Updated: Apr 27
The discussion of what a trout can perceive in terms of colors, tippet materials, fly lines etc. seems to always be different depending on who you're talking to. So many questions, so many answers. We tend to tie all kind of flies, explore different colors, sizes, silhouettes etc. but can we really know what the trout perceive? Or is this experimenting behind the vice more for the fisherman than the fish? Let us dive in to this interesting topic and see if we can get any wiser.
This is the first article in a miniseries where I'll dissect this matter. First of is colors.
"This means that as we see a dark reddish color the trout will perceive it in a more brighter red and is able to see red in a lower light situation."
Without going too deep into the mechanisms of the human eye to understand the trout eye we can conclude that a trout's eye is quite similar to the human eye. However there's a distinguished difference in terms of colors. The trout's retina have four receptors at the wavelengths of 600nm, 535nm, 440nm, 355nm. And for those who are not in to the functions of an eye, like me wonder of course; What does this mean? In simple words the second and third wavelength conforms to the humans perception green and blue. However, the first and last wavelength is different, the first one at 600nm conclude to the red spectrum of color but at a longer wavelength than what we humans can perceive, when the color red is disappearing from us the trout can still see the color because of its more sensitive range. This means that as we see a dark reddish color the trout will perceive it in a more brighter red and is able to see red in a lower light situation.
"However, the ability of the trout to recognize UV-colors seems to disappear around the age of 2."
On the other side of this spectrum is the ultraviolet (UV) color. This is not visible for humans but for trout it is. However, the ability of the trout to recognize UV-colors seems to disappear around the age of 2. But, some argue that the trout in time of their spawning gets the ability to see UV-colors during this period of time. So far, we've concluded that trout see colors, though different from humans.
What do trout actually see then?
As of this moment I have the 'Possum dubbing box beside me. The colors in the box contains of Black, Brown, Rusty Brown, Burnt Orange, Orange, Golden Stone, Dark Olive, Olive, Golden Olive, Gray, Natural Brown and Bleached Ginger. The color variation is extensively massive and go to your local fly shop and look inside their bins and you can see all kinds of combinations of colors. I do believe that color matters when it comes to fishing but to what extent I'm not sure. What I do know is that colors, more specific, the right colors catch more trout than other colors. Seriously, how many natural insects are pink? But despite that it seems it catches fish...Flash, and all kind of different synthetics seems to trigger some kind of response. They stand out.
Well, we know for sure thanks to science that the trout have a different spectra, we know what colors they can see but that doesn't mean we know how they will see it underwater. If we knew it would be vital for our fish catching rates, all we know is that color matters. But who said fly fishing should be easy? Think of it this way, when the human eye see the color orange which is composed of reflections of red and green the trout may register infrared that may come of that reflections. A trout's ability to detect differences in shades is according to researches highest in the blues, much lower in red and lowest in the green spectrum of colors.
One more thing to consider is how high or deep in the water column you fish. Infrared and UV penetrates the water differently. Whereas the infrared only is visible at the very top of the water column UV goes much more deeper. Another important factor that fly fisherman need to consider is the coloration of the water. Is the water crystal clear, brownish, dark etc. That will affect how different colors appear to the fish. Last but not least, the deeper we go or if the water is off colored the light will soon disappear and colors will only appear as shades of grey.
Last but not least, the best way to study this phenomena I've just discussed is to find yourself a clear lake where the trout have all the time in the world to study your offerings. Play around with different colors, shades of colors and do your own studies. I for sure does not have the answer. But maybe I inspired you to think a bit differently when it comes to this.