Trout eating a Royal Coachman just proves that trout are not very smart. They are just reacting to something that looks like an easy meal. When I am bobber fishing I will get quite a few rises to the indicator and the fish will ignore the midge or the nymph. The fish say wow look at that nice big juicy blob of power bait time to eat.

Lanny

Brent,

My wife Jayne and I spent time taking what I understand are the first ultraviolet reflectance photos of mayflies. But it took an entire book with about 150 photos to support the thesis regarding trout and their UV vision. So, I did my homework, else I would not have made that statement. Is it possible you haven't read the book?

There have been a number of studies of the vision of bluegills, green sunfish, and pumpkinseed. I haven't looked into it in depth. I can say that recently more species within certain families are being acknowledged with use of UV vision. Of one family of fishes, the Cyprinidae, (carp, roach, etc.) tetrachromacy (R, G, B, U) is becoming the default assumption. However, even if the species lacks UV-specific cones, unless the lens of the eye contains yellow pigments (as most humans) to block UV, the UV is going to be recorded on the existing cones or rods (in some species the rods are more sensitive to UV than to visible light).

IMO, a good test would be to take UV photos of male sunfish in different age classes and look for honesty markings. If they have markings only visible in the UV, it seems reasonable to conclude that those fish can see in the UV.

You could do the research into the sunfish and UV vision. It is fascinating work.


P.S. - Check out http://web2.uwindsor.ca/courses/biology/corkum/PDFs/Cogliati,Corkum%20-%202010.pdf

Possible? no, its an absolute certainty!
What is it called, and where can I find it? thanks. This is very interesting stuff!
Brent

Brent, follow the link in Reed's signature. The book is on the home page of his site.

The book is available on Amazon - https://www.amazon.com/New-Scientific-Angling-Ultraviolet-Vision/dp/0984086307/

What you can see under a blacklight is fluorescence, some UV photons being "shifted" to photons of visible light. You can't see ultraviolet wavelengths (exceptions: small children can, as can those who have the lens of their eyes removed in cataract surgery). All families of birds can see in the UV, some bats use UV, most insects, trout, some lizards, whitetail deer, etc.

Factoid: UV has been found to penetrate clear water to a depth of 600 meters. This why divers wear fluorescent patches on their wetsuits, after all color is gone, the UV will still cause the material to fluoresce brightly.

In the book I take the 24 most popular dry flies of 1980 and show them in visible and UV. If UV is valuable, those flies should have UV highlights where appropriate and none where not. I also show many fly tying materials in the UV.

Actually, most of my time is spent in looking at what I cannot see. For example - https://www.uvrdefensetech.com

I think we may be onto something with this UV stuff and science to fishing thing. I just hit my most productive flies with UV - Elk Hair Caddis in olive and light wing, Bead Head Pheasant Tail Nymph, Olive and / or black bugger, and sulfur dunn. Not a single one of them glow under UV. Maybe the fish can see in UV, but I wouldn't give up my traditional producing flies and start tying in 1980's fluorescent colors. Thought provoking as it is, I'm sure it will sell some books.

I will hold with Gila on this one - that trout (and other fish) are not incredibly smart, and will react on impulse to environmental and physiological conditions to presentations of food - that which looks or moves similar to food will get eaten, when hungry, and if it isn't food, they will spit it out (when they realize that hey, this fly doesn't taste like a stonefly - it's metallic! SPIT! - hookset - miss! DANG! - all in about 1/5 of a second).

You've obviously misinterpreted my attempt at humor about the 80's fluoro colors. Those 80's were a bad time for clothes and colors on us humans. I wouldn't discount your ability to research a fish's ability to see different than humans - most people have known that for years, just like deer and other non-homo-sapiens. That's why so many hunters spend big bucks to mask their clothing of UV light absorbtion. That doesn't mean that guys can't - and don't - bag a buck or two ever year wearing everyday plaid shirts with a big goofy safety orange hat. Trust me on that one, too - my whole family loves venison. Just like the slippery slope analogy of saying if you dispense with acknowledging that observing UV markings on insects will diminish a fisherman's ability to catch fish is simply assuming that the UV signature is the absolute key indicator for a trout eating. It may be one, and it may be important in some situations, but from my experience fishing, I haven't found that to be so true. Size, vibration (though not as important as with, say, fishing LM bass), color, movement (action), placement, depth, water conditions, etc etc... all play a part in what attracts fish, so different presentations are necessary, as I'm sure you already know. As far as the Royal Coachman catching fish, from a view under water, it appears to have a head, abdomen, and thorax, is drifting down the stream at the right speed, right depth (topwater/film), with the correct profile (buggy) and the desirable size above a feeding fish, it is going to be snatched upon. UV being a possible trigger for the fish? Very possible, one of them. Key, not likely. Otherwise, the white bugger (which fluoresces brightly) would outproduce the olive in almost every water condition.

I think that, with almost any endeavor of man, we all have our individual levels of interest. Plenty of us just tie up flies that we enjoy tying, or ones that have worked for us in the past, or just appeal visually to OUR eye.
Very few of us are interested in the esoteric aspects of rod taper, or leader design, or exact line weight ratings, or UV profiles of insects and various flies. But thank goodness there are folks who DO find these things interesting and more importantly, have the patience and aptitude to study and understand them. These sorts of intellectual endeavors further the sport/pastime and increase our understanding of what works and why.
I'm not sure we can ever fully understand why a fish takes a certain fly at a certain time and not another. But if the goal of fly tying is to create a fly that, to a fish (rather than to the tier), resembles its prey species, then understanding how a fish sees a fly is a darn good start.
Brent

IMHO those flies work because of their size and profile.