WHAT BASS SEE
Boudreaux fishes the ugliest flies ever created. Cats throw up more appealing chunks than the glob of materials tied to Boudreaux’s hook, but Boudreaux fills his ice chest. Thibodeaux ties perfect replicas of insects, and minnows and crawfish and often gets skunked. This is largely due to the fact that Boudreaux will toss his flies into sure-to-get-hung-up places, like sunken timber and brush piles – where the fish are. If Boudreaux gets broken off he digs into his zip lock bag to pull out another three minute hairball pattern. Thibodeaux fishes open water because losing one of his three hour flies is painful.
Boudreaux puts his fly where the bass are and relies a lot on the fact that, comparatively speaking, bass can’t really see worth a damn. Boudreaux is wrong, of course, but not as wrong as you might think. It all started when Boudreaux was picking up some extra beer money helping old man Dujon clean out his garage. A July 1990 Fly Fisherman magazine was sitting on top of a stack. Boudreaux spent the next three nights reading “How Trout See” by an M.D. named Gordon Byrnes, some of which he understood and most of which made his brain hurt. But what he did understand led him to develop the highly successful Cat Puke special.
To think about fish vision requires that you go into their world or make certain assumptions. [Please note Felix Unger’s warning that you must always be careful because assumptions can make an ASS of U and ME.] Fortunately, Bob Underwood (author of Lunker) spent 1700 hours diving to study fish. From his experience we have actual observations to back up some of the assumptions we could make. Similarly, Dr. Loren Hill did an equal amount of research at Oklahoma State and created the Color-C-Lector (which helps fishermen determine which color of lure to use by dropping a light detector in the water to the depth to be fished and reading the color coded dial). I thank all of these experts for the background relied upon for this article.
Water is not ever perfectly clear. Even water that appears gin clear has particles that disperse or reflect the light. Water that is murky is filled with obstacles to vision. Water that is dark is dark. You get the idea. Which means that the first sight difficulty bass have to face is looking through a medium (the water) that is always trying to keep them from seeing clearly.
One advantage bass have over dogs is that bass can see in color. The retina of a bass’ eye contains two types of cells: rods which don’t see color but show light intensity, and cones which distinguish colors. Some of the fishing wise guys say it is best to mimic the color of the prey the fly represents (green frogs, blue dragonflies, brown crickets, etc.). Others say that cool colors (blue, green) retain their color better with depth of the water and should always be used when fishing deeper. Still others say that florescent colors are even better than regular cool colors at retaining the original color.
What science actually knows is that light is broken into its components (think of how you remembered the color spectrum as a kid using the pseudonym ROY G BIV – red, orange, yellow, green, blue, indigo, violet). When light hits the water, certain color wavelengths penetrate to different depths or distances (again depending on the clarity of the water). In clear water on sunny days, warm colors disappear in the order of the ROYGBIV spectrum, but unless you are trying to get a fly down to fifteen feet or more it doesn’t much matter. Of course, colors also disappear the farther away you get, which means that a red fly sitting fifteen feet away may be practically invisible to bass.
In cloudy water or on overcast days, colors fade much shallower or closer. But...because we sometimes live in bassackwards world, in off-colored water, where the most a fisherman can see down is about four to six feet, the colors which penetrate best are orange, green and red. Where you find muddy water, the only light to penetrate is the long wavelength (red color). “Why?”, because particles in the water eat up the shorter wave lengths. Confusing? Of course it is.
Does color matter? Yes and no. What bass notice more than color is contrast. A Chernobyl ant is often not made of colors usually seen in nature, but it stands out well to fish. Similarly, the popular red headed lure with a white body is a standard combination that nature ignores, and, although black and yellow is bee-ish, it probably works because the high contrast. Remember that a bass sees only the bottom and some of the side of your fly. Meticulously decorating the top of the fly is for your benefit, not the fish’s. Fortunately, adding a Chernobyl-style extra indicator layer of foam to help flotation won’t discourage bass from striking.
Like other predator fish species, bass have a fish’s version of good vision – 180 degrees for each eye. This allows them binocular vision in front and up, where the 180 degrees of the eyes overlap. There is a small blind spot directly between the eyes and a large one from the side fins backward and also under the belly. In the binocular areas bass have excellent distance vision, but outside of the binocular areas, a bass’s vision is roughly comparable to a human’s peripheral vision, with little depth perception and weak details. In these areas bass see movement, but not details of the object, and with none of the same precision as the focal point.
