the amount of UV light varies a great deal at any given time due to various factors. Even if there is a UV related factor it will only work at those times when UV is actually present. The amount of UV light may also have an effect.

At present, my tentative conclusion is that IF there is a UV correlation it is is in any case very limited, and even if known would not make a lot of difference to the choice of fly-dressing materials. Choices made based on appearance in the visible spectrum would still be paramount.

TL
MC

There is some information available on starlings;:

http://jeb.biologists.org/content/205/21/3299.full

http://www.pnas.org/content/94/16/8618.long

http://www.sciencedirect.com/science/ar ... 7202919779

http://beheco.oxfordjournals.org/content/16/4/805.full

You have to read a lot!

Whether any of this is actually or potentially useful to you in dressing flies is a moot point. How it might relate to possible UV correlations in artificial flies and fish senses is also difficult to determine, but you have to start somewhere! There are very many unknown factors and variables.

I do this because I would like to know why some things are as they are, and how one might make them work better. I do not expect other people to agree with anything I say or do, and I don't mind at all if they disagree, even vehemently, as long as they stay civilised.

I catch plenty of fish with the flies I use, and I am not looking for a "magic bullet" or an "infallible fly", just attempting to learn as much as I can.

TL
MC

Hi Mike,
The term tropism was used to explain inborn responses of very basic animals, plants, etc.. We used it in Biology, Zoology and Botany classes. There are positive and negative tropisms. Trout are negatively phototropic, as Mr. Heacox explains. They have other negative tropisms as well.

Mark

Soft-hackle wrote:Hi Mike,
The term tropism was used to explain inborn responses of very basic animals, plants, etc.. We used it in Biology, Zoology and Botany classes. There are positive and negative tropisms. Trout are negatively phototropic, as Mr. Heacox explains. They have other negative tropisms as well.

Mark

No problem. There are various usages and interpretations of lots of things, all valid in their own context. Problems arise when these usages are not common to the participants in any particular discussion.

I am not disagreeing with you, I am merely pointing out that I understand something else as "tropism", basically this;

http://en.wikipedia.org/wiki/Tropism

Obviously this is somewhat different to your understanding of it, and that of Mr. Heacox. That does not invalidate those interpretations, it merely demonstrates that they are different.

TL
MC

Understand Mike,

Looking at the definition:A tropism (from Greek τροπή, trope, "a turning") is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus. In tropisms, this response is dependent on the direction of the stimulus (as opposed to nastic movements which are non-directional responses). Viruses and other pathogens also affect what is called "host tropism" or "cell tropism" in which case tropism refers to the way in which different viruses/pathogens have evolved to preferentially target specific host species, or specific cell types within those species. Tropisms are usually named for the stimulus involved (for example, a phototropism is a reaction to light) and may be either positive (towards the stimulus) or negative (away from the stimulus).

Tropisms are typically associated with plants (although not necessarily restricted to them).[1] Where an organism is capable of directed physical movement (motility), movement or activity in response to a specific stimulus is more likely to be regarded by behaviorists as a taxis (directional response) or a kinesis (non-directional response).

This definition fits fine. You will notice it says tropisms are typically associated with plants but are not restricted to them. It is generally associated with movement either towards the stimuli or away from it (taxis) or just a non-directional response (kinesis).

Mark

Part of the problem I see is the understanding and implied expectations of UVa reflective material.
First it really doen't matter what color or how UVa light is percieved by a trout. If the insect is reflecting Uva light and a material used in a fly is reflecting UVa light. It is a reflection of the light source.

I would think another misunderstanding is "glowing fluorescence", this is not what is trying to be achieved at least in this application.Mayflies for instance do not reflect UVa light through out the entire insect but in only specific parts of the body. I would think this is what is trying to be replicated using UVa material. If a fly is loaded with UVa material it will look unnatual and just may well be repulsed.

Trout do not lose their UVa vision as they get older but there is a reduction of this vision. As they spawn the UVa vision is at it's strongest. This is clearly stated in the 2002 study.

