For about the past year, a few of us at the shop have been experimenting with UV fly tying materials. UV dubbing and UV Chewee skin have been a big hit for trout on the Mckenzie and Willamette Systems, and I’ve been working UV Krystal Flash and UV Polar Chenille into my salmon and steelhead flies, and it’s definitely given me more confidence in the patterns, especially in low-light conditions.
Recently, Marcos from Hareline Dubbin turned us onto a book by Reed Curry, The New Scientific Angling: Trout and Ultraviolet Vision that really will boggle your mind. We did a Q&A with Reed, posted below.
When incorporating UV fly tying materials, do you want to use ALL UV in a pattern? Just some? Is there a mix you like?
I suggest using an amount appropriate to the natural. For example, use no UV reflective materials on a beetle or cricket pattern, since the naturals absorb 90% of the UV light; on the other hand, most mayflies should have UV reflective materials for the wing and head. Caddis flies should only have UV reflective bodies, not wings.
How much does the visible light color matter with UV materials?
I would want as close a match as possible to the natural in both visible light and UV. This is less important at dawn and dusk, when the UV predominates.
The book mainly deals with trout patterns… Have you had much experience with UV materials beyond trout?
Nope, but any other fish species which has no UV filter on the lens of the eyes should, in my opinion, receive the same treatment. In deeper, clear water this would be true as well as the river conditions that I covered in the book. I believe out your way that fluorescent materials are popular for salmon and steelhead. You will note in the book that, coincidentally, fluorescent materials usually are also highly UV-reflective.
Why are trout especially sensitive to UV materials?
Mature trout retain or regrown some of their UV-specific cones – they begin life seeing only UV – however, even were this not the case, trout have no UV filter to block the UV rays from striking their retina. The other cones have a secondary peak in the UV, so trout have that as well. Yes, at certain times of day, dusk and dawn, the UV sensitivity may be greatest. Many other fish also have UV vision, however, I didn’t undertake to document that.
Do certain materials hold UV better than others? i.e Platics? Yarns? Latex?
“Hold” is a confusing term for me. The UV is reflected immediately; when no UV light strikes the object it ceases to reflect UV. If you mean do some materials reflect UV better than others, it is a matter of the pigments in the dyes. Theoretically, the same percentage of Titanium dioxide (rutile) will reflect the same percentage of UV no matter what medium it is in, plastic, yarn, etc. Natural materials such as white-tipped Turkey quills may be much brighter in the UV than, for example, some white-tipped duck quills. And the feathers of a turkey that is old or in poor health will reflect a lower percentage of UV. This is because the UV reflectivity of the feathers is the result of the actual construction of the feather and not pigmentation. Fortunately, the genetic hackles we use these days are always from healthy, relatively young birds; so dry fly hackles should be very consistent in UVR. The same goes for our domestic turkey and geese.