After many hours reading, a column, and three blogs later on the subject of what fish see, I find that Iíve learned a lot on the subject. Yet, I recognize Iíve only touched the tip of the iceberg. The exercise was useful; in that, it has me thinking about a fish might be seeing when Iím tying flies, and even more so when I select a pattern to fish. Plus, it has whetted my appetite to learn more.
In summary, itís fairly obvious to me that many of our favorite sport fish use sight as their primary sense to feed, much the same as land based predators. One book I read talked of a study where bass upon hearing a sound immediately turned toward it in an attempt to visually locate the source. Further, top end predatory fishís brains, such as trout and bass, are heavily dedicated to vision. Examination of fishís eyes shows they have both rods and cones, thus they are able to see colors. Further, laboratory experiments have confirmed fish can distinguish colors. Yep, fish see just fine.
Yet, knowing fish have good eyesight, see color, and use sight heavily to feed still leaves a lot of unknowns as to what fish actually see. Why they strike lures that obviously donít resemble anything in nature still remains a bit of a mystery. Striking a chartreuse spinner bait for example. Given we canít read a fishís mind, knowing what a fish actually sees and understanding how they interpret that vision will likely always be beyond our comprehension. Iím OK with that as I believe there should always be a bit of mystery to fishing.
Itís very clear from my readings that for a lure to attract fish it must be seen. Rather a duh I know, but if your bait doesnít contrast with its surroundings, then fish may overlook it. Thatís where color, including fluorescence and phosphorescence, and waterís impact on color, comes into play. While I didnít come across anything definitive in my readings, Iím fairly sure that a bit of motion plays a big role in a fishís ability to pick your bait out from its surroundings. Moving my bait (salmon eggs, worm, etc.) now and then was a trick I used to get more strikes when those just sitting there with a brew in hand were fishless.
Understanding how colors appear at various depths and water clarities allows us to select lures that standout from the background. Essentially, the deeper you go, the less color is visible. In clear water, the reds, oranges are the first to get filtered out. Go deep enough and only blues and greens are left. Deeper still and all light is absorbed. Most ďcleanĒ fresh waters have a greenish tint, so the greens and yellows last longest, up to fifty feet or more. In dingy, stained waters (think runoff) light doesnít penetrate very far, a few feet at best, and itís the reds and oranges that remain. Thus, depending on the lure color and depth you fish it, that color may appear different to the fish.
Fluorescent colors absorb light of a higher frequency and emit light of a lower frequency. Thus, a fluorescent red lure may retain its color at depth red would appear black. But remember fluorescence only works in the presence of light. Phosphorescence (glow-in-the-dark) is what you need light to be seen in the dark.
Under low light conditions, including after dark, fish are looking into dimly lit backdrop. In those situations, dark lures contrast better. If you doubt it, try it after dark and youíll find it to be true. In well-lit situations, the objects that are bright and/or highly reflective are most likely to be seen.
So when selecting your fly/lure/bait under different light and water conditions, give some thought as to how your selection will contrast with the environment under those circumstances. In situations where the fish are feeding primarily by sight, they must be able to see your offering before they can try to eat it; make sure they can see it.