Why is this so? Humans have a relative weak lens behind the iris that adjusts to focus on objects. When you are resting, your lens focuses on infinity then changes shape if you want to examine something closer. As you age, your lens loses the ability to focus and that’s why you need glasses. Bass lenses are powerful and nearly spherical, and at rest a bass focuses slightly in front of and above its mouth. Because its lens bulges through the iris and pupil, a bass cannot dilate or contract its pupils. It focuses by moving the entire lens in and out. However, when a bass focuses, the structure of its eye allows it to focus simultaneously on everything in the direction it’s looking, from about six feet away to infinity. As a fly approaches a bass, or vice versa, the fly is inspected but the closer it gets, a strange thing happens. Outside of six feet the most noticeable detail is movement, with the fly still too far away to pick out precise features. Within the six foot range the bass’s vision is hampered by the lens’ focusing ability and the fly is first only a fuzzy silhouette then gradually shows sharper detail until it nears the blind spot. At this point, before it disappears, the bass must decide to eat it or not.
Babineaux is 90 years old. He's fished every day since his retirement. One day he arrived home looking downcast. “That's it,” he told his wife Jeanette. “I'm giving up fishing. My eyesight has become so bad that once I cast my fly I can’t see where it went.”
Jeanette sympathized and said, “Why don't you take my brother Alcese with you and give it one more try.”
“That's no good” sighed Babineaux, “Alcese is a hundred and three. He can't help.”
“He may be a hundred and three,” said Jeanette, “but his eyesight is perfect.”
So the next day Babineaux headed off in his pirogue with Alcese. He saw what appeared to be a log near the shore and made a cast.
He turned to Alcese and asked, “Did you see my fly land?”
“Of course I did!” replied Alcese. “I have perfect eyesight”.
“So, where did it go?”
“I don't remember.”
Bass possess relatively good vision because their eyes, and the water in which they live, have a higher refractive index. A refractive index is the measure for how much the speed of light is reduced going through an object. For example, typical glass has a refractive index of 1.5 but water has a refractive index of only about 1.3 and the fish is situated in water, so to achieve focusing the eye lens needs to be very powerful. Hence the lens is spherical with a high refractive index of 1.65. What does all that mean? Bass physiology is adapted to the light conditions in water. A bass’ lens bulges through the iris so their pupils do not dilate or contract but they have a special pigment that shields the eye from bright light and structures which amplify the incoming light allowing for good vision in low visibility conditions. To focus, the whole lens is moved, as in a camera (forward for near vision, backwards and downwards for distant vision). The eye is equivalent to a camera with an extremely wide angle of view and good depth of field.
Colorwise, bass see in black and white in low light conditions. The dimmer the light the more the vision is black and white. The brighter the light the more bass see color.
So what? Let’s put this into perspective of choosing a fly pattern. For prey to survive they must have cover and camouflage. Cover comes by way of structure or vegetation. Camouflage is a natural defense that allows prey to blend in with their environment. What bass must look for in that circumstance is the silhouette of the fly. An olive nymph in olive water may be invisible to a fisherman, but if it is correctly colored for the native nymph species, it can attract a bass because of shape and size. A sparkly gold nymph may have attributes to attract a bass’ attention, but if it doesn’t look food-ish, it won’t get eaten. Which logically leads to the combination of the best of both flies?
Consider for a moment that fluorescent materials are popular bass catchers. Fluorescence is caused when a tying material absorbs light on one wavelength and emits light on a different wavelength. Light that is invisible to humans (i.e. ultraviolet) is absorbed and emitted in a visible spectrum. Because ultraviolet light penetrates water deeper than other wavelengths, fluorescent colors are more consistent and brighter in all water. Basically, bass see fluorescent colors better. We would then expect that a fluorescent fly in a correct shape stands a better chance of getting eaten.
Geautreaux’s Aunt Jolie was a painter who, in the prime of her career, started losing her eyesight. Fearful that she might lose her life as a painter, she went to see the best eye surgeon in New Orleans. After several weeks of delicate surgery and therapy, her eyesight was restored. Jolie was so grateful that she decided to show her gratitude by painting fresco’s in the doctor's office. Part of her work included painting a gigantic eye on one wall. When she had finished her work, she held a press conference to unveil her work. During the press conference, one reporter noticed the eye on the wall, and asked the doctor, ''What was your first reaction upon seeing your newly painted office, especially that large eye on the wall?''
''Thank God I'm not a proctologist.''
In the next article we’ll look at the combination of visual clues and a bass’ lateral line system. Here’s a hint: a bass will initially know prey is around because it feels it before it sees it. A fly that is stationary in the water is only going to attract a bass if it is close enough to see.
Underwood, Bob, Lunker, Stroeger Publishing Company (Hackensack, NJ 1978).
Byrnes, Gordon, How Trout See, Fly Fisherman Magazine (July 1990).