There is a book written on this subject by Reed Curry.
Jim

Jim Slattery wrote:Part of the problem I see is the understanding and implied expectations of UVa reflective material.
First it really doen't matter what color or how UVa light is percieved by a trout. If the insect is reflecting Uva light and a material used in a fly is reflecting UVa light. It is a reflection of the light source.
Jim

Surely Jim it does matter "what color or how UVa light is percieved by a trout" - that is the crux of the matter. If as you say and it would be useful if you could point us to some data on this, that mayflies have portions of their bodies which are UV reflective the incorporation of UV reflective materials in our patterns only makes sense if the trout can detect the presence in both the natural and our mimic. For all I know, a mayfly may be firing photons out its ass, unless a trout can detect them and uses that as a recognition factor, there is little use in me incorporating a photon generator into my patterns - now that would test a few tiers

In the case of Brown Trout the scientfic evidence is that except at spawning their ability to detect UV has diminished considerably if not completely disappeared. Is it at all probable that a species such as brown trout would show a major if not almost total loss of a sensory function at maturity if that sensory function was to play an important role in prey detection. Generally in nature the opposite would be the case, the sensory function would be expected to honed if it were to play a part in that vital aspect of the trouts ability to survive.

That Jim, aside from my own use of such materials which proves nothing, is why I am extremely skeptical of accepting the inference that the UV element of the materials you have used in your sucessful patterns is the key to their success. I do not take a Halfordian approach to such things and will embrace any advance in our knowledge where in my view such an approach makes sense and is likely to give advantage.

That flies incorporating UV reflective materials catch trout is not sufficent proof for me that these materials offer any advantage over other materials and so I make my choice not to use them at this moment in time. No big deal really.



This is from MARK E. DEUTSCHLANDER*, DANIELLE K. GREAVES, THEODORE J. HAIMBERGER AND
CRAIG W. HAWRYSHYN 2001
"
Juvenile brown trout possess
accessory corner cones over the entire retina. 1-year-old brown
trout possess accessory corner cones only in the dorsal portion
of the retina. However, 2-year-old brown trout show an almost
complete loss of accessory corner cones over the entire retina,
with the exception of a small number remaining along the
embryonic fissure of the retina (Kunz, 1987). In our study, it
is entirely conceivable that we have only caught the first phase
of reduction in ultraviolet sensitivity, and further examination
of older fish may reveal a complete loss of ultraviolet
sensitivity in O. mykiss. If this were the case, then regeneration
of ultraviolet-sensitive cones into the dorsal retina at sexual
maturity would have to occur to produce the adult pattern in
the retinal mosaic (Beaudet et al., 1997).

"

My primary purpose in studying this is to make better flies for myself, and to eliminate things which are of no use to me. As I already wrote, I am not looking for a "magic bullet" or an "infallible fly". I am just trying to make my imitations as accurate as possible so that they work well for me.

With regard to these two things: UV related phenomena, and "positive triggers" making artificial flies more attractive to trout, I have no data that supports either contention, with the exception of movement in some circumstances as a "positive" trigger. It can also be a negative trigger. There are some colour triggers which affect fish, the reactions of a male spawning stickleback to the colour red is a classic example and it may well be that other spawning fish react to certain colours. Bright red in a fly might make spawning steelhead attack that fly, for instance, but I don't know this for certain. In the case of the stickleback the red colour is a key stimulus which triggers an innate releasing mechanism and this results in a fixed action pattern. For more information on this, see;

http://www.sparknotes.com/biology/anima ... ion1.rhtml

http://en.wikipedia.org/wiki/Fixed_action_pattern

Just like everybody else I am obliged to dress my flies based on my own perceptions. Up to now I have found that most of my failures were due to my not having perceived something that that was there but perceptible if one looked properly, and all my successes are due to my having noticed something about a particular material or a particular prey behaviour. Direct observation of trout behaviour is also useful. Understanding the motives and perceptions of trout is not required, which is just as well as it is not possible! One merely needs to know how the fish reacts.

There are basically three main factors involved, appearance, colour, and movement. All these are variable and may differ under various circumstances.

I already know that these factors work on artificial flies, because there are many patterns based on these factors which work well, and I also have some of my own. These factors are directly observable as long as you look at them under the same conditions in which the fish see them.

Factors like UV light may or may not play a part in the appearance or colour of flies but there is no way to observe it. If you believe that adding materials affected by UV light to your flies makes them more effective, then you have made an assumption for which there is no known basis in fact and which you can not observe. Nor do you have any means of knowing which materials to use as you can not (normally) perceive their effects.

If you catch ten trout on one fly and none on another under the same circumtances, and you do this cosnistently, then you have some very basic data to work with. There must be a reason or reasons why the fish take one fly in preference to the other.

There is no data extant on UV-related materials on trout flies. Nobody can give you any. All those who are convinced say things like "But it works better", and stuff like that. That is not data it is merely unsupported belief.

The same applies to "positive triggers" on flies, nobody can give you any data. They all say similar things about the "positive triggers", but nobody can give you a single example that is known to work.

People believe lots of things, many of them quite abstruse, but that does not mean any of them are true. Conversely you don't have to believe in something to know and observe that it works.

There is no causality* evident in the cases of UV light effects, (including fluorescence), and so called positive triggers. These are things that people believe for no good reason. I do not believe anything at all without a reason, it is pointless and will merely confuse issues. I am well aware that a lot of people do take an enormous amount of stuff on faith. That is up to them, I prefer not to do so.

*http://en.wikipedia.org/wiki/Causality

TL
MC

Back to more simple issues on Colour.

I am sure that many of us have come accross the situation where specific flies that work for a specific hatch on occasion fail to deliver the results that we have come to expect from the fly. The challenge is too find out why, is it the fly, are the trout feeding differently, are they feeding on something else that we have not noticed, have the trout been caught too many times and thus a little more wary etc.... This can be particularily difficult at dusk, often you are relying on basic experience, knowing what should be on the menu and paying attention to rise forms to assist in your determinations.

One such experience I have had was with BWO hatches. A particular pattern that in the first season I used it worked extremely well, takes were confident, very few last second refusals and worked consistently well. The following season it also worked well, but one particular night whilst I caught many trout my fishing buddy caught very few on his tying of it. I gave him one of mine and soon he rod was bending regularily. Back at the car we compared patterns, mine was tied with red thread, his with olive green. Back home , I took out the original prototype that I had been given by another friend, it too was tied with Olive thread. So I had been using an incorrect pattern for a couple of seasons. This none the less was to prove fortuituous, the originator of the fly had stopped using it as he had found that it was not as consistent that he had first thought and basically said that this was not unusual, he had found this to be true with many patterns over the years.

I could not buy into this , there had to be a reason, the hatches were the same, the trout were doing the same thing and as I say, by chance the thread colour issue had arose. Last season I had not as many evenings on the bwo's as I would like, but I was however armed with both versions and verified ( not enough times to say beyond reasonable doubt ) that the thread colour on some evenings mattered, on other evenings there was no differential between the success of the patterns. I have not yet identified the reason for this, it was not a clear cut case of a glowing orange sunset versus a dark sky - more research is needed on the water. Incidentally , all three tiers worked off the same batch of mixed dubbing so there was no difference there.

Clearly this is on face value a simple example of same materials, different thread colour. Even such a simple obvious example may not be clear cut in the WHY one worked significantly better. e.g. Were there significant numbers of spent spinners on the water when one of particular thread colour worked better than the other and were some trout accepting it as a spinner ? This particular pattern is tied on a curved hook and fished semi submerged, was it been sometimes taken as an emerging caddis rather than its function as a BWO emerger. Was it the background lighting conditions. Was it something else.

One can only work within the boundarys of ones knowledge in reaching any tentative conclusion. I can only conclude that the colour mattered but I cannot say with any certainty that this was light conditions related or whether the pattern loosely fitted multiple items on the trouts menu.

Discussions such as these , whether on the specific nature of materials or on the more gerneral aspects of colour extends our knowledge and hopefully provokes us into being more aware of the multitude of variables that can affect our fishing and tying. I am gateful to all that have contributed to this discussion and eagely await any research that Mike is doing re the start of this thread.