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Old 11-25-2012, 09:52 AM
silver creek silver creek is offline
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Default Re: Does blue excite the trout?

Hi Reed,

You said:

Quote:
Originally Posted by overmywaders View Post
silver creek,


No, your "direct UV vision" (what is "indirect vision") is a strawman. Photons in the range 340nm to 400nm striking any of the cones - red, green, blue, or UV - will be recorded. At dawn and dusk, most of the vision would be through UV photons; the same is true with the rods after dark. The higher energy of the UV photons vs. visible light, is also significant.

I am enjoying this discussion with you. I would like your take on the following which addresses the "strawman" allegation.

Let us exclude the UV cone for a moment since they perceive UV as UV. Let us consider the other cones (red, green, blue), which also respond to UV.

The brain interprets the signals from these cones as red, green, and blue respectively regardless of the presence of the UV cone. In other words, the presence or absence of a UV cone does not affect the intensity of the UV stimulus to these cones.

Therefore, the statement that the red, green and blue cones respond to UV should not be take to mean that they take the place of the UV cone or that as the UV cones regress, that the UV light stimulation of these cones increases to compensate. So the fish cannot separate what is UV and not UV light stimulating the red, green and blue cones.

The same is true of the rods at dusk. They perceive light intensity and not color so if shades of grey on a fly reproduce the light reflectivity of an insect, it would match the insect, regardless of the color.

If by strawman, you mean that my statement that the fish cannot separate UV from non UV stimulation of the red, green and blue cones is a strawman fallacy, I believe you are incorrect.

In my statement that trout see UV primarily as blue, you also said:

Quote:
Originally Posted by overmywaders View Post
silver creek,


Well, you think you know how trout perceive UV. That is interesting. However, as I stated in my last post, it doesn't matter how they perceive the UV, what is important is that they do perceive the UV; so it behooves us to dress our flies with the UV reflectances of the trout's prey.


I took the information that trout perceive UV as blue directly from your post. You wrote:

Quote:
Originally Posted by overmywaders View Post

Further, as Inigo Flamarique, who believes that trout lose all but a small percentage of their UV-specific cones at smoltification, wrote:

Quote:

MAIN SENSORS OF THE UV LIGHT WILL NOW BE THE BLUE CONES (WHICH HAVE THE PEAK ABSORBANCE-LAMBDA MAX- NEAR THE UV PART OF THE SPECTRUM).

Therefore, your allegation that I think I know how trout perceive blue should be directed at Inigo Flamarique, whom you quoted.

Regarding the dressing of flies with UV reflective materials, I agree that it would be useful if we knew what materials matched the UC spectrum of the natural we are imitating. That is the conundrum.

Since we do not see into the UV, we cannot tell if the natural has UV reflectivity, much less the intensity and shade of UV to use. I believe some insects such a beetles do reflect UV, but until there is some type of color system of UV material to match specific insects, I cannot see the benefit of using UV for UV sake except as an attractant strategy rather than a color matching strategy.
__________________
Regards,

Silver



"Discovery consists of seeing what everybody has seen and thinking what nobody has thought"..........Szent-Gyorgy

Last edited by silver creek; 11-25-2012 at 10:36 AM.
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