Tom (Afishinado),
I think during Trico time it's a bit difficult to actually pin down what may be "putting-off" your fish. The water level is usually at the seasons low mark and it's hard to say really if it's the leader shadow or something else...If we were in a good scientific mood we would somehow try to control extraneous variables and it may be impossible here to prove anything to a level of certainty. Until we can teach trout to speak to us.
1) The sun may just be illuminating in HD, from the fishes viewpoint, you... "Hey! What is that out there swinging that 8.5 foot stick around in the air?" Light maybe skipping off something on your rod, vest, sun-glasses etc. Spooking them a bit.
2) Once the little guy rises to your fly and the sun is shining on it he may say to himself, "Damn! Not Hi-Viz wings again...I'm so over those...That's so last year...If I had a pair of sunglasses I'd take a peek out there...I bet it's Gonzo...Hey guys! Try a little twinkle organza or something!...That Borger guy was on to something there..." That's the trout talking there not Spence, we all know he's still using wrapped hackle spent wings when he's not tossing his "secret" Datus Proper spinner...:)
3) "Bright lights, big city...Gone to my baby's head..." Any Jimmy Reed fans out there? Maybe the bright light is revealing your over-sized knot, the shine from your leader (not necessarily the shadow), or making it just a tad harder for the fish to see...Gray/dull background without glare may be better than a bright light in your face...Do you guys have "clay marl" patches in your rivers over there in PA? Rusty Gates use to tell me that his father would reach down and pinch a piece when he spotted one and rub it along the leader near the fly...Dull down its sheen.
I'm making jest here, but on the serious side I'm just saying it would be hard to say for certain that the shadow from the leader was the culprit and not something else...Maybe the bright light is just making them a bit more cautious.
I have heard anglers, as they were standing in the river trying to wish a hatch in to being, say, "When the clouds cover the sun the caddis will pick up"...I think what I'm saying or hinting at is we are observer's and our obsevations are limited by our sense's which are hopelessly flawed...When we are unable to put two & two together in to something that works in our heads...we just fill-in-the-blanks...If this delusion happens by accident to replicate itself we carve it in stone, very heavy stone and dangle it around our necks weighting ourselves down with what amounts to superstition and old-fart fishing lore.
Wow! What the hell was that?!
It's Spencer's "personal little box theory" creeping in to a fishing blog. The behavioral science boys call it "affirmation bias"...Image, for a brief moment, you are carrying a little box and in it are all your fantasies about how the world works...Everytime you bump in to something that sets well with your box of fantasies you cram it in to your box...If it doesn't you will probably ignore it...
The little fishy is doing something similar, in a very repetitious way, but if he screws up he will find himself in a lightly buttered pan with some seasonings...You and I, on the other hand, can walk around believing whatever wacky theory we can come up with and for the most part survive, and if we are lucky, not hurt anyone else with it...Bore them to tears with it, no doubt, but probably not hurt them...
Example: 1) Guy's bowling with some friends and he's had a few beers...
He tosses the ball down the ally and with a slight movement of the hip gets a strike...Next time up he's bound to move the hip...Harmless superstitious behavior...2) Guy wakes up one morning and thinks it's a good idea to torch a few Korans...Not so harmless and probably time to remove a few of those fantasies from your box!
Maybe we/Spence especially :) are over thinking this trout/angler equation and Spence is just reaching out just a little bit too far to make a point/joke!
Good luck out there!
Spence
"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively
"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood