FLYMPH FORUM

Mike

Do you have any studies on how fish may see or react to fluorescent colors as typified by UV absorbing materials? I test most of my "hot" or "fluorescent" color Steelhead tying materials in Fly Shops with UV light before I buy to see if they are in fact fluorescent (some are not as advertised). I base my tying on the visible spectrum and know I can't see UV but I can see reactive materials with a visible difference and I assume the fish can as well.

Roadkill wrote:Mike

Do you have any studies on how fish may see or react to fluorescent colors as typified by UV absorbing materials? I test most of my "hot" or "fluorescent" color Steelhead tying materials in Fly Shops with UV light before I buy to see if they are in fact fluorescent (some are not as advertised). I base my tying on the visible spectrum and know I can't see UV but I can see reactive materials with a visible difference and I assume the fish can as well.

Sorry, no I don't. All I basically have on that is my own experience, a fair number of experiments, and what other anglers have told me. No concrete evidence at all.

Indeed, when I tried a lot of fluorescent stuff I based my dressings on the same principles, the visible spectrum. I thought there might be an advantage in having a "brighter" fly. Brighter because the fluorescence actually increases the amount of light from the fly if enough UV light is present, the"normal" reflected light and the added emitted light. I found no difference at all in most use, although some flies did look brighter in good daylight, they didn't catch any more fish than flies without fluorescent materials, and occasionally a lot fewer, especially in green and blue shades of fluorescence.

Based on that theory such flies might be more effective in bright daylight ( or sunshine), ( that is the only time there is sufficient UV present to make the fluorescent material emit enough light to make the fly appreciably brighter). Unfortunately, that is also often the worst time for fishing as fish avoid bright sunlight and even bright daylight is often very bad, especially for surface feeding fish. Also, there is really no reason to assume that a fish will prefer a "bright" fly to a dull one. Real flies are as they are and making an artificial "stand out" by making it brighter is just as likely to cause a fish to refuse it. It was a series of experiments I did when this material first became popular. I don't use it any more.

You have to be careful with a lot of fluorescent stuff as it may well fluoresce in an entirely different colour to the one you want. Looks red in "normal" light and fluoresces blue for instance when in the presence of UV light.

You can see this effect here;

http://info.bluequillangler.com/blog/bi ... -Materials

Here are some effects of fluorescence, scroll down for the article on materials and comparisons in various lighting;

http://www.skiptonflytyers.co.uk/snippets.htm

All in all I have abandoned the use of fluorescent materials as I could find no advantage at all, and I think it may actually be detrimental in some cases. Especially if artificial flies glow blue or green etc. No real fly does that, so why should an artificial that does it be successful? The blue and green fluorescing flies I tried were definitely a lot less successful than "normal" flies. On yellow, and red, I could not be sure. But they definitely did not catch more.

That's about the extent of my thoughts on the matter.

TL
MC

Of course, if real flies had fluorescent "hot spots" you could see it yourself. I have not found any flies that have them. It would be completely unnatural in any case, no prey evolves to make itself more obvious and "attractive" to predators. Indeed, in cases where many insects are brightly coloured it is to warn off predators.
So my conclusions there are that most of the time it doesn't make much difference, ( not enough UV), and when it does the result is often negative.

TL
MC

A couple of people e-mailed me about this statement at the Blue Quill URL I posted;

QUOTE
Fluorescent types of material reflect light at a longer wavelength than it receives.
UNQUOTE

This statement is completely false. Fluorescent materials do not reflect light at longer wavelengths than they receive. They emit light in the visible spectrum, this is in addition to the normal reflected light.

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

Since this seems a reasonable point to sum up a bit:

I think that many people use flies of the wrong colour, because they do not look at them as the fish look at them. I think that fish see much the same as anglers and fly-dressers when they look at the flies in the same way. This is borne out by the consistent and very long standing success of many patterns.

The translucence colour of some flies is of major importance and largely ignored by anglers. Under certain conditions, if the translucence colour is not right you wont catch much, even though your artificial looks OK to you.

I don't think fluorescent materials are much use at all for artificial flies.

UV light is irrelevant, as if it had any effect on the visible colour of flies you would see that effect yourself, and in any case fish avoid UV light.

That's about it really.

TL
MC

May also be of interest in this regard;



TL
MC

Mike Connor, Howdy;



About time some jocularity was injected into this thread.

hank

I am not here to argue with one's experience or personal preferences, but I've got a few things to say that may figure into things here. My belief is that yes trout are probably affected by UV light. I Think we would agree that as the ozone layer thins, the intensity or increase in UV light is often detrimental, but I would say that it's not necessarily UV light they avoid. I believe that trout are negatively photo-tropic. Remember learning about tropisms in Biology class. Trout have an aversion to light-period. I would guess this is the case for a number of reasons.

I guess I'm in the middle concerning the usage of reflective materials for tying flies. I feel in some instances, reflective materials makes a fly appear more translucent if used in a specific way, and this can make it more effective. Regarding triggers--I believe it behooves us to build positive triggers into a fly we are tying to imitate a natural-taking our cues from the natural. Leaving out certain aspects might also help the imitation more like the natural. Certain reflective materials might imitate certain characteristics of natural insects. Translucence, reflective qualities, polarization of light could all be represented by reflective materials.

That said, I am of the strong opinion that fly behavior is much more important, and probably the first step in whether a trout will accept the fly as real. I feel it is important that we consider all aspects of the business at hand,and make our judgements based on our experience. You can not argue with success, but it may come differently to different people based upon a number of variables which we have no control over.

This brings to mind a story of a fisherman fishing to a particular trout spotted in the water. The fisherman made repeated seemingly flawless casts to the fish's near side so as not to show the leader to the trout, but the fly was not taken until the fly was presented further out past the trout's nose. After landing the fish, the fisherman realized the trout had been injured and was blind in the near eye. The fish could not possibly see the fly where it was first being cast by the skillful angler at first. Different situations and experiences yield different ideas on what is what. I'm sure if the fisherman had not increased the distance of his casts, he most likely would have surmised the fly was not right.

Mark

That reminded me of a large fish, ( for that river), I caught more or less by "fluke" on the Wharfe many years ago. It lived ( and fed) in a tangle of tree roots and lots of people had tried for it as it rose quite often. It ignored all the flies thrown at it. I decided to have a throw at it one day just for the hell of it although it was known to a few anglers as an "impossible" fish.

I flubbed the cast and hit the tree, the fly fell on the tree side of the fish only a few inches from the tree itself, the fish rose and took immediately. After a fairly prolonged and most peculiar tussle where it made a hell of a commotion apparently plunging in circles in the tangle of roots, I eventually managed to extricate it from the roots. It weighed two and half pounds, and seemed quite healthy, except that its left eye was missing and it was black on the left ( river) side. Apparently it could not take any flies which landed on the river side of its hole because it could not see them. My fly had dropped on its sighted side by pure luck.

Obviously all the anglers who had tried for it had cast to what they thought was the best position for the fly, as indeed had I on previous occasions, but the only position which could work was the few inches between the fish and the tree. I hit that very narrow lane by a fluke.

I have had a couple of blind and discoloured fish over the years, but that was the biggest.

TL
MC

Phototropism is something else again Mark.

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

Trout fry are uv-phobic. I have shone a uv light on to them in the breeding trays and they flee from it immediately. Brown trout fry will not flee from normal daylight but sea-trout fry will. Although they are genetically the same fish, or so it is widely accepted, they behave differently.

I think this is why they can detect uv-light with their eyes, They are cold blooded and can not detect it in any other way. They would otherwise get badly sunburned.

I use some reflective materials on my flies, most notably fine gold wire, but that also serves to make the flies more robust. At one time many anglers considered the use of any tinsel as detrimental.

TL
MC

According to the Scientific research, if I have read it correctly trout up to smolting stage have the necessary cone to detect UV light but that this ability has diminished in adult trout.

If this is fact then either

1. The UV reflective attribute of UV reflective materials cannot possibly have any impact whatsoever on a trouts determination on the taking of our flies.
2. There is something yet unknown occuring and it does have an impact.

No 2 is very appealing to our human instincts and desires, that "je ne sais quoi" - my fly has a hidden attribute and therefore when it is taken it cannot simply be the normal attributes of form, translucency etc.... it is the UV "je ne sais quoi" that worked in our favour. At this point any logical thought has flown straight out the window.

There is only one mind that can solve this problem and that is the ficticious but none the less infamous Sherlock Holmes - his saying going something like this
" “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.”

I would reverse this saying and apply it here " “Once you eliminate the probable, whatever remains, no matter how impossible, must be the truth.”

Those that are convinced of the benefit UV light being refelected by UV reflective materials in your fly designs have you eliminated the more probable answer that the non UV related properties of the materials in your fly was sufficent for the trout to accept your fly as food.

My problem with this UV stuff is that whilst the "je ne cest quoi" may be fun, a nice topic of conversation etc..., to believe that its the UV reflected light from our UV reflective materials that attracts the trout is as Spock would say " Captain, that is not logical - we cannot see UV light, adult trout cannot see UV light and who cares whether the Klingons can see it".

I think that looking at and understanding the impact of translucence colour, colour when backlit, colour from subsurface reflected light is more likely to yield benefits in our tying and understanding why certain flies work in particular conditions and thus enhancing our ability to catch and enjoy.