Trout Visual Acuity
A Digression on the Dry Fly Series - Part 5a of N
Not to put too fine a point on it, but a trout’s eyesight pretty much sucks. We’re out there fishing little size 24 thingamadoowops and think this critter’s got phenomenal eyesight. Actually it doesn’t.
To quote Jagger1 “The adult trout eye, with its large immobile pupil, is limited by chromatic aberration to resolution much lower than the diffraction limit, consistent with the low acuity reported for fish.”
Others have reported that a trout’s visual acuity if about 1/14 that of normal 20/20 human vision. For those of you who are shortsighted it’s akin to taking your glasses off and having vision like 20/280. Basically you see colors and forms and shades of light.
This is important as we get into discussing flies and patterns and such. It’s also a bit of a kick in the pants for those who think fish are tippet shy, and the alleged low visibility of fluorocarbons is worth a damn.
Just a short note here to set the stage. I was working on the next part and realized I may be saying things that won’t mean squat to folks who think trout have great eyesight. They don’t. It’s one of those myths. The lack of that eyesight also tells you why they eat some of the garbage we throw at them.
W.S Jagger, Chromatic and monochromatic optical resolution in the rainbow trout, Vision Research, Volume 37, Issue 10, 1997, Pages 1249-1254, ISSN 0042-6989 https://doi.org/10.1016/S0042-6989(96)00297-0 (https://www.sciencedirect.com/science/article/pii/S0042698996002970)
Wow. Good info. But I think I'll keep it to myself, knowing that all my buddies believe otherwise. In cases like this I ask myself "Would I rather be right, or happy